ppp.c

   1 // L2TPNS PPP Stuff
   2
   3 char const *cvs_id_ppp = "$Id: ppp.c,v 1.85 2005/11/04 14:41:50 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         if (mru > size) mru = size;
 453
 454         l += 4;
 455         if (l > mru) l = mru;
 456
 457         q = makeppp(buf, size, 0, 0, s, t, proto);
 458         if (!q) return;
 459
 460         *q = CodeRej;
 461         *(q + 1) = ++sess_local[s].lcp_ident;
 462         *(uint16_t *)(q + 2) = htons(l);
 463         memcpy(q + 4, p, l - 4);
 464
 465         LOG(2, s, t, "Unexpected %s code %s\n", pname, ppp_code(*p));
 466         LOG(3, s, t, "%s: send %s\n", pname, ppp_code(*q));
 467         if (config->debug > 3) dumplcp(q, l);
 468
 469         tunnelsend(buf, l + (q - buf), t);
 470 }
 471
 472 // Process LCP messages
 473 void processlcp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 474 {
 475         uint8_t b[MAXETHER];
 476         uint8_t *q = NULL;
 477         uint32_t magicno = 0;
 478         uint16_t hl;
 479
 480         CSTAT(processlcp);
 481
 482         LOG_HEX(5, "LCP", p, l);
 483         if (l < 4)
 484         {
 485                 LOG(1, s, t, "Short LCP %d bytes\n", l);
 486                 STAT(tunnel_rx_errors);
 487                 return ;
 488         }
 489
 490         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
 491         {
 492                 LOG(1, s, t, "Length mismatch LCP %u/%u\n", hl, l);
 493                 STAT(tunnel_rx_errors);
 494                 return ;
 495         }
 496         l = hl;
 497
 498         if (session[s].die) // going down...
 499                 return;
 500
 501         LOG(*p == EchoReq ? 4 : 3, s, t, "LCP: recv %s\n", ppp_code(*p));
 502         if (config->debug > 3) dumplcp(p, l);
 503
 504         if (*p == ConfigAck)
 505         {
 506                 int x = l - 4;
 507                 uint8_t *o = (p + 4);
 508                 int authtype = 0;
 509
 510                 while (x > 2)
 511                 {
 512                         int type = o[0];
 513                         int length = o[1];
 514
 515                         if (length == 0 || type == 0 || x < length) break;
 516                         switch (type)
 517                         {
 518                                 case 3: // Authentication-Protocol
 519                                         {
 520                                                 int proto = ntohs(*(uint16_t *)(o + 2));
 521                                                 if (proto == PPPPAP)
 522                                                         authtype = AUTHPAP;
 523                                                 else if (proto == PPPCHAP && *(o + 4) == 5)
 524                                                         authtype = AUTHCHAP;
 525                                         }
 526
 527                                         break;
 528                         }
 529                         x -= length;
 530                         o += length;
 531                 }
 532
 533                 if (!session[s].ip && authtype)
 534                         sess_local[s].lcp_authtype = authtype;
 535
 536                 switch (session[s].ppp.lcp)
 537                 {
 538                 case RequestSent:
 539                         initialise_restart_count(s, lcp);
 540                         change_state(s, lcp, AckReceived);
 541                         break;
 542
 543                 case AckReceived:
 544                 case Opened:
 545                         LOG(2, s, t, "LCP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.lcp));
 546                         if (session[s].ppp.lcp == Opened)
 547                                 lcp_restart(s);
 548
 549                         sendlcp(s, t);
 550                         change_state(s, lcp, RequestSent);
 551                         break;
 552
 553                 case AckSent:
 554                         lcp_open(s, t);
 555                         break;
 556
 557                 default:
 558                         LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp));
 559                 }
 560         }
 561         else if (*p == ConfigReq)
 562         {
 563                 int x = l - 4;
 564                 uint8_t *o = (p + 4);
 565                 uint8_t *response = 0;
 566                 static uint8_t asyncmap[4] = { 0, 0, 0, 0 }; // all zero
 567                 static uint8_t authproto[5];
 568
 569                 while (x > 2)
 570                 {
 571                         int type = o[0];
 572                         int length = o[1];
 573
 574                         if (length == 0 || type == 0 || x < length) break;
 575                         switch (type)
 576                         {
 577                                 case 1: // Maximum-Receive-Unit
 578                                         session[s].mru = ntohs(*(uint16_t *)(o + 2));
 579                                         break;
 580
 581                                 case 2: // Async-Control-Character-Map
 582                                         if (!ntohl(*(uint32_t *)(o + 2))) // all bits zero is OK
 583                                                 break;
 584
 585                                         LOG(3, s, t, "    Remote requesting asyncmap.  Rejecting.\n");
 586                                         q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, asyncmap, sizeof(asyncmap));
 587                                         break;
 588
 589                                 case 3: // Authentication-Protocol
 590                                         {
 591                                                 int proto = ntohs(*(uint16_t *)(o + 2));
 592                                                 char proto_name[] = "0x0000";
 593                                                 int alen;
 594
 595                                                 if (proto == PPPPAP)
 596                                                 {
 597                                                         if (config->radius_authtypes & AUTHPAP)
 598                                                         {
 599                                                                 sess_local[s].lcp_authtype = AUTHPAP;
 600                                                                 break;
 601                                                         }
 602
 603                                                         strcpy(proto_name, "PAP");
 604                                                 }
 605                                                 else if (proto == PPPCHAP)
 606                                                 {
 607                                                         if (config->radius_authtypes & AUTHCHAP
 608                                                             && *(o + 4) == 5) // MD5
 609                                                         {
 610                                                                 sess_local[s].lcp_authtype = AUTHCHAP;
 611                                                                 break;
 612                                                         }
 613
 614                                                         strcpy(proto_name, "CHAP");
 615                                                 }
 616                                                 else
 617                                                         sprintf(proto_name, "%#4.4x", proto);
 618
 619                                                 LOG(3, s, t, "    Remote requesting %s authentication.  Rejecting.\n", proto_name);
 620
 621                                                 alen = add_lcp_auth(authproto, sizeof(authproto), config->radius_authprefer);
 622                                                 if (alen < 2) break; // paranoia
 623
 624                                                 q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, authproto + 2, alen - 2);
 625                                                 if (q && *response == ConfigNak &&
 626                                                         config->radius_authtypes != config->radius_authprefer)
 627                                                 {
 628                                                         // alternate type
 629                                                         alen = add_lcp_auth(authproto, sizeof(authproto), config->radius_authtypes & ~config->radius_authprefer);
 630                                                         if (alen < 2) break;
 631                                                         q = ppp_conf_nak(s, b, sizeof(b), PPPLCP, &response, q, p, o, authproto + 2, alen - 2);
 632                                                 }
 633
 634                                                 break;
 635                                         }
 636                                         break;
 637
 638                                 case 5: // Magic-Number
 639                                         magicno = ntohl(*(uint32_t *)(o + 2));
 640                                         break;
 641
 642                                 case 4: // Quality-Protocol
 643                                 case 7: // Protocol-Field-Compression
 644                                 case 8: // Address-And-Control-Field-Compression
 645                                         break;
 646
 647                                 default: // Reject any unknown options
 648                                         LOG(3, s, t, "    Rejecting unknown PPP LCP option %d\n", type);
 649                                         q = ppp_conf_rej(s, b, sizeof(b), PPPLCP, &response, q, p, o);
 650                         }
 651                         x -= length;
 652                         o += length;
 653                 }
 654
 655                 if (response)
 656                 {
 657                         l = q - response; // LCP packet length
 658                         *((uint16_t *) (response + 2)) = htons(l); // update header
 659                 }
 660                 else
 661                 {
 662                         // Send packet back as ConfigAck
 663                         response = makeppp(b, sizeof(b), p, l, s, t, PPPLCP);
 664                         if (!response) return;
 665                         *response = ConfigAck;
 666                 }
 667
 668                 switch (session[s].ppp.lcp)
 669                 {
 670                 case Closed:
 671                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPLCP);
 672                         if (!response) return;
 673                         *response = TerminateAck;
 674                         *((uint16_t *) (response + 2)) = htons(l = 4);
 675                         break;
 676
 677                 case Stopped:
 678                         initialise_restart_count(s, lcp);
 679                         sendlcp(s, t);
 680                         if (*response == ConfigAck)
 681                                 change_state(s, lcp, AckSent);
 682                         else
 683                                 change_state(s, lcp, RequestSent);
 684
 685                         break;
 686
 687                 case RequestSent:
 688                         if (*response == ConfigAck)
 689                                 change_state(s, lcp, AckSent);
 690
 691                         break;
 692
 693                 case AckReceived:
 694                         if (*response == ConfigAck)
 695                                 lcp_open(s, t);
 696
 697                         break;
 698
 699                 case Opened:
 700                         lcp_restart(s);
 701                         sendlcp(s, t);
 702                         /* fallthrough */
 703
 704                 case AckSent:
 705                         if (*response == ConfigAck)
 706                                 change_state(s, lcp, AckSent);
 707                         else
 708                                 change_state(s, lcp, RequestSent);
 709
 710                         break;
 711
 712                 default:
 713                         LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp));
 714                         return;
 715                 }
 716
 717                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*response));
 718                 if (config->debug > 3) dumplcp(response, l);
 719
 720                 tunnelsend(b, l + (response - b), t);
 721         }
 722         else if (*p == ConfigNak || *p == ConfigRej)
 723         {
 724                 int x = l - 4;
 725                 uint8_t *o = (p + 4);
 726                 int authtype = -1;
 727
 728                 while (x > 2)
 729                 {
 730                         int type = o[0];
 731                         int length = o[1];
 732
 733                         if (length == 0 || type == 0 || x < length) break;
 734                         switch (type)
 735                         {
 736                                 case 1: // Maximum-Receive-Unit
 737                                         if (*p == ConfigNak)
 738                                         {
 739                                                 sess_local[s].ppp_mru = ntohs(*(uint16_t *)(o + 2));
 740                                                 LOG(3, s, t, "    Remote requested MRU of %u\n", sess_local[s].ppp_mru);
 741                                         }
 742                                         else
 743                                         {
 744                                                 sess_local[s].ppp_mru = 0;
 745                                                 LOG(3, s, t, "    Remote rejected MRU negotiation\n");
 746                                         }
 747
 748                                         break;
 749
 750                                 case 3: // Authentication-Protocol
 751                                         if (authtype > 0)
 752                                                 break;
 753
 754                                         if (*p == ConfigNak)
 755                                         {
 756                                                 int proto = ntohs(*(uint16_t *)(o + 2));
 757                                                 if (proto == PPPPAP)
 758                                                 {
 759                                                         authtype = config->radius_authtypes & AUTHPAP;
 760                                                         LOG(3, s, t, "    Remote requested PAP authentication...%sing\n",
 761                                                                 authtype ? "accept" : "reject");
 762                                                 }
 763                                                 else if (proto == PPPCHAP && *(o + 4) == 5)
 764                                                 {
 765                                                         authtype = config->radius_authtypes & AUTHCHAP;
 766                                                         LOG(3, s, t, "    Remote requested CHAP authentication...%sing\n",
 767                                                                 authtype ? "accept" : "reject");
 768                                                 }
 769                                                 else
 770                                                 {
 771                                                         LOG(3, s, t, "    Rejecting unsupported authentication %#4x\n",
 772                                                                 proto);
 773                                                 }
 774                                         }
 775                                         else
 776                                         {
 777                                                 LOG(2, s, t, "LCP: remote rejected auth negotiation\n");
 778                                                 authtype = 0; // shutdown
 779                                         }
 780
 781                                         break;
 782
 783                                 default:
 784                                         LOG(2, s, t, "LCP: remote sent %s for type %u?\n", ppp_code(*p), type);
 785                                         break;
 786                         }
 787                         x -= length;
 788                         o += length;
 789                 }
 790
 791                 if (!authtype)
 792                 {
 793                         sessionshutdown(s, "Unsupported authentication.", 3, 0);
 794                         return;
 795                 }
 796
 797                 if (authtype > 0)
 798                         sess_local[s].lcp_authtype = authtype;
 799
 800                 switch (session[s].ppp.lcp)
 801                 {
 802                 case Closed:
 803                 case Stopped:
 804                         {
 805                                 uint8_t *response = makeppp(b, sizeof(b), p, 2, s, t, PPPLCP);
 806                                 if (!response) return;
 807                                 *response = TerminateAck;
 808                                 *((uint16_t *) (response + 2)) = htons(l = 4);
 809
 810                                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*response));
 811                                 if (config->debug > 3) dumplcp(response, l);
 812
 813                                 tunnelsend(b, l + (response - b), t);
 814                         }
 815                         break;
 816
 817                 case RequestSent:
 818                 case AckSent:
 819                         initialise_restart_count(s, lcp);
 820                         sendlcp(s, t);
 821                         break;
 822
 823                 case AckReceived:
 824                         LOG(2, s, t, "LCP: ConfigNak in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.lcp));
 825                         sendlcp(s, t);
 826                         break;
 827
 828                 case Opened:
 829                         lcp_restart(s);
 830                         sendlcp(s, t);
 831                         break;
 832
 833                 default:
 834                         LOG(2, s, t, "LCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.lcp));
 835                         return;
 836                 }
 837         }
 838         else if (*p == TerminateReq)
 839         {
 840                 *p = TerminateAck;      // close
 841                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPLCP);
 842                 if (!q) return;
 843
 844                 LOG(3, s, t, "LCP: send %s\n", ppp_code(*q));
 845                 if (config->debug > 3) dumplcp(q, l);
 846
 847                 tunnelsend(b, l + (q - b), t); // send it
 848                 sessionshutdown(s, "Remote end closed connection.", 3, 0);
 849         }
 850         else if (*p == TerminateAck)
 851         {
 852                 sessionshutdown(s, "Connection closed.", 3, 0);
 853         }
 854         else if (*p == ProtocolRej)
 855         {
 856                 uint16_t proto = 0;
 857
 858                 if (l > 4)
 859                 {
 860                         proto = *(p+4);
 861                         if (l > 5 && !(proto & 1))
 862                         {
 863                                 proto <<= 8;
 864                                 proto |= *(p+5);
 865                         }
 866                 }
 867
 868                 if (proto == PPPIPV6CP)
 869                 {
 870                         LOG(3, s, t, "IPv6 rejected\n");
 871                         change_state(s, ipv6cp, Closed);
 872                 }
 873                 else
 874                 {
 875                         LOG(3, s, t, "LCP protocol reject: 0x%04X\n", proto);
 876                 }
 877         }
 878         else if (*p == EchoReq)
 879         {
 880                 *p = EchoReply;         // reply
 881                 *(uint32_t *) (p + 4) = htonl(session[s].magic); // our magic number
 882                 q = makeppp(b, sizeof(b), p, l, s, t, PPPLCP);
 883                 if (!q) return;
 884
 885                 LOG(4, s, t, "LCP: send %s\n", ppp_code(*q));
 886                 if (config->debug > 3) dumplcp(q, l);
 887
 888                 tunnelsend(b, l + (q - b), t); // send it
 889         }
 890         else if (*p == EchoReply)
 891         {
 892                 // Ignore it, last_packet time is set earlier than this.
 893         }
 894         else if (*p != CodeRej)
 895         {
 896                 ppp_code_rej(s, t, PPPLCP, "LCP", p, l, b, sizeof(b));
 897         }
 898 }
 899
 900 static void ipcp_open(sessionidt s, tunnelidt t)
 901 {
 902         LOG(3, s, t, "IPCP: Opened, session is now active\n");
 903
 904         change_state(s, ipcp, Opened);
 905
 906         if (!(session[s].walled_garden || session[s].flags & SESSION_STARTED))
 907         {
 908                 uint16_t r = radiusnew(s);
 909                 if (r)
 910                 {
 911                         radiussend(r, RADIUSSTART); // send radius start
 912
 913                         // don't send further Start records if IPCP is restarted
 914                         session[s].flags |= SESSION_STARTED;
 915                         cluster_send_session(s);
 916                 }
 917         }
 918
 919         // start IPv6 if configured and still in passive state
 920         if (session[s].ppp.ipv6cp == Stopped)
 921         {
 922                 sendipv6cp(s, t);
 923                 change_state(s, ipv6cp, RequestSent);
 924         }
 925 }
 926
 927 // Process IPCP messages
 928 void processipcp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 929 {
 930         uint8_t b[MAXETHER];
 931         uint8_t *q = 0;
 932         uint16_t hl;
 933
 934         CSTAT(processipcp);
 935
 936         LOG_HEX(5, "IPCP", p, l);
 937         if (l < 5)
 938         {
 939                 LOG(1, s, t, "Short IPCP %d bytes\n", l);
 940                 STAT(tunnel_rx_errors);
 941                 return ;
 942         }
 943
 944         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
 945         {
 946                 LOG(1, s, t, "Length mismatch IPCP %u/%u\n", hl, l);
 947                 STAT(tunnel_rx_errors);
 948                 return ;
 949         }
 950         l = hl;
 951
 952         if (session[s].ppp.phase < Network)
 953         {
 954                 LOG(2, s, t, "IPCP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
 955                 return;
 956         }
 957
 958         LOG(3, s, t, "IPCP: recv %s\n", ppp_code(*p));
 959
 960         if (*p == ConfigAck)
 961         {
 962                 switch (session[s].ppp.ipcp)
 963                 {
 964                 case RequestSent:
 965                         initialise_restart_count(s, ipcp);
 966                         change_state(s, ipcp, AckReceived);
 967                         break;
 968
 969                 case AckReceived:
 970                 case Opened:
 971                         LOG(2, s, t, "IPCP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ipcp));
 972                         sendipcp(s, t);
 973                         change_state(s, ipcp, RequestSent);
 974                         break;
 975
 976                 case AckSent:
 977                         ipcp_open(s, t);
 978                         break;
 979
 980                 default:
 981                         LOG(2, s, t, "IPCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipcp));
 982                 }
 983         }
 984         else if (*p == ConfigReq)
 985         {
 986                 uint8_t *response = 0;
 987                 uint8_t *o = p + 4;
 988                 int length = l - 4;
 989                 int gotip = 0;
 990                 in_addr_t addr;
 991
 992                 while (length > 2)
 993                 {
 994                         switch (*o)
 995                         {
 996                         case 3: // ip address
 997                                 gotip++; // seen address
 998                                 if (o[1] != 6 || o[1] > length) return;
 999
1000                                 addr = htonl(session[s].ip);
1001                                 if (memcmp(o + 2, &addr, (sizeof addr)))
1002                                 {
1003                                         uint8_t *oq = q;
1004                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPCP, &response, q, p, o, (uint8_t *) &addr, sizeof(addr));
1005                                         if (!q || (q != oq && *response == ConfigRej))
1006                                         {
1007                                                 sessionshutdown(s, "Can't negotiate IPCP.", 3, 0);
1008                                                 return;
1009                                         }
1010                                 }
1011
1012                                 break;
1013
1014                         case 129: // primary DNS
1015                                 if (o[1] != 6 || o[1] > length) return;
1016
1017                                 addr = htonl(session[s].dns1);
1018                                 if (memcmp(o + 2, &addr, (sizeof addr)))
1019                                 {
1020                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPCP, &response, q, p, o, (uint8_t *) &addr, sizeof(addr));
1021                                         if (!q) return;
1022                                 }
1023
1024                                 break;
1025
1026                         case 131: // secondary DNS
1027                                 if (o[1] != 6 || o[1] > length) return;
1028
1029                                 addr = htonl(session[s].dns1);
1030                                 if (memcmp(o + 2, &addr, sizeof(addr)))
1031                                 {
1032                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPCP, &response, q, p, o, (uint8_t *) &addr, sizeof(addr));
1033                                         if (!q) return;
1034                                 }
1035
1036                                 break;
1037
1038                         default:
1039                                 LOG(2, s, t, "    Rejecting PPP IPCP Option type %d\n", *o);
1040                                 q = ppp_conf_rej(s, b, sizeof(b), PPPIPCP, &response, q, p, o);
1041                                 if (!q) return;
1042                         }
1043
1044                         length -= o[1];
1045                         o += o[1];
1046                 }
1047
1048                 if (response)
1049                 {
1050                         l = q - response; // IPCP packet length
1051                         *((uint16_t *) (response + 2)) = htons(l); // update header
1052                 }
1053                 else if (gotip)
1054                 {
1055                         // Send packet back as ConfigAck
1056                         response = makeppp(b, sizeof(b), p, l, s, t, PPPIPCP);
1057                         if (!response) return;
1058                         *response = ConfigAck;
1059                 }
1060                 else
1061                 {
1062                         LOG(1, s, t, "No IP in IPCP request\n");
1063                         STAT(tunnel_rx_errors);
1064                         return;
1065                 }
1066
1067                 switch (session[s].ppp.ipcp)
1068                 {
1069                 case Closed:
1070                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPIPCP);
1071                         if (!response) return;
1072                         *response = TerminateAck;
1073                         *((uint16_t *) (response + 2)) = htons(l = 4);
1074                         break;
1075
1076                 case Stopped:
1077                         initialise_restart_count(s, ipcp);
1078                         sendipcp(s, t);
1079                         if (*response == ConfigAck)
1080                                 change_state(s, ipcp, AckSent);
1081                         else
1082                                 change_state(s, ipcp, RequestSent);
1083
1084                         break;
1085
1086                 case RequestSent:
1087                         if (*response == ConfigAck)
1088                                 change_state(s, ipcp, AckSent);
1089
1090                         break;
1091
1092                 case AckReceived:
1093                         if (*response == ConfigAck)
1094                                 ipcp_open(s, t);
1095
1096                         break;
1097
1098                 case Opened:
1099                         initialise_restart_count(s, ipcp);
1100                         sendipcp(s, t);
1101                         /* fallthrough */
1102
1103                 case AckSent:
1104                         if (*response == ConfigAck)
1105                                 change_state(s, ipcp, AckSent);
1106                         else
1107                                 change_state(s, ipcp, RequestSent);
1108
1109                         break;
1110
1111                 default:
1112                         LOG(2, s, t, "IPCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipcp));
1113                         return;
1114                 }
1115
1116                 LOG(3, s, t, "IPCP: send %s\n", ppp_code(*response));
1117                 tunnelsend(b, l + (response - b), t);
1118         }
1119         else if (*p == TerminateReq)
1120         {
1121                 *p = TerminateAck;
1122                 q = makeppp(b, sizeof(b), p, l, s, t, PPPIPCP);
1123                 if (!q) return;
1124                 LOG(3, s, t, "IPCP: send %s\n", ppp_code(*q));
1125                 tunnelsend(b, l + (q - b), t);
1126                 change_state(s, ipcp, Stopped);
1127         }
1128         else if (*p != CodeRej)
1129         {
1130                 ppp_code_rej(s, t, PPPIPCP, "IPCP", p, l, b, sizeof(b));
1131         }
1132 }
1133
1134 static void ipv6cp_open(sessionidt s, tunnelidt t)
1135 {
1136         LOG(3, s, t, "IPV6CP: Opened\n");
1137
1138         change_state(s, ipv6cp, Opened);
1139         if (session[s].ipv6prefixlen)
1140                 route6set(s, session[s].ipv6route, session[s].ipv6prefixlen, 1);
1141
1142         // Send an initial RA (TODO: Should we send these regularly?)
1143         send_ipv6_ra(s, t, NULL);
1144 }
1145
1146 // Process IPV6CP messages
1147 void processipv6cp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1148 {
1149         uint8_t b[MAXETHER];
1150         uint8_t *q = 0;
1151         uint16_t hl;
1152
1153         CSTAT(processipv6cp);
1154
1155         LOG_HEX(5, "IPV6CP", p, l);
1156         if (l < 4)
1157         {
1158                 LOG(1, s, t, "Short IPV6CP %d bytes\n", l);
1159                 STAT(tunnel_rx_errors);
1160                 return ;
1161         }
1162
1163         if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
1164         {
1165                 LOG(1, s, t, "Length mismatch IPV6CP %u/%u\n", hl, l);
1166                 STAT(tunnel_rx_errors);
1167                 return ;
1168         }
1169         l = hl;
1170
1171         if (session[s].ppp.phase < Network)
1172         {
1173                 LOG(2, s, t, "IPV6CP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
1174                 return;
1175         }
1176
1177         LOG(3, s, t, "IPV6CP: recv %s\n", ppp_code(*p));
1178
1179         if (!session[s].ip)
1180         {
1181                 LOG(3, s, t, "IPV6CP: no IPv4 address (IPCP in state %s)\n", ppp_state(session[s].ppp.ipcp));
1182                 return; // need IPCP to complete...
1183         }
1184
1185         if (*p == ConfigAck)
1186         {
1187                 switch (session[s].ppp.ipv6cp)
1188                 {
1189                 case RequestSent:
1190                         initialise_restart_count(s, ipv6cp);
1191                         change_state(s, ipv6cp, AckReceived);
1192                         break;
1193
1194                 case AckReceived:
1195                 case Opened:
1196                         LOG(2, s, t, "IPV6CP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ipv6cp));
1197                         sendipv6cp(s, t);
1198                         change_state(s, ipv6cp, RequestSent);
1199                         break;
1200
1201                 case AckSent:
1202                         ipv6cp_open(s, t);
1203                         break;
1204
1205                 default:
1206                         LOG(2, s, t, "IPV6CP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipv6cp));
1207                 }
1208         }
1209         else if (*p == ConfigReq)
1210         {
1211                 uint8_t *response = 0;
1212                 uint8_t *o = p + 4;
1213                 int length = l - 4;
1214                 int gotip = 0;
1215                 uint8_t ident[8];
1216
1217                 while (length > 2)
1218                 {
1219                         switch (*o)
1220                         {
1221                         case 1: // interface identifier
1222                                 gotip++; // seen address
1223                                 if (o[1] != 10 || o[1] > length) return;
1224
1225                                 *(uint32_t *) ident = htonl(session[s].ip);
1226                                 *(uint32_t *) (ident + 4) = 0;
1227
1228                                 if (memcmp(o + 2, ident, sizeof(ident)))
1229                                 {
1230                                         q = ppp_conf_nak(s, b, sizeof(b), PPPIPV6CP, &response, q, p, o, ident, sizeof(ident));
1231                                         if (!q) return;
1232                                 }
1233
1234                                 break;
1235
1236                         default:
1237                                 LOG(2, s, t, "    Rejecting PPP IPV6CP Option type %d\n", *o);
1238                                 q = ppp_conf_rej(s, b, sizeof(b), PPPIPV6CP, &response, q, p, o);
1239                                 if (!q) return;
1240                         }
1241
1242                         length -= o[1];
1243                         o += o[1];
1244                 }
1245
1246                 if (response)
1247                 {
1248                         l = q - response; // IPV6CP packet length
1249                         *((uint16_t *) (response + 2)) = htons(l); // update header
1250                 }
1251                 else if (gotip)
1252                 {
1253                         // Send packet back as ConfigAck
1254                         response = makeppp(b, sizeof(b), p, l, s, t, PPPIPV6CP);
1255                         if (!response) return;
1256                         *response = ConfigAck;
1257                 }
1258                 else
1259                 {
1260                         LOG(1, s, t, "No interface identifier in IPV6CP request\n");
1261                         STAT(tunnel_rx_errors);
1262                         return;
1263                 }
1264
1265                 switch (session[s].ppp.ipv6cp)
1266                 {
1267                 case Closed:
1268                         response = makeppp(b, sizeof(b), p, 2, s, t, PPPIPV6CP);
1269                         if (!response) return;
1270                         *response = TerminateAck;
1271                         *((uint16_t *) (response + 2)) = htons(l = 4);
1272                         break;
1273
1274                 case Stopped:
1275                         initialise_restart_count(s, ipv6cp);
1276                         sendipv6cp(s, t);
1277                         if (*response == ConfigAck)
1278                                 change_state(s, ipv6cp, AckSent);
1279                         else
1280                                 change_state(s, ipv6cp, RequestSent);
1281
1282                         break;
1283
1284                 case RequestSent:
1285                         if (*response == ConfigAck)
1286                                 change_state(s, ipv6cp, AckSent);
1287
1288                         break;
1289
1290                 case AckReceived:
1291                         if (*response == ConfigAck)
1292                                 ipv6cp_open(s, t);
1293
1294                         break;
1295
1296                 case Opened:
1297                         initialise_restart_count(s, ipv6cp);
1298                         sendipv6cp(s, t);
1299                         /* fallthrough */
1300
1301                 case AckSent:
1302                         if (*response == ConfigAck)
1303                                 change_state(s, ipv6cp, AckSent);
1304                         else
1305                                 change_state(s, ipv6cp, RequestSent);
1306
1307                         break;
1308
1309                 default:
1310                         LOG(2, s, t, "IPV6CP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ipv6cp));
1311                         return;
1312                 }
1313
1314                 LOG(3, s, t, "IPV6CP: send %s\n", ppp_code(*response));
1315                 tunnelsend(b, l + (response - b), t);
1316         }
1317         else if (*p == TerminateReq)
1318         {
1319                 *p = TerminateAck;
1320                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPIPV6CP);
1321                 if (!q) return;
1322                 LOG(3, s, t, "IPV6CP: send %s\n", ppp_code(*q));
1323                 tunnelsend(b, l + (q - b), t);
1324                 change_state(s, ipv6cp, Stopped);
1325         }
1326         else if (*p != CodeRej)
1327         {
1328                 ppp_code_rej(s, t, PPPIPV6CP, "IPV6CP", p, l, b, sizeof(b));
1329         }
1330 }
1331
1332 // process IP packet received
1333 //
1334 // This MUST be called with at least 4 byte behind 'p'.
1335 // (i.e. this routine writes to p[-4]).
1336 void processipin(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1337 {
1338         in_addr_t ip;
1339
1340         CSTAT(processipin);
1341
1342         LOG_HEX(5, "IP", p, l);
1343
1344         if (l < 20)
1345         {
1346                 LOG(1, s, t, "IP packet too short %d\n", l);
1347                 STAT(tunnel_rx_errors);
1348                 return ;
1349         }
1350
1351         ip = ntohl(*(uint32_t *)(p + 12));
1352
1353         if (l > MAXETHER)
1354         {
1355                 LOG(1, s, t, "IP packet too long %d\n", l);
1356                 STAT(tunnel_rx_errors);
1357                 return ;
1358         }
1359
1360         if (session[s].ppp.phase != Network || session[s].ppp.ipcp != Opened)
1361                 return;
1362
1363         // no spoof (do sessionbyip to handled statically routed subnets)
1364         if (ip != session[s].ip && sessionbyip(htonl(ip)) != s)
1365         {
1366                 LOG(5, s, t, "Dropping packet with spoofed IP %s\n", fmtaddr(htonl(ip), 0));
1367                 return;
1368         }
1369
1370         // run access-list if any
1371         if (session[s].filter_in && !ip_filter(p, l, session[s].filter_in - 1))
1372                 return;
1373
1374         // adjust MSS on SYN and SYN,ACK packets with options
1375         if ((ntohs(*(uint16_t *) (p + 6)) & 0x1fff) == 0 && p[9] == IPPROTO_TCP) // first tcp fragment
1376         {
1377                 int ihl = (p[0] & 0xf) * 4; // length of IP header
1378                 if (l >= ihl + 20 && (p[ihl + 13] & TCP_FLAG_SYN) && ((p[ihl + 12] >> 4) > 5))
1379                         adjust_tcp_mss(s, t, p, l, p + ihl);
1380         }
1381
1382         // Add on the tun header
1383         p -= 4;
1384         *(uint32_t *) p = htonl(PKTIP);
1385         l += 4;
1386
1387         // Are we throttled and a slave?
1388         if (session[s].tbf_in && !config->cluster_iam_master) {
1389                 // Pass it to the master for handling.
1390                 master_throttle_packet(session[s].tbf_in, p, l);
1391                 return;
1392         }
1393
1394         // Are we throttled and a master??
1395         if (session[s].tbf_in && config->cluster_iam_master) {
1396                 // Actually handle the throttled packets.
1397                 tbf_queue_packet(session[s].tbf_in, p, l);
1398                 return;
1399         }
1400
1401         // send to ethernet
1402         if (tun_write(p, l) < 0)
1403         {
1404                 STAT(tun_tx_errors);
1405                 LOG(0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1406                         l, strerror(errno), tunfd, p);
1407
1408                 return;
1409         }
1410
1411         p += 4;
1412         l -= 4;
1413
1414         if (session[s].snoop_ip && session[s].snoop_port)
1415         {
1416                 // Snooping this session
1417                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
1418         }
1419
1420         increment_counter(&session[s].cin, &session[s].cin_wrap, l);
1421         session[s].cin_delta += l;
1422         session[s].pin++;
1423
1424         sess_local[s].cin += l;
1425         sess_local[s].pin++;
1426
1427         eth_tx += l;
1428
1429         STAT(tun_tx_packets);
1430         INC_STAT(tun_tx_bytes, l);
1431 }
1432
1433 // process IPv6 packet received
1434 //
1435 // This MUST be called with at least 4 byte behind 'p'.
1436 // (i.e. this routine writes to p[-4]).
1437 void processipv6in(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1438 {
1439         struct in6_addr ip;
1440         in_addr_t ipv4;
1441
1442         CSTAT(processipv6in);
1443
1444         LOG_HEX(5, "IPv6", p, l);
1445
1446         ip = *(struct in6_addr *) (p + 8);
1447         ipv4 = ntohl(*(uint32_t *)(p + 16));
1448
1449         if (l > MAXETHER)
1450         {
1451                 LOG(1, s, t, "IP packet too long %d\n", l);
1452                 STAT(tunnel_rx_errors);
1453                 return ;
1454         }
1455
1456         if (session[s].ppp.phase != Network || session[s].ppp.ipv6cp != Opened)
1457                 return;
1458
1459         // no spoof
1460         if (ipv4 != session[s].ip && memcmp(&config->ipv6_prefix, &ip, 8) && sessionbyipv6(ip) != s)
1461         {
1462                 char str[INET6_ADDRSTRLEN];
1463                 LOG(5, s, t, "Dropping packet with spoofed IP %s\n",
1464                                 inet_ntop(AF_INET6, &ip, str, INET6_ADDRSTRLEN));
1465                 return;
1466         }
1467
1468         // Check if it's a Router Solicition message.
1469         if (*(p + 6) == 58 && *(p + 7) == 255 && *(p + 24) == 0xFF && *(p + 25) == 2 &&
1470                         *(uint32_t *)(p + 26) == 0 && *(uint32_t *)(p + 30) == 0 &&
1471                         *(uint32_t *)(p + 34) == 0 &&
1472                         *(p + 38) == 0 && *(p + 39) == 2 && *(p + 40) == 133) {
1473                 LOG(3, s, t, "Got IPv6 RS\n");
1474                 send_ipv6_ra(s, t, &ip);
1475                 return;
1476         }
1477
1478         // Add on the tun header
1479         p -= 4;
1480         *(uint32_t *) p = htonl(PKTIPV6);
1481         l += 4;
1482
1483         // Are we throttled and a slave?
1484         if (session[s].tbf_in && !config->cluster_iam_master) {
1485                 // Pass it to the master for handling.
1486                 master_throttle_packet(session[s].tbf_in, p, l);
1487                 return;
1488         }
1489
1490         // Are we throttled and a master??
1491         if (session[s].tbf_in && config->cluster_iam_master) {
1492                 // Actually handle the throttled packets.
1493                 tbf_queue_packet(session[s].tbf_in, p, l);
1494                 return;
1495         }
1496
1497         // send to ethernet
1498         if (tun_write(p, l) < 0)
1499         {
1500                 STAT(tun_tx_errors);
1501                 LOG(0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1502                         l, strerror(errno), tunfd, p);
1503
1504                 return;
1505         }
1506
1507         p += 4;
1508         l -= 4;
1509
1510         if (session[s].snoop_ip && session[s].snoop_port)
1511         {
1512                 // Snooping this session
1513                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
1514         }
1515
1516         increment_counter(&session[s].cin, &session[s].cin_wrap, l);
1517         session[s].cin_delta += l;
1518         session[s].pin++;
1519
1520         sess_local[s].cin += l;
1521         sess_local[s].pin++;
1522
1523         eth_tx += l;
1524
1525         STAT(tun_tx_packets);
1526         INC_STAT(tun_tx_bytes, l);
1527 }
1528
1529 //
1530 // Helper routine for the TBF filters.
1531 // Used to send queued data in from the user.
1532 //
1533 void send_ipin(sessionidt s, uint8_t *buf, int len)
1534 {
1535         LOG_HEX(5, "IP in throttled", buf, len);
1536
1537         if (write(tunfd, buf, len) < 0)
1538         {
1539                 STAT(tun_tx_errors);
1540                 LOG(0, 0, 0, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1541                         len, strerror(errno), tunfd, buf);
1542
1543                 return;
1544         }
1545
1546         buf += 4;
1547         len -= 4;
1548
1549         if (session[s].snoop_ip && session[s].snoop_port)
1550         {
1551                 // Snooping this session
1552                 snoop_send_packet(buf, len, session[s].snoop_ip, session[s].snoop_port);
1553         }
1554
1555         // Increment packet counters
1556         increment_counter(&session[s].cin, &session[s].cin_wrap, len);
1557         session[s].cin_delta += len;
1558         session[s].pin++;
1559
1560         sess_local[s].cin += len;
1561         sess_local[s].pin++;
1562
1563         eth_tx += len;
1564
1565         STAT(tun_tx_packets);
1566         INC_STAT(tun_tx_bytes, len - 4);
1567 }
1568
1569
1570 // Process CCP messages
1571 void processccp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
1572 {
1573         uint8_t b[MAXETHER];
1574         uint8_t *q;
1575
1576         CSTAT(processccp);
1577
1578         LOG_HEX(5, "CCP", p, l);
1579
1580         if (session[s].ppp.phase < Network)
1581         {
1582                 LOG(2, s, t, "CCP %s ignored in %s phase\n", ppp_code(*p), ppp_phase(session[s].ppp.phase));
1583                 return;
1584         }
1585
1586         if (l < 1)
1587         {
1588                 LOG(1, s, t, "Short CCP packet\n");
1589                 STAT(tunnel_rx_errors);
1590         }
1591
1592         LOG(3, s, t, "CCP: recv %s\n", ppp_code(*p));
1593         if (*p == ConfigAck)
1594         {
1595                 switch (session[s].ppp.ccp)
1596                 {
1597                 case RequestSent:
1598                         initialise_restart_count(s, ccp);
1599                         change_state(s, ccp, AckReceived);
1600                         break;
1601
1602                 case AckReceived:
1603                 case Opened:
1604                         LOG(2, s, t, "CCP: ConfigAck in state %s?  Sending ConfigReq\n", ppp_state(session[s].ppp.ccp));
1605                         sendccp(s, t);
1606                         change_state(s, ccp, RequestSent);
1607                         break;
1608
1609                 case AckSent:
1610                         LOG(3, s, t, "CCP: Opened\n");
1611                         change_state(s, ccp, Opened);
1612                         break;
1613
1614                 default:
1615                         LOG(2, s, t, "CCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ccp));
1616                 }
1617         }
1618         else if (*p == ConfigReq)
1619         {
1620                 if (l < 6) // accept no compression
1621                         *p = ConfigAck;
1622                 else // compression requested--reject
1623                         *p = ConfigRej;
1624
1625                 q = makeppp(b, sizeof(b), p, l, s, t, PPPCCP);
1626                 if (!q) return;
1627
1628                 switch (session[s].ppp.ccp)
1629                 {
1630                 case Closed:
1631                         q = makeppp(b, sizeof(b), p, 2, s, t, PPPCCP);
1632                         if (!q) return;
1633                         *q = TerminateAck;
1634                         *((uint16_t *) (q + 2)) = htons(l = 4);
1635                         break;
1636
1637                 case Stopped:
1638                         initialise_restart_count(s, ccp);
1639                         sendccp(s, t);
1640                         if (*q == ConfigAck)
1641                                 change_state(s, ccp, AckSent);
1642                         else
1643                                 change_state(s, ccp, RequestSent);
1644
1645                         break;
1646
1647                 case RequestSent:
1648                         if (*q == ConfigAck)
1649                                 change_state(s, ccp, AckSent);
1650
1651                         break;
1652
1653                 case AckReceived:
1654                         if (*q == ConfigAck)
1655                                 change_state(s, ccp, Opened);
1656
1657                         break;
1658
1659                 case Opened:
1660                         initialise_restart_count(s, ccp);
1661                         sendccp(s, t);
1662                         /* fallthrough */
1663
1664                 case AckSent:
1665                         if (*q == ConfigAck)
1666                                 change_state(s, ccp, AckSent);
1667                         else
1668                                 change_state(s, ccp, RequestSent);
1669
1670                         break;
1671
1672                 default:
1673                         LOG(2, s, t, "CCP: ignoring %s in state %s\n", ppp_code(*p), ppp_state(session[s].ppp.ccp));
1674                         return;
1675                 }
1676
1677                 LOG(3, s, t, "CCP: send %s\n", ppp_code(*q));
1678                 tunnelsend(b, l + (q - b), t);
1679         }
1680         else if (*p == TerminateReq)
1681         {
1682                 *p = TerminateAck;
1683                 q = makeppp(b, sizeof(b),  p, l, s, t, PPPCCP);
1684                 if (!q) return;
1685                 LOG(3, s, t, "CCP: send %s\n", ppp_code(*q));
1686                 tunnelsend(b, l + (q - b), t);
1687                 change_state(s, ccp, Stopped);
1688         }
1689         else if (*p != CodeRej)
1690         {
1691                 ppp_code_rej(s, t, PPPCCP, "CCP", p, l, b, sizeof(b));
1692         }
1693 }
1694
1695 // send a CHAP challenge
1696 void sendchap(sessionidt s, tunnelidt t)
1697 {
1698         uint8_t b[MAXETHER];
1699         uint16_t r;
1700         uint8_t *q;
1701
1702         CSTAT(sendchap);
1703
1704         r = radiusnew(s);
1705         if (!r)
1706         {
1707                 LOG(1, s, t, "No RADIUS to send challenge\n");
1708                 STAT(tunnel_tx_errors);
1709                 return;
1710         }
1711
1712         LOG(1, s, t, "Send CHAP challenge\n");
1713
1714         radius[r].chap = 1;             // CHAP not PAP
1715         radius[r].id++;
1716         if (radius[r].state != RADIUSCHAP)
1717                 radius[r].try = 0;
1718
1719         radius[r].state = RADIUSCHAP;
1720         radius[r].retry = backoff(radius[r].try++);
1721         if (radius[r].try > 5)
1722         {
1723                 sessionshutdown(s, "CHAP timeout.", 3, 0);
1724                 STAT(tunnel_tx_errors);
1725                 return ;
1726         }
1727         q = makeppp(b, sizeof(b), 0, 0, s, t, PPPCHAP);
1728         if (!q) return;
1729
1730         *q = 1;                                 // challenge
1731         q[1] = radius[r].id;                    // ID
1732         q[4] = 16;                              // value size (size of challenge)
1733         memcpy(q + 5, radius[r].auth, 16);      // challenge
1734         strcpy((char *) q + 21, hostname);      // our name
1735         *(uint16_t *) (q + 2) = htons(strlen(hostname) + 21); // length
1736         tunnelsend(b, strlen(hostname) + 21 + (q - b), t); // send it
1737 }
1738
1739 // fill in a L2TP message with a PPP frame,
1740 // copies existing PPP message and changes magic number if seen
1741 // returns start of PPP frame
1742 uint8_t *makeppp(uint8_t *b, int size, uint8_t *p, int l, sessionidt s, tunnelidt t, uint16_t mtype)
1743 {
1744         if (size < 12) // Need more space than this!!
1745         {
1746                 static int backtrace_count = 0;
1747                 LOG(0, s, t, "makeppp buffer too small for L2TP header (size=%d)\n", size);
1748                 log_backtrace(backtrace_count, 5)
1749                 return NULL;
1750         }
1751
1752         *(uint16_t *) (b + 0) = htons(0x0002); // L2TP with no options
1753         *(uint16_t *) (b + 2) = htons(tunnel[t].far); // tunnel
1754         *(uint16_t *) (b + 4) = htons(session[s].far); // session
1755         b += 6;
1756         if (mtype == PPPLCP || !(session[s].flags & SESSION_ACFC))
1757         {
1758                 *(uint16_t *) b = htons(0xFF03); // HDLC header
1759                 b += 2;
1760         }
1761         if (mtype < 0x100 && session[s].flags & SESSION_PFC)
1762                 *b++ = mtype;
1763         else
1764         {
1765                 *(uint16_t *) b = htons(mtype);
1766                 b += 2;
1767         }
1768
1769         if (l + 12 > size)
1770         {
1771                 static int backtrace_count = 0;
1772                 LOG(2, s, t, "makeppp would overflow buffer (size=%d, header+payload=%d)\n", size, l + 12);
1773                 log_backtrace(backtrace_count, 5)
1774                 return NULL;
1775         }
1776
1777         if (p && l)
1778                 memcpy(b, p, l);
1779
1780         return b;
1781 }
1782
1783 static int add_lcp_auth(uint8_t *b, int size, int authtype)
1784 {
1785         int len = 0;
1786         if ((authtype == AUTHCHAP && size < 5) || size < 4)
1787                 return 0;
1788
1789         *b++ = 3; // Authentication-Protocol
1790         if (authtype == AUTHCHAP)
1791         {
1792                 len = *b++ = 5; // length
1793                 *(uint16_t *) b = htons(PPPCHAP); b += 2;
1794                 *b++ = 5; // MD5
1795         }
1796         else if (authtype == AUTHPAP)
1797         {
1798                 len = *b++ = 4; // length
1799                 *(uint16_t *) b = htons(PPPPAP); b += 2;
1800         }
1801         else
1802         {
1803                 LOG(0, 0, 0, "add_lcp_auth called with unsupported auth type %d\n", authtype);
1804         }
1805
1806         return len;
1807 }
1808
1809 // Send initial LCP ConfigReq for MRU, authentication type and magic no
1810 void sendlcp(sessionidt s, tunnelidt t)
1811 {
1812         uint8_t b[500], *q, *l;
1813         int authtype = sess_local[s].lcp_authtype;
1814
1815         if (!(q = makeppp(b, sizeof(b), NULL, 0, s, t, PPPLCP)))
1816                 return;
1817
1818         LOG(3, s, t, "LCP: send ConfigReq%s%s%s\n",
1819             authtype ? " (" : "",
1820             authtype ? (authtype == AUTHCHAP ? "CHAP" : "PAP") : "",
1821             authtype ? ")" : "");
1822
1823         l = q;
1824         *l++ = ConfigReq;
1825         *l++ = ++sess_local[s].lcp_ident; // ID
1826
1827         l += 2; //Save space for length
1828
1829         if (sess_local[s].ppp_mru)
1830         {
1831                 *l++ = 1; *l++ = 4; // Maximum-Receive-Unit (length 4)
1832                 *(uint16_t *) l = htons(sess_local[s].ppp_mru); l += 2;
1833         }
1834
1835         if (authtype)
1836                 l += add_lcp_auth(l, sizeof(b) - (l - b), authtype);
1837
1838         *l++ = 5; *l++ = 6; // Magic-Number (length 6)
1839         *(uint32_t *) l = htonl(session[s].magic);
1840         l += 4;
1841
1842         *(uint16_t *)(q + 2) = htons(l - q); // Length
1843
1844         LOG_HEX(5, "PPPLCP", q, l - q);
1845         if (config->debug > 3) dumplcp(q, l - q);
1846
1847         tunnelsend(b, (l - b), t);
1848         restart_timer(s, lcp);
1849 }
1850
1851 // Send CCP request for no compression
1852 void sendccp(sessionidt s, tunnelidt t)
1853 {
1854         uint8_t b[500], *q;
1855
1856         if (!(q = makeppp(b, sizeof(b), NULL, 0, s, t, PPPCCP)))
1857                 return;
1858
1859         LOG(3, s, t, "CCP: send ConfigReq (no compression)\n");
1860
1861         *q = ConfigReq;
1862         *(q + 1) = ++sess_local[s].lcp_ident; // ID
1863         *(uint16_t *)(q + 2) = htons(4); // Length
1864
1865         LOG_HEX(5, "PPPCCP", q, 4);
1866         tunnelsend(b, (q - b) + 4 , t);
1867         restart_timer(s, ccp);
1868 }