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radius.c

// L2TPNS Radius Stuff

char const *cvs_id_radius = "$Id: radius.c,v 1.20 2004/12/16 08:49:53 bodea Exp $";

#include <time.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <malloc.h>
#include <string.h>
#include <fcntl.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <netinet/in.h>
#include "md5.h"
#include "constants.h"
#include "l2tpns.h"
#include "plugin.h"
#include "util.h"

extern radiust *radius;
extern sessiont *session;
extern tunnelt *tunnel;
extern configt *config;
extern int *radfds;
extern ip_filtert *ip_filters;

static const char *radius_state(int state)
{
      static char *tmp = NULL;
      int i;
      for (i = 0; radius_states[i]; i++)
            if (i == state) return radius_states[i];

      if (tmp == NULL) tmp = (char *)calloc(64, 1);
      sprintf(tmp, "%d", state);
      return tmp;
}

// Set up socket for radius requests
void initrad(void)
{
      int i;
      LOG(3, 0, 0, "Creating %d sockets for RADIUS queries\n", config->num_radfds);
      radfds = calloc(sizeof(int), config->num_radfds);
      for (i = 0; i < config->num_radfds; i++)
      {
            int flags;
            radfds[i] = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
            flags = fcntl(radfds[i], F_GETFL, 0);
            fcntl(radfds[i], F_SETFL, flags | O_NONBLOCK);
      }
}

void radiusclear(uint16_t r, sessionidt s)
{
      if (s) session[s].radius = 0;
      memset(&radius[r], 0, sizeof(radius[r])); // radius[r].state = RADIUSNULL;
}


static uint16_t get_free_radius()
{
      int count;
      static uint32_t next_radius_id = 0;

      for (count = MAXRADIUS; count > 0 ; --count)
      {
            ++next_radius_id;       // Find the next ID to check.
            if (next_radius_id >= MAXRADIUS)
                  next_radius_id = 1;

            if (radius[next_radius_id].state == RADIUSNULL)
            {
                  return next_radius_id;
            }
      }

      LOG(0, 0, 0, "Can't find a free radius session! This is very bad!\n");
      return 0;
}

uint16_t radiusnew(sessionidt s)
{
      uint16_t r = session[s].radius;

      /* re-use */
      if (r)
      {
            LOG(3, s, session[s].tunnel, "Re-used radius %d\n", r);
            return r;
      }

      if (!(r = get_free_radius()))
      {
            LOG(1, s, session[s].tunnel, "No free RADIUS sessions\n");
            STAT(radius_overflow);
            return 0;
      };

      memset(&radius[r], 0, sizeof(radius[r]));
      session[s].radius = r;
      radius[r].session = s;
      radius[r].state = RADIUSWAIT;
      radius[r].retry = TIME + 1200; // Wait at least 120 seconds to re-claim this.

      LOG(3, s, session[s].tunnel, "Allocated radius %d\n", r);
      return r;
}

// Send a RADIUS request
void radiussend(uint16_t r, uint8_t state)
{
      struct sockaddr_in addr;
      uint8_t b[4096];            // RADIUS packet
      char pass[129];
      int pl;
      uint8_t *p;
      sessionidt s;

      CSTAT(call_radiussend);

      s = radius[r].session;
      if (!config->numradiusservers)
      {
            LOG(0, s, session[s].tunnel, "No RADIUS servers\n");
            return;
      }
      if (!*config->radiussecret)
      {
            LOG(0, s, session[s].tunnel, "No RADIUS secret\n");
            return;
      }

      if (state != RADIUSAUTH && !config->radius_accounting)
      {
            // Radius accounting is turned off
            radiusclear(r, s);
            return;
      }

      if (radius[r].state != state)
            radius[r].try = 0;
      radius[r].state = state;
      radius[r].retry = backoff(radius[r].try++);
      LOG(4, s, session[s].tunnel, "Send RADIUS id %d sock %d state %s try %d\n",
            r >> RADIUS_SHIFT, r & RADIUS_MASK,
            radius_state(radius[r].state), radius[r].try);

      if (radius[r].try > config->numradiusservers * 2)
      {
            if (s)
            {
                  if (state == RADIUSAUTH)
                        sessionshutdown(s, "RADIUS timeout");
                  else
                  {
                        LOG(1, s, session[s].tunnel, "RADIUS timeout, but in state %s so don't timeout session\n",
                              radius_states[state]);
                        radiusclear(r, s);
                  }
                  STAT(radius_timeout);
            }
            else
            {
                  STAT(radius_retries);
                  radius[r].state = RADIUSWAIT;
                  radius[r].retry = 100;
            }
            return ;
      }
      // contruct RADIUS access request
      switch (state)
      {
            case RADIUSAUTH:
                  b[0] = 1;               // access request
                  break;
            case RADIUSSTART:
            case RADIUSSTOP:
                  b[0] = 4;               // accounting request
                  break;
            default:
                  LOG(0, 0, 0, "Unknown radius state %d\n", state);
      }
      b[1] = r >> RADIUS_SHIFT;       // identifier
      memcpy(b + 4, radius[r].auth, 16);
      p = b + 20;
      if (s)
      {
            *p = 1;                 // user name
            p[1] = strlen(session[s].user) + 2;
            strcpy(p + 2, session[s].user);
            p += p[1];
      }
      if (state == RADIUSAUTH)
      {
            if (radius[r].chap)
            {
                  *p = 3;            // CHAP password
                  p[1] = 19;         // length
                  p[2] = radius[r].id; // ID
                  memcpy(p + 3, radius[r].pass, 16); // response from CHAP request
                  p += p[1];
                  *p = 60;           // CHAP Challenge
                  p[1] = 18;         // length
                  memcpy(p + 2, radius[r].auth, 16);
                  p += p[1];
            }
            else
            {
                  strcpy(pass, radius[r].pass);
                  pl = strlen(pass);
                  while (pl & 15)
                        pass[pl++] = 0; // pad
                  if (pl)
                  {                // encrypt
                        hasht hash;
                        int p = 0;
                        while (p < pl)
                        {
                              MD5_CTX ctx;
                              MD5Init(&ctx);
                              MD5Update(&ctx, config->radiussecret, strlen(config->radiussecret));
                              if (p)
                                    MD5Update(&ctx, pass + p - 16, 16);
                              else
                                    MD5Update(&ctx, radius[r].auth, 16);
                              MD5Final(hash, &ctx);
                              do
                              {
                                    pass[p] ^= hash[p & 15];
                                    p++;
                              }
                              while (p & 15);
                        }
                  }
                  *p = 2;            // password
                  p[1] = pl + 2;
                  if (pl)
                        memcpy(p + 2, pass, pl);
                  p += p[1];
            }
      }
      else if (state == RADIUSSTART || state == RADIUSSTOP)
      {                          // accounting
            *p = 40;                // accounting type
            p[1] = 6;
            *(uint32_t *) (p + 2) = htonl((state == RADIUSSTART) ? 1 : 2);
            p += p[1];
            if (s)
            {
                  *p = 44;           // session ID
                  p[1] = 18;
                  sprintf(p + 2, "%08X%08X", session[s].id, session[s].opened);
                  p += p[1];
                  if (state == RADIUSSTOP)
                  {                // stop
                        *p = 42;      // input octets
                        p[1] = 6;
                        *(uint32_t *) (p + 2) = htonl(session[s].cin);
                        p += p[1];
                        *p = 43;      // output octets
                        p[1] = 6;
                        *(uint32_t *) (p + 2) = htonl(session[s].cout);
                        p += p[1];
                        *p = 46;      // session time
                        p[1] = 6;
                        *(uint32_t *) (p + 2) = htonl(time(NULL) - session[s].opened);
                        p += p[1];
                        *p = 47;      // input packets
                        p[1] = 6;
                        *(uint32_t *) (p + 2) = htonl(session[s].pin);
                        p += p[1];
                        *p = 48;      // output spackets
                        p[1] = 6;
                        *(uint32_t *) (p + 2) = htonl(session[s].pout);
                        p += p[1];
                  }
                  else
                  {                // start
                        *p = 41;      // delay
                        p[1] = 6;
                        *(uint32_t *) (p + 2) = htonl(time(NULL) - session[s].opened);
                        p += p[1];
                  }
            }
      }
      if (s)
      {
            *p = 5; // NAS-Port
            p[1] = 6;
            *(uint32_t *) (p + 2) = htonl(s);
            p += p[1];
      }
      if (s && session[s].ip)
      {
            *p = 8;                 // Framed-IP-Address
            p[1] = 6;
            *(uint32_t *) (p + 2) = htonl(session[s].ip);
            p += p[1];
      }
      if (*session[s].called)
      {
            *p = 30;                // called
            p[1] = strlen(session[s].called) + 2;
            strcpy(p + 2, session[s].called);
            p += p[1];
      }
      if (*radius[r].calling)
      {
            *p = 31;                // calling
            p[1] = strlen(radius[r].calling) + 2;
            strcpy(p + 2, radius[r].calling);
            p += p[1];
      }
      else if (*session[s].calling)
      {
            *p = 31;                // calling
            p[1] = strlen(session[s].calling) + 2;
            strcpy(p + 2, session[s].calling);
            p += p[1];
      }
      // NAS-IP-Address
      *p = 4;
      p[1] = 6;
      *(uint32_t *)(p + 2) = config->bind_address;
      p += p[1];

      // All AVpairs added
      *(uint16_t *) (b + 2) = htons(p - b);
      if (state != RADIUSAUTH)
      {
          // Build auth for accounting packet
          char z[16] = {0};
          char hash[16] = {0};
          MD5_CTX ctx;
          MD5Init(&ctx);
          MD5Update(&ctx, b, 4);
          MD5Update(&ctx, z, 16);
          MD5Update(&ctx, b + 20, (p - b) - 20);
          MD5Update(&ctx, config->radiussecret, strlen(config->radiussecret));
          MD5Final(hash, &ctx);
          memcpy(b + 4, hash, 16);
          memcpy(radius[r].auth, hash, 16);
      }
      memset(&addr, 0, sizeof(addr));
      addr.sin_family = AF_INET;
      *(uint32_t *) & addr.sin_addr = config->radiusserver[(radius[r].try - 1) % config->numradiusservers];
      {
            // get radius port
            uint16_t port = config->radiusport[(radius[r].try - 1) % config->numradiusservers];
            // no need to define the accounting port for itself:
            //  the accounting port is as far as I know always one more
            //  than the auth port    JK 20040713
            addr.sin_port = htons((state == RADIUSAUTH) ? port : port+1);
      }

      LOG_HEX(5, "RADIUS Send", b, (p - b));
      sendto(radfds[r & RADIUS_MASK], b, p - b, 0, (void *) &addr, sizeof(addr));
}

// process RADIUS response
void processrad(uint8_t *buf, int len, char socket_index)
{
      uint8_t b[MAXCONTROL];
      MD5_CTX ctx;
      uint16_t r;
      sessionidt s;
      tunnelidt t = 0;
      hasht hash;
      uint8_t routes = 0;

      int r_code, r_id ; // Radius code.

      r_code = buf[0]; // First byte in radius packet.
      r_id = buf[1]; // radius reply indentifier.


      CSTAT(call_processrad);

      LOG_HEX(5, "RADIUS Response", buf, len);
      if (len < 20 || len < ntohs(*(uint16_t *) (buf + 2)))
      {
            LOG(1, 0, 0, "Duff RADIUS response length %d\n", len);
            return ;
      }
      len = ntohs(*(uint16_t *) (buf + 2));
      r = socket_index | (r_id << RADIUS_SHIFT);
      s = radius[r].session;
      LOG(3, s, session[s].tunnel, "Received %s, radius %d response for session %u (code %d, id %d)\n",
                  radius_states[radius[r].state], r, s, r_code, r_id);
      if (!s && radius[r].state != RADIUSSTOP)
      {
            LOG(1, s, session[s].tunnel, "   Unexpected RADIUS response\n");
            return;
      }
      if (radius[r].state != RADIUSAUTH && radius[r].state != RADIUSSTART && radius[r].state != RADIUSSTOP)
      {
            LOG(1, s, session[s].tunnel, "   Unexpected RADIUS response\n");
            return;
      }
      t = session[s].tunnel;
      MD5Init(&ctx);
      MD5Update(&ctx, buf, 4);
      MD5Update(&ctx, radius[r].auth, 16);
      MD5Update(&ctx, buf + 20, len - 20);
      MD5Update(&ctx, config->radiussecret, strlen(config->radiussecret));
      MD5Final(hash, &ctx);
      do {
            if (memcmp(hash, buf + 4, 16))
            {
                  LOG(0, s, session[s].tunnel, "   Incorrect auth on RADIUS response!! (wrong secret in radius config?)\n");
                  return; // Do nothing. On timeout, it will try the next radius server.
            }
            if ((radius[r].state == RADIUSAUTH && *buf != 2 && *buf != 3) ||
                  ((radius[r].state == RADIUSSTART || radius[r].state == RADIUSSTOP) && *buf != 5))
            {
                  LOG(1, s, session[s].tunnel, "   Unexpected RADIUS response %d\n", *buf);
                  return; // We got something we didn't expect. Let the timeouts take
                        // care off finishing the radius session if that's really correct.
            }
            if (radius[r].state == RADIUSAUTH)
            {
                  LOG(4, s, session[s].tunnel, "   Original response is \"%s\"\n", (*buf == 2) ? "accept" : "reject");
                  // process auth response
                  if (radius[r].chap)
                  {
                        // CHAP
                        uint8_t *p = makeppp(b, sizeof(b), 0, 0, t, s, PPPCHAP);
                        if (!p) return;   // Abort!

                        {
                              struct param_post_auth packet = { &tunnel[t], &session[s], session[s].user, (*buf == 2), PPPCHAP };
                              run_plugins(PLUGIN_POST_AUTH, &packet);
                              *buf = packet.auth_allowed ? 2 : 3;
                        }

                        LOG(3, s, session[s].tunnel, "   CHAP User %s authentication %s.\n", session[s].user,
                                    (*buf == 2) ? "allowed" : "denied");
                        *p = (*buf == 2) ? 3 : 4;     // ack/nak
                        p[1] = radius[r].id;
                        *(uint16_t *) (p + 2) = ntohs(4); // no message
                        tunnelsend(b, (p - b) + 4, t); // send it
                  }
                  else
                  {
                        // PAP
                        uint8_t *p = makeppp(b, sizeof(b), 0, 0, t, s, PPPPAP);
                        if (!p) return;         // Abort!

                        {
                              struct param_post_auth packet = { &tunnel[t], &session[s], session[s].user, (*buf == 2), PPPPAP };
                              run_plugins(PLUGIN_POST_AUTH, &packet);
                              *buf = packet.auth_allowed ? 2 : 3;
                        }

                        LOG(3, s, session[s].tunnel, "   PAP User %s authentication %s.\n", session[s].user,
                                    (*buf == 2) ? "allowed" : "denied");
                        // ack/nak
                        *p = *buf;
                        p[1] = radius[r].id;
                        *(uint16_t *) (p + 2) = ntohs(5);
                        p[4] = 0; // no message
                        tunnelsend(b, (p - b) + 5, t); // send it
                  }

                  if (*buf == 2)
                  {
                        // Login successful
                        // Extract IP, routes, etc
                        uint8_t *p = buf + 20;
                        uint8_t *e = buf + len;
                        for (; p + 2 <= e && p[1] && p + p[1] <= e; p += p[1])
                        {
                              if (*p == 8)
                              {
                                    // Framed-IP-Address
                                    if (p[1] < 6) continue;
                                    session[s].ip = ntohl(*(uint32_t *) (p + 2));
                                    session[s].ip_pool_index = -1;
                                    LOG(3, s, session[s].tunnel, "   Radius reply contains IP address %s\n",
                                          fmtaddr(htonl(session[s].ip), 0));
                              }
                              else if (*p == 135)
                              {
                                    // DNS address
                                    if (p[1] < 6) continue;
                                    session[s].dns1 = ntohl(*(uint32_t *) (p + 2));
                                    LOG(3, s, session[s].tunnel, "   Radius reply contains primary DNS address %s\n",
                                          fmtaddr(htonl(session[s].dns1), 0));
                              }
                              else if (*p == 136)
                              {
                                    // DNS address
                                    if (p[1] < 6) continue;
                                    session[s].dns2 = ntohl(*(uint32_t *) (p + 2));
                                    LOG(3, s, session[s].tunnel, "   Radius reply contains secondary DNS address %s\n",
                                          fmtaddr(htonl(session[s].dns2), 0));
                              }
                              else if (*p == 22)
                              {
                                    // Framed-Route
                                    in_addr_t ip = 0, mask = 0;
                                    uint8_t u = 0;
                                    uint8_t bits = 0;
                                    uint8_t *n = p + 2;
                                    uint8_t *e = p + p[1];
                                    while (n < e && (isdigit(*n) || *n == '.'))
                                    {
                                          if (*n == '.')
                                          {
                                                ip = (ip << 8) + u;
                                                u = 0;
                                          }
                                          else
                                                u = u * 10 + *n - '0';
                                          n++;
                                    }
                                    ip = (ip << 8) + u;
                                    if (*n == '/')
                                    {
                                          n++;
                                          while (n < e && isdigit(*n))
                                                bits = bits * 10 + *n++ - '0';
                                          mask = (( -1) << (32 - bits));
                                    }
                                    else if ((ip >> 24) < 128)
                                          mask = 0xFF0000;
                                    else if ((ip >> 24) < 192)
                                          mask = 0xFFFF0000;
                                    else
                                          mask = 0xFFFFFF00;

                                    if (routes == MAXROUTE)
                                    {
                                          LOG(1, s, session[s].tunnel, "   Too many routes\n");
                                    }
                                    else if (ip)
                                    {
                                          LOG(3, s, session[s].tunnel, "   Radius reply contains route for %s/%s\n",
                                                fmtaddr(htonl(ip), 0), fmtaddr(htonl(mask), 1));
                                          
                                          session[s].route[routes].ip = ip;
                                          session[s].route[routes].mask = mask;
                                          routes++;
                                    }
                              }
                              else if (*p == 11)
                              {
                                    // Filter-Id
                                    char *filter = p + 2;
                                    int l = p[1] - 2;
                                    char *suffix;
                                    uint8_t *f = 0;
                                    int i;

                                    LOG(3, s, session[s].tunnel, "   Radius reply contains Filter-Id \"%.*s\"\n", l, filter);
                                    if ((suffix = memchr(filter, '.', l)))
                                    {
                                          int b = suffix - filter;
                                          if (l - b == 3 && !memcmp("in", suffix+1, 2))
                                                f = &session[s].filter_in;
                                          else if (l - b == 4 && !memcmp("out", suffix+1, 3))
                                                f = &session[s].filter_out;

                                          l = b;
                                    }

                                    if (!f)
                                    {
                                          LOG(3, s, session[s].tunnel, "    Invalid filter\n");
                                          continue;
                                    }

                                    for (*f = 0, i = 0; !*f && i < MAXFILTER; i++)
                                          if (strlen(ip_filters[i].name) == l &&
                                              !strncmp(ip_filters[i].name, filter, l))
                                                *f = i + 1;

                                    if (*f)
                                          ip_filters[*f - 1].used++;
                                    else
                                          LOG(3, s, session[s].tunnel, "    Unknown filter\n");

                              }
                              else if (*p == 26 && p[1] >= 7)
                              {
                                    // Vendor-Specific Attribute
                                    int vendor = ntohl(*(int *)(p + 2));
                                    char attrib = *(p + 6);
                                    char attrib_length = *(p + 7) - 2;
                                    char *avpair, *value, *key, *newp;

                                    LOG(3, s, session[s].tunnel, "   Radius reply contains Vendor-Specific.  Vendor=%d Attrib=%d Length=%d\n", vendor, attrib, attrib_length);
                                    if (vendor != 9 || attrib != 1)
                                    {
                                          LOG(3, s, session[s].tunnel, "      Unknown vendor-specific\n");
                                          continue;
                                    }

                                    if (attrib_length < 0) continue;

                                    avpair = key = calloc(attrib_length + 1, 1);
                                    memcpy(avpair, p + 8, attrib_length);
                                    LOG(3, s, session[s].tunnel, "      Cisco-Avpair value: %s\n", avpair);
                                    do {
                                          value = strchr(key, '=');
                                          if (!value) break;
                                          *value++ = 0;

                                          // Trim quotes off reply string
                                          if (*value == '\'' || *value == '\"')
                                          {
                                                char *x;
                                                value++;
                                                x = value + strlen(value) - 1;
                                                if (*x == '\'' || *x == '\"')
                                                      *x = 0;
                                          }

                                          // Run hooks
                                          newp = strchr(value, ',');
                                          if (newp) *newp++ = 0;
                                          {
                                                struct param_radius_response p = { &tunnel[session[s].tunnel], &session[s], key, value };
                                                run_plugins(PLUGIN_RADIUS_RESPONSE, &p);
                                          }
                                          key = newp;
                                    } while (newp);
                                    free(avpair);
                              }
                        }
                  }
                  else if (*buf == 3)
                  {
                        LOG(2, s, session[s].tunnel, "   Authentication denied for %s\n", session[s].user);
//FIXME: We should tear down the session here!
                        break;
                  }

                  if (!session[s].dns1 && config->default_dns1)
                  {
                        session[s].dns1 = htonl(config->default_dns1);
                        LOG(3, s, t, "   Sending dns1 = %s\n", fmtaddr(config->default_dns1, 0));
                  }
                  if (!session[s].dns2 && config->default_dns2)
                  {
                        session[s].dns2 = htonl(config->default_dns2);
                        LOG(3, s, t, "   Sending dns2 = %s\n", fmtaddr(config->default_dns2, 0));
                  }

                  // Valid Session, set it up
                  session[s].unique_id = 0;
                  sessionsetup(t, s);
            }
            else
            {
                        // An ack for a stop or start record.
                  LOG(3, s, t, "   RADIUS accounting ack recv in state %s\n", radius_states[radius[r].state]);
                  break;
            }
      } while (0);

      // finished with RADIUS
      radiusclear(r, s);
}

// Send a retry for RADIUS/CHAP message
void radiusretry(uint16_t r)
{
      sessionidt s = radius[r].session;
      tunnelidt t = 0;

      CSTAT(call_radiusretry);

      if (s)
            t = session[s].tunnel;
      radius[r].retry = backoff(radius[r].try + 1);
      switch (radius[r].state)
      {
            case RADIUSCHAP:           // sending CHAP down PPP
                  sendchap(t, s);
                  break;
            case RADIUSIPCP:
                  sendipcp(t, s);         // send IPCP
                  break;
            case RADIUSAUTH:           // sending auth to RADIUS server
                  radiussend(r, RADIUSAUTH);
                  break;
            case RADIUSSTART:          // sending start accounting to RADIUS server
                  radiussend(r, RADIUSSTART);
                  break;
            case RADIUSSTOP:           // sending stop accounting to RADIUS server
                  radiussend(r, RADIUSSTOP);
                  break;
            default:
            case RADIUSNULL:           // Not in use
            case RADIUSWAIT:           // waiting timeout before available, in case delayed reply from RADIUS server
                  // free up RADIUS task
                  radiusclear(r, s);
                  LOG(3, s, session[s].tunnel, "Freeing up radius session %d\n", r);
                  break;
      }
}

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