mdw@git.distorted.org.uk Git - tripe/blob - peer.c

   1 /* -*-c-*-
   2  *
   3  * $Id: peer.c,v 1.9 2003/07/13 11:19:49 mdw Exp $
   4  *
   5  * Communication with the peer
   6  *
   7  * (c) 2001 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Trivial IP Encryption (TrIPE).
  13  *
  14  * TrIPE is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * TrIPE is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with TrIPE; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: peer.c,v $
  32  * Revision 1.9  2003/07/13 11:19:49  mdw
  33  * Incopatible protocol fix!  Include message type code under MAC tag to prevent
  34  * cut-and-paste from key-exchange messages to general packet transport.
  35  *
  36  * Revision 1.8  2003/05/16 12:09:03  mdw
  37  * Allow binding to a chosen address.
  38  *
  39  * Revision 1.7  2003/04/15 14:12:05  mdw
  40  * Insert a newline to improve readability.
  41  *
  42  * Revision 1.6  2001/06/19 22:07:59  mdw
  43  * Use magic number for packet size.
  44  *
  45  * Revision 1.5  2001/03/03 11:15:19  mdw
  46  * Set the socket send and receive buffers to maximum.  At least this way,
  47  * we won't drop large packets on the floor.  If the administrator wants to
  48  * prevent fragmentation of TrIPE messages, he can lower the MTU on the
  49  * tunnel interface.  Getting path-MTU stuff out of the kernel is too much
  50  * system-specific hard work for this program.
  51  *
  52  * Revision 1.4  2001/02/16 21:40:24  mdw
  53  * Change key exchange message interface.  Maintain statistics.
  54  *
  55  * Revision 1.3  2001/02/04 17:10:58  mdw
  56  * Make file descriptors be nonblocking and close-on-exec.
  57  *
  58  * Revision 1.2  2001/02/03 22:40:29  mdw
  59  * Put timer information into the entropy pool when packets are received
  60  * and on similar events.  Reseed the generator on the interval timer.
  61  *
  62  * Revision 1.1  2001/02/03 20:26:37  mdw
  63  * Initial checkin.
  64  *
  65  */
  66
  67 /*----- Header files ------------------------------------------------------*/
  68
  69 #include "tripe.h"
  70
  71 /*----- Static variables --------------------------------------------------*/
  72
  73 static peer *peers = 0;
  74 static sel_file sock;
  75
  76 /*----- Main code ---------------------------------------------------------*/
  77
  78 /* --- @p_read@ --- *
  79  *
  80  * Arguments:   @int fd@ = file descriptor to read from
  81  *              @unsigned mode@ = what happened
  82  *              @void *v@ = an uninteresting pointer
  83  *
  84  * Returns:     ---
  85  *
  86  * Use:         Reads a packet from somewhere.
  87  */
  88
  89 static void p_read(int fd, unsigned mode, void *v)
  90 {
  91   peer *p;
  92   addr a;
  93   size_t sz;
  94   ssize_t n;
  95   int ch;
  96   buf b, bb;
  97
  98   /* --- Read the data --- */
  99
 100   TIMER;
 101   sz = sizeof(addr);
 102   n = recvfrom(fd, buf_i, sizeof(buf_i), 0, &a.sa, &sz);
 103   if (n < 0) {
 104     a_warn("error reading socket: %s", strerror(errno));
 105     return;
 106   }
 107
 108   /* --- Find the appropriate peer --- */
 109
 110   assert(a.sa.sa_family == AF_INET);
 111   for (p = peers; p; p = p->next) {
 112     if (p->peer.sin.sin_addr.s_addr == a.sin.sin_addr.s_addr &&
 113         p->peer.sin.sin_port == a.sin.sin_port)
 114       goto found;
 115   }
 116   a_warn("packet from unexpected peer: %s:%u",
 117        inet_ntoa(a.sin.sin_addr), (unsigned)ntohs(a.sin.sin_port));
 118   return;
 119
 120 found:
 121   T( trace(T_PEER, "peer: packet received from `%s'", p->name);
 122      trace_block(T_PACKET, "peer: packet contents", buf_i, n); )
 123
 124   /* --- Pick the packet apart --- */
 125
 126   p->st.t_last = time(0);
 127   p->st.n_in++;
 128   p->st.sz_in += n;
 129   buf_init(&b, buf_i, n);
 130   if ((ch = buf_getbyte(&b)) < 0) {
 131     a_warn("bad packet from `%s': no type byte", p->name);
 132     return;
 133   }
 134   switch (ch & MSG_CATMASK) {
 135     case MSG_PACKET:
 136       if (ch & MSG_TYPEMASK) {
 137         a_warn("unknown packet type from `%s'", p->name);
 138         p->st.n_reject++;
 139         return;
 140       }
 141       buf_init(&bb, buf_o, sizeof(buf_o));
 142       if (ksl_decrypt(&p->ks, MSG_PACKET, &b, &bb)) {
 143         p->st.n_reject++;
 144         a_warn("couldn't decrypt inbound packet from `%s'", p->name);
 145         return;
 146       }
 147       if (BOK(&bb)) {
 148         p->st.n_ipin++;
 149         p->st.sz_ipin += BSZ(&b);
 150         tun_inject(&p->t, &bb);
 151       } else {
 152         p->st.n_reject++;
 153         a_warn("packet build failed");
 154       }
 155       break;
 156     case MSG_KEYEXCH:
 157       kx_message(&p->kx, ch & MSG_TYPEMASK, &b);
 158       break;
 159     default:
 160       p->st.n_reject++;
 161       a_warn("bad packet from `%s': unknown packet type", p->name);
 162       break;
 163   }
 164 }
 165
 166 /* --- @p_txstart@ --- *
 167  *
 168  * Arguments:   @peer *p@ = pointer to peer block
 169  *              @unsigned msg@ = message type code
 170  *
 171  * Returns:     A pointer to a buffer to write to.
 172  *
 173  * Use:         Starts sending to a peer.  Only one send can happen at a
 174  *              time.
 175  */
 176
 177 buf *p_txstart(peer *p, unsigned msg)
 178 {
 179   buf_init(&p->b, buf_o, sizeof(buf_o));
 180   buf_putbyte(&p->b, msg);
 181   return (&p->b);
 182 }
 183
 184 /* --- @p_txend@ --- *
 185  *
 186  * Arguments:   @peer *p@ = pointer to peer block
 187  *
 188  * Returns:     ---
 189  *
 190  * Use:         Sends a packet to the peer.
 191  */
 192
 193 void p_txend(peer *p)
 194 {
 195   if (!BOK(&p->b)) {
 196     a_warn("packet build failed");
 197     return;
 198   }
 199   IF_TRACING(T_PEER, trace_block(T_PACKET, "peer: sending packet",
 200                                  BBASE(&p->b), BLEN(&p->b)); )
 201   if (sendto(sock.fd, BBASE(&p->b), BLEN(&p->b),
 202              0, &p->peer.sa, p->sasz) < 0)
 203     a_warn("packet send to `%s' failed: %s", p->name, strerror(errno));
 204   else {
 205     p->st.n_out++;
 206     p->st.sz_out += BLEN(&p->b);
 207   }
 208 }
 209
 210 /* --- @p_tun@ --- *
 211  *
 212  * Arguments:   @peer *p@ = pointer to peer block
 213  *              @buf *b@ = buffer containing incoming packet
 214  *
 215  * Returns:     ---
 216  *
 217  * Use:         Handles a packet which needs to be sent to a peer.
 218  */
 219
 220 void p_tun(peer *p, buf *b)
 221 {
 222   buf *bb = p_txstart(p, MSG_PACKET);
 223
 224   TIMER;
 225   if (ksl_encrypt(&p->ks, MSG_PACKET, b, bb))
 226     kx_start(&p->kx);
 227   if (BOK(bb) && BLEN(bb)) {
 228     p->st.n_ipout++;
 229     p->st.sz_ipout += BLEN(bb);
 230     p_txend(p);
 231   }
 232 }
 233
 234 /* --- @p_interval@ --- *
 235  *
 236  * Arguments:   ---
 237  *
 238  * Returns:     ---
 239  *
 240  * Use:         Called periodically to do tidying.
 241  */
 242
 243 void p_interval(void)
 244 {
 245   peer *p, *pp;
 246   int reload;
 247
 248   reload = km_interval();
 249   for (p = peers; p; p = pp) {
 250     pp = p->next;
 251     if (reload)
 252       kx_newkeys(&p->kx);
 253     ksl_prune(&p->ks);
 254   }
 255 }
 256
 257 /* --- @p_stats@ --- *
 258  *
 259  * Arguments:   @peer *p@ = pointer to a peer block
 260  *
 261  * Returns:     A pointer to the peer's statistics.
 262  */
 263
 264 stats *p_stats(peer *p) { return (&p->st); }
 265
 266 /* --- @p_ifname@ --- *
 267  *
 268  * Arguments:   @peer *p@ = pointer to a peer block
 269  *
 270  * Returns:     A pointer to the peer's interface name.
 271  */
 272
 273 const char *p_ifname(peer *p) { return (tun_ifname(&p->t)); }
 274
 275 /* --- @p_addr@ --- *
 276  *
 277  * Arguments:   @peer *p@ = pointer to a peer block
 278  *
 279  * Returns:     A pointer to the peer's address.
 280  */
 281
 282 const addr *p_addr(peer *p) { return (&p->peer); }
 283
 284 /* --- @p_init@ --- *
 285  *
 286  * Arguments:   @struct in_addr addr@ = address to bind to
 287  *              @unsigned port@ = port number to listen to
 288  *
 289  * Returns:     ---
 290  *
 291  * Use:         Initializes the peer system; creates the socket.
 292  */
 293
 294 void p_init(struct in_addr addr, unsigned port)
 295 {
 296   int fd;
 297   struct sockaddr_in sin;
 298   int len = PKBUFSZ;
 299
 300   /* --- Note on socket buffer sizes --- *
 301    *
 302    * For some bizarre reason, Linux 2.2 (at least) doubles the socket buffer
 303    * sizes I pass to @setsockopt@.  I'm not putting special-case code here
 304    * for Linux: BSD (at least TCPv2) does what I tell it rather than second-
 305    * guessing me.
 306    */
 307
 308   if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
 309     die(EXIT_FAILURE, "socket creation failed: %s", strerror(errno));
 310   BURN(sin);
 311   sin.sin_family = AF_INET;
 312   sin.sin_addr = addr;
 313   sin.sin_port = htons(port);
 314   if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)))
 315     die(EXIT_FAILURE, "bind failed: %s", strerror(errno));
 316   if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) ||
 317       setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len))) {
 318     die(EXIT_FAILURE, "failed to set socket buffer sizes: %s",
 319         strerror(errno));
 320   }
 321   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 322   sel_initfile(&sel, &sock, fd, SEL_READ, p_read, 0);
 323   sel_addfile(&sock);
 324   T( trace(T_PEER, "peer: created socket"); )
 325 }
 326
 327 /* --- @p_port@ --- *
 328  *
 329  * Arguments:   ---
 330  *
 331  * Returns:     Port number used for socket.
 332  */
 333
 334 unsigned p_port(void)
 335 {
 336   addr a;
 337   size_t sz = sizeof(addr);
 338
 339   if (getsockname(sock.fd, &a.sa, &sz))
 340     die(EXIT_FAILURE, "couldn't read port number: %s", strerror(errno));
 341   assert(a.sa.sa_family == AF_INET);
 342   return (ntohs(a.sin.sin_port));
 343 }
 344
 345 /* --- @p_create@ --- *
 346  *
 347  * Arguments:   @const char *name@ = name for this peer
 348  *              @struct sockaddr *sa@ = socket address of peer
 349  *              @size_t sz@ = size of socket address
 350  *
 351  * Returns:     Pointer to the peer block, or null if it failed.
 352  *
 353  * Use:         Creates a new named peer block.  No peer is actually attached
 354  *              by this point.
 355  */
 356
 357 peer *p_create(const char *name, struct sockaddr *sa, size_t sz)
 358 {
 359   peer *p = CREATE(peer);
 360   T( trace(T_PEER, "peer: creating new peer `%s'", name); )
 361   p->name = xstrdup(name);
 362   p->ks = 0;
 363   p->prev = 0;
 364   memcpy(&p->peer.sa, sa, sz);
 365   p->sasz = sz;
 366   memset(&p->st, 0, sizeof(stats));
 367   p->st.t_start = time(0);
 368   if (kx_init(&p->kx, p, &p->ks))
 369     goto tidy_0;
 370   if (tun_create(&p->t, p))
 371     goto tidy_1;
 372   p->next = peers;
 373   if (peers)
 374     peers->prev = p;
 375   peers = p;
 376   return (p);
 377
 378 tidy_1:
 379   kx_free(&p->kx);
 380 tidy_0:
 381   xfree(p->name);
 382   DESTROY(p);
 383   return (0);
 384 }
 385
 386 /* --- @p_name@ --- *
 387  *
 388  * Arguments:   @peer *p@ = pointer to a peer block
 389  *
 390  * Returns:     A pointer to the peer's name.
 391  */
 392
 393 const char *p_name(peer *p) { return (p->name); }
 394
 395 /* --- @p_find@ --- *
 396  *
 397  * Arguments:   @const char *name@ = name to look up
 398  *
 399  * Returns:     Pointer to the peer block, or null if not found.
 400  *
 401  * Use:         Finds a peer by name.
 402  */
 403
 404 peer *p_find(const char *name)
 405 {
 406   peer *p;
 407   for (p = peers; p; p = p->next) {
 408     if (strcmp(name, p->name) == 0)
 409       return (p);
 410   }
 411   return (0);
 412 }
 413
 414 /* --- @p_destroy@ --- *
 415  *
 416  * Arguments:   @peer *p@ = pointer to a peer
 417  *
 418  * Returns:     ---
 419  *
 420  * Use:         Destroys a peer.
 421  */
 422
 423 void p_destroy(peer *p)
 424 {
 425   T( trace(T_PEER, "peer: destroying peer `%s'", p->name); )
 426   ksl_free(&p->ks);
 427   kx_free(&p->kx);
 428   tun_destroy(&p->t);
 429   xfree(p->name);
 430   if (p->next)
 431     p->next->prev = p->prev;
 432   if (p->prev)
 433     p->prev->next = p->next;
 434   else
 435     peers = p->next;
 436   DESTROY(p);
 437 }
 438
 439 /* --- @p_first@, @p_next@ --- *
 440  *
 441  * Arguments:   @peer *p@ = a peer block
 442  *
 443  * Returns:     @peer_first@ returns the first peer in some ordering;
 444  *              @peer_next@ returns the peer following a given one in the
 445  *              same ordering.  Null is returned for the end of the list.
 446  */
 447
 448 peer *p_first(void) { return (peers); }
 449 peer *p_next(peer *p) { return (p->next); }
 450
 451 /*----- That's all, folks -------------------------------------------------*/