ppp.c

   1 // L2TPNS PPP Stuff
   2 // $Id: ppp.c,v 1.5 2004-06-23 03:52:24 fred_nerk Exp $
   3
   4 #include <stdio.h>
   5 #include <string.h>
   6 #include <unistd.h>
   7 #include <errno.h>
   8 #include <stdlib.h>
   9 #include "l2tpns.h"
  10 #include "constants.h"
  11 #include "plugin.h"
  12 #include "util.h"
  13 #include "tbf.h"
  14 #include "cluster.h"
  15
  16 extern tunnelt *tunnel;
  17 extern sessiont *session;
  18 extern radiust *radius;
  19 extern int tapfd;
  20 extern char hostname[];
  21 extern u32 eth_tx;
  22 extern time_t time_now;
  23 extern struct configt *config;
  24
  25 // Process PAP messages
  26 void processpap(tunnelidt t, sessionidt s, u8 * p, u16 l)
  27 {
  28         char user[129];
  29         char pass[129];
  30
  31 #ifdef STAT_CALLS
  32         STAT(call_processpap);
  33 #endif
  34         log_hex(5, "PAP", p, l);
  35         if (l < 4)
  36         {
  37                 log(1, 0, s, t, "Short PAP %u bytes", l);
  38                 STAT(tunnel_rx_errors);
  39                 return ;
  40         }
  41         if (*p != 1)
  42         {
  43                 log(1, 0, s, t, "Unexpected PAP code %d\n", *p);
  44                 STAT(tunnel_rx_errors);
  45                 return ;
  46         }
  47         if (ntohs(*(u16 *) (p + 2)) > l)
  48         {
  49                 log(1, 0, s, t, "Length mismatch PAP %d/%d\n", ntohs(*(u16 *) (p + 2)), l);
  50                 STAT(tunnel_rx_errors);
  51                 return ;
  52         }
  53         {
  54                 u8 *b = p;
  55                 b += 4;
  56                 if (*b && *b < sizeof(user))
  57                         memcpy(user, b + 1, *b);
  58                 user[*b] = 0;
  59                 b += 1 + *b;
  60                 if (*b && *b < sizeof(pass))
  61                         memcpy(pass, b + 1, *b);
  62                 pass[*b] = 0;
  63                 log(3, 0, s, t, "PAP login %s/%s\n", user, pass);
  64         }
  65         if (session[s].ip || !session[s].radius)
  66         {
  67                 // respond now, either no RADIUS available or already authenticated
  68                 u8 b[MAXCONTROL];
  69                 u8 id = p[1];
  70                 u8 *p = makeppp(b, sizeof(b), 0, 0, t, s, PPPPAP);
  71                 if (!p) {       // Failed to make ppp header!
  72                         log(1,0,0,0, "Failed to make PPP header in process pap!\n");
  73                         return;
  74                 }
  75                 if (session[s].ip)
  76                         *p = 2;              // ACK
  77                 else
  78                         *p = 3;              // cant authorise
  79                 p[1] = id;
  80                 *(u16 *) (p + 2) = htons(5); // length
  81                 p[4] = 0;               // no message
  82                 if (session[s].ip)
  83                 {
  84                     log(3, session[s].ip, s, t, "%d Already an IP allocated: %s (%d)\n", getpid(), inet_toa(htonl(session[s].ip)), session[s].ip_pool_index);
  85                 }
  86                 else
  87                 {
  88                     log(1, 0, s, t, "No radius session available to authenticate session...\n");
  89                 }
  90                 log(3, 0, s, t, "Fallback response to PAP (%s)\n", (session[s].ip) ? "ACK" : "NAK");
  91                 tunnelsend(b, 5 + (p - b), t); // send it
  92         }
  93         else
  94         {                          // set up RADIUS request
  95                 u16 r = session[s].radius;
  96
  97                 // Run PRE_AUTH plugins
  98                 struct param_pre_auth packet = { &tunnel[t], &session[s], strdup(user), strdup(pass), PPPPAP, 1 };
  99                 run_plugins(PLUGIN_PRE_AUTH, &packet);
 100                 if (!packet.continue_auth)
 101                 {
 102                         log(3, 0, s, t, "A plugin rejected PRE_AUTH\n");
 103                         if (packet.username) free(packet.username);
 104                         if (packet.password) free(packet.password);
 105                         return;
 106                 }
 107
 108                 strncpy(session[s].user, packet.username, sizeof(session[s].user) - 1);
 109                 strncpy(radius[r].pass, packet.password, sizeof(radius[r].pass) - 1);
 110
 111                 free(packet.username);
 112                 free(packet.password);
 113
 114                 radius[r].id = p[1];
 115                 log(3, 0, s, t, "Sending login for %s/%s to radius\n", user, pass);
 116                 radiussend(r, RADIUSAUTH);
 117         }
 118 }
 119
 120 // Process CHAP messages
 121 void processchap(tunnelidt t, sessionidt s, u8 * p, u16 l)
 122 {
 123         u16 r;
 124         u16 len;
 125
 126 #ifdef STAT_CALLS
 127         STAT(call_processchap);
 128 #endif
 129         log_hex(5, "CHAP", p, l);
 130         r = session[s].radius;
 131         if (!r)
 132         {
 133                 log(1, 0, s, t, "Unexpected CHAP message\n");
 134
 135 // FIXME: Need to drop the session here.
 136
 137                 STAT(tunnel_rx_errors);
 138                 return;
 139         }
 140         if (*p != 2)
 141         {
 142                 log(1, 0, s, t, "Unexpected CHAP response code %d\n", *p);
 143                 STAT(tunnel_rx_errors);
 144                 return;
 145         }
 146         if (p[1] != radius[r].id)
 147         {
 148                 log(1, 0, s, t, "Wrong CHAP response ID %d (should be %d) (%d)\n", p[1], radius[r].id, r);
 149                 STAT(tunnel_rx_errors);
 150                 return ;
 151         }
 152         len = ntohs(*(u16 *) (p + 2));
 153         if (len > l)
 154         {
 155                 log(1, 0, s, t, "Bad CHAP length %d\n", len);
 156                 STAT(tunnel_rx_errors);
 157                 return ;
 158         }
 159         if (p[4] != 16)
 160         {
 161                 log(1, 0, s, t, "Bad CHAP response length %d\n", p[4]);
 162                 STAT(tunnel_rx_errors);
 163                 return ;
 164         }
 165         if (len - 21 >= sizeof(session[s].user))
 166         {
 167                 log(1, 0, s, t, "CHAP user too long %d\n", len - 21);
 168                 STAT(tunnel_rx_errors);
 169                 return ;
 170         }
 171
 172         // Run PRE_AUTH plugins
 173         {
 174                 struct param_pre_auth packet = { &tunnel[t], &session[s], NULL, NULL, PPPCHAP, 1 };
 175
 176                 packet.username = calloc(len-20, 1);
 177                 packet.password = calloc(16, 1);
 178                 memcpy(packet.username, p + 21, len - 21);
 179                 memcpy(packet.password, p + 5, 16);
 180
 181                 run_plugins(PLUGIN_PRE_AUTH, &packet);
 182                 if (!packet.continue_auth)
 183                 {
 184                         log(3, 0, s, t, "A plugin rejected PRE_AUTH\n");
 185                         if (packet.username) free(packet.username);
 186                         if (packet.password) free(packet.password);
 187                         return;
 188                 }
 189
 190                 strncpy(session[s].user, packet.username, sizeof(session[s].user) - 1);
 191                 memcpy(radius[r].pass, packet.password, 16);
 192
 193                 free(packet.username);
 194                 free(packet.password);
 195         }
 196
 197         radius[r].chap = 1;
 198         log(3, 0, s, t, "CHAP login %s\n", session[s].user);
 199         radiussend(r, RADIUSAUTH);
 200 }
 201
 202 char *ppp_lcp_types[] = {
 203         NULL,
 204         "ConfigReq",
 205         "ConfigAck",
 206         "ConfigNak",
 207         "ConfigRej",
 208         "TerminateReq",
 209         "TerminateAck",
 210         "CodeRej",
 211         "ProtocolRej",
 212         "EchoReq",
 213         "EchoReply",
 214         "DiscardRequest",
 215 };
 216
 217 void dumplcp(u8 *p, int l)
 218 {
 219         signed int x = l - 4;
 220         u8 *o = (p + 4);
 221
 222         log_hex(5, "PPP LCP Packet", p, l);
 223         log(4, 0, 0, 0, "PPP LCP Packet type %d (%s len %d)\n", *p, ppp_lcp_types[(int)*p], ntohs( ((u16 *) p)[1]) );
 224         log(4, 0, 0, 0, "Length: %d\n", l);
 225         if (*p != ConfigReq && *p != ConfigRej && *p != ConfigAck)
 226                 return;
 227
 228         while (x > 2)
 229         {
 230                 int type = o[0];
 231                 int length = o[1];
 232                 if (length == 0)
 233                 {
 234                         log(4, 0, 0, 0, "       Option length is 0...\n");
 235                         break;
 236                 }
 237                 if (type == 0)
 238                 {
 239                         log(4, 0, 0, 0, "       Option type is 0...\n");
 240                         x -= length;
 241                         o += length;
 242                         continue;
 243                 }
 244                 switch (type)
 245                 {
 246                         case 1: // Maximum-Receive-Unit
 247                                 log(4, 0, 0, 0, "    %s %d\n", lcp_types[type], ntohs(*(u16 *)(o + 2)));
 248                                 break;
 249                         case 3: // Authentication-Protocol
 250                                 {
 251                                         int proto = ntohs(*(u16 *)(o + 2));
 252                                         log(4, 0, 0, 0, "    %s %s\n", lcp_types[type],
 253                                                         proto == 0xC223 ? "CHAP" : "PAP");
 254                                         break;
 255                                 }
 256                         case 4: // Quality-Protocol
 257                                 {
 258                                         u32 qp = ntohl(*(u32 *)(o + 2));
 259                                         log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], qp);
 260                                         break;
 261                                 }
 262                         case 5: // Magic-Number
 263                                 {
 264                                         u32 magicno = ntohl(*(u32 *)(o + 2));
 265                                         log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], magicno);
 266                                         break;
 267                                 }
 268                         case 7: // Protocol-Field-Compression
 269                                 {
 270                                         u32 pfc = ntohl(*(u32 *)(o + 2));
 271                                         log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], pfc);
 272                                         break;
 273                                 }
 274                         case 8: // Address-And-Control-Field-Compression
 275                                 {
 276                                         u32 afc = ntohl(*(u32 *)(o + 2));
 277                                         log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], afc);
 278                                         break;
 279                                 }
 280                         default:
 281                                 log(2, 0, 0, 0, "    Unknown PPP LCP Option type %d\n", type);
 282                                 break;
 283                 }
 284                 x -= length;
 285                 o += length;
 286         }
 287 }
 288
 289 // Process LCP messages
 290 void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 291 {
 292         u8 b[MAXCONTROL];
 293         u8 *q = NULL;
 294
 295 #ifdef STAT_CALLS
 296         STAT(call_processlcp);
 297 #endif
 298         log_hex(5, "LCP", p, l);
 299         if (l < 4)
 300         {
 301                 log(1, session[s].ip, s, t, "Short LCP %d bytes", l);
 302                 STAT(tunnel_rx_errors);
 303                 return ;
 304         }
 305         if (*p == ConfigAck)
 306         {
 307                 log(3, session[s].ip, s, t, "LCP: Discarding ConfigAck\n");
 308         }
 309         else if (*p == ConfigReq)
 310         {
 311                 signed int x = l - 4;
 312                 u8 *o = (p + 4);
 313
 314                 log(3, session[s].ip, s, t, "LCP: ConfigReq (%d bytes)...\n", l);
 315                 dumplcp(p, l);
 316
 317                 while (x > 2)
 318                 {
 319                         int type = o[0];
 320                         int length = o[1];
 321                         if (length == 0 || type == 0) break;
 322                         switch (type)
 323                         {
 324                                 case 1: // Maximum-Receive-Unit
 325                                         session[s].mru = ntohs(*(u16 *)(o + 2));
 326                                         break;
 327                                 case 3: // Authentication-Protocol
 328                                         {
 329                                                 int proto = ntohs(*(u16 *)(o + 2));
 330                                                 if (proto == 0xC223)
 331                                                 {
 332                                                         log(2, session[s].ip, s, t, "    Remote end is trying to do CHAP. Rejecting it.\n");
 333
 334                                                         if (!q)
 335                                                         {
 336                                                                 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 337                                                                 if (!q) {
 338                                                                         log(2, session[s].ip, s, t, " Failed to send packet.\n");
 339                                                                         break;
 340                                                                 }
 341                                                                 *q++ = ConfigNak;
 342                                                         }
 343                                                         memcpy(q, o, length);
 344                                                         *(u16 *)(q += 2) = htons(0xC023); // NAK -> Use PAP instead
 345                                                         q += length;
 346                                                 }
 347                                                 break;
 348                                         }
 349                                 case 5: // Magic-Number
 350                                         {
 351 //                                              u32 magicno = ntohl(*(u32 *)(o + 2));
 352                                                 break;
 353                                         }
 354                                 case 4: // Quality-Protocol
 355                                         {
 356 //                                              u32 qp = ntohl(*(u32 *)(o + 2));
 357                                                 break;
 358                                         }
 359                                 case 7: // Protocol-Field-Compression
 360                                         {
 361 //                                              u32 pfc = ntohl(*(u32 *)(o + 2));
 362                                                 break;
 363                                         }
 364                                 case 8: // Address-And-Control-Field-Compression
 365                                         {
 366 //                                              u32 afc = ntohl(*(u32 *)(o + 2));
 367                                                 break;
 368                                         }
 369                                 default:
 370                                         log(2, session[s].ip, s, t, "    Unknown PPP LCP Option type %d\n", type);
 371                                         break;
 372                         }
 373                         x -= length;
 374                         o += length;
 375                 }
 376
 377                 if (!q)
 378                 {
 379                         // Send back a ConfigAck
 380                         log(3, session[s].ip, s, t, "ConfigReq accepted, sending as Ack\n");
 381                         q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 382                         if (!q) {
 383                                 log(3, session[s].ip, s, t, " failed to create packet.\n");
 384                                 return;
 385                         }
 386                         *q = ConfigAck;
 387                         tunnelsend(b, l + (q - b), t);
 388                 }
 389                 else
 390                 {
 391                         // Already built a ConfigNak... send it
 392                         log(3, session[s].ip, s, t, "Sending ConfigNak\n");
 393                         tunnelsend(b, l + (q - b), t);
 394
 395                         log(3, session[s].ip, s, t, "Sending ConfigReq, requesting PAP login\n");
 396                         q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPLCP);
 397                         *q++ = ConfigReq;
 398                         *(u8 *)(q++) = 3;
 399                         *(u8 *)(q++) = 4;
 400                         *(u16 *)(q += 2) = htons(0xC023);
 401                         tunnelsend(b, l + (q - b), t);
 402                 }
 403         }
 404         else if (*p == ConfigNak)
 405         {
 406                 log(1, session[s].ip, s, t, "Remote end sent a ConfigNak. Ignoring\n");
 407                 dumplcp(p, l);
 408                 return ;
 409         }
 410         else if (*p == TerminateReq)
 411         {
 412                 *p = TerminateAck;     // close
 413                 q = makeppp(b, sizeof(b),  p, l, t, s, PPPLCP);
 414                 if (!q) {
 415                         log(3, session[s].ip, s, t, "Failed to create PPP packet in processlcp.\n");
 416                         return;
 417                 }
 418                 log(3, session[s].ip, s, t, "LCP: Received TerminateReq. Sending TerminateAck\n");
 419                 sessionshutdown(s, "Remote end closed connection.");
 420                 tunnelsend(b, l + (q - b), t); // send it
 421         }
 422         else if (*p == TerminateReq)
 423         {
 424                 sessionshutdown(s, "Remote end closed connection.");
 425         }
 426         else if (*p == EchoReq)
 427         {
 428                 *p = EchoReply;      // reply
 429                 *(u32 *) (p + 4) = htonl(session[s].magic); // our magic number
 430                 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 431                 if (!q) {
 432                         log(3, session[s].ip, s, t, " failed to send EchoReply.\n");
 433                         return;
 434                 }
 435                 log(5, session[s].ip, s, t, "LCP: Received EchoReq. Sending EchoReply\n");
 436                 tunnelsend(b, l + (q - b), t); // send it
 437         }
 438         else if (*p == EchoReply)
 439         {
 440                 // Ignore it, last_packet time is set earlier than this.
 441         }
 442         else
 443         {
 444                 log(1, session[s].ip, s, t, "Unexpected LCP code %d\n", *p);
 445                 STAT(tunnel_rx_errors);
 446                 return ;
 447         }
 448 }
 449
 450 // Process IPCP messages
 451 void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 452 {
 453 #ifdef STAT_CALLS
 454         STAT(call_processipcp);
 455 #endif
 456         log_hex(5, "IPCP", p, l);
 457         if (l < 5)
 458         {
 459                 log(1, 0, s, t, "Short IPCP %d bytes", l);
 460                 STAT(tunnel_rx_errors);
 461                 return ;
 462         }
 463         if (*p == ConfigAck)
 464         {                          // happy with our IPCP
 465                 u16 r = session[s].radius;
 466                 if ((!r || radius[r].state == RADIUSIPCP) && !session[s].walled_garden) {
 467                         if (!r)
 468                                 r = radiusnew(s);
 469                         if (r)
 470                                 radiussend(r, RADIUSSTART); // send radius start, having got IPCP at last
 471                 }
 472                 session[s].flags |= SF_IPCP_ACKED;
 473
 474                 return ;                 // done
 475         }
 476         if (*p != ConfigReq)
 477         {
 478                 log(1, 0, s, t, "Unexpected IPCP code %d\n", *p);
 479                 STAT(tunnel_rx_errors);
 480                 return ;
 481         }
 482         if (ntohs(*(u16 *) (p + 2)) > l)
 483         {
 484                 log(1, 0, s, t, "Length mismatch IPCP %d/%d\n", ntohs(*(u16 *) (p + 2)), l);
 485                 STAT(tunnel_rx_errors);
 486                 return ;
 487         }
 488         if (!session[s].ip)
 489         {
 490                 log(3, 0, s, t, "Waiting on radius reply\n");
 491                 return ;                   // have to wait on RADIUS reply
 492         }
 493         // form a config reply quoting the IP in the session
 494         {
 495                 u8 b[MAXCONTROL];
 496                 u8 *i,
 497                 *q;
 498
 499                 q = p + 4;
 500                 i = p + l;
 501                 while (q < i && q[1])
 502                 {
 503                         if (*q != 0x81 && *q != 0x83 && *q != 3)
 504                                 break;
 505                         q += q[1];
 506                 }
 507                 if (q < i)
 508                 {                       // reject
 509                         u16 n = 4;
 510                         i = p + l;
 511                         q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP);
 512                         if (!q) {
 513                                 log(2, 0, s, t, "Failed to send IPCP.\n");
 514                                 return;
 515                         }
 516                         *q = ConfigRej;
 517                         p += 4;
 518                         while (p < i && p[1])
 519                         {
 520                                 if (*p != 0x81 && *p != 0x83 && *p != 3)
 521                                 {
 522                                         log(2, 0, s, t, "IPCP reject %d\n", *p);
 523                                         memcpy(q + n, p, p[1]);
 524                                         n += p[1];
 525                                 }
 526                                 p += p[1];
 527                         }
 528                         *(u16 *) (q + 2) = htons(n);
 529                         tunnelsend(b, n + (q - b), t); // send it
 530                 }
 531                 else
 532                 {
 533                         *p = ConfigAck;
 534                         i = findppp(p, 0x81); // Primary DNS address
 535                         if (i)
 536                         {
 537                                 if (*(u32 *) (i + 2) != htonl(session[s].dns1))
 538                                 {
 539                                         *(u32 *) (i + 2) = htonl(session[s].dns1);
 540                                         *p = ConfigNak;
 541                                 }
 542                         }
 543                         i = findppp(p, 0x83); // Secondary DNS address (TBA, is it)
 544                         if (i)
 545                         {
 546                                 if (*(u32 *) (i + 2) != htonl(session[s].dns2))
 547                                 {
 548                                         *(u32 *) (i + 2) = htonl(session[s].dns2);
 549                                         *p = ConfigNak;
 550                                 }
 551                         }
 552                         i = findppp(p, 3);   // IP address
 553                         if (!i || i[1] != 6)
 554                         {
 555                                 log(1, 0, s, t, "No IP in IPCP request\n");
 556                                 STAT(tunnel_rx_errors);
 557                                 return ;
 558                         }
 559                         if (*(u32 *) (i + 2) != htonl(session[s].ip))
 560                         {
 561                                 *(u32 *) (i + 2) = htonl(session[s].ip);
 562                                 *p = ConfigNak;
 563                         }
 564                         q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP);
 565                         if (!q) {
 566                                 log(2, 0, s, t, " Failed to send IPCP packet.\n");
 567                                 return;
 568                         }
 569                         tunnelsend(b, l + (q - b), t); // send it
 570                 }
 571         }
 572 }
 573
 574 // process IP packet received
 575 //
 576 // This MUST be called with at least 4 byte behind 'p'.
 577 // (i.e. this routine writes to p[-4]).
 578 void processipin(tunnelidt t, sessionidt s, u8 * p, u16 l)
 579 {
 580         ipt ip;
 581
 582 #ifdef STAT_CALLS
 583         STAT(call_processipin);
 584 #endif
 585         log_hex(5, "IP", p, l);
 586
 587         ip = ntohl(*(u32 *)(p + 12));
 588
 589         if (l > MAXETHER)
 590         {
 591                 log(1, ip, s, t, "IP packet too long %d\n", l);
 592                 STAT(tunnel_rx_errors);
 593                 return ;
 594         }
 595
 596         // no spoof (do sessionbyip to handled statically routed subnets)
 597         if (ip != session[s].ip && sessionbyip(htonl(ip)) != s)
 598         {
 599                 log(5, ip, s, t, "Dropping packet with spoofed IP %s\n", inet_toa(htonl(ip)));
 600                 return;
 601         }
 602
 603         // Add on the tun header
 604         p -= 4;
 605         *(u32 *)p = htonl(0x00000800);
 606         l += 4;
 607
 608         if (session[s].tbf_in && !config->cluster_iam_master) { // Are we throttled and a slave?
 609                 master_throttle_packet(session[s].tbf_in, p, l); // Pass it to the master for handling.
 610                 return;
 611         }
 612
 613         session[s].cin += l - 4;
 614         session[s].total_cin += l - 4;
 615         sess_count[s].cin += l - 4;
 616
 617         session[s].pin++;
 618         eth_tx += l - 4;
 619
 620         if (session[s].snoop_ip && session[s].snoop_port)
 621         {
 622                 // Snooping this session, send it to ASIO
 623                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
 624         }
 625         STAT(tap_tx_packets);
 626         INC_STAT(tap_tx_bytes, l);
 627
 628         if (session[s].tbf_in && config->cluster_iam_master) { // Are we throttled and a master?? actually handle the throttled packets.
 629                 tbf_queue_packet(session[s].tbf_in, p, l);
 630                 return;
 631         }
 632
 633         // send to ethernet
 634         if (tun_write(p, l) < 0)
 635         {
 636                 STAT(tap_tx_errors);
 637                 log(0, 0, s, t, "Error writing %d bytes to TAP device: %s (tapfd=%d, p=%p)\n",
 638                         l, strerror(errno), tapfd, p);
 639         }
 640
 641 }
 642
 643 //
 644 // Helper routine for the TBF filters.
 645 // Used to send queued data in from the user.
 646 //
 647 void send_ipin(sessionidt s, u8 *buf, int len)
 648 {
 649         log_hex(5, "IP in throttled", buf, len);
 650         if (write(tapfd, buf, len) < 0)
 651         {
 652                 STAT(tap_tx_errors);
 653                 log(0, 0, 0, 0, "Error writing %d bytes to TAP device: %s (tapfd=%d, p=%p)\n",
 654                         len, strerror(errno), tapfd, buf);
 655         }
 656
 657         // Increment packet counters
 658         session[s].cin += len - 4;
 659         session[s].total_cin += len - 4;
 660         sess_count[s].cin += len - 4;
 661
 662         session[s].pin++;
 663         eth_tx += len - 4;
 664 }
 665
 666
 667 // Process LCP messages
 668 void processccp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 669 {
 670 #ifdef STAT_CALLS
 671         STAT(call_processccp);
 672 #endif
 673         log_hex(5, "CCP", p, l);
 674         if (l < 2 || (*p != ConfigReq && *p != TerminateReq))
 675         {
 676                 log(1, 0, s, t, "Unexpecetd CCP request code %d\n", *p);
 677                 STAT(tunnel_rx_errors);
 678                 return ;
 679         }
 680         // reject
 681         {
 682                 u8 b[MAXCONTROL];
 683                 u8 *q;
 684                 if (*p == ConfigReq)
 685                 {
 686                         if (l < 6)
 687                         {
 688                                 *p = ConfigAck;         // accept no compression
 689                         }
 690                         else
 691                         {
 692                                 *p = ConfigRej;        // reject
 693                         }
 694                 }
 695                 else
 696                         *p = TerminateAck;     // close
 697                 q = makeppp(b, sizeof(b), p, l, t, s, PPPCCP);
 698                 if (!q) {
 699                         log(1,0,0,0, "Failed to send CCP packet.\n");
 700                         return;
 701                 }
 702                 tunnelsend(b, l + (q - b), t); // send it
 703         }
 704 }
 705
 706 // send a CHAP PP packet
 707 void sendchap(tunnelidt t, sessionidt s)
 708 {
 709         u8 b[MAXCONTROL];
 710         u16 r = session[s].radius;
 711         u8 *q;
 712 #ifdef STAT_CALLS
 713         STAT(call_sendchap);
 714 #endif
 715         if (!r)
 716         {
 717                 log(1, 0, s, t, "No RADIUS to send challenge\n");
 718                 STAT(tunnel_tx_errors);
 719                 return ;
 720         }
 721         log(1, 0, s, t, "Send CHAP challenge\n");
 722         {                            // new challenge
 723                 int n;
 724                 for (n = 0; n < 15; n++)
 725                         radius[r].auth[n] = rand();
 726         }
 727         radius[r].chap = 1;          // CHAP not PAP
 728         radius[r].id++;
 729         if (radius[r].state != RADIUSCHAP)
 730                 radius[r].try = 0;
 731         radius[r].state = RADIUSCHAP;
 732         radius[r].retry = backoff(radius[r].try++);
 733         if (radius[r].try > 5)
 734         {
 735                 sessionshutdown(s, "Timeout CHAP");
 736                 STAT(tunnel_tx_errors);
 737                 return ;
 738         }
 739         q = makeppp(b, sizeof(b), 0, 0, t, s, PPPCHAP);
 740         if (!q) {
 741                 log(1, 0, s, t, "failed to send CHAP challenge.\n");
 742                 return;
 743         }
 744         *q = 1;                      // challenhe
 745         q[1] = radius[r].id;         // ID
 746         q[4] = 16;                   // length
 747         memcpy(q + 5, radius[r].auth, 16); // challenge
 748         strcpy(q + 21, hostname);    // our name
 749         *(u16 *) (q + 2) = htons(strlen(hostname) + 21); // length
 750         tunnelsend(b, strlen(hostname) + 21 + (q - b), t); // send it
 751 }
 752
 753 // fill in a L2TP message with a PPP frame,
 754 // copies existing PPP message and changes magic number if seen
 755 // returns start of PPP frame
 756 u8 *makeppp(u8 * b, int size, u8 * p, int l, tunnelidt t, sessionidt s, u16 mtype)
 757 {
 758
 759         if (size < 12)
 760                 return NULL;    // Need more space than this!!
 761
 762         *(u16 *) (b + 0) = htons(0x0002); // L2TP with no options
 763         *(u16 *) (b + 2) = htons(tunnel[t].far); // tunnel
 764         *(u16 *) (b + 4) = htons(session[s].far); // session
 765         b += 6;
 766         if (mtype != PPPLCP && !(session[s].l2tp_flags & SESSIONACFC))
 767         {
 768                 *(u16 *) b = htons(0xFF03); // HDLC header
 769                 b += 2;
 770         }
 771         if (mtype < 0x100 && session[s].l2tp_flags & SESSIONPFC)
 772                 *b++ = mtype;
 773         else
 774         {
 775                 *(u16 *) b = htons(mtype);
 776                 b += 2;
 777         }
 778
 779         if (l + 12 > size) {
 780                 log(3,0,0,0, "Would have overflowed the buffer in makeppp: size %d, len %d.\n", size, l);
 781                 return NULL;    // Run out of room to hold the packet!
 782         }
 783         if (p && l)
 784                 memcpy(b, p, l);
 785         return b;
 786 }
 787
 788 // find a PPP option, returns point to option, or 0 if not found
 789 u8 *findppp(u8 * b, u8 mtype)
 790 {
 791         u16 l = ntohs(*(u16 *) (b + 2));
 792         if (l < 4)
 793                 return 0;
 794         b += 4;
 795         l -= 4;
 796         while (l)
 797         {
 798                 if (l < b[1] || !b[1])
 799                         return 0;            // faulty
 800                 if (*b == mtype)
 801                         return b;
 802                 l -= b[1];
 803                 b += b[1];
 804         }
 805         return 0;
 806 }
 807
 808 // Send initial LCP ConfigReq
 809 void initlcp(tunnelidt t, sessionidt s)
 810 {
 811         char b[500] = {0}, *q;
 812
 813         q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPLCP);
 814         if (!q) {
 815                 log(1, 0, s, t, "Failed to send LCP ConfigReq.\n");
 816                 return;
 817         }
 818         log(4, 0, s, t, "Sending LCP ConfigReq for PAP\n");
 819         *q = ConfigReq;
 820         *(u8 *)(q + 1) = (time_now % 255) + 1; // ID
 821         *(u16 *)(q + 2) = htons(8); // Length
 822         *(u8 *)(q + 4) = 3;
 823         *(u8 *)(q + 5) = 4;
 824         *(u16 *)(q + 6) = htons(0xC023); // PAP
 825         tunnelsend(b, 12 + 8, t);
 826 }
 827