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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: peer.c,v 1.10 2003/10/15 09:29:38 mdw Exp $ |
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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 $ |
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32 | * Revision 1.10 2003/10/15 09:29:38 mdw |
33 | * Cosmetic fix to changelog comment. |
34 | * |
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35 | * Revision 1.9 2003/07/13 11:19:49 mdw |
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36 | * Incompatible protocol fix! Include message type code under MAC tag to |
37 | * prevent cut-and-paste from key-exchange messages to general packet |
38 | * transport. |
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39 | * |
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40 | * Revision 1.8 2003/05/16 12:09:03 mdw |
41 | * Allow binding to a chosen address. |
42 | * |
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43 | * Revision 1.7 2003/04/15 14:12:05 mdw |
44 | * Insert a newline to improve readability. |
45 | * |
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46 | * Revision 1.6 2001/06/19 22:07:59 mdw |
47 | * Use magic number for packet size. |
48 | * |
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49 | * Revision 1.5 2001/03/03 11:15:19 mdw |
50 | * Set the socket send and receive buffers to maximum. At least this way, |
51 | * we won't drop large packets on the floor. If the administrator wants to |
52 | * prevent fragmentation of TrIPE messages, he can lower the MTU on the |
53 | * tunnel interface. Getting path-MTU stuff out of the kernel is too much |
54 | * system-specific hard work for this program. |
55 | * |
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56 | * Revision 1.4 2001/02/16 21:40:24 mdw |
57 | * Change key exchange message interface. Maintain statistics. |
58 | * |
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59 | * Revision 1.3 2001/02/04 17:10:58 mdw |
60 | * Make file descriptors be nonblocking and close-on-exec. |
61 | * |
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62 | * Revision 1.2 2001/02/03 22:40:29 mdw |
63 | * Put timer information into the entropy pool when packets are received |
64 | * and on similar events. Reseed the generator on the interval timer. |
65 | * |
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66 | * Revision 1.1 2001/02/03 20:26:37 mdw |
67 | * Initial checkin. |
68 | * |
69 | */ |
70 | |
71 | /*----- Header files ------------------------------------------------------*/ |
72 | |
73 | #include "tripe.h" |
74 | |
75 | /*----- Static variables --------------------------------------------------*/ |
76 | |
77 | static peer *peers = 0; |
78 | static sel_file sock; |
79 | |
80 | /*----- Main code ---------------------------------------------------------*/ |
81 | |
82 | /* --- @p_read@ --- * |
83 | * |
84 | * Arguments: @int fd@ = file descriptor to read from |
85 | * @unsigned mode@ = what happened |
86 | * @void *v@ = an uninteresting pointer |
87 | * |
88 | * Returns: --- |
89 | * |
90 | * Use: Reads a packet from somewhere. |
91 | */ |
92 | |
93 | static void p_read(int fd, unsigned mode, void *v) |
94 | { |
95 | peer *p; |
96 | addr a; |
97 | size_t sz; |
98 | ssize_t n; |
99 | int ch; |
100 | buf b, bb; |
101 | |
102 | /* --- Read the data --- */ |
103 | |
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104 | TIMER; |
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105 | sz = sizeof(addr); |
106 | n = recvfrom(fd, buf_i, sizeof(buf_i), 0, &a.sa, &sz); |
107 | if (n < 0) { |
108 | a_warn("error reading socket: %s", strerror(errno)); |
109 | return; |
110 | } |
111 | |
112 | /* --- Find the appropriate peer --- */ |
113 | |
114 | assert(a.sa.sa_family == AF_INET); |
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115 | for (p = peers; p; p = p->next) { |
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116 | if (p->peer.sin.sin_addr.s_addr == a.sin.sin_addr.s_addr && |
117 | p->peer.sin.sin_port == a.sin.sin_port) |
118 | goto found; |
119 | } |
120 | a_warn("packet from unexpected peer: %s:%u", |
121 | inet_ntoa(a.sin.sin_addr), (unsigned)ntohs(a.sin.sin_port)); |
122 | return; |
123 | |
124 | found: |
125 | T( trace(T_PEER, "peer: packet received from `%s'", p->name); |
126 | trace_block(T_PACKET, "peer: packet contents", buf_i, n); ) |
127 | |
128 | /* --- Pick the packet apart --- */ |
129 | |
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130 | p->st.t_last = time(0); |
131 | p->st.n_in++; |
132 | p->st.sz_in += n; |
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133 | buf_init(&b, buf_i, n); |
134 | if ((ch = buf_getbyte(&b)) < 0) { |
135 | a_warn("bad packet from `%s': no type byte", p->name); |
136 | return; |
137 | } |
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138 | switch (ch & MSG_CATMASK) { |
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139 | case MSG_PACKET: |
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140 | if (ch & MSG_TYPEMASK) { |
141 | a_warn("unknown packet type from `%s'", p->name); |
142 | p->st.n_reject++; |
143 | return; |
144 | } |
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145 | buf_init(&bb, buf_o, sizeof(buf_o)); |
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146 | if (ksl_decrypt(&p->ks, MSG_PACKET, &b, &bb)) { |
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147 | p->st.n_reject++; |
148 | a_warn("couldn't decrypt inbound packet from `%s'", p->name); |
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149 | return; |
150 | } |
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151 | if (BOK(&bb)) { |
152 | p->st.n_ipin++; |
153 | p->st.sz_ipin += BSZ(&b); |
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154 | tun_inject(&p->t, &bb); |
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155 | } else { |
156 | p->st.n_reject++; |
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157 | a_warn("packet build failed"); |
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158 | } |
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159 | break; |
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160 | case MSG_KEYEXCH: |
161 | kx_message(&p->kx, ch & MSG_TYPEMASK, &b); |
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162 | break; |
163 | default: |
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164 | p->st.n_reject++; |
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165 | a_warn("bad packet from `%s': unknown packet type", p->name); |
166 | break; |
167 | } |
168 | } |
169 | |
170 | /* --- @p_txstart@ --- * |
171 | * |
172 | * Arguments: @peer *p@ = pointer to peer block |
173 | * @unsigned msg@ = message type code |
174 | * |
175 | * Returns: A pointer to a buffer to write to. |
176 | * |
177 | * Use: Starts sending to a peer. Only one send can happen at a |
178 | * time. |
179 | */ |
180 | |
181 | buf *p_txstart(peer *p, unsigned msg) |
182 | { |
183 | buf_init(&p->b, buf_o, sizeof(buf_o)); |
184 | buf_putbyte(&p->b, msg); |
185 | return (&p->b); |
186 | } |
187 | |
188 | /* --- @p_txend@ --- * |
189 | * |
190 | * Arguments: @peer *p@ = pointer to peer block |
191 | * |
192 | * Returns: --- |
193 | * |
194 | * Use: Sends a packet to the peer. |
195 | */ |
196 | |
197 | void p_txend(peer *p) |
198 | { |
199 | if (!BOK(&p->b)) { |
200 | a_warn("packet build failed"); |
201 | return; |
202 | } |
203 | IF_TRACING(T_PEER, trace_block(T_PACKET, "peer: sending packet", |
204 | BBASE(&p->b), BLEN(&p->b)); ) |
205 | if (sendto(sock.fd, BBASE(&p->b), BLEN(&p->b), |
206 | 0, &p->peer.sa, p->sasz) < 0) |
207 | a_warn("packet send to `%s' failed: %s", p->name, strerror(errno)); |
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208 | else { |
209 | p->st.n_out++; |
210 | p->st.sz_out += BLEN(&p->b); |
211 | } |
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212 | } |
213 | |
214 | /* --- @p_tun@ --- * |
215 | * |
216 | * Arguments: @peer *p@ = pointer to peer block |
217 | * @buf *b@ = buffer containing incoming packet |
218 | * |
219 | * Returns: --- |
220 | * |
221 | * Use: Handles a packet which needs to be sent to a peer. |
222 | */ |
223 | |
224 | void p_tun(peer *p, buf *b) |
225 | { |
226 | buf *bb = p_txstart(p, MSG_PACKET); |
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227 | |
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228 | TIMER; |
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229 | if (ksl_encrypt(&p->ks, MSG_PACKET, b, bb)) |
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230 | kx_start(&p->kx); |
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231 | if (BOK(bb) && BLEN(bb)) { |
232 | p->st.n_ipout++; |
233 | p->st.sz_ipout += BLEN(bb); |
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234 | p_txend(p); |
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235 | } |
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236 | } |
237 | |
238 | /* --- @p_interval@ --- * |
239 | * |
240 | * Arguments: --- |
241 | * |
242 | * Returns: --- |
243 | * |
244 | * Use: Called periodically to do tidying. |
245 | */ |
246 | |
247 | void p_interval(void) |
248 | { |
249 | peer *p, *pp; |
250 | int reload; |
251 | |
252 | reload = km_interval(); |
253 | for (p = peers; p; p = pp) { |
254 | pp = p->next; |
255 | if (reload) |
256 | kx_newkeys(&p->kx); |
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257 | ksl_prune(&p->ks); |
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258 | } |
259 | } |
260 | |
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261 | /* --- @p_stats@ --- * |
262 | * |
263 | * Arguments: @peer *p@ = pointer to a peer block |
264 | * |
265 | * Returns: A pointer to the peer's statistics. |
266 | */ |
267 | |
268 | stats *p_stats(peer *p) { return (&p->st); } |
269 | |
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270 | /* --- @p_ifname@ --- * |
271 | * |
272 | * Arguments: @peer *p@ = pointer to a peer block |
273 | * |
274 | * Returns: A pointer to the peer's interface name. |
275 | */ |
276 | |
277 | const char *p_ifname(peer *p) { return (tun_ifname(&p->t)); } |
278 | |
279 | /* --- @p_addr@ --- * |
280 | * |
281 | * Arguments: @peer *p@ = pointer to a peer block |
282 | * |
283 | * Returns: A pointer to the peer's address. |
284 | */ |
285 | |
286 | const addr *p_addr(peer *p) { return (&p->peer); } |
287 | |
288 | /* --- @p_init@ --- * |
289 | * |
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290 | * Arguments: @struct in_addr addr@ = address to bind to |
291 | * @unsigned port@ = port number to listen to |
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292 | * |
293 | * Returns: --- |
294 | * |
295 | * Use: Initializes the peer system; creates the socket. |
296 | */ |
297 | |
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298 | void p_init(struct in_addr addr, unsigned port) |
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299 | { |
300 | int fd; |
301 | struct sockaddr_in sin; |
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302 | int len = PKBUFSZ; |
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303 | |
304 | /* --- Note on socket buffer sizes --- * |
305 | * |
306 | * For some bizarre reason, Linux 2.2 (at least) doubles the socket buffer |
307 | * sizes I pass to @setsockopt@. I'm not putting special-case code here |
308 | * for Linux: BSD (at least TCPv2) does what I tell it rather than second- |
309 | * guessing me. |
310 | */ |
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311 | |
312 | if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) |
313 | die(EXIT_FAILURE, "socket creation failed: %s", strerror(errno)); |
314 | BURN(sin); |
315 | sin.sin_family = AF_INET; |
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316 | sin.sin_addr = addr; |
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317 | sin.sin_port = htons(port); |
318 | if (bind(fd, (struct sockaddr *)&sin, sizeof(sin))) |
319 | die(EXIT_FAILURE, "bind failed: %s", strerror(errno)); |
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320 | if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) || |
321 | setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len))) { |
322 | die(EXIT_FAILURE, "failed to set socket buffer sizes: %s", |
323 | strerror(errno)); |
324 | } |
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325 | fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC); |
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326 | sel_initfile(&sel, &sock, fd, SEL_READ, p_read, 0); |
327 | sel_addfile(&sock); |
328 | T( trace(T_PEER, "peer: created socket"); ) |
329 | } |
330 | |
331 | /* --- @p_port@ --- * |
332 | * |
333 | * Arguments: --- |
334 | * |
335 | * Returns: Port number used for socket. |
336 | */ |
337 | |
338 | unsigned p_port(void) |
339 | { |
340 | addr a; |
341 | size_t sz = sizeof(addr); |
342 | |
343 | if (getsockname(sock.fd, &a.sa, &sz)) |
344 | die(EXIT_FAILURE, "couldn't read port number: %s", strerror(errno)); |
345 | assert(a.sa.sa_family == AF_INET); |
346 | return (ntohs(a.sin.sin_port)); |
347 | } |
348 | |
349 | /* --- @p_create@ --- * |
350 | * |
351 | * Arguments: @const char *name@ = name for this peer |
352 | * @struct sockaddr *sa@ = socket address of peer |
353 | * @size_t sz@ = size of socket address |
354 | * |
355 | * Returns: Pointer to the peer block, or null if it failed. |
356 | * |
357 | * Use: Creates a new named peer block. No peer is actually attached |
358 | * by this point. |
359 | */ |
360 | |
361 | peer *p_create(const char *name, struct sockaddr *sa, size_t sz) |
362 | { |
363 | peer *p = CREATE(peer); |
364 | T( trace(T_PEER, "peer: creating new peer `%s'", name); ) |
365 | p->name = xstrdup(name); |
366 | p->ks = 0; |
367 | p->prev = 0; |
368 | memcpy(&p->peer.sa, sa, sz); |
369 | p->sasz = sz; |
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370 | memset(&p->st, 0, sizeof(stats)); |
371 | p->st.t_start = time(0); |
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372 | if (kx_init(&p->kx, p, &p->ks)) |
373 | goto tidy_0; |
374 | if (tun_create(&p->t, p)) |
375 | goto tidy_1; |
376 | p->next = peers; |
377 | if (peers) |
378 | peers->prev = p; |
379 | peers = p; |
380 | return (p); |
381 | |
382 | tidy_1: |
383 | kx_free(&p->kx); |
384 | tidy_0: |
385 | xfree(p->name); |
386 | DESTROY(p); |
387 | return (0); |
388 | } |
389 | |
390 | /* --- @p_name@ --- * |
391 | * |
392 | * Arguments: @peer *p@ = pointer to a peer block |
393 | * |
394 | * Returns: A pointer to the peer's name. |
395 | */ |
396 | |
397 | const char *p_name(peer *p) { return (p->name); } |
398 | |
399 | /* --- @p_find@ --- * |
400 | * |
401 | * Arguments: @const char *name@ = name to look up |
402 | * |
403 | * Returns: Pointer to the peer block, or null if not found. |
404 | * |
405 | * Use: Finds a peer by name. |
406 | */ |
407 | |
408 | peer *p_find(const char *name) |
409 | { |
410 | peer *p; |
411 | for (p = peers; p; p = p->next) { |
412 | if (strcmp(name, p->name) == 0) |
413 | return (p); |
414 | } |
415 | return (0); |
416 | } |
417 | |
418 | /* --- @p_destroy@ --- * |
419 | * |
420 | * Arguments: @peer *p@ = pointer to a peer |
421 | * |
422 | * Returns: --- |
423 | * |
424 | * Use: Destroys a peer. |
425 | */ |
426 | |
427 | void p_destroy(peer *p) |
428 | { |
429 | T( trace(T_PEER, "peer: destroying peer `%s'", p->name); ) |
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430 | ksl_free(&p->ks); |
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431 | kx_free(&p->kx); |
432 | tun_destroy(&p->t); |
433 | xfree(p->name); |
434 | if (p->next) |
435 | p->next->prev = p->prev; |
436 | if (p->prev) |
437 | p->prev->next = p->next; |
438 | else |
439 | peers = p->next; |
440 | DESTROY(p); |
441 | } |
442 | |
443 | /* --- @p_first@, @p_next@ --- * |
444 | * |
445 | * Arguments: @peer *p@ = a peer block |
446 | * |
447 | * Returns: @peer_first@ returns the first peer in some ordering; |
448 | * @peer_next@ returns the peer following a given one in the |
449 | * same ordering. Null is returned for the end of the list. |
450 | */ |
451 | |
452 | peer *p_first(void) { return (peers); } |
453 | peer *p_next(peer *p) { return (p->next); } |
454 | |
455 | /*----- That's all, folks -------------------------------------------------*/ |