ppp.c

   1 // L2TPNS PPP Stuff
   2
   3 char const *cvs_id_ppp = "$Id: ppp.c,v 1.99 2006/04/18 06:00:08 bodea Exp $";
   4
   5 #include <stdio.h>
   6 #include <string.h>
   7 #include <unistd.h>
   8 #include <errno.h>
   9 #include <stdlib.h>
  10 #include "l2tpns.h"
  11 #include "constants.h"
  12 #include "plugin.h"
  13 #include "util.h"
  14 #include "tbf.h"
  15 #include "cluster.h"
  16
  17 extern tunnelt *tunnel;
  18 extern sessiont *session;
  19 extern radiust *radius;
  20 extern int tunfd;
  21 extern char hostname[];
  22 extern uint32_t eth_tx;
  23 extern time_t time_now;
  24 extern configt *config;
  25
  26 static int add_lcp_auth(uint8_t *b, int size, int authtype);
  27
  28 // Process PAP messages
  29 void processpap(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
  30 {
  31         char user[MAXUSER];
  32         char pass[MAXPASS];
  33         uint16_t hl;
  34         uint16_t r;
  35
  36         CSTAT(processpap);
  37
  38         LOG_HEX(5, "PAP", p, l);
  39         if (l < 4)
  40         {
  41                 LOG(1, s, t, "Short PAP %u bytes\n", l);
  42                 STAT(tunnel_rx_errors);
  43                 sessionshutdown(s, "Short PAP packet.", CDN_ADMIN_DISC, TERM_USER_ERROR);
  44                 return;
  45         }
  46
  47         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
  48         {
  49                 LOG(1, s, t, "Length mismatch PAP %u/%u\n", hl, l);
  50                 STAT(tunnel_rx_errors);
  51                 sessionshutdown(s, "PAP length mismatch.", CDN_ADMIN_DISC, TERM_USER_ERROR);
  52                 return;
  53         }
  54         l = hl;
  55
  56         if (*p != 1)
  57         {
  58                 LOG(1, s, t, "Unexpected PAP code %d\n", *p);
  59                 STAT(tunnel_rx_errors);
  60                 sessionshutdown(s, "Unexpected PAP code.", CDN_ADMIN_DISC, TERM_USER_ERROR);
  61                 return;
  62         }
  63
  64         if (session[s].ppp.phase != Authenticate)
  65         {
  66                 LOG(2, s, t, "PAP ignored in %s phase\n", ppp_phase(session[s].ppp.phase));
  67                 return;
  68         }
  69
  70         {
  71                 uint8_t *b = p;
  72                 b += 4;
  73                 user[0] = pass[0] = 0;
  74                 if (*b && *b < sizeof(user))
  75                 {
  76                         memcpy(user, b + 1, *b);
  77                         user[*b] = 0;
  78                         b += 1 + *b;
  79                         if (*b && *b < sizeof(pass))
  80                         {
  81                                 memcpy(pass, b + 1, *b);
  82                                 pass[*b] = 0;
  83                         }
  84                 }
  85                 LOG(3, s, t, "PAP login %s/%s\n", user, pass);
  86         }
  87
  88         if (session[s].ip || !(r = radiusnew(s)))
  89         {
  90                 // respond now, either no RADIUS available or already authenticated
  91                 uint8_t b[MAXETHER];
  92                 uint8_t id = p[1];
  93                 uint8_t *p = makeppp(b, sizeof(b), 0, 0, s, t, PPPPAP);
  94                 if (!p) return;
  95
  96                 if (session[s].ip)
  97                         *p = 2;                         // ACK
  98                 else
  99                         *p = 3;                         // cant authorise
 100                 p[1] = id;
 101                 *(uint16_t *) (p + 2) = htons(5);       // length
 102                 p[4] = 0;                               // no message
 103                 tunnelsend(b, 5 + (p - b), t);          // send it
 104
 105                 if (session[s].ip)
 106                 {
 107                         LOG(3, s, t, "Already an IP allocated: %s (%d)\n",
 108                                 fmtaddr(htonl(session[s].ip), 0), session[s].ip_pool_index);
 109                 }
 110                 else
 111                 {
 112                         LOG(1, s, t, "No RADIUS session available to authenticate session...\n");
 113                         sessionshutdown(s, "No free RADIUS sessions.", CDN_UNAVAILABLE, TERM_SERVICE_UNAVAILABLE);
 114                 }
 115         }
 116         else
 117         {
 118                 // Run PRE_AUTH plugins
 119                 struct param_pre_auth packet = { &tunnel[t], &session[s], strdup(user), strdup(pass), PPPPAP, 1 };
 120                 run_plugins(PLUGIN_PRE_AUTH, &packet);
 121                 if (!packet.continue_auth)
 122                 {
 123                         LOG(3, s, t, "A plugin rejected PRE_AUTH\n");
 124                         if (packet.username) free(packet.username);
 125                         if (packet.password) free(packet.password);
 126                         return;
 127                 }
 128
 129                 strncpy(session[s].user, packet.username, sizeof(session[s].user) - 1);
 130                 strncpy(radius[r].pass, packet.password, sizeof(radius[r].pass) - 1);
 131
 132                 free(packet.username);
 133                 free(packet.password);
 134
 135                 radius[r].id = p[1];
 136                 LOG(3, s, t, "Sending login for %s/%s to RADIUS\n", user, pass);
 137                 radiussend(r, RADIUSAUTH);
 138         }
 139 }
 140
 141 // Process CHAP messages
 142 void processchap(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 143 {
 144         uint16_t r;
 145         uint16_t hl;
 146
 147         CSTAT(processchap);
 148
 149         LOG_HEX(5, "CHAP", p, l);
 150
 151         if (l < 4)
 152         {
 153                 LOG(1, s, t, "Short CHAP %u bytes\n", l);
 154                 STAT(tunnel_rx_errors);
 155                 sessionshutdown(s, "Short CHAP packet.", CDN_ADMIN_DISC, TERM_USER_ERROR);
 156                 return;
 157         }
 158
 159         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
 160         {
 161                 LOG(1, s, t, "Length mismatch CHAP %u/%u\n", hl, l);
 162                 STAT(tunnel_rx_errors);
 163                 sessionshutdown(s, "CHAP length mismatch.", CDN_ADMIN_DISC, TERM_USER_ERROR);
 164                 return;
 165         }
 166         l = hl;
 167
 168         if (*p != 2)
 169         {
 170                 LOG(1, s, t, "Unexpected CHAP response code %d\n", *p);
 171                 STAT(tunnel_rx_errors);
 172                 sessionshutdown(s, "CHAP length mismatch.", CDN_ADMIN_DISC, TERM_USER_ERROR);
 173                 return;
 174         }
 175
 176         r = sess_local[s].radius;
 177         if (!r)
 178         {
 179                 LOG(3, s, t, "Unexpected CHAP message\n");
 180                 return;
 181         }
 182
 183         if (session[s].ppp.phase != Authenticate)
 184         {
 185                 LOG(2, s, t, "CHAP ignored in %s phase\n", ppp_phase(session[s].ppp.phase));
 186                 return;
 187         }
 188
 189         if (p[1] != radius[r].id)
 190         {
 191                 LOG(1, s, t, "Wrong CHAP response ID %d (should be %d) (%d)\n", p[1], radius[r].id, r);
 192                 STAT(tunnel_rx_errors);
 193                 sessionshutdown(s, "Unexpected CHAP response ID.", CDN_ADMIN_DISC, TERM_USER_ERROR);
 194                 return;
 195         }
 196
 197         if (l < 5 || p[4] != 16)
 198         {
 199                 LOG(1, s, t, "Bad CHAP response length %d\n", l < 5 ? -1 : p[4]);
 200                 STAT(tunnel_rx_errors);
 201                 sessionshutdown(s, "Bad CHAP response length.", CDN_ADMIN_DISC, TERM_USER_ERROR);
 202                 return;
 203         }
 204
 205         l -= 5;
 206         p += 5;
 207         if (l < 16 || l - 16 >= sizeof(session[s].user))
 208         {
 209                 LOG(1, s, t, "CHAP user too long %d\n", l - 16);
 210                 STAT(tunnel_rx_errors);
 211                 sessionshutdown(s, "CHAP username too long.", CDN_ADMIN_DISC, TERM_USER_ERROR);
 212                 return;
 213         }
 214
 215         // Run PRE_AUTH plugins
 216         {
 217                 struct param_pre_auth packet = { &tunnel[t], &session[s], NULL, NULL, PPPCHAP, 1 };
 218
 219                 packet.password = calloc(17, 1);
 220                 memcpy(packet.password, p, 16);
 221
 222                 p += 16;
 223                 l -= 16;
 224
 225                 packet.username = calloc(l + 1, 1);
 226                 memcpy(packet.username, p, l);
 227
 228                 run_plugins(PLUGIN_PRE_AUTH, &packet);
 229                 if (!packet.continue_auth)
 230                 {
 231                         LOG(3, s, t, "A plugin rejected PRE_AUTH\n");
 232                         if (packet.username) free(packet.username);
 233                         if (packet.password) free(packet.password);
 234                         return;
 235                 }
 236
 237                 strncpy(session[s].user, packet.username, sizeof(session[s].user) - 1);
 238                 memcpy(radius[r].pass, packet.password, 16);
 239
 240                 free(packet.username);
 241                 free(packet.password);
 242         }
 243
 244         radius[r].chap = 1;
 245         LOG(3, s, t, "CHAP login %s\n", session[s].user);
 246         radiussend(r, RADIUSAUTH);
 247 }
 248
 249 static void dumplcp(uint8_t *p, int l)
 250 {
 251         int x = l - 4;
 252         uint8_t *o = (p + 4);
 253
 254         LOG_HEX(5, "PPP LCP Packet", p, l);
 255         LOG(4, 0, 0, "PPP LCP Packet type %d (%s len %d)\n", *p, ppp_code((int)*p), ntohs( ((uint16_t *) p)[1]) );
 256         LOG(4, 0, 0, "Length: %d\n", l);
 257         if (*p != ConfigReq && *p != ConfigRej && *p != ConfigAck)
 258                 return;
 259
 260         while (x > 2)
 261         {
 262                 int type = o[0];
 263                 int length = o[1];
 264                 if (length < 2)
 265                 {
 266                         LOG(4, 0, 0, "  Option length is %d...\n", length);
 267                         break;
 268                 }
 269                 if (type == 0)
 270                 {
 271                         LOG(4, 0, 0, "  Option type is 0...\n");
 272                         x -= length;
 273                         o += length;
 274                         continue;
 275                 }
 276                 switch (type)
 277                 {
 278                         case 1: // Maximum-Receive-Unit
 279                                 if (length == 4)
 280                                         LOG(4, 0, 0, "    %s %d\n", ppp_lcp_option(type), ntohs(*(uint16_t *)(o + 2)));
 281                                 else
 282                                         LOG(4, 0, 0, "    %s odd length %d\n", ppp_lcp_option(type), length);
 283                                 break;
 284                         case 2: // Async-Control-Character-Map
 285                                 if (length == 6)
 286                                 {
 287                                         uint32_t asyncmap = ntohl(*(uint32_t *)(o + 2));
 288                                         LOG(4, 0, 0, "    %s %x\n", ppp_lcp_option(type), asyncmap);
 289                                 }
 290                                 else
 291                                         LOG(4, 0, 0, "    %s odd length %d\n", ppp_lcp_option(type), length);
 292                                 break;
 293                         case 3: // Authentication-Protocol
 294                                 if (length == 4)
 295                                 {
 296                                         int proto = ntohs(*(uint16_t *)(o + 2));
 297                                         LOG(4, 0, 0, "    %s 0x%x (%s)\n", ppp_lcp_option(type), proto,
 298                                                 proto == PPPPAP  ? "PAP"  : "UNSUPPORTED");
 299                                 }
 300                                 else if (length == 5)
 301                                 {
 302                                         int proto = ntohs(*(uint16_t *)(o + 2));
 303                                         int algo = *(o + 4);
 304                                         LOG(4, 0, 0, "    %s 0x%x 0x%x (%s)\n", ppp_lcp_option(type), proto, algo,
 305                                                 (proto == PPPCHAP && algo == 5) ? "CHAP MD5"  : "UNSUPPORTED");
 306                                 }
 307                                 else
 308                                         LOG(4, 0, 0, "    %s odd length %d\n", ppp_lcp_option(type), length);
 309                                 break;
 310                         case 4: // Quality-Protocol
 311                                 {
 312                                         uint32_t qp = ntohl(*(uint32_t *)(o + 2));
 313                                         LOG(4, 0, 0, "    %s %x\n", ppp_lcp_option(type), qp);
 314                                 }
 315                                 break;
 316                         case 5: // Magic-Number
 317                                 if (length == 6)
 318                                 {
 319                                         uint32_t magicno = ntohl(*(uint32_t *)(o + 2));
 320                                         LOG(4, 0, 0, "    %s %x\n", ppp_lcp_option(type), magicno);
 321                                 }
 322                                 else
 323                                         LOG(4, 0, 0, "    %s odd length %d\n", ppp_lcp_option(type), length);
 324                                 break;
 325                         case 7: // Protocol-Field-Compression
 326                         case 8: // Address-And-Control-Field-Compression
 327                                 LOG(4, 0, 0, "    %s\n", ppp_lcp_option(type));
 328                                 break;
 329                         default:
 330                                 LOG(2, 0, 0, "    Unknown PPP LCP Option type %d\n", type);
 331                                 break;
 332                 }
 333                 x -= length;
 334                 o += length;
 335         }
 336 }
 337
 338 void lcp_open(sessionidt s, tunnelidt t)
 339 {
 340         // transition to Authentication or Network phase:
 341         session[s].ppp.phase = sess_local[s].lcp_authtype ? Authenticate : Network;
 342
 343         LOG(3, s, t, "LCP: Opened, phase %s\n", ppp_phase(session[s].ppp.phase));
 344
 345         // LCP now Opened
 346         change_state(s, lcp, Opened);
 347
 348         if (session[s].ppp.phase == Authenticate)
 349         {
 350                 if (sess_local[s].lcp_authtype == AUTHCHAP)
 351                         sendchap(s, t);
 352         }
 353         else
 354         {
 355                 // This-Layer-Up
 356                 sendipcp(s, t);
 357                 change_state(s, ipcp, RequestSent);
 358                 // move to passive state for IPv6 (if configured), CCP
 359                 if (config->ipv6_prefix.s6_addr[0])
 360                         change_state(s, ipv6cp, Stopped);
 361                 else
 362                         change_state(s, ipv6cp, Closed);
 363
 364                 change_state(s, ccp, Stopped);
 365         }
 366 }
 367
 368 static void lcp_restart(sessionidt s)
 369 {
 370         session[s].ppp.phase = Establish;
 371         // This-Layer-Down
 372         change_state(s, ipcp, Dead);
 373         change_state(s, ipv6cp, Dead);
 374         change_state(s, ccp, Dead);
 375 }
 376
 377 static uint8_t *ppp_conf_rej(sessionidt s, uint8_t *buf, size_t blen, uint16_t mtype,
 378         uint8_t **response, uint8_t *queued, uint8_t *packet, uint8_t *option)
 379 {
 380         if (!*response || **response != ConfigRej)
 381         {
 382                 queued = *response = makeppp(buf, blen, packet, 2, s, session[s].tunnel, mtype);
 383                 if (!queued)
 384                         return 0;
 385
 386                 *queued = ConfigRej;
 387                 queued += 4;
 388         }
 389
 390         if ((queued - buf + option[1]) > blen)
 391         {
 392                 LOG(2, s, session[s].tunnel, "PPP overflow for ConfigRej (proto %u, option %u).\n", mtype, *option);
 393                 return 0;
 394         }
 395
 396         memcpy(queued, option, option[1]);
 397         return queued + option[1];
 398 }
 399
 400 static uint8_t *ppp_conf_nak(sessionidt s, uint8_t *buf, size_t blen, uint16_t mtype,
 401         uint8_t **response, uint8_t *queued, uint8_t *packet, uint8_t *option,
 402         uint8_t *value, size_t vlen)
 403 {
 404         int *nak_sent;
 405         switch (mtype)
 406         {
 407         case PPPLCP:    nak_sent = &sess_local[s].lcp.nak_sent;    break;
 408         case PPPIPCP:   nak_sent = &sess_local[s].ipcp.nak_sent;   break;
 409         case PPPIPV6CP: nak_sent = &sess_local[s].ipv6cp.nak_sent; break;
 410         default:        return 0; // ?
 411         }
 412
 413         if (*response && **response != ConfigNak)
 414         {
 415                 if (*nak_sent < config->ppp_max_failure) // reject queued
 416                         return queued;
 417
 418                 return ppp_conf_rej(s, buf, blen, mtype, response, 0, packet, option);
 419         }
 420
 421         if (!*response)
 422         {
 423                 if (*nak_sent >= config->ppp_max_failure)
 424                         return ppp_conf_rej(s, buf, blen, mtype, response, 0, packet, option);
 425
 426                 queued = *response = makeppp(buf, blen, packet, 2, s, session[s].tunnel, mtype);
 427                 if (!queued)
 428                         return 0;
 429
 430                 (*nak_sent)++;
 431                 *queued = ConfigNak;
 432                 queued += 4;
 433         }
 434
 435         if ((queued - buf + vlen + 2) > blen)
 436         {
 437                 LOG(2, s, session[s].tunnel, "PPP overflow for ConfigNak (proto %u, option %u).\n", mtype, *option);
 438                 return 0;
 439         }
 440
 441         *queued++ = *option;
 442         *queued++ = vlen + 2;
 443         memcpy(queued, value, vlen);
 444         return queued + vlen;
 445 }
 446
 447 static void ppp_code_rej(sessionidt s, tunnelidt t, uint16_t proto,
 448         char *pname, uint8_t *p, uint16_t l, uint8_t *buf, size_t size)
 449 {
 450         uint8_t *q;
 451         int mru = session[s].mru;
 452         if (mru < MINMTU) mru = MINMTU;
 453         if (mru > size) mru = size;
 454
 455         l += 4;
 456         if (l > mru) l = mru;
 457
 458         q = makeppp(buf, size, 0, 0, s, t, proto);
 459         if (!q) return;
 460
 461         *q = CodeRej;
 462         *(q + 1) = ++sess_local[s].lcp_ident;
 463         *(uint16_t *)(q + 2) = htons(l);
 464         memcpy(q + 4, p, l - 4);
 465
 466         LOG(2, s, t, "Unexpected %s code %s\n", pname, ppp_code(*p));
 467         LOG(3, s, t, "%s: send %s\n", pname, ppp_code(*q));
 468         if (config->debug > 3) dumplcp(q, l);
 469
 470         tunnelsend(buf, l + (q - buf), t);
 471 }
 472
 473 // Process LCP messages
 474 void processlcp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 475 {
 476         uint8_t b[MAXETHER];
 477         uint8_t *q = NULL;
 478         uint16_t hl;
 479
 480         CSTAT(processlcp);
 481
 482         LOG_HEX(5, "LCP", p, l);
 483         if (l < 4)
 484         {
 485                 LOG(1, s, t, "Short LCP %d bytes\n", l);
 486                 STAT(tunnel_rx_errors);
 487                 return ;
 488         }
 489
 490         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
 491         {
 492                 LOG(1, s, t, "Length mismatch LCP %u/%u\n", hl, l);
 493                 STAT(tunnel_rx_errors);
 494                 return ;
 495         }
 496         l = hl;
 497
 498         if (session[s].die) // going down...
 499                 return;
 500
 501         LOG((*p == EchoReq || *p == EchoReply) ? 4 : 3, s, t,
 502                 "LCP: recv %s\n", ppp_code(*p));
 503
 504         if (config->debug > 3) dumplcp(p, l);
 505
 506         if (*p == ConfigAck)
 507         {
 508                 int x = l - 4;
 509                 uint8_t *o = (p + 4);
 510                 int authtype = 0;
 511
 512                 while (x > 2)
 513                 {
 514                         int type = o[0];
 515                         int length = o[1];
 516
 517                         if (length == 0 || type == 0 || x < length) break;
 518                         switch (type)
 519                         {
 520                                 case 3: // Authentication-Protocol
 521                                         {
 522                                                 int proto = ntohs(*(uint16_t *)(o + 2));
 523                                                 if (proto == PPPPAP)
 524                                                         authtype = AUTHPAP;
 525                                                 else if (proto == PPPCHAP && *(o + 4) == 5)
 526                                                         authtype = AUTHCHAP;
 527                                         }
 528
 529                                         break;
 530                         }
 531                         x -= length;
 532                         o += length;
 533                 }
 534
 535                 if (!session[s].ip && authtype)
 536                         sess_local[s].lcp_authtype = authtype;
 537
 538                 switch (session[s].ppp.lcp)
 539                 {
 540                 case RequestSent:
 541                         initialise_restart_count(s, lcp);
 542                         change_state(s, lcp, AckReceived);
 543                         break;
 544
 545                 case AckReceived:
 546                 case Opened:
 547                         LOG(2, s, t, "LCP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.lcp));
 548                         if (session[s].ppp.lcp == Opened)
 549                                 lcp_restart(s);
 550
 551                         sendlcp(s, t);
 552                         change_state(s, lcp, RequestSent);
 553                         break;
 554
 555                 case AckSent:
 556                         lcp_open(s, t);
 557                         break;
 558
 559                 default:
 560                         LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp));
 561                 }
 562         }
 563         else if (*p == ConfigReq)
 564         {
 565                 int x = l - 4;
 566                 uint8_t *o = (p + 4);
 567                 uint8_t *response = 0;
 568                 static uint8_t asyncmap[4] = { 0, 0, 0, 0 }; // all zero
 569                 static uint8_t authproto[5];
 570
 571                 while (x > 2)
 572                 {
 573                         int type = o[0];
 574                         int length = o[1];
 575
 576                         if (length == 0 || type == 0 || x < length) break;
 577                         switch (type)
 578                         {
 579                                 case 1: // Maximum-Receive-Unit
 580                                         {
 581                                                 uint16_t mru = ntohs(*(uint16_t *)(o + 2));
 582                                                 if (mru >= MINMTU)
 583                                                 {
 584                                                         session[s].mru = mru;
 585                                                         cluster_send_session(s);
 586                                                         break;
 587                                                 }
 588
 589                                                 LOG(3, s, t, "    Remote requesting MRU of %u.  Rejecting.\n", mru);
 590                                                 mru = htons(MRU);
 591                                                 q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, (uint8_t *) &mru, sizeof(mru));
 592                                         }
 593                                         break;
 594
 595                                 case 2: // Async-Control-Character-Map
 596                                         if (!ntohl(*(uint32_t *)(o + 2))) // all bits zero is OK
 597                                                 break;
 598
 599                                         LOG(3, s, t, "    Remote requesting asyncmap.  Rejecting.\n");
 600                                         q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, asyncmap, sizeof(asyncmap));
 601                                         break;
 602
 603                                 case 3: // Authentication-Protocol
 604                                         {
 605                                                 int proto = ntohs(*(uint16_t *)(o + 2));
 606                                                 char proto_name[] = "0x0000";
 607                                                 int alen;
 608
 609                                                 if (proto == PPPPAP)
 610                                                 {
 611                                                         if (config->radius_authtypes & AUTHPAP)
 612                                                         {
 613                                                                 sess_local[s].lcp_authtype = AUTHPAP;
 614                                                                 break;
 615                                                         }
 616
 617                                                         strcpy(proto_name, "PAP");
 618                                                 }
 619                                                 else if (proto == PPPCHAP)
 620                                                 {
 621                                                         if (config->radius_authtypes & AUTHCHAP
 622                                                             && *(o + 4) == 5) // MD5
 623                                                         {
 624                                                                 sess_local[s].lcp_authtype = AUTHCHAP;
 625                                                                 break;
 626                                                         }
 627
 628                                                         strcpy(proto_name, "CHAP");
 629                                                 }
 630                                                 else
 631                                                         sprintf(proto_name, "%#4.4x", proto);
 632
 633                                                 LOG(3, s, t, "    Remote requesting %s authentication.  Rejecting.\n", proto_name);
 634
 635                                                 alen = add_lcp_auth(authproto, sizeof(authproto), config->radius_authprefer);
 636                                                 if (alen < 2) break; // paranoia
 637
 638                                                 q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, authproto + 2, alen - 2);
 639                                                 if (q && *response == ConfigNak &&
 640                                                         config->radius_authtypes != config->radius_authprefer)
 641                                                 {
 642                                                         // alternate type
 643                                                         alen = add_lcp_auth(authproto, sizeof(authproto), config->radius_authtypes & ~config->radius_authprefer);
 644                                                         if (alen < 2) break;
 645                                                         q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, authproto + 2, alen - 2);
 646                                                 }
 647
 648                                                 break;
 649                                         }
 650                                         break;
 651
 652                                 case 4: // Quality-Protocol
 653                                 case 5: // Magic-Number
 654                                 case 7: // Protocol-Field-Compression
 655                                 case 8: // Address-And-Control-Field-Compression
 656                                         break;
 657
 658                                 default: // Reject any unknown options
 659                                         LOG(3, s, t, "    Rejecting unknown PPP LCP option %d\n", type);
 660                                         q = ppp_conf_rej(s, b, sizeof(b), PPPLCP, &response, q, p, o);
 661                         }
 662                         x -= length;
 663                         o += length;
 664                 }
 665
 666                 if (response)
 667                 {
 668                         l = q - response; // LCP packet length
 669                         *((uint16_t *) (response + 2)) = htons(l); // update header
 670                 }
 671                 else
 672                 {
 673                         // Send packet back as ConfigAck
 674                         response = makeppp(b, sizeof(b), p, l, s, t, PPPLCP);
 675                         if (!response) return;
 676                         *response = ConfigAck;
 677                 }
 678
 679                 switch (session[s].ppp.lcp)
 680                 {
 681                 case Closed:
 682                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPLCP);
 683                         if (!response) return;
 684                         *response = TerminateAck;
 685                         *((uint16_t *) (response + 2)) = htons(l = 4);
 686                         break;
 687
 688                 case Stopped:
 689                         initialise_restart_count(s, lcp);
 690                         sendlcp(s, t);
 691                         if (*response == ConfigAck)
 692                                 change_state(s, lcp, AckSent);
 693                         else
 694                                 change_state(s, lcp, RequestSent);
 695
 696                         break;
 697
 698                 case RequestSent:
 699                         if (*response == ConfigAck)
 700                                 change_state(s, lcp, AckSent);
 701
 702                         break;
 703
 704                 case AckReceived:
 705                         if (*response == ConfigAck)
 706                                 lcp_open(s, t);
 707
 708                         break;
 709
 710                 case Opened:
 711                         lcp_restart(s);
 712                         sendlcp(s, t);
 713                         /* fallthrough */
 714
 715                 case AckSent:
 716                         if (*response == ConfigAck)
 717                                 change_state(s, lcp, AckSent);
 718                         else
 719                                 change_state(s, lcp, RequestSent);
 720
 721                         break;
 722
 723                 default:
 724                         LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp));
 725                         return;
 726                 }
 727
 728                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*response));
 729                 if (config->debug > 3) dumplcp(response, l);
 730
 731                 tunnelsend(b, l + (response - b), t);
 732         }
 733         else if (*p == ConfigNak || *p == ConfigRej)
 734         {
 735                 int x = l - 4;
 736                 uint8_t *o = (p + 4);
 737                 int authtype = -1;
 738
 739                 while (x > 2)
 740                 {
 741                         int type = o[0];
 742                         int length = o[1];
 743
 744                         if (length == 0 || type == 0 || x < length) break;
 745                         switch (type)
 746                         {
 747                                 case 1: // Maximum-Receive-Unit
 748                                         if (*p == ConfigNak)
 749                                         {
 750                                                 if (length < 4) break;
 751                                                 sess_local[s].ppp_mru = ntohs(*(uint16_t *)(o + 2));
 752                                                 LOG(3, s, t, "    Remote requested MRU of %u\n", sess_local[s].ppp_mru);
 753                                         }
 754                                         else
 755                                         {
 756                                                 sess_local[s].ppp_mru = 0;
 757                                                 LOG(3, s, t, "    Remote rejected MRU negotiation\n");
 758                                         }
 759
 760                                         break;
 761
 762                                 case 3: // Authentication-Protocol
 763                                         if (authtype > 0)
 764                                                 break;
 765
 766                                         if (*p == ConfigNak)
 767                                         {
 768                                                 int proto;
 769
 770                                                 if (length < 4) break;
 771                                                 proto = ntohs(*(uint16_t *)(o + 2));
 772
 773                                                 if (proto == PPPPAP)
 774                                                 {
 775                                                         authtype = config->radius_authtypes & AUTHPAP;
 776                                                         LOG(3, s, t, "    Remote requested PAP authentication...%sing\n",
 777                                                                 authtype ? "accept" : "reject");
 778                                                 }
 779                                                 else if (proto == PPPCHAP && length > 4 && *(o + 4) == 5)
 780                                                 {
 781                                                         authtype = config->radius_authtypes & AUTHCHAP;
 782                                                         LOG(3, s, t, "    Remote requested CHAP authentication...%sing\n",
 783                                                                 authtype ? "accept" : "reject");
 784                                                 }
 785                                                 else
 786                                                 {
 787                                                         LOG(3, s, t, "    Rejecting unsupported authentication %#4x\n",
 788                                                                 proto);
 789                                                 }
 790                                         }
 791                                         else
 792                                         {
 793                                                 LOG(2, s, t, "LCP: remote rejected auth negotiation\n");
 794                                                 authtype = 0; // shutdown
 795                                         }
 796
 797                                         break;
 798
 799                                 case 5: // Magic-Number
 800                                         session[s].magic = 0;
 801                                         if (*p == ConfigNak)
 802                                         {
 803                                                 if (length < 6) break;
 804                                                 session[s].magic = ntohl(*(uint32_t *)(o + 2));
 805                                         }
 806
 807                                         if (session[s].magic)
 808                                                 LOG(3, s, t, "    Remote requested magic-no %x\n", session[s].magic);
 809                                         else
 810                                                 LOG(3, s, t, "    Remote rejected magic-no\n");
 811
 812                                         cluster_send_session(s);
 813                                         break;
 814
 815                                 default:
 816                                         LOG(2, s, t, "LCP: remote sent %s for type %u?\n", ppp_code(*p), type);
 817                                         sessionshutdown(s, "Unable to negotiate LCP.", CDN_ADMIN_DISC, TERM_USER_ERROR);
 818                                         return;
 819                         }
 820                         x -= length;
 821                         o += length;
 822                 }
 823
 824                 if (!authtype)
 825                 {
 826                         sessionshutdown(s, "Unsupported authentication.", CDN_ADMIN_DISC, TERM_USER_ERROR);
 827                         return;
 828                 }
 829
 830                 if (authtype > 0)
 831                         sess_local[s].lcp_authtype = authtype;
 832
 833                 switch (session[s].ppp.lcp)
 834                 {
 835                 case Closed:
 836                 case Stopped:
 837                         {
 838                                 uint8_t *response = makeppp(b, sizeof(b), p, 2, s, t, PPPLCP);
 839                                 if (!response) return;
 840                                 *response = TerminateAck;
 841                                 *((uint16_t *) (response + 2)) = htons(l = 4);
 842
 843                                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*response));
 844                                 if (config->debug > 3) dumplcp(response, l);
 845
 846                                 tunnelsend(b, l + (response - b), t);
 847                         }
 848                         break;
 849
 850                 case RequestSent:
 851                 case AckSent:
 852                         initialise_restart_count(s, lcp);
 853                         sendlcp(s, t);
 854                         break;
 855
 856                 case AckReceived:
 857                         LOG(2, s, t, "LCP: ConfigNak in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.lcp));
 858                         sendlcp(s, t);
 859                         break;
 860
 861                 case Opened:
 862                         lcp_restart(s);
 863                         sendlcp(s, t);
 864                         break;
 865
 866                 default:
 867                         LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp));
 868                         return;
 869                 }
 870         }
 871         else if (*p == TerminateReq)
 872         {
 873                 switch (session[s].ppp.lcp)
 874                 {
 875                 case Closed:
 876                 case Stopped:
 877                 case Closing:
 878                 case Stopping:
 879                 case RequestSent:
 880                 case AckReceived:
 881                 case AckSent:
 882                         break;
 883
 884                 case Opened:
 885                         lcp_restart(s);
 886                         zero_restart_count(s, lcp);
 887                         change_state(s, lcp, Closing);
 888                         break;
 889
 890                 default:
 891                         LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp));
 892                         return;
 893                 }
 894
 895                 *p = TerminateAck;      // send ack
 896                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPLCP);
 897                 if (!q) return;
 898
 899                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*q));
 900                 if (config->debug > 3) dumplcp(q, l);
 901
 902                 tunnelsend(b, l + (q - b), t); // send it
 903         }
 904         else if (*p == ProtocolRej)
 905         {
 906                 uint16_t proto = 0;
 907
 908                 if (l > 4)
 909                 {
 910                         proto = *(p+4);
 911                         if (l > 5 && !(proto & 1))
 912                         {
 913                                 proto <<= 8;
 914                                 proto |= *(p+5);
 915                         }
 916                 }
 917
 918                 if (proto == PPPIPV6CP)
 919                 {
 920                         LOG(3, s, t, "IPv6 rejected\n");
 921                         change_state(s, ipv6cp, Closed);
 922                 }
 923                 else
 924                 {
 925                         LOG(3, s, t, "LCP protocol reject: 0x%04X\n", proto);
 926                 }
 927         }
 928         else if (*p == EchoReq)
 929         {
 930                 *p = EchoReply;         // reply
 931                 *(uint32_t *) (p + 4) = htonl(session[s].magic); // our magic number
 932                 q = makeppp(b, sizeof(b), p, l, s, t, PPPLCP);
 933                 if (!q) return;
 934
 935                 LOG(4, s, t, "LCP: send %s\n", ppp_code(*q));
 936                 if (config->debug > 3) dumplcp(q, l);
 937
 938                 tunnelsend(b, l + (q - b), t); // send it
 939         }
 940         else if (*p == EchoReply)
 941         {
 942                 // Ignore it, last_packet time is set earlier than this.
 943         }
 944         else if (*p != CodeRej)
 945         {
 946                 ppp_code_rej(s, t, PPPLCP, "LCP", p, l, b, sizeof(b));
 947         }
 948 }
 949
 950 static void ipcp_open(sessionidt s, tunnelidt t)
 951 {
 952         LOG(3, s, t, "IPCP: Opened, session is now active\n");
 953
 954         change_state(s, ipcp, Opened);
 955
 956         if (!(session[s].walled_garden || session[s].flags & SESSION_STARTED))
 957         {
 958                 uint16_t r = radiusnew(s);
 959                 if (r)
 960                 {
 961                         radiussend(r, RADIUSSTART); // send radius start
 962
 963                         // don't send further Start records if IPCP is restarted
 964                         session[s].flags |= SESSION_STARTED;
 965                         cluster_send_session(s);
 966                 }
 967         }
 968
 969         // start IPv6 if configured and still in passive state
 970         if (session[s].ppp.ipv6cp == Stopped)
 971         {
 972                 sendipv6cp(s, t);
 973                 change_state(s, ipv6cp, RequestSent);
 974         }
 975 }
 976
 977 // Process IPCP messages
 978 void processipcp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 979 {
 980         uint8_t b[MAXETHER];
 981         uint8_t *q = 0;
 982         uint16_t hl;
 983
 984         CSTAT(processipcp);
 985
 986         LOG_HEX(5, "IPCP", p, l);
 987         if (l < 4)
 988         {
 989                 LOG(1, s, t, "Short IPCP %d bytes\n", l);
 990                 STAT(tunnel_rx_errors);
 991                 return ;
 992         }
 993
 994         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
 995         {
 996                 LOG(1, s, t, "Length mismatch IPCP %u/%u\n", hl, l);
 997                 STAT(tunnel_rx_errors);
 998                 return ;
 999         }
1000         l = hl;
1001
1002         if (session[s].ppp.phase < Network)
1003         {
1004                 LOG(2, s, t, "IPCP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
1005                 return;
1006         }
1007
1008         LOG(3, s, t, "IPCP: recv %s\n", ppp_code(*p));
1009
1010         if (*p == ConfigAck)
1011         {
1012                 switch (session[s].ppp.ipcp)
1013                 {
1014                 case RequestSent:
1015                         initialise_restart_count(s, ipcp);
1016                         change_state(s, ipcp, AckReceived);
1017                         break;
1018
1019                 case AckReceived:
1020                 case Opened:
1021                         LOG(2, s, t, "IPCP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ipcp));
1022                         sendipcp(s, t);
1023                         change_state(s, ipcp, RequestSent);
1024                         break;
1025
1026                 case AckSent:
1027                         ipcp_open(s, t);
1028                         break;
1029
1030                 default:
1031                         LOG(2, s, t, "IPCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipcp));
1032                 }
1033         }
1034         else if (*p == ConfigReq)
1035         {
1036                 uint8_t *response = 0;
1037                 uint8_t *o = p + 4;
1038                 int length = l - 4;
1039                 int gotip = 0;
1040                 in_addr_t addr;
1041
1042                 while (length > 2)
1043                 {
1044                         if (!o[1] || o[1] > length) return;
1045
1046                         switch (*o)
1047                         {
1048                         case 3: // ip address
1049                                 gotip++; // seen address
1050                                 if (o[1] != 6) return;
1051
1052                                 addr = htonl(session[s].ip);
1053                                 if (memcmp(o + 2, &addr, (sizeof addr)))
1054                                 {
1055                                         uint8_t *oq = q;
1056                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPCP, &response, q, p, o, (uint8_t *) &addr, sizeof(addr));
1057                                         if (!q || (q != oq && *response == ConfigRej))
1058                                         {
1059                                                 sessionshutdown(s, "Can't negotiate IPCP.", CDN_ADMIN_DISC, TERM_USER_ERROR);
1060                                                 return;
1061                                         }
1062                                 }
1063
1064                                 break;
1065
1066                         case 129: // primary DNS
1067                                 if (o[1] != 6) return;
1068
1069                                 addr = htonl(session[s].dns1);
1070                                 if (memcmp(o + 2, &addr, (sizeof addr)))
1071                                 {
1072                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPCP, &response, q, p, o, (uint8_t *) &addr, sizeof(addr));
1073                                         if (!q) return;
1074                                 }
1075
1076                                 break;
1077
1078                         case 131: // secondary DNS
1079                                 if (o[1] != 6) return;
1080
1081                                 addr = htonl(session[s].dns2);
1082                                 if (memcmp(o + 2, &addr, sizeof(addr)))
1083                                 {
1084                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPCP, &response, q, p, o, (uint8_t *) &addr, sizeof(addr));
1085                                         if (!q) return;
1086                                 }
1087
1088                                 break;
1089
1090                         default:
1091                                 LOG(2, s, t, "    Rejecting PPP IPCP Option type %d\n", *o);
1092                                 q = ppp_conf_rej(s, b, sizeof(b), PPPIPCP, &response, q, p, o);
1093                                 if (!q) return;
1094                         }
1095
1096                         length -= o[1];
1097                         o += o[1];
1098                 }
1099
1100                 if (response)
1101                 {
1102                         l = q - response; // IPCP packet length
1103                         *((uint16_t *) (response + 2)) = htons(l); // update header
1104                 }
1105                 else if (gotip)
1106                 {
1107                         // Send packet back as ConfigAck
1108                         response = makeppp(b, sizeof(b), p, l, s, t, PPPIPCP);
1109                         if (!response) return;
1110                         *response = ConfigAck;
1111                 }
1112                 else
1113                 {
1114                         LOG(1, s, t, "No IP in IPCP request\n");
1115                         STAT(tunnel_rx_errors);
1116                         return;
1117                 }
1118
1119                 switch (session[s].ppp.ipcp)
1120                 {
1121                 case Closed:
1122                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPIPCP);
1123                         if (!response) return;
1124                         *response = TerminateAck;
1125                         *((uint16_t *) (response + 2)) = htons(l = 4);
1126                         break;
1127
1128                 case Stopped:
1129                         initialise_restart_count(s, ipcp);
1130                         sendipcp(s, t);
1131                         if (*response == ConfigAck)
1132                                 change_state(s, ipcp, AckSent);
1133                         else
1134                                 change_state(s, ipcp, RequestSent);
1135
1136                         break;
1137
1138                 case RequestSent:
1139                         if (*response == ConfigAck)
1140                                 change_state(s, ipcp, AckSent);
1141
1142                         break;
1143
1144                 case AckReceived:
1145                         if (*response == ConfigAck)
1146                                 ipcp_open(s, t);
1147
1148                         break;
1149
1150                 case Opened:
1151                         initialise_restart_count(s, ipcp);
1152                         sendipcp(s, t);
1153                         /* fallthrough */
1154
1155                 case AckSent:
1156                         if (*response == ConfigAck)
1157                                 change_state(s, ipcp, AckSent);
1158                         else
1159                                 change_state(s, ipcp, RequestSent);
1160
1161                         break;
1162
1163                 default:
1164                         LOG(2, s, t, "IPCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipcp));
1165                         return;
1166                 }
1167
1168                 LOG(3, s, t, "IPCP: send %s\n", ppp_code(*response));
1169                 tunnelsend(b, l + (response - b), t);
1170         }
1171         else if (*p == TerminateReq)
1172         {
1173                 switch (session[s].ppp.ipcp)
1174                 {
1175                 case Closed:
1176                 case Stopped:
1177                 case Closing:
1178                 case Stopping:
1179                 case RequestSent:
1180                 case AckReceived:
1181                 case AckSent:
1182                         break;
1183
1184                 case Opened:
1185                         zero_restart_count(s, ipcp);
1186                         change_state(s, ipcp, Closing);
1187                         break;
1188
1189                 default:
1190                         LOG(2, s, t, "IPCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipcp));
1191                         return;
1192                 }
1193
1194                 *p = TerminateAck;      // send ack
1195                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPIPCP);
1196                 if (!q) return;
1197
1198                 LOG(3, s, t, "IPCP: send %s\n", ppp_code(*q));
1199                 tunnelsend(b, l + (q - b), t); // send it
1200         }
1201         else if (*p != CodeRej)
1202         {
1203                 ppp_code_rej(s, t, PPPIPCP, "IPCP", p, l, b, sizeof(b));
1204         }
1205 }
1206
1207 static void ipv6cp_open(sessionidt s, tunnelidt t)
1208 {
1209         LOG(3, s, t, "IPV6CP: Opened\n");
1210
1211         change_state(s, ipv6cp, Opened);
1212         if (session[s].ipv6prefixlen)
1213                 route6set(s, session[s].ipv6route, session[s].ipv6prefixlen, 1);
1214
1215         // Send an initial RA (TODO: Should we send these regularly?)
1216         send_ipv6_ra(s, t, NULL);
1217 }
1218
1219 // Process IPV6CP messages
1220 void processipv6cp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1221 {
1222         uint8_t b[MAXETHER];
1223         uint8_t *q = 0;
1224         uint16_t hl;
1225
1226         CSTAT(processipv6cp);
1227
1228         LOG_HEX(5, "IPV6CP", p, l);
1229         if (l < 4)
1230         {
1231                 LOG(1, s, t, "Short IPV6CP %d bytes\n", l);
1232                 STAT(tunnel_rx_errors);
1233                 return ;
1234         }
1235
1236         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
1237         {
1238                 LOG(1, s, t, "Length mismatch IPV6CP %u/%u\n", hl, l);
1239                 STAT(tunnel_rx_errors);
1240                 return ;
1241         }
1242         l = hl;
1243
1244         if (session[s].ppp.phase < Network)
1245         {
1246                 LOG(2, s, t, "IPV6CP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
1247                 return;
1248         }
1249
1250         LOG(3, s, t, "IPV6CP: recv %s\n", ppp_code(*p));
1251
1252         if (!session[s].ip)
1253         {
1254                 LOG(3, s, t, "IPV6CP: no IPv4 address (IPCP in state %s)\n", ppp_state(session[s].ppp.ipcp));
1255                 return; // need IPCP to complete...
1256         }
1257
1258         if (*p == ConfigAck)
1259         {
1260                 switch (session[s].ppp.ipv6cp)
1261                 {
1262                 case RequestSent:
1263                         initialise_restart_count(s, ipv6cp);
1264                         change_state(s, ipv6cp, AckReceived);
1265                         break;
1266
1267                 case AckReceived:
1268                 case Opened:
1269                         LOG(2, s, t, "IPV6CP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ipv6cp));
1270                         sendipv6cp(s, t);
1271                         change_state(s, ipv6cp, RequestSent);
1272                         break;
1273
1274                 case AckSent:
1275                         ipv6cp_open(s, t);
1276                         break;
1277
1278                 default:
1279                         LOG(2, s, t, "IPV6CP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipv6cp));
1280                 }
1281         }
1282         else if (*p == ConfigReq)
1283         {
1284                 uint8_t *response = 0;
1285                 uint8_t *o = p + 4;
1286                 int length = l - 4;
1287                 int gotip = 0;
1288                 uint8_t ident[8];
1289
1290                 while (length > 2)
1291                 {
1292                         if (!o[1] || o[1] > length) return;
1293
1294                         switch (*o)
1295                         {
1296                         case 1: // interface identifier
1297                                 gotip++; // seen address
1298                                 if (o[1] != 10) return;
1299
1300                                 *(uint32_t *) ident = htonl(session[s].ip);
1301                                 *(uint32_t *) (ident + 4) = 0;
1302
1303                                 if (memcmp(o + 2, ident, sizeof(ident)))
1304                                 {
1305                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPV6CP, &response, q, p, o, ident, sizeof(ident));
1306                                         if (!q) return;
1307                                 }
1308
1309                                 break;
1310
1311                         default:
1312                                 LOG(2, s, t, "    Rejecting PPP IPV6CP Option type %d\n", *o);
1313                                 q = ppp_conf_rej(s, b, sizeof(b), PPPIPV6CP, &response, q, p, o);
1314                                 if (!q) return;
1315                         }
1316
1317                         length -= o[1];
1318                         o += o[1];
1319                 }
1320
1321                 if (response)
1322                 {
1323                         l = q - response; // IPV6CP packet length
1324                         *((uint16_t *) (response + 2)) = htons(l); // update header
1325                 }
1326                 else if (gotip)
1327                 {
1328                         // Send packet back as ConfigAck
1329                         response = makeppp(b, sizeof(b), p, l, s, t, PPPIPV6CP);
1330                         if (!response) return;
1331                         *response = ConfigAck;
1332                 }
1333                 else
1334                 {
1335                         LOG(1, s, t, "No interface identifier in IPV6CP request\n");
1336                         STAT(tunnel_rx_errors);
1337                         return;
1338                 }
1339
1340                 switch (session[s].ppp.ipv6cp)
1341                 {
1342                 case Closed:
1343                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPIPV6CP);
1344                         if (!response) return;
1345                         *response = TerminateAck;
1346                         *((uint16_t *) (response + 2)) = htons(l = 4);
1347                         break;
1348
1349                 case Stopped:
1350                         initialise_restart_count(s, ipv6cp);
1351                         sendipv6cp(s, t);
1352                         if (*response == ConfigAck)
1353                                 change_state(s, ipv6cp, AckSent);
1354                         else
1355                                 change_state(s, ipv6cp, RequestSent);
1356
1357                         break;
1358
1359                 case RequestSent:
1360                         if (*response == ConfigAck)
1361                                 change_state(s, ipv6cp, AckSent);
1362
1363                         break;
1364
1365                 case AckReceived:
1366                         if (*response == ConfigAck)
1367                                 ipv6cp_open(s, t);
1368
1369                         break;
1370
1371                 case Opened:
1372                         initialise_restart_count(s, ipv6cp);
1373                         sendipv6cp(s, t);
1374                         /* fallthrough */
1375
1376                 case AckSent:
1377                         if (*response == ConfigAck)
1378                                 change_state(s, ipv6cp, AckSent);
1379                         else
1380                                 change_state(s, ipv6cp, RequestSent);
1381
1382                         break;
1383
1384                 default:
1385                         LOG(2, s, t, "IPV6CP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipv6cp));
1386                         return;
1387                 }
1388
1389                 LOG(3, s, t, "IPV6CP: send %s\n", ppp_code(*response));
1390                 tunnelsend(b, l + (response - b), t);
1391         }
1392         else if (*p == TerminateReq)
1393         {
1394                 switch (session[s].ppp.ipv6cp)
1395                 {
1396                 case Closed:
1397                 case Stopped:
1398                 case Closing:
1399                 case Stopping:
1400                 case RequestSent:
1401                 case AckReceived:
1402                 case AckSent:
1403                         break;
1404
1405                 case Opened:
1406                         zero_restart_count(s, ipv6cp);
1407                         change_state(s, ipv6cp, Closing);
1408                         break;
1409
1410                 default:
1411                         LOG(2, s, t, "IPV6CP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipv6cp));
1412                         return;
1413                 }
1414
1415                 *p = TerminateAck;      // send ack
1416                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPIPV6CP);
1417                 if (!q) return;
1418
1419                 LOG(3, s, t, "IPV6CP: send %s\n", ppp_code(*q));
1420                 tunnelsend(b, l + (q - b), t); // send it
1421         }
1422         else if (*p != CodeRej)
1423         {
1424                 ppp_code_rej(s, t, PPPIPV6CP, "IPV6CP", p, l, b, sizeof(b));
1425         }
1426 }
1427
1428 // process IP packet received
1429 //
1430 // This MUST be called with at least 4 byte behind 'p'.
1431 // (i.e. this routine writes to p[-4]).
1432 void processipin(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1433 {
1434         in_addr_t ip;
1435
1436         CSTAT(processipin);
1437
1438         LOG_HEX(5, "IP", p, l);
1439
1440         if (l < 20)
1441         {
1442                 LOG(1, s, t, "IP packet too short %d\n", l);
1443                 STAT(tunnel_rx_errors);
1444                 return ;
1445         }
1446
1447         ip = ntohl(*(uint32_t *)(p + 12));
1448
1449         if (l > MAXETHER)
1450         {
1451                 LOG(1, s, t, "IP packet too long %d\n", l);
1452                 STAT(tunnel_rx_errors);
1453                 return ;
1454         }
1455
1456         if (session[s].ppp.phase != Network || session[s].ppp.ipcp != Opened)
1457                 return;
1458
1459         // no spoof (do sessionbyip to handled statically routed subnets)
1460         if (ip != session[s].ip && sessionbyip(htonl(ip)) != s)
1461         {
1462                 LOG(5, s, t, "Dropping packet with spoofed IP %s\n", fmtaddr(htonl(ip), 0));
1463                 return;
1464         }
1465
1466         // run access-list if any
1467         if (session[s].filter_in && !ip_filter(p, l, session[s].filter_in - 1))
1468                 return;
1469
1470         // adjust MSS on SYN and SYN,ACK packets with options
1471         if ((ntohs(*(uint16_t *) (p + 6)) & 0x1fff) == 0 && p[9] == IPPROTO_TCP) // first tcp fragment
1472         {
1473                 int ihl = (p[0] & 0xf) * 4; // length of IP header
1474                 if (l >= ihl + 20 && (p[ihl + 13] & TCP_FLAG_SYN) && ((p[ihl + 12] >> 4) > 5))
1475                         adjust_tcp_mss(s, t, p, l, p + ihl);
1476         }
1477
1478         // Add on the tun header
1479         p -= 4;
1480         *(uint32_t *) p = htonl(PKTIP);
1481         l += 4;
1482
1483         // Are we throttled and a slave?
1484         if (session[s].tbf_in && !config->cluster_iam_master) {
1485                 // Pass it to the master for handling.
1486                 master_throttle_packet(session[s].tbf_in, p, l);
1487                 return;
1488         }
1489
1490         // Are we throttled and a master??
1491         if (session[s].tbf_in && config->cluster_iam_master) {
1492                 // Actually handle the throttled packets.
1493                 tbf_queue_packet(session[s].tbf_in, p, l);
1494                 return;
1495         }
1496
1497         // send to ethernet
1498         if (tun_write(p, l) < 0)
1499         {
1500                 STAT(tun_tx_errors);
1501                 LOG(0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1502                         l, strerror(errno), tunfd, p);
1503
1504                 return;
1505         }
1506
1507         p += 4;
1508         l -= 4;
1509
1510         if (session[s].snoop_ip && session[s].snoop_port)
1511         {
1512                 // Snooping this session
1513                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
1514         }
1515
1516         increment_counter(&session[s].cin, &session[s].cin_wrap, l);
1517         session[s].cin_delta += l;
1518         session[s].pin++;
1519
1520         sess_local[s].cin += l;
1521         sess_local[s].pin++;
1522
1523         eth_tx += l;
1524
1525         STAT(tun_tx_packets);
1526         INC_STAT(tun_tx_bytes, l);
1527 }
1528
1529 // process IPv6 packet received
1530 //
1531 // This MUST be called with at least 4 byte behind 'p'.
1532 // (i.e. this routine writes to p[-4]).
1533 void processipv6in(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1534 {
1535         struct in6_addr ip;
1536         in_addr_t ipv4;
1537
1538         CSTAT(processipv6in);
1539
1540         LOG_HEX(5, "IPv6", p, l);
1541
1542         ip = *(struct in6_addr *) (p + 8);
1543         ipv4 = ntohl(*(uint32_t *)(p + 16));
1544
1545         if (l > MAXETHER)
1546         {
1547                 LOG(1, s, t, "IP packet too long %d\n", l);
1548                 STAT(tunnel_rx_errors);
1549                 return ;
1550         }
1551
1552         if (session[s].ppp.phase != Network || session[s].ppp.ipv6cp != Opened)
1553                 return;
1554
1555         // no spoof
1556         if (ipv4 != session[s].ip && memcmp(&config->ipv6_prefix, &ip, 8) && sessionbyipv6(ip) != s)
1557         {
1558                 char str[INET6_ADDRSTRLEN];
1559                 LOG(5, s, t, "Dropping packet with spoofed IP %s\n",
1560                                 inet_ntop(AF_INET6, &ip, str, INET6_ADDRSTRLEN));
1561                 return;
1562         }
1563
1564         // Check if it's a Router Solicition message.
1565         if (*(p + 6) == 58 && *(p + 7) == 255 && *(p + 24) == 0xFF && *(p + 25) == 2 &&
1566                         *(uint32_t *)(p + 26) == 0 && *(uint32_t *)(p + 30) == 0 &&
1567                         *(uint32_t *)(p + 34) == 0 &&
1568                         *(p + 38) == 0 && *(p + 39) == 2 && *(p + 40) == 133) {
1569                 LOG(3, s, t, "Got IPv6 RS\n");
1570                 send_ipv6_ra(s, t, &ip);
1571                 return;
1572         }
1573
1574         // Add on the tun header
1575         p -= 4;
1576         *(uint32_t *) p = htonl(PKTIPV6);
1577         l += 4;
1578
1579         // Are we throttled and a slave?
1580         if (session[s].tbf_in && !config->cluster_iam_master) {
1581                 // Pass it to the master for handling.
1582                 master_throttle_packet(session[s].tbf_in, p, l);
1583                 return;
1584         }
1585
1586         // Are we throttled and a master??
1587         if (session[s].tbf_in && config->cluster_iam_master) {
1588                 // Actually handle the throttled packets.
1589                 tbf_queue_packet(session[s].tbf_in, p, l);
1590                 return;
1591         }
1592
1593         // send to ethernet
1594         if (tun_write(p, l) < 0)
1595         {
1596                 STAT(tun_tx_errors);
1597                 LOG(0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1598                         l, strerror(errno), tunfd, p);
1599
1600                 return;
1601         }
1602
1603         p += 4;
1604         l -= 4;
1605
1606         if (session[s].snoop_ip && session[s].snoop_port)
1607         {
1608                 // Snooping this session
1609                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
1610         }
1611
1612         increment_counter(&session[s].cin, &session[s].cin_wrap, l);
1613         session[s].cin_delta += l;
1614         session[s].pin++;
1615
1616         sess_local[s].cin += l;
1617         sess_local[s].pin++;
1618
1619         eth_tx += l;
1620
1621         STAT(tun_tx_packets);
1622         INC_STAT(tun_tx_bytes, l);
1623 }
1624
1625 //
1626 // Helper routine for the TBF filters.
1627 // Used to send queued data in from the user.
1628 //
1629 void send_ipin(sessionidt s, uint8_t *buf, int len)
1630 {
1631         LOG_HEX(5, "IP in throttled", buf, len);
1632
1633         if (write(tunfd, buf, len) < 0)
1634         {
1635                 STAT(tun_tx_errors);
1636                 LOG(0, 0, 0, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1637                         len, strerror(errno), tunfd, buf);
1638
1639                 return;
1640         }
1641
1642         buf += 4;
1643         len -= 4;
1644
1645         if (session[s].snoop_ip && session[s].snoop_port)
1646         {
1647                 // Snooping this session
1648                 snoop_send_packet(buf, len, session[s].snoop_ip, session[s].snoop_port);
1649         }
1650
1651         // Increment packet counters
1652         increment_counter(&session[s].cin, &session[s].cin_wrap, len);
1653         session[s].cin_delta += len;
1654         session[s].pin++;
1655
1656         sess_local[s].cin += len;
1657         sess_local[s].pin++;
1658
1659         eth_tx += len;
1660
1661         STAT(tun_tx_packets);
1662         INC_STAT(tun_tx_bytes, len - 4);
1663 }
1664
1665
1666 // Process CCP messages
1667 void processccp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1668 {
1669         uint8_t b[MAXETHER];
1670         uint8_t *q;
1671
1672         CSTAT(processccp);
1673
1674         LOG_HEX(5, "CCP", p, l);
1675
1676         if (session[s].ppp.phase < Network)
1677         {
1678                 LOG(2, s, t, "CCP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
1679                 return;
1680         }
1681
1682         if (l < 1)
1683         {
1684                 LOG(1, s, t, "Short CCP packet\n");
1685                 STAT(tunnel_rx_errors);
1686         }
1687
1688         LOG(3, s, t, "CCP: recv %s\n", ppp_code(*p));
1689         if (*p == ConfigAck)
1690         {
1691                 switch (session[s].ppp.ccp)
1692                 {
1693                 case RequestSent:
1694                         initialise_restart_count(s, ccp);
1695                         change_state(s, ccp, AckReceived);
1696                         break;
1697
1698                 case AckReceived:
1699                 case Opened:
1700                         LOG(2, s, t, "CCP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ccp));
1701                         sendccp(s, t);
1702                         change_state(s, ccp, RequestSent);
1703                         break;
1704
1705                 case AckSent:
1706                         LOG(3, s, t, "CCP: Opened\n");
1707                         change_state(s, ccp, Opened);
1708                         break;
1709
1710                 default:
1711                         LOG(2, s, t, "CCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ccp));
1712                 }
1713         }
1714         else if (*p == ConfigReq)
1715         {
1716                 if (l < 6) // accept no compression
1717                         *p = ConfigAck;
1718                 else // compression requested--reject
1719                         *p = ConfigRej;
1720
1721                 q = makeppp(b, sizeof(b), p, l, s, t, PPPCCP);
1722                 if (!q) return;
1723
1724                 switch (session[s].ppp.ccp)
1725                 {
1726                 case Closed:
1727                         q = makeppp(b, sizeof(b), p, 2, s, t, PPPCCP);
1728                         if (!q) return;
1729                         *q = TerminateAck;
1730                         *((uint16_t *) (q + 2)) = htons(l = 4);
1731                         break;
1732
1733                 case Stopped:
1734                         initialise_restart_count(s, ccp);
1735                         sendccp(s, t);
1736                         if (*q == ConfigAck)
1737                                 change_state(s, ccp, AckSent);
1738                         else
1739                                 change_state(s, ccp, RequestSent);
1740
1741                         break;
1742
1743                 case RequestSent:
1744                         if (*q == ConfigAck)
1745                                 change_state(s, ccp, AckSent);
1746
1747                         break;
1748
1749                 case AckReceived:
1750                         if (*q == ConfigAck)
1751                                 change_state(s, ccp, Opened);
1752
1753                         break;
1754
1755                 case Opened:
1756                         initialise_restart_count(s, ccp);
1757                         sendccp(s, t);
1758                         /* fallthrough */
1759
1760                 case AckSent:
1761                         if (*q == ConfigAck)
1762                                 change_state(s, ccp, AckSent);
1763                         else
1764                                 change_state(s, ccp, RequestSent);
1765
1766                         break;
1767
1768                 default:
1769                         LOG(2, s, t, "CCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ccp));
1770                         return;
1771                 }
1772
1773                 LOG(3, s, t, "CCP: send %s\n", ppp_code(*q));
1774                 tunnelsend(b, l + (q - b), t);
1775         }
1776         else if (*p == TerminateReq)
1777         {
1778                 *p = TerminateAck;
1779                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPCCP);
1780                 if (!q) return;
1781                 LOG(3, s, t, "CCP: send %s\n", ppp_code(*q));
1782                 tunnelsend(b, l + (q - b), t);
1783                 change_state(s, ccp, Stopped);
1784         }
1785         else if (*p != CodeRej)
1786         {
1787                 ppp_code_rej(s, t, PPPCCP, "CCP", p, l, b, sizeof(b));
1788         }
1789 }
1790
1791 // send a CHAP challenge
1792 void sendchap(sessionidt s, tunnelidt t)
1793 {
1794         uint8_t b[MAXETHER];
1795         uint16_t r;
1796         uint8_t *q;
1797
1798         CSTAT(sendchap);
1799
1800         r = radiusnew(s);
1801         if (!r)
1802         {
1803                 LOG(1, s, t, "No RADIUS to send challenge\n");
1804                 STAT(tunnel_tx_errors);
1805                 return;
1806         }
1807
1808         LOG(1, s, t, "Send CHAP challenge\n");
1809
1810         radius[r].chap = 1;             // CHAP not PAP
1811         radius[r].id++;
1812         if (radius[r].state != RADIUSCHAP)
1813                 radius[r].try = 0;
1814
1815         radius[r].state = RADIUSCHAP;
1816         radius[r].retry = backoff(radius[r].try++);
1817         if (radius[r].try > 5)
1818         {
1819                 sessionshutdown(s, "CHAP timeout.", CDN_ADMIN_DISC, TERM_REAUTHENTICATION_FAILURE);
1820                 STAT(tunnel_tx_errors);
1821                 return ;
1822         }
1823         q = makeppp(b, sizeof(b), 0, 0, s, t, PPPCHAP);
1824         if (!q) return;
1825
1826         *q = 1;                                 // challenge
1827         q[1] = radius[r].id;                    // ID
1828         q[4] = 16;                              // value size (size of challenge)
1829         memcpy(q + 5, radius[r].auth, 16);      // challenge
1830         strcpy((char *) q + 21, hostname);      // our name
1831         *(uint16_t *) (q + 2) = htons(strlen(hostname) + 21); // length
1832         tunnelsend(b, strlen(hostname) + 21 + (q - b), t); // send it
1833 }
1834
1835 // fill in a L2TP message with a PPP frame,
1836 // returns start of PPP frame
1837 uint8_t *makeppp(uint8_t *b, int size, uint8_t *p, int l, sessionidt s, tunnelidt t, uint16_t mtype)
1838 {
1839         if (size < 12) // Need more space than this!!
1840         {
1841                 LOG(0, s, t, "makeppp buffer too small for L2TP header (size=%d)\n", size);
1842                 return NULL;
1843         }
1844
1845         *(uint16_t *) (b + 0) = htons(0x0002); // L2TP with no options
1846         *(uint16_t *) (b + 2) = htons(tunnel[t].far); // tunnel
1847         *(uint16_t *) (b + 4) = htons(session[s].far); // session
1848         b += 6;
1849         if (mtype == PPPLCP || !(session[s].flags & SESSION_ACFC))
1850         {
1851                 *(uint16_t *) b = htons(0xFF03); // HDLC header
1852                 b += 2;
1853         }
1854         if (mtype < 0x100 && session[s].flags & SESSION_PFC)
1855                 *b++ = mtype;
1856         else
1857         {
1858                 *(uint16_t *) b = htons(mtype);
1859                 b += 2;
1860         }
1861
1862         if (l + 12 > size)
1863         {
1864                 LOG(2, s, t, "makeppp would overflow buffer (size=%d, header+payload=%d)\n", size, l + 12);
1865                 return NULL;
1866         }
1867
1868         if (p && l)
1869                 memcpy(b, p, l);
1870
1871         return b;
1872 }
1873
1874 static int add_lcp_auth(uint8_t *b, int size, int authtype)
1875 {
1876         int len = 0;
1877         if ((authtype == AUTHCHAP && size < 5) || size < 4)
1878                 return 0;
1879
1880         *b++ = 3; // Authentication-Protocol
1881         if (authtype == AUTHCHAP)
1882         {
1883                 len = *b++ = 5; // length
1884                 *(uint16_t *) b = htons(PPPCHAP); b += 2;
1885                 *b++ = 5; // MD5
1886         }
1887         else if (authtype == AUTHPAP)
1888         {
1889                 len = *b++ = 4; // length
1890                 *(uint16_t *) b = htons(PPPPAP); b += 2;
1891         }
1892         else
1893         {
1894                 LOG(0, 0, 0, "add_lcp_auth called with unsupported auth type %d\n", authtype);
1895         }
1896
1897         return len;
1898 }
1899
1900 // Send LCP ConfigReq for MRU, authentication type and magic no
1901 void sendlcp(sessionidt s, tunnelidt t)
1902 {
1903         uint8_t b[500], *q, *l;
1904         int authtype = sess_local[s].lcp_authtype;
1905
1906         if (!(q = makeppp(b, sizeof(b), NULL, 0, s, t, PPPLCP)))
1907                 return;
1908
1909         LOG(3, s, t, "LCP: send ConfigReq%s%s%s\n",
1910             authtype ? " (" : "",
1911             authtype ? (authtype == AUTHCHAP ? "CHAP" : "PAP") : "",
1912             authtype ? ")" : "");
1913
1914         l = q;
1915         *l++ = ConfigReq;
1916         *l++ = ++sess_local[s].lcp_ident; // ID
1917
1918         l += 2; //Save space for length
1919
1920         if (sess_local[s].ppp_mru)
1921         {
1922                 *l++ = 1; *l++ = 4; // Maximum-Receive-Unit (length 4)
1923                 *(uint16_t *) l = htons(sess_local[s].ppp_mru); l += 2;
1924         }
1925
1926         if (authtype)
1927                 l += add_lcp_auth(l, sizeof(b) - (l - b), authtype);
1928
1929         if (session[s].magic)
1930         {
1931                 *l++ = 5; *l++ = 6; // Magic-Number (length 6)
1932                 *(uint32_t *) l = htonl(session[s].magic);
1933                 l += 4;
1934         }
1935
1936         *(uint16_t *)(q + 2) = htons(l - q); // Length
1937
1938         LOG_HEX(5, "PPPLCP", q, l - q);
1939         if (config->debug > 3) dumplcp(q, l - q);
1940
1941         tunnelsend(b, (l - b), t);
1942         restart_timer(s, lcp);
1943 }
1944
1945 // Send CCP request for no compression
1946 void sendccp(sessionidt s, tunnelidt t)
1947 {
1948         uint8_t b[500], *q;
1949
1950         if (!(q = makeppp(b, sizeof(b), NULL, 0, s, t, PPPCCP)))
1951                 return;
1952
1953         LOG(3, s, t, "CCP: send ConfigReq (no compression)\n");
1954
1955         *q = ConfigReq;
1956         *(q + 1) = ++sess_local[s].lcp_ident; // ID
1957         *(uint16_t *)(q + 2) = htons(4); // Length
1958
1959         LOG_HEX(5, "PPPCCP", q, 4);
1960         tunnelsend(b, (q - b) + 4 , t);
1961         restart_timer(s, ccp);
1962 }
1963
1964 // Reject unknown/unconfigured protocols
1965 void protoreject(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l, uint16_t proto)
1966 {
1967
1968         uint8_t buf[MAXETHER];
1969         uint8_t *q;
1970         int mru = session[s].mru;
1971         if (mru < MINMTU) mru = MINMTU;
1972         if (mru > sizeof(buf)) mru = sizeof(buf);
1973
1974         l += 6;
1975         if (l > mru) l = mru;
1976
1977         q = makeppp(buf, sizeof(buf), 0, 0, s, t, PPPLCP);
1978         if (!q) return;
1979
1980         *q = ProtocolRej;
1981         *(q + 1) = ++sess_local[s].lcp_ident;
1982         *(uint16_t *)(q + 2) = htons(l);
1983         *(uint16_t *)(q + 4) = htons(proto);
1984         memcpy(q + 6, p, l - 6);
1985
1986         if (proto == PPPIPV6CP)
1987                 LOG(3, s, t, "LCP: send ProtocolRej (IPV6CP: not configured)\n");
1988         else
1989                 LOG(2, s, t, "LCP: sent ProtocolRej (0x%04X: unsupported)\n", proto);
1990
1991         tunnelsend(buf, l + (q - buf), t);
1992 }