ppp.c

   1 // L2TPNS PPP Stuff
   2
   3 char const *cvs_id_ppp = "$Id: ppp.c,v 1.18 2004-11-03 13:22:39 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.username = calloc(l - 16 + 1, 1);
 198                 packet.password = calloc(16, 1);
 199                 memcpy(packet.username, p + 16, l - 16);
 200                 memcpy(packet.password, p, 16);
 201
 202                 run_plugins(PLUGIN_PRE_AUTH, &packet);
 203                 if (!packet.continue_auth)
 204                 {
 205                         log(3, 0, s, t, "A plugin rejected PRE_AUTH\n");
 206                         if (packet.username) free(packet.username);
 207                         if (packet.password) free(packet.password);
 208                         return;
 209                 }
 210
 211                 strncpy(session[s].user, packet.username, sizeof(session[s].user) - 1);
 212                 memcpy(radius[r].pass, packet.password, 16);
 213
 214                 free(packet.username);
 215                 free(packet.password);
 216         }
 217
 218         radius[r].chap = 1;
 219         log(3, 0, s, t, "CHAP login %s\n", session[s].user);
 220         radiussend(r, RADIUSAUTH);
 221 }
 222
 223 char *ppp_lcp_types[] = {
 224         NULL,
 225         "ConfigReq",
 226         "ConfigAck",
 227         "ConfigNak",
 228         "ConfigRej",
 229         "TerminateReq",
 230         "TerminateAck",
 231         "CodeRej",
 232         "ProtocolRej",
 233         "EchoReq",
 234         "EchoReply",
 235         "DiscardRequest",
 236         "IdentRequest",
 237 };
 238
 239 void dumplcp(u8 *p, int l)
 240 {
 241         int x = l - 4;
 242         u8 *o = (p + 4);
 243
 244         log_hex(5, "PPP LCP Packet", p, l);
 245         log(4, 0, 0, 0, "PPP LCP Packet type %d (%s len %d)\n", *p, ppp_lcp_types[(int)*p], ntohs( ((u16 *) p)[1]) );
 246         log(4, 0, 0, 0, "Length: %d\n", l);
 247         if (*p != ConfigReq && *p != ConfigRej && *p != ConfigAck)
 248                 return;
 249
 250         while (x > 2)
 251         {
 252                 int type = o[0];
 253                 int length = o[1];
 254                 if (length < 2)
 255                 {
 256                         log(4, 0, 0, 0, "       Option length is %d...\n", length);
 257                         break;
 258                 }
 259                 if (type == 0)
 260                 {
 261                         log(4, 0, 0, 0, "       Option type is 0...\n");
 262                         x -= length;
 263                         o += length;
 264                         continue;
 265                 }
 266                 switch (type)
 267                 {
 268                         case 1: // Maximum-Receive-Unit
 269                                 if (length == 4)
 270                                         log(4, 0, 0, 0, "    %s %d\n", lcp_types[type], ntohs(*(u16 *)(o + 2)));
 271                                 else
 272                                         log(4, 0, 0, 0, "    %s odd length %d\n", lcp_types[type], length);
 273                                 break;
 274                         case 3: // Authentication-Protocol
 275                                 {
 276                                         if (length == 4)
 277                                         {
 278                                                 int proto = ntohs(*(u16 *)(o + 2));
 279                                                 log(4, 0, 0, 0, "   %s 0x%x (%s)\n", lcp_types[type], proto,
 280                                                         proto == 0xC223 ? "CHAP" :
 281                                                         proto == 0xC023 ? "PAP"  : "UNKNOWN");
 282                                         }
 283                                         else
 284                                                 log(4, 0, 0, 0, "   %s odd length %d\n", lcp_types[type], length);
 285                                         break;
 286                                 }
 287                         case 4: // Quality-Protocol
 288                                 {
 289                                         u32 qp = ntohl(*(u32 *)(o + 2));
 290                                         log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], qp);
 291                                         break;
 292                                 }
 293                         case 5: // Magic-Number
 294                                 {
 295                                         if (length == 6)
 296                                         {
 297                                                 u32 magicno = ntohl(*(u32 *)(o + 2));
 298                                                 log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], magicno);
 299                                         }
 300                                         else
 301                                                 log(4, 0, 0, 0, "   %s odd length %d\n", lcp_types[type], length);
 302                                         break;
 303                                 }
 304                         case 7: // Protocol-Field-Compression
 305                                 {
 306                                         log(4, 0, 0, 0, "    %s\n", lcp_types[type]);
 307                                         break;
 308                                 }
 309                         case 8: // Address-And-Control-Field-Compression
 310                                 {
 311                                         log(4, 0, 0, 0, "    %s\n", lcp_types[type]);
 312                                         break;
 313                                 }
 314                         default:
 315                                 log(2, 0, 0, 0, "    Unknown PPP LCP Option type %d\n", type);
 316                                 break;
 317                 }
 318                 x -= length;
 319                 o += length;
 320         }
 321 }
 322
 323 // Process LCP messages
 324 void processlcp(tunnelidt t, sessionidt s, u8 *p, u16 l)
 325 {
 326         u8 b[MAXCONTROL];
 327         u8 *q = NULL;
 328         u32 magicno = 0;
 329         u16 hl;
 330
 331         CSTAT(call_processlcp);
 332
 333         log_hex(5, "LCP", p, l);
 334         if (l < 4)
 335         {
 336                 log(1, session[s].ip, s, t, "Short LCP %d bytes\n", l);
 337                 STAT(tunnel_rx_errors);
 338                 return ;
 339         }
 340
 341         if ((hl = ntohs(*(u16 *) (p + 2))) > l)
 342         {
 343                 log(1, 0, s, t, "Length mismatch LCP %u/%u\n", hl, l);
 344                 STAT(tunnel_rx_errors);
 345                 return ;
 346         }
 347         l = hl;
 348
 349         if (*p == ConfigAck)
 350         {
 351                 log(3, session[s].ip, s, t, "LCP: Discarding ConfigAck\n");
 352                 session[s].flags |= SESSIONLCPACK;
 353         }
 354         else if (*p == ConfigReq)
 355         {
 356                 int x = l - 4;
 357                 u8 *o = (p + 4);
 358
 359                 log(3, session[s].ip, s, t, "LCP: ConfigReq (%d bytes)...\n", l);
 360                 if (config->debug > 3) dumplcp(p, l);
 361
 362                 while (x > 2)
 363                 {
 364                         int type = o[0];
 365                         int length = o[1];
 366                         if (length == 0 || type == 0) break;
 367                         switch (type)
 368                         {
 369                                 case 1: // Maximum-Receive-Unit
 370                                         session[s].mru = ntohs(*(u16 *)(o + 2));
 371                                         break;
 372                                 case 2: // asyncmap
 373                                         log_hex(2, "PPP LCP Packet", p, l);
 374                                         log(2, 0, 0, 0, "PPP LCP Packet type %d (%s len %d)\n", *p, ppp_lcp_types[(int)*p], ntohs( ((u16 *) p)[1]) );
 375                                         break;
 376                                 case 3: // Authentication-Protocol
 377                                         {
 378                                                 int proto = ntohs(*(u16 *)(o + 2));
 379                                                 if (proto == 0xC223)
 380                                                 {
 381                                                         log(2, session[s].ip, s, t, "    Remote end is trying to do CHAP. Rejecting it.\n");
 382
 383                                                         if (!q)
 384                                                         {
 385                                                                 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 386                                                                 if (!q) {
 387                                                                         log(2, session[s].ip, s, t, " Failed to send packet.\n");
 388                                                                         break;
 389                                                                 }
 390                                                                 *q++ = ConfigNak;
 391                                                         }
 392                                                         memcpy(q, o, length);
 393                                                         *(u16 *)(q += 2) = htons(0xC023); // NAK -> Use PAP instead
 394                                                         q += length;
 395                                                 }
 396                                                 break;
 397                                         }
 398                                 case 5: // Magic-Number
 399                                         {
 400                                                 magicno = ntohl(*(u32 *)(o + 2));
 401                                                 break;
 402                                         }
 403                                 case 4: // Quality-Protocol
 404                                 case 7: // Protocol-Field-Compression
 405                                 case 8: // Address-And-Control-Field-Compression
 406                                                 break;
 407                                 case 13: // CallBack option for LCP extention of win2000/routers L2TP client
 408                                 case 17:
 409                                 case 18:
 410                                 {
 411                                         // Reject LCP CallBack
 412                                         log(2, session[s].ip, s, t, "    PPP LCP Option type %d, len=%d\n", type, length);
 413                                         memcpy(p + 4, o, length);
 414                                         *(u16 *)(p + 2) = htons(length + 4);
 415                                         *p = ConfigRej;
 416                                         q = makeppp(b,sizeof(b), p, length + 4, t, s, PPPLCP);
 417                                         tunnelsend(b, 12 + length + 4, t);
 418                                         return;
 419                                         }
 420
 421                                 default:
 422                                         // Reject Unknown LCP Option to stop to send it again
 423                                         log(2, session[s].ip, s, t, "    Unknown PPP LCP Option type %d\n", type);
 424                                         memcpy(p + 4, o, length);
 425                                         *(u16 *)(p + 2) = htons(length + 4);
 426                                         *p = ConfigRej;
 427                                         q = makeppp(b,sizeof(b), p, length + 4, t, s, PPPLCP);
 428                                         tunnelsend(b, 12 + length + 4, t);
 429                                         return;
 430                         }
 431                         x -= length;
 432                         o += length;
 433                 }
 434
 435                 if (!q)
 436                 {
 437                         // Send back a ConfigAck
 438                         log(3, session[s].ip, s, t, "ConfigReq accepted, sending as Ack\n");
 439                         // for win2k L2TP clients and LCP renegotiation of alive session
 440                         if (magicno || l == 4 || (session[s].mru && l == 8)) initlcp(t, s);
 441                         q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 442                         if (!q)
 443                         {
 444                                 log(3, session[s].ip, s, t, " failed to create packet.\n");
 445                                 return;
 446                         }
 447                         *q = ConfigAck;
 448                         tunnelsend(b, l + (q - b), t);
 449                 }
 450                 else
 451                 {
 452                         // Already built a ConfigNak... send it
 453                         log(3, session[s].ip, s, t, "Sending ConfigNak\n");
 454                         tunnelsend(b, l + (q - b), t);
 455                 }
 456
 457                 if (!(session[s].flags & SESSIONLCPACK))
 458                         initlcp(t, s);
 459         }
 460         else if (*p == ConfigNak)
 461         {
 462                 log(1, session[s].ip, s, t, "Remote end sent a ConfigNak. Ignoring\n");
 463                 if (config->debug > 3) dumplcp(p, l);
 464                 return ;
 465         }
 466         else if (*p == TerminateReq)
 467         {
 468                 *p = TerminateAck;      // close
 469                 q = makeppp(b, sizeof(b),  p, l, t, s, PPPLCP);
 470                 if (!q) {
 471                         log(3, session[s].ip, s, t, "Failed to create PPP packet in processlcp.\n");
 472                         return;
 473                 }
 474                 log(3, session[s].ip, s, t, "LCP: Received TerminateReq. Sending TerminateAck\n");
 475                 sessionshutdown(s, "Remote end closed connection.");
 476                 tunnelsend(b, l + (q - b), t); // send it
 477         }
 478         else if (*p == TerminateAck)
 479         {
 480                 sessionshutdown(s, "Connection closed.");
 481         }
 482         else if (*p == EchoReq)
 483         {
 484                 *p = EchoReply;         // reply
 485                 *(u32 *) (p + 4) = htonl(session[s].magic); // our magic number
 486                 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 487                 if (!q) {
 488                         log(3, session[s].ip, s, t, " failed to send EchoReply.\n");
 489                         return;
 490                 }
 491                 log(5, session[s].ip, s, t, "LCP: Received EchoReq. Sending EchoReply\n");
 492                 tunnelsend(b, l + (q - b), t); // send it
 493         }
 494         else if (*p == EchoReply)
 495         {
 496                 // Ignore it, last_packet time is set earlier than this.
 497         }
 498         else if (*p == IdentRequest)
 499         {
 500                 *p = CodeRej;
 501                 if (l > MAXCONTROL)
 502                 {
 503                         log(1, 0, s, t, "Truncated Ident Packet (length=%d) to 1400 bytes\n", l);
 504                         l = 1400;
 505                 }
 506                 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 507                 if (!q)
 508                 {
 509                         log(3, session[s].ip, s, t, "Failed to create IdentRej.\n");
 510                         return;
 511                 }
 512                 log_hex(5, "LCPIdentRej", q, l + 4);
 513                 tunnelsend(b, 12 + 4 + l, t);
 514         }
 515         else
 516         {
 517                 log(1, session[s].ip, s, t, "Unexpected LCP code %d\n", *p);
 518                 STAT(tunnel_rx_errors);
 519                 return ;
 520         }
 521 }
 522
 523 // Process IPCP messages
 524 void processipcp(tunnelidt t, sessionidt s, u8 *p, u16 l)
 525 {
 526         u16 hl;
 527
 528         CSTAT(call_processipcp);
 529
 530         log_hex(5, "IPCP", p, l);
 531         if (l < 5)
 532         {
 533                 log(1, 0, s, t, "Short IPCP %d bytes\n", l);
 534                 STAT(tunnel_rx_errors);
 535                 return ;
 536         }
 537
 538         if ((hl = ntohs(*(u16 *) (p + 2))) > l)
 539         {
 540                 log(1, 0, s, t, "Length mismatch IPCP %u/%u\n", hl, l);
 541                 STAT(tunnel_rx_errors);
 542                 return ;
 543         }
 544         l = hl;
 545
 546         if (*p == ConfigAck)
 547         {
 548                 // happy with our IPCP
 549                 u16 r = session[s].radius;
 550                 if ((!r || radius[r].state == RADIUSIPCP) && !session[s].walled_garden)
 551                 {
 552                         if (!r)
 553                                 r = radiusnew(s);
 554                         if (r)
 555                                 radiussend(r, RADIUSSTART); // send radius start, having got IPCP at last
 556                 }
 557                 session[s].flags |= SF_IPCP_ACKED;
 558
 559                 log(3, session[s].ip, s, t, "IPCP Acked, session is now active\n");
 560                 return;
 561         }
 562         if (*p != ConfigReq)
 563         {
 564                 log(1, 0, s, t, "Unexpected IPCP code %d\n", *p);
 565                 STAT(tunnel_rx_errors);
 566                 return ;
 567         }
 568         log(4, session[s].ip, s, t, "IPCP ConfigReq received\n");
 569
 570         if (!session[s].ip)
 571         {
 572                 log(3, 0, s, t, "Waiting on radius reply\n");
 573                 return;                 // have to wait on RADIUS reply
 574         }
 575         // form a config reply quoting the IP in the session
 576         {
 577                 u8 b[MAXCONTROL];
 578                 u8 *i,
 579                 *q;
 580
 581                 q = p + 4;
 582                 i = p + l;
 583                 while (q < i && q[1])
 584                 {
 585                         if (*q != 0x81 && *q != 0x83 && *q != 3)
 586                                 break;
 587                         q += q[1];
 588                 }
 589                 if (q < i)
 590                 {
 591                         // reject
 592                         u16 n = 4;
 593                         i = p + l;
 594                         if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP)))
 595                         {
 596                                 log(2, 0, s, t, "Failed to send IPCP ConfigRej\n");
 597                                 return;
 598                         }
 599                         *q = ConfigRej;
 600                         p += 4;
 601                         while (p < i && p[1])
 602                         {
 603                                 if (*p != 0x81 && *p != 0x83 && *p != 3)
 604                                 {
 605                                         log(2, 0, s, t, "IPCP reject %d\n", *p);
 606                                         memcpy(q + n, p, p[1]);
 607                                         n += p[1];
 608                                 }
 609                                 p += p[1];
 610                         }
 611                         *(u16 *) (q + 2) = htons(n);
 612                         log(4, session[s].ip, s, t, "Sending ConfigRej\n");
 613                         tunnelsend(b, n + (q - b), t); // send it
 614                 }
 615                 else
 616                 {
 617                         log(4, session[s].ip, s, t, "Sending ConfigAck\n");
 618                         *p = ConfigAck;
 619                         if ((i = findppp(p, 0x81))) // Primary DNS address
 620                         {
 621                                 if (*(u32 *) (i + 2) != htonl(session[s].dns1))
 622                                 {
 623                                         *(u32 *) (i + 2) = htonl(session[s].dns1);
 624                                         *p = ConfigNak;
 625                                         log(5, session[s].ip, s, t, "   DNS1 = %s\n", inet_toa(session[s].dns1));
 626                                 }
 627                         }
 628                         if ((i = findppp(p, 0x83))) // Secondary DNS address (TBA, is it)
 629                         {
 630                                 if (*(u32 *) (i + 2) != htonl(session[s].dns2))
 631                                 {
 632                                         *(u32 *) (i + 2) = htonl(session[s].dns2);
 633                                         *p = ConfigNak;
 634                                         log(5, session[s].ip, s, t, "   DNS2 = %s\n", inet_toa(session[s].dns1));
 635                                 }
 636                         }
 637                         i = findppp(p, 3);              // IP address
 638                         if (!i || i[1] != 6)
 639                         {
 640                                 log(1, 0, s, t, "No IP in IPCP request\n");
 641                                 STAT(tunnel_rx_errors);
 642                                 return ;
 643                         }
 644                         if (*(u32 *) (i + 2) != htonl(session[s].ip))
 645                         {
 646                                 *(u32 *) (i + 2) = htonl(session[s].ip);
 647                                 *p = ConfigNak;
 648                                 log(4, session[s].ip, s, t, " No, a ConfigNak, client is requesting IP - sending %s\n",
 649                                                 inet_toa(htonl(session[s].ip)));
 650                         }
 651                         if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP)))
 652                         {
 653                                 log(2, 0, s, t, " Failed to send IPCP packet.\n");
 654                                 return;
 655                         }
 656                         tunnelsend(b, l + (q - b), t); // send it
 657                 }
 658         }
 659 }
 660
 661 // process IP packet received
 662 //
 663 // This MUST be called with at least 4 byte behind 'p'.
 664 // (i.e. this routine writes to p[-4]).
 665 void processipin(tunnelidt t, sessionidt s, u8 *p, u16 l)
 666 {
 667         ipt ip;
 668
 669         CSTAT(call_processipin);
 670
 671         log_hex(5, "IP", p, l);
 672
 673         ip = ntohl(*(u32 *)(p + 12));
 674
 675         if (l > MAXETHER)
 676         {
 677                 log(1, ip, s, t, "IP packet too long %d\n", l);
 678                 STAT(tunnel_rx_errors);
 679                 return ;
 680         }
 681
 682         // no spoof (do sessionbyip to handled statically routed subnets)
 683         if (ip != session[s].ip && sessionbyip(htonl(ip)) != s)
 684         {
 685                 log(5, ip, s, t, "Dropping packet with spoofed IP %s\n", inet_toa(htonl(ip)));
 686                 return;
 687         }
 688
 689         // Add on the tun header
 690         p -= 4;
 691         *(u32 *)p = htonl(0x00000800);
 692         l += 4;
 693
 694         if (session[s].tbf_in && !config->cluster_iam_master) { // Are we throttled and a slave?
 695                 master_throttle_packet(session[s].tbf_in, p, l); // Pass it to the master for handling.
 696                 return;
 697         }
 698
 699         session[s].cin += l - 4;
 700         session[s].total_cin += l - 4;
 701         sess_count[s].cin += l - 4;
 702
 703         session[s].pin++;
 704         eth_tx += l - 4;
 705
 706         if (session[s].snoop_ip && session[s].snoop_port)
 707         {
 708                 // Snooping this session
 709                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
 710         }
 711         STAT(tun_tx_packets);
 712         INC_STAT(tun_tx_bytes, l);
 713
 714         if (session[s].tbf_in && config->cluster_iam_master) { // Are we throttled and a master?? actually handle the throttled packets.
 715                 tbf_queue_packet(session[s].tbf_in, p, l);
 716                 return;
 717         }
 718
 719         // send to ethernet
 720         if (tun_write(p, l) < 0)
 721         {
 722                 STAT(tun_tx_errors);
 723                 log(0, 0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
 724                         l, strerror(errno), tunfd, p);
 725         }
 726
 727 }
 728
 729 //
 730 // Helper routine for the TBF filters.
 731 // Used to send queued data in from the user.
 732 //
 733 void send_ipin(sessionidt s, u8 *buf, int len)
 734 {
 735         log_hex(5, "IP in throttled", buf, len);
 736         if (write(tunfd, buf, len) < 0)
 737         {
 738                 STAT(tun_tx_errors);
 739                 log(0, 0, 0, 0, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
 740                         len, strerror(errno), tunfd, buf);
 741         }
 742
 743         // Increment packet counters
 744         session[s].cin += len - 4;
 745         session[s].total_cin += len - 4;
 746         sess_count[s].cin += len - 4;
 747
 748         session[s].pin++;
 749         eth_tx += len - 4;
 750 }
 751
 752
 753 // Process LCP messages
 754 void processccp(tunnelidt t, sessionidt s, u8 *p, u16 l)
 755 {
 756
 757         CSTAT(call_processccp);
 758
 759         log_hex(5, "CCP", p, l);
 760         if (l < 2 || (*p != ConfigReq && *p != TerminateReq))
 761         {
 762                 log(1, 0, s, t, "Unexpected CCP request code %d\n", *p);
 763                 STAT(tunnel_rx_errors);
 764                 return ;
 765         }
 766         // reject
 767         {
 768                 u8 b[MAXCONTROL];
 769                 u8 *q;
 770                 if (*p == ConfigReq)
 771                 {
 772                         if (l < 6)
 773                         {
 774                                 *p = ConfigAck;         // accept no compression
 775                         }
 776                         else
 777                         {
 778                                 *p = ConfigRej;         // reject
 779                                 sendccp(t, s);
 780                         }
 781                 }
 782                 else
 783                         *p = TerminateAck;              // close
 784                 if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPCCP)))
 785                 {
 786                         log(1,0,0,0, "Failed to send CCP packet.\n");
 787                         return;
 788                 }
 789                 tunnelsend(b, l + (q - b), t); // send it
 790         }
 791 }
 792
 793 // send a CHAP PP packet
 794 void sendchap(tunnelidt t, sessionidt s)
 795 {
 796         u8 b[MAXCONTROL];
 797         u16 r = session[s].radius;
 798         u8 *q;
 799
 800         CSTAT(call_sendchap);
 801
 802         if (!r)
 803         {
 804                 log(1, 0, s, t, "No RADIUS to send challenge\n");
 805                 STAT(tunnel_tx_errors);
 806                 return ;
 807         }
 808         log(1, 0, s, t, "Send CHAP challenge\n");
 809         {
 810                 // new challenge
 811                 int n;
 812                 for (n = 0; n < 15; n++)
 813                         radius[r].auth[n] = rand();
 814         }
 815         radius[r].chap = 1;             // CHAP not PAP
 816         radius[r].id++;
 817         if (radius[r].state != RADIUSCHAP)
 818                 radius[r].try = 0;
 819         radius[r].state = RADIUSCHAP;
 820         radius[r].retry = backoff(radius[r].try++);
 821         if (radius[r].try > 5)
 822         {
 823                 sessionshutdown(s, "Timeout CHAP");
 824                 STAT(tunnel_tx_errors);
 825                 return ;
 826         }
 827         q = makeppp(b, sizeof(b), 0, 0, t, s, PPPCHAP);
 828         if (!q) {
 829                 log(1, 0, s, t, "failed to send CHAP challenge.\n");
 830                 return;
 831         }
 832         *q = 1;                                 // challenge
 833         q[1] = radius[r].id;                    // ID
 834         q[4] = 16;                              // length
 835         memcpy(q + 5, radius[r].auth, 16);      // challenge
 836         strcpy(q + 21, hostname);               // our name
 837         *(u16 *) (q + 2) = htons(strlen(hostname) + 21); // length
 838         tunnelsend(b, strlen(hostname) + 21 + (q - b), t); // send it
 839 }
 840
 841 // fill in a L2TP message with a PPP frame,
 842 // copies existing PPP message and changes magic number if seen
 843 // returns start of PPP frame
 844 u8 *makeppp(u8 *b, int size, u8 *p, int l, tunnelidt t, sessionidt s, u16 mtype)
 845 {
 846         if (size < 12)
 847                 return NULL;    // Need more space than this!!
 848
 849         *(u16 *) (b + 0) = htons(0x0002); // L2TP with no options
 850         *(u16 *) (b + 2) = htons(tunnel[t].far); // tunnel
 851         *(u16 *) (b + 4) = htons(session[s].far); // session
 852         b += 6;
 853         if (mtype == PPPLCP || !(session[s].l2tp_flags & SESSIONACFC))
 854         {
 855                 *(u16 *) b = htons(0xFF03); // HDLC header
 856                 b += 2;
 857         }
 858         if (mtype < 0x100 && session[s].l2tp_flags & SESSIONPFC)
 859                 *b++ = mtype;
 860         else
 861         {
 862                 *(u16 *) b = htons(mtype);
 863                 b += 2;
 864         }
 865
 866         if (l + 12 > size) {
 867                 log(3,0,0,0, "Would have overflowed the buffer in makeppp: size %d, len %d.\n", size, l);
 868                 return NULL;    // Run out of room to hold the packet!
 869         }
 870         if (p && l)
 871                 memcpy(b, p, l);
 872         return b;
 873 }
 874
 875 // find a PPP option, returns point to option, or 0 if not found
 876 u8 *findppp(u8 *b, u8 mtype)
 877 {
 878         u16 l = ntohs(*(u16 *) (b + 2));
 879         if (l < 4)
 880                 return 0;
 881         b += 4;
 882         l -= 4;
 883         while (l)
 884         {
 885                 if (l < b[1] || !b[1])
 886                         return 0;               // faulty
 887                 if (*b == mtype)
 888                         return b;
 889                 l -= b[1];
 890                 b += b[1];
 891         }
 892         return 0;
 893 }
 894
 895 // Send initial LCP ConfigReq
 896 void initlcp(tunnelidt t, sessionidt s)
 897 {
 898         char b[500] = {0}, *q;
 899
 900         q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPLCP);
 901         if (!q) {
 902                 log(1, 0, s, t, "Failed to send LCP ConfigReq.\n");
 903                 return;
 904         }
 905         log(4, 0, s, t, "Sending LCP ConfigReq for PAP\n");
 906         *q = ConfigReq;
 907         *(u8 *)(q + 1) = (time_now % 255) + 1; // ID
 908         *(u16 *)(q + 2) = htons(14); // Length
 909         *(u8 *)(q + 4) = 5;
 910         *(u8 *)(q + 5) = 6;
 911         *(u32 *)(q + 6) = htonl(session[s].magic);
 912         *(u8 *)(q + 10) = 3;
 913         *(u8 *)(q + 11) = 4;
 914         *(u16 *)(q + 12) = htons(0xC023); // PAP
 915         tunnelsend(b, 12 + 14, t);
 916 }
 917
 918 // Send CCP reply
 919 void sendccp(tunnelidt t, sessionidt s)
 920 {
 921         char *q, b[500] = {0};
 922
 923         q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPCCP);
 924         *q = ConfigReq;
 925         *(u8 *)(q + 1) = (time_now % 255) + 1; // ID
 926         *(u16 *)(q + 2) = htons(4); // Length
 927         log_hex(5, "PPPCCP", q, 4);
 928         tunnelsend(b, (q - b) + 4 , t);
 929 }
 930