ppp.c

   1 // L2TPNS PPP Stuff
   2
   3 char const *cvs_id_ppp = "$Id: ppp.c,v 1.80 2005-09-13 14:23:07 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                                         session[s].mru = ntohs(*(uint16_t *)(o + 2));
 581                                         break;
 582
 583                                 case 2: // Async-Control-Character-Map
 584                                         if (!ntohl(*(uint32_t *)(o + 2))) // all bits zero is OK
 585                                                 break;
 586
 587                                         LOG(3, s, t, "    Remote requesting asyncmap.  Rejecting.\n");
 588                                         q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, asyncmap, sizeof(asyncmap));
 589                                         break;
 590
 591                                 case 3: // Authentication-Protocol
 592                                         {
 593                                                 int proto = ntohs(*(uint16_t *)(o + 2));
 594                                                 char proto_name[] = "0x0000";
 595                                                 int alen;
 596
 597                                                 if (proto == PPPPAP)
 598                                                 {
 599                                                         if (config->radius_authtypes & AUTHPAP)
 600                                                         {
 601                                                                 sess_local[s].lcp_authtype = AUTHPAP;
 602                                                                 break;
 603                                                         }
 604
 605                                                         strcpy(proto_name, "PAP");
 606                                                 }
 607                                                 else if (proto == PPPCHAP)
 608                                                 {
 609                                                         if (config->radius_authtypes & AUTHCHAP
 610                                                             && *(o + 4) == 5) // MD5
 611                                                         {
 612                                                                 sess_local[s].lcp_authtype = AUTHCHAP;
 613                                                                 break;
 614                                                         }
 615
 616                                                         strcpy(proto_name, "CHAP");
 617                                                 }
 618                                                 else
 619                                                         sprintf(proto_name, "%#4.4x", proto);
 620
 621                                                 LOG(3, s, t, "    Remote requesting %s authentication.  Rejecting.\n", proto_name);
 622
 623                                                 alen = add_lcp_auth(authproto, sizeof(authproto), config->radius_authprefer);
 624                                                 if (alen < 2) break; // paranoia
 625
 626                                                 q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, authproto + 2, alen - 2);
 627                                                 if (q && *response == ConfigNak &&
 628                                                         config->radius_authtypes != config->radius_authprefer)
 629                                                 {
 630                                                         // alternate type
 631                                                         alen = add_lcp_auth(authproto, sizeof(authproto), config->radius_authtypes & ~config->radius_authprefer);
 632                                                         if (alen < 2) break;
 633                                                         q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, authproto + 2, alen - 2);
 634                                                 }
 635
 636                                                 break;
 637                                         }
 638                                         break;
 639
 640                                 case 5: // Magic-Number
 641                                         magicno = ntohl(*(uint32_t *)(o + 2));
 642                                         break;
 643
 644                                 case 4: // Quality-Protocol
 645                                 case 7: // Protocol-Field-Compression
 646                                 case 8: // Address-And-Control-Field-Compression
 647                                         break;
 648
 649                                 default: // Reject any unknown options
 650                                         LOG(3, s, t, "    Rejecting unknown PPP LCP option %d\n", type);
 651                                         q = ppp_conf_rej(s, b, sizeof(b), PPPLCP, &response, q, p, o);
 652                         }
 653                         x -= length;
 654                         o += length;
 655                 }
 656
 657                 if (response)
 658                 {
 659                         l = q - response; // LCP packet length
 660                         *((uint16_t *) (response + 2)) = htons(l); // update header
 661                 }
 662                 else
 663                 {
 664                         // Send packet back as ConfigAck
 665                         response = makeppp(b, sizeof(b), p, l, s, t, PPPLCP);
 666                         if (!response) return;
 667                         *response = ConfigAck;
 668                 }
 669
 670                 switch (session[s].ppp.lcp)
 671                 {
 672                 case Closed:
 673                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPLCP);
 674                         if (!response) return;
 675                         *response = TerminateAck;
 676                         *((uint16_t *) (response + 2)) = htons(l = 4);
 677                         break;
 678
 679                 case Stopped:
 680                         initialise_restart_count(s, lcp);
 681                         sendlcp(s, t);
 682                         if (*response == ConfigAck)
 683                                 change_state(s, lcp, AckSent);
 684                         else
 685                                 change_state(s, lcp, RequestSent);
 686
 687                         break;
 688
 689                 case RequestSent:
 690                         if (*response == ConfigAck)
 691                                 change_state(s, lcp, AckSent);
 692
 693                         break;
 694
 695                 case AckReceived:
 696                         if (*response == ConfigAck)
 697                                 lcp_open(s, t);
 698
 699                         break;
 700
 701                 case Opened:
 702                         lcp_restart(s);
 703                         sendlcp(s, t);
 704                         /* fallthrough */
 705
 706                 case AckSent:
 707                         if (*response == ConfigAck)
 708                                 change_state(s, lcp, AckSent);
 709                         else
 710                                 change_state(s, lcp, RequestSent);
 711
 712                         break;
 713
 714                 default:
 715                         LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp));
 716                         return;
 717                 }
 718
 719                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*response));
 720                 if (config->debug > 3) dumplcp(response, l);
 721
 722                 tunnelsend(b, l + (response - b), t);
 723         }
 724         else if (*p == ConfigNak || *p == ConfigRej)
 725         {
 726                 int x = l - 4;
 727                 uint8_t *o = (p + 4);
 728                 int authtype = -1;
 729
 730                 while (x > 2)
 731                 {
 732                         int type = o[0];
 733                         int length = o[1];
 734
 735                         if (length == 0 || type == 0 || x < length) break;
 736                         switch (type)
 737                         {
 738                                 case 1: // Maximum-Receive-Unit
 739                                         if (*p == ConfigNak)
 740                                         {
 741                                                 session[s].mru = ntohs(*(uint16_t *)(o + 2));
 742                                                 LOG(3, s, t, "    Remote requested MRU of %u\n", session[s].mru);
 743                                         }
 744                                         else
 745                                         {
 746                                                 session[s].mru = 0;
 747                                                 LOG(3, s, t, "    Remote rejected MRU negotiation\n");
 748                                         }
 749
 750                                         break;
 751
 752                                 case 3: // Authentication-Protocol
 753                                         if (authtype > 0)
 754                                                 break;
 755
 756                                         if (*p == ConfigNak)
 757                                         {
 758                                                 int proto = ntohs(*(uint16_t *)(o + 2));
 759                                                 if (proto == PPPPAP)
 760                                                 {
 761                                                         authtype = config->radius_authtypes & AUTHPAP;
 762                                                         LOG(3, s, t, "    Remote requested PAP authentication...%sing\n",
 763                                                                 authtype ? "accept" : "reject");
 764                                                 }
 765                                                 else if (proto == PPPCHAP && *(o + 4) == 5)
 766                                                 {
 767                                                         authtype = config->radius_authtypes & AUTHCHAP;
 768                                                         LOG(3, s, t, "    Remote requested CHAP authentication...%sing\n",
 769                                                                 authtype ? "accept" : "reject");
 770                                                 }
 771                                                 else
 772                                                 {
 773                                                         LOG(3, s, t, "    Rejecting unsupported authentication %#4x\n",
 774                                                                 proto);
 775                                                 }
 776                                         }
 777                                         else
 778                                         {
 779                                                 LOG(2, s, t, "LCP: remote rejected auth negotiation\n");
 780                                                 authtype = 0; // shutdown
 781                                         }
 782
 783                                         break;
 784
 785                                 default:
 786                                         LOG(2, s, t, "LCP: remote sent %s for type %u?\n", ppp_code(*p), type);
 787                                         break;
 788                         }
 789                         x -= length;
 790                         o += length;
 791                 }
 792
 793                 if (!authtype)
 794                 {
 795                         sessionshutdown(s, "Unsupported authentication.", 3, 0);
 796                         return;
 797                 }
 798
 799                 if (authtype > 0)
 800                         sess_local[s].lcp_authtype = authtype;
 801
 802                 switch (session[s].ppp.lcp)
 803                 {
 804                 case Closed:
 805                 case Stopped:
 806                         {
 807                                 uint8_t *response = makeppp(b, sizeof(b), p, 2, s, t, PPPLCP);
 808                                 if (!response) return;
 809                                 *response = TerminateAck;
 810                                 *((uint16_t *) (response + 2)) = htons(l = 4);
 811
 812                                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*response));
 813                                 if (config->debug > 3) dumplcp(response, l);
 814
 815                                 tunnelsend(b, l + (response - b), t);
 816                         }
 817                         break;
 818
 819                 case RequestSent:
 820                 case AckSent:
 821                         initialise_restart_count(s, lcp);
 822                         sendlcp(s, t);
 823                         break;
 824
 825                 case AckReceived:
 826                         LOG(2, s, t, "LCP: ConfigNak in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.lcp));
 827                         sendlcp(s, t);
 828                         break;
 829
 830                 case Opened:
 831                         lcp_restart(s);
 832                         sendlcp(s, t);
 833                         break;
 834
 835                 default:
 836                         LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp));
 837                         return;
 838                 }
 839         }
 840         else if (*p == TerminateReq)
 841         {
 842                 *p = TerminateAck;      // close
 843                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPLCP);
 844                 if (!q) return;
 845
 846                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*q));
 847                 if (config->debug > 3) dumplcp(q, l);
 848
 849                 tunnelsend(b, l + (q - b), t); // send it
 850                 sessionshutdown(s, "Remote end closed connection.", 3, 0);
 851         }
 852         else if (*p == TerminateAck)
 853         {
 854                 sessionshutdown(s, "Connection closed.", 3, 0);
 855         }
 856         else if (*p == ProtocolRej)
 857         {
 858                 uint16_t proto = 0;
 859
 860                 if (l > 4)
 861                 {
 862                         proto = *(p+4);
 863                         if (l > 5 && !(proto & 1))
 864                         {
 865                                 proto <<= 8;
 866                                 proto |= *(p+5);
 867                         }
 868                 }
 869
 870                 if (proto == PPPIPV6CP)
 871                 {
 872                         LOG(3, s, t, "IPv6 rejected\n");
 873                         change_state(s, ipv6cp, Closed);
 874                 }
 875                 else
 876                 {
 877                         LOG(3, s, t, "LCP protocol reject: 0x%04X\n", proto);
 878                 }
 879         }
 880         else if (*p == EchoReq)
 881         {
 882                 *p = EchoReply;         // reply
 883                 *(uint32_t *) (p + 4) = htonl(session[s].magic); // our magic number
 884                 q = makeppp(b, sizeof(b), p, l, s, t, PPPLCP);
 885                 if (!q) return;
 886
 887                 LOG(4, s, t, "LCP: send %s\n", ppp_code(*q));
 888                 if (config->debug > 3) dumplcp(q, l);
 889
 890                 tunnelsend(b, l + (q - b), t); // send it
 891         }
 892         else if (*p == EchoReply)
 893         {
 894                 // Ignore it, last_packet time is set earlier than this.
 895         }
 896         else if (*p != CodeRej)
 897         {
 898                 ppp_code_rej(s, t, PPPLCP, "LCP", p, l, b, sizeof(b));
 899         }
 900 }
 901
 902 static void ipcp_open(sessionidt s, tunnelidt t)
 903 {
 904         LOG(3, s, t, "IPCP: Opened, session is now active\n");
 905
 906         change_state(s, ipcp, Opened);
 907
 908         if (!session[s].walled_garden)
 909         {
 910                 uint16_t r = radiusnew(s);
 911                 if (r)
 912                         radiussend(r, RADIUSSTART); // send radius start
 913         }
 914
 915         // start IPv6 if configured and still in passive state
 916         if (session[s].ppp.ipv6cp == Stopped)
 917         {
 918                 sendipv6cp(s, t);
 919                 change_state(s, ipv6cp, RequestSent);
 920         }
 921 }
 922
 923 // Process IPCP messages
 924 void processipcp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 925 {
 926         uint8_t b[MAXETHER];
 927         uint8_t *q = 0;
 928         uint16_t hl;
 929
 930         CSTAT(processipcp);
 931
 932         LOG_HEX(5, "IPCP", p, l);
 933         if (l < 5)
 934         {
 935                 LOG(1, s, t, "Short IPCP %d bytes\n", l);
 936                 STAT(tunnel_rx_errors);
 937                 return ;
 938         }
 939
 940         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
 941         {
 942                 LOG(1, s, t, "Length mismatch IPCP %u/%u\n", hl, l);
 943                 STAT(tunnel_rx_errors);
 944                 return ;
 945         }
 946         l = hl;
 947
 948         if (session[s].ppp.phase < Network)
 949         {
 950                 LOG(2, s, t, "IPCP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
 951                 return;
 952         }
 953
 954         LOG(3, s, t, "IPCP: recv %s\n", ppp_code(*p));
 955
 956         if (*p == ConfigAck)
 957         {
 958                 switch (session[s].ppp.ipcp)
 959                 {
 960                 case RequestSent:
 961                         initialise_restart_count(s, ipcp);
 962                         change_state(s, ipcp, AckReceived);
 963                         break;
 964
 965                 case AckReceived:
 966                 case Opened:
 967                         LOG(2, s, t, "IPCP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ipcp));
 968                         sendipcp(s, t);
 969                         change_state(s, ipcp, RequestSent);
 970                         break;
 971
 972                 case AckSent:
 973                         ipcp_open(s, t);
 974                         break;
 975
 976                 default:
 977                         LOG(2, s, t, "IPCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipcp));
 978                 }
 979         }
 980         else if (*p == ConfigReq)
 981         {
 982                 uint8_t *response = 0;
 983                 uint8_t *o = p + 4;
 984                 int length = l - 4;
 985                 int gotip = 0;
 986                 in_addr_t addr;
 987
 988                 while (length > 2)
 989                 {
 990                         switch (*o)
 991                         {
 992                         case 3: // ip address
 993                                 gotip++; // seen address
 994                                 if (o[1] != 6 || o[1] > length) return;
 995
 996                                 addr = htonl(session[s].ip);
 997                                 if (memcmp(o + 2, &addr, (sizeof addr)))
 998                                 {
 999                                         uint8_t *oq = q;
1000                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPCP, &response, q, p, o, (uint8_t *) &addr, sizeof(addr));
1001                                         if (!q || (q != oq && *response == ConfigRej))
1002                                         {
1003                                                 sessionshutdown(s, "Can't negotiate IPCP.", 3, 0);
1004                                                 return;
1005                                         }
1006                                 }
1007
1008                                 break;
1009
1010                         case 129: // primary DNS
1011                                 if (o[1] != 6 || o[1] > length) return;
1012
1013                                 addr = htonl(session[s].dns1);
1014                                 if (memcmp(o + 2, &addr, (sizeof addr)))
1015                                 {
1016                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPCP, &response, q, p, o, (uint8_t *) &addr, sizeof(addr));
1017                                         if (!q) return;
1018                                 }
1019
1020                                 break;
1021
1022                         case 131: // secondary 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                         default:
1035                                 LOG(2, s, t, "    Rejecting PPP IPCP Option type %d\n", *o);
1036                                 q = ppp_conf_rej(s, b, sizeof(b), PPPIPCP, &response, q, p, o);
1037                                 if (!q) return;
1038                         }
1039
1040                         length -= o[1];
1041                         o += o[1];
1042                 }
1043
1044                 if (response)
1045                 {
1046                         l = q - response; // IPCP packet length
1047                         *((uint16_t *) (response + 2)) = htons(l); // update header
1048                 }
1049                 else if (gotip)
1050                 {
1051                         // Send packet back as ConfigAck
1052                         response = makeppp(b, sizeof(b), p, l, s, t, PPPIPCP);
1053                         if (!response) return;
1054                         *response = ConfigAck;
1055                 }
1056                 else
1057                 {
1058                         LOG(1, s, t, "No IP in IPCP request\n");
1059                         STAT(tunnel_rx_errors);
1060                         return;
1061                 }
1062
1063                 switch (session[s].ppp.ipcp)
1064                 {
1065                 case Closed:
1066                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPIPCP);
1067                         if (!response) return;
1068                         *response = TerminateAck;
1069                         *((uint16_t *) (response + 2)) = htons(l = 4);
1070                         break;
1071
1072                 case Stopped:
1073                         initialise_restart_count(s, ipcp);
1074                         sendipcp(s, t);
1075                         if (*response == ConfigAck)
1076                                 change_state(s, ipcp, AckSent);
1077                         else
1078                                 change_state(s, ipcp, RequestSent);
1079
1080                         break;
1081
1082                 case RequestSent:
1083                         if (*response == ConfigAck)
1084                                 change_state(s, ipcp, AckSent);
1085
1086                         break;
1087
1088                 case AckReceived:
1089                         if (*response == ConfigAck)
1090                                 ipcp_open(s, t);
1091
1092                         break;
1093
1094                 case Opened:
1095                         initialise_restart_count(s, ipcp);
1096                         sendipcp(s, t);
1097                         /* fallthrough */
1098
1099                 case AckSent:
1100                         if (*response == ConfigAck)
1101                                 change_state(s, ipcp, AckSent);
1102                         else
1103                                 change_state(s, ipcp, RequestSent);
1104
1105                         break;
1106
1107                 default:
1108                         LOG(2, s, t, "IPCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipcp));
1109                         return;
1110                 }
1111
1112                 LOG(3, s, t, "IPCP: send %s\n", ppp_code(*response));
1113                 tunnelsend(b, l + (response - b), t);
1114         }
1115         else if (*p == TerminateReq)
1116         {
1117                 *p = TerminateAck;
1118                 q = makeppp(b, sizeof(b), p, l, s, t, PPPIPCP);
1119                 if (!q) return;
1120                 LOG(3, s, t, "IPCP: send %s\n", ppp_code(*q));
1121                 tunnelsend(b, l + (q - b), t);
1122                 change_state(s, ipcp, Stopped);
1123         }
1124         else if (*p != CodeRej)
1125         {
1126                 ppp_code_rej(s, t, PPPIPCP, "IPCP", p, l, b, sizeof(b));
1127         }
1128 }
1129
1130 static void ipv6cp_open(sessionidt s, tunnelidt t)
1131 {
1132         LOG(3, s, t, "IPV6CP: Opened\n");
1133
1134         change_state(s, ipv6cp, Opened);
1135         if (session[s].ipv6prefixlen)
1136                 route6set(s, session[s].ipv6route, session[s].ipv6prefixlen, 1);
1137
1138         // Send an initial RA (TODO: Should we send these regularly?)
1139         send_ipv6_ra(s, t, NULL);
1140 }
1141
1142 // Process IPV6CP messages
1143 void processipv6cp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1144 {
1145         uint8_t b[MAXETHER];
1146         uint8_t *q = 0;
1147         uint16_t hl;
1148
1149         CSTAT(processipv6cp);
1150
1151         LOG_HEX(5, "IPV6CP", p, l);
1152         if (l < 4)
1153         {
1154                 LOG(1, s, t, "Short IPV6CP %d bytes\n", l);
1155                 STAT(tunnel_rx_errors);
1156                 return ;
1157         }
1158
1159         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
1160         {
1161                 LOG(1, s, t, "Length mismatch IPV6CP %u/%u\n", hl, l);
1162                 STAT(tunnel_rx_errors);
1163                 return ;
1164         }
1165         l = hl;
1166
1167         if (session[s].ppp.phase < Network)
1168         {
1169                 LOG(2, s, t, "IPV6CP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
1170                 return;
1171         }
1172
1173         LOG(3, s, t, "IPV6CP: recv %s\n", ppp_code(*p));
1174
1175         if (!session[s].ip)
1176         {
1177                 LOG(3, s, t, "IPV6CP: no IPv4 address (IPCP in state %s)\n", ppp_state(session[s].ppp.ipcp));
1178                 return; // need IPCP to complete...
1179         }
1180
1181         if (*p == ConfigAck)
1182         {
1183                 switch (session[s].ppp.ipv6cp)
1184                 {
1185                 case RequestSent:
1186                         initialise_restart_count(s, ipv6cp);
1187                         change_state(s, ipv6cp, AckReceived);
1188                         break;
1189
1190                 case AckReceived:
1191                 case Opened:
1192                         LOG(2, s, t, "IPV6CP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ipv6cp));
1193                         sendipv6cp(s, t);
1194                         change_state(s, ipv6cp, RequestSent);
1195                         break;
1196
1197                 case AckSent:
1198                         ipv6cp_open(s, t);
1199                         break;
1200
1201                 default:
1202                         LOG(2, s, t, "IPV6CP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipv6cp));
1203                 }
1204         }
1205         else if (*p == ConfigReq)
1206         {
1207                 uint8_t *response = 0;
1208                 uint8_t *o = p + 4;
1209                 int length = l - 4;
1210                 int gotip = 0;
1211                 uint8_t ident[8];
1212
1213                 while (length > 2)
1214                 {
1215                         switch (*o)
1216                         {
1217                         case 1: // interface identifier
1218                                 gotip++; // seen address
1219                                 if (o[1] != 10 || o[1] > length) return;
1220
1221                                 *(uint32_t *) ident = htonl(session[s].ip);
1222                                 *(uint32_t *) (ident + 4) = 0;
1223
1224                                 if (memcmp(o + 2, ident, sizeof(ident)))
1225                                 {
1226                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPV6CP, &response, q, p, o, ident, sizeof(ident));
1227                                         if (!q) return;
1228                                 }
1229
1230                                 break;
1231
1232                         default:
1233                                 LOG(2, s, t, "    Rejecting PPP IPV6CP Option type %d\n", *o);
1234                                 q = ppp_conf_rej(s, b, sizeof(b), PPPIPV6CP, &response, q, p, o);
1235                                 if (!q) return;
1236                         }
1237
1238                         length -= o[1];
1239                         o += o[1];
1240                 }
1241
1242                 if (response)
1243                 {
1244                         l = q - response; // IPV6CP packet length
1245                         *((uint16_t *) (response + 2)) = htons(l); // update header
1246                 }
1247                 else if (gotip)
1248                 {
1249                         // Send packet back as ConfigAck
1250                         response = makeppp(b, sizeof(b), p, l, s, t, PPPIPV6CP);
1251                         if (!response) return;
1252                         *response = ConfigAck;
1253                 }
1254                 else
1255                 {
1256                         LOG(1, s, t, "No interface identifier in IPV6CP request\n");
1257                         STAT(tunnel_rx_errors);
1258                         return;
1259                 }
1260
1261                 switch (session[s].ppp.ipv6cp)
1262                 {
1263                 case Closed:
1264                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPIPV6CP);
1265                         if (!response) return;
1266                         *response = TerminateAck;
1267                         *((uint16_t *) (response + 2)) = htons(l = 4);
1268                         break;
1269
1270                 case Stopped:
1271                         initialise_restart_count(s, ipv6cp);
1272                         sendipv6cp(s, t);
1273                         if (*response == ConfigAck)
1274                                 change_state(s, ipv6cp, AckSent);
1275                         else
1276                                 change_state(s, ipv6cp, RequestSent);
1277
1278                         break;
1279
1280                 case RequestSent:
1281                         if (*response == ConfigAck)
1282                                 change_state(s, ipv6cp, AckSent);
1283
1284                         break;
1285
1286                 case AckReceived:
1287                         if (*response == ConfigAck)
1288                                 ipv6cp_open(s, t);
1289
1290                         break;
1291
1292                 case Opened:
1293                         initialise_restart_count(s, ipv6cp);
1294                         sendipv6cp(s, t);
1295                         /* fallthrough */
1296
1297                 case AckSent:
1298                         if (*response == ConfigAck)
1299                                 change_state(s, ipv6cp, AckSent);
1300                         else
1301                                 change_state(s, ipv6cp, RequestSent);
1302
1303                         break;
1304
1305                 default:
1306                         LOG(2, s, t, "IPV6CP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipv6cp));
1307                         return;
1308                 }
1309
1310                 LOG(3, s, t, "IPV6CP: send %s\n", ppp_code(*response));
1311                 tunnelsend(b, l + (response - b), t);
1312         }
1313         else if (*p == TerminateReq)
1314         {
1315                 *p = TerminateAck;
1316                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPIPV6CP);
1317                 if (!q) return;
1318                 LOG(3, s, t, "IPV6CP: send %s\n", ppp_code(*q));
1319                 tunnelsend(b, l + (q - b), t);
1320                 change_state(s, ipv6cp, Stopped);
1321         }
1322         else if (*p != CodeRej)
1323         {
1324                 ppp_code_rej(s, t, PPPIPV6CP, "IPV6CP", p, l, b, sizeof(b));
1325         }
1326 }
1327
1328 // process IP packet received
1329 //
1330 // This MUST be called with at least 4 byte behind 'p'.
1331 // (i.e. this routine writes to p[-4]).
1332 void processipin(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1333 {
1334         in_addr_t ip;
1335
1336         CSTAT(processipin);
1337
1338         LOG_HEX(5, "IP", p, l);
1339
1340         ip = ntohl(*(uint32_t *)(p + 12));
1341
1342         if (l > MAXETHER)
1343         {
1344                 LOG(1, s, t, "IP packet too long %d\n", l);
1345                 STAT(tunnel_rx_errors);
1346                 return ;
1347         }
1348
1349         if (session[s].ppp.phase != Network || session[s].ppp.ipcp != Opened)
1350                 return;
1351
1352         // no spoof (do sessionbyip to handled statically routed subnets)
1353         if (ip != session[s].ip && sessionbyip(htonl(ip)) != s)
1354         {
1355                 LOG(5, s, t, "Dropping packet with spoofed IP %s\n", fmtaddr(htonl(ip), 0));
1356                 return;
1357         }
1358
1359         // run access-list if any
1360         if (session[s].filter_in && !ip_filter(p, l, session[s].filter_in - 1))
1361                 return;
1362
1363         // Add on the tun header
1364         p -= 4;
1365         *(uint32_t *) p = htonl(PKTIP);
1366         l += 4;
1367
1368         // Are we throttled and a slave?
1369         if (session[s].tbf_in && !config->cluster_iam_master) {
1370                 // Pass it to the master for handling.
1371                 master_throttle_packet(session[s].tbf_in, p, l);
1372                 return;
1373         }
1374
1375         // Are we throttled and a master??
1376         if (session[s].tbf_in && config->cluster_iam_master) {
1377                 // Actually handle the throttled packets.
1378                 tbf_queue_packet(session[s].tbf_in, p, l);
1379                 return;
1380         }
1381
1382         // send to ethernet
1383         if (tun_write(p, l) < 0)
1384         {
1385                 STAT(tun_tx_errors);
1386                 LOG(0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1387                         l, strerror(errno), tunfd, p);
1388
1389                 return;
1390         }
1391
1392         p += 4;
1393         l -= 4;
1394
1395         if (session[s].snoop_ip && session[s].snoop_port)
1396         {
1397                 // Snooping this session
1398                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
1399         }
1400
1401         increment_counter(&session[s].cin, &session[s].cin_wrap, l);
1402         session[s].cin_delta += l;
1403         session[s].pin++;
1404
1405         sess_local[s].cin += l;
1406         sess_local[s].pin++;
1407
1408         eth_tx += l;
1409
1410         STAT(tun_tx_packets);
1411         INC_STAT(tun_tx_bytes, l);
1412 }
1413
1414 // process IPv6 packet received
1415 //
1416 // This MUST be called with at least 4 byte behind 'p'.
1417 // (i.e. this routine writes to p[-4]).
1418 void processipv6in(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1419 {
1420         struct in6_addr ip;
1421         in_addr_t ipv4;
1422
1423         CSTAT(processipv6in);
1424
1425         LOG_HEX(5, "IPv6", p, l);
1426
1427         ip = *(struct in6_addr *) (p + 8);
1428         ipv4 = ntohl(*(uint32_t *)(p + 16));
1429
1430         if (l > MAXETHER)
1431         {
1432                 LOG(1, s, t, "IP packet too long %d\n", l);
1433                 STAT(tunnel_rx_errors);
1434                 return ;
1435         }
1436
1437         if (session[s].ppp.phase != Network || session[s].ppp.ipv6cp != Opened)
1438                 return;
1439
1440         // no spoof
1441         if (ipv4 != session[s].ip && memcmp(&config->ipv6_prefix, &ip, 8) && sessionbyipv6(ip) != s)
1442         {
1443                 char str[INET6_ADDRSTRLEN];
1444                 LOG(5, s, t, "Dropping packet with spoofed IP %s\n",
1445                                 inet_ntop(AF_INET6, &ip, str, INET6_ADDRSTRLEN));
1446                 return;
1447         }
1448
1449         // Check if it's a Router Solicition message.
1450         if (*(p + 6) == 58 && *(p + 7) == 255 && *(p + 24) == 0xFF && *(p + 25) == 2 &&
1451                         *(uint32_t *)(p + 26) == 0 && *(uint32_t *)(p + 30) == 0 &&
1452                         *(uint32_t *)(p + 34) == 0 &&
1453                         *(p + 38) == 0 && *(p + 39) == 2 && *(p + 40) == 133) {
1454                 LOG(3, s, t, "Got IPv6 RS\n");
1455                 send_ipv6_ra(s, t, &ip);
1456                 return;
1457         }
1458
1459         // Add on the tun header
1460         p -= 4;
1461         *(uint32_t *) p = htonl(PKTIPV6);
1462         l += 4;
1463
1464         // Are we throttled and a slave?
1465         if (session[s].tbf_in && !config->cluster_iam_master) {
1466                 // Pass it to the master for handling.
1467                 master_throttle_packet(session[s].tbf_in, p, l);
1468                 return;
1469         }
1470
1471         // Are we throttled and a master??
1472         if (session[s].tbf_in && config->cluster_iam_master) {
1473                 // Actually handle the throttled packets.
1474                 tbf_queue_packet(session[s].tbf_in, p, l);
1475                 return;
1476         }
1477
1478         // send to ethernet
1479         if (tun_write(p, l) < 0)
1480         {
1481                 STAT(tun_tx_errors);
1482                 LOG(0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1483                         l, strerror(errno), tunfd, p);
1484
1485                 return;
1486         }
1487
1488         p += 4;
1489         l -= 4;
1490
1491         if (session[s].snoop_ip && session[s].snoop_port)
1492         {
1493                 // Snooping this session
1494                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
1495         }
1496
1497         increment_counter(&session[s].cin, &session[s].cin_wrap, l);
1498         session[s].cin_delta += l;
1499         session[s].pin++;
1500
1501         sess_local[s].cin += l;
1502         sess_local[s].pin++;
1503
1504         eth_tx += l;
1505
1506         STAT(tun_tx_packets);
1507         INC_STAT(tun_tx_bytes, l);
1508 }
1509
1510 //
1511 // Helper routine for the TBF filters.
1512 // Used to send queued data in from the user.
1513 //
1514 void send_ipin(sessionidt s, uint8_t *buf, int len)
1515 {
1516         LOG_HEX(5, "IP in throttled", buf, len);
1517
1518         if (write(tunfd, buf, len) < 0)
1519         {
1520                 STAT(tun_tx_errors);
1521                 LOG(0, 0, 0, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1522                         len, strerror(errno), tunfd, buf);
1523
1524                 return;
1525         }
1526
1527         buf += 4;
1528         len -= 4;
1529
1530         if (session[s].snoop_ip && session[s].snoop_port)
1531         {
1532                 // Snooping this session
1533                 snoop_send_packet(buf, len, session[s].snoop_ip, session[s].snoop_port);
1534         }
1535
1536         // Increment packet counters
1537         increment_counter(&session[s].cin, &session[s].cin_wrap, len);
1538         session[s].cin_delta += len;
1539         session[s].pin++;
1540
1541         sess_local[s].cin += len;
1542         sess_local[s].pin++;
1543
1544         eth_tx += len;
1545
1546         STAT(tun_tx_packets);
1547         INC_STAT(tun_tx_bytes, len - 4);
1548 }
1549
1550
1551 // Process CCP messages
1552 void processccp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1553 {
1554         uint8_t b[MAXETHER];
1555         uint8_t *q;
1556
1557         CSTAT(processccp);
1558
1559         LOG_HEX(5, "CCP", p, l);
1560
1561         if (session[s].ppp.phase < Network)
1562         {
1563                 LOG(2, s, t, "CCP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
1564                 return;
1565         }
1566
1567         if (l < 1)
1568         {
1569                 LOG(1, s, t, "Short CCP packet\n");
1570                 STAT(tunnel_rx_errors);
1571         }
1572
1573         LOG(3, s, t, "CCP: recv %s\n", ppp_code(*p));
1574         if (*p == ConfigAck)
1575         {
1576                 switch (session[s].ppp.ccp)
1577                 {
1578                 case RequestSent:
1579                         initialise_restart_count(s, ccp);
1580                         change_state(s, ccp, AckReceived);
1581                         break;
1582
1583                 case AckReceived:
1584                 case Opened:
1585                         LOG(2, s, t, "CCP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ccp));
1586                         sendccp(s, t);
1587                         change_state(s, ccp, RequestSent);
1588                         break;
1589
1590                 case AckSent:
1591                         LOG(3, s, t, "CCP: Opened\n");
1592                         change_state(s, ccp, Opened);
1593                         break;
1594
1595                 default:
1596                         LOG(2, s, t, "CCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ccp));
1597                 }
1598         }
1599         else if (*p == ConfigReq)
1600         {
1601                 if (l < 6) // accept no compression
1602                         *p = ConfigAck;
1603                 else // compression requested--reject
1604                         *p = ConfigRej;
1605
1606                 q = makeppp(b, sizeof(b), p, l, s, t, PPPCCP);
1607                 if (!q) return;
1608
1609                 switch (session[s].ppp.ccp)
1610                 {
1611                 case Closed:
1612                         q = makeppp(b, sizeof(b), p, 2, s, t, PPPCCP);
1613                         if (!q) return;
1614                         *q = TerminateAck;
1615                         *((uint16_t *) (q + 2)) = htons(l = 4);
1616                         break;
1617
1618                 case Stopped:
1619                         initialise_restart_count(s, ccp);
1620                         sendccp(s, t);
1621                         if (*q == ConfigAck)
1622                                 change_state(s, ccp, AckSent);
1623                         else
1624                                 change_state(s, ccp, RequestSent);
1625
1626                         break;
1627
1628                 case RequestSent:
1629                         if (*q == ConfigAck)
1630                                 change_state(s, ccp, AckSent);
1631
1632                         break;
1633
1634                 case AckReceived:
1635                         if (*q == ConfigAck)
1636                                 change_state(s, ccp, Opened);
1637
1638                         break;
1639
1640                 case Opened:
1641                         initialise_restart_count(s, ccp);
1642                         sendccp(s, t);
1643                         /* fallthrough */
1644
1645                 case AckSent:
1646                         if (*q == ConfigAck)
1647                                 change_state(s, ccp, AckSent);
1648                         else
1649                                 change_state(s, ccp, RequestSent);
1650
1651                         break;
1652
1653                 default:
1654                         LOG(2, s, t, "CCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ccp));
1655                         return;
1656                 }
1657
1658                 LOG(3, s, t, "CCP: send %s\n", ppp_code(*q));
1659                 tunnelsend(b, l + (q - b), t);
1660         }
1661         else if (*p == TerminateReq)
1662         {
1663                 *p = TerminateAck;
1664                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPCCP);
1665                 if (!q) return;
1666                 LOG(3, s, t, "CCP: send %s\n", ppp_code(*q));
1667                 tunnelsend(b, l + (q - b), t);
1668                 change_state(s, ccp, Stopped);
1669         }
1670         else if (*p != CodeRej)
1671         {
1672                 ppp_code_rej(s, t, PPPCCP, "CCP", p, l, b, sizeof(b));
1673         }
1674 }
1675
1676 // send a CHAP challenge
1677 void sendchap(sessionidt s, tunnelidt t)
1678 {
1679         uint8_t b[MAXETHER];
1680         uint16_t r;
1681         uint8_t *q;
1682
1683         CSTAT(sendchap);
1684
1685         r = radiusnew(s);
1686         if (!r)
1687         {
1688                 LOG(1, s, t, "No RADIUS to send challenge\n");
1689                 STAT(tunnel_tx_errors);
1690                 return;
1691         }
1692
1693         LOG(1, s, t, "Send CHAP challenge\n");
1694
1695         radius[r].chap = 1;             // CHAP not PAP
1696         radius[r].id++;
1697         if (radius[r].state != RADIUSCHAP)
1698                 radius[r].try = 0;
1699
1700         radius[r].state = RADIUSCHAP;
1701         radius[r].retry = backoff(radius[r].try++);
1702         if (radius[r].try > 5)
1703         {
1704                 sessionshutdown(s, "CHAP timeout.", 3, 0);
1705                 STAT(tunnel_tx_errors);
1706                 return ;
1707         }
1708         q = makeppp(b, sizeof(b), 0, 0, s, t, PPPCHAP);
1709         if (!q) return;
1710
1711         *q = 1;                                 // challenge
1712         q[1] = radius[r].id;                    // ID
1713         q[4] = 16;                              // value size (size of challenge)
1714         memcpy(q + 5, radius[r].auth, 16);      // challenge
1715         strcpy((char *) q + 21, hostname);      // our name
1716         *(uint16_t *) (q + 2) = htons(strlen(hostname) + 21); // length
1717         tunnelsend(b, strlen(hostname) + 21 + (q - b), t); // send it
1718 }
1719
1720 // fill in a L2TP message with a PPP frame,
1721 // copies existing PPP message and changes magic number if seen
1722 // returns start of PPP frame
1723 uint8_t *makeppp(uint8_t *b, int size, uint8_t *p, int l, sessionidt s, tunnelidt t, uint16_t mtype)
1724 {
1725         if (size < 12) // Need more space than this!!
1726         {
1727                 static int backtrace_count = 0;
1728                 LOG(0, s, t, "makeppp buffer too small for L2TP header (size=%d)\n", size);
1729                 log_backtrace(backtrace_count, 5)
1730                 return NULL;
1731         }
1732
1733         *(uint16_t *) (b + 0) = htons(0x0002); // L2TP with no options
1734         *(uint16_t *) (b + 2) = htons(tunnel[t].far); // tunnel
1735         *(uint16_t *) (b + 4) = htons(session[s].far); // session
1736         b += 6;
1737         if (mtype == PPPLCP || !(session[s].l2tp_flags & SESSIONACFC))
1738         {
1739                 *(uint16_t *) b = htons(0xFF03); // HDLC header
1740                 b += 2;
1741         }
1742         if (mtype < 0x100 && session[s].l2tp_flags & SESSIONPFC)
1743                 *b++ = mtype;
1744         else
1745         {
1746                 *(uint16_t *) b = htons(mtype);
1747                 b += 2;
1748         }
1749
1750         if (l + 12 > size)
1751         {
1752                 static int backtrace_count = 0;
1753                 LOG(2, s, t, "makeppp would overflow buffer (size=%d, header+payload=%d)\n", size, l + 12);
1754                 log_backtrace(backtrace_count, 5)
1755                 return NULL;
1756         }
1757
1758         if (p && l)
1759                 memcpy(b, p, l);
1760
1761         return b;
1762 }
1763
1764 static int add_lcp_auth(uint8_t *b, int size, int authtype)
1765 {
1766         int len = 0;
1767         if ((authtype == AUTHCHAP && size < 5) || size < 4)
1768                 return 0;
1769
1770         *b++ = 3; // Authentication-Protocol
1771         if (authtype == AUTHCHAP)
1772         {
1773                 len = *b++ = 5; // length
1774                 *(uint16_t *) b = htons(PPPCHAP); b += 2;
1775                 *b++ = 5; // MD5
1776         }
1777         else if (authtype == AUTHPAP)
1778         {
1779                 len = *b++ = 4; // length
1780                 *(uint16_t *) b = htons(PPPPAP); b += 2;
1781         }
1782         else
1783         {
1784                 LOG(0, 0, 0, "add_lcp_auth called with unsupported auth type %d\n", authtype);
1785         }
1786
1787         return len;
1788 }
1789
1790 // Send initial LCP ConfigReq for MRU, authentication type and magic no
1791 void sendlcp(sessionidt s, tunnelidt t)
1792 {
1793         uint8_t b[500], *q, *l;
1794         int authtype = sess_local[s].lcp_authtype;
1795
1796         if (!(q = makeppp(b, sizeof(b), NULL, 0, s, t, PPPLCP)))
1797                 return;
1798
1799         LOG(3, s, t, "LCP: send ConfigReq%s%s%s\n",
1800             authtype ? " (" : "",
1801             authtype ? (authtype == AUTHCHAP ? "CHAP" : "PAP") : "",
1802             authtype ? ")" : "");
1803
1804         l = q;
1805         *l++ = ConfigReq;
1806         *l++ = ++sess_local[s].lcp_ident; // ID
1807
1808         l += 2; //Save space for length
1809
1810         if (session[s].mru)
1811         {
1812                 *l++ = 1; *l++ = 4; // Maximum-Receive-Unit (length 4)
1813                 *(uint16_t *) l = htons(session[s].mru); l += 2;
1814         }
1815
1816         if (authtype)
1817                 l += add_lcp_auth(l, sizeof(b) - (l - b), authtype);
1818
1819         *l++ = 5; *l++ = 6; // Magic-Number (length 6)
1820         *(uint32_t *) l = htonl(session[s].magic);
1821         l += 4;
1822
1823         *(uint16_t *)(q + 2) = htons(l - q); // Length
1824
1825         LOG_HEX(5, "PPPLCP", q, l - q);
1826         if (config->debug > 3) dumplcp(q, l - q);
1827
1828         tunnelsend(b, (l - b), t);
1829 }
1830
1831 // Send CCP request for no compression
1832 void sendccp(sessionidt s, tunnelidt t)
1833 {
1834         uint8_t b[500], *q;
1835
1836         if (!(q = makeppp(b, sizeof(b), NULL, 0, s, t, PPPCCP)))
1837                 return;
1838
1839         LOG(3, s, t, "CCP: send ConfigReq (no compression)\n");
1840
1841         *q = ConfigReq;
1842         *(q + 1) = ++sess_local[s].lcp_ident; // ID
1843         *(uint16_t *)(q + 2) = htons(4); // Length
1844
1845         LOG_HEX(5, "PPPCCP", q, 4);
1846         tunnelsend(b, (q - b) + 4 , t);
1847 }