| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: peer.c,v 1.1 2001/02/03 20:26:37 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 1.1 2001/02/03 20:26:37 mdw |
| 33 | * Initial checkin. |
| 34 | * |
| 35 | */ |
| 36 | |
| 37 | /*----- Header files ------------------------------------------------------*/ |
| 38 | |
| 39 | #include "tripe.h" |
| 40 | |
| 41 | /*----- Static variables --------------------------------------------------*/ |
| 42 | |
| 43 | static peer *peers = 0; |
| 44 | static sel_file sock; |
| 45 | |
| 46 | /*----- Main code ---------------------------------------------------------*/ |
| 47 | |
| 48 | /* --- @p_read@ --- * |
| 49 | * |
| 50 | * Arguments: @int fd@ = file descriptor to read from |
| 51 | * @unsigned mode@ = what happened |
| 52 | * @void *v@ = an uninteresting pointer |
| 53 | * |
| 54 | * Returns: --- |
| 55 | * |
| 56 | * Use: Reads a packet from somewhere. |
| 57 | */ |
| 58 | |
| 59 | static void p_read(int fd, unsigned mode, void *v) |
| 60 | { |
| 61 | peer *p; |
| 62 | addr a; |
| 63 | size_t sz; |
| 64 | ssize_t n; |
| 65 | int ch; |
| 66 | buf b, bb; |
| 67 | |
| 68 | /* --- Read the data --- */ |
| 69 | |
| 70 | sz = sizeof(addr); |
| 71 | n = recvfrom(fd, buf_i, sizeof(buf_i), 0, &a.sa, &sz); |
| 72 | if (n < 0) { |
| 73 | a_warn("error reading socket: %s", strerror(errno)); |
| 74 | return; |
| 75 | } |
| 76 | |
| 77 | /* --- Find the appropriate peer --- */ |
| 78 | |
| 79 | assert(a.sa.sa_family == AF_INET); |
| 80 | T( trace(T_PEER, "packet from %s:%u", |
| 81 | inet_ntoa(a.sin.sin_addr), (unsigned)ntohs(a.sin.sin_port)); ) |
| 82 | for (p = peers; p; p = p->next) { |
| 83 | T( trace(T_PEER, "trying %s:%u", |
| 84 | inet_ntoa(p->peer.sin.sin_addr), (unsigned)ntohs(p->peer.sin.sin_port)); ) |
| 85 | if (p->peer.sin.sin_addr.s_addr == a.sin.sin_addr.s_addr && |
| 86 | p->peer.sin.sin_port == a.sin.sin_port) |
| 87 | goto found; |
| 88 | } |
| 89 | a_warn("packet from unexpected peer: %s:%u", |
| 90 | inet_ntoa(a.sin.sin_addr), (unsigned)ntohs(a.sin.sin_port)); |
| 91 | return; |
| 92 | |
| 93 | found: |
| 94 | T( trace(T_PEER, "peer: packet received from `%s'", p->name); |
| 95 | trace_block(T_PACKET, "peer: packet contents", buf_i, n); ) |
| 96 | |
| 97 | /* --- Pick the packet apart --- */ |
| 98 | |
| 99 | buf_init(&b, buf_i, n); |
| 100 | if ((ch = buf_getbyte(&b)) < 0) { |
| 101 | a_warn("bad packet from `%s': no type byte", p->name); |
| 102 | return; |
| 103 | } |
| 104 | switch (ch) { |
| 105 | case MSG_PACKET: |
| 106 | buf_init(&bb, buf_o, sizeof(buf_o)); |
| 107 | if (ks_decrypt(&p->ks, &b, &bb)) { |
| 108 | a_warn("couldn't decrypt inbound packet"); |
| 109 | return; |
| 110 | } |
| 111 | if (BOK(&bb)) |
| 112 | tun_inject(&p->t, &bb); |
| 113 | else |
| 114 | a_warn("packet build failed"); |
| 115 | break; |
| 116 | case MSG_PRECHALLENGE: |
| 117 | kx_prechallenge(&p->kx, &b); |
| 118 | break; |
| 119 | case MSG_CHALLENGE: |
| 120 | kx_challenge(&p->kx, &b); |
| 121 | break; |
| 122 | case MSG_RESPONSE: |
| 123 | kx_response(&p->kx, &b); |
| 124 | break; |
| 125 | default: |
| 126 | a_warn("bad packet from `%s': unknown packet type", p->name); |
| 127 | break; |
| 128 | } |
| 129 | } |
| 130 | |
| 131 | /* --- @p_txstart@ --- * |
| 132 | * |
| 133 | * Arguments: @peer *p@ = pointer to peer block |
| 134 | * @unsigned msg@ = message type code |
| 135 | * |
| 136 | * Returns: A pointer to a buffer to write to. |
| 137 | * |
| 138 | * Use: Starts sending to a peer. Only one send can happen at a |
| 139 | * time. |
| 140 | */ |
| 141 | |
| 142 | buf *p_txstart(peer *p, unsigned msg) |
| 143 | { |
| 144 | buf_init(&p->b, buf_o, sizeof(buf_o)); |
| 145 | buf_putbyte(&p->b, msg); |
| 146 | return (&p->b); |
| 147 | } |
| 148 | |
| 149 | /* --- @p_txend@ --- * |
| 150 | * |
| 151 | * Arguments: @peer *p@ = pointer to peer block |
| 152 | * |
| 153 | * Returns: --- |
| 154 | * |
| 155 | * Use: Sends a packet to the peer. |
| 156 | */ |
| 157 | |
| 158 | void p_txend(peer *p) |
| 159 | { |
| 160 | if (!BOK(&p->b)) { |
| 161 | a_warn("packet build failed"); |
| 162 | return; |
| 163 | } |
| 164 | IF_TRACING(T_PEER, trace_block(T_PACKET, "peer: sending packet", |
| 165 | BBASE(&p->b), BLEN(&p->b)); ) |
| 166 | if (sendto(sock.fd, BBASE(&p->b), BLEN(&p->b), |
| 167 | 0, &p->peer.sa, p->sasz) < 0) |
| 168 | a_warn("packet send to `%s' failed: %s", p->name, strerror(errno)); |
| 169 | } |
| 170 | |
| 171 | /* --- @p_tun@ --- * |
| 172 | * |
| 173 | * Arguments: @peer *p@ = pointer to peer block |
| 174 | * @buf *b@ = buffer containing incoming packet |
| 175 | * |
| 176 | * Returns: --- |
| 177 | * |
| 178 | * Use: Handles a packet which needs to be sent to a peer. |
| 179 | */ |
| 180 | |
| 181 | void p_tun(peer *p, buf *b) |
| 182 | { |
| 183 | buf *bb = p_txstart(p, MSG_PACKET); |
| 184 | if (ks_encrypt(&p->ks, b, bb)) |
| 185 | kx_start(&p->kx); |
| 186 | if (BCUR(bb) > BBASE(bb)) |
| 187 | p_txend(p); |
| 188 | } |
| 189 | |
| 190 | /* --- @p_interval@ --- * |
| 191 | * |
| 192 | * Arguments: --- |
| 193 | * |
| 194 | * Returns: --- |
| 195 | * |
| 196 | * Use: Called periodically to do tidying. |
| 197 | */ |
| 198 | |
| 199 | void p_interval(void) |
| 200 | { |
| 201 | peer *p, *pp; |
| 202 | int reload; |
| 203 | |
| 204 | reload = km_interval(); |
| 205 | for (p = peers; p; p = pp) { |
| 206 | pp = p->next; |
| 207 | if (reload) |
| 208 | kx_newkeys(&p->kx); |
| 209 | ks_prune(&p->ks); |
| 210 | } |
| 211 | } |
| 212 | |
| 213 | /* --- @p_ifname@ --- * |
| 214 | * |
| 215 | * Arguments: @peer *p@ = pointer to a peer block |
| 216 | * |
| 217 | * Returns: A pointer to the peer's interface name. |
| 218 | */ |
| 219 | |
| 220 | const char *p_ifname(peer *p) { return (tun_ifname(&p->t)); } |
| 221 | |
| 222 | /* --- @p_addr@ --- * |
| 223 | * |
| 224 | * Arguments: @peer *p@ = pointer to a peer block |
| 225 | * |
| 226 | * Returns: A pointer to the peer's address. |
| 227 | */ |
| 228 | |
| 229 | const addr *p_addr(peer *p) { return (&p->peer); } |
| 230 | |
| 231 | /* --- @p_init@ --- * |
| 232 | * |
| 233 | * Arguments: @unsigned port@ = port number to listen to |
| 234 | * |
| 235 | * Returns: --- |
| 236 | * |
| 237 | * Use: Initializes the peer system; creates the socket. |
| 238 | */ |
| 239 | |
| 240 | void p_init(unsigned port) |
| 241 | { |
| 242 | int fd; |
| 243 | struct sockaddr_in sin; |
| 244 | |
| 245 | if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) |
| 246 | die(EXIT_FAILURE, "socket creation failed: %s", strerror(errno)); |
| 247 | BURN(sin); |
| 248 | sin.sin_family = AF_INET; |
| 249 | sin.sin_addr.s_addr = INADDR_ANY; |
| 250 | sin.sin_port = htons(port); |
| 251 | if (bind(fd, (struct sockaddr *)&sin, sizeof(sin))) |
| 252 | die(EXIT_FAILURE, "bind failed: %s", strerror(errno)); |
| 253 | sel_initfile(&sel, &sock, fd, SEL_READ, p_read, 0); |
| 254 | sel_addfile(&sock); |
| 255 | T( trace(T_PEER, "peer: created socket"); ) |
| 256 | } |
| 257 | |
| 258 | /* --- @p_port@ --- * |
| 259 | * |
| 260 | * Arguments: --- |
| 261 | * |
| 262 | * Returns: Port number used for socket. |
| 263 | */ |
| 264 | |
| 265 | unsigned p_port(void) |
| 266 | { |
| 267 | addr a; |
| 268 | size_t sz = sizeof(addr); |
| 269 | |
| 270 | if (getsockname(sock.fd, &a.sa, &sz)) |
| 271 | die(EXIT_FAILURE, "couldn't read port number: %s", strerror(errno)); |
| 272 | assert(a.sa.sa_family == AF_INET); |
| 273 | return (ntohs(a.sin.sin_port)); |
| 274 | } |
| 275 | |
| 276 | /* --- @p_create@ --- * |
| 277 | * |
| 278 | * Arguments: @const char *name@ = name for this peer |
| 279 | * @struct sockaddr *sa@ = socket address of peer |
| 280 | * @size_t sz@ = size of socket address |
| 281 | * |
| 282 | * Returns: Pointer to the peer block, or null if it failed. |
| 283 | * |
| 284 | * Use: Creates a new named peer block. No peer is actually attached |
| 285 | * by this point. |
| 286 | */ |
| 287 | |
| 288 | peer *p_create(const char *name, struct sockaddr *sa, size_t sz) |
| 289 | { |
| 290 | peer *p = CREATE(peer); |
| 291 | T( trace(T_PEER, "peer: creating new peer `%s'", name); ) |
| 292 | p->name = xstrdup(name); |
| 293 | p->ks = 0; |
| 294 | p->prev = 0; |
| 295 | memcpy(&p->peer.sa, sa, sz); |
| 296 | p->sasz = sz; |
| 297 | if (kx_init(&p->kx, p, &p->ks)) |
| 298 | goto tidy_0; |
| 299 | if (tun_create(&p->t, p)) |
| 300 | goto tidy_1; |
| 301 | p->next = peers; |
| 302 | if (peers) |
| 303 | peers->prev = p; |
| 304 | peers = p; |
| 305 | return (p); |
| 306 | |
| 307 | tidy_1: |
| 308 | kx_free(&p->kx); |
| 309 | tidy_0: |
| 310 | xfree(p->name); |
| 311 | DESTROY(p); |
| 312 | return (0); |
| 313 | } |
| 314 | |
| 315 | /* --- @p_name@ --- * |
| 316 | * |
| 317 | * Arguments: @peer *p@ = pointer to a peer block |
| 318 | * |
| 319 | * Returns: A pointer to the peer's name. |
| 320 | */ |
| 321 | |
| 322 | const char *p_name(peer *p) { return (p->name); } |
| 323 | |
| 324 | /* --- @p_find@ --- * |
| 325 | * |
| 326 | * Arguments: @const char *name@ = name to look up |
| 327 | * |
| 328 | * Returns: Pointer to the peer block, or null if not found. |
| 329 | * |
| 330 | * Use: Finds a peer by name. |
| 331 | */ |
| 332 | |
| 333 | peer *p_find(const char *name) |
| 334 | { |
| 335 | peer *p; |
| 336 | for (p = peers; p; p = p->next) { |
| 337 | if (strcmp(name, p->name) == 0) |
| 338 | return (p); |
| 339 | } |
| 340 | return (0); |
| 341 | } |
| 342 | |
| 343 | /* --- @p_destroy@ --- * |
| 344 | * |
| 345 | * Arguments: @peer *p@ = pointer to a peer |
| 346 | * |
| 347 | * Returns: --- |
| 348 | * |
| 349 | * Use: Destroys a peer. |
| 350 | */ |
| 351 | |
| 352 | void p_destroy(peer *p) |
| 353 | { |
| 354 | T( trace(T_PEER, "peer: destroying peer `%s'", p->name); ) |
| 355 | ks_free(&p->ks); |
| 356 | kx_free(&p->kx); |
| 357 | tun_destroy(&p->t); |
| 358 | xfree(p->name); |
| 359 | if (p->next) |
| 360 | p->next->prev = p->prev; |
| 361 | if (p->prev) |
| 362 | p->prev->next = p->next; |
| 363 | else |
| 364 | peers = p->next; |
| 365 | DESTROY(p); |
| 366 | } |
| 367 | |
| 368 | /* --- @p_first@, @p_next@ --- * |
| 369 | * |
| 370 | * Arguments: @peer *p@ = a peer block |
| 371 | * |
| 372 | * Returns: @peer_first@ returns the first peer in some ordering; |
| 373 | * @peer_next@ returns the peer following a given one in the |
| 374 | * same ordering. Null is returned for the end of the list. |
| 375 | */ |
| 376 | |
| 377 | peer *p_first(void) { return (peers); } |
| 378 | peer *p_next(peer *p) { return (p->next); } |
| 379 | |
| 380 | /*----- That's all, folks -------------------------------------------------*/ |