| 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 -------------------------------------------------*/ |