ppp.c

   1 // L2TPNS PPP Stuff
   2
   3 char const *cvs_id_ppp = "$Id: ppp.c,v 1.81 2005-09-15 09:34:49 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.", 3, 0);
  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.", 3, 0);
  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.", 3, 0);
  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.", 4, 0);
 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.", 3, 0);
 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.", 3, 0);
 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.", 3, 0);
 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.", 3, 0);
 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.", 3, 0);
 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.", 3, 0);
 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
 453         if (!mru) mru = MAXMRU;
 454         if (mru > size) mru = size;
 455
 456         l += 4;
 457         if (l > mru) l = mru;
 458
 459         q = makeppp(buf, size, 0, 0, s, t, proto);
 460         if (!q) return;
 461
 462         *q = CodeRej;
 463         *(q + 1) = ++sess_local[s].lcp_ident;
 464         *(uint16_t *)(q + 2) = l;
 465         memcpy(q + 4, p, l - 4);
 466
 467         LOG(2, s, t, "Unexpected %s code %s\n", pname, ppp_code(*p));
 468         LOG(3, s, t, "%s: send %s\n", pname, ppp_code(*q));
 469         if (config->debug > 3) dumplcp(q, l);
 470
 471         tunnelsend(buf, l + (q - buf), t);
 472 }
 473
 474 // Process LCP messages
 475 void processlcp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 476 {
 477         uint8_t b[MAXETHER];
 478         uint8_t *q = NULL;
 479         uint32_t magicno = 0;
 480         uint16_t hl;
 481
 482         CSTAT(processlcp);
 483
 484         LOG_HEX(5, "LCP", p, l);
 485         if (l < 4)
 486         {
 487                 LOG(1, s, t, "Short LCP %d bytes\n", l);
 488                 STAT(tunnel_rx_errors);
 489                 return ;
 490         }
 491
 492         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
 493         {
 494                 LOG(1, s, t, "Length mismatch LCP %u/%u\n", hl, l);
 495                 STAT(tunnel_rx_errors);
 496                 return ;
 497         }
 498         l = hl;
 499
 500         if (session[s].die) // going down...
 501                 return;
 502
 503         LOG(*p == EchoReq ? 4 : 3, s, t, "LCP: recv %s\n", ppp_code(*p));
 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 (!config->ppp_mru || mru <= config->ppp_mru)
 583                                                 {
 584                                                         session[s].mru = mru;
 585                                                         break;
 586                                                 }
 587
 588                                                 LOG(3, s, t, "    Remote requesting MRU of %u.  Rejecting.\n", mru);
 589                                                 mru = htons(config->ppp_mru);
 590                                                 q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, (uint8_t *) &mru, sizeof(mru));
 591                                         }
 592                                         break;
 593
 594                                 case 2: // Async-Control-Character-Map
 595                                         if (!ntohl(*(uint32_t *)(o + 2))) // all bits zero is OK
 596                                                 break;
 597
 598                                         LOG(3, s, t, "    Remote requesting asyncmap.  Rejecting.\n");
 599                                         q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, asyncmap, sizeof(asyncmap));
 600                                         break;
 601
 602                                 case 3: // Authentication-Protocol
 603                                         {
 604                                                 int proto = ntohs(*(uint16_t *)(o + 2));
 605                                                 char proto_name[] = "0x0000";
 606                                                 int alen;
 607
 608                                                 if (proto == PPPPAP)
 609                                                 {
 610                                                         if (config->radius_authtypes & AUTHPAP)
 611                                                         {
 612                                                                 sess_local[s].lcp_authtype = AUTHPAP;
 613                                                                 break;
 614                                                         }
 615
 616                                                         strcpy(proto_name, "PAP");
 617                                                 }
 618                                                 else if (proto == PPPCHAP)
 619                                                 {
 620                                                         if (config->radius_authtypes & AUTHCHAP
 621                                                             && *(o + 4) == 5) // MD5
 622                                                         {
 623                                                                 sess_local[s].lcp_authtype = AUTHCHAP;
 624                                                                 break;
 625                                                         }
 626
 627                                                         strcpy(proto_name, "CHAP");
 628                                                 }
 629                                                 else
 630                                                         sprintf(proto_name, "%#4.4x", proto);
 631
 632                                                 LOG(3, s, t, "    Remote requesting %s authentication.  Rejecting.\n", proto_name);
 633
 634                                                 alen = add_lcp_auth(authproto, sizeof(authproto), config->radius_authprefer);
 635                                                 if (alen < 2) break; // paranoia
 636
 637                                                 q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, authproto + 2, alen - 2);
 638                                                 if (q && *response == ConfigNak &&
 639                                                         config->radius_authtypes != config->radius_authprefer)
 640                                                 {
 641                                                         // alternate type
 642                                                         alen = add_lcp_auth(authproto, sizeof(authproto), config->radius_authtypes & ~config->radius_authprefer);
 643                                                         if (alen < 2) break;
 644                                                         q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, authproto + 2, alen - 2);
 645                                                 }
 646
 647                                                 break;
 648                                         }
 649                                         break;
 650
 651                                 case 5: // Magic-Number
 652                                         magicno = ntohl(*(uint32_t *)(o + 2));
 653                                         break;
 654
 655                                 case 4: // Quality-Protocol
 656                                 case 7: // Protocol-Field-Compression
 657                                 case 8: // Address-And-Control-Field-Compression
 658                                         break;
 659
 660                                 default: // Reject any unknown options
 661                                         LOG(3, s, t, "    Rejecting unknown PPP LCP option %d\n", type);
 662                                         q = ppp_conf_rej(s, b, sizeof(b), PPPLCP, &response, q, p, o);
 663                         }
 664                         x -= length;
 665                         o += length;
 666                 }
 667
 668                 if (response)
 669                 {
 670                         l = q - response; // LCP packet length
 671                         *((uint16_t *) (response + 2)) = htons(l); // update header
 672                 }
 673                 else
 674                 {
 675                         // Send packet back as ConfigAck
 676                         response = makeppp(b, sizeof(b), p, l, s, t, PPPLCP);
 677                         if (!response) return;
 678                         *response = ConfigAck;
 679                 }
 680
 681                 switch (session[s].ppp.lcp)
 682                 {
 683                 case Closed:
 684                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPLCP);
 685                         if (!response) return;
 686                         *response = TerminateAck;
 687                         *((uint16_t *) (response + 2)) = htons(l = 4);
 688                         break;
 689
 690                 case Stopped:
 691                         initialise_restart_count(s, lcp);
 692                         sendlcp(s, t);
 693                         if (*response == ConfigAck)
 694                                 change_state(s, lcp, AckSent);
 695                         else
 696                                 change_state(s, lcp, RequestSent);
 697
 698                         break;
 699
 700                 case RequestSent:
 701                         if (*response == ConfigAck)
 702                                 change_state(s, lcp, AckSent);
 703
 704                         break;
 705
 706                 case AckReceived:
 707                         if (*response == ConfigAck)
 708                                 lcp_open(s, t);
 709
 710                         break;
 711
 712                 case Opened:
 713                         lcp_restart(s);
 714                         sendlcp(s, t);
 715                         /* fallthrough */
 716
 717                 case AckSent:
 718                         if (*response == ConfigAck)
 719                                 change_state(s, lcp, AckSent);
 720                         else
 721                                 change_state(s, lcp, RequestSent);
 722
 723                         break;
 724
 725                 default:
 726                         LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp));
 727                         return;
 728                 }
 729
 730                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*response));
 731                 if (config->debug > 3) dumplcp(response, l);
 732
 733                 tunnelsend(b, l + (response - b), t);
 734         }
 735         else if (*p == ConfigNak || *p == ConfigRej)
 736         {
 737                 int x = l - 4;
 738                 uint8_t *o = (p + 4);
 739                 int authtype = -1;
 740
 741                 while (x > 2)
 742                 {
 743                         int type = o[0];
 744                         int length = o[1];
 745
 746                         if (length == 0 || type == 0 || x < length) break;
 747                         switch (type)
 748                         {
 749                                 case 1: // Maximum-Receive-Unit
 750                                         if (*p == ConfigNak)
 751                                         {
 752                                                 session[s].mru = 0;
 753                                                 LOG(3, s, t, "    Remote requested MRU of %u; removing option\n",
 754                                                         ntohs(*(uint16_t *)(o + 2)));
 755                                         }
 756                                         else
 757                                         {
 758                                                 session[s].mru = 0;
 759                                                 LOG(3, s, t, "    Remote rejected MRU negotiation\n");
 760                                         }
 761
 762                                         break;
 763
 764                                 case 3: // Authentication-Protocol
 765                                         if (authtype > 0)
 766                                                 break;
 767
 768                                         if (*p == ConfigNak)
 769                                         {
 770                                                 int proto = ntohs(*(uint16_t *)(o + 2));
 771                                                 if (proto == PPPPAP)
 772                                                 {
 773                                                         authtype = config->radius_authtypes & AUTHPAP;
 774                                                         LOG(3, s, t, "    Remote requested PAP authentication...%sing\n",
 775                                                                 authtype ? "accept" : "reject");
 776                                                 }
 777                                                 else if (proto == PPPCHAP && *(o + 4) == 5)
 778                                                 {
 779                                                         authtype = config->radius_authtypes & AUTHCHAP;
 780                                                         LOG(3, s, t, "    Remote requested CHAP authentication...%sing\n",
 781                                                                 authtype ? "accept" : "reject");
 782                                                 }
 783                                                 else
 784                                                 {
 785                                                         LOG(3, s, t, "    Rejecting unsupported authentication %#4x\n",
 786                                                                 proto);
 787                                                 }
 788                                         }
 789                                         else
 790                                         {
 791                                                 LOG(2, s, t, "LCP: remote rejected auth negotiation\n");
 792                                                 authtype = 0; // shutdown
 793                                         }
 794
 795                                         break;
 796
 797                                 default:
 798                                         LOG(2, s, t, "LCP: remote sent %s for type %u?\n", ppp_code(*p), type);
 799                                         break;
 800                         }
 801                         x -= length;
 802                         o += length;
 803                 }
 804
 805                 if (!authtype)
 806                 {
 807                         sessionshutdown(s, "Unsupported authentication.", 3, 0);
 808                         return;
 809                 }
 810
 811                 if (authtype > 0)
 812                         sess_local[s].lcp_authtype = authtype;
 813
 814                 switch (session[s].ppp.lcp)
 815                 {
 816                 case Closed:
 817                 case Stopped:
 818                         {
 819                                 uint8_t *response = makeppp(b, sizeof(b), p, 2, s, t, PPPLCP);
 820                                 if (!response) return;
 821                                 *response = TerminateAck;
 822                                 *((uint16_t *) (response + 2)) = htons(l = 4);
 823
 824                                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*response));
 825                                 if (config->debug > 3) dumplcp(response, l);
 826
 827                                 tunnelsend(b, l + (response - b), t);
 828                         }
 829                         break;
 830
 831                 case RequestSent:
 832                 case AckSent:
 833                         initialise_restart_count(s, lcp);
 834                         sendlcp(s, t);
 835                         break;
 836
 837                 case AckReceived:
 838                         LOG(2, s, t, "LCP: ConfigNak in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.lcp));
 839                         sendlcp(s, t);
 840                         break;
 841
 842                 case Opened:
 843                         lcp_restart(s);
 844                         sendlcp(s, t);
 845                         break;
 846
 847                 default:
 848                         LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp));
 849                         return;
 850                 }
 851         }
 852         else if (*p == TerminateReq)
 853         {
 854                 *p = TerminateAck;      // close
 855                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPLCP);
 856                 if (!q) return;
 857
 858                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*q));
 859                 if (config->debug > 3) dumplcp(q, l);
 860
 861                 tunnelsend(b, l + (q - b), t); // send it
 862                 sessionshutdown(s, "Remote end closed connection.", 3, 0);
 863         }
 864         else if (*p == TerminateAck)
 865         {
 866                 sessionshutdown(s, "Connection closed.", 3, 0);
 867         }
 868         else if (*p == ProtocolRej)
 869         {
 870                 uint16_t proto = 0;
 871
 872                 if (l > 4)
 873                 {
 874                         proto = *(p+4);
 875                         if (l > 5 && !(proto & 1))
 876                         {
 877                                 proto <<= 8;
 878                                 proto |= *(p+5);
 879                         }
 880                 }
 881
 882                 if (proto == PPPIPV6CP)
 883                 {
 884                         LOG(3, s, t, "IPv6 rejected\n");
 885                         change_state(s, ipv6cp, Closed);
 886                 }
 887                 else
 888                 {
 889                         LOG(3, s, t, "LCP protocol reject: 0x%04X\n", proto);
 890                 }
 891         }
 892         else if (*p == EchoReq)
 893         {
 894                 *p = EchoReply;         // reply
 895                 *(uint32_t *) (p + 4) = htonl(session[s].magic); // our magic number
 896                 q = makeppp(b, sizeof(b), p, l, s, t, PPPLCP);
 897                 if (!q) return;
 898
 899                 LOG(4, 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 == EchoReply)
 905         {
 906                 // Ignore it, last_packet time is set earlier than this.
 907         }
 908         else if (*p != CodeRej)
 909         {
 910                 ppp_code_rej(s, t, PPPLCP, "LCP", p, l, b, sizeof(b));
 911         }
 912 }
 913
 914 static void ipcp_open(sessionidt s, tunnelidt t)
 915 {
 916         LOG(3, s, t, "IPCP: Opened, session is now active\n");
 917
 918         change_state(s, ipcp, Opened);
 919
 920         if (!session[s].walled_garden)
 921         {
 922                 uint16_t r = radiusnew(s);
 923                 if (r)
 924                         radiussend(r, RADIUSSTART); // send radius start
 925         }
 926
 927         // start IPv6 if configured and still in passive state
 928         if (session[s].ppp.ipv6cp == Stopped)
 929         {
 930                 sendipv6cp(s, t);
 931                 change_state(s, ipv6cp, RequestSent);
 932         }
 933 }
 934
 935 // Process IPCP messages
 936 void processipcp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 937 {
 938         uint8_t b[MAXETHER];
 939         uint8_t *q = 0;
 940         uint16_t hl;
 941
 942         CSTAT(processipcp);
 943
 944         LOG_HEX(5, "IPCP", p, l);
 945         if (l < 5)
 946         {
 947                 LOG(1, s, t, "Short IPCP %d bytes\n", l);
 948                 STAT(tunnel_rx_errors);
 949                 return ;
 950         }
 951
 952         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
 953         {
 954                 LOG(1, s, t, "Length mismatch IPCP %u/%u\n", hl, l);
 955                 STAT(tunnel_rx_errors);
 956                 return ;
 957         }
 958         l = hl;
 959
 960         if (session[s].ppp.phase < Network)
 961         {
 962                 LOG(2, s, t, "IPCP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
 963                 return;
 964         }
 965
 966         LOG(3, s, t, "IPCP: recv %s\n", ppp_code(*p));
 967
 968         if (*p == ConfigAck)
 969         {
 970                 switch (session[s].ppp.ipcp)
 971                 {
 972                 case RequestSent:
 973                         initialise_restart_count(s, ipcp);
 974                         change_state(s, ipcp, AckReceived);
 975                         break;
 976
 977                 case AckReceived:
 978                 case Opened:
 979                         LOG(2, s, t, "IPCP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ipcp));
 980                         sendipcp(s, t);
 981                         change_state(s, ipcp, RequestSent);
 982                         break;
 983
 984                 case AckSent:
 985                         ipcp_open(s, t);
 986                         break;
 987
 988                 default:
 989                         LOG(2, s, t, "IPCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipcp));
 990                 }
 991         }
 992         else if (*p == ConfigReq)
 993         {
 994                 uint8_t *response = 0;
 995                 uint8_t *o = p + 4;
 996                 int length = l - 4;
 997                 int gotip = 0;
 998                 in_addr_t addr;
 999
1000                 while (length > 2)
1001                 {
1002                         switch (*o)
1003                         {
1004                         case 3: // ip address
1005                                 gotip++; // seen address
1006                                 if (o[1] != 6 || o[1] > length) return;
1007
1008                                 addr = htonl(session[s].ip);
1009                                 if (memcmp(o + 2, &addr, (sizeof addr)))
1010                                 {
1011                                         uint8_t *oq = q;
1012                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPCP, &response, q, p, o, (uint8_t *) &addr, sizeof(addr));
1013                                         if (!q || (q != oq && *response == ConfigRej))
1014                                         {
1015                                                 sessionshutdown(s, "Can't negotiate IPCP.", 3, 0);
1016                                                 return;
1017                                         }
1018                                 }
1019
1020                                 break;
1021
1022                         case 129: // primary DNS
1023                                 if (o[1] != 6 || o[1] > length) return;
1024
1025                                 addr = htonl(session[s].dns1);
1026                                 if (memcmp(o + 2, &addr, (sizeof addr)))
1027                                 {
1028                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPCP, &response, q, p, o, (uint8_t *) &addr, sizeof(addr));
1029                                         if (!q) return;
1030                                 }
1031
1032                                 break;
1033
1034                         case 131: // secondary DNS
1035                                 if (o[1] != 6 || o[1] > length) return;
1036
1037                                 addr = htonl(session[s].dns1);
1038                                 if (memcmp(o + 2, &addr, sizeof(addr)))
1039                                 {
1040                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPCP, &response, q, p, o, (uint8_t *) &addr, sizeof(addr));
1041                                         if (!q) return;
1042                                 }
1043
1044                                 break;
1045
1046                         default:
1047                                 LOG(2, s, t, "    Rejecting PPP IPCP Option type %d\n", *o);
1048                                 q = ppp_conf_rej(s, b, sizeof(b), PPPIPCP, &response, q, p, o);
1049                                 if (!q) return;
1050                         }
1051
1052                         length -= o[1];
1053                         o += o[1];
1054                 }
1055
1056                 if (response)
1057                 {
1058                         l = q - response; // IPCP packet length
1059                         *((uint16_t *) (response + 2)) = htons(l); // update header
1060                 }
1061                 else if (gotip)
1062                 {
1063                         // Send packet back as ConfigAck
1064                         response = makeppp(b, sizeof(b), p, l, s, t, PPPIPCP);
1065                         if (!response) return;
1066                         *response = ConfigAck;
1067                 }
1068                 else
1069                 {
1070                         LOG(1, s, t, "No IP in IPCP request\n");
1071                         STAT(tunnel_rx_errors);
1072                         return;
1073                 }
1074
1075                 switch (session[s].ppp.ipcp)
1076                 {
1077                 case Closed:
1078                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPIPCP);
1079                         if (!response) return;
1080                         *response = TerminateAck;
1081                         *((uint16_t *) (response + 2)) = htons(l = 4);
1082                         break;
1083
1084                 case Stopped:
1085                         initialise_restart_count(s, ipcp);
1086                         sendipcp(s, t);
1087                         if (*response == ConfigAck)
1088                                 change_state(s, ipcp, AckSent);
1089                         else
1090                                 change_state(s, ipcp, RequestSent);
1091
1092                         break;
1093
1094                 case RequestSent:
1095                         if (*response == ConfigAck)
1096                                 change_state(s, ipcp, AckSent);
1097
1098                         break;
1099
1100                 case AckReceived:
1101                         if (*response == ConfigAck)
1102                                 ipcp_open(s, t);
1103
1104                         break;
1105
1106                 case Opened:
1107                         initialise_restart_count(s, ipcp);
1108                         sendipcp(s, t);
1109                         /* fallthrough */
1110
1111                 case AckSent:
1112                         if (*response == ConfigAck)
1113                                 change_state(s, ipcp, AckSent);
1114                         else
1115                                 change_state(s, ipcp, RequestSent);
1116
1117                         break;
1118
1119                 default:
1120                         LOG(2, s, t, "IPCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipcp));
1121                         return;
1122                 }
1123
1124                 LOG(3, s, t, "IPCP: send %s\n", ppp_code(*response));
1125                 tunnelsend(b, l + (response - b), t);
1126         }
1127         else if (*p == TerminateReq)
1128         {
1129                 *p = TerminateAck;
1130                 q = makeppp(b, sizeof(b), p, l, s, t, PPPIPCP);
1131                 if (!q) return;
1132                 LOG(3, s, t, "IPCP: send %s\n", ppp_code(*q));
1133                 tunnelsend(b, l + (q - b), t);
1134                 change_state(s, ipcp, Stopped);
1135         }
1136         else if (*p != CodeRej)
1137         {
1138                 ppp_code_rej(s, t, PPPIPCP, "IPCP", p, l, b, sizeof(b));
1139         }
1140 }
1141
1142 static void ipv6cp_open(sessionidt s, tunnelidt t)
1143 {
1144         LOG(3, s, t, "IPV6CP: Opened\n");
1145
1146         change_state(s, ipv6cp, Opened);
1147         if (session[s].ipv6prefixlen)
1148                 route6set(s, session[s].ipv6route, session[s].ipv6prefixlen, 1);
1149
1150         // Send an initial RA (TODO: Should we send these regularly?)
1151         send_ipv6_ra(s, t, NULL);
1152 }
1153
1154 // Process IPV6CP messages
1155 void processipv6cp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1156 {
1157         uint8_t b[MAXETHER];
1158         uint8_t *q = 0;
1159         uint16_t hl;
1160
1161         CSTAT(processipv6cp);
1162
1163         LOG_HEX(5, "IPV6CP", p, l);
1164         if (l < 4)
1165         {
1166                 LOG(1, s, t, "Short IPV6CP %d bytes\n", l);
1167                 STAT(tunnel_rx_errors);
1168                 return ;
1169         }
1170
1171         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
1172         {
1173                 LOG(1, s, t, "Length mismatch IPV6CP %u/%u\n", hl, l);
1174                 STAT(tunnel_rx_errors);
1175                 return ;
1176         }
1177         l = hl;
1178
1179         if (session[s].ppp.phase < Network)
1180         {
1181                 LOG(2, s, t, "IPV6CP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
1182                 return;
1183         }
1184
1185         LOG(3, s, t, "IPV6CP: recv %s\n", ppp_code(*p));
1186
1187         if (!session[s].ip)
1188         {
1189                 LOG(3, s, t, "IPV6CP: no IPv4 address (IPCP in state %s)\n", ppp_state(session[s].ppp.ipcp));
1190                 return; // need IPCP to complete...
1191         }
1192
1193         if (*p == ConfigAck)
1194         {
1195                 switch (session[s].ppp.ipv6cp)
1196                 {
1197                 case RequestSent:
1198                         initialise_restart_count(s, ipv6cp);
1199                         change_state(s, ipv6cp, AckReceived);
1200                         break;
1201
1202                 case AckReceived:
1203                 case Opened:
1204                         LOG(2, s, t, "IPV6CP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ipv6cp));
1205                         sendipv6cp(s, t);
1206                         change_state(s, ipv6cp, RequestSent);
1207                         break;
1208
1209                 case AckSent:
1210                         ipv6cp_open(s, t);
1211                         break;
1212
1213                 default:
1214                         LOG(2, s, t, "IPV6CP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipv6cp));
1215                 }
1216         }
1217         else if (*p == ConfigReq)
1218         {
1219                 uint8_t *response = 0;
1220                 uint8_t *o = p + 4;
1221                 int length = l - 4;
1222                 int gotip = 0;
1223                 uint8_t ident[8];
1224
1225                 while (length > 2)
1226                 {
1227                         switch (*o)
1228                         {
1229                         case 1: // interface identifier
1230                                 gotip++; // seen address
1231                                 if (o[1] != 10 || o[1] > length) return;
1232
1233                                 *(uint32_t *) ident = htonl(session[s].ip);
1234                                 *(uint32_t *) (ident + 4) = 0;
1235
1236                                 if (memcmp(o + 2, ident, sizeof(ident)))
1237                                 {
1238                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPV6CP, &response, q, p, o, ident, sizeof(ident));
1239                                         if (!q) return;
1240                                 }
1241
1242                                 break;
1243
1244                         default:
1245                                 LOG(2, s, t, "    Rejecting PPP IPV6CP Option type %d\n", *o);
1246                                 q = ppp_conf_rej(s, b, sizeof(b), PPPIPV6CP, &response, q, p, o);
1247                                 if (!q) return;
1248                         }
1249
1250                         length -= o[1];
1251                         o += o[1];
1252                 }
1253
1254                 if (response)
1255                 {
1256                         l = q - response; // IPV6CP packet length
1257                         *((uint16_t *) (response + 2)) = htons(l); // update header
1258                 }
1259                 else if (gotip)
1260                 {
1261                         // Send packet back as ConfigAck
1262                         response = makeppp(b, sizeof(b), p, l, s, t, PPPIPV6CP);
1263                         if (!response) return;
1264                         *response = ConfigAck;
1265                 }
1266                 else
1267                 {
1268                         LOG(1, s, t, "No interface identifier in IPV6CP request\n");
1269                         STAT(tunnel_rx_errors);
1270                         return;
1271                 }
1272
1273                 switch (session[s].ppp.ipv6cp)
1274                 {
1275                 case Closed:
1276                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPIPV6CP);
1277                         if (!response) return;
1278                         *response = TerminateAck;
1279                         *((uint16_t *) (response + 2)) = htons(l = 4);
1280                         break;
1281
1282                 case Stopped:
1283                         initialise_restart_count(s, ipv6cp);
1284                         sendipv6cp(s, t);
1285                         if (*response == ConfigAck)
1286                                 change_state(s, ipv6cp, AckSent);
1287                         else
1288                                 change_state(s, ipv6cp, RequestSent);
1289
1290                         break;
1291
1292                 case RequestSent:
1293                         if (*response == ConfigAck)
1294                                 change_state(s, ipv6cp, AckSent);
1295
1296                         break;
1297
1298                 case AckReceived:
1299                         if (*response == ConfigAck)
1300                                 ipv6cp_open(s, t);
1301
1302                         break;
1303
1304                 case Opened:
1305                         initialise_restart_count(s, ipv6cp);
1306                         sendipv6cp(s, t);
1307                         /* fallthrough */
1308
1309                 case AckSent:
1310                         if (*response == ConfigAck)
1311                                 change_state(s, ipv6cp, AckSent);
1312                         else
1313                                 change_state(s, ipv6cp, RequestSent);
1314
1315                         break;
1316
1317                 default:
1318                         LOG(2, s, t, "IPV6CP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipv6cp));
1319                         return;
1320                 }
1321
1322                 LOG(3, s, t, "IPV6CP: send %s\n", ppp_code(*response));
1323                 tunnelsend(b, l + (response - b), t);
1324         }
1325         else if (*p == TerminateReq)
1326         {
1327                 *p = TerminateAck;
1328                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPIPV6CP);
1329                 if (!q) return;
1330                 LOG(3, s, t, "IPV6CP: send %s\n", ppp_code(*q));
1331                 tunnelsend(b, l + (q - b), t);
1332                 change_state(s, ipv6cp, Stopped);
1333         }
1334         else if (*p != CodeRej)
1335         {
1336                 ppp_code_rej(s, t, PPPIPV6CP, "IPV6CP", p, l, b, sizeof(b));
1337         }
1338 }
1339
1340 // process IP packet received
1341 //
1342 // This MUST be called with at least 4 byte behind 'p'.
1343 // (i.e. this routine writes to p[-4]).
1344 void processipin(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1345 {
1346         in_addr_t ip;
1347
1348         CSTAT(processipin);
1349
1350         LOG_HEX(5, "IP", p, l);
1351
1352         ip = ntohl(*(uint32_t *)(p + 12));
1353
1354         if (l > MAXETHER)
1355         {
1356                 LOG(1, s, t, "IP packet too long %d\n", l);
1357                 STAT(tunnel_rx_errors);
1358                 return ;
1359         }
1360
1361         if (session[s].ppp.phase != Network || session[s].ppp.ipcp != Opened)
1362                 return;
1363
1364         // no spoof (do sessionbyip to handled statically routed subnets)
1365         if (ip != session[s].ip && sessionbyip(htonl(ip)) != s)
1366         {
1367                 LOG(5, s, t, "Dropping packet with spoofed IP %s\n", fmtaddr(htonl(ip), 0));
1368                 return;
1369         }
1370
1371         // run access-list if any
1372         if (session[s].filter_in && !ip_filter(p, l, session[s].filter_in - 1))
1373                 return;
1374
1375         // Add on the tun header
1376         p -= 4;
1377         *(uint32_t *) p = htonl(PKTIP);
1378         l += 4;
1379
1380         // Are we throttled and a slave?
1381         if (session[s].tbf_in && !config->cluster_iam_master) {
1382                 // Pass it to the master for handling.
1383                 master_throttle_packet(session[s].tbf_in, p, l);
1384                 return;
1385         }
1386
1387         // Are we throttled and a master??
1388         if (session[s].tbf_in && config->cluster_iam_master) {
1389                 // Actually handle the throttled packets.
1390                 tbf_queue_packet(session[s].tbf_in, p, l);
1391                 return;
1392         }
1393
1394         // send to ethernet
1395         if (tun_write(p, l) < 0)
1396         {
1397                 STAT(tun_tx_errors);
1398                 LOG(0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1399                         l, strerror(errno), tunfd, p);
1400
1401                 return;
1402         }
1403
1404         p += 4;
1405         l -= 4;
1406
1407         if (session[s].snoop_ip && session[s].snoop_port)
1408         {
1409                 // Snooping this session
1410                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
1411         }
1412
1413         increment_counter(&session[s].cin, &session[s].cin_wrap, l);
1414         session[s].cin_delta += l;
1415         session[s].pin++;
1416
1417         sess_local[s].cin += l;
1418         sess_local[s].pin++;
1419
1420         eth_tx += l;
1421
1422         STAT(tun_tx_packets);
1423         INC_STAT(tun_tx_bytes, l);
1424 }
1425
1426 // process IPv6 packet received
1427 //
1428 // This MUST be called with at least 4 byte behind 'p'.
1429 // (i.e. this routine writes to p[-4]).
1430 void processipv6in(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1431 {
1432         struct in6_addr ip;
1433         in_addr_t ipv4;
1434
1435         CSTAT(processipv6in);
1436
1437         LOG_HEX(5, "IPv6", p, l);
1438
1439         ip = *(struct in6_addr *) (p + 8);
1440         ipv4 = ntohl(*(uint32_t *)(p + 16));
1441
1442         if (l > MAXETHER)
1443         {
1444                 LOG(1, s, t, "IP packet too long %d\n", l);
1445                 STAT(tunnel_rx_errors);
1446                 return ;
1447         }
1448
1449         if (session[s].ppp.phase != Network || session[s].ppp.ipv6cp != Opened)
1450                 return;
1451
1452         // no spoof
1453         if (ipv4 != session[s].ip && memcmp(&config->ipv6_prefix, &ip, 8) && sessionbyipv6(ip) != s)
1454         {
1455                 char str[INET6_ADDRSTRLEN];
1456                 LOG(5, s, t, "Dropping packet with spoofed IP %s\n",
1457                                 inet_ntop(AF_INET6, &ip, str, INET6_ADDRSTRLEN));
1458                 return;
1459         }
1460
1461         // Check if it's a Router Solicition message.
1462         if (*(p + 6) == 58 && *(p + 7) == 255 && *(p + 24) == 0xFF && *(p + 25) == 2 &&
1463                         *(uint32_t *)(p + 26) == 0 && *(uint32_t *)(p + 30) == 0 &&
1464                         *(uint32_t *)(p + 34) == 0 &&
1465                         *(p + 38) == 0 && *(p + 39) == 2 && *(p + 40) == 133) {
1466                 LOG(3, s, t, "Got IPv6 RS\n");
1467                 send_ipv6_ra(s, t, &ip);
1468                 return;
1469         }
1470
1471         // Add on the tun header
1472         p -= 4;
1473         *(uint32_t *) p = htonl(PKTIPV6);
1474         l += 4;
1475
1476         // Are we throttled and a slave?
1477         if (session[s].tbf_in && !config->cluster_iam_master) {
1478                 // Pass it to the master for handling.
1479                 master_throttle_packet(session[s].tbf_in, p, l);
1480                 return;
1481         }
1482
1483         // Are we throttled and a master??
1484         if (session[s].tbf_in && config->cluster_iam_master) {
1485                 // Actually handle the throttled packets.
1486                 tbf_queue_packet(session[s].tbf_in, p, l);
1487                 return;
1488         }
1489
1490         // send to ethernet
1491         if (tun_write(p, l) < 0)
1492         {
1493                 STAT(tun_tx_errors);
1494                 LOG(0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1495                         l, strerror(errno), tunfd, p);
1496
1497                 return;
1498         }
1499
1500         p += 4;
1501         l -= 4;
1502
1503         if (session[s].snoop_ip && session[s].snoop_port)
1504         {
1505                 // Snooping this session
1506                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
1507         }
1508
1509         increment_counter(&session[s].cin, &session[s].cin_wrap, l);
1510         session[s].cin_delta += l;
1511         session[s].pin++;
1512
1513         sess_local[s].cin += l;
1514         sess_local[s].pin++;
1515
1516         eth_tx += l;
1517
1518         STAT(tun_tx_packets);
1519         INC_STAT(tun_tx_bytes, l);
1520 }
1521
1522 //
1523 // Helper routine for the TBF filters.
1524 // Used to send queued data in from the user.
1525 //
1526 void send_ipin(sessionidt s, uint8_t *buf, int len)
1527 {
1528         LOG_HEX(5, "IP in throttled", buf, len);
1529
1530         if (write(tunfd, buf, len) < 0)
1531         {
1532                 STAT(tun_tx_errors);
1533                 LOG(0, 0, 0, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1534                         len, strerror(errno), tunfd, buf);
1535
1536                 return;
1537         }
1538
1539         buf += 4;
1540         len -= 4;
1541
1542         if (session[s].snoop_ip && session[s].snoop_port)
1543         {
1544                 // Snooping this session
1545                 snoop_send_packet(buf, len, session[s].snoop_ip, session[s].snoop_port);
1546         }
1547
1548         // Increment packet counters
1549         increment_counter(&session[s].cin, &session[s].cin_wrap, len);
1550         session[s].cin_delta += len;
1551         session[s].pin++;
1552
1553         sess_local[s].cin += len;
1554         sess_local[s].pin++;
1555
1556         eth_tx += len;
1557
1558         STAT(tun_tx_packets);
1559         INC_STAT(tun_tx_bytes, len - 4);
1560 }
1561
1562
1563 // Process CCP messages
1564 void processccp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1565 {
1566         uint8_t b[MAXETHER];
1567         uint8_t *q;
1568
1569         CSTAT(processccp);
1570
1571         LOG_HEX(5, "CCP", p, l);
1572
1573         if (session[s].ppp.phase < Network)
1574         {
1575                 LOG(2, s, t, "CCP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
1576                 return;
1577         }
1578
1579         if (l < 1)
1580         {
1581                 LOG(1, s, t, "Short CCP packet\n");
1582                 STAT(tunnel_rx_errors);
1583         }
1584
1585         LOG(3, s, t, "CCP: recv %s\n", ppp_code(*p));
1586         if (*p == ConfigAck)
1587         {
1588                 switch (session[s].ppp.ccp)
1589                 {
1590                 case RequestSent:
1591                         initialise_restart_count(s, ccp);
1592                         change_state(s, ccp, AckReceived);
1593                         break;
1594
1595                 case AckReceived:
1596                 case Opened:
1597                         LOG(2, s, t, "CCP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ccp));
1598                         sendccp(s, t);
1599                         change_state(s, ccp, RequestSent);
1600                         break;
1601
1602                 case AckSent:
1603                         LOG(3, s, t, "CCP: Opened\n");
1604                         change_state(s, ccp, Opened);
1605                         break;
1606
1607                 default:
1608                         LOG(2, s, t, "CCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ccp));
1609                 }
1610         }
1611         else if (*p == ConfigReq)
1612         {
1613                 if (l < 6) // accept no compression
1614                         *p = ConfigAck;
1615                 else // compression requested--reject
1616                         *p = ConfigRej;
1617
1618                 q = makeppp(b, sizeof(b), p, l, s, t, PPPCCP);
1619                 if (!q) return;
1620
1621                 switch (session[s].ppp.ccp)
1622                 {
1623                 case Closed:
1624                         q = makeppp(b, sizeof(b), p, 2, s, t, PPPCCP);
1625                         if (!q) return;
1626                         *q = TerminateAck;
1627                         *((uint16_t *) (q + 2)) = htons(l = 4);
1628                         break;
1629
1630                 case Stopped:
1631                         initialise_restart_count(s, ccp);
1632                         sendccp(s, t);
1633                         if (*q == ConfigAck)
1634                                 change_state(s, ccp, AckSent);
1635                         else
1636                                 change_state(s, ccp, RequestSent);
1637
1638                         break;
1639
1640                 case RequestSent:
1641                         if (*q == ConfigAck)
1642                                 change_state(s, ccp, AckSent);
1643
1644                         break;
1645
1646                 case AckReceived:
1647                         if (*q == ConfigAck)
1648                                 change_state(s, ccp, Opened);
1649
1650                         break;
1651
1652                 case Opened:
1653                         initialise_restart_count(s, ccp);
1654                         sendccp(s, t);
1655                         /* fallthrough */
1656
1657                 case AckSent:
1658                         if (*q == ConfigAck)
1659                                 change_state(s, ccp, AckSent);
1660                         else
1661                                 change_state(s, ccp, RequestSent);
1662
1663                         break;
1664
1665                 default:
1666                         LOG(2, s, t, "CCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ccp));
1667                         return;
1668                 }
1669
1670                 LOG(3, s, t, "CCP: send %s\n", ppp_code(*q));
1671                 tunnelsend(b, l + (q - b), t);
1672         }
1673         else if (*p == TerminateReq)
1674         {
1675                 *p = TerminateAck;
1676                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPCCP);
1677                 if (!q) return;
1678                 LOG(3, s, t, "CCP: send %s\n", ppp_code(*q));
1679                 tunnelsend(b, l + (q - b), t);
1680                 change_state(s, ccp, Stopped);
1681         }
1682         else if (*p != CodeRej)
1683         {
1684                 ppp_code_rej(s, t, PPPCCP, "CCP", p, l, b, sizeof(b));
1685         }
1686 }
1687
1688 // send a CHAP challenge
1689 void sendchap(sessionidt s, tunnelidt t)
1690 {
1691         uint8_t b[MAXETHER];
1692         uint16_t r;
1693         uint8_t *q;
1694
1695         CSTAT(sendchap);
1696
1697         r = radiusnew(s);
1698         if (!r)
1699         {
1700                 LOG(1, s, t, "No RADIUS to send challenge\n");
1701                 STAT(tunnel_tx_errors);
1702                 return;
1703         }
1704
1705         LOG(1, s, t, "Send CHAP challenge\n");
1706
1707         radius[r].chap = 1;             // CHAP not PAP
1708         radius[r].id++;
1709         if (radius[r].state != RADIUSCHAP)
1710                 radius[r].try = 0;
1711
1712         radius[r].state = RADIUSCHAP;
1713         radius[r].retry = backoff(radius[r].try++);
1714         if (radius[r].try > 5)
1715         {
1716                 sessionshutdown(s, "CHAP timeout.", 3, 0);
1717                 STAT(tunnel_tx_errors);
1718                 return ;
1719         }
1720         q = makeppp(b, sizeof(b), 0, 0, s, t, PPPCHAP);
1721         if (!q) return;
1722
1723         *q = 1;                                 // challenge
1724         q[1] = radius[r].id;                    // ID
1725         q[4] = 16;                              // value size (size of challenge)
1726         memcpy(q + 5, radius[r].auth, 16);      // challenge
1727         strcpy((char *) q + 21, hostname);      // our name
1728         *(uint16_t *) (q + 2) = htons(strlen(hostname) + 21); // length
1729         tunnelsend(b, strlen(hostname) + 21 + (q - b), t); // send it
1730 }
1731
1732 // fill in a L2TP message with a PPP frame,
1733 // copies existing PPP message and changes magic number if seen
1734 // returns start of PPP frame
1735 uint8_t *makeppp(uint8_t *b, int size, uint8_t *p, int l, sessionidt s, tunnelidt t, uint16_t mtype)
1736 {
1737         if (size < 12) // Need more space than this!!
1738         {
1739                 static int backtrace_count = 0;
1740                 LOG(0, s, t, "makeppp buffer too small for L2TP header (size=%d)\n", size);
1741                 log_backtrace(backtrace_count, 5)
1742                 return NULL;
1743         }
1744
1745         *(uint16_t *) (b + 0) = htons(0x0002); // L2TP with no options
1746         *(uint16_t *) (b + 2) = htons(tunnel[t].far); // tunnel
1747         *(uint16_t *) (b + 4) = htons(session[s].far); // session
1748         b += 6;
1749         if (mtype == PPPLCP || !(session[s].l2tp_flags & SESSIONACFC))
1750         {
1751                 *(uint16_t *) b = htons(0xFF03); // HDLC header
1752                 b += 2;
1753         }
1754         if (mtype < 0x100 && session[s].l2tp_flags & SESSIONPFC)
1755                 *b++ = mtype;
1756         else
1757         {
1758                 *(uint16_t *) b = htons(mtype);
1759                 b += 2;
1760         }
1761
1762         if (l + 12 > size)
1763         {
1764                 static int backtrace_count = 0;
1765                 LOG(2, s, t, "makeppp would overflow buffer (size=%d, header+payload=%d)\n", size, l + 12);
1766                 log_backtrace(backtrace_count, 5)
1767                 return NULL;
1768         }
1769
1770         if (p && l)
1771                 memcpy(b, p, l);
1772
1773         return b;
1774 }
1775
1776 static int add_lcp_auth(uint8_t *b, int size, int authtype)
1777 {
1778         int len = 0;
1779         if ((authtype == AUTHCHAP && size < 5) || size < 4)
1780                 return 0;
1781
1782         *b++ = 3; // Authentication-Protocol
1783         if (authtype == AUTHCHAP)
1784         {
1785                 len = *b++ = 5; // length
1786                 *(uint16_t *) b = htons(PPPCHAP); b += 2;
1787                 *b++ = 5; // MD5
1788         }
1789         else if (authtype == AUTHPAP)
1790         {
1791                 len = *b++ = 4; // length
1792                 *(uint16_t *) b = htons(PPPPAP); b += 2;
1793         }
1794         else
1795         {
1796                 LOG(0, 0, 0, "add_lcp_auth called with unsupported auth type %d\n", authtype);
1797         }
1798
1799         return len;
1800 }
1801
1802 // Send initial LCP ConfigReq for MRU, authentication type and magic no
1803 void sendlcp(sessionidt s, tunnelidt t)
1804 {
1805         uint8_t b[500], *q, *l;
1806         int authtype = sess_local[s].lcp_authtype;
1807
1808         if (!(q = makeppp(b, sizeof(b), NULL, 0, s, t, PPPLCP)))
1809                 return;
1810
1811         LOG(3, s, t, "LCP: send ConfigReq%s%s%s\n",
1812             authtype ? " (" : "",
1813             authtype ? (authtype == AUTHCHAP ? "CHAP" : "PAP") : "",
1814             authtype ? ")" : "");
1815
1816         l = q;
1817         *l++ = ConfigReq;
1818         *l++ = ++sess_local[s].lcp_ident; // ID
1819
1820         l += 2; //Save space for length
1821
1822         if (session[s].mru)
1823         {
1824                 *l++ = 1; *l++ = 4; // Maximum-Receive-Unit (length 4)
1825                 *(uint16_t *) l = htons(session[s].mru); l += 2;
1826         }
1827
1828         if (authtype)
1829                 l += add_lcp_auth(l, sizeof(b) - (l - b), authtype);
1830
1831         *l++ = 5; *l++ = 6; // Magic-Number (length 6)
1832         *(uint32_t *) l = htonl(session[s].magic);
1833         l += 4;
1834
1835         *(uint16_t *)(q + 2) = htons(l - q); // Length
1836
1837         LOG_HEX(5, "PPPLCP", q, l - q);
1838         if (config->debug > 3) dumplcp(q, l - q);
1839
1840         tunnelsend(b, (l - b), t);
1841 }
1842
1843 // Send CCP request for no compression
1844 void sendccp(sessionidt s, tunnelidt t)
1845 {
1846         uint8_t b[500], *q;
1847
1848         if (!(q = makeppp(b, sizeof(b), NULL, 0, s, t, PPPCCP)))
1849                 return;
1850
1851         LOG(3, s, t, "CCP: send ConfigReq (no compression)\n");
1852
1853         *q = ConfigReq;
1854         *(q + 1) = ++sess_local[s].lcp_ident; // ID
1855         *(uint16_t *)(q + 2) = htons(4); // Length
1856
1857         LOG_HEX(5, "PPPCCP", q, 4);
1858         tunnelsend(b, (q - b) + 4 , t);
1859 }