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l2tpns.c

// L2TP Network Server
// Adrian Kennard 2002
// Copyright (c) 2003, 2004, 2005 Optus Internet Engineering
// Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced
// vim: sw=8 ts=8

char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.161.2.1 2006/06/22 15:30:50 bodea Exp $";

#include <arpa/inet.h>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/if_tun.h>
#define SYSLOG_NAMES
#include <syslog.h>
#include <malloc.h>
#include <math.h>
#include <net/route.h>
#include <sys/mman.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <linux/if.h>
#include <stddef.h>
#include <time.h>
#include <dlfcn.h>
#include <unistd.h>
#include <sched.h>
#include <sys/sysinfo.h>
#include <libcli.h>

#include "md5.h"
#include "l2tpns.h"
#include "cluster.h"
#include "plugin.h"
#include "ll.h"
#include "constants.h"
#include "control.h"
#include "util.h"
#include "tbf.h"

#ifdef BGP
#include "bgp.h"
#endif

// Globals
configt *config = NULL;       // all configuration
int tunfd = -1;               // tun interface file handle. (network device)
int udpfd = -1;               // UDP file handle
int controlfd = -1;           // Control signal handle
int clifd = -1;               // Socket listening for CLI connections.
int daefd = -1;               // Socket listening for DAE connections.
int snoopfd = -1;       // UDP file handle for sending out intercept data
int *radfds = NULL;           // RADIUS requests file handles
int ifrfd = -1;               // File descriptor for routing, etc
int ifr6fd = -1;        // File descriptor for IPv6 routing, etc
int rand_fd = -1;       // Random data source
int cluster_sockfd = -1;      // Intra-cluster communications socket.
int epollfd = -1;       // event polling
time_t basetime = 0;          // base clock
char hostname[1000] = "";     // us.
static int tunidx;            // ifr_ifindex of tun device
static int syslog_log = 0;    // are we logging to syslog
static FILE *log_stream = 0;  // file handle for direct logging (i.e. direct into file, not via syslog).
uint32_t last_id = 0;         // Unique ID for radius accounting

// calculated from config->l2tp_mtu
uint16_t MRU = 0;       // PPP MRU
uint16_t MSS = 0;       // TCP MSS

struct cli_session_actions *cli_session_actions = NULL;     // Pending session changes requested by CLI
struct cli_tunnel_actions *cli_tunnel_actions = NULL; // Pending tunnel changes required by CLI

static void *ip_hash[256];    // Mapping from IP address to session structures.
struct ipv6radix {
      int sess;
      struct ipv6radix *branch;
} ipv6_hash[256];       // Mapping from IPv6 address to session structures.

// Traffic counters.
static uint32_t udp_rx = 0, udp_rx_pkt = 0, udp_tx = 0;
static uint32_t eth_rx = 0, eth_rx_pkt = 0;
uint32_t eth_tx = 0;

static uint32_t ip_pool_size = 1;   // Size of the pool of addresses used for dynamic address allocation.
time_t time_now = 0;                // Current time in seconds since epoch.
static char time_now_string[64] = {0};    // Current time as a string.
static int time_changed = 0;        // time_now changed
char main_quit = 0;                 // True if we're in the process of exiting.
static char main_reload = 0;        // Re-load pending
linked_list *loaded_plugins;
linked_list *plugins[MAX_PLUGIN_TYPES];

#define membersize(STRUCT, MEMBER) sizeof(((STRUCT *)0)->MEMBER)
#define CONFIG(NAME, MEMBER, TYPE) { NAME, offsetof(configt, MEMBER), membersize(configt, MEMBER), TYPE }

config_descriptt config_values[] = {
      CONFIG("debug", debug, INT),
      CONFIG("log_file", log_filename, STRING),
      CONFIG("pid_file", pid_file, STRING),
      CONFIG("random_device", random_device, STRING),
      CONFIG("l2tp_secret", l2tp_secret, STRING),
      CONFIG("l2tp_mtu", l2tp_mtu, INT),
      CONFIG("ppp_restart_time", ppp_restart_time, INT),
      CONFIG("ppp_max_configure", ppp_max_configure, INT),
      CONFIG("ppp_max_failure", ppp_max_failure, INT),
      CONFIG("primary_dns", default_dns1, IPv4),
      CONFIG("secondary_dns", default_dns2, IPv4),
      CONFIG("primary_radius", radiusserver[0], IPv4),
      CONFIG("secondary_radius", radiusserver[1], IPv4),
      CONFIG("primary_radius_port", radiusport[0], SHORT),
      CONFIG("secondary_radius_port", radiusport[1], SHORT),
      CONFIG("radius_accounting", radius_accounting, BOOL),
      CONFIG("radius_interim", radius_interim, INT),
      CONFIG("radius_secret", radiussecret, STRING),
      CONFIG("radius_authtypes", radius_authtypes_s, STRING),
      CONFIG("radius_dae_port", radius_dae_port, SHORT),
      CONFIG("allow_duplicate_users", allow_duplicate_users, BOOL),
      CONFIG("bind_address", bind_address, IPv4),
      CONFIG("peer_address", peer_address, IPv4),
      CONFIG("send_garp", send_garp, BOOL),
      CONFIG("throttle_speed", rl_rate, UNSIGNED_LONG),
      CONFIG("throttle_buckets", num_tbfs, INT),
      CONFIG("accounting_dir", accounting_dir, STRING),
      CONFIG("setuid", target_uid, INT),
      CONFIG("dump_speed", dump_speed, BOOL),
      CONFIG("multi_read_count", multi_read_count, INT),
      CONFIG("scheduler_fifo", scheduler_fifo, BOOL),
      CONFIG("lock_pages", lock_pages, BOOL),
      CONFIG("icmp_rate", icmp_rate, INT),
      CONFIG("packet_limit", max_packets, INT),
      CONFIG("cluster_address", cluster_address, IPv4),
      CONFIG("cluster_interface", cluster_interface, STRING),
      CONFIG("cluster_mcast_ttl", cluster_mcast_ttl, INT),
      CONFIG("cluster_hb_interval", cluster_hb_interval, INT),
      CONFIG("cluster_hb_timeout", cluster_hb_timeout, INT),
      CONFIG("cluster_master_min_adv", cluster_master_min_adv, INT),
      CONFIG("ipv6_prefix", ipv6_prefix, IPv6),
      { NULL, 0, 0, 0 },
};

static char *plugin_functions[] = {
      NULL,
      "plugin_pre_auth",
      "plugin_post_auth",
      "plugin_packet_rx",
      "plugin_packet_tx",
      "plugin_timer",
      "plugin_new_session",
      "plugin_kill_session",
      "plugin_control",
      "plugin_radius_response",
      "plugin_radius_reset",
      "plugin_radius_account",
      "plugin_become_master",
      "plugin_new_session_master",
};

#define max_plugin_functions (sizeof(plugin_functions) / sizeof(char *))

// Counters for shutdown sessions
static sessiont shut_acct[8192];
static sessionidt shut_acct_n = 0;

tunnelt *tunnel = NULL;             // Array of tunnel structures.
sessiont *session = NULL;           // Array of session structures.
sessionlocalt *sess_local = NULL;   // Array of local per-session counters.
radiust *radius = NULL;             // Array of radius structures.
ippoolt *ip_address_pool = NULL;    // Array of dynamic IP addresses.
ip_filtert *ip_filters = NULL;            // Array of named filters.
static controlt *controlfree = 0;
struct Tstats *_statistics = NULL;
#ifdef RINGBUFFER
struct Tringbuffer *ringbuffer = NULL;
#endif

static void cache_ipmap(in_addr_t ip, int s);
static void uncache_ipmap(in_addr_t ip);
static void cache_ipv6map(struct in6_addr ip, int prefixlen, int s);
static void free_ip_address(sessionidt s);
static void dump_acct_info(int all);
static void sighup_handler(int sig);
static void shutdown_handler(int sig);
static void sigchild_handler(int sig);
static void build_chap_response(uint8_t *challenge, uint8_t id, uint16_t challenge_length, uint8_t **challenge_response);
static void update_config(void);
static void read_config_file(void);
static void initplugins(void);
static int add_plugin(char *plugin_name);
static int remove_plugin(char *plugin_name);
static void plugins_done(void);
static void processcontrol(uint8_t *buf, int len, struct sockaddr_in *addr, int alen, struct in_addr *local);
static tunnelidt new_tunnel(void);
static void unhide_value(uint8_t *value, size_t len, uint16_t type, uint8_t *vector, size_t vec_len);

// on slaves, alow BGP to withdraw cleanly before exiting
#define QUIT_DELAY      5

// quit actions (master)
#define QUIT_FAILOVER   1 // SIGTERM: exit when all control messages have been acked (for cluster failover)
#define QUIT_SHUTDOWN   2 // SIGQUIT: shutdown sessions/tunnels, reject new connections

// return internal time (10ths since process startup), set f if given
// as a side-effect sets time_now, and time_changed
static clockt now(double *f)
{
      struct timeval t;
      gettimeofday(&t, 0);
      if (f) *f = t.tv_sec + t.tv_usec / 1000000.0;
      if (t.tv_sec != time_now)
      {
          time_now = t.tv_sec;
          time_changed++;
      }
      return (t.tv_sec - basetime) * 10 + t.tv_usec / 100000 + 1;
}

// work out a retry time based on try number
// This is a straight bounded exponential backoff.
// Maximum re-try time is 32 seconds. (2^5).
clockt backoff(uint8_t try)
{
      if (try > 5) try = 5;                  // max backoff
      return now(NULL) + 10 * (1 << try);
}


//
// Log a debug message.  Typically called via the LOG macro
//
void _log(int level, sessionidt s, tunnelidt t, const char *format, ...)
{
      static char message[65536] = {0};
      va_list ap;

#ifdef RINGBUFFER
      if (ringbuffer)
      {
            if (++ringbuffer->tail >= RINGBUFFER_SIZE)
                  ringbuffer->tail = 0;
            if (ringbuffer->tail == ringbuffer->head)
                  if (++ringbuffer->head >= RINGBUFFER_SIZE)
                        ringbuffer->head = 0;

            ringbuffer->buffer[ringbuffer->tail].level = level;
            ringbuffer->buffer[ringbuffer->tail].session = s;
            ringbuffer->buffer[ringbuffer->tail].tunnel = t;
            va_start(ap, format);
            vsnprintf(ringbuffer->buffer[ringbuffer->tail].message, 4095, format, ap);
            va_end(ap);
      }
#endif

      if (config->debug < level) return;

      va_start(ap, format);
      vsnprintf(message, sizeof(message), format, ap);

      if (log_stream)
            fprintf(log_stream, "%s %02d/%02d %s", time_now_string, t, s, message);
      else if (syslog_log)
            syslog(level + 2, "%02d/%02d %s", t, s, message); // We don't need LOG_EMERG or LOG_ALERT

      va_end(ap);
}

void _log_hex(int level, const char *title, const uint8_t *data, int maxsize)
{
      int i, j;
      const uint8_t *d = data;

      if (config->debug < level) return;

      // No support for _log_hex to syslog
      if (log_stream)
      {
            _log(level, 0, 0, "%s (%d bytes):\n", title, maxsize);
            setvbuf(log_stream, NULL, _IOFBF, 16384);

            for (i = 0; i < maxsize; )
            {
                  fprintf(log_stream, "%4X: ", i);
                  for (j = i; j < maxsize && j < (i + 16); j++)
                  {
                        fprintf(log_stream, "%02X ", d[j]);
                        if (j == i + 7)
                              fputs(": ", log_stream);
                  }

                  for (; j < i + 16; j++)
                  {
                        fputs("   ", log_stream);
                        if (j == i + 7)
                              fputs(": ", log_stream);
                  }

                  fputs("  ", log_stream);
                  for (j = i; j < maxsize && j < (i + 16); j++)
                  {
                        if (d[j] >= 0x20 && d[j] < 0x7f && d[j] != 0x20)
                              fputc(d[j], log_stream);
                        else
                              fputc('.', log_stream);

                        if (j == i + 7)
                              fputs("  ", log_stream);
                  }

                  i = j;
                  fputs("\n", log_stream);
            }

            fflush(log_stream);
            setbuf(log_stream, NULL);
      }
}

// update a counter, accumulating 2^32 wraps
void increment_counter(uint32_t *counter, uint32_t *wrap, uint32_t delta)
{
      uint32_t new = *counter + delta;
      if (new < *counter)
            (*wrap)++;

      *counter = new;
}

// initialise the random generator
static void initrandom(char *source)
{
      static char path[sizeof(config->random_device)] = "*undefined*";

      // reinitialise only if we are forced to do so or if the config has changed
      if (source && !strncmp(path, source, sizeof(path)))
            return;

      // close previous source, if any
      if (rand_fd >= 0)
            close(rand_fd);

      rand_fd = -1;

      if (source)
      {
            // register changes
            snprintf(path, sizeof(path), "%s", source);

            if (*path == '/')
            {
                  rand_fd = open(path, O_RDONLY|O_NONBLOCK);
                  if (rand_fd < 0)
                        LOG(0, 0, 0, "Error opening the random device %s: %s\n",
                              path, strerror(errno));
            }
      }
}

// fill buffer with random data
void random_data(uint8_t *buf, int len)
{
      int n = 0;

      CSTAT(random_data);
      if (rand_fd >= 0)
      {
            n = read(rand_fd, buf, len);
            if (n >= len) return;
            if (n < 0)
            {
                  if (errno != EAGAIN)
                  {
                        LOG(0, 0, 0, "Error reading from random source: %s\n",
                              strerror(errno));

                        // fall back to rand()
                        initrandom(NULL);
                  }

                  n = 0;
            }
      }

      // append missing data
      while (n < len)
            // not using the low order bits from the prng stream
            buf[n++] = (rand() >> 4) & 0xff;
}

// Add a route
//
// This adds it to the routing table, advertises it
// via BGP if enabled, and stuffs it into the
// 'sessionbyip' cache.
//
// 'ip' and 'mask' must be in _host_ order.
//
static void routeset(sessionidt s, in_addr_t ip, in_addr_t mask, in_addr_t gw, int add)
{
      struct rtentry r;
      int i;

      if (!mask) mask = 0xffffffff;

      ip &= mask;       // Force the ip to be the first one in the route.

      memset(&r, 0, sizeof(r));
      r.rt_dev = config->tundevice;
      r.rt_dst.sa_family = AF_INET;
      *(uint32_t *) & (((struct sockaddr_in *) &r.rt_dst)->sin_addr.s_addr) = htonl(ip);
      r.rt_gateway.sa_family = AF_INET;
      *(uint32_t *) & (((struct sockaddr_in *) &r.rt_gateway)->sin_addr.s_addr) = htonl(gw);
      r.rt_genmask.sa_family = AF_INET;
      *(uint32_t *) & (((struct sockaddr_in *) &r.rt_genmask)->sin_addr.s_addr) = htonl(mask);
      r.rt_flags = (RTF_UP | RTF_STATIC);
      if (gw)
            r.rt_flags |= RTF_GATEWAY;
      else if (mask == 0xffffffff)
            r.rt_flags |= RTF_HOST;

      LOG(1, s, 0, "Route %s %s/%s%s%s\n", add ? "add" : "del",
          fmtaddr(htonl(ip), 0), fmtaddr(htonl(mask), 1),
          gw ? " via" : "", gw ? fmtaddr(htonl(gw), 2) : "");

      if (ioctl(ifrfd, add ? SIOCADDRT : SIOCDELRT, (void *) &r) < 0)
            LOG(0, 0, 0, "routeset() error in ioctl: %s\n", strerror(errno));

#ifdef BGP
      if (add)
            bgp_add_route(htonl(ip), htonl(mask));
      else
            bgp_del_route(htonl(ip), htonl(mask));
#endif /* BGP */

            // Add/Remove the IPs to the 'sessionbyip' cache.
            // Note that we add the zero address in the case of
            // a network route. Roll on CIDR.

            // Note that 's == 0' implies this is the address pool.
            // We still cache it here, because it will pre-fill
            // the malloc'ed tree.

      if (s)
      {
            if (!add)   // Are we deleting a route?
                  s = 0;      // Caching the session as '0' is the same as uncaching.

            for (i = ip; (i&mask) == (ip&mask) ; ++i)
                  cache_ipmap(i, s);
      }
}

void route6set(sessionidt s, struct in6_addr ip, int prefixlen, int add)
{
      struct in6_rtmsg rt;
      char ipv6addr[INET6_ADDRSTRLEN];

      if (ifr6fd < 0)
      {
            LOG(0, 0, 0, "Asked to set IPv6 route, but IPv6 not setup.\n");
            return;
      }

      memset(&rt, 0, sizeof(rt));

      memcpy(&rt.rtmsg_dst, &ip, sizeof(struct in6_addr));
      rt.rtmsg_dst_len = prefixlen;
      rt.rtmsg_metric = 1;
      rt.rtmsg_flags = RTF_UP;
      rt.rtmsg_ifindex = tunidx;

      LOG(1, 0, 0, "Route %s %s/%d\n",
          add ? "add" : "del",
          inet_ntop(AF_INET6, &ip, ipv6addr, INET6_ADDRSTRLEN),
          prefixlen);

      if (ioctl(ifr6fd, add ? SIOCADDRT : SIOCDELRT, (void *) &rt) < 0)
            LOG(0, 0, 0, "route6set() error in ioctl: %s\n",
                        strerror(errno));

      // FIXME: need to add BGP routing (RFC2858)

      if (s)
      {
            if (!add)   // Are we deleting a route?
                  s = 0;      // Caching the session as '0' is the same as uncaching.

            cache_ipv6map(ip, prefixlen, s);
      }
      
      return;
}

// defined in linux/ipv6.h, but tricky to include from user-space
// TODO: move routing to use netlink rather than ioctl
struct in6_ifreq {
      struct in6_addr ifr6_addr;
      __u32 ifr6_prefixlen;
      unsigned int ifr6_ifindex;
};

//
// Set up TUN interface
static void inittun(void)
{
      struct ifreq ifr;
      struct in6_ifreq ifr6;
      struct sockaddr_in sin = {0};
      memset(&ifr, 0, sizeof(ifr));
      ifr.ifr_flags = IFF_TUN;

      tunfd = open(TUNDEVICE, O_RDWR);
      if (tunfd < 0)
      {                          // fatal
            LOG(0, 0, 0, "Can't open %s: %s\n", TUNDEVICE, strerror(errno));
            exit(1);
      }
      {
            int flags = fcntl(tunfd, F_GETFL, 0);
            fcntl(tunfd, F_SETFL, flags | O_NONBLOCK);
      }
      if (ioctl(tunfd, TUNSETIFF, (void *) &ifr) < 0)
      {
            LOG(0, 0, 0, "Can't set tun interface: %s\n", strerror(errno));
            exit(1);
      }
      assert(strlen(ifr.ifr_name) < sizeof(config->tundevice));
      strncpy(config->tundevice, ifr.ifr_name, sizeof(config->tundevice) - 1);
      ifrfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);

      sin.sin_family = AF_INET;
      sin.sin_addr.s_addr = config->bind_address ? config->bind_address : 0x01010101; // 1.1.1.1
      memcpy(&ifr.ifr_addr, &sin, sizeof(struct sockaddr));

      if (ioctl(ifrfd, SIOCSIFADDR, (void *) &ifr) < 0)
      {
            LOG(0, 0, 0, "Error setting tun address: %s\n", strerror(errno));
            exit(1);
      }
      /* Bump up the qlen to deal with bursts from the network */
      ifr.ifr_qlen = 1000;
      if (ioctl(ifrfd, SIOCSIFTXQLEN, (void *) &ifr) < 0)
      {
            LOG(0, 0, 0, "Error setting tun queue length: %s\n", strerror(errno));
            exit(1);
      }
      /* set MTU to modem MRU */
      ifr.ifr_mtu = MRU;
      if (ioctl(ifrfd, SIOCSIFMTU, (void *) &ifr) < 0)
      {
            LOG(0, 0, 0, "Error setting tun MTU: %s\n", strerror(errno));
            exit(1);
      }
      ifr.ifr_flags = IFF_UP;
      if (ioctl(ifrfd, SIOCSIFFLAGS, (void *) &ifr) < 0)
      {
            LOG(0, 0, 0, "Error setting tun flags: %s\n", strerror(errno));
            exit(1);
      }
      if (ioctl(ifrfd, SIOCGIFINDEX, (void *) &ifr) < 0)
      {
            LOG(0, 0, 0, "Error getting tun ifindex: %s\n", strerror(errno));
            exit(1);
      }
      tunidx = ifr.ifr_ifindex;

      // Only setup IPv6 on the tun device if we have a configured prefix
      if (config->ipv6_prefix.s6_addr[0]) {
            ifr6fd = socket(PF_INET6, SOCK_DGRAM, 0);

            // Link local address is FE80::1
            memset(&ifr6.ifr6_addr, 0, sizeof(ifr6.ifr6_addr));
            ifr6.ifr6_addr.s6_addr[0] = 0xFE;
            ifr6.ifr6_addr.s6_addr[1] = 0x80;
            ifr6.ifr6_addr.s6_addr[15] = 1;
            ifr6.ifr6_prefixlen = 64;
            ifr6.ifr6_ifindex = ifr.ifr_ifindex;
            if (ioctl(ifr6fd, SIOCSIFADDR, (void *) &ifr6) < 0)
            {
                  LOG(0, 0, 0, "Error setting tun IPv6 link local address:"
                        " %s\n", strerror(errno));
            }

            // Global address is prefix::1
            memset(&ifr6.ifr6_addr, 0, sizeof(ifr6.ifr6_addr));
            ifr6.ifr6_addr = config->ipv6_prefix;
            ifr6.ifr6_addr.s6_addr[15] = 1;
            ifr6.ifr6_prefixlen = 64;
            ifr6.ifr6_ifindex = ifr.ifr_ifindex;
            if (ioctl(ifr6fd, SIOCSIFADDR, (void *) &ifr6) < 0)
            {
                  LOG(0, 0, 0, "Error setting tun IPv6 global address: %s\n",
                        strerror(errno));
            }
      }
}

// set up UDP ports
static void initudp(void)
{
      int on = 1;
      struct sockaddr_in addr;

      // Tunnel
      memset(&addr, 0, sizeof(addr));
      addr.sin_family = AF_INET;
      addr.sin_port = htons(L2TPPORT);
      addr.sin_addr.s_addr = config->bind_address;
      udpfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
      setsockopt(udpfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
      {
            int flags = fcntl(udpfd, F_GETFL, 0);
            fcntl(udpfd, F_SETFL, flags | O_NONBLOCK);
      }
      if (bind(udpfd, (void *) &addr, sizeof(addr)) < 0)
      {
            LOG(0, 0, 0, "Error in UDP bind: %s\n", strerror(errno));
            exit(1);
      }

      // Control
      memset(&addr, 0, sizeof(addr));
      addr.sin_family = AF_INET;
      addr.sin_port = htons(NSCTL_PORT);
      controlfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
      setsockopt(controlfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
      setsockopt(controlfd, SOL_IP, IP_PKTINFO, &on, sizeof(on)); // recvfromto
      if (bind(controlfd, (void *) &addr, sizeof(addr)) < 0)
      {
            LOG(0, 0, 0, "Error in control bind: %s\n", strerror(errno));
            exit(1);
      }

      // Dynamic Authorization Extensions to RADIUS
      memset(&addr, 0, sizeof(addr));
      addr.sin_family = AF_INET;
      addr.sin_port = htons(config->radius_dae_port);
      daefd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
      setsockopt(daefd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
      setsockopt(daefd, SOL_IP, IP_PKTINFO, &on, sizeof(on)); // recvfromto
      if (bind(daefd, (void *) &addr, sizeof(addr)) < 0)
      {
            LOG(0, 0, 0, "Error in DAE bind: %s\n", strerror(errno));
            exit(1);
      }

      // Intercept
      snoopfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
}

//
// Find session by IP, < 1 for not found
//
// Confusingly enough, this 'ip' must be
// in _network_ order. This being the common
// case when looking it up from IP packet headers.
//
// We actually use this cache for two things.
// #1. For used IP addresses, this maps to the
// session ID that it's used by.
// #2. For un-used IP addresses, this maps to the
// index into the pool table that contains that
// IP address.
//

static int lookup_ipmap(in_addr_t ip)
{
      uint8_t *a = (uint8_t *) &ip;
      uint8_t **d = (uint8_t **) ip_hash;

      if (!(d = (uint8_t **) d[(size_t) *a++])) return 0;
      if (!(d = (uint8_t **) d[(size_t) *a++])) return 0;
      if (!(d = (uint8_t **) d[(size_t) *a++])) return 0;

      return (int) (intptr_t) d[(size_t) *a];
}

static int lookup_ipv6map(struct in6_addr ip)
{
      struct ipv6radix *curnode;
      int i;
      int s;
      char ipv6addr[INET6_ADDRSTRLEN];

      curnode = &ipv6_hash[ip.s6_addr[0]];
      i = 1;
      s = curnode->sess;

      while (s == 0 && i < 15 && curnode->branch != NULL)
      {
            curnode = &curnode->branch[ip.s6_addr[i]];
            s = curnode->sess;
            i++;
      }

      LOG(4, s, session[s].tunnel, "Looking up address %s and got %d\n",
                  inet_ntop(AF_INET6, &ip, ipv6addr,
                        INET6_ADDRSTRLEN),
                  s);

      return s;
}

sessionidt sessionbyip(in_addr_t ip)
{
      int s = lookup_ipmap(ip);
      CSTAT(sessionbyip);

      if (s > 0 && s < MAXSESSION && session[s].opened)
            return (sessionidt) s;

      return 0;
}

sessionidt sessionbyipv6(struct in6_addr ip)
{
      int s;
      CSTAT(sessionbyipv6);

      if (!memcmp(&config->ipv6_prefix, &ip, 8) ||
            (ip.s6_addr[0] == 0xFE &&
             ip.s6_addr[1] == 0x80 &&
             ip.s6_addr16[1] == 0 &&
             ip.s6_addr16[2] == 0 &&
             ip.s6_addr16[3] == 0)) {
            s = lookup_ipmap(*(in_addr_t *) &ip.s6_addr[8]);
      } else {
            s = lookup_ipv6map(ip);
      }

      if (s > 0 && s < MAXSESSION && session[s].opened)
            return s;

      return 0;
}

//
// Take an IP address in HOST byte order and
// add it to the sessionid by IP cache.
//
// (It's actually cached in network order)
//
static void cache_ipmap(in_addr_t ip, int s)
{
      in_addr_t nip = htonl(ip);    // MUST be in network order. I.e. MSB must in be ((char *) (&ip))[0]
      uint8_t *a = (uint8_t *) &nip;
      uint8_t **d = (uint8_t **) ip_hash;
      int i;

      for (i = 0; i < 3; i++)
      {
            if (!d[(size_t) a[i]])
            {
                  if (!(d[(size_t) a[i]] = calloc(256, sizeof(void *))))
                        return;
            }

            d = (uint8_t **) d[(size_t) a[i]];
      }

      d[(size_t) a[3]] = (uint8_t *) (intptr_t) s;

      if (s > 0)
            LOG(4, s, session[s].tunnel, "Caching ip address %s\n", fmtaddr(nip, 0));

      else if (s == 0)
            LOG(4, 0, 0, "Un-caching ip address %s\n", fmtaddr(nip, 0));
      // else a map to an ip pool index.
}

static void uncache_ipmap(in_addr_t ip)
{
      cache_ipmap(ip, 0);     // Assign it to the NULL session.
}

static void cache_ipv6map(struct in6_addr ip, int prefixlen, int s)
{
      int i;
      int bytes;
      struct ipv6radix *curnode;
      char ipv6addr[INET6_ADDRSTRLEN];

      curnode = &ipv6_hash[ip.s6_addr[0]];

      bytes = prefixlen >> 3;
      i = 1;
      while (i < bytes) {
            if (curnode->branch == NULL)
            {
                  if (!(curnode->branch = calloc(256,
                              sizeof (struct ipv6radix))))
                        return;
            }
            curnode = &curnode->branch[ip.s6_addr[i]];
            i++;
      }

      curnode->sess = s;

      if (s > 0)
            LOG(4, s, session[s].tunnel, "Caching ip address %s/%d\n",
                        inet_ntop(AF_INET6, &ip, ipv6addr, 
                              INET6_ADDRSTRLEN),
                        prefixlen);
      else if (s == 0)
            LOG(4, 0, 0, "Un-caching ip address %s/%d\n",
                        inet_ntop(AF_INET6, &ip, ipv6addr, 
                              INET6_ADDRSTRLEN),
                        prefixlen);
}

//
// CLI list to dump current ipcache.
//
int cmd_show_ipcache(struct cli_def *cli, char *command, char **argv, int argc)
{
      char **d = (char **) ip_hash, **e, **f, **g;
      int i, j, k, l;
      int count = 0;

      if (CLI_HELP_REQUESTED)
            return CLI_HELP_NO_ARGS;

      cli_print(cli, "%7s %s", "Sess#", "IP Address");

      for (i = 0; i < 256; ++i)
      {
            if (!d[i])
                  continue;
            e = (char **) d[i];
            for (j = 0; j < 256; ++j)
            {
                  if (!e[j])
                        continue;
                  f = (char **) e[j];
                  for (k = 0; k < 256; ++k)
                  {
                        if (!f[k])
                              continue;
                        g = (char **)f[k];
                        for (l = 0; l < 256; ++l)
                        {
                              if (!g[l])
                                    continue;
                              cli_print(cli, "%7d %d.%d.%d.%d", (int) (intptr_t) g[l], i, j, k, l);
                              ++count;
                        }
                  }
            }
      }
      cli_print(cli, "%d entries in cache", count);
      return CLI_OK;
}


// Find session by username, 0 for not found
// walled garden users aren't authenticated, so the username is
// reasonably useless. Ignore them to avoid incorrect actions
//
// This is VERY inefficent. Don't call it often. :)
//
sessionidt sessionbyuser(char *username)
{
      int s;
      CSTAT(sessionbyuser);

      for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
      {
            if (!session[s].opened)
                  continue;

            if (session[s].walled_garden)
                  continue;         // Skip walled garden users.

            if (!strncmp(session[s].user, username, 128))
                  return s;

      }
      return 0;   // Not found.
}

void send_garp(in_addr_t ip)
{
      int s;
      struct ifreq ifr;
      uint8_t mac[6];

      s = socket(PF_INET, SOCK_DGRAM, 0);
      if (s < 0)
      {
            LOG(0, 0, 0, "Error creating socket for GARP: %s\n", strerror(errno));
            return;
      }
      memset(&ifr, 0, sizeof(ifr));
      strncpy(ifr.ifr_name, "eth0", sizeof(ifr.ifr_name) - 1);
      if (ioctl(s, SIOCGIFHWADDR, &ifr) < 0)
      {
            LOG(0, 0, 0, "Error getting eth0 hardware address for GARP: %s\n", strerror(errno));
            close(s);
            return;
      }
      memcpy(mac, &ifr.ifr_hwaddr.sa_data, 6*sizeof(char));
      if (ioctl(s, SIOCGIFINDEX, &ifr) < 0)
      {
            LOG(0, 0, 0, "Error getting eth0 interface index for GARP: %s\n", strerror(errno));
            close(s);
            return;
      }
      close(s);
      sendarp(ifr.ifr_ifindex, mac, ip);
}

static sessiont *sessiontbysessionidt(sessionidt s)
{
      if (!s || s >= MAXSESSION) return NULL;
      return &session[s];
}

static sessionidt sessionidtbysessiont(sessiont *s)
{
      sessionidt val = s-session;
      if (s < session || val >= MAXSESSION) return 0;
      return val;
}

// actually send a control message for a specific tunnel
void tunnelsend(uint8_t * buf, uint16_t l, tunnelidt t)
{
      struct sockaddr_in addr;

      CSTAT(tunnelsend);

      if (!t)
      {
            LOG(0, 0, t, "tunnelsend called with 0 as tunnel id\n");
            STAT(tunnel_tx_errors);
            return;
      }

      if (!tunnel[t].ip)
      {
            LOG(1, 0, t, "Error sending data out tunnel: no remote endpoint (tunnel not set up)\n");
            STAT(tunnel_tx_errors);
            return;
      }

      memset(&addr, 0, sizeof(addr));
      addr.sin_family = AF_INET;
      *(uint32_t *) & addr.sin_addr = htonl(tunnel[t].ip);
      addr.sin_port = htons(tunnel[t].port);

      // sequence expected, if sequence in message
      if (*buf & 0x08) *(uint16_t *) (buf + ((*buf & 0x40) ? 10 : 8)) = htons(tunnel[t].nr);

      // If this is a control message, deal with retries
      if (*buf & 0x80)
      {
            tunnel[t].last = time_now; // control message sent
            tunnel[t].retry = backoff(tunnel[t].try); // when to resend
            if (tunnel[t].try)
            {
                  STAT(tunnel_retries);
                  LOG(3, 0, t, "Control message resend try %d\n", tunnel[t].try);
            }
      }

      if (sendto(udpfd, buf, l, 0, (void *) &addr, sizeof(addr)) < 0)
      {
            LOG(0, ntohs((*(uint16_t *) (buf + 6))), t, "Error sending data out tunnel: %s (udpfd=%d, buf=%p, len=%d, dest=%s)\n",
                        strerror(errno), udpfd, buf, l, inet_ntoa(addr.sin_addr));
            STAT(tunnel_tx_errors);
            return;
      }

      LOG_HEX(5, "Send Tunnel Data", buf, l);
      STAT(tunnel_tx_packets);
      INC_STAT(tunnel_tx_bytes, l);
}

//
// Tiny helper function to write data to
// the 'tun' device.
//
int tun_write(uint8_t * data, int size)
{
      return write(tunfd, data, size);
}

// adjust tcp mss to avoid fragmentation (called only for tcp packets with syn set)
void adjust_tcp_mss(sessionidt s, tunnelidt t, uint8_t *buf, int len, uint8_t *tcp)
{
      int d = (tcp[12] >> 4) * 4;
      uint8_t *mss = 0;
      uint8_t *opts;
      uint8_t *data;
      uint16_t orig;
      uint32_t sum;

      if ((tcp[13] & 0x3f) & ~(TCP_FLAG_SYN|TCP_FLAG_ACK)) // only want SYN and SYN,ACK
            return;

      if (tcp + d > buf + len) // short?
            return;

      opts = tcp + 20;
      data = tcp + d;

      while (opts < data)
      {
            if (*opts == 2 && opts[1] == 4) // mss option (2), length 4
            {
                  mss = opts + 2;
                  if (mss + 2 > data) return; // short?
                  break;
            }

            if (*opts == 0) return; // end of options
            if (*opts == 1 || !opts[1]) // no op (one byte), or no length (prevent loop)
                  opts++;
            else
                  opts += opts[1]; // skip over option
      }

      if (!mss) return; // not found
      orig = ntohs(*(uint16_t *) mss);

      if (orig <= MSS) return; // mss OK

      LOG(5, s, t, "TCP: %s:%u -> %s:%u SYN%s: adjusted mss from %u to %u\n",
            fmtaddr(*(in_addr_t *) (buf + 12), 0), ntohs(*(uint16_t *) tcp),
            fmtaddr(*(in_addr_t *) (buf + 16), 1), ntohs(*(uint16_t *) (tcp + 2)),
            (tcp[13] & TCP_FLAG_ACK) ? ",ACK" : "", orig, MSS);

      // set mss
      *(int16_t *) mss = htons(MSS);

      // adjust checksum (see rfc1141)
      sum = orig + (~MSS & 0xffff);
      sum += ntohs(*(uint16_t *) (tcp + 16));
      sum = (sum & 0xffff) + (sum >> 16);
      *(uint16_t *) (tcp + 16) = htons(sum + (sum >> 16));
}

// process outgoing (to tunnel) IP
//
static void processipout(uint8_t *buf, int len)
{
      sessionidt s;
      sessiont *sp;
      tunnelidt t;
      in_addr_t ip;

      uint8_t *data = buf;    // Keep a copy of the originals.
      int size = len;

      uint8_t b[MAXETHER + 20];

      CSTAT(processipout);

      if (len < MIN_IP_SIZE)
      {
            LOG(1, 0, 0, "Short IP, %d bytes\n", len);
            STAT(tun_rx_errors);
            return;
      }
      if (len >= MAXETHER)
      {
            LOG(1, 0, 0, "Oversize IP packet %d bytes\n", len);
            STAT(tun_rx_errors);
            return;
      }

      // Skip the tun header
      buf += 4;
      len -= 4;

      // Got an IP header now
      if (*(uint8_t *)(buf) >> 4 != 4)
      {
            LOG(1, 0, 0, "IP: Don't understand anything except IPv4\n");
            return;
      }

      ip = *(uint32_t *)(buf + 16);
      if (!(s = sessionbyip(ip)))
      {
            // Is this a packet for a session that doesn't exist?
            static int rate = 0;    // Number of ICMP packets we've sent this second.
            static int last = 0;    // Last time we reset the ICMP packet counter 'rate'.

            if (last != time_now)
            {
                  last = time_now;
                  rate = 0;
            }

            if (rate++ < config->icmp_rate) // Only send a max of icmp_rate per second.
            {
                  LOG(4, 0, 0, "IP: Sending ICMP host unreachable to %s\n", fmtaddr(*(in_addr_t *)(buf + 12), 0));
                  host_unreachable(*(in_addr_t *)(buf + 12), *(uint16_t *)(buf + 4),
                        config->bind_address ? config->bind_address : my_address, buf, len);
            }
            return;
      }
      t = session[s].tunnel;
      sp = &session[s];

      // DoS prevention: enforce a maximum number of packets per 0.1s for a session
      if (config->max_packets > 0)
      {
            if (sess_local[s].last_packet_out == TIME)
            {
                  int max = config->max_packets;

                  // All packets for throttled sessions are handled by the
                  // master, so further limit by using the throttle rate.
                  // A bit of a kludge, since throttle rate is in kbps,
                  // but should still be generous given our average DSL
                  // packet size is 200 bytes: a limit of 28kbps equates
                  // to around 180 packets per second.
                  if (!config->cluster_iam_master && sp->throttle_out && sp->throttle_out < max)
                        max = sp->throttle_out;

                  if (++sess_local[s].packets_out > max)
                  {
                        sess_local[s].packets_dropped++;
                        return;
                  }
            }
            else
            {
                  if (sess_local[s].packets_dropped)
                  {
                        INC_STAT(tun_rx_dropped, sess_local[s].packets_dropped);
                        LOG(3, s, t, "Dropped %u/%u packets to %s for %suser %s\n",
                              sess_local[s].packets_dropped, sess_local[s].packets_out,
                              fmtaddr(ip, 0), sp->throttle_out ? "throttled " : "",
                              sp->user);
                  }

                  sess_local[s].last_packet_out = TIME;
                  sess_local[s].packets_out = 1;
                  sess_local[s].packets_dropped = 0;
            }
      }

      // run access-list if any
      if (session[s].filter_out && !ip_filter(buf, len, session[s].filter_out - 1))
            return;

      // adjust MSS on SYN and SYN,ACK packets with options
      if ((ntohs(*(uint16_t *) (buf + 6)) & 0x1fff) == 0 && buf[9] == IPPROTO_TCP) // first tcp fragment
      {
            int ihl = (buf[0] & 0xf) * 4; // length of IP header
            if (len >= ihl + 20 && (buf[ihl + 13] & TCP_FLAG_SYN) && ((buf[ihl + 12] >> 4) > 5))
                  adjust_tcp_mss(s, t, buf, len, buf + ihl);
      }

      if (sp->tbf_out)
      {
            // Are we throttling this session?
            if (config->cluster_iam_master)
                  tbf_queue_packet(sp->tbf_out, data, size);
            else
                  master_throttle_packet(sp->tbf_out, data, size);
            return;
      }

      if (sp->walled_garden && !config->cluster_iam_master)
      {
            // We are walled-gardening this
            master_garden_packet(s, data, size);
            return;
      }

      LOG(5, s, t, "Ethernet -> Tunnel (%d bytes)\n", len);

      // Add on L2TP header
      {
            uint8_t *p = makeppp(b, sizeof(b), buf, len, s, t, PPPIP);
            if (!p) return;
            tunnelsend(b, len + (p-b), t); // send it...
      }

      // Snooping this session, send it to intercept box
      if (sp->snoop_ip && sp->snoop_port)
            snoop_send_packet(buf, len, sp->snoop_ip, sp->snoop_port);

      increment_counter(&sp->cout, &sp->cout_wrap, len); // byte count
      sp->cout_delta += len;
      sp->pout++;
      udp_tx += len;

      sess_local[s].cout += len;    // To send to master..
      sess_local[s].pout++;
}

// process outgoing (to tunnel) IPv6
//
static void processipv6out(uint8_t * buf, int len)
{
      sessionidt s;
      sessiont *sp;
      tunnelidt t;
      in_addr_t ip;
      struct in6_addr ip6;

      uint8_t *data = buf;    // Keep a copy of the originals.
      int size = len;

      uint8_t b[MAXETHER + 20];

      CSTAT(processipv6out);

      if (len < MIN_IP_SIZE)
      {
            LOG(1, 0, 0, "Short IPv6, %d bytes\n", len);
            STAT(tunnel_tx_errors);
            return;
      }
      if (len >= MAXETHER)
      {
            LOG(1, 0, 0, "Oversize IPv6 packet %d bytes\n", len);
            STAT(tunnel_tx_errors);
            return;
      }

      // Skip the tun header
      buf += 4;
      len -= 4;

      // Got an IP header now
      if (*(uint8_t *)(buf) >> 4 != 6)
      {
            LOG(1, 0, 0, "IP: Don't understand anything except IPv6\n");
            return;
      }

      ip6 = *(struct in6_addr *)(buf+24);
      s = sessionbyipv6(ip6);

      if (s == 0)
      {
            ip = *(uint32_t *)(buf + 32);
            s = sessionbyip(ip);
      }
      
      if (s == 0)
      {
            // Is this a packet for a session that doesn't exist?
            static int rate = 0;    // Number of ICMP packets we've sent this second.
            static int last = 0;    // Last time we reset the ICMP packet counter 'rate'.

            if (last != time_now)
            {
                  last = time_now;
                  rate = 0;
            }

            if (rate++ < config->icmp_rate) // Only send a max of icmp_rate per second.
            {
                  // FIXME: Should send icmp6 host unreachable
            }
            return;
      }
      t = session[s].tunnel;
      sp = &session[s];

      // FIXME: add DoS prevention/filters?

      if (sp->tbf_out)
      {
            // Are we throttling this session?
            if (config->cluster_iam_master)
                  tbf_queue_packet(sp->tbf_out, data, size);
            else
                  master_throttle_packet(sp->tbf_out, data, size);
            return;
      }
      else if (sp->walled_garden && !config->cluster_iam_master)
      {
            // We are walled-gardening this
            master_garden_packet(s, data, size);
            return;
      }

      LOG(5, s, t, "Ethernet -> Tunnel (%d bytes)\n", len);

      // Add on L2TP header
      {
            uint8_t *p = makeppp(b, sizeof(b), buf, len, s, t, PPPIPV6);
            if (!p) return;
            tunnelsend(b, len + (p-b), t); // send it...
      }

      // Snooping this session, send it to intercept box
      if (sp->snoop_ip && sp->snoop_port)
            snoop_send_packet(buf, len, sp->snoop_ip, sp->snoop_port);

      increment_counter(&sp->cout, &sp->cout_wrap, len); // byte count
      sp->cout_delta += len;
      sp->pout++;
      udp_tx += len;

      sess_local[s].cout += len;    // To send to master..
      sess_local[s].pout++;
}

//
// Helper routine for the TBF filters.
// Used to send queued data in to the user!
//
static void send_ipout(sessionidt s, uint8_t *buf, int len)
{
      sessiont *sp;
      tunnelidt t;
      in_addr_t ip;

      uint8_t b[MAXETHER + 20];

      if (len < 0 || len > MAXETHER)
      {
            LOG(1, 0, 0, "Odd size IP packet: %d bytes\n", len);
            return;
      }

      // Skip the tun header
      buf += 4;
      len -= 4;

      ip = *(in_addr_t *)(buf + 16);

      if (!session[s].ip)
            return;

      t = session[s].tunnel;
      sp = &session[s];

      LOG(5, s, t, "Ethernet -> Tunnel (%d bytes)\n", len);

      // Add on L2TP header
      {
            uint8_t *p = makeppp(b, sizeof(b), buf, len, s, t, PPPIP);
            if (!p) return;
            tunnelsend(b, len + (p-b), t); // send it...
      }

      // Snooping this session.
      if (sp->snoop_ip && sp->snoop_port)
            snoop_send_packet(buf, len, sp->snoop_ip, sp->snoop_port);

      increment_counter(&sp->cout, &sp->cout_wrap, len); // byte count
      sp->cout_delta += len;
      sp->pout++;
      udp_tx += len;

      sess_local[s].cout += len;    // To send to master..
      sess_local[s].pout++;
}

// add an AVP (16 bit)
static void control16(controlt * c, uint16_t avp, uint16_t val, uint8_t m)
{
      uint16_t l = (m ? 0x8008 : 0x0008);
      *(uint16_t *) (c->buf + c->length + 0) = htons(l);
      *(uint16_t *) (c->buf + c->length + 2) = htons(0);
      *(uint16_t *) (c->buf + c->length + 4) = htons(avp);
      *(uint16_t *) (c->buf + c->length + 6) = htons(val);
      c->length += 8;
}

// add an AVP (32 bit)
static void control32(controlt * c, uint16_t avp, uint32_t val, uint8_t m)
{
      uint16_t l = (m ? 0x800A : 0x000A);
      *(uint16_t *) (c->buf + c->length + 0) = htons(l);
      *(uint16_t *) (c->buf + c->length + 2) = htons(0);
      *(uint16_t *) (c->buf + c->length + 4) = htons(avp);
      *(uint32_t *) (c->buf + c->length + 6) = htonl(val);
      c->length += 10;
}

// add an AVP (string)
static void controls(controlt * c, uint16_t avp, char *val, uint8_t m)
{
      uint16_t l = ((m ? 0x8000 : 0) + strlen(val) + 6);
      *(uint16_t *) (c->buf + c->length + 0) = htons(l);
      *(uint16_t *) (c->buf + c->length + 2) = htons(0);
      *(uint16_t *) (c->buf + c->length + 4) = htons(avp);
      memcpy(c->buf + c->length + 6, val, strlen(val));
      c->length += 6 + strlen(val);
}

// add a binary AVP
static void controlb(controlt * c, uint16_t avp, uint8_t *val, unsigned int len, uint8_t m)
{
      uint16_t l = ((m ? 0x8000 : 0) + len + 6);
      *(uint16_t *) (c->buf + c->length + 0) = htons(l);
      *(uint16_t *) (c->buf + c->length + 2) = htons(0);
      *(uint16_t *) (c->buf + c->length + 4) = htons(avp);
      memcpy(c->buf + c->length + 6, val, len);
      c->length += 6 + len;
}

// new control connection
static controlt *controlnew(uint16_t mtype)
{
      controlt *c;
      if (!controlfree)
            c = malloc(sizeof(controlt));
      else
      {
            c = controlfree;
            controlfree = c->next;
      }
      assert(c);
      c->next = 0;
      *(uint16_t *) (c->buf + 0) = htons(0xC802); // flags/ver
      c->length = 12;
      control16(c, 0, mtype, 1);
      return c;
}

// send zero block if nothing is waiting
// (ZLB send).
static void controlnull(tunnelidt t)
{
      uint8_t buf[12];
      if (tunnel[t].controlc) // Messages queued; They will carry the ack.
            return;

      *(uint16_t *) (buf + 0) = htons(0xC802); // flags/ver
      *(uint16_t *) (buf + 2) = htons(12); // length
      *(uint16_t *) (buf + 4) = htons(tunnel[t].far); // tunnel
      *(uint16_t *) (buf + 6) = htons(0); // session
      *(uint16_t *) (buf + 8) = htons(tunnel[t].ns); // sequence
      *(uint16_t *) (buf + 10) = htons(tunnel[t].nr); // sequence
      tunnelsend(buf, 12, t);
}

// add a control message to a tunnel, and send if within window
static void controladd(controlt *c, sessionidt far, tunnelidt t)
{
      *(uint16_t *) (c->buf + 2) = htons(c->length); // length
      *(uint16_t *) (c->buf + 4) = htons(tunnel[t].far); // tunnel
      *(uint16_t *) (c->buf + 6) = htons(far); // session
      *(uint16_t *) (c->buf + 8) = htons(tunnel[t].ns); // sequence
      tunnel[t].ns++;              // advance sequence
      // link in message in to queue
      if (tunnel[t].controlc)
            tunnel[t].controle->next = c;
      else
            tunnel[t].controls = c;

      tunnel[t].controle = c;
      tunnel[t].controlc++;

      // send now if space in window
      if (tunnel[t].controlc <= tunnel[t].window)
      {
            tunnel[t].try = 0;      // first send
            tunnelsend(c->buf, c->length, t);
      }
}

//
// Throttle or Unthrottle a session
//
// Throttle the data from/to through a session to no more than
// 'rate_in' kbit/sec in (from user) or 'rate_out' kbit/sec out (to
// user).
//
// If either value is -1, the current value is retained for that
// direction.
//
void throttle_session(sessionidt s, int rate_in, int rate_out)
{
      if (!session[s].opened)
            return; // No-one home.

      if (!*session[s].user)
              return; // User not logged in

      if (rate_in >= 0)
      {
            int bytes = rate_in * 1024 / 8; // kbits to bytes
            if (session[s].tbf_in)
                  free_tbf(session[s].tbf_in);

            if (rate_in > 0)
                  session[s].tbf_in = new_tbf(s, bytes * 2, bytes, send_ipin);
            else
                  session[s].tbf_in = 0;

            session[s].throttle_in = rate_in;
      }

      if (rate_out >= 0)
      {
            int bytes = rate_out * 1024 / 8;
            if (session[s].tbf_out)
                  free_tbf(session[s].tbf_out);

            if (rate_out > 0)
                  session[s].tbf_out = new_tbf(s, bytes * 2, bytes, send_ipout);
            else
                  session[s].tbf_out = 0;

            session[s].throttle_out = rate_out;
      }
}

// add/remove filters from session (-1 = no change)
void filter_session(sessionidt s, int filter_in, int filter_out)
{
      if (!session[s].opened)
            return; // No-one home.

      if (!*session[s].user)
              return; // User not logged in

      // paranoia
      if (filter_in > MAXFILTER) filter_in = -1;
      if (filter_out > MAXFILTER) filter_out = -1;
      if (session[s].filter_in > MAXFILTER) session[s].filter_in = 0;
      if (session[s].filter_out > MAXFILTER) session[s].filter_out = 0;

      if (filter_in >= 0)
      {
            if (session[s].filter_in)
                  ip_filters[session[s].filter_in - 1].used--;

            if (filter_in > 0)
                  ip_filters[filter_in - 1].used++;

            session[s].filter_in = filter_in;
      }

      if (filter_out >= 0)
      {
            if (session[s].filter_out)
                  ip_filters[session[s].filter_out - 1].used--;

            if (filter_out > 0)
                  ip_filters[filter_out - 1].used++;

            session[s].filter_out = filter_out;
      }
}

// start tidy shutdown of session
void sessionshutdown(sessionidt s, char const *reason, int cdn_result, int cdn_error, int term_cause)
{
      int walled_garden = session[s].walled_garden;


      CSTAT(sessionshutdown);

      if (!session[s].opened)
      {
            LOG(3, s, session[s].tunnel, "Called sessionshutdown on an unopened session.\n");
            return;                   // not a live session
      }

      if (!session[s].die)
      {
            struct param_kill_session data = { &tunnel[session[s].tunnel], &session[s] };
            LOG(2, s, session[s].tunnel, "Shutting down session %d: %s\n", s, reason);
            run_plugins(PLUGIN_KILL_SESSION, &data);
      }

      if (session[s].ip && !walled_garden && !session[s].die)
      {
            // RADIUS Stop message
            uint16_t r = radiusnew(s);
            if (r)
            {
                  // stop, if not already trying
                  if (radius[r].state != RADIUSSTOP)
                  {
                        radius[r].term_cause = term_cause;
                        radius[r].term_msg = reason;
                        radiussend(r, RADIUSSTOP);
                  }
            }
            else
                  LOG(1, s, session[s].tunnel, "No free RADIUS sessions for Stop message\n");

            // Save counters to dump to accounting file
            if (*config->accounting_dir && shut_acct_n < sizeof(shut_acct) / sizeof(*shut_acct))
                  memcpy(&shut_acct[shut_acct_n++], &session[s], sizeof(session[s]));
      }

      if (session[s].ip)
      {                          // IP allocated, clear and unroute
            int r;
            int routed = 0;
            for (r = 0; r < MAXROUTE && session[s].route[r].ip; r++)
            {
                  if ((session[s].ip & session[s].route[r].mask) ==
                      (session[s].route[r].ip & session[s].route[r].mask))
                        routed++;

                  routeset(s, session[s].route[r].ip, session[s].route[r].mask, 0, 0);
                  session[s].route[r].ip = 0;
            }

            if (session[s].ip_pool_index == -1) // static ip
            {
                  if (!routed) routeset(s, session[s].ip, 0, 0, 0);
                  session[s].ip = 0;
            }
            else
                  free_ip_address(s);

            // unroute IPv6, if setup
            if (session[s].ppp.ipv6cp == Opened && session[s].ipv6prefixlen)
                  route6set(s, session[s].ipv6route, session[s].ipv6prefixlen, 0);
      }

      if (session[s].throttle_in || session[s].throttle_out) // Unthrottle if throttled.
            throttle_session(s, 0, 0);

      if (cdn_result)
      {                            // Send CDN
            controlt *c = controlnew(14); // sending CDN
            if (cdn_error)
            {
                  uint8_t buf[4];
                  *(uint16_t *) buf     = htons(cdn_result);
                  *(uint16_t *) (buf+2) = htons(cdn_error);
                  controlb(c, 1, buf, 4, 1);
            }
            else
                  control16(c, 1, cdn_result, 1);

            control16(c, 14, s, 1);   // assigned session (our end)
            controladd(c, session[s].far, session[s].tunnel); // send the message
      }

      if (!session[s].die)
            session[s].die = TIME + 150; // Clean up in 15 seconds

      // update filter refcounts
      if (session[s].filter_in) ip_filters[session[s].filter_in - 1].used--;
      if (session[s].filter_out) ip_filters[session[s].filter_out - 1].used--;

      // clear PPP state
      memset(&session[s].ppp, 0, sizeof(session[s].ppp));
      sess_local[s].lcp.restart = 0;
      sess_local[s].ipcp.restart = 0;
      sess_local[s].ipv6cp.restart = 0;
      sess_local[s].ccp.restart = 0;

      cluster_send_session(s);
}

void sendipcp(sessionidt s, tunnelidt t)
{
      uint8_t buf[MAXETHER];
      uint8_t *q;

      CSTAT(sendipcp);
      LOG(3, s, t, "IPCP: send ConfigReq\n");

      if (!session[s].unique_id)
      {
            if (!++last_id) ++last_id; // skip zero
            session[s].unique_id = last_id;
      }

      q = makeppp(buf, sizeof(buf), 0, 0, s, t, PPPIPCP);
      if (!q) return;

      *q = ConfigReq;
      q[1] = session[s].unique_id & 0xf;  // ID, dont care, we only send one type of request
      *(uint16_t *) (q + 2) = htons(10);  // packet length
      q[4] = 3;                     // ip address option
      q[5] = 6;                     // option length
      *(in_addr_t *) (q + 6) = config->peer_address ? config->peer_address :
                         config->bind_address ? config->bind_address :
                         my_address; // send my IP

      tunnelsend(buf, 10 + (q - buf), t); // send it
      restart_timer(s, ipcp);
}

void sendipv6cp(sessionidt s, tunnelidt t)
{
      uint8_t buf[MAXETHER];
      uint8_t *q;

      CSTAT(sendipv6cp);
      LOG(3, s, t, "IPV6CP: send ConfigReq\n");

      q = makeppp(buf, sizeof(buf), 0, 0, s, t, PPPIPV6CP);
      if (!q) return;

      *q = ConfigReq;
      q[1] = session[s].unique_id & 0xf;  // ID, don't care, we
                                    // only send one type
                                    // of request
      *(uint16_t *) (q + 2) = htons(14);
      q[4] = 1;                     // interface identifier option
      q[5] = 10;                    // option length
      *(uint32_t *) (q + 6) = 0;          // We'll be prefix::1
      *(uint32_t *) (q + 10) = 0;
      q[13] = 1;

      tunnelsend(buf, 14 + (q - buf), t); // send it
      restart_timer(s, ipv6cp);
}

static void sessionclear(sessionidt s)
{
      memset(&session[s], 0, sizeof(session[s]));
      memset(&sess_local[s], 0, sizeof(sess_local[s]));
      memset(&cli_session_actions[s], 0, sizeof(cli_session_actions[s]));

      session[s].tunnel = T_FREE;   // Mark it as free.
      session[s].next = sessionfree;
      sessionfree = s;
}

// kill a session now
void sessionkill(sessionidt s, char *reason)
{

      CSTAT(sessionkill);

      if (!session[s].opened) // not alive
            return;

      if (session[s].next)
      {
            LOG(0, s, session[s].tunnel, "Tried to kill a session with next pointer set (%d)\n", session[s].next);
            return;
      }

      session[s].die = TIME;
      sessionshutdown(s, reason, CDN_ADMIN_DISC, TERM_ADMIN_RESET);  // close radius/routes, etc.
      if (sess_local[s].radius)
            radiusclear(sess_local[s].radius, s); // cant send clean accounting data, session is killed

      LOG(2, s, session[s].tunnel, "Kill session %d (%s): %s\n", s, session[s].user, reason);
      sessionclear(s);
      cluster_send_session(s);
}

static void tunnelclear(tunnelidt t)
{
      if (!t) return;
      memset(&tunnel[t], 0, sizeof(tunnel[t]));
      tunnel[t].state = TUNNELFREE;
}

// kill a tunnel now
static void tunnelkill(tunnelidt t, char *reason)
{
      sessionidt s;
      controlt *c;

      CSTAT(tunnelkill);

      tunnel[t].state = TUNNELDIE;

      // free control messages
      while ((c = tunnel[t].controls))
      {
            controlt * n = c->next;
            tunnel[t].controls = n;
            tunnel[t].controlc--;
            c->next = controlfree;
            controlfree = c;
      }
      // kill sessions
      for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
            if (session[s].tunnel == t)
                  sessionkill(s, reason);

      // free tunnel
      tunnelclear(t);
      LOG(1, 0, t, "Kill tunnel %d: %s\n", t, reason);
      cli_tunnel_actions[t].action = 0;
      cluster_send_tunnel(t);
}

// shut down a tunnel cleanly
static void tunnelshutdown(tunnelidt t, char *reason, int result, int error, char *msg)
{
      sessionidt s;

      CSTAT(tunnelshutdown);

      if (!tunnel[t].last || !tunnel[t].far || tunnel[t].state == TUNNELFREE)
      {
            // never set up, can immediately kill
            tunnelkill(t, reason);
            return;
      }
      LOG(1, 0, t, "Shutting down tunnel %d (%s)\n", t, reason);

      // close session
      for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
            if (session[s].tunnel == t)
                  sessionshutdown(s, reason, CDN_NONE, TERM_ADMIN_RESET);

      tunnel[t].state = TUNNELDIE;
      tunnel[t].die = TIME + 700; // Clean up in 70 seconds
      cluster_send_tunnel(t);
      // TBA - should we wait for sessions to stop?
      if (result) 
      {
            controlt *c = controlnew(4);  // sending StopCCN
            if (error)
            {
                  uint8_t buf[64];
                  int l = 4;
                  *(uint16_t *) buf     = htons(result);
                  *(uint16_t *) (buf+2) = htons(error);
                  if (msg)
                  {
                        int m = strlen(msg);
                        if (m + 4 > sizeof(buf))
                            m = sizeof(buf) - 4;

                        memcpy(buf+4, msg, m);
                        l += m;
                  }

                  controlb(c, 1, buf, l, 1);
            }
            else
                  control16(c, 1, result, 1);

            control16(c, 9, t, 1);        // assigned tunnel (our end)
            controladd(c, 0, t);          // send the message
      }
}

// read and process packet on tunnel (UDP)
void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
{
      uint8_t *chapresponse = NULL;
      uint16_t l = len, t = 0, s = 0, ns = 0, nr = 0;
      uint8_t *p = buf + 2;


      CSTAT(processudp);

      udp_rx += len;
      udp_rx_pkt++;
      LOG_HEX(5, "UDP Data", buf, len);
      STAT(tunnel_rx_packets);
      INC_STAT(tunnel_rx_bytes, len);
      if (len < 6)
      {
            LOG(1, 0, 0, "Short UDP, %d bytes\n", len);
            STAT(tunnel_rx_errors);
            return;
      }
      if ((buf[1] & 0x0F) != 2)
      {
            LOG(1, 0, 0, "Bad L2TP ver %d\n", (buf[1] & 0x0F) != 2);
            STAT(tunnel_rx_errors);
            return;
      }
      if (*buf & 0x40)
      {                          // length
            l = ntohs(*(uint16_t *) p);
            p += 2;
      }
      t = ntohs(*(uint16_t *) p);
      p += 2;
      s = ntohs(*(uint16_t *) p);
      p += 2;
      if (s >= MAXSESSION)
      {
            LOG(1, s, t, "Received UDP packet with invalid session ID\n");
            STAT(tunnel_rx_errors);
            return;
      }
      if (t >= MAXTUNNEL)
      {
            LOG(1, s, t, "Received UDP packet with invalid tunnel ID\n");
            STAT(tunnel_rx_errors);
            return;
      }
      if (*buf & 0x08)
      {                          // ns/nr
            ns = ntohs(*(uint16_t *) p);
            p += 2;
            nr = ntohs(*(uint16_t *) p);
            p += 2;
      }
      if (*buf & 0x02)
      {                          // offset
            uint16_t o = ntohs(*(uint16_t *) p);
            p += o + 2;
      }
      if ((p - buf) > l)
      {
            LOG(1, s, t, "Bad length %d>%d\n", (int) (p - buf), l);
            STAT(tunnel_rx_errors);
            return;
      }
      l -= (p - buf);

      // used to time out old tunnels
      if (t && tunnel[t].state == TUNNELOPEN)
            tunnel[t].lastrec = time_now;

      if (*buf & 0x80)
      {                          // control
            uint16_t message = 0xFFFF;    // message type
            uint8_t fatal = 0;
            uint8_t mandatory = 0;
            uint16_t asession = 0;        // assigned session
            uint32_t amagic = 0;          // magic number
            uint8_t aflags = 0;           // flags from last LCF
            uint16_t version = 0x0100;    // protocol version (we handle 0.0 as well and send that back just in case)
            char called[MAXTEL] = "";     // called number
            char calling[MAXTEL] = "";    // calling number

            if (!config->cluster_iam_master)
            {
                  master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port);
                  return;
            }

            // control messages must have bits 0x80|0x40|0x08
            // (type, length and sequence) set, and bits 0x02|0x01
            // (offset and priority) clear
            if ((*buf & 0xCB) != 0xC8)
            {
                  LOG(1, s, t, "Bad control header %02X\n", *buf);
                  STAT(tunnel_rx_errors);
                  return;
            }

            // check for duplicate tunnel open message
            if (!t && ns == 0)
            {
                  int i;

                        //
                        // Is this a duplicate of the first packet? (SCCRQ)
                        //
                  for (i = 1; i <= config->cluster_highest_tunnelid ; ++i)
                  {
                        if (tunnel[i].state != TUNNELOPENING ||
                              tunnel[i].ip != ntohl(*(in_addr_t *) & addr->sin_addr) ||
                              tunnel[i].port != ntohs(addr->sin_port) )
                              continue;
                        t = i;
                        LOG(3, s, t, "Duplicate SCCRQ?\n");
                        break;
                  }
            }

            LOG(3, s, t, "Control message (%d bytes): (unacked %d) l-ns %d l-nr %d r-ns %d r-nr %d\n",
                  l, tunnel[t].controlc, tunnel[t].ns, tunnel[t].nr, ns, nr);

            // if no tunnel specified, assign one
            if (!t)
            {
                  if (!(t = new_tunnel()))
                  {
                        LOG(1, 0, 0, "No more tunnels\n");
                        STAT(tunnel_overflow);
                        return;
                  }
                  tunnelclear(t);
                  tunnel[t].ip = ntohl(*(in_addr_t *) & addr->sin_addr);
                  tunnel[t].port = ntohs(addr->sin_port);
                  tunnel[t].window = 4; // default window
                  STAT(tunnel_created);
                  LOG(1, 0, t, "   New tunnel from %s:%u ID %d\n",
                        fmtaddr(htonl(tunnel[t].ip), 0), tunnel[t].port, t);
            }

                  // If the 'ns' just received is not the 'nr' we're
                  // expecting, just send an ack and drop it.
                  //
                  // if 'ns' is less, then we got a retransmitted packet.
                  // if 'ns' is greater than missed a packet. Either way
                  // we should ignore it.
            if (ns != tunnel[t].nr)
            {
                  // is this the sequence we were expecting?
                  STAT(tunnel_rx_errors);
                  LOG(1, 0, t, "   Out of sequence tunnel %d, (%d is not the expected %d)\n",
                        t, ns, tunnel[t].nr);

                  if (l)      // Is this not a ZLB?
                        controlnull(t);
                  return;
            }

            // check sequence of this message
            {
                  int skip = tunnel[t].window; // track how many in-window packets are still in queue
                        // some to clear maybe?
                  while (tunnel[t].controlc > 0 && (((tunnel[t].ns - tunnel[t].controlc) - nr) & 0x8000))
                  {
                        controlt *c = tunnel[t].controls;
                        tunnel[t].controls = c->next;
                        tunnel[t].controlc--;
                        c->next = controlfree;
                        controlfree = c;
                        skip--;
                        tunnel[t].try = 0; // we have progress
                  }

                  // receiver advance (do here so quoted correctly in any sends below)
                  if (l) tunnel[t].nr = (ns + 1);
                  if (skip < 0) skip = 0;
                  if (skip < tunnel[t].controlc)
                  {
                        // some control packets can now be sent that were previous stuck out of window
                        int tosend = tunnel[t].window - skip;
                        controlt *c = tunnel[t].controls;
                        while (c && skip)
                        {
                              c = c->next;
                              skip--;
                        }
                        while (c && tosend)
                        {
                              tunnel[t].try = 0; // first send
                              tunnelsend(c->buf, c->length, t);
                              c = c->next;
                              tosend--;
                        }
                  }
                  if (!tunnel[t].controlc)
                        tunnel[t].retry = 0; // caught up
            }
            if (l)
            {                     // if not a null message
                  int result = 0;
                  int error = 0;
                  char *msg = 0;

                  // Default disconnect cause/message on receipt of CDN.  Set to
                  // more specific value from attribute 1 (result code) or 46
                  // (disconnect cause) if present below.
                  int disc_cause_set = 0;
                  int disc_cause = TERM_NAS_REQUEST;
                  char const *disc_reason = "Closed (Received CDN).";

                  // process AVPs
                  while (l && !(fatal & 0x80)) // 0x80 = mandatory AVP
                  {
                        uint16_t n = (ntohs(*(uint16_t *) p) & 0x3FF);
                        uint8_t *b = p;
                        uint8_t flags = *p;
                        uint16_t mtype;

                        if (n > l)
                        {
                              LOG(1, s, t, "Invalid length in AVP\n");
                              STAT(tunnel_rx_errors);
                              return;
                        }
                        p += n;       // next
                        l -= n;
                        if (flags & 0x3C) // reserved bits, should be clear
                        {
                              LOG(1, s, t, "Unrecognised AVP flags %02X\n", *b);
                              fatal = flags;
                              result = 2; // general error
                              error = 3; // reserved field non-zero
                              msg = 0;
                              continue; // next
                        }
                        b += 2;
                        if (*(uint16_t *) (b))
                        {
                              LOG(2, s, t, "Unknown AVP vendor %d\n", ntohs(*(uint16_t *) (b)));
                              fatal = flags;
                              result = 2; // general error
                              error = 6; // generic vendor-specific error
                              msg = "unsupported vendor-specific";
                              continue; // next
                        }
                        b += 2;
                        mtype = ntohs(*(uint16_t *) (b));
                        b += 2;
                        n -= 6;

                        if (flags & 0x40)
                        {
                              uint16_t orig_len;

                              // handle hidden AVPs
                              if (!*config->l2tp_secret)
                              {
                                    LOG(1, s, t, "Hidden AVP requested, but no L2TP secret.\n");
                                    fatal = flags;
                                    result = 2; // general error
                                    error = 6; // generic vendor-specific error
                                    msg = "secret not specified";
                                    continue;
                              }
                              if (!session[s].random_vector_length)
                              {
                                    LOG(1, s, t, "Hidden AVP requested, but no random vector.\n");
                                    fatal = flags;
                                    result = 2; // general error
                                    error = 6; // generic
                                    msg = "no random vector";
                                    continue;
                              }
                              if (n < 8)
                              {
                                    LOG(2, s, t, "Short hidden AVP.\n");
                                    fatal = flags;
                                    result = 2; // general error
                                    error = 2; // length is wrong
                                    msg = 0;
                                    continue;
                              }

                              // Unhide the AVP
                              unhide_value(b, n, mtype, session[s].random_vector, session[s].random_vector_length);

                              orig_len = ntohs(*(uint16_t *) b);
                              if (orig_len > n + 2)
                              {
                                    LOG(1, s, t, "Original length %d too long in hidden AVP of length %d; wrong secret?\n",
                                        orig_len, n);

                                    fatal = flags;
                                    result = 2; // general error
                                    error = 2; // length is wrong
                                    msg = 0;
                                    continue;
                              }

                              b += 2;
                              n = orig_len;
                        }

                        LOG(4, s, t, "   AVP %d (%s) len %d%s%s\n", mtype, l2tp_avp_name(mtype), n,
                              flags & 0x40 ? ", hidden" : "", flags & 0x80 ? ", mandatory" : "");

                        switch (mtype)
                        {
                        case 0:     // message type
                              message = ntohs(*(uint16_t *) b);
                              mandatory = flags & 0x80;
                              LOG(4, s, t, "   Message type = %d (%s)\n", *b, l2tp_code(message));
                              break;
                        case 1:     // result code
                              {
                                    uint16_t rescode = ntohs(*(uint16_t *) b);
                                    char const *resdesc = "(unknown)";
                                    char const *errdesc = NULL;
                                    int cause = 0;

                                    if (message == 4)
                                    { /* StopCCN */
                                          resdesc = l2tp_stopccn_result_code(rescode);
                                          cause = TERM_LOST_SERVICE;
                                    }
                                    else if (message == 14)
                                    { /* CDN */
                                          resdesc = l2tp_cdn_result_code(rescode);
                                          if (rescode == 1)
                                                cause = TERM_LOST_CARRIER;
                                          else
                                                cause = TERM_ADMIN_RESET;
                                    }

                                    LOG(4, s, t, "   Result Code %d: %s\n", rescode, resdesc);
                                    if (n >= 4)
                                    {
                                          uint16_t errcode = ntohs(*(uint16_t *)(b + 2));
                                          errdesc = l2tp_error_code(errcode);
                                          LOG(4, s, t, "   Error Code %d: %s\n", errcode, errdesc);
                                    }
                                    if (n > 4)
                                          LOG(4, s, t, "   Error String: %.*s\n", n-4, b+4);

                                    if (cause && disc_cause_set < mtype) // take cause from attrib 46 in preference
                                    {
                                          disc_cause_set = mtype;
                                          disc_reason = errdesc ? errdesc : resdesc;
                                          disc_cause = cause;
                                    }

                                    break;
                              }
                              break;
                        case 2:     // protocol version
                              {
                                    version = ntohs(*(uint16_t *) (b));
                                    LOG(4, s, t, "   Protocol version = %d\n", version);
                                    if (version && version != 0x0100)
                                    {   // allow 0.0 and 1.0
                                          LOG(1, s, t, "   Bad protocol version %04X\n", version);
                                          fatal = flags;
                                          result = 5; // unspported protocol version
                                          error = 0x0100; // supported version
                                          msg = 0;
                                          continue; // next
                                    }
                              }
                              break;
                        case 3:     // framing capabilities
                              break;
                        case 4:     // bearer capabilities
                              break;
                        case 5:           // tie breaker
                              // We never open tunnels, so we don't care about tie breakers
                              continue;
                        case 6:     // firmware revision
                              break;
                        case 7:     // host name
                              memset(tunnel[t].hostname, 0, sizeof(tunnel[t].hostname));
                              memcpy(tunnel[t].hostname, b, (n < sizeof(tunnel[t].hostname)) ? n : sizeof(tunnel[t].hostname) - 1);
                              LOG(4, s, t, "   Tunnel hostname = \"%s\"\n", tunnel[t].hostname);
                              // TBA - to send to RADIUS
                              break;
                        case 8:     // vendor name
                              memset(tunnel[t].vendor, 0, sizeof(tunnel[t].vendor));
                              memcpy(tunnel[t].vendor, b, (n < sizeof(tunnel[t].vendor)) ? n : sizeof(tunnel[t].vendor) - 1);
                              LOG(4, s, t, "   Vendor name = \"%s\"\n", tunnel[t].vendor);
                              break;
                        case 9:     // assigned tunnel
                              tunnel[t].far = ntohs(*(uint16_t *) (b));
                              LOG(4, s, t, "   Remote tunnel id = %d\n", tunnel[t].far);
                              break;
                        case 10:    // rx window
                              tunnel[t].window = ntohs(*(uint16_t *) (b));
                              if (!tunnel[t].window)
                                    tunnel[t].window = 1; // window of 0 is silly
                              LOG(4, s, t, "   rx window = %d\n", tunnel[t].window);
                              break;
                        case 11:    // Challenge
                              {
                                    LOG(4, s, t, "   LAC requested CHAP authentication for tunnel\n");
                                    build_chap_response(b, 2, n, &chapresponse);
                              }
                              break;
                        case 13:    // Response
                              // Why did they send a response? We never challenge.
                              LOG(2, s, t, "   received unexpected challenge response\n");
                              break;

                        case 14:    // assigned session
                              asession = session[s].far = ntohs(*(uint16_t *) (b));
                              LOG(4, s, t, "   assigned session = %d\n", asession);
                              break;
                        case 15:    // call serial number
                              LOG(4, s, t, "   call serial number = %d\n", ntohl(*(uint32_t *)b));
                              break;
                        case 18:    // bearer type
                              LOG(4, s, t, "   bearer type = %d\n", ntohl(*(uint32_t *)b));
                              // TBA - for RADIUS
                              break;
                        case 19:    // framing type
                              LOG(4, s, t, "   framing type = %d\n", ntohl(*(uint32_t *)b));
                              // TBA
                              break;
                        case 21:    // called number
                              memset(called, 0, sizeof(called));
                              memcpy(called, b, (n < sizeof(called)) ? n : sizeof(called) - 1);
                              LOG(4, s, t, "   Called <%s>\n", called);
                              break;
                        case 22:    // calling number
                              memset(calling, 0, sizeof(calling));
                              memcpy(calling, b, (n < sizeof(calling)) ? n : sizeof(calling) - 1);
                              LOG(4, s, t, "   Calling <%s>\n", calling);
                              break;
                        case 23:    // subtype
                              break;
                        case 24:    // tx connect speed
                              if (n == 4)
                              {
                                    session[s].tx_connect_speed = ntohl(*(uint32_t *)b);
                              }
                              else
                              {
                                    // AS5300s send connect speed as a string
                                    char tmp[30];
                                    memset(tmp, 0, sizeof(tmp));
                                    memcpy(tmp, b, (n < sizeof(tmp)) ? n : sizeof(tmp) - 1);
                                    session[s].tx_connect_speed = atol(tmp);
                              }
                              LOG(4, s, t, "   TX connect speed <%u>\n", session[s].tx_connect_speed);
                              break;
                        case 38:    // rx connect speed
                              if (n == 4)
                              {
                                    session[s].rx_connect_speed = ntohl(*(uint32_t *)b);
                              }
                              else
                              {
                                    // AS5300s send connect speed as a string
                                    char tmp[30];
                                    memset(tmp, 0, sizeof(tmp));
                                    memcpy(tmp, b, (n < sizeof(tmp)) ? n : sizeof(tmp) - 1);
                                    session[s].rx_connect_speed = atol(tmp);
                              }
                              LOG(4, s, t, "   RX connect speed <%u>\n", session[s].rx_connect_speed);
                              break;
                        case 25:    // Physical Channel ID
                              {
                                    uint32_t tmp = ntohl(*(uint32_t *) b);
                                    LOG(4, s, t, "   Physical Channel ID <%X>\n", tmp);
                                    break;
                              }
                        case 29:    // Proxy Authentication Type
                              {
                                    uint16_t atype = ntohs(*(uint16_t *)b);
                                    LOG(4, s, t, "   Proxy Auth Type %d (%s)\n", atype, ppp_auth_type(atype));
                                    break;
                              }
                        case 30:    // Proxy Authentication Name
                              {
                                    char authname[64];
                                    memset(authname, 0, sizeof(authname));
                                    memcpy(authname, b, (n < sizeof(authname)) ? n : sizeof(authname) - 1);
                                    LOG(4, s, t, "   Proxy Auth Name (%s)\n",
                                          authname);
                                    break;
                              }
                        case 31:    // Proxy Authentication Challenge
                              {
                                    LOG(4, s, t, "   Proxy Auth Challenge\n");
                                    break;
                              }
                        case 32:    // Proxy Authentication ID
                              {
                                    uint16_t authid = ntohs(*(uint16_t *)(b));
                                    LOG(4, s, t, "   Proxy Auth ID (%d)\n", authid);
                                    break;
                              }
                        case 33:    // Proxy Authentication Response
                              LOG(4, s, t, "   Proxy Auth Response\n");
                              break;
                        case 27:    // last sent lcp
                              {        // find magic number
                                    uint8_t *p = b, *e = p + n;
                                    while (p + 1 < e && p[1] && p + p[1] <= e)
                                    {
                                          if (*p == 5 && p[1] == 6) // Magic-Number
                                                amagic = ntohl(*(uint32_t *) (p + 2));
                                          else if (*p == 7) // Protocol-Field-Compression
                                                aflags |= SESSION_PFC;
                                          else if (*p == 8) // Address-and-Control-Field-Compression
                                                aflags |= SESSION_ACFC;
                                          p += p[1];
                                    }
                              }
                              break;
                        case 28:    // last recv lcp confreq
                              break;
                        case 26:    // Initial Received LCP CONFREQ
                              break;
                        case 39:    // seq required - we control it as an LNS anyway...
                              break;
                        case 36:    // Random Vector
                              LOG(4, s, t, "   Random Vector received.  Enabled AVP Hiding.\n");
                              memset(session[s].random_vector, 0, sizeof(session[s].random_vector));
                              if (n > sizeof(session[s].random_vector))
                                    n = sizeof(session[s].random_vector);
                              memcpy(session[s].random_vector, b, n);
                              session[s].random_vector_length = n;
                              break;
                        case 46:    // ppp disconnect cause
                              if (n >= 5)
                              {
                                    uint16_t code = ntohs(*(uint16_t *) b);
                                    uint16_t proto = ntohs(*(uint16_t *) (b + 2));
                                    uint8_t dir = *(b + 4);

                                    LOG(4, s, t, "   PPP disconnect cause "
                                          "(code=%u, proto=%04X, dir=%u, msg=\"%.*s\")\n",
                                          code, proto, dir, n - 5, b + 5);

                                    disc_cause_set = mtype;

                                    switch (code)
                                    {
                                    case 1: // admin disconnect
                                          disc_cause = TERM_ADMIN_RESET;
                                          disc_reason = "Administrative disconnect";
                                          break;
                                    case 3: // lcp terminate
                                          if (dir != 2) break; // 1=peer (LNS), 2=local (LAC)
                                          disc_cause = TERM_USER_REQUEST;
                                          disc_reason = "Normal disconnection";
                                          break;
                                    case 4: // compulsory encryption unavailable
                                          if (dir != 1) break; // 1=refused by peer, 2=local
                                          disc_cause = TERM_USER_ERROR;
                                          disc_reason = "Compulsory encryption refused";
                                          break;
                                    case 5: // lcp: fsm timeout
                                          disc_cause = TERM_PORT_ERROR;
                                          disc_reason = "LCP: FSM timeout";
                                          break;
                                    case 6: // lcp: no recognisable lcp packets received
                                          disc_cause = TERM_PORT_ERROR;
                                          disc_reason = "LCP: no recognisable LCP packets";
                                          break;
                                    case 7: // lcp: magic-no error (possibly looped back)
                                          disc_cause = TERM_PORT_ERROR;
                                          disc_reason = "LCP: magic-no error (possible loop)";
                                          break;
                                    case 8: // lcp: echo request timeout
                                          disc_cause = TERM_PORT_ERROR;
                                          disc_reason = "LCP: echo request timeout";
                                          break;
                                    case 13: // auth: fsm timeout
                                          disc_cause = TERM_SERVICE_UNAVAILABLE;
                                          disc_reason = "Authentication: FSM timeout";
                                          break;
                                    case 15: // auth: unacceptable auth protocol
                                          disc_cause = TERM_SERVICE_UNAVAILABLE;
                                          disc_reason = "Unacceptable authentication protocol";
                                          break;
                                    case 16: // auth: authentication failed
                                          disc_cause = TERM_SERVICE_UNAVAILABLE;
                                          disc_reason = "Authentication failed";
                                          break;
                                    case 17: // ncp: fsm timeout
                                          disc_cause = TERM_SERVICE_UNAVAILABLE;
                                          disc_reason = "NCP: FSM timeout";
                                          break;
                                    case 18: // ncp: no ncps available
                                          disc_cause = TERM_SERVICE_UNAVAILABLE;
                                          disc_reason = "NCP: no NCPs available";
                                          break;
                                    case 19: // ncp: failure to converge on acceptable address
                                          disc_cause = TERM_SERVICE_UNAVAILABLE;
                                          disc_reason = (dir == 1)
                                                ? "NCP: too many Configure-Naks received from peer"
                                                : "NCP: too many Configure-Naks sent to peer";
                                          break;
                                    case 20: // ncp: user not permitted to use any address
                                          disc_cause = TERM_SERVICE_UNAVAILABLE;
                                          disc_reason = (dir == 1)
                                                ? "NCP: local link address not acceptable to peer"
                                                : "NCP: remote link address not acceptable";
                                          break;
                                    }
                              }
                              break;
                        default:
                              {
                                    static char e[] = "unknown AVP 0xXXXX";
                                    LOG(2, s, t, "   Unknown AVP type %d\n", mtype);
                                    fatal = flags;
                                    result = 2; // general error
                                    error = 8; // unknown mandatory AVP
                                    sprintf((msg = e) + 14, "%04x", mtype);
                                    continue; // next
                              }
                        }
                  }
                  // process message
                  if (fatal & 0x80)
                        tunnelshutdown(t, "Invalid mandatory AVP", result, error, msg);
                  else
                        switch (message)
                        {
                        case 1:       // SCCRQ - Start Control Connection Request
                              tunnel[t].state = TUNNELOPENING;
                              if (main_quit != QUIT_SHUTDOWN)
                              {
                                    controlt *c = controlnew(2); // sending SCCRP
                                    control16(c, 2, version, 1); // protocol version
                                    control32(c, 3, 3, 1); // framing
                                    controls(c, 7, hostname, 1); // host name
                                    if (chapresponse) controlb(c, 13, chapresponse, 16, 1); // Challenge response
                                    control16(c, 9, t, 1); // assigned tunnel
                                    controladd(c, 0, t); // send the resply
                              }
                              else
                              {
                                    tunnelshutdown(t, "Shutting down", 6, 0, 0);
                              }
                              break;
                        case 2:       // SCCRP
                              tunnel[t].state = TUNNELOPEN;
                              break;
                        case 3:       // SCCN
                              tunnel[t].state = TUNNELOPEN;
                              controlnull(t); // ack
                              break;
                        case 4:       // StopCCN
                              controlnull(t); // ack
                              tunnelshutdown(t, "Stopped", 0, 0, 0); // Shut down cleanly
                              break;
                        case 6:       // HELLO
                              controlnull(t); // simply ACK
                              break;
                        case 7:       // OCRQ
                              // TBA
                              break;
                        case 8:       // OCRO
                              // TBA
                              break;
                        case 9:       // OCCN
                              // TBA
                              break;
                        case 10:      // ICRQ
                              if (sessionfree && main_quit != QUIT_SHUTDOWN)
                              {
                                    controlt *c = controlnew(11); // ICRP

                                    s = sessionfree;
                                    sessionfree = session[s].next;
                                    memset(&session[s], 0, sizeof(session[s]));

                                    if (s > config->cluster_highest_sessionid)
                                          config->cluster_highest_sessionid = s;

                                    session[s].opened = time_now;
                                    session[s].tunnel = t;
                                    session[s].far = asession;
                                    session[s].last_packet = time_now;
                                    LOG(3, s, t, "New session (%d/%d)\n", tunnel[t].far, session[s].far);
                                    control16(c, 14, s, 1); // assigned session
                                    controladd(c, asession, t); // send the reply

                                    strncpy(session[s].called, called, sizeof(session[s].called) - 1);
                                    strncpy(session[s].calling, calling, sizeof(session[s].calling) - 1);

                                    session[s].ppp.phase = Establish;
                                    session[s].ppp.lcp = Starting;

                                    STAT(session_created);
                                    break;
                              }

                              {
                                    controlt *c = controlnew(14); // CDN
                                    if (!sessionfree)
                                    {
                                          STAT(session_overflow);
                                          LOG(1, 0, t, "No free sessions\n");
                                          control16(c, 1, 4, 0); // temporary lack of resources
                                    }
                                    else
                                          control16(c, 1, 2, 7); // shutting down, try another

                                    controladd(c, asession, t); // send the message
                              }
                              return;
                        case 11:      // ICRP
                              // TBA
                              break;
                        case 12:      // ICCN
                              if (amagic == 0) amagic = time_now;
                              session[s].magic = amagic; // set magic number
                              session[s].flags = aflags; // set flags received
                              session[s].mru = PPPoE_MRU; // default
                              controlnull(t); // ack

                              // start LCP
                              sess_local[s].lcp_authtype = config->radius_authprefer;
                              sess_local[s].ppp_mru = MRU;
                              sendlcp(s, t);
                              change_state(s, lcp, RequestSent);
                              break;

                        case 14:      // CDN
                              controlnull(t); // ack
                              sessionshutdown(s, disc_reason, CDN_NONE, disc_cause);
                              break;
                        case 0xFFFF:
                              LOG(1, s, t, "Missing message type\n");
                              break;
                        default:
                              STAT(tunnel_rx_errors);
                              if (mandatory)
                                    tunnelshutdown(t, "Unknown message type", 2, 6, "unknown message type");
                              else
                                    LOG(1, s, t, "Unknown message type %d\n", message);
                              break;
                        }
                  if (chapresponse) free(chapresponse);
                  cluster_send_tunnel(t);
            }
            else
            {
                  LOG(4, s, t, "   Got a ZLB ack\n");
            }
      }
      else
      {                          // data
            uint16_t proto;

            LOG_HEX(5, "Receive Tunnel Data", p, l);
            if (l > 2 && p[0] == 0xFF && p[1] == 0x03)
            {                     // HDLC address header, discard
                  p += 2;
                  l -= 2;
            }
            if (l < 2)
            {
                  LOG(1, s, t, "Short ppp length %d\n", l);
                  STAT(tunnel_rx_errors);
                  return;
            }
            if (*p & 1)
            {
                  proto = *p++;
                  l--;
            }
            else
            {
                  proto = ntohs(*(uint16_t *) p);
                  p += 2;
                  l -= 2;
            }

            if (s && !session[s].opened)  // Is something wrong??
            {
                  if (!config->cluster_iam_master)
                  {
                        // Pass it off to the master to deal with..
                        master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port);
                        return;
                  }


                  LOG(1, s, t, "UDP packet contains session which is not opened.  Dropping packet.\n");
                  STAT(tunnel_rx_errors);
                  return;
            }

            if (proto == PPPPAP)
            {
                  session[s].last_packet = time_now;
                  if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
                  processpap(s, t, p, l);
            }
            else if (proto == PPPCHAP)
            {
                  session[s].last_packet = time_now;
                  if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
                  processchap(s, t, p, l);
            }
            else if (proto == PPPLCP)
            {
                  session[s].last_packet = time_now;
                  if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
                  processlcp(s, t, p, l);
            }
            else if (proto == PPPIPCP)
            {
                  session[s].last_packet = time_now;
                  if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
                  processipcp(s, t, p, l);
            }
            else if (proto == PPPIPV6CP && config->ipv6_prefix.s6_addr[0])
            {
                  session[s].last_packet = time_now;
                  if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
                  processipv6cp(s, t, p, l);
            }
            else if (proto == PPPCCP)
            {
                  session[s].last_packet = time_now;
                  if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
                  processccp(s, t, p, l);
            }
            else if (proto == PPPIP)
            {
                  if (session[s].die)
                  {
                        LOG(4, s, t, "Session %d is closing.  Don't process PPP packets\n", s);
                        return;              // closing session, PPP not processed
                  }

                  session[s].last_packet = time_now;
                  if (session[s].walled_garden && !config->cluster_iam_master)
                  {
                        master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port);
                        return;
                  }

                  processipin(s, t, p, l);
            }
            else if (proto == PPPIPV6 && config->ipv6_prefix.s6_addr[0])
            {
                  if (session[s].die)
                  {
                        LOG(4, s, t, "Session %d is closing.  Don't process PPP packets\n", s);
                        return;              // closing session, PPP not processed
                  }

                  session[s].last_packet = time_now;
                  if (session[s].walled_garden && !config->cluster_iam_master)
                  {
                        master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port);
                        return;
                  }

                  processipv6in(s, t, p, l);
            }
            else if (session[s].ppp.lcp == Opened)
            {
                  session[s].last_packet = time_now;
                  if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
                  protoreject(s, t, p, l, proto);
            }
            else
            {
                  LOG(2, s, t, "Unknown PPP protocol 0x%04X received in LCP %s state\n",
                        proto, ppp_state(session[s].ppp.lcp));
            }
      }
}

// read and process packet on tun
static void processtun(uint8_t * buf, int len)
{
      LOG_HEX(5, "Receive TUN Data", buf, len);
      STAT(tun_rx_packets);
      INC_STAT(tun_rx_bytes, len);

      CSTAT(processtun);

      eth_rx_pkt++;
      eth_rx += len;
      if (len < 22)
      {
            LOG(1, 0, 0, "Short tun packet %d bytes\n", len);
            STAT(tun_rx_errors);
            return;
      }

      if (*(uint16_t *) (buf + 2) == htons(PKTIP)) // IPv4
            processipout(buf, len);
      else if (*(uint16_t *) (buf + 2) == htons(PKTIPV6) // IPV6
          && config->ipv6_prefix.s6_addr[0])
            processipv6out(buf, len);

      // Else discard.
}

// Handle retries, timeouts.  Runs every 1/10th sec, want to ensure
// that we look at the whole of the tunnel, radius and session tables
// every second
static void regular_cleanups(double period)
{
      // Next tunnel, radius and session to check for actions on.
      static tunnelidt t = 0;
      static int r = 0;
      static sessionidt s = 0;

      int t_actions = 0;
      int r_actions = 0;
      int s_actions = 0;

      int t_slice;
      int r_slice;
      int s_slice;

      int i;
      int a;

      // divide up tables into slices based on the last run
      t_slice = config->cluster_highest_tunnelid  * period;
      r_slice = (MAXRADIUS - 1)                   * period;
      s_slice = config->cluster_highest_sessionid * period;

      if (t_slice < 1)
          t_slice = 1;
      else if (t_slice > config->cluster_highest_tunnelid)
          t_slice = config->cluster_highest_tunnelid;

      if (r_slice < 1)
          r_slice = 1;
      else if (r_slice > (MAXRADIUS - 1))
          r_slice = MAXRADIUS - 1;

      if (s_slice < 1)
          s_slice = 1;
      else if (s_slice > config->cluster_highest_sessionid)
          s_slice = config->cluster_highest_sessionid;

      LOG(4, 0, 0, "Begin regular cleanup (last %f seconds ago)\n", period);

      for (i = 0; i < t_slice; i++)
      {
            t++;
            if (t > config->cluster_highest_tunnelid)
                  t = 1;

            // check for expired tunnels
            if (tunnel[t].die && tunnel[t].die <= TIME)
            {
                  STAT(tunnel_timeout);
                  tunnelkill(t, "Expired");
                  t_actions++;
                  continue;
            }
            // check for message resend
            if (tunnel[t].retry && tunnel[t].controlc)
            {
                  // resend pending messages as timeout on reply
                  if (tunnel[t].retry <= TIME)
                  {
                        controlt *c = tunnel[t].controls;
                        uint8_t w = tunnel[t].window;
                        tunnel[t].try++; // another try
                        if (tunnel[t].try > 5)
                              tunnelkill(t, "Timeout on control message"); // game over
                        else
                              while (c && w--)
                              {
                                    tunnelsend(c->buf, c->length, t);
                                    c = c->next;
                              }

                        t_actions++;
                  }
            }
            // Send hello
            if (tunnel[t].state == TUNNELOPEN && !tunnel[t].controlc && (time_now - tunnel[t].lastrec) > 60)
            {
                  controlt *c = controlnew(6); // sending HELLO
                  controladd(c, 0, t); // send the message
                  LOG(3, 0, t, "Sending HELLO message\n");
                  t_actions++;
            }

            // Check for tunnel changes requested from the CLI
            if ((a = cli_tunnel_actions[t].action))
            {
                  cli_tunnel_actions[t].action = 0;
                  if (a & CLI_TUN_KILL)
                  {
                        LOG(2, 0, t, "Dropping tunnel by CLI\n");
                        tunnelshutdown(t, "Requested by administrator", 1, 0, 0);
                        t_actions++;
                  }
            }
      }

      for (i = 0; i < r_slice; i++)
      {
            r++;
            if (r >= MAXRADIUS)
                  r = 1;

            if (!radius[r].state)
                  continue;

            if (radius[r].retry <= TIME)
            {
                  radiusretry(r);
                  r_actions++;
            }
      }

      for (i = 0; i < s_slice; i++)
      {
            s++;
            if (s > config->cluster_highest_sessionid)
                  s = 1;

            if (!session[s].opened) // Session isn't in use
                  continue;

            // check for expired sessions
            if (session[s].die)
            {
                  if (session[s].die <= TIME)
                  {
                        sessionkill(s, "Expired");
                        s_actions++;
                  }
                  continue;
            }

            // PPP timeouts
            if (sess_local[s].lcp.restart <= time_now)
            {
                  int next_state = session[s].ppp.lcp;
                  switch (session[s].ppp.lcp)
                  {
                  case RequestSent:
                  case AckReceived:
                        next_state = RequestSent;

                  case AckSent:
                        if (sess_local[s].lcp.conf_sent < config->ppp_max_configure)
                        {
                              LOG(3, s, session[s].tunnel, "No ACK for LCP ConfigReq... resending\n");
                              sendlcp(s, session[s].tunnel);
                              change_state(s, lcp, next_state);
                        }
                        else
                        {
                              sessionshutdown(s, "No response to LCP ConfigReq.", CDN_ADMIN_DISC, TERM_LOST_SERVICE);
                              STAT(session_timeout);
                        }

                        s_actions++;
                  }

                  if (session[s].die)
                        continue;
            }

            if (sess_local[s].ipcp.restart <= time_now)
            {
                  int next_state = session[s].ppp.ipcp;
                  switch (session[s].ppp.ipcp)
                  {
                  case RequestSent:
                  case AckReceived:
                        next_state = RequestSent;

                  case AckSent:
                        if (sess_local[s].ipcp.conf_sent < config->ppp_max_configure)
                        {
                              LOG(3, s, session[s].tunnel, "No ACK for IPCP ConfigReq... resending\n");
                              sendipcp(s, session[s].tunnel);
                              change_state(s, ipcp, next_state);
                        }
                        else
                        {
                              sessionshutdown(s, "No response to IPCP ConfigReq.", CDN_ADMIN_DISC, TERM_LOST_SERVICE);
                              STAT(session_timeout);
                        }

                        s_actions++;
                  }

                  if (session[s].die)
                        continue;
            }

            if (sess_local[s].ipv6cp.restart <= time_now)
            {
                  int next_state = session[s].ppp.ipv6cp;
                  switch (session[s].ppp.ipv6cp)
                  {
                  case RequestSent:
                  case AckReceived:
                        next_state = RequestSent;

                  case AckSent:
                        if (sess_local[s].ipv6cp.conf_sent < config->ppp_max_configure)
                        {
                              LOG(3, s, session[s].tunnel, "No ACK for IPV6CP ConfigReq... resending\n");
                              sendipv6cp(s, session[s].tunnel);
                              change_state(s, ipv6cp, next_state);
                        }
                        else
                        {
                              LOG(3, s, session[s].tunnel, "No ACK for IPV6CP ConfigReq\n");
                              change_state(s, ipv6cp, Stopped);
                        }

                        s_actions++;
                  }
            }

            if (sess_local[s].ccp.restart <= time_now)
            {
                  int next_state = session[s].ppp.ccp;
                  switch (session[s].ppp.ccp)
                  {
                  case RequestSent:
                  case AckReceived:
                        next_state = RequestSent;

                  case AckSent:
                        if (sess_local[s].ccp.conf_sent < config->ppp_max_configure)
                        {
                              LOG(3, s, session[s].tunnel, "No ACK for CCP ConfigReq... resending\n");
                              sendccp(s, session[s].tunnel);
                              change_state(s, ccp, next_state);
                        }
                        else
                        {
                              LOG(3, s, session[s].tunnel, "No ACK for CCP ConfigReq\n");
                              change_state(s, ccp, Stopped);
                        }

                        s_actions++;
                  }
            }

            // Drop sessions who have not responded within IDLE_TIMEOUT seconds
            if (session[s].last_packet && (time_now - session[s].last_packet >= IDLE_TIMEOUT))
            {
                  sessionshutdown(s, "No response to LCP ECHO requests.", CDN_ADMIN_DISC, TERM_LOST_SERVICE);
                  STAT(session_timeout);
                  s_actions++;
                  continue;
            }

            // No data in ECHO_TIMEOUT seconds, send LCP ECHO
            if (session[s].ppp.phase >= Establish && (time_now - session[s].last_packet >= ECHO_TIMEOUT) &&
                  (time_now - sess_local[s].last_echo >= ECHO_TIMEOUT))
            {
                  uint8_t b[MAXETHER];

                  uint8_t *q = makeppp(b, sizeof(b), 0, 0, s, session[s].tunnel, PPPLCP);
                  if (!q) continue;

                  *q = EchoReq;
                  *(uint8_t *)(q + 1) = (time_now % 255); // ID
                  *(uint16_t *)(q + 2) = htons(8); // Length
                  *(uint32_t *)(q + 4) = session[s].ppp.lcp == Opened ? htonl(session[s].magic) : 0; // Magic Number

                  LOG(4, s, session[s].tunnel, "No data in %d seconds, sending LCP ECHO\n",
                              (int)(time_now - session[s].last_packet));
                  tunnelsend(b, 24, session[s].tunnel); // send it
                  sess_local[s].last_echo = time_now;
                  s_actions++;
            }

            // Check for actions requested from the CLI
            if ((a = cli_session_actions[s].action))
            {
                  int send = 0;

                  cli_session_actions[s].action = 0;
                  if (a & CLI_SESS_KILL)
                  {
                        LOG(2, s, session[s].tunnel, "Dropping session by CLI\n");
                        sessionshutdown(s, "Requested by administrator.", CDN_ADMIN_DISC, TERM_ADMIN_RESET);
                        a = 0; // dead, no need to check for other actions
                        s_actions++;
                  }

                  if (a & CLI_SESS_NOSNOOP)
                  {
                        LOG(2, s, session[s].tunnel, "Unsnooping session by CLI\n");
                        session[s].snoop_ip = 0;
                        session[s].snoop_port = 0;
                        s_actions++;
                        send++;
                  }
                  else if (a & CLI_SESS_SNOOP)
                  {
                        LOG(2, s, session[s].tunnel, "Snooping session by CLI (to %s:%d)\n",
                            fmtaddr(cli_session_actions[s].snoop_ip, 0),
                            cli_session_actions[s].snoop_port);

                        session[s].snoop_ip = cli_session_actions[s].snoop_ip;
                        session[s].snoop_port = cli_session_actions[s].snoop_port;
                        s_actions++;
                        send++;
                  }

                  if (a & CLI_SESS_NOTHROTTLE)
                  {
                        LOG(2, s, session[s].tunnel, "Un-throttling session by CLI\n");
                        throttle_session(s, 0, 0);
                        s_actions++;
                        send++;
                  }
                  else if (a & CLI_SESS_THROTTLE)
                  {
                        LOG(2, s, session[s].tunnel, "Throttling session by CLI (to %dkb/s up and %dkb/s down)\n",
                            cli_session_actions[s].throttle_in,
                            cli_session_actions[s].throttle_out);

                        throttle_session(s, cli_session_actions[s].throttle_in, cli_session_actions[s].throttle_out);
                        s_actions++;
                        send++;
                  }

                  if (a & CLI_SESS_NOFILTER)
                  {
                        LOG(2, s, session[s].tunnel, "Un-filtering session by CLI\n");
                        filter_session(s, 0, 0);
                        s_actions++;
                        send++;
                  }
                  else if (a & CLI_SESS_FILTER)
                  {
                        LOG(2, s, session[s].tunnel, "Filtering session by CLI (in=%d, out=%d)\n",
                            cli_session_actions[s].filter_in,
                            cli_session_actions[s].filter_out);

                        filter_session(s, cli_session_actions[s].filter_in, cli_session_actions[s].filter_out);
                        s_actions++;
                        send++;
                  }

                  if (send)
                        cluster_send_session(s);
            }

            // RADIUS interim accounting
            if (config->radius_accounting && config->radius_interim > 0
                && session[s].ip && !session[s].walled_garden
                && !sess_local[s].radius // RADIUS already in progress
                && time_now - sess_local[s].last_interim >= config->radius_interim)
            {
                  int rad = radiusnew(s);
                  if (!rad)
                  {
                        LOG(1, s, session[s].tunnel, "No free RADIUS sessions for Interim message\n");
                        STAT(radius_overflow);
                        continue;
                  }

                  LOG(3, s, session[s].tunnel, "Sending RADIUS Interim for %s (%u)\n",
                        session[s].user, session[s].unique_id);

                  radiussend(rad, RADIUSINTERIM);
                  sess_local[s].last_interim = time_now;
                  s_actions++;
            }
      }

      LOG(4, 0, 0, "End regular cleanup: checked %d/%d/%d tunnels/radius/sessions; %d/%d/%d actions\n",
            t_slice, r_slice, s_slice, t_actions, r_actions, s_actions);
}

//
// Are we in the middle of a tunnel update, or radius
// requests??
//
static int still_busy(void)
{
      int i;
      static clockt last_talked = 0;
      static clockt start_busy_wait = 0;

      if (!config->cluster_iam_master)
      {
#ifdef BGP
            static time_t stopped_bgp = 0;
            if (bgp_configured)
            {
                  if (!stopped_bgp)
                  {
                        LOG(1, 0, 0, "Shutting down in %d seconds, stopping BGP...\n", QUIT_DELAY);

                        for (i = 0; i < BGP_NUM_PEERS; i++)
                              if (bgp_peers[i].state == Established)
                                    bgp_stop(&bgp_peers[i]);

                        stopped_bgp = time_now;

                        // we don't want to become master
                        cluster_send_ping(0);

                        return 1;
                  }

                  if (time_now < (stopped_bgp + QUIT_DELAY))
                        return 1;
            }
#endif /* BGP */

            return 0;
      }

      if (main_quit == QUIT_SHUTDOWN)
      {
            static int dropped = 0;
            if (!dropped)
            {
                  int i;

                  LOG(1, 0, 0, "Dropping sessions and tunnels\n");
                  for (i = 1; i < MAXTUNNEL; i++)
                        if (tunnel[i].ip || tunnel[i].state)
                              tunnelshutdown(i, "L2TPNS Closing", 6, 0, 0);

                  dropped = 1;
            }
      }

      if (start_busy_wait == 0)
            start_busy_wait = TIME;

      for (i = config->cluster_highest_tunnelid ; i > 0 ; --i)
      {
            if (!tunnel[i].controlc)
                  continue;

            if (last_talked != TIME)
            {
                  LOG(2, 0, 0, "Tunnel %d still has un-acked control messages.\n", i);
                  last_talked = TIME;
            }
            return 1;
      }

      // We stop waiting for radius after BUSY_WAIT_TIME 1/10th seconds
      if (abs(TIME - start_busy_wait) > BUSY_WAIT_TIME)
      {
            LOG(1, 0, 0, "Giving up waiting for RADIUS to be empty.  Shutting down anyway.\n");
            return 0;
      }

      for (i = 1; i < MAXRADIUS; i++)
      {
            if (radius[i].state == RADIUSNULL)
                  continue;
              if (radius[i].state == RADIUSWAIT)
                  continue;

            if (last_talked != TIME)
            {
                  LOG(2, 0, 0, "Radius session %d is still busy (sid %d)\n", i, radius[i].session);
                  last_talked = TIME;
            }
            return 1;
      }

      return 0;
}

#ifdef HAVE_EPOLL
# include <sys/epoll.h>
#else
# define FAKE_EPOLL_IMPLEMENTATION /* include the functions */
# include "fake_epoll.h"
#endif

// the base set of fds polled: cli, cluster, tun, udp, control, dae
#define BASE_FDS  6

// additional polled fds
#ifdef BGP
# define EXTRA_FDS      BGP_NUM_PEERS
#else
# define EXTRA_FDS      0
#endif

// main loop - gets packets on tun or udp and processes them
static void mainloop(void)
{
      int i;
      uint8_t buf[65536];
      clockt next_cluster_ping = 0; // send initial ping immediately
      struct epoll_event events[BASE_FDS + RADIUS_FDS + EXTRA_FDS];
      int maxevent = sizeof(events)/sizeof(*events);

      if ((epollfd = epoll_create(maxevent)) < 0)
      {
            LOG(0, 0, 0, "epoll_create failed: %s\n", strerror(errno));
            exit(1);
      }

      LOG(4, 0, 0, "Beginning of main loop.  clifd=%d, cluster_sockfd=%d, tunfd=%d, udpfd=%d, controlfd=%d, daefd=%d\n",
            clifd, cluster_sockfd, tunfd, udpfd, controlfd, daefd);

      /* setup our fds to poll for input */
      {
            static struct event_data d[BASE_FDS];
            struct epoll_event e;

            e.events = EPOLLIN;
            i = 0;

            d[i].type = FD_TYPE_CLI;
            e.data.ptr = &d[i++];
            epoll_ctl(epollfd, EPOLL_CTL_ADD, clifd, &e);

            d[i].type = FD_TYPE_CLUSTER;
            e.data.ptr = &d[i++];
            epoll_ctl(epollfd, EPOLL_CTL_ADD, cluster_sockfd, &e);

            d[i].type = FD_TYPE_TUN;
            e.data.ptr = &d[i++];
            epoll_ctl(epollfd, EPOLL_CTL_ADD, tunfd, &e);

            d[i].type = FD_TYPE_UDP;
            e.data.ptr = &d[i++];
            epoll_ctl(epollfd, EPOLL_CTL_ADD, udpfd, &e);

            d[i].type = FD_TYPE_CONTROL;
            e.data.ptr = &d[i++];
            epoll_ctl(epollfd, EPOLL_CTL_ADD, controlfd, &e);

            d[i].type = FD_TYPE_DAE;
            e.data.ptr = &d[i++];
            epoll_ctl(epollfd, EPOLL_CTL_ADD, daefd, &e);
      }

#ifdef BGP
      signal(SIGPIPE, SIG_IGN);
      bgp_setup(config->as_number);
      if (config->bind_address)
            bgp_add_route(config->bind_address, 0xffffffff);

      for (i = 0; i < BGP_NUM_PEERS; i++)
      {
            if (config->neighbour[i].name[0])
                  bgp_start(&bgp_peers[i], config->neighbour[i].name,
                        config->neighbour[i].as, config->neighbour[i].keepalive,
                        config->neighbour[i].hold, 0); /* 0 = routing disabled */
      }
#endif /* BGP */

      while (!main_quit || still_busy())
      {
            int more = 0;
            int n;


            if (main_reload)
            {
                  main_reload = 0;
                  read_config_file();
                  config->reload_config++;
            }

            if (config->reload_config)
            {
                  config->reload_config = 0;
                  update_config();
            }

#ifdef BGP
            bgp_set_poll();
#endif /* BGP */

            n = epoll_wait(epollfd, events, maxevent, 100); // timeout 100ms (1/10th sec)
            STAT(select_called);

            TIME = now(NULL);
            if (n < 0)
            {
                  if (errno == EINTR ||
                      errno == ECHILD) // EINTR was clobbered by sigchild_handler()
                        continue;

                  LOG(0, 0, 0, "Error returned from select(): %s\n", strerror(errno));
                  break; // exit
            }

            if (n)
            {
                  struct sockaddr_in addr;
                  struct in_addr local;
                  socklen_t alen;
                  int c, s;
                  int udp_ready = 0;
                  int tun_ready = 0;
                  int cluster_ready = 0;
                  int udp_pkts = 0;
                  int tun_pkts = 0;
                  int cluster_pkts = 0;
#ifdef BGP
                  uint32_t bgp_events[BGP_NUM_PEERS];
                  memset(bgp_events, 0, sizeof(bgp_events));
#endif /* BGP */

                  for (c = n, i = 0; i < c; i++)
                  {
                        struct event_data *d = events[i].data.ptr;

                        switch (d->type)
                        {
                        case FD_TYPE_CLI: // CLI connections
                        {
                              int cli;
                              
                              alen = sizeof(addr);
                              if ((cli = accept(clifd, (struct sockaddr *)&addr, &alen)) >= 0)
                              {
                                    cli_do(cli);
                                    close(cli);
                              }
                              else
                                    LOG(0, 0, 0, "accept error: %s\n", strerror(errno));

                              n--;
                              break;
                        }

                        // these are handled below, with multiple interleaved reads
                        case FD_TYPE_CLUSTER:   cluster_ready++; break;
                        case FD_TYPE_TUN: tun_ready++; break;
                        case FD_TYPE_UDP: udp_ready++; break;

                        case FD_TYPE_CONTROL: // nsctl commands
                              alen = sizeof(addr);
                              s = recvfromto(controlfd, buf, sizeof(buf), MSG_WAITALL, (struct sockaddr *) &addr, &alen, &local);
                              if (s > 0) processcontrol(buf, s, &addr, alen, &local);
                              n--;
                              break;

                        case FD_TYPE_DAE: // DAE requests
                              alen = sizeof(addr);
                              s = recvfromto(daefd, buf, sizeof(buf), MSG_WAITALL, (struct sockaddr *) &addr, &alen, &local);
                              if (s > 0) processdae(buf, s, &addr, alen, &local);
                              n--;
                              break;

                        case FD_TYPE_RADIUS: // RADIUS response
                              alen = sizeof(addr);
                              s = recvfrom(radfds[d->index], buf, sizeof(buf), MSG_WAITALL, (struct sockaddr *) &addr, &alen);
                              if (s >= 0 && config->cluster_iam_master)
                              {
                                    if (addr.sin_addr.s_addr == config->radiusserver[0] ||
                                        addr.sin_addr.s_addr == config->radiusserver[1])
                                          processrad(buf, s, d->index);
                                    else
                                          LOG(3, 0, 0, "Dropping RADIUS packet from unknown source %s\n",
                                                fmtaddr(addr.sin_addr.s_addr, 0));
                              }

                              n--;
                              break;

#ifdef BGP
                        case FD_TYPE_BGP:
                              bgp_events[d->index] = events[i].events;
                              n--;
                              break;
#endif /* BGP */

                        default:
                              LOG(0, 0, 0, "Unexpected fd type returned from epoll_wait: %d\n", d->type);
                        }
                  }

#ifdef BGP
                  bgp_process(bgp_events);
#endif /* BGP */

                  for (c = 0; n && c < config->multi_read_count; c++)
                  {
                        // L2TP
                        if (udp_ready)
                        {
                              alen = sizeof(addr);
                              if ((s = recvfrom(udpfd, buf, sizeof(buf), 0, (void *) &addr, &alen)) > 0)
                              {
                                    processudp(buf, s, &addr);
                                    udp_pkts++;
                              }
                              else
                              {
                                    udp_ready = 0;
                                    n--;
                              }
                        }

                        // incoming IP
                        if (tun_ready)
                        {
                              if ((s = read(tunfd, buf, sizeof(buf))) > 0)
                              {
                                    processtun(buf, s);
                                    tun_pkts++;
                              }
                              else
                              {
                                    tun_ready = 0;
                                    n--;
                              }
                        }

                        // cluster
                        if (cluster_ready)
                        {
                              alen = sizeof(addr);
                              if ((s = recvfrom(cluster_sockfd, buf, sizeof(buf), MSG_WAITALL, (void *) &addr, &alen)) > 0)
                              {
                                    processcluster(buf, s, addr.sin_addr.s_addr);
                                    cluster_pkts++;
                              }
                              else
                              {
                                    cluster_ready = 0;
                                    n--;
                              }
                        }
                  }

                  if (udp_pkts > 1 || tun_pkts > 1 || cluster_pkts > 1)
                        STAT(multi_read_used);

                  if (c >= config->multi_read_count)
                  {
                        LOG(3, 0, 0, "Reached multi_read_count (%d); processed %d udp, %d tun and %d cluster packets\n",
                              config->multi_read_count, udp_pkts, tun_pkts, cluster_pkts);

                        STAT(multi_read_exceeded);
                        more++;
                  }
            }

            if (time_changed)
            {
                  double Mbps = 1024.0 * 1024.0 / 8 * time_changed;

                  // Log current traffic stats
                  snprintf(config->bandwidth, sizeof(config->bandwidth),
                        "UDP-ETH:%1.0f/%1.0f  ETH-UDP:%1.0f/%1.0f  TOTAL:%0.1f   IN:%u OUT:%u",
                        (udp_rx / Mbps), (eth_tx / Mbps), (eth_rx / Mbps), (udp_tx / Mbps),
                        ((udp_tx + udp_rx + eth_tx + eth_rx) / Mbps),
                        udp_rx_pkt / time_changed, eth_rx_pkt / time_changed);
             
                  udp_tx = udp_rx = 0;
                  udp_rx_pkt = eth_rx_pkt = 0;
                  eth_tx = eth_rx = 0;
                  time_changed = 0;
             
                  if (config->dump_speed)
                        printf("%s\n", config->bandwidth);
             
                  // Update the internal time counter
                  strftime(time_now_string, sizeof(time_now_string), "%Y-%m-%d %H:%M:%S", localtime(&time_now));
             
                  {
                        // Run timer hooks
                        struct param_timer p = { time_now };
                        run_plugins(PLUGIN_TIMER, &p);
                  }
            }

                  // Runs on every machine (master and slaves).
            if (next_cluster_ping <= TIME)
            {
                  // Check to see which of the cluster is still alive..

                  cluster_send_ping(basetime);  // Only does anything if we're a slave
                  cluster_check_master();       // ditto.

                  cluster_heartbeat();          // Only does anything if we're a master.
                  cluster_check_slaves();       // ditto.

                  master_update_counts();       // If we're a slave, send our byte counters to our master.

                  if (config->cluster_iam_master && !config->cluster_iam_uptodate)
                        next_cluster_ping = TIME + 1; // out-of-date slaves, do fast updates
                  else
                        next_cluster_ping = TIME + config->cluster_hb_interval;
            }

            if (!config->cluster_iam_master)
                  continue;

                  // Run token bucket filtering queue..
                  // Only run it every 1/10th of a second.
            {
                  static clockt last_run = 0;
                  if (last_run != TIME)
                  {
                        last_run = TIME;
                        tbf_run_timer();
                  }
            }

                  // Handle timeouts, retries etc.
            {
                  static double last_clean = 0;
                  double this_clean;
                  double diff;

                  TIME = now(&this_clean);
                  diff = this_clean - last_clean;

                  // Run during idle time (after we've handled
                  // all incoming packets) or every 1/10th sec
                  if (!more || diff > 0.1)
                  {
                        regular_cleanups(diff);
                        last_clean = this_clean;
                  }
            }

            if (*config->accounting_dir)
            {
                  static clockt next_acct = 0;
                  static clockt next_shut_acct = 0;

                  if (next_acct <= TIME)
                  {
                        // Dump accounting data
                        next_acct = TIME + ACCT_TIME;
                        next_shut_acct = TIME + ACCT_SHUT_TIME;
                        dump_acct_info(1);
                  }
                  else if (next_shut_acct <= TIME)
                  {
                        // Dump accounting data for shutdown sessions
                        next_shut_acct = TIME + ACCT_SHUT_TIME;
                        if (shut_acct_n)
                              dump_acct_info(0);
                  }
            }
      }

            // Are we the master and shutting down??
      if (config->cluster_iam_master)
            cluster_heartbeat(); // Flush any queued changes..

            // Ok. Notify everyone we're shutting down. If we're
            // the master, this will force an election.
      cluster_send_ping(0);

      //
      // Important!!! We MUST not process any packets past this point!
      LOG(1, 0, 0, "Shutdown complete\n");
}

static void stripdomain(char *host)
{
      char *p;

      if ((p = strchr(host, '.')))
      {
            char *domain = 0;
            char _domain[1024];

            // strip off domain
            FILE *resolv = fopen("/etc/resolv.conf", "r");
            if (resolv)
            {
                  char buf[1024];
                  char *b;

                  while (fgets(buf, sizeof(buf), resolv))
                  {
                        if (strncmp(buf, "domain", 6) && strncmp(buf, "search", 6))
                              continue;

                        if (!isspace(buf[6]))
                              continue;

                        b = buf + 7;
                        while (isspace(*b)) b++;

                        if (*b)
                        {
                              char *d = b;
                              while (*b && !isspace(*b)) b++;
                              *b = 0;
                              if (buf[0] == 'd') // domain is canonical
                              {
                                    domain = d;
                                    break;
                              }

                              // first search line
                              if (!domain)
                              {
                                    // hold, may be subsequent domain line
                                    strncpy(_domain, d, sizeof(_domain))[sizeof(_domain)-1] = 0;
                                    domain = _domain;
                              }
                        }
                  }

                  fclose(resolv);
            }

            if (domain)
            {
                  int hl = strlen(host);
                  int dl = strlen(domain);
                  if (dl < hl && host[hl - dl - 1] == '.' && !strcmp(host + hl - dl, domain))
                        host[hl -dl - 1] = 0;
            }
            else
            {
                  *p = 0; // everything after first dot
            }
      }
}

// Init data structures
static void initdata(int optdebug, char *optconfig)
{
      int i;

      if (!(config = shared_malloc(sizeof(configt))))
      {
            fprintf(stderr, "Error doing malloc for configuration: %s\n", strerror(errno));
            exit(1);
      }

      memset(config, 0, sizeof(configt));
      time(&config->start_time);
      strncpy(config->config_file, optconfig, strlen(optconfig));
      config->debug = optdebug;
      config->num_tbfs = MAXTBFS;
      config->rl_rate = 28; // 28kbps
      config->cluster_mcast_ttl = 1;
      config->cluster_master_min_adv = 1;
      config->ppp_restart_time = 3;
      config->ppp_max_configure = 10;
      config->ppp_max_failure = 5;
      strcpy(config->random_device, RANDOMDEVICE);

      log_stream = stderr;

#ifdef RINGBUFFER
      if (!(ringbuffer = shared_malloc(sizeof(struct Tringbuffer))))
      {
            LOG(0, 0, 0, "Error doing malloc for ringbuffer: %s\n", strerror(errno));
            exit(1);
      }
      memset(ringbuffer, 0, sizeof(struct Tringbuffer));
#endif

      if (!(_statistics = shared_malloc(sizeof(struct Tstats))))
      {
            LOG(0, 0, 0, "Error doing malloc for _statistics: %s\n", strerror(errno));
            exit(1);
      }
      if (!(tunnel = shared_malloc(sizeof(tunnelt) * MAXTUNNEL)))
      {
            LOG(0, 0, 0, "Error doing malloc for tunnels: %s\n", strerror(errno));
            exit(1);
      }
      if (!(session = shared_malloc(sizeof(sessiont) * MAXSESSION)))
      {
            LOG(0, 0, 0, "Error doing malloc for sessions: %s\n", strerror(errno));
            exit(1);
      }

      if (!(sess_local = shared_malloc(sizeof(sessionlocalt) * MAXSESSION)))
      {
            LOG(0, 0, 0, "Error doing malloc for sess_local: %s\n", strerror(errno));
            exit(1);
      }

      if (!(radius = shared_malloc(sizeof(radiust) * MAXRADIUS)))
      {
            LOG(0, 0, 0, "Error doing malloc for radius: %s\n", strerror(errno));
            exit(1);
      }

      if (!(ip_address_pool = shared_malloc(sizeof(ippoolt) * MAXIPPOOL)))
      {
            LOG(0, 0, 0, "Error doing malloc for ip_address_pool: %s\n", strerror(errno));
            exit(1);
      }

      if (!(ip_filters = shared_malloc(sizeof(ip_filtert) * MAXFILTER)))
      {
            LOG(0, 0, 0, "Error doing malloc for ip_filters: %s\n", strerror(errno));
            exit(1);
      }
      memset(ip_filters, 0, sizeof(ip_filtert) * MAXFILTER);

      if (!(cli_session_actions = shared_malloc(sizeof(struct cli_session_actions) * MAXSESSION)))
      {
            LOG(0, 0, 0, "Error doing malloc for cli session actions: %s\n", strerror(errno));
            exit(1);
      }
      memset(cli_session_actions, 0, sizeof(struct cli_session_actions) * MAXSESSION);

      if (!(cli_tunnel_actions = shared_malloc(sizeof(struct cli_tunnel_actions) * MAXSESSION)))
      {
            LOG(0, 0, 0, "Error doing malloc for cli tunnel actions: %s\n", strerror(errno));
            exit(1);
      }
      memset(cli_tunnel_actions, 0, sizeof(struct cli_tunnel_actions) * MAXSESSION);

      memset(tunnel, 0, sizeof(tunnelt) * MAXTUNNEL);
      memset(session, 0, sizeof(sessiont) * MAXSESSION);
      memset(radius, 0, sizeof(radiust) * MAXRADIUS);
      memset(ip_address_pool, 0, sizeof(ippoolt) * MAXIPPOOL);

            // Put all the sessions on the free list marked as undefined.
      for (i = 1; i < MAXSESSION; i++)
      {
            session[i].next = i + 1;
            session[i].tunnel = T_UNDEF;  // mark it as not filled in.
      }
      session[MAXSESSION - 1].next = 0;
      sessionfree = 1;

            // Mark all the tunnels as undefined (waiting to be filled in by a download).
      for (i = 1; i < MAXTUNNEL; i++)
            tunnel[i].state = TUNNELUNDEF;      // mark it as not filled in.

      if (!*hostname)
      {
            // Grab my hostname unless it's been specified
            gethostname(hostname, sizeof(hostname));
            stripdomain(hostname);
      }

      _statistics->start_time = _statistics->last_reset = time(NULL);

#ifdef BGP
      if (!(bgp_peers = shared_malloc(sizeof(struct bgp_peer) * BGP_NUM_PEERS)))
      {
            LOG(0, 0, 0, "Error doing malloc for bgp: %s\n", strerror(errno));
            exit(1);
      }
#endif /* BGP */
}

static int assign_ip_address(sessionidt s)
{
      uint32_t i;
      int best = -1;
      time_t best_time = time_now;
      char *u = session[s].user;
      char reuse = 0;


      CSTAT(assign_ip_address);

      for (i = 1; i < ip_pool_size; i++)
      {
            if (!ip_address_pool[i].address || ip_address_pool[i].assigned)
                  continue;

            if (!session[s].walled_garden && ip_address_pool[i].user[0] && !strcmp(u, ip_address_pool[i].user))
            {
                  best = i;
                  reuse = 1;
                  break;
            }

            if (ip_address_pool[i].last < best_time)
            {
                  best = i;
                  if (!(best_time = ip_address_pool[i].last))
                        break; // never used, grab this one
            }
      }

      if (best < 0)
      {
            LOG(0, s, session[s].tunnel, "assign_ip_address(): out of addresses\n");
            return 0;
      }

      session[s].ip = ip_address_pool[best].address;
      session[s].ip_pool_index = best;
      ip_address_pool[best].assigned = 1;
      ip_address_pool[best].last = time_now;
      ip_address_pool[best].session = s;
      if (session[s].walled_garden)
            /* Don't track addresses of users in walled garden (note: this
               means that their address isn't "sticky" even if they get
               un-gardened). */
            ip_address_pool[best].user[0] = 0;
      else
            strncpy(ip_address_pool[best].user, u, sizeof(ip_address_pool[best].user) - 1);

      STAT(ip_allocated);
      LOG(4, s, session[s].tunnel, "assign_ip_address(): %s ip address %d from pool\n",
            reuse ? "Reusing" : "Allocating", best);

      return 1;
}

static void free_ip_address(sessionidt s)
{
      int i = session[s].ip_pool_index;


      CSTAT(free_ip_address);

      if (!session[s].ip)
            return; // what the?

      if (i < 0)  // Is this actually part of the ip pool?
            i = 0;

      STAT(ip_freed);
      cache_ipmap(session[s].ip, -i);     // Change the mapping to point back to the ip pool index.
      session[s].ip = 0;
      ip_address_pool[i].assigned = 0;
      ip_address_pool[i].session = 0;
      ip_address_pool[i].last = time_now;
}

//
// Fsck the address pool against the session table.
// Normally only called when we become a master.
//
// This isn't perfect: We aren't keep tracking of which
// users used to have an IP address.
//
void rebuild_address_pool(void)
{
      int i;

            //
            // Zero the IP pool allocation, and build
            // a map from IP address to pool index.
      for (i = 1; i < MAXIPPOOL; ++i)
      {
            ip_address_pool[i].assigned = 0;
            ip_address_pool[i].session = 0;
            if (!ip_address_pool[i].address)
                  continue;

            cache_ipmap(ip_address_pool[i].address, -i);    // Map pool IP to pool index.
      }

      for (i = 0; i < MAXSESSION; ++i)
      {
            int ipid;
            if (!(session[i].opened && session[i].ip))
                  continue;

            ipid = - lookup_ipmap(htonl(session[i].ip));

            if (session[i].ip_pool_index < 0)
            {
                  // Not allocated out of the pool.
                  if (ipid < 1)                 // Not found in the pool either? good.
                        continue;

                  LOG(0, i, 0, "Session %d has an IP address (%s) that was marked static, but is in the pool (%d)!\n",
                        i, fmtaddr(session[i].ip, 0), ipid);

                  // Fall through and process it as part of the pool.
            }


            if (ipid > MAXIPPOOL || ipid < 0)
            {
                  LOG(0, i, 0, "Session %d has a pool IP that's not found in the pool! (%d)\n", i, ipid);
                  ipid = -1;
                  session[i].ip_pool_index = ipid;
                  continue;
            }

            ip_address_pool[ipid].assigned = 1;
            ip_address_pool[ipid].session = i;
            ip_address_pool[ipid].last = time_now;
            strncpy(ip_address_pool[ipid].user, session[i].user, sizeof(ip_address_pool[ipid].user) - 1);
            session[i].ip_pool_index = ipid;
            cache_ipmap(session[i].ip, i);      // Fix the ip map.
      }
}

//
// Fix the address pool to match a changed session.
// (usually when the master sends us an update).
static void fix_address_pool(int sid)
{
      int ipid;

      ipid = session[sid].ip_pool_index;

      if (ipid > ip_pool_size)
            return;           // Ignore it. rebuild_address_pool will fix it up.

      if (ip_address_pool[ipid].address != session[sid].ip)
            return;           // Just ignore it. rebuild_address_pool will take care of it.

      ip_address_pool[ipid].assigned = 1;
      ip_address_pool[ipid].session = sid;
      ip_address_pool[ipid].last = time_now;
      strncpy(ip_address_pool[ipid].user, session[sid].user, sizeof(ip_address_pool[ipid].user) - 1);
}

//
// Add a block of addresses to the IP pool to hand out.
//
static void add_to_ip_pool(in_addr_t addr, in_addr_t mask)
{
      int i;
      if (mask == 0)
            mask = 0xffffffff;      // Host route only.

      addr &= mask;

      if (ip_pool_size >= MAXIPPOOL)      // Pool is full!
            return ;

      for (i = addr ;(i & mask) == addr; ++i)
      {
            if ((i & 0xff) == 0 || (i&0xff) == 255)
                  continue;   // Skip 0 and broadcast addresses.

            ip_address_pool[ip_pool_size].address = i;
            ip_address_pool[ip_pool_size].assigned = 0;
            ++ip_pool_size;
            if (ip_pool_size >= MAXIPPOOL)
            {
                  LOG(0, 0, 0, "Overflowed IP pool adding %s\n", fmtaddr(htonl(addr), 0));
                  return;
            }
      }
}

// Initialize the IP address pool
static void initippool()
{
      FILE *f;
      char *p;
      char buf[4096];
      memset(ip_address_pool, 0, sizeof(ip_address_pool));

      if (!(f = fopen(IPPOOLFILE, "r")))
      {
            LOG(0, 0, 0, "Can't load pool file " IPPOOLFILE ": %s\n", strerror(errno));
            exit(1);
      }

      while (ip_pool_size < MAXIPPOOL && fgets(buf, 4096, f))
      {
            char *pool = buf;
            buf[4095] = 0;    // Force it to be zero terminated/

            if (*buf == '#' || *buf == '\n')
                  continue; // Skip comments / blank lines
            if ((p = (char *)strrchr(buf, '\n'))) *p = 0;
            if ((p = (char *)strchr(buf, ':')))
            {
                  in_addr_t src;
                  *p = '\0';
                  src = inet_addr(buf);
                  if (src == INADDR_NONE)
                  {
                        LOG(0, 0, 0, "Invalid address pool IP %s\n", buf);
                        exit(1);
                  }
                  // This entry is for a specific IP only
                  if (src != config->bind_address)
                        continue;
                  *p = ':';
                  pool = p+1;
            }
            if ((p = (char *)strchr(pool, '/')))
            {
                  // It's a range
                  int numbits = 0;
                  in_addr_t start = 0, mask = 0;

                  LOG(2, 0, 0, "Adding IP address range %s\n", buf);
                  *p++ = 0;
                  if (!*p || !(numbits = atoi(p)))
                  {
                        LOG(0, 0, 0, "Invalid pool range %s\n", buf);
                        continue;
                  }
                  start = ntohl(inet_addr(pool));
                  mask = (in_addr_t) (pow(2, numbits) - 1) << (32 - numbits);

                  // Add a static route for this pool
                  LOG(5, 0, 0, "Adding route for address pool %s/%u\n",
                        fmtaddr(htonl(start), 0), 32 + mask);

                  routeset(0, start, mask, 0, 1);

                  add_to_ip_pool(start, mask);
            }
            else
            {
                  // It's a single ip address
                  add_to_ip_pool(ntohl(inet_addr(pool)), 0);
            }
      }
      fclose(f);
      LOG(1, 0, 0, "IP address pool is %d addresses\n", ip_pool_size - 1);
}

void snoop_send_packet(uint8_t *packet, uint16_t size, in_addr_t destination, uint16_t port)
{
      struct sockaddr_in snoop_addr = {0};
      if (!destination || !port || snoopfd <= 0 || size <= 0 || !packet)
            return;

      snoop_addr.sin_family = AF_INET;
      snoop_addr.sin_addr.s_addr = destination;
      snoop_addr.sin_port = ntohs(port);

      LOG(5, 0, 0, "Snooping %d byte packet to %s:%d\n", size,
            fmtaddr(snoop_addr.sin_addr.s_addr, 0),
            htons(snoop_addr.sin_port));

      if (sendto(snoopfd, packet, size, MSG_DONTWAIT | MSG_NOSIGNAL, (void *) &snoop_addr, sizeof(snoop_addr)) < 0)
            LOG(0, 0, 0, "Error sending intercept packet: %s\n", strerror(errno));

      STAT(packets_snooped);
}

static int dump_session(FILE **f, sessiont *s)
{
      if (!s->opened || !s->ip || !(s->cin_delta || s->cout_delta) || !*s->user || s->walled_garden)
            return 1;

      if (!*f)
      {
            char filename[1024];
            char timestr[64];
            time_t now = time(NULL);

            strftime(timestr, sizeof(timestr), "%Y%m%d%H%M%S", localtime(&now));
            snprintf(filename, sizeof(filename), "%s/%s", config->accounting_dir, timestr);

            if (!(*f = fopen(filename, "w")))
            {
                  LOG(0, 0, 0, "Can't write accounting info to %s: %s\n", filename, strerror(errno));
                  return 0;
            }

            LOG(3, 0, 0, "Dumping accounting information to %s\n", filename);
            fprintf(*f, "# dslwatch.pl dump file V1.01\n"
                  "# host: %s\n"
                  "# endpoint: %s\n"
                  "# time: %ld\n"
                  "# uptime: %ld\n"
                  "# format: username ip qos uptxoctets downrxoctets\n",
                  hostname,
                  fmtaddr(config->bind_address ? config->bind_address : my_address, 0),
                  now,
                  now - basetime);
      }

      LOG(4, 0, 0, "Dumping accounting information for %s\n", s->user);
      fprintf(*f, "%s %s %d %u %u\n",
            s->user,                                  // username
            fmtaddr(htonl(s->ip), 0),                       // ip
            (s->throttle_in || s->throttle_out) ? 2 : 1,          // qos
            (uint32_t) s->cin_delta,                        // uptxoctets
            (uint32_t) s->cout_delta);                      // downrxoctets

      s->cin_delta = s->cout_delta = 0;

      return 1;
}

static void dump_acct_info(int all)
{
      int i;
      FILE *f = NULL;


      CSTAT(dump_acct_info);

      if (shut_acct_n)
      {
            for (i = 0; i < shut_acct_n; i++)
                  dump_session(&f, &shut_acct[i]);

            shut_acct_n = 0;
      }

      if (all)
            for (i = 1; i <= config->cluster_highest_sessionid; i++)
                  dump_session(&f, &session[i]);

      if (f)
            fclose(f);
}

// Main program
int main(int argc, char *argv[])
{
      int i;
      int optdebug = 0;
      char *optconfig = CONFIGFILE;

      time(&basetime);             // start clock

      // scan args
      while ((i = getopt(argc, argv, "dvc:h:")) >= 0)
      {
            switch (i)
            {
            case 'd':
                  if (fork()) exit(0);
                  setsid();
                  freopen("/dev/null", "r", stdin);
                  freopen("/dev/null", "w", stdout);
                  freopen("/dev/null", "w", stderr);
                  break;
            case 'v':
                  optdebug++;
                  break;
            case 'c':
                  optconfig = optarg;
                  break;
            case 'h':
                  snprintf(hostname, sizeof(hostname), "%s", optarg);
                  break;
            default:
                  printf("Args are:\n"
                         "\t-d\t\tDetach from terminal\n"
                         "\t-c <file>\tConfig file\n"
                         "\t-h <hostname>\tForce hostname\n"
                         "\t-v\t\tDebug\n");

                  return (0);
                  break;
            }
      }

      // Start the timer routine off
      time(&time_now);
      strftime(time_now_string, sizeof(time_now_string), "%Y-%m-%d %H:%M:%S", localtime(&time_now));

      initplugins();
      initdata(optdebug, optconfig);

      init_cli(hostname);
      read_config_file();
      update_config();
      init_tbf(config->num_tbfs);

      LOG(0, 0, 0, "L2TPNS version " VERSION "\n");
      LOG(0, 0, 0, "Copyright (c) 2003, 2004, 2005 Optus Internet Engineering\n");
      LOG(0, 0, 0, "Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced\n");
      {
            struct rlimit rlim;
            rlim.rlim_cur = RLIM_INFINITY;
            rlim.rlim_max = RLIM_INFINITY;
            // Remove the maximum core size
            if (setrlimit(RLIMIT_CORE, &rlim) < 0)
                  LOG(0, 0, 0, "Can't set ulimit: %s\n", strerror(errno));

            // Make core dumps go to /tmp
            chdir("/tmp");
      }

      if (config->scheduler_fifo)
      {
            int ret;
            struct sched_param params = {0};
            params.sched_priority = 1;

            if (get_nprocs() < 2)
            {
                  LOG(0, 0, 0, "Not using FIFO scheduler, there is only 1 processor in the system.\n");
                  config->scheduler_fifo = 0;
            }
            else
            {
                  if ((ret = sched_setscheduler(0, SCHED_FIFO, &params)) == 0)
                  {
                        LOG(1, 0, 0, "Using FIFO scheduler.  Say goodbye to any other processes running\n");
                  }
                  else
                  {
                        LOG(0, 0, 0, "Error setting scheduler to FIFO: %s\n", strerror(errno));
                        config->scheduler_fifo = 0;
                  }
            }
      }

      /* Set up the cluster communications port. */
      if (cluster_init() < 0)
            exit(1);

      inittun();
      LOG(1, 0, 0, "Set up on interface %s\n", config->tundevice);

      initudp();
      initrad();
      initippool();

      // seed prng
      {
            unsigned seed = time_now ^ getpid();
            LOG(4, 0, 0, "Seeding the pseudo random generator: %u\n", seed);
            srand(seed);
      }

      signal(SIGHUP,  sighup_handler);
      signal(SIGCHLD, sigchild_handler);
      signal(SIGTERM, shutdown_handler);
      signal(SIGINT,  shutdown_handler);
      signal(SIGQUIT, shutdown_handler);

      // Prevent us from getting paged out
      if (config->lock_pages)
      {
            if (!mlockall(MCL_CURRENT))
                  LOG(1, 0, 0, "Locking pages into memory\n");
            else
                  LOG(0, 0, 0, "Can't lock pages: %s\n", strerror(errno));
      }

      // Drop privileges here
      if (config->target_uid > 0 && geteuid() == 0)
            setuid(config->target_uid);

      mainloop();

      /* remove plugins (so cleanup code gets run) */
      plugins_done();

      // Remove the PID file if we wrote it
      if (config->wrote_pid && *config->pid_file == '/')
            unlink(config->pid_file);

      /* kill CLI children */
      signal(SIGTERM, SIG_IGN);
      kill(0, SIGTERM);
      return 0;
}

static void sighup_handler(int sig)
{
      main_reload++;
}

static void shutdown_handler(int sig)
{
      main_quit = (sig == SIGQUIT) ? QUIT_SHUTDOWN : QUIT_FAILOVER;
}

static void sigchild_handler(int sig)
{
      while (waitpid(-1, NULL, WNOHANG) > 0)
          ;
}

static void build_chap_response(uint8_t *challenge, uint8_t id, uint16_t challenge_length, uint8_t **challenge_response)
{
      MD5_CTX ctx;
      *challenge_response = NULL;

      if (!*config->l2tp_secret)
      {
            LOG(0, 0, 0, "LNS requested CHAP authentication, but no l2tp secret is defined\n");
            return;
      }

      LOG(4, 0, 0, "   Building challenge response for CHAP request\n");

      *challenge_response = calloc(17, 1);

      MD5_Init(&ctx);
      MD5_Update(&ctx, &id, 1);
      MD5_Update(&ctx, config->l2tp_secret, strlen(config->l2tp_secret));
      MD5_Update(&ctx, challenge, challenge_length);
      MD5_Final(*challenge_response, &ctx);

      return;
}

static int facility_value(char *name)
{
      int i;
      for (i = 0; facilitynames[i].c_name; i++)
      {
            if (strcmp(facilitynames[i].c_name, name) == 0)
                  return facilitynames[i].c_val;
      }
      return 0;
}

static void update_config()
{
      int i;
      char *p;
      static int timeout = 0;
      static int interval = 0;

      // Update logging
      closelog();
      syslog_log = 0;
      if (log_stream)
      {
            if (log_stream != stderr)
                  fclose(log_stream);

            log_stream = NULL;
      }

      if (*config->log_filename)
      {
            if (strstr(config->log_filename, "syslog:") == config->log_filename)
            {
                  char *p = config->log_filename + 7;
                  if (*p)
                  {
                        openlog("l2tpns", LOG_PID, facility_value(p));
                        syslog_log = 1;
                  }
            }
            else if (strchr(config->log_filename, '/') == config->log_filename)
            {
                  if ((log_stream = fopen((char *)(config->log_filename), "a")))
                  {
                        fseek(log_stream, 0, SEEK_END);
                        setbuf(log_stream, NULL);
                  }
                  else
                  {
                        log_stream = stderr;
                        setbuf(log_stream, NULL);
                  }
            }
      }
      else
      {
            log_stream = stderr;
            setbuf(log_stream, NULL);
      }

#define L2TP_HDRS       (20+8+6+4)  // L2TP data encaptulation: ip + udp + l2tp (data) + ppp (inc hdlc)
#define TCP_HDRS        (20+20)           // TCP encapsulation: ip + tcp

      if (config->l2tp_mtu <= 0)          config->l2tp_mtu = 1500; // ethernet default
      else if (config->l2tp_mtu < MINMTU) config->l2tp_mtu = MINMTU;
      else if (config->l2tp_mtu > MAXMTU) config->l2tp_mtu = MAXMTU;

      // reset MRU/MSS globals
      MRU = config->l2tp_mtu - L2TP_HDRS;
      if (MRU > PPPoE_MRU)
            MRU = PPPoE_MRU;

      MSS = MRU - TCP_HDRS;

      // Update radius
      config->numradiusservers = 0;
      for (i = 0; i < MAXRADSERVER; i++)
            if (config->radiusserver[i])
            {
                  config->numradiusservers++;
                  // Set radius port: if not set, take the port from the
                  // first radius server.  For the first radius server,
                  // take the #defined default value from l2tpns.h

                  // test twice, In case someone works with
                  // a secondary radius server without defining
                  // a primary one, this will work even then.
                  if (i > 0 && !config->radiusport[i])
                        config->radiusport[i] = config->radiusport[i-1];
                  if (!config->radiusport[i])
                        config->radiusport[i] = RADPORT;
            }

      if (!config->numradiusservers)
            LOG(0, 0, 0, "No RADIUS servers defined!\n");

      // parse radius_authtypes_s
      config->radius_authtypes = config->radius_authprefer = 0;
      p = config->radius_authtypes_s;
      while (p && *p)
      {
            char *s = strpbrk(p, " \t,");
            int type = 0;

            if (s)
            {
                  *s++ = 0;
                  while (*s == ' ' || *s == '\t')
                        s++;

                  if (!*s)
                        s = 0;
            }

            if (!strncasecmp("chap", p, strlen(p)))
                  type = AUTHCHAP;
            else if (!strncasecmp("pap", p, strlen(p)))
                  type = AUTHPAP;
            else
                  LOG(0, 0, 0, "Invalid RADIUS authentication type \"%s\"\n", p);

            config->radius_authtypes |= type;
            if (!config->radius_authprefer)
                  config->radius_authprefer = type;

            p = s;
      }

      if (!config->radius_authtypes)
      {
            LOG(0, 0, 0, "Defaulting to PAP authentication\n");
            config->radius_authtypes = config->radius_authprefer = AUTHPAP;
      }

      // normalise radius_authtypes_s
      if (config->radius_authprefer == AUTHPAP)
      {
            strcpy(config->radius_authtypes_s, "pap");
            if (config->radius_authtypes & AUTHCHAP)
                  strcat(config->radius_authtypes_s, ", chap");
      }
      else
      {
            strcpy(config->radius_authtypes_s, "chap");
            if (config->radius_authtypes & AUTHPAP)
                  strcat(config->radius_authtypes_s, ", pap");
      }

      if (!config->radius_dae_port)
            config->radius_dae_port = DAEPORT;

      // re-initialise the random number source
      initrandom(config->random_device);

      // Update plugins
      for (i = 0; i < MAXPLUGINS; i++)
      {
            if (strcmp(config->plugins[i], config->old_plugins[i]) == 0)
                  continue;

            if (*config->plugins[i])
            {
                  // Plugin added
                  add_plugin(config->plugins[i]);
            }
            else if (*config->old_plugins[i])
            {
                  // Plugin removed
                  remove_plugin(config->old_plugins[i]);
            }
      }

      memcpy(config->old_plugins, config->plugins, sizeof(config->plugins));
      if (!config->multi_read_count) config->multi_read_count = 10;
      if (!config->cluster_address) config->cluster_address = inet_addr(DEFAULT_MCAST_ADDR);
      if (!*config->cluster_interface)
            strncpy(config->cluster_interface, DEFAULT_MCAST_INTERFACE, sizeof(config->cluster_interface) - 1);

      if (!config->cluster_hb_interval)
            config->cluster_hb_interval = PING_INTERVAL;    // Heartbeat every 0.5 seconds.

      if (!config->cluster_hb_timeout)
            config->cluster_hb_timeout = HB_TIMEOUT;  // 10 missed heartbeat triggers an election.

      if (interval != config->cluster_hb_interval || timeout != config->cluster_hb_timeout)
      {
            // Paranoia:  cluster_check_master() treats 2 x interval + 1 sec as
            // late, ensure we're sufficiently larger than that
            int t = 4 * config->cluster_hb_interval + 11;

            if (config->cluster_hb_timeout < t)
            {
                  LOG(0, 0, 0, "Heartbeat timeout %d too low, adjusting to %d\n", config->cluster_hb_timeout, t);
                  config->cluster_hb_timeout = t;
            }

            // Push timing changes to the slaves immediately if we're the master
            if (config->cluster_iam_master)
                  cluster_heartbeat();

            interval = config->cluster_hb_interval;
            timeout = config->cluster_hb_timeout;
      }

      // Write PID file
      if (*config->pid_file == '/' && !config->wrote_pid)
      {
            FILE *f;
            if ((f = fopen(config->pid_file, "w")))
            {
                  fprintf(f, "%d\n", getpid());
                  fclose(f);
                  config->wrote_pid = 1;
            }
            else
            {
                  LOG(0, 0, 0, "Can't write to PID file %s: %s\n", config->pid_file, strerror(errno));
            }
      }
}

static void read_config_file()
{
      FILE *f;

      if (!config->config_file) return;
      if (!(f = fopen(config->config_file, "r")))
      {
            fprintf(stderr, "Can't open config file %s: %s\n", config->config_file, strerror(errno));
            return;
      }

      LOG(3, 0, 0, "Reading config file %s\n", config->config_file);
      cli_do_file(f);
      LOG(3, 0, 0, "Done reading config file\n");
      fclose(f);
}

int sessionsetup(sessionidt s, tunnelidt t)
{
      // A session now exists, set it up
      in_addr_t ip;
      char *user;
      sessionidt i;
      int r;

      CSTAT(sessionsetup);

      LOG(3, s, t, "Doing session setup for session\n");

      if (!session[s].ip)
      {
            assign_ip_address(s);
            if (!session[s].ip)
            {
                  LOG(0, s, t, "   No IP allocated.  The IP address pool is FULL!\n");
                  sessionshutdown(s, "No IP addresses available.", CDN_TRY_ANOTHER, TERM_SERVICE_UNAVAILABLE);
                  return 0;
            }
            LOG(3, s, t, "   No IP allocated.  Assigned %s from pool\n",
                  fmtaddr(htonl(session[s].ip), 0));
      }


      // Make sure this is right
      session[s].tunnel = t;

      // zap old sessions with same IP and/or username
      // Don't kill gardened sessions - doing so leads to a DoS
      // from someone who doesn't need to know the password
      {
            ip = session[s].ip;
            user = session[s].user;
            for (i = 1; i <= config->cluster_highest_sessionid; i++)
            {
                  if (i == s) continue;
                  if (!session[s].opened) continue;
                  if (ip == session[i].ip)
                  {
                        sessionkill(i, "Duplicate IP address");
                        continue;
                  }

                  if (config->allow_duplicate_users) continue;
                  if (session[s].walled_garden || session[i].walled_garden) continue;
                  if (!strcasecmp(user, session[i].user))
                        sessionkill(i, "Duplicate session for users");
            }
      }

      {
            int routed = 0;

            // Add the route for this session.
            for (r = 0; r < MAXROUTE && session[s].route[r].ip; r++)
            {
                  if ((session[s].ip & session[s].route[r].mask) ==
                      (session[s].route[r].ip & session[s].route[r].mask))
                        routed++;

                  routeset(s, session[s].route[r].ip, session[s].route[r].mask, 0, 1);
            }

            // Static IPs need to be routed if not already
            // convered by a Framed-Route.  Anything else is part
            // of the IP address pool and is already routed, it
            // just needs to be added to the IP cache.
            // IPv6 route setup is done in ppp.c, when IPV6CP is acked.
            if (session[s].ip_pool_index == -1) // static ip
            {
                  if (!routed) routeset(s, session[s].ip, 0, 0, 1);
            }
            else
                  cache_ipmap(session[s].ip, s);
      }

      sess_local[s].lcp_authtype = 0; // RADIUS authentication complete
      lcp_open(s, t); // transition to Network phase and send initial IPCP

      // Run the plugin's against this new session.
      {
            struct param_new_session data = { &tunnel[t], &session[s] };
            run_plugins(PLUGIN_NEW_SESSION, &data);
      }

      // Allocate TBFs if throttled
      if (session[s].throttle_in || session[s].throttle_out)
            throttle_session(s, session[s].throttle_in, session[s].throttle_out);

      session[s].last_packet = time_now;

      LOG(2, s, t, "Login by %s at %s from %s (%s)\n", session[s].user,
            fmtaddr(htonl(session[s].ip), 0),
            fmtaddr(htonl(tunnel[t].ip), 1), tunnel[t].hostname);

      cluster_send_session(s);      // Mark it as dirty, and needing to the flooded to the cluster.

      return 1;       // RADIUS OK and IP allocated, done...
}

//
// This session just got dropped on us by the master or something.
// Make sure our tables up up to date...
//
int load_session(sessionidt s, sessiont *new)
{
      int i;
      int newip = 0;

            // Sanity checks.
      if (new->ip_pool_index >= MAXIPPOOL ||
            new->tunnel >= MAXTUNNEL)
      {
            LOG(0, s, 0, "Strange session update received!\n");
                  // FIXME! What to do here?
            return 0;
      }

            //
            // Ok. All sanity checks passed. Now we're committed to
            // loading the new session.
            //

      session[s].tunnel = new->tunnel; // For logging in cache_ipmap

      // See if routes/ip cache need updating
      if (new->ip != session[s].ip)
            newip++;

      for (i = 0; !newip && i < MAXROUTE && (session[s].route[i].ip || new->route[i].ip); i++)
            if (new->route[i].ip != session[s].route[i].ip ||
                new->route[i].mask != session[s].route[i].mask)
                  newip++;

      // needs update
      if (newip)
      {
            int routed = 0;

            // remove old routes...
            for (i = 0; i < MAXROUTE && session[s].route[i].ip; i++)
            {
                  if ((session[s].ip & session[s].route[i].mask) ==
                      (session[s].route[i].ip & session[s].route[i].mask))
                        routed++;

                  routeset(s, session[s].route[i].ip, session[s].route[i].mask, 0, 0);
            }

            // ...ip
            if (session[s].ip)
            {
                  if (session[s].ip_pool_index == -1) // static IP
                  {
                        if (!routed) routeset(s, session[s].ip, 0, 0, 0);
                  }
                  else        // It's part of the IP pool, remove it manually.
                        uncache_ipmap(session[s].ip);
            }

            routed = 0;

            // add new routes...
            for (i = 0; i < MAXROUTE && new->route[i].ip; i++)
            {
                  if ((new->ip & new->route[i].mask) ==
                      (new->route[i].ip & new->route[i].mask))
                        routed++;

                  routeset(s, new->route[i].ip, new->route[i].mask, 0, 1);
            }

            // ...ip
            if (new->ip)
            {
                  // If there's a new one, add it.
                  if (new->ip_pool_index == -1)
                  {
                        if (!routed) routeset(s, new->ip, 0, 0, 1);
                  }
                  else
                        cache_ipmap(new->ip, s);
            }
      }

      // check v6 routing
      if (new->ipv6prefixlen && new->ppp.ipv6cp == Opened && session[s].ppp.ipv6cp != Opened)
                route6set(s, new->ipv6route, new->ipv6prefixlen, 1);

      // check filters
      if (new->filter_in && (new->filter_in > MAXFILTER || !ip_filters[new->filter_in - 1].name[0]))
      {
            LOG(2, s, session[s].tunnel, "Dropping invalid input filter %d\n", (int) new->filter_in);
            new->filter_in = 0;
      }

      if (new->filter_out && (new->filter_out > MAXFILTER || !ip_filters[new->filter_out - 1].name[0]))
      {
            LOG(2, s, session[s].tunnel, "Dropping invalid output filter %d\n", (int) new->filter_out);
            new->filter_out = 0;
      }

      if (new->filter_in != session[s].filter_in)
      {
            if (session[s].filter_in) ip_filters[session[s].filter_in - 1].used--;
            if (new->filter_in)       ip_filters[new->filter_in - 1].used++;
      }

      if (new->filter_out != session[s].filter_out)
      {
            if (session[s].filter_out) ip_filters[session[s].filter_out - 1].used--;
            if (new->filter_out)       ip_filters[new->filter_out - 1].used++;
      }

      if (new->tunnel && s > config->cluster_highest_sessionid)   // Maintain this in the slave. It's used
                              // for walking the sessions to forward byte counts to the master.
            config->cluster_highest_sessionid = s;

      memcpy(&session[s], new, sizeof(session[s]));   // Copy over..

            // Do fixups into address pool.
      if (new->ip_pool_index != -1)
            fix_address_pool(s);

      return 1;
}

static void initplugins()
{
      int i;

      loaded_plugins = ll_init();
      // Initialize the plugins to nothing
      for (i = 0; i < MAX_PLUGIN_TYPES; i++)
            plugins[i] = ll_init();
}

static void *open_plugin(char *plugin_name, int load)
{
      char path[256] = "";

      snprintf(path, 256, PLUGINDIR "/%s.so", plugin_name);
      LOG(2, 0, 0, "%soading plugin from %s\n", load ? "L" : "Un-l", path);
      return dlopen(path, RTLD_NOW);
}

// plugin callback to get a config value
static void *getconfig(char *key, enum config_typet type)
{
      int i;

      for (i = 0; config_values[i].key; i++)
      {
            if (!strcmp(config_values[i].key, key))
            {
                  if (config_values[i].type == type)
                        return ((void *) config) + config_values[i].offset;

                  LOG(1, 0, 0, "plugin requested config item \"%s\" expecting type %d, have type %d\n",
                        key, type, config_values[i].type);

                  return 0;
            }
      }

      LOG(1, 0, 0, "plugin requested unknown config item \"%s\"\n", key);
      return 0;
}

static int add_plugin(char *plugin_name)
{
      static struct pluginfuncs funcs = {
            _log,
            _log_hex,
            fmtaddr,
            sessionbyuser,
            sessiontbysessionidt,
            sessionidtbysessiont,
            radiusnew,
            radiussend,
            getconfig,
            sessionshutdown,
            sessionkill,
            throttle_session,
            cluster_send_session,
      };

      void *p = open_plugin(plugin_name, 1);
      int (*initfunc)(struct pluginfuncs *);
      int i;

      if (!p)
      {
            LOG(1, 0, 0, "   Plugin load failed: %s\n", dlerror());
            return -1;
      }

      if (ll_contains(loaded_plugins, p))
      {
            dlclose(p);
            return 0; // already loaded
      }

      {
            int *v = dlsym(p, "plugin_api_version");
            if (!v || *v != PLUGIN_API_VERSION)
            {
                  LOG(1, 0, 0, "   Plugin load failed: API version mismatch: %s\n", dlerror());
                  dlclose(p);
                  return -1;
            }
      }

      if ((initfunc = dlsym(p, "plugin_init")))
      {
            if (!initfunc(&funcs))
            {
                  LOG(1, 0, 0, "   Plugin load failed: plugin_init() returned FALSE: %s\n", dlerror());
                  dlclose(p);
                  return -1;
            }
      }

      ll_push(loaded_plugins, p);

      for (i = 0; i < max_plugin_functions; i++)
      {
            void *x;
            if (plugin_functions[i] && (x = dlsym(p, plugin_functions[i])))
            {
                  LOG(3, 0, 0, "   Supports function \"%s\"\n", plugin_functions[i]);
                  ll_push(plugins[i], x);
            }
      }

      LOG(2, 0, 0, "   Loaded plugin %s\n", plugin_name);
      return 1;
}

static void run_plugin_done(void *plugin)
{
      int (*donefunc)(void) = dlsym(plugin, "plugin_done");

      if (donefunc)
            donefunc();
}

static int remove_plugin(char *plugin_name)
{
      void *p = open_plugin(plugin_name, 0);
      int loaded = 0;

      if (!p)
            return -1;

      if (ll_contains(loaded_plugins, p))
      {
            int i;
            for (i = 0; i < max_plugin_functions; i++)
            {
                  void *x;
                  if (plugin_functions[i] && (x = dlsym(p, plugin_functions[i])))
                        ll_delete(plugins[i], x);
            }

            ll_delete(loaded_plugins, p);
            run_plugin_done(p);
            loaded = 1;
      }

      dlclose(p);
      LOG(2, 0, 0, "Removed plugin %s\n", plugin_name);
      return loaded;
}

int run_plugins(int plugin_type, void *data)
{
      int (*func)(void *data);

      if (!plugins[plugin_type] || plugin_type > max_plugin_functions)
            return PLUGIN_RET_ERROR;

      ll_reset(plugins[plugin_type]);
      while ((func = ll_next(plugins[plugin_type])))
      {
            int r = func(data);

            if (r != PLUGIN_RET_OK)
                  return r; // stop here
      }

      return PLUGIN_RET_OK;
}

static void plugins_done()
{
      void *p;

      ll_reset(loaded_plugins);
      while ((p = ll_next(loaded_plugins)))
            run_plugin_done(p);
}

static void processcontrol(uint8_t *buf, int len, struct sockaddr_in *addr, int alen, struct in_addr *local)
{
      struct nsctl request;
      struct nsctl response;
      int type = unpack_control(&request, buf, len);
      int r;
      void *p;

      if (log_stream && config->debug >= 4)
      {
            if (type < 0)
            {
                  LOG(4, 0, 0, "Bogus control message from %s (%d)\n",
                        fmtaddr(addr->sin_addr.s_addr, 0), type);
            }
            else
            {
                  LOG(4, 0, 0, "Received [%s] ", fmtaddr(addr->sin_addr.s_addr, 0));
                  dump_control(&request, log_stream);
            }
      }

      switch (type)
      {
      case NSCTL_REQ_LOAD:
            if (request.argc != 1)
            {
                  response.type = NSCTL_RES_ERR;
                  response.argc = 1;
                  response.argv[0] = "name of plugin required";
            }
            else if ((r = add_plugin(request.argv[0])) < 1)
            {
                  response.type = NSCTL_RES_ERR;
                  response.argc = 1;
                  response.argv[0] = !r
                        ? "plugin already loaded"
                        : "error loading plugin";
            }
            else
            {
                  response.type = NSCTL_RES_OK;
                  response.argc = 0;
            }

            break;

      case NSCTL_REQ_UNLOAD:
            if (request.argc != 1)
            {
                  response.type = NSCTL_RES_ERR;
                  response.argc = 1;
                  response.argv[0] = "name of plugin required";
            }
            else if ((r = remove_plugin(request.argv[0])) < 1)
            {
                  response.type = NSCTL_RES_ERR;
                  response.argc = 1;
                  response.argv[0] = !r
                        ? "plugin not loaded"
                        : "plugin not found";
            }
            else
            {
                  response.type = NSCTL_RES_OK;
                  response.argc = 0;
            }

            break;

      case NSCTL_REQ_HELP:
            response.type = NSCTL_RES_OK;
            response.argc = 0;

            ll_reset(loaded_plugins);
            while ((p = ll_next(loaded_plugins)))
            {
                  char **help = dlsym(p, "plugin_control_help");
                  while (response.argc < 0xff && help && *help)
                        response.argv[response.argc++] = *help++;
            }

            break;

      case NSCTL_REQ_CONTROL:
            {
                  struct param_control param = {
                        config->cluster_iam_master,
                        request.argc,
                        request.argv,
                        0,
                        NULL,
                  };

                  int r = run_plugins(PLUGIN_CONTROL, &param);

                  if (r == PLUGIN_RET_ERROR)
                  {
                        response.type = NSCTL_RES_ERR;
                        response.argc = 1;
                        response.argv[0] = param.additional
                              ? param.additional
                              : "error returned by plugin";
                  }
                  else if (r == PLUGIN_RET_NOTMASTER)
                  {
                        static char msg[] = "must be run on master: 000.000.000.000";

                        response.type = NSCTL_RES_ERR;
                        response.argc = 1;
                        if (config->cluster_master_address)
                        {
                              strcpy(msg + 23, fmtaddr(config->cluster_master_address, 0));
                              response.argv[0] = msg;
                        }
                        else
                        {
                              response.argv[0] = "must be run on master: none elected";
                        }
                  }
                  else if (!(param.response & NSCTL_RESPONSE))
                  {
                        response.type = NSCTL_RES_ERR;
                        response.argc = 1;
                        response.argv[0] = param.response
                              ? "unrecognised response value from plugin"
                              : "unhandled action";
                  }
                  else
                  {
                        response.type = param.response;
                        response.argc = 0;
                        if (param.additional)
                        {
                              response.argc = 1;
                              response.argv[0] = param.additional;
                        }
                  }
            }

            break;

      default:
            response.type = NSCTL_RES_ERR;
            response.argc = 1;
            response.argv[0] = "error unpacking control packet";
      }

      buf = calloc(NSCTL_MAX_PKT_SZ, 1);
      if (!buf)
      {
            LOG(2, 0, 0, "Failed to allocate nsctl response\n");
            return;
      }

      r = pack_control(buf, NSCTL_MAX_PKT_SZ, response.type, response.argc, response.argv);
      if (r > 0)
      {
            sendtofrom(controlfd, buf, r, 0, (const struct sockaddr *) addr, alen, local);
            if (log_stream && config->debug >= 4)
            {
                  LOG(4, 0, 0, "Sent [%s] ", fmtaddr(addr->sin_addr.s_addr, 0));
                  dump_control(&response, log_stream);
            }
      }
      else
            LOG(2, 0, 0, "Failed to pack nsctl response for %s (%d)\n",
                  fmtaddr(addr->sin_addr.s_addr, 0), r);

      free(buf);
}

static tunnelidt new_tunnel()
{
      tunnelidt i;
      for (i = 1; i < MAXTUNNEL; i++)
      {
            if (tunnel[i].state == TUNNELFREE)
            {
                  LOG(4, 0, i, "Assigning tunnel ID %d\n", i);
                  if (i > config->cluster_highest_tunnelid)
                        config->cluster_highest_tunnelid = i;
                  return i;
            }
      }
      LOG(0, 0, 0, "Can't find a free tunnel! There shouldn't be this many in use!\n");
      return 0;
}

//
// We're becoming the master. Do any required setup..
//
// This is principally telling all the plugins that we're
// now a master, and telling them about all the sessions
// that are active too..
//
void become_master(void)
{
      int s, i;
      static struct event_data d[RADIUS_FDS];
      struct epoll_event e;

      run_plugins(PLUGIN_BECOME_MASTER, NULL);

      // running a bunch of iptables commands is slow and can cause
      // the master to drop tunnels on takeover--kludge around the
      // problem by forking for the moment (note: race)
      if (!fork_and_close())
      {
            for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
            {
                  if (!session[s].opened) // Not an in-use session.
                        continue;

                  run_plugins(PLUGIN_NEW_SESSION_MASTER, &session[s]);
            }
            exit(0);
      }

      // add radius fds
      e.events = EPOLLIN;
      for (i = 0; i < RADIUS_FDS; i++)
      {
            d[i].type = FD_TYPE_RADIUS;
            d[i].index = i;
            e.data.ptr = &d[i];

            epoll_ctl(epollfd, EPOLL_CTL_ADD, radfds[i], &e);
      }
}

int cmd_show_hist_idle(struct cli_def *cli, char *command, char **argv, int argc)
{
      int s, i;
      int count = 0;
      int buckets[64];

      if (CLI_HELP_REQUESTED)
            return CLI_HELP_NO_ARGS;

      time(&time_now);
      for (i = 0; i < 64;++i) buckets[i] = 0;

      for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
      {
            int idle;
            if (!session[s].opened)
                  continue;

            idle = time_now - session[s].last_packet;
            idle /= 5 ; // In multiples of 5 seconds.
            if (idle < 0)
                  idle = 0;
            if (idle > 63)
                  idle = 63;

            ++count;
            ++buckets[idle];
      }

      for (i = 0; i < 63; ++i)
      {
            cli_print(cli, "%3d seconds  : %7.2f%% (%6d)", i * 5, (double) buckets[i] * 100.0 / count , buckets[i]);
      }
      cli_print(cli, "lots of secs : %7.2f%% (%6d)", (double) buckets[63] * 100.0 / count , buckets[i]);
      cli_print(cli, "%d total sessions open.", count);
      return CLI_OK;
}

int cmd_show_hist_open(struct cli_def *cli, char *command, char **argv, int argc)
{
      int s, i;
      int count = 0;
      int buckets[64];

      if (CLI_HELP_REQUESTED)
            return CLI_HELP_NO_ARGS;

      time(&time_now);
      for (i = 0; i < 64;++i) buckets[i] = 0;

      for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
      {
            int open = 0, d;
            if (!session[s].opened)
                  continue;

            d = time_now - session[s].opened;
            if (d < 0)
                  d = 0;
            while (d > 1 && open < 32)
            {
                  ++open;
                  d >>= 1; // half.
            }
            ++count;
            ++buckets[open];
      }

      s = 1;
      for (i = 0; i  < 30; ++i)
      {
            cli_print(cli, " < %8d seconds : %7.2f%% (%6d)", s, (double) buckets[i] * 100.0 / count , buckets[i]);
            s <<= 1;
      }
      cli_print(cli, "%d total sessions open.", count);
      return CLI_OK;
}

/* Unhide an avp.
 *
 * This unencodes the AVP using the L2TP secret and the previously
 * stored random vector.  It overwrites the hidden data with the
 * unhidden AVP subformat.
 */
static void unhide_value(uint8_t *value, size_t len, uint16_t type, uint8_t *vector, size_t vec_len)
{
      MD5_CTX ctx;
      uint8_t digest[16];
      uint8_t *last;
      size_t d = 0;
      uint16_t m = htons(type);

      // Compute initial pad
      MD5_Init(&ctx);
      MD5_Update(&ctx, (unsigned char *) &m, 2);
      MD5_Update(&ctx, config->l2tp_secret, strlen(config->l2tp_secret));
      MD5_Update(&ctx, vector, vec_len);
      MD5_Final(digest, &ctx);

      // pointer to last decoded 16 octets
      last = value;

      while (len > 0)
      {
            // calculate a new pad based on the last decoded block
            if (d >= sizeof(digest))
            {
                  MD5_Init(&ctx);
                  MD5_Update(&ctx, config->l2tp_secret, strlen(config->l2tp_secret));
                  MD5_Update(&ctx, last, sizeof(digest));
                  MD5_Final(digest, &ctx);

                  d = 0;
                  last = value;
            }

            *value++ ^= digest[d++];
            len--;
      }
}

int find_filter(char const *name, size_t len)
{
      int free = -1;
      int i;

      for (i = 0; i < MAXFILTER; i++)
      {
            if (!*ip_filters[i].name)
            {
                  if (free < 0)
                        free = i;

                  continue;
            }

            if (strlen(ip_filters[i].name) != len)
                  continue;

            if (!strncmp(ip_filters[i].name, name, len))
                  return i;
      }
                  
      return free;
}

static int ip_filter_port(ip_filter_portt *p, uint16_t port)
{
      switch (p->op)
      {
      case FILTER_PORT_OP_EQ:    return port == p->port;
      case FILTER_PORT_OP_NEQ:   return port != p->port;
      case FILTER_PORT_OP_GT:    return port > p->port;
      case FILTER_PORT_OP_LT:    return port < p->port;
      case FILTER_PORT_OP_RANGE: return port >= p->port && port <= p->port2;
      }

      return 0;
}

static int ip_filter_flag(uint8_t op, uint8_t sflags, uint8_t cflags, uint8_t flags)
{
      switch (op)
      {
      case FILTER_FLAG_OP_ANY:
            return (flags & sflags) || (~flags & cflags);

      case FILTER_FLAG_OP_ALL:
            return (flags & sflags) == sflags && (~flags & cflags) == cflags;

      case FILTER_FLAG_OP_EST:
            return (flags & (TCP_FLAG_ACK|TCP_FLAG_RST)) && (~flags & TCP_FLAG_SYN);
      }

      return 0;
}

int ip_filter(uint8_t *buf, int len, uint8_t filter)
{
      uint16_t frag_offset;
      uint8_t proto;
      in_addr_t src_ip;
      in_addr_t dst_ip;
      uint16_t src_port = 0;
      uint16_t dst_port = 0;
      uint8_t flags = 0;
      ip_filter_rulet *rule;

      if (len < 20) // up to end of destination address
            return 0;

      if ((*buf >> 4) != 4) // IPv4
            return 0;

      frag_offset = ntohs(*(uint16_t *) (buf + 6)) & 0x1fff;
      proto = buf[9];
      src_ip = *(in_addr_t *) (buf + 12);
      dst_ip = *(in_addr_t *) (buf + 16);

      if (frag_offset == 0 && (proto == IPPROTO_TCP || proto == IPPROTO_UDP))
      {
            int l = (buf[0] & 0xf) * 4; // length of IP header
            if (len < l + 4) // ports
                  return 0;

            src_port = ntohs(*(uint16_t *) (buf + l));
            dst_port = ntohs(*(uint16_t *) (buf + l + 2));
            if (proto == IPPROTO_TCP)
            {
                  if (len < l + 14) // flags
                        return 0;

                  flags = buf[l + 13] & 0x3f;
            }
      }

      for (rule = ip_filters[filter].rules; rule->action; rule++)
      {
            if (rule->proto != IPPROTO_IP && proto != rule->proto)
                  continue;

            if (rule->src_wild != INADDR_BROADCAST &&
                (src_ip & ~rule->src_wild) != (rule->src_ip & ~rule->src_wild))
                  continue;

            if (rule->dst_wild != INADDR_BROADCAST &&
                (dst_ip & ~rule->dst_wild) != (rule->dst_ip & ~rule->dst_wild))
                  continue;

            if (frag_offset)
            {
                  // layer 4 deny rules are skipped
                  if (rule->action == FILTER_ACTION_DENY &&
                      (rule->src_ports.op || rule->dst_ports.op || rule->tcp_flag_op))
                        continue;
            }
            else
            {
                  if (rule->frag)
                        continue;

                  if (proto == IPPROTO_TCP || proto == IPPROTO_UDP)
                  {
                        if (rule->src_ports.op && !ip_filter_port(&rule->src_ports, src_port))
                              continue;

                        if (rule->dst_ports.op && !ip_filter_port(&rule->dst_ports, dst_port))
                              continue;

                        if (proto == IPPROTO_TCP && rule->tcp_flag_op &&
                            !ip_filter_flag(rule->tcp_flag_op, rule->tcp_sflags, rule->tcp_cflags, flags))
                              continue;
                  }
            }

            // matched
            rule->counter++;
            return rule->action == FILTER_ACTION_PERMIT;
      }

      // default deny
      return 0;
}

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