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