ppp.c

   1 // L2TPNS PPP Stuff
   2
   3 char const *cvs_id_ppp = "$Id: ppp.c,v 1.20 2004/11/05 02:21:55 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 u32 eth_tx;
  23 extern time_t time_now;
  24 extern struct configt *config;
  25
  26 void sendccp(tunnelidt t, sessionidt s);
  27
  28 // Process PAP messages
  29 void processpap(tunnelidt t, sessionidt s, u8 *p, u16 l)
  30 {
  31         char user[129];
  32         char pass[129];
  33         u16 hl;
  34
  35         CSTAT(call_processpap);
  36
  37         log_hex(5, "PAP", p, l);
  38         if (l < 4)
  39         {
  40                 log(1, 0, s, t, "Short PAP %u bytes\n", l);
  41                 STAT(tunnel_rx_errors);
  42                 return ;
  43         }
  44
  45         if ((hl = ntohs(*(u16 *) (p + 2))) > l)
  46         {
  47                 log(1, 0, s, t, "Length mismatch PAP %u/%u\n", hl, l);
  48                 STAT(tunnel_rx_errors);
  49                 return ;
  50         }
  51         l = hl;
  52
  53         if (*p != 1)
  54         {
  55                 log(1, 0, s, t, "Unexpected PAP code %d\n", *p);
  56                 STAT(tunnel_rx_errors);
  57                 return ;
  58         }
  59
  60         {
  61                 u8 *b = p;
  62                 b += 4;
  63                 if (*b && *b < sizeof(user))
  64                         memcpy(user, b + 1, *b);
  65                 user[*b] = 0;
  66                 b += 1 + *b;
  67                 if (*b && *b < sizeof(pass))
  68                         memcpy(pass, b + 1, *b);
  69                 pass[*b] = 0;
  70                 log(3, 0, s, t, "PAP login %s/%s\n", user, pass);
  71         }
  72         if (session[s].ip || !session[s].radius)
  73         {
  74                 // respond now, either no RADIUS available or already authenticated
  75                 u8 b[MAXCONTROL];
  76                 u8 id = p[1];
  77                 u8 *p = makeppp(b, sizeof(b), 0, 0, t, s, PPPPAP);
  78                 if (!p) {       // Failed to make ppp header!
  79                         log(1,0,0,0, "Failed to make PPP header in process pap!\n");
  80                         return;
  81                 }
  82                 if (session[s].ip)
  83                         *p = 2;                 // ACK
  84                 else
  85                         *p = 3;                 // cant authorise
  86                 p[1] = id;
  87                 *(u16 *) (p + 2) = htons(5);    // length
  88                 p[4] = 0;                       // no message
  89                 if (session[s].ip)
  90                 {
  91                         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);
  92                         session[s].flags &= ~SF_IPCP_ACKED;
  93                 }
  94                 else
  95                 {
  96                         log(1, 0, s, t, "No radius session available to authenticate session...\n");
  97                 }
  98                 log(3, 0, s, t, "Fallback response to PAP (%s)\n", (session[s].ip) ? "ACK" : "NAK");
  99                 tunnelsend(b, 5 + (p - b), t); // send it
 100         }
 101         else
 102         {
 103                 // set up RADIUS request
 104                 u16 r = session[s].radius;
 105
 106                 // Run PRE_AUTH plugins
 107                 struct param_pre_auth packet = { &tunnel[t], &session[s], strdup(user), strdup(pass), PPPPAP, 1 };
 108                 run_plugins(PLUGIN_PRE_AUTH, &packet);
 109                 if (!packet.continue_auth)
 110                 {
 111                         log(3, 0, s, t, "A plugin rejected PRE_AUTH\n");
 112                         if (packet.username) free(packet.username);
 113                         if (packet.password) free(packet.password);
 114                         return;
 115                 }
 116
 117                 strncpy(session[s].user, packet.username, sizeof(session[s].user) - 1);
 118                 strncpy(radius[r].pass, packet.password, sizeof(radius[r].pass) - 1);
 119
 120                 free(packet.username);
 121                 free(packet.password);
 122
 123                 radius[r].id = p[1];
 124                 log(3, 0, s, t, "Sending login for %s/%s to radius\n", user, pass);
 125                 radiussend(r, RADIUSAUTH);
 126         }
 127 }
 128
 129 // Process CHAP messages
 130 void processchap(tunnelidt t, sessionidt s, u8 *p, u16 l)
 131 {
 132         u16 r;
 133         u16 hl;
 134
 135         CSTAT(call_processchap);
 136
 137         log_hex(5, "CHAP", p, l);
 138         r = session[s].radius;
 139         if (!r)
 140         {
 141                 log(1, 0, s, t, "Unexpected CHAP message\n");
 142
 143 // FIXME: Need to drop the session here.
 144
 145                 STAT(tunnel_rx_errors);
 146                 return;
 147         }
 148
 149         if (l < 4)
 150         {
 151                 log(1, 0, s, t, "Short CHAP %u bytes\n", l);
 152                 STAT(tunnel_rx_errors);
 153                 return ;
 154         }
 155
 156         if ((hl = ntohs(*(u16 *) (p + 2))) > l)
 157         {
 158                 log(1, 0, s, t, "Length mismatch CHAP %u/%u\n", hl, l);
 159                 STAT(tunnel_rx_errors);
 160                 return ;
 161         }
 162         l = hl;
 163
 164         if (*p != 2)
 165         {
 166                 log(1, 0, s, t, "Unexpected CHAP response code %d\n", *p);
 167                 STAT(tunnel_rx_errors);
 168                 return;
 169         }
 170         if (p[1] != radius[r].id)
 171         {
 172                 log(1, 0, s, t, "Wrong CHAP response ID %d (should be %d) (%d)\n", p[1], radius[r].id, r);
 173                 STAT(tunnel_rx_errors);
 174                 return ;
 175         }
 176
 177         if (l < 5 || p[4] != 16)
 178         {
 179                 log(1, 0, s, t, "Bad CHAP response length %d\n", l < 5 ? -1 : p[4]);
 180                 STAT(tunnel_rx_errors);
 181                 return ;
 182         }
 183
 184         l -= 5;
 185         p += 5;
 186         if (l < 16 || l - 16 >= sizeof(session[s].user))
 187         {
 188                 log(1, 0, s, t, "CHAP user too long %d\n", l - 16);
 189                 STAT(tunnel_rx_errors);
 190                 return ;
 191         }
 192
 193         // Run PRE_AUTH plugins
 194         {
 195                 struct param_pre_auth packet = { &tunnel[t], &session[s], NULL, NULL, PPPCHAP, 1 };
 196
 197                 packet.password = calloc(17, 1);
 198                 memcpy(packet.password, p, 16);
 199
 200                 p += 16;
 201                 l -= 16;
 202
 203                 packet.username = calloc(l + 1, 1);
 204                 memcpy(packet.username, p, l);
 205
 206                 run_plugins(PLUGIN_PRE_AUTH, &packet);
 207                 if (!packet.continue_auth)
 208                 {
 209                         log(3, 0, s, t, "A plugin rejected PRE_AUTH\n");
 210                         if (packet.username) free(packet.username);
 211                         if (packet.password) free(packet.password);
 212                         return;
 213                 }
 214
 215                 strncpy(session[s].user, packet.username, sizeof(session[s].user) - 1);
 216                 memcpy(radius[r].pass, packet.password, 16);
 217
 218                 free(packet.username);
 219                 free(packet.password);
 220         }
 221
 222         radius[r].chap = 1;
 223         log(3, 0, s, t, "CHAP login %s\n", session[s].user);
 224         radiussend(r, RADIUSAUTH);
 225 }
 226
 227 char *ppp_lcp_types[] = {
 228         NULL,
 229         "ConfigReq",
 230         "ConfigAck",
 231         "ConfigNak",
 232         "ConfigRej",
 233         "TerminateReq",
 234         "TerminateAck",
 235         "CodeRej",
 236         "ProtocolRej",
 237         "EchoReq",
 238         "EchoReply",
 239         "DiscardRequest",
 240         "IdentRequest",
 241 };
 242
 243 void dumplcp(u8 *p, int l)
 244 {
 245         int x = l - 4;
 246         u8 *o = (p + 4);
 247
 248         log_hex(5, "PPP LCP Packet", p, l);
 249         log(4, 0, 0, 0, "PPP LCP Packet type %d (%s len %d)\n", *p, ppp_lcp_types[(int)*p], ntohs( ((u16 *) p)[1]) );
 250         log(4, 0, 0, 0, "Length: %d\n", l);
 251         if (*p != ConfigReq && *p != ConfigRej && *p != ConfigAck)
 252                 return;
 253
 254         while (x > 2)
 255         {
 256                 int type = o[0];
 257                 int length = o[1];
 258                 if (length < 2)
 259                 {
 260                         log(4, 0, 0, 0, "       Option length is %d...\n", length);
 261                         break;
 262                 }
 263                 if (type == 0)
 264                 {
 265                         log(4, 0, 0, 0, "       Option type is 0...\n");
 266                         x -= length;
 267                         o += length;
 268                         continue;
 269                 }
 270                 switch (type)
 271                 {
 272                         case 1: // Maximum-Receive-Unit
 273                                 if (length == 4)
 274                                         log(4, 0, 0, 0, "    %s %d\n", lcp_types[type], ntohs(*(u16 *)(o + 2)));
 275                                 else
 276                                         log(4, 0, 0, 0, "    %s odd length %d\n", lcp_types[type], length);
 277                                 break;
 278                         case 3: // Authentication-Protocol
 279                                 {
 280                                         if (length == 4)
 281                                         {
 282                                                 int proto = ntohs(*(u16 *)(o + 2));
 283                                                 log(4, 0, 0, 0, "   %s 0x%x (%s)\n", lcp_types[type], proto,
 284                                                         proto == PPPCHAP ? "CHAP" :
 285                                                         proto == PPPPAP  ? "PAP"  : "UNKNOWN");
 286                                         }
 287                                         else
 288                                                 log(4, 0, 0, 0, "   %s odd length %d\n", lcp_types[type], length);
 289                                         break;
 290                                 }
 291                         case 4: // Quality-Protocol
 292                                 {
 293                                         u32 qp = ntohl(*(u32 *)(o + 2));
 294                                         log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], qp);
 295                                         break;
 296                                 }
 297                         case 5: // Magic-Number
 298                                 {
 299                                         if (length == 6)
 300                                         {
 301                                                 u32 magicno = ntohl(*(u32 *)(o + 2));
 302                                                 log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], magicno);
 303                                         }
 304                                         else
 305                                                 log(4, 0, 0, 0, "   %s odd length %d\n", lcp_types[type], length);
 306                                         break;
 307                                 }
 308                         case 7: // Protocol-Field-Compression
 309                                 {
 310                                         log(4, 0, 0, 0, "    %s\n", lcp_types[type]);
 311                                         break;
 312                                 }
 313                         case 8: // Address-And-Control-Field-Compression
 314                                 {
 315                                         log(4, 0, 0, 0, "    %s\n", lcp_types[type]);
 316                                         break;
 317                                 }
 318                         default:
 319                                 log(2, 0, 0, 0, "    Unknown PPP LCP Option type %d\n", type);
 320                                 break;
 321                 }
 322                 x -= length;
 323                 o += length;
 324         }
 325 }
 326
 327 // Process LCP messages
 328 void processlcp(tunnelidt t, sessionidt s, u8 *p, u16 l)
 329 {
 330         u8 b[MAXCONTROL];
 331         u8 *q = NULL;
 332         u32 magicno = 0;
 333         u16 hl;
 334
 335         CSTAT(call_processlcp);
 336
 337         log_hex(5, "LCP", p, l);
 338         if (l < 4)
 339         {
 340                 log(1, session[s].ip, s, t, "Short LCP %d bytes\n", l);
 341                 STAT(tunnel_rx_errors);
 342                 return ;
 343         }
 344
 345         if ((hl = ntohs(*(u16 *) (p + 2))) > l)
 346         {
 347                 log(1, 0, s, t, "Length mismatch LCP %u/%u\n", hl, l);
 348                 STAT(tunnel_rx_errors);
 349                 return ;
 350         }
 351         l = hl;
 352
 353         if (*p == ConfigAck)
 354         {
 355                 log(3, session[s].ip, s, t, "LCP: Discarding ConfigAck\n");
 356                 session[s].flags |= SESSIONLCPACK;
 357         }
 358         else if (*p == ConfigReq)
 359         {
 360                 int x = l - 4;
 361                 u8 *o = (p + 4);
 362
 363                 log(3, session[s].ip, s, t, "LCP: ConfigReq (%d bytes)...\n", l);
 364                 if (config->debug > 3) dumplcp(p, l);
 365
 366                 while (x > 2)
 367                 {
 368                         int type = o[0];
 369                         int length = o[1];
 370                         if (length == 0 || type == 0) break;
 371                         switch (type)
 372                         {
 373                                 case 1: // Maximum-Receive-Unit
 374                                         session[s].mru = ntohs(*(u16 *)(o + 2));
 375                                         break;
 376                                 case 2: // asyncmap
 377                                         log_hex(2, "PPP LCP Packet", p, l);
 378                                         log(2, 0, 0, 0, "PPP LCP Packet type %d (%s len %d)\n", *p, ppp_lcp_types[(int)*p], ntohs( ((u16 *) p)[1]) );
 379                                         break;
 380                                 case 3: // Authentication-Protocol
 381                                         {
 382                                                 int proto = ntohs(*(u16 *)(o + 2));
 383                                                 if (proto == PPPCHAP)
 384                                                 {
 385                                                         log(2, session[s].ip, s, t, "    Remote end is trying to do CHAP. Rejecting it.\n");
 386
 387                                                         if (!q)
 388                                                         {
 389                                                                 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 390                                                                 if (!q) {
 391                                                                         log(2, session[s].ip, s, t, " Failed to send packet.\n");
 392                                                                         break;
 393                                                                 }
 394                                                                 *q++ = ConfigNak;
 395                                                         }
 396                                                         memcpy(q, o, length);
 397                                                         *(u16 *)(q += 2) = htons(PPPPAP); // NAK -> Use PAP instead
 398                                                         q += length;
 399                                                 }
 400                                                 break;
 401                                         }
 402                                 case 5: // Magic-Number
 403                                         {
 404                                                 magicno = ntohl(*(u32 *)(o + 2));
 405                                                 break;
 406                                         }
 407                                 case 4: // Quality-Protocol
 408                                 case 7: // Protocol-Field-Compression
 409                                 case 8: // Address-And-Control-Field-Compression
 410                                                 break;
 411                                 case 13: // CallBack option for LCP extention of win2000/routers L2TP client
 412                                 case 17:
 413                                 case 18:
 414                                 {
 415                                         // Reject LCP CallBack
 416                                         log(2, session[s].ip, s, t, "    PPP LCP Option type %d, len=%d\n", type, length);
 417                                         memcpy(p + 4, o, length);
 418                                         *(u16 *)(p + 2) = htons(length + 4);
 419                                         *p = ConfigRej;
 420                                         q = makeppp(b,sizeof(b), p, length + 4, t, s, PPPLCP);
 421                                         tunnelsend(b, 12 + length + 4, t);
 422                                         return;
 423                                         }
 424
 425                                 default:
 426                                         // Reject Unknown LCP Option to stop to send it again
 427                                         log(2, session[s].ip, s, t, "    Unknown PPP LCP Option type %d\n", type);
 428                                         memcpy(p + 4, o, length);
 429                                         *(u16 *)(p + 2) = htons(length + 4);
 430                                         *p = ConfigRej;
 431                                         q = makeppp(b,sizeof(b), p, length + 4, t, s, PPPLCP);
 432                                         tunnelsend(b, 12 + length + 4, t);
 433                                         return;
 434                         }
 435                         x -= length;
 436                         o += length;
 437                 }
 438
 439                 if (!q)
 440                 {
 441                         // Send back a ConfigAck
 442                         log(3, session[s].ip, s, t, "ConfigReq accepted, sending as Ack\n");
 443                         // for win2k L2TP clients and LCP renegotiation of alive session
 444                         if (magicno || l == 4 || (session[s].mru && l == 8)) initlcp(t, s);
 445                         q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 446                         if (!q)
 447                         {
 448                                 log(3, session[s].ip, s, t, " failed to create packet.\n");
 449                                 return;
 450                         }
 451                         *q = ConfigAck;
 452                         tunnelsend(b, l + (q - b), t);
 453                 }
 454                 else
 455                 {
 456                         // Already built a ConfigNak... send it
 457                         log(3, session[s].ip, s, t, "Sending ConfigNak\n");
 458                         tunnelsend(b, l + (q - b), t);
 459                 }
 460
 461                 if (!(session[s].flags & SESSIONLCPACK))
 462                         initlcp(t, s);
 463         }
 464         else if (*p == ConfigNak)
 465         {
 466                 log(1, session[s].ip, s, t, "Remote end sent a ConfigNak. Ignoring\n");
 467                 if (config->debug > 3) dumplcp(p, l);
 468                 return ;
 469         }
 470         else if (*p == TerminateReq)
 471         {
 472                 *p = TerminateAck;      // close
 473                 q = makeppp(b, sizeof(b),  p, l, t, s, PPPLCP);
 474                 if (!q) {
 475                         log(3, session[s].ip, s, t, "Failed to create PPP packet in processlcp.\n");
 476                         return;
 477                 }
 478                 log(3, session[s].ip, s, t, "LCP: Received TerminateReq. Sending TerminateAck\n");
 479                 sessionshutdown(s, "Remote end closed connection.");
 480                 tunnelsend(b, l + (q - b), t); // send it
 481         }
 482         else if (*p == TerminateAck)
 483         {
 484                 sessionshutdown(s, "Connection closed.");
 485         }
 486         else if (*p == EchoReq)
 487         {
 488                 *p = EchoReply;         // reply
 489                 *(u32 *) (p + 4) = htonl(session[s].magic); // our magic number
 490                 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 491                 if (!q) {
 492                         log(3, session[s].ip, s, t, " failed to send EchoReply.\n");
 493                         return;
 494                 }
 495                 log(5, session[s].ip, s, t, "LCP: Received EchoReq. Sending EchoReply\n");
 496                 tunnelsend(b, l + (q - b), t); // send it
 497         }
 498         else if (*p == EchoReply)
 499         {
 500                 // Ignore it, last_packet time is set earlier than this.
 501         }
 502         else if (*p == IdentRequest)
 503         {
 504                 *p = CodeRej;
 505                 if (l > MAXCONTROL)
 506                 {
 507                         log(1, 0, s, t, "Truncated Ident Packet (length=%d) to 1400 bytes\n", l);
 508                         l = 1400;
 509                 }
 510                 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 511                 if (!q)
 512                 {
 513                         log(3, session[s].ip, s, t, "Failed to create IdentRej.\n");
 514                         return;
 515                 }
 516                 log_hex(5, "LCPIdentRej", q, l + 4);
 517                 tunnelsend(b, 12 + 4 + l, t);
 518         }
 519         else
 520         {
 521                 log(1, session[s].ip, s, t, "Unexpected LCP code %d\n", *p);
 522                 STAT(tunnel_rx_errors);
 523                 return ;
 524         }
 525 }
 526
 527 // Process IPCP messages
 528 void processipcp(tunnelidt t, sessionidt s, u8 *p, u16 l)
 529 {
 530         u16 hl;
 531
 532         CSTAT(call_processipcp);
 533
 534         log_hex(5, "IPCP", p, l);
 535         if (l < 5)
 536         {
 537                 log(1, 0, s, t, "Short IPCP %d bytes\n", l);
 538                 STAT(tunnel_rx_errors);
 539                 return ;
 540         }
 541
 542         if ((hl = ntohs(*(u16 *) (p + 2))) > l)
 543         {
 544                 log(1, 0, s, t, "Length mismatch IPCP %u/%u\n", hl, l);
 545                 STAT(tunnel_rx_errors);
 546                 return ;
 547         }
 548         l = hl;
 549
 550         if (*p == ConfigAck)
 551         {
 552                 // happy with our IPCP
 553                 u16 r = session[s].radius;
 554                 if ((!r || radius[r].state == RADIUSIPCP) && !session[s].walled_garden)
 555                 {
 556                         if (!r)
 557                                 r = radiusnew(s);
 558                         if (r)
 559                                 radiussend(r, RADIUSSTART); // send radius start, having got IPCP at last
 560                 }
 561                 session[s].flags |= SF_IPCP_ACKED;
 562
 563                 log(3, session[s].ip, s, t, "IPCP Acked, session is now active\n");
 564                 return;
 565         }
 566         if (*p != ConfigReq)
 567         {
 568                 log(1, 0, s, t, "Unexpected IPCP code %d\n", *p);
 569                 STAT(tunnel_rx_errors);
 570                 return ;
 571         }
 572         log(4, session[s].ip, s, t, "IPCP ConfigReq received\n");
 573
 574         if (!session[s].ip)
 575         {
 576                 log(3, 0, s, t, "Waiting on radius reply\n");
 577                 return;                 // have to wait on RADIUS reply
 578         }
 579         // form a config reply quoting the IP in the session
 580         {
 581                 u8 b[MAXCONTROL];
 582                 u8 *i,
 583                 *q;
 584
 585                 q = p + 4;
 586                 i = p + l;
 587                 while (q < i && q[1])
 588                 {
 589                         if (*q != 0x81 && *q != 0x83 && *q != 3)
 590                                 break;
 591                         q += q[1];
 592                 }
 593                 if (q < i)
 594                 {
 595                         // reject
 596                         u16 n = 4;
 597                         i = p + l;
 598                         if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP)))
 599                         {
 600                                 log(2, 0, s, t, "Failed to send IPCP ConfigRej\n");
 601                                 return;
 602                         }
 603                         *q = ConfigRej;
 604                         p += 4;
 605                         while (p < i && p[1])
 606                         {
 607                                 if (*p != 0x81 && *p != 0x83 && *p != 3)
 608                                 {
 609                                         log(2, 0, s, t, "IPCP reject %d\n", *p);
 610                                         memcpy(q + n, p, p[1]);
 611                                         n += p[1];
 612                                 }
 613                                 p += p[1];
 614                         }
 615                         *(u16 *) (q + 2) = htons(n);
 616                         log(4, session[s].ip, s, t, "Sending ConfigRej\n");
 617                         tunnelsend(b, n + (q - b), t); // send it
 618                 }
 619                 else
 620                 {
 621                         log(4, session[s].ip, s, t, "Sending ConfigAck\n");
 622                         *p = ConfigAck;
 623                         if ((i = findppp(p, 0x81))) // Primary DNS address
 624                         {
 625                                 if (*(u32 *) (i + 2) != htonl(session[s].dns1))
 626                                 {
 627                                         *(u32 *) (i + 2) = htonl(session[s].dns1);
 628                                         *p = ConfigNak;
 629                                         log(5, session[s].ip, s, t, "   DNS1 = %s\n", inet_toa(session[s].dns1));
 630                                 }
 631                         }
 632                         if ((i = findppp(p, 0x83))) // Secondary DNS address (TBA, is it)
 633                         {
 634                                 if (*(u32 *) (i + 2) != htonl(session[s].dns2))
 635                                 {
 636                                         *(u32 *) (i + 2) = htonl(session[s].dns2);
 637                                         *p = ConfigNak;
 638                                         log(5, session[s].ip, s, t, "   DNS2 = %s\n", inet_toa(session[s].dns1));
 639                                 }
 640                         }
 641                         i = findppp(p, 3);              // IP address
 642                         if (!i || i[1] != 6)
 643                         {
 644                                 log(1, 0, s, t, "No IP in IPCP request\n");
 645                                 STAT(tunnel_rx_errors);
 646                                 return ;
 647                         }
 648                         if (*(u32 *) (i + 2) != htonl(session[s].ip))
 649                         {
 650                                 *(u32 *) (i + 2) = htonl(session[s].ip);
 651                                 *p = ConfigNak;
 652                                 log(4, session[s].ip, s, t, " No, a ConfigNak, client is requesting IP - sending %s\n",
 653                                                 inet_toa(htonl(session[s].ip)));
 654                         }
 655                         if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP)))
 656                         {
 657                                 log(2, 0, s, t, " Failed to send IPCP packet.\n");
 658                                 return;
 659                         }
 660                         tunnelsend(b, l + (q - b), t); // send it
 661                 }
 662         }
 663 }
 664
 665 // process IP packet received
 666 //
 667 // This MUST be called with at least 4 byte behind 'p'.
 668 // (i.e. this routine writes to p[-4]).
 669 void processipin(tunnelidt t, sessionidt s, u8 *p, u16 l)
 670 {
 671         ipt ip;
 672
 673         CSTAT(call_processipin);
 674
 675         log_hex(5, "IP", p, l);
 676
 677         ip = ntohl(*(u32 *)(p + 12));
 678
 679         if (l > MAXETHER)
 680         {
 681                 log(1, ip, s, t, "IP packet too long %d\n", l);
 682                 STAT(tunnel_rx_errors);
 683                 return ;
 684         }
 685
 686         // no spoof (do sessionbyip to handled statically routed subnets)
 687         if (ip != session[s].ip && sessionbyip(htonl(ip)) != s)
 688         {
 689                 log(5, ip, s, t, "Dropping packet with spoofed IP %s\n", inet_toa(htonl(ip)));
 690                 return;
 691         }
 692
 693         if (session[s].snoop_ip && session[s].snoop_port)
 694         {
 695                 // Snooping this session
 696                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
 697         }
 698
 699         // Add on the tun header
 700         p -= 4;
 701         *(u32 *)p = htonl(0x00000800);
 702         l += 4;
 703
 704         if (session[s].tbf_in && !config->cluster_iam_master) { // Are we throttled and a slave?
 705                 master_throttle_packet(session[s].tbf_in, p, l); // Pass it to the master for handling.
 706                 return;
 707         }
 708
 709         session[s].cin += l - 4;
 710         session[s].total_cin += l - 4;
 711         sess_count[s].cin += l - 4;
 712
 713         session[s].pin++;
 714         eth_tx += l - 4;
 715
 716         STAT(tun_tx_packets);
 717         INC_STAT(tun_tx_bytes, l);
 718
 719         if (session[s].tbf_in && config->cluster_iam_master) { // Are we throttled and a master?? actually handle the throttled packets.
 720                 tbf_queue_packet(session[s].tbf_in, p, l);
 721                 return;
 722         }
 723
 724         // send to ethernet
 725         if (tun_write(p, l) < 0)
 726         {
 727                 STAT(tun_tx_errors);
 728                 log(0, 0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
 729                         l, strerror(errno), tunfd, p);
 730         }
 731
 732 }
 733
 734 //
 735 // Helper routine for the TBF filters.
 736 // Used to send queued data in from the user.
 737 //
 738 void send_ipin(sessionidt s, u8 *buf, int len)
 739 {
 740         log_hex(5, "IP in throttled", buf, len);
 741         if (write(tunfd, buf, len) < 0)
 742         {
 743                 STAT(tun_tx_errors);
 744                 log(0, 0, 0, 0, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
 745                         len, strerror(errno), tunfd, buf);
 746         }
 747
 748         // Increment packet counters
 749         session[s].cin += len - 4;
 750         session[s].total_cin += len - 4;
 751         sess_count[s].cin += len - 4;
 752
 753         session[s].pin++;
 754         eth_tx += len - 4;
 755 }
 756
 757
 758 // Process LCP messages
 759 void processccp(tunnelidt t, sessionidt s, u8 *p, u16 l)
 760 {
 761
 762         CSTAT(call_processccp);
 763
 764         log_hex(5, "CCP", p, l);
 765         if (l < 2 || (*p != ConfigReq && *p != TerminateReq))
 766         {
 767                 log(1, 0, s, t, "Unexpected CCP request code %d\n", *p);
 768                 STAT(tunnel_rx_errors);
 769                 return ;
 770         }
 771         // reject
 772         {
 773                 u8 b[MAXCONTROL];
 774                 u8 *q;
 775                 if (*p == ConfigReq)
 776                 {
 777                         if (l < 6)
 778                         {
 779                                 *p = ConfigAck;         // accept no compression
 780                         }
 781                         else
 782                         {
 783                                 *p = ConfigRej;         // reject
 784                                 sendccp(t, s);
 785                         }
 786                 }
 787                 else
 788                         *p = TerminateAck;              // close
 789                 if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPCCP)))
 790                 {
 791                         log(1,0,0,0, "Failed to send CCP packet.\n");
 792                         return;
 793                 }
 794                 tunnelsend(b, l + (q - b), t); // send it
 795         }
 796 }
 797
 798 // send a CHAP PP packet
 799 void sendchap(tunnelidt t, sessionidt s)
 800 {
 801         u8 b[MAXCONTROL];
 802         u16 r = session[s].radius;
 803         u8 *q;
 804
 805         CSTAT(call_sendchap);
 806
 807         if (!r)
 808         {
 809                 log(1, 0, s, t, "No RADIUS to send challenge\n");
 810                 STAT(tunnel_tx_errors);
 811                 return ;
 812         }
 813         log(1, 0, s, t, "Send CHAP challenge\n");
 814         {
 815                 // new challenge
 816                 int n;
 817                 for (n = 0; n < 15; n++)
 818                         radius[r].auth[n] = rand();
 819         }
 820         radius[r].chap = 1;             // CHAP not PAP
 821         radius[r].id++;
 822         if (radius[r].state != RADIUSCHAP)
 823                 radius[r].try = 0;
 824         radius[r].state = RADIUSCHAP;
 825         radius[r].retry = backoff(radius[r].try++);
 826         if (radius[r].try > 5)
 827         {
 828                 sessionshutdown(s, "Timeout CHAP");
 829                 STAT(tunnel_tx_errors);
 830                 return ;
 831         }
 832         q = makeppp(b, sizeof(b), 0, 0, t, s, PPPCHAP);
 833         if (!q) {
 834                 log(1, 0, s, t, "failed to send CHAP challenge.\n");
 835                 return;
 836         }
 837         *q = 1;                                 // challenge
 838         q[1] = radius[r].id;                    // ID
 839         q[4] = 16;                              // length
 840         memcpy(q + 5, radius[r].auth, 16);      // challenge
 841         strcpy(q + 21, hostname);               // our name
 842         *(u16 *) (q + 2) = htons(strlen(hostname) + 21); // length
 843         tunnelsend(b, strlen(hostname) + 21 + (q - b), t); // send it
 844 }
 845
 846 // fill in a L2TP message with a PPP frame,
 847 // copies existing PPP message and changes magic number if seen
 848 // returns start of PPP frame
 849 u8 *makeppp(u8 *b, int size, u8 *p, int l, tunnelidt t, sessionidt s, u16 mtype)
 850 {
 851         if (size < 12)
 852                 return NULL;    // Need more space than this!!
 853
 854         *(u16 *) (b + 0) = htons(0x0002); // L2TP with no options
 855         *(u16 *) (b + 2) = htons(tunnel[t].far); // tunnel
 856         *(u16 *) (b + 4) = htons(session[s].far); // session
 857         b += 6;
 858         if (mtype == PPPLCP || !(session[s].l2tp_flags & SESSIONACFC))
 859         {
 860                 *(u16 *) b = htons(0xFF03); // HDLC header
 861                 b += 2;
 862         }
 863         if (mtype < 0x100 && session[s].l2tp_flags & SESSIONPFC)
 864                 *b++ = mtype;
 865         else
 866         {
 867                 *(u16 *) b = htons(mtype);
 868                 b += 2;
 869         }
 870
 871         if (l + 12 > size) {
 872                 log(3,0,0,0, "Would have overflowed the buffer in makeppp: size %d, len %d.\n", size, l);
 873                 return NULL;    // Run out of room to hold the packet!
 874         }
 875         if (p && l)
 876                 memcpy(b, p, l);
 877         return b;
 878 }
 879
 880 // find a PPP option, returns point to option, or 0 if not found
 881 u8 *findppp(u8 *b, u8 mtype)
 882 {
 883         u16 l = ntohs(*(u16 *) (b + 2));
 884         if (l < 4)
 885                 return 0;
 886         b += 4;
 887         l -= 4;
 888         while (l)
 889         {
 890                 if (l < b[1] || !b[1])
 891                         return 0;               // faulty
 892                 if (*b == mtype)
 893                         return b;
 894                 l -= b[1];
 895                 b += b[1];
 896         }
 897         return 0;
 898 }
 899
 900 // Send initial LCP ConfigReq
 901 void initlcp(tunnelidt t, sessionidt s)
 902 {
 903         char b[500] = {0}, *q;
 904
 905         q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPLCP);
 906         if (!q) {
 907                 log(1, 0, s, t, "Failed to send LCP ConfigReq.\n");
 908                 return;
 909         }
 910         log(4, 0, s, t, "Sending LCP ConfigReq for PAP\n");
 911         *q = ConfigReq;
 912         *(u8 *)(q + 1) = (time_now % 255) + 1; // ID
 913         *(u16 *)(q + 2) = htons(14); // Length
 914         *(u8 *)(q + 4) = 5;
 915         *(u8 *)(q + 5) = 6;
 916         *(u32 *)(q + 6) = htonl(session[s].magic);
 917         *(u8 *)(q + 10) = 3;
 918         *(u8 *)(q + 11) = 4;
 919         *(u16 *)(q + 12) = htons(PPPPAP); // PAP
 920         tunnelsend(b, 12 + 14, t);
 921 }
 922
 923 // Send CCP reply
 924 void sendccp(tunnelidt t, sessionidt s)
 925 {
 926         char *q, b[500] = {0};
 927
 928         q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPCCP);
 929         *q = ConfigReq;
 930         *(u8 *)(q + 1) = (time_now % 255) + 1; // ID
 931         *(u16 *)(q + 2) = htons(4); // Length
 932         log_hex(5, "PPPCCP", q, 4);
 933         tunnelsend(b, (q - b) + 4 , t);
 934 }
 935