ppp.c

   1 // L2TPNS PPP Stuff
   2
   3 char const *cvs_id_ppp = "$Id: ppp.c,v 1.15 2004-09-19 23:19:23 fred_nerk 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
  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         if (*p != 1)
  45         {
  46                 log(1, 0, s, t, "Unexpected PAP code %d\n", *p);
  47                 STAT(tunnel_rx_errors);
  48                 return ;
  49         }
  50         if (ntohs(*(u16 *) (p + 2)) > l)
  51         {
  52                 log(1, 0, s, t, "Length mismatch PAP %d/%d\n", ntohs(*(u16 *) (p + 2)), l);
  53                 STAT(tunnel_rx_errors);
  54                 return ;
  55         }
  56         {
  57                 u8 *b = p;
  58                 b += 4;
  59                 if (*b && *b < sizeof(user))
  60                         memcpy(user, b + 1, *b);
  61                 user[*b] = 0;
  62                 b += 1 + *b;
  63                 if (*b && *b < sizeof(pass))
  64                         memcpy(pass, b + 1, *b);
  65                 pass[*b] = 0;
  66                 log(3, 0, s, t, "PAP login %s/%s\n", user, pass);
  67         }
  68         if (session[s].ip || !session[s].radius)
  69         {
  70                 // respond now, either no RADIUS available or already authenticated
  71                 u8 b[MAXCONTROL];
  72                 u8 id = p[1];
  73                 u8 *p = makeppp(b, sizeof(b), 0, 0, t, s, PPPPAP);
  74                 if (!p) {       // Failed to make ppp header!
  75                         log(1,0,0,0, "Failed to make PPP header in process pap!\n");
  76                         return;
  77                 }
  78                 if (session[s].ip)
  79                         *p = 2;                 // ACK
  80                 else
  81                         *p = 3;                 // cant authorise
  82                 p[1] = id;
  83                 *(u16 *) (p + 2) = htons(5);    // length
  84                 p[4] = 0;                       // no message
  85                 if (session[s].ip)
  86                 {
  87                         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);
  88                         session[s].flags &= ~SF_IPCP_ACKED;
  89                 }
  90                 else
  91                 {
  92                         log(1, 0, s, t, "No radius session available to authenticate session...\n");
  93                 }
  94                 log(3, 0, s, t, "Fallback response to PAP (%s)\n", (session[s].ip) ? "ACK" : "NAK");
  95                 tunnelsend(b, 5 + (p - b), t); // send it
  96         }
  97         else
  98         {
  99                 // set up RADIUS request
 100                 u16 r = session[s].radius;
 101
 102                 // Run PRE_AUTH plugins
 103                 struct param_pre_auth packet = { &tunnel[t], &session[s], strdup(user), strdup(pass), PPPPAP, 1 };
 104                 run_plugins(PLUGIN_PRE_AUTH, &packet);
 105                 if (!packet.continue_auth)
 106                 {
 107                         log(3, 0, s, t, "A plugin rejected PRE_AUTH\n");
 108                         if (packet.username) free(packet.username);
 109                         if (packet.password) free(packet.password);
 110                         return;
 111                 }
 112
 113                 strncpy(session[s].user, packet.username, sizeof(session[s].user) - 1);
 114                 strncpy(radius[r].pass, packet.password, sizeof(radius[r].pass) - 1);
 115
 116                 free(packet.username);
 117                 free(packet.password);
 118
 119                 radius[r].id = p[1];
 120                 log(3, 0, s, t, "Sending login for %s/%s to radius\n", user, pass);
 121                 radiussend(r, RADIUSAUTH);
 122         }
 123 }
 124
 125 // Process CHAP messages
 126 void processchap(tunnelidt t, sessionidt s, u8 * p, u16 l)
 127 {
 128         u16 r;
 129         u16 len;
 130
 131
 132         CSTAT(call_processchap);
 133
 134         log_hex(5, "CHAP", p, l);
 135         r = session[s].radius;
 136         if (!r)
 137         {
 138                 log(1, 0, s, t, "Unexpected CHAP message\n");
 139
 140 // FIXME: Need to drop the session here.
 141
 142                 STAT(tunnel_rx_errors);
 143                 return;
 144         }
 145         if (*p != 2)
 146         {
 147                 log(1, 0, s, t, "Unexpected CHAP response code %d\n", *p);
 148                 STAT(tunnel_rx_errors);
 149                 return;
 150         }
 151         if (p[1] != radius[r].id)
 152         {
 153                 log(1, 0, s, t, "Wrong CHAP response ID %d (should be %d) (%d)\n", p[1], radius[r].id, r);
 154                 STAT(tunnel_rx_errors);
 155                 return ;
 156         }
 157         len = ntohs(*(u16 *) (p + 2));
 158         if (len > l)
 159         {
 160                 log(1, 0, s, t, "Bad CHAP length %d\n", len);
 161                 STAT(tunnel_rx_errors);
 162                 return ;
 163         }
 164         if (p[4] != 16)
 165         {
 166                 log(1, 0, s, t, "Bad CHAP response length %d\n", p[4]);
 167                 STAT(tunnel_rx_errors);
 168                 return ;
 169         }
 170         if (len - 21 >= sizeof(session[s].user))
 171         {
 172                 log(1, 0, s, t, "CHAP user too long %d\n", len - 21);
 173                 STAT(tunnel_rx_errors);
 174                 return ;
 175         }
 176
 177         // Run PRE_AUTH plugins
 178         {
 179                 struct param_pre_auth packet = { &tunnel[t], &session[s], NULL, NULL, PPPCHAP, 1 };
 180
 181                 packet.username = calloc(len-20, 1);
 182                 packet.password = calloc(16, 1);
 183                 memcpy(packet.username, p + 21, len - 21);
 184                 memcpy(packet.password, p + 5, 16);
 185
 186                 run_plugins(PLUGIN_PRE_AUTH, &packet);
 187                 if (!packet.continue_auth)
 188                 {
 189                         log(3, 0, s, t, "A plugin rejected PRE_AUTH\n");
 190                         if (packet.username) free(packet.username);
 191                         if (packet.password) free(packet.password);
 192                         return;
 193                 }
 194
 195                 strncpy(session[s].user, packet.username, sizeof(session[s].user) - 1);
 196                 memcpy(radius[r].pass, packet.password, 16);
 197
 198                 free(packet.username);
 199                 free(packet.password);
 200         }
 201
 202         radius[r].chap = 1;
 203         log(3, 0, s, t, "CHAP login %s\n", session[s].user);
 204         radiussend(r, RADIUSAUTH);
 205 }
 206
 207 char *ppp_lcp_types[] = {
 208         NULL,
 209         "ConfigReq",
 210         "ConfigAck",
 211         "ConfigNak",
 212         "ConfigRej",
 213         "TerminateReq",
 214         "TerminateAck",
 215         "CodeRej",
 216         "ProtocolRej",
 217         "EchoReq",
 218         "EchoReply",
 219         "DiscardRequest",
 220         "IdentRequest",
 221 };
 222
 223 void dumplcp(u8 *p, int l)
 224 {
 225         signed int x = l - 4;
 226         u8 *o = (p + 4);
 227
 228         log_hex(5, "PPP LCP Packet", p, l);
 229         log(4, 0, 0, 0, "PPP LCP Packet type %d (%s len %d)\n", *p, ppp_lcp_types[(int)*p], ntohs( ((u16 *) p)[1]) );
 230         log(4, 0, 0, 0, "Length: %d\n", l);
 231         if (*p != ConfigReq && *p != ConfigRej && *p != ConfigAck)
 232                 return;
 233
 234         while (x > 2)
 235         {
 236                 int type = o[0];
 237                 int length = o[1];
 238                 if (length < 2)
 239                 {
 240                         log(4, 0, 0, 0, "       Option length is %d...\n", length);
 241                         break;
 242                 }
 243                 if (type == 0)
 244                 {
 245                         log(4, 0, 0, 0, "       Option type is 0...\n");
 246                         x -= length;
 247                         o += length;
 248                         continue;
 249                 }
 250                 switch (type)
 251                 {
 252                         case 1: // Maximum-Receive-Unit
 253                                 if (length == 4)
 254                                         log(4, 0, 0, 0, "    %s %d\n", lcp_types[type], ntohs(*(u16 *)(o + 2)));
 255                                 else
 256                                         log(4, 0, 0, 0, "    %s odd length %d\n", lcp_types[type], length);
 257                                 break;
 258                         case 3: // Authentication-Protocol
 259                                 {
 260                                         if (length == 4)
 261                                         {
 262                                                 int proto = ntohs(*(u16 *)(o + 2));
 263                                                 log(4, 0, 0, 0, "   %s 0x%x (%s)\n", lcp_types[type], proto,
 264                                                         proto == 0xC223 ? "CHAP" :
 265                                                         proto == 0xC023 ? "PAP"  : "UNKNOWN");
 266                                         }
 267                                         else
 268                                                 log(4, 0, 0, 0, "   %s odd length %d\n", lcp_types[type], length);
 269                                         break;
 270                                 }
 271                         case 4: // Quality-Protocol
 272                                 {
 273                                         u32 qp = ntohl(*(u32 *)(o + 2));
 274                                         log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], qp);
 275                                         break;
 276                                 }
 277                         case 5: // Magic-Number
 278                                 {
 279                                         if (length == 6)
 280                                         {
 281                                                 u32 magicno = ntohl(*(u32 *)(o + 2));
 282                                                 log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], magicno);
 283                                         }
 284                                         else
 285                                                 log(4, 0, 0, 0, "   %s odd length %d\n", lcp_types[type], length);
 286                                         break;
 287                                 }
 288                         case 7: // Protocol-Field-Compression
 289                                 {
 290                                         log(4, 0, 0, 0, "    %s\n", lcp_types[type]);
 291                                         break;
 292                                 }
 293                         case 8: // Address-And-Control-Field-Compression
 294                                 {
 295                                         log(4, 0, 0, 0, "    %s\n", lcp_types[type]);
 296                                         break;
 297                                 }
 298                         default:
 299                                 log(2, 0, 0, 0, "    Unknown PPP LCP Option type %d\n", type);
 300                                 break;
 301                 }
 302                 x -= length;
 303                 o += length;
 304         }
 305 }
 306
 307 // Process LCP messages
 308 void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 309 {
 310         u8 b[MAXCONTROL];
 311         u8 *q = NULL;
 312         u32  magicno = 0;
 313
 314
 315         CSTAT(call_processlcp);
 316
 317         log_hex(5, "LCP", p, l);
 318         if (l < 4)
 319         {
 320                 log(1, session[s].ip, s, t, "Short LCP %d bytes\n", l);
 321                 STAT(tunnel_rx_errors);
 322                 return ;
 323         }
 324         if (*p == ConfigAck)
 325         {
 326                 log(3, session[s].ip, s, t, "LCP: Discarding ConfigAck\n");
 327                 session[s].flags |= SESSIONLCPACK;
 328         }
 329         else if (*p == ConfigReq)
 330         {
 331                 signed int x = l - 4;
 332                 u8 *o = (p + 4);
 333
 334                 log(3, session[s].ip, s, t, "LCP: ConfigReq (%d bytes)...\n", l);
 335                 dumplcp(p, l);
 336
 337                 while (x > 2)
 338                 {
 339                         int type = o[0];
 340                         int length = o[1];
 341                         if (length == 0 || type == 0) break;
 342                         switch (type)
 343                         {
 344                                 case 1: // Maximum-Receive-Unit
 345                                         session[s].mru = ntohs(*(u16 *)(o + 2));
 346                                         break;
 347                                 case 2: // asyncmap
 348                                         log_hex(2, "PPP LCP Packet", p, l);
 349                                         log(2, 0, 0, 0, "PPP LCP Packet type %d (%s len %d)\n", *p, ppp_lcp_types[(int)*p], ntohs( ((u16 *) p)[1]) );
 350                                         break;
 351                                 case 3: // Authentication-Protocol
 352                                         {
 353                                                 int proto = ntohs(*(u16 *)(o + 2));
 354                                                 if (proto == 0xC223)
 355                                                 {
 356                                                         log(2, session[s].ip, s, t, "    Remote end is trying to do CHAP. Rejecting it.\n");
 357
 358                                                         if (!q)
 359                                                         {
 360                                                                 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 361                                                                 if (!q) {
 362                                                                         log(2, session[s].ip, s, t, " Failed to send packet.\n");
 363                                                                         break;
 364                                                                 }
 365                                                                 *q++ = ConfigNak;
 366                                                         }
 367                                                         memcpy(q, o, length);
 368                                                         *(u16 *)(q += 2) = htons(0xC023); // NAK -> Use PAP instead
 369                                                         q += length;
 370                                                 }
 371                                                 break;
 372                                         }
 373                                 case 5: // Magic-Number
 374                                         {
 375                                                 magicno = ntohl(*(u32 *)(o + 2));
 376                                                 break;
 377                                         }
 378                                 case 4: // Quality-Protocol
 379                                 case 7: // Protocol-Field-Compression
 380                                 case 8: // Address-And-Control-Field-Compression
 381                                                 break;
 382                                 case 13: // CallBack option for LCP extention of win2000/routers L2TP client
 383                                 case 17:
 384                                 case 18:
 385                                 {
 386                                         // Reject LCP CallBack
 387                                         log(2, session[s].ip, s, t, "    PPP LCP Option type %d, len=%d\n", type, length);
 388                                         memcpy(p + 4, o, length);
 389                                         *(u16 *)(p + 2) = htons(length + 4);
 390                                         *p = ConfigRej;
 391                                         q = makeppp(b,sizeof(b), p, length + 4, t, s, PPPLCP);
 392                                         tunnelsend(b, 12 + length + 4, t);
 393                                         return;
 394                                         }
 395
 396                                 default:
 397                                         // Reject Unknown LCP Option to stop to send it again
 398                                         log(2, session[s].ip, s, t, "    Unknown PPP LCP Option type %d\n", type);
 399                                         memcpy(p + 4, o, length);
 400                                         *(u16 *)(p + 2) = htons(length + 4);
 401                                         *p = ConfigRej;
 402                                         q = makeppp(b,sizeof(b), p, length + 4, t, s, PPPLCP);
 403                                         tunnelsend(b, 12 + length + 4, t);
 404                                         return;
 405                         }
 406                         x -= length;
 407                         o += length;
 408                 }
 409
 410                 if (!q)
 411                 {
 412                         // Send back a ConfigAck
 413                         log(3, session[s].ip, s, t, "ConfigReq accepted, sending as Ack\n");
 414                         // for  win2k L2TP clientis  and LCP renegotiation of alive session
 415                         if (magicno || l == 4) initlcp(t, s);
 416                         q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 417                         if (!q)
 418                         {
 419                                 log(3, session[s].ip, s, t, " failed to create packet.\n");
 420                                 return;
 421                         }
 422                         *q = ConfigAck;
 423                         tunnelsend(b, l + (q - b), t);
 424                 }
 425                 else
 426                 {
 427                         // Already built a ConfigNak... send it
 428                         log(3, session[s].ip, s, t, "Sending ConfigNak\n");
 429                         tunnelsend(b, l + (q - b), t);
 430                 }
 431
 432                 if (!(session[s].flags & SESSIONLCPACK))
 433                         initlcp(t, s);
 434         }
 435         else if (*p == ConfigNak)
 436         {
 437                 log(1, session[s].ip, s, t, "Remote end sent a ConfigNak. Ignoring\n");
 438                 dumplcp(p, l);
 439                 return ;
 440         }
 441         else if (*p == TerminateReq)
 442         {
 443                 *p = TerminateAck;      // close
 444                 q = makeppp(b, sizeof(b),  p, l, t, s, PPPLCP);
 445                 if (!q) {
 446                         log(3, session[s].ip, s, t, "Failed to create PPP packet in processlcp.\n");
 447                         return;
 448                 }
 449                 log(3, session[s].ip, s, t, "LCP: Received TerminateReq. Sending TerminateAck\n");
 450                 sessionshutdown(s, "Remote end closed connection.");
 451                 tunnelsend(b, l + (q - b), t); // send it
 452         }
 453         else if (*p == TerminateAck)
 454         {
 455                 sessionshutdown(s, "Connection closed.");
 456         }
 457         else if (*p == EchoReq)
 458         {
 459                 *p = EchoReply;         // reply
 460                 *(u32 *) (p + 4) = htonl(session[s].magic); // our magic number
 461                 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 462                 if (!q) {
 463                         log(3, session[s].ip, s, t, " failed to send EchoReply.\n");
 464                         return;
 465                 }
 466                 log(5, session[s].ip, s, t, "LCP: Received EchoReq. Sending EchoReply\n");
 467                 tunnelsend(b, l + (q - b), t); // send it
 468         }
 469         else if (*p == EchoReply)
 470         {
 471                 // Ignore it, last_packet time is set earlier than this.
 472         }
 473         else if (*p == IdentRequest)
 474         {
 475                 *p = CodeRej;
 476                 if (l > MAXCONTROL)
 477                 {
 478                         log(1, 0, s, t, "Truncated Ident Packet (length=%d) to 1400 bytes\n", l);
 479                         l = 1400;
 480                 }
 481                 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
 482                 if (!q)
 483                 {
 484                         log(3, session[s].ip, s, t, "Failed to create IdentRej.\n");
 485                         return;
 486                 }
 487                 log_hex(5, "LCPIdentRej", q, l + 4);
 488                 tunnelsend(b, 12 + 4 + l, t);
 489         }
 490         else
 491         {
 492                 log(1, session[s].ip, s, t, "Unexpected LCP code %d\n", *p);
 493                 STAT(tunnel_rx_errors);
 494                 return ;
 495         }
 496 }
 497
 498 // Process IPCP messages
 499 void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 500 {
 501
 502         CSTAT(call_processipcp);
 503
 504         log_hex(5, "IPCP", p, l);
 505         if (l < 5)
 506         {
 507                 log(1, 0, s, t, "Short IPCP %d bytes\n", l);
 508                 STAT(tunnel_rx_errors);
 509                 return ;
 510         }
 511         if (*p == ConfigAck)
 512         {
 513                 // happy with our IPCP
 514                 u16 r = session[s].radius;
 515                 if ((!r || radius[r].state == RADIUSIPCP) && !session[s].walled_garden)
 516                 {
 517                         if (!r)
 518                                 r = radiusnew(s);
 519                         if (r)
 520                                 radiussend(r, RADIUSSTART); // send radius start, having got IPCP at last
 521                 }
 522                 session[s].flags |= SF_IPCP_ACKED;
 523
 524                 log(3, session[s].ip, s, t, "IPCP Acked, session is now active\n");
 525                 return;
 526         }
 527         if (*p != ConfigReq)
 528         {
 529                 log(1, 0, s, t, "Unexpected IPCP code %d\n", *p);
 530                 STAT(tunnel_rx_errors);
 531                 return ;
 532         }
 533         log(4, session[s].ip, s, t, "IPCP ConfigReq received\n");
 534         if (ntohs(*(u16 *) (p + 2)) > l)
 535         {
 536                 log(1, 0, s, t, "Length mismatch IPCP %d/%d\n", ntohs(*(u16 *) (p + 2)), l);
 537                 STAT(tunnel_rx_errors);
 538                 return ;
 539         }
 540         if (!session[s].ip)
 541         {
 542                 log(3, 0, s, t, "Waiting on radius reply\n");
 543                 return;                 // have to wait on RADIUS reply
 544         }
 545         // form a config reply quoting the IP in the session
 546         {
 547                 u8 b[MAXCONTROL];
 548                 u8 *i,
 549                 *q;
 550
 551                 l = ntohs(*(u16 *) (p + 2)); // We must use length from IPCP len field
 552                 q = p + 4;
 553                 i = p + l;
 554                 while (q < i && q[1])
 555                 {
 556                         if (*q != 0x81 && *q != 0x83 && *q != 3)
 557                                 break;
 558                         q += q[1];
 559                 }
 560                 if (q < i)
 561                 {
 562                         // reject
 563                         u16 n = 4;
 564                         i = p + l;
 565                         if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP)))
 566                         {
 567                                 log(2, 0, s, t, "Failed to send IPCP ConfigRej\n");
 568                                 return;
 569                         }
 570                         *q = ConfigRej;
 571                         p += 4;
 572                         while (p < i && p[1])
 573                         {
 574                                 if (*p != 0x81 && *p != 0x83 && *p != 3)
 575                                 {
 576                                         log(2, 0, s, t, "IPCP reject %d\n", *p);
 577                                         memcpy(q + n, p, p[1]);
 578                                         n += p[1];
 579                                 }
 580                                 p += p[1];
 581                         }
 582                         *(u16 *) (q + 2) = htons(n);
 583                         log(4, session[s].ip, s, t, "Sending ConfigRej\n");
 584                         tunnelsend(b, n + (q - b), t); // send it
 585                 }
 586                 else
 587                 {
 588                         log(4, session[s].ip, s, t, "Sending ConfigAck\n");
 589                         *p = ConfigAck;
 590                         if ((i = findppp(p, 0x81))) // Primary DNS address
 591                         {
 592                                 if (*(u32 *) (i + 2) != htonl(session[s].dns1))
 593                                 {
 594                                         *(u32 *) (i + 2) = htonl(session[s].dns1);
 595                                         *p = ConfigNak;
 596                                         log(5, session[s].ip, s, t, "   DNS1 = %s\n", inet_toa(session[s].dns1));
 597                                 }
 598                         }
 599                         if ((i = findppp(p, 0x83))) // Secondary DNS address (TBA, is it)
 600                         {
 601                                 if (*(u32 *) (i + 2) != htonl(session[s].dns2))
 602                                 {
 603                                         *(u32 *) (i + 2) = htonl(session[s].dns2);
 604                                         *p = ConfigNak;
 605                                         log(5, session[s].ip, s, t, "   DNS2 = %s\n", inet_toa(session[s].dns1));
 606                                 }
 607                         }
 608                         i = findppp(p, 3);              // IP address
 609                         if (!i || i[1] != 6)
 610                         {
 611                                 log(1, 0, s, t, "No IP in IPCP request\n");
 612                                 STAT(tunnel_rx_errors);
 613                                 return ;
 614                         }
 615                         if (*(u32 *) (i + 2) != htonl(session[s].ip))
 616                         {
 617                                 *(u32 *) (i + 2) = htonl(session[s].ip);
 618                                 *p = ConfigNak;
 619                                 log(4, session[s].ip, s, t, " No, a ConfigNak, client is requesting IP - sending %s\n",
 620                                                 inet_toa(htonl(session[s].ip)));
 621                         }
 622                         if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP)))
 623                         {
 624                                 log(2, 0, s, t, " Failed to send IPCP packet.\n");
 625                                 return;
 626                         }
 627                         tunnelsend(b, l + (q - b), t); // send it
 628                 }
 629         }
 630 }
 631
 632 // process IP packet received
 633 //
 634 // This MUST be called with at least 4 byte behind 'p'.
 635 // (i.e. this routine writes to p[-4]).
 636 void processipin(tunnelidt t, sessionidt s, u8 * p, u16 l)
 637 {
 638         ipt ip;
 639
 640         CSTAT(call_processipin);
 641
 642         log_hex(5, "IP", p, l);
 643
 644         ip = ntohl(*(u32 *)(p + 12));
 645
 646         if (l > MAXETHER)
 647         {
 648                 log(1, ip, s, t, "IP packet too long %d\n", l);
 649                 STAT(tunnel_rx_errors);
 650                 return ;
 651         }
 652
 653         // no spoof (do sessionbyip to handled statically routed subnets)
 654         if (ip != session[s].ip && sessionbyip(htonl(ip)) != s)
 655         {
 656                 log(5, ip, s, t, "Dropping packet with spoofed IP %s\n", inet_toa(htonl(ip)));
 657                 return;
 658         }
 659
 660         // Add on the tun header
 661         p -= 4;
 662         *(u32 *)p = htonl(0x00000800);
 663         l += 4;
 664
 665         if (session[s].tbf_in && !config->cluster_iam_master) { // Are we throttled and a slave?
 666                 master_throttle_packet(session[s].tbf_in, p, l); // Pass it to the master for handling.
 667                 return;
 668         }
 669
 670         session[s].cin += l - 4;
 671         session[s].total_cin += l - 4;
 672         sess_count[s].cin += l - 4;
 673
 674         session[s].pin++;
 675         eth_tx += l - 4;
 676
 677         if (session[s].snoop_ip && session[s].snoop_port)
 678         {
 679                 // Snooping this session
 680                 snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
 681         }
 682         STAT(tun_tx_packets);
 683         INC_STAT(tun_tx_bytes, l);
 684
 685         if (session[s].tbf_in && config->cluster_iam_master) { // Are we throttled and a master?? actually handle the throttled packets.
 686                 tbf_queue_packet(session[s].tbf_in, p, l);
 687                 return;
 688         }
 689
 690         // send to ethernet
 691         if (tun_write(p, l) < 0)
 692         {
 693                 STAT(tun_tx_errors);
 694                 log(0, 0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
 695                         l, strerror(errno), tunfd, p);
 696         }
 697
 698 }
 699
 700 //
 701 // Helper routine for the TBF filters.
 702 // Used to send queued data in from the user.
 703 //
 704 void send_ipin(sessionidt s, u8 *buf, int len)
 705 {
 706         log_hex(5, "IP in throttled", buf, len);
 707         if (write(tunfd, buf, len) < 0)
 708         {
 709                 STAT(tun_tx_errors);
 710                 log(0, 0, 0, 0, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
 711                         len, strerror(errno), tunfd, buf);
 712         }
 713
 714         // Increment packet counters
 715         session[s].cin += len - 4;
 716         session[s].total_cin += len - 4;
 717         sess_count[s].cin += len - 4;
 718
 719         session[s].pin++;
 720         eth_tx += len - 4;
 721 }
 722
 723
 724 // Process LCP messages
 725 void processccp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 726 {
 727
 728         CSTAT(call_processccp);
 729
 730         log_hex(5, "CCP", p, l);
 731         if (l < 2 || (*p != ConfigReq && *p != TerminateReq))
 732         {
 733                 log(1, 0, s, t, "Unexpecetd CCP request code %d\n", *p);
 734                 STAT(tunnel_rx_errors);
 735                 return ;
 736         }
 737         // reject
 738         {
 739                 u8 b[MAXCONTROL];
 740                 u8 *q;
 741                 if (*p == ConfigReq)
 742                 {
 743                         if (l < 6)
 744                         {
 745                                 *p = ConfigAck;         // accept no compression
 746                         }
 747                         else
 748                         {
 749                                 *p = ConfigRej;         // reject
 750                                 sendccp(t, s);
 751                         }
 752                 }
 753                 else
 754                         *p = TerminateAck;              // close
 755                 if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPCCP)))
 756                 {
 757                         log(1,0,0,0, "Failed to send CCP packet.\n");
 758                         return;
 759                 }
 760                 tunnelsend(b, l + (q - b), t); // send it
 761         }
 762 }
 763
 764 // send a CHAP PP packet
 765 void sendchap(tunnelidt t, sessionidt s)
 766 {
 767         u8 b[MAXCONTROL];
 768         u16 r = session[s].radius;
 769         u8 *q;
 770
 771         CSTAT(call_sendchap);
 772
 773         if (!r)
 774         {
 775                 log(1, 0, s, t, "No RADIUS to send challenge\n");
 776                 STAT(tunnel_tx_errors);
 777                 return ;
 778         }
 779         log(1, 0, s, t, "Send CHAP challenge\n");
 780         {
 781                 // new challenge
 782                 int n;
 783                 for (n = 0; n < 15; n++)
 784                         radius[r].auth[n] = rand();
 785         }
 786         radius[r].chap = 1;             // CHAP not PAP
 787         radius[r].id++;
 788         if (radius[r].state != RADIUSCHAP)
 789                 radius[r].try = 0;
 790         radius[r].state = RADIUSCHAP;
 791         radius[r].retry = backoff(radius[r].try++);
 792         if (radius[r].try > 5)
 793         {
 794                 sessionshutdown(s, "Timeout CHAP");
 795                 STAT(tunnel_tx_errors);
 796                 return ;
 797         }
 798         q = makeppp(b, sizeof(b), 0, 0, t, s, PPPCHAP);
 799         if (!q) {
 800                 log(1, 0, s, t, "failed to send CHAP challenge.\n");
 801                 return;
 802         }
 803         *q = 1;                                 // challenge
 804         q[1] = radius[r].id;                    // ID
 805         q[4] = 16;                              // length
 806         memcpy(q + 5, radius[r].auth, 16);      // challenge
 807         strcpy(q + 21, hostname);               // our name
 808         *(u16 *) (q + 2) = htons(strlen(hostname) + 21); // length
 809         tunnelsend(b, strlen(hostname) + 21 + (q - b), t); // send it
 810 }
 811
 812 // fill in a L2TP message with a PPP frame,
 813 // copies existing PPP message and changes magic number if seen
 814 // returns start of PPP frame
 815 u8 *makeppp(u8 * b, int size, u8 * p, int l, tunnelidt t, sessionidt s, u16 mtype)
 816 {
 817         if (size < 12)
 818                 return NULL;    // Need more space than this!!
 819
 820         *(u16 *) (b + 0) = htons(0x0002); // L2TP with no options
 821         *(u16 *) (b + 2) = htons(tunnel[t].far); // tunnel
 822         *(u16 *) (b + 4) = htons(session[s].far); // session
 823         b += 6;
 824         if (mtype && !(session[s].l2tp_flags & SESSIONACFC))
 825         {
 826                 *(u16 *) b = htons(0xFF03); // HDLC header
 827                 b += 2;
 828         }
 829         if (mtype < 0x100 && session[s].l2tp_flags & SESSIONPFC)
 830                 *b++ = mtype;
 831         else
 832         {
 833                 *(u16 *) b = htons(mtype);
 834                 b += 2;
 835         }
 836
 837         if (l + 12 > size) {
 838                 log(3,0,0,0, "Would have overflowed the buffer in makeppp: size %d, len %d.\n", size, l);
 839                 return NULL;    // Run out of room to hold the packet!
 840         }
 841         if (p && l)
 842                 memcpy(b, p, l);
 843         return b;
 844 }
 845
 846 // find a PPP option, returns point to option, or 0 if not found
 847 u8 *findppp(u8 * b, u8 mtype)
 848 {
 849         u16 l = ntohs(*(u16 *) (b + 2));
 850         if (l < 4)
 851                 return 0;
 852         b += 4;
 853         l -= 4;
 854         while (l)
 855         {
 856                 if (l < b[1] || !b[1])
 857                         return 0;               // faulty
 858                 if (*b == mtype)
 859                         return b;
 860                 l -= b[1];
 861                 b += b[1];
 862         }
 863         return 0;
 864 }
 865
 866 // Send initial LCP ConfigReq
 867 void initlcp(tunnelidt t, sessionidt s)
 868 {
 869         char b[500] = {0}, *q;
 870
 871         q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPLCP);
 872         if (!q) {
 873                 log(1, 0, s, t, "Failed to send LCP ConfigReq.\n");
 874                 return;
 875         }
 876         log(4, 0, s, t, "Sending LCP ConfigReq for PAP\n");
 877         *q = ConfigReq;
 878         *(u8 *)(q + 1) = (time_now % 255) + 1; // ID
 879         *(u16 *)(q + 2) = htons(14); // Length
 880         *(u8 *)(q + 4) = 5;
 881         *(u8 *)(q + 5) = 6;
 882         *(u32 *)(q + 6) = htonl(session[s].magic);
 883         *(u8 *)(q + 10) = 3;
 884         *(u8 *)(q + 11) = 4;
 885         *(u16 *)(q + 12) = htons(0xC023); // PAP
 886         tunnelsend(b, 12 + 14, t);
 887 }
 888
 889 // Send CCP reply
 890 void sendccp(tunnelidt t, sessionidt s)
 891 {
 892         char *q, b[500] = {0};
 893
 894         q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPCCP);
 895         *q = ConfigReq;
 896         *(u8 *)(q + 1) = (time_now % 255) + 1; // ID
 897         *(u16 *)(q + 2) = htons(4); // Length
 898         log_hex(5, "PPPCCP", q, 4);
 899         tunnelsend(b, (q - b) + 4 , t);
 900 }
 901