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

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