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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: peer.c,v 1.5 2001/03/03 11:15:19 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 1.5 2001/03/03 11:15:19 mdw |
33 | * Set the socket send and receive buffers to maximum. At least this way, |
34 | * we won't drop large packets on the floor. If the administrator wants to |
35 | * prevent fragmentation of TrIPE messages, he can lower the MTU on the |
36 | * tunnel interface. Getting path-MTU stuff out of the kernel is too much |
37 | * system-specific hard work for this program. |
38 | * |
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39 | * Revision 1.4 2001/02/16 21:40:24 mdw |
40 | * Change key exchange message interface. Maintain statistics. |
41 | * |
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42 | * Revision 1.3 2001/02/04 17:10:58 mdw |
43 | * Make file descriptors be nonblocking and close-on-exec. |
44 | * |
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45 | * Revision 1.2 2001/02/03 22:40:29 mdw |
46 | * Put timer information into the entropy pool when packets are received |
47 | * and on similar events. Reseed the generator on the interval timer. |
48 | * |
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49 | * Revision 1.1 2001/02/03 20:26:37 mdw |
50 | * Initial checkin. |
51 | * |
52 | */ |
53 | |
54 | /*----- Header files ------------------------------------------------------*/ |
55 | |
56 | #include "tripe.h" |
57 | |
58 | /*----- Static variables --------------------------------------------------*/ |
59 | |
60 | static peer *peers = 0; |
61 | static sel_file sock; |
62 | |
63 | /*----- Main code ---------------------------------------------------------*/ |
64 | |
65 | /* --- @p_read@ --- * |
66 | * |
67 | * Arguments: @int fd@ = file descriptor to read from |
68 | * @unsigned mode@ = what happened |
69 | * @void *v@ = an uninteresting pointer |
70 | * |
71 | * Returns: --- |
72 | * |
73 | * Use: Reads a packet from somewhere. |
74 | */ |
75 | |
76 | static void p_read(int fd, unsigned mode, void *v) |
77 | { |
78 | peer *p; |
79 | addr a; |
80 | size_t sz; |
81 | ssize_t n; |
82 | int ch; |
83 | buf b, bb; |
84 | |
85 | /* --- Read the data --- */ |
86 | |
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87 | TIMER; |
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88 | sz = sizeof(addr); |
89 | n = recvfrom(fd, buf_i, sizeof(buf_i), 0, &a.sa, &sz); |
90 | if (n < 0) { |
91 | a_warn("error reading socket: %s", strerror(errno)); |
92 | return; |
93 | } |
94 | |
95 | /* --- Find the appropriate peer --- */ |
96 | |
97 | assert(a.sa.sa_family == AF_INET); |
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98 | for (p = peers; p; p = p->next) { |
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99 | if (p->peer.sin.sin_addr.s_addr == a.sin.sin_addr.s_addr && |
100 | p->peer.sin.sin_port == a.sin.sin_port) |
101 | goto found; |
102 | } |
103 | a_warn("packet from unexpected peer: %s:%u", |
104 | inet_ntoa(a.sin.sin_addr), (unsigned)ntohs(a.sin.sin_port)); |
105 | return; |
106 | |
107 | found: |
108 | T( trace(T_PEER, "peer: packet received from `%s'", p->name); |
109 | trace_block(T_PACKET, "peer: packet contents", buf_i, n); ) |
110 | |
111 | /* --- Pick the packet apart --- */ |
112 | |
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113 | p->st.t_last = time(0); |
114 | p->st.n_in++; |
115 | p->st.sz_in += n; |
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116 | buf_init(&b, buf_i, n); |
117 | if ((ch = buf_getbyte(&b)) < 0) { |
118 | a_warn("bad packet from `%s': no type byte", p->name); |
119 | return; |
120 | } |
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121 | switch (ch & MSG_CATMASK) { |
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122 | case MSG_PACKET: |
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123 | if (ch & MSG_TYPEMASK) { |
124 | a_warn("unknown packet type from `%s'", p->name); |
125 | p->st.n_reject++; |
126 | return; |
127 | } |
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128 | buf_init(&bb, buf_o, sizeof(buf_o)); |
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129 | if (ksl_decrypt(&p->ks, &b, &bb)) { |
130 | p->st.n_reject++; |
131 | a_warn("couldn't decrypt inbound packet from `%s'", p->name); |
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132 | return; |
133 | } |
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134 | if (BOK(&bb)) { |
135 | p->st.n_ipin++; |
136 | p->st.sz_ipin += BSZ(&b); |
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137 | tun_inject(&p->t, &bb); |
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138 | } else { |
139 | p->st.n_reject++; |
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140 | a_warn("packet build failed"); |
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141 | } |
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142 | break; |
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143 | case MSG_KEYEXCH: |
144 | kx_message(&p->kx, ch & MSG_TYPEMASK, &b); |
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145 | break; |
146 | default: |
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147 | p->st.n_reject++; |
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148 | a_warn("bad packet from `%s': unknown packet type", p->name); |
149 | break; |
150 | } |
151 | } |
152 | |
153 | /* --- @p_txstart@ --- * |
154 | * |
155 | * Arguments: @peer *p@ = pointer to peer block |
156 | * @unsigned msg@ = message type code |
157 | * |
158 | * Returns: A pointer to a buffer to write to. |
159 | * |
160 | * Use: Starts sending to a peer. Only one send can happen at a |
161 | * time. |
162 | */ |
163 | |
164 | buf *p_txstart(peer *p, unsigned msg) |
165 | { |
166 | buf_init(&p->b, buf_o, sizeof(buf_o)); |
167 | buf_putbyte(&p->b, msg); |
168 | return (&p->b); |
169 | } |
170 | |
171 | /* --- @p_txend@ --- * |
172 | * |
173 | * Arguments: @peer *p@ = pointer to peer block |
174 | * |
175 | * Returns: --- |
176 | * |
177 | * Use: Sends a packet to the peer. |
178 | */ |
179 | |
180 | void p_txend(peer *p) |
181 | { |
182 | if (!BOK(&p->b)) { |
183 | a_warn("packet build failed"); |
184 | return; |
185 | } |
186 | IF_TRACING(T_PEER, trace_block(T_PACKET, "peer: sending packet", |
187 | BBASE(&p->b), BLEN(&p->b)); ) |
188 | if (sendto(sock.fd, BBASE(&p->b), BLEN(&p->b), |
189 | 0, &p->peer.sa, p->sasz) < 0) |
190 | a_warn("packet send to `%s' failed: %s", p->name, strerror(errno)); |
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191 | else { |
192 | p->st.n_out++; |
193 | p->st.sz_out += BLEN(&p->b); |
194 | } |
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195 | } |
196 | |
197 | /* --- @p_tun@ --- * |
198 | * |
199 | * Arguments: @peer *p@ = pointer to peer block |
200 | * @buf *b@ = buffer containing incoming packet |
201 | * |
202 | * Returns: --- |
203 | * |
204 | * Use: Handles a packet which needs to be sent to a peer. |
205 | */ |
206 | |
207 | void p_tun(peer *p, buf *b) |
208 | { |
209 | buf *bb = p_txstart(p, MSG_PACKET); |
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210 | TIMER; |
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211 | if (ksl_encrypt(&p->ks, b, bb)) |
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212 | kx_start(&p->kx); |
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213 | if (BOK(bb) && BLEN(bb)) { |
214 | p->st.n_ipout++; |
215 | p->st.sz_ipout += BLEN(bb); |
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216 | p_txend(p); |
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217 | } |
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218 | } |
219 | |
220 | /* --- @p_interval@ --- * |
221 | * |
222 | * Arguments: --- |
223 | * |
224 | * Returns: --- |
225 | * |
226 | * Use: Called periodically to do tidying. |
227 | */ |
228 | |
229 | void p_interval(void) |
230 | { |
231 | peer *p, *pp; |
232 | int reload; |
233 | |
234 | reload = km_interval(); |
235 | for (p = peers; p; p = pp) { |
236 | pp = p->next; |
237 | if (reload) |
238 | kx_newkeys(&p->kx); |
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239 | ksl_prune(&p->ks); |
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240 | } |
241 | } |
242 | |
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243 | /* --- @p_stats@ --- * |
244 | * |
245 | * Arguments: @peer *p@ = pointer to a peer block |
246 | * |
247 | * Returns: A pointer to the peer's statistics. |
248 | */ |
249 | |
250 | stats *p_stats(peer *p) { return (&p->st); } |
251 | |
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252 | /* --- @p_ifname@ --- * |
253 | * |
254 | * Arguments: @peer *p@ = pointer to a peer block |
255 | * |
256 | * Returns: A pointer to the peer's interface name. |
257 | */ |
258 | |
259 | const char *p_ifname(peer *p) { return (tun_ifname(&p->t)); } |
260 | |
261 | /* --- @p_addr@ --- * |
262 | * |
263 | * Arguments: @peer *p@ = pointer to a peer block |
264 | * |
265 | * Returns: A pointer to the peer's address. |
266 | */ |
267 | |
268 | const addr *p_addr(peer *p) { return (&p->peer); } |
269 | |
270 | /* --- @p_init@ --- * |
271 | * |
272 | * Arguments: @unsigned port@ = port number to listen to |
273 | * |
274 | * Returns: --- |
275 | * |
276 | * Use: Initializes the peer system; creates the socket. |
277 | */ |
278 | |
279 | void p_init(unsigned port) |
280 | { |
281 | int fd; |
282 | struct sockaddr_in sin; |
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283 | int len = 65536; |
284 | |
285 | /* --- Note on socket buffer sizes --- * |
286 | * |
287 | * For some bizarre reason, Linux 2.2 (at least) doubles the socket buffer |
288 | * sizes I pass to @setsockopt@. I'm not putting special-case code here |
289 | * for Linux: BSD (at least TCPv2) does what I tell it rather than second- |
290 | * guessing me. |
291 | */ |
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292 | |
293 | if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) |
294 | die(EXIT_FAILURE, "socket creation failed: %s", strerror(errno)); |
295 | BURN(sin); |
296 | sin.sin_family = AF_INET; |
297 | sin.sin_addr.s_addr = INADDR_ANY; |
298 | sin.sin_port = htons(port); |
299 | if (bind(fd, (struct sockaddr *)&sin, sizeof(sin))) |
300 | die(EXIT_FAILURE, "bind failed: %s", strerror(errno)); |
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301 | if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) || |
302 | setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len))) { |
303 | die(EXIT_FAILURE, "failed to set socket buffer sizes: %s", |
304 | strerror(errno)); |
305 | } |
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306 | fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC); |
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307 | sel_initfile(&sel, &sock, fd, SEL_READ, p_read, 0); |
308 | sel_addfile(&sock); |
309 | T( trace(T_PEER, "peer: created socket"); ) |
310 | } |
311 | |
312 | /* --- @p_port@ --- * |
313 | * |
314 | * Arguments: --- |
315 | * |
316 | * Returns: Port number used for socket. |
317 | */ |
318 | |
319 | unsigned p_port(void) |
320 | { |
321 | addr a; |
322 | size_t sz = sizeof(addr); |
323 | |
324 | if (getsockname(sock.fd, &a.sa, &sz)) |
325 | die(EXIT_FAILURE, "couldn't read port number: %s", strerror(errno)); |
326 | assert(a.sa.sa_family == AF_INET); |
327 | return (ntohs(a.sin.sin_port)); |
328 | } |
329 | |
330 | /* --- @p_create@ --- * |
331 | * |
332 | * Arguments: @const char *name@ = name for this peer |
333 | * @struct sockaddr *sa@ = socket address of peer |
334 | * @size_t sz@ = size of socket address |
335 | * |
336 | * Returns: Pointer to the peer block, or null if it failed. |
337 | * |
338 | * Use: Creates a new named peer block. No peer is actually attached |
339 | * by this point. |
340 | */ |
341 | |
342 | peer *p_create(const char *name, struct sockaddr *sa, size_t sz) |
343 | { |
344 | peer *p = CREATE(peer); |
345 | T( trace(T_PEER, "peer: creating new peer `%s'", name); ) |
346 | p->name = xstrdup(name); |
347 | p->ks = 0; |
348 | p->prev = 0; |
349 | memcpy(&p->peer.sa, sa, sz); |
350 | p->sasz = sz; |
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351 | memset(&p->st, 0, sizeof(stats)); |
352 | p->st.t_start = time(0); |
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353 | if (kx_init(&p->kx, p, &p->ks)) |
354 | goto tidy_0; |
355 | if (tun_create(&p->t, p)) |
356 | goto tidy_1; |
357 | p->next = peers; |
358 | if (peers) |
359 | peers->prev = p; |
360 | peers = p; |
361 | return (p); |
362 | |
363 | tidy_1: |
364 | kx_free(&p->kx); |
365 | tidy_0: |
366 | xfree(p->name); |
367 | DESTROY(p); |
368 | return (0); |
369 | } |
370 | |
371 | /* --- @p_name@ --- * |
372 | * |
373 | * Arguments: @peer *p@ = pointer to a peer block |
374 | * |
375 | * Returns: A pointer to the peer's name. |
376 | */ |
377 | |
378 | const char *p_name(peer *p) { return (p->name); } |
379 | |
380 | /* --- @p_find@ --- * |
381 | * |
382 | * Arguments: @const char *name@ = name to look up |
383 | * |
384 | * Returns: Pointer to the peer block, or null if not found. |
385 | * |
386 | * Use: Finds a peer by name. |
387 | */ |
388 | |
389 | peer *p_find(const char *name) |
390 | { |
391 | peer *p; |
392 | for (p = peers; p; p = p->next) { |
393 | if (strcmp(name, p->name) == 0) |
394 | return (p); |
395 | } |
396 | return (0); |
397 | } |
398 | |
399 | /* --- @p_destroy@ --- * |
400 | * |
401 | * Arguments: @peer *p@ = pointer to a peer |
402 | * |
403 | * Returns: --- |
404 | * |
405 | * Use: Destroys a peer. |
406 | */ |
407 | |
408 | void p_destroy(peer *p) |
409 | { |
410 | T( trace(T_PEER, "peer: destroying peer `%s'", p->name); ) |
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411 | ksl_free(&p->ks); |
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412 | kx_free(&p->kx); |
413 | tun_destroy(&p->t); |
414 | xfree(p->name); |
415 | if (p->next) |
416 | p->next->prev = p->prev; |
417 | if (p->prev) |
418 | p->prev->next = p->next; |
419 | else |
420 | peers = p->next; |
421 | DESTROY(p); |
422 | } |
423 | |
424 | /* --- @p_first@, @p_next@ --- * |
425 | * |
426 | * Arguments: @peer *p@ = a peer block |
427 | * |
428 | * Returns: @peer_first@ returns the first peer in some ordering; |
429 | * @peer_next@ returns the peer following a given one in the |
430 | * same ordering. Null is returned for the end of the list. |
431 | */ |
432 | |
433 | peer *p_first(void) { return (peers); } |
434 | peer *p_next(peer *p) { return (p->next); } |
435 | |
436 | /*----- That's all, folks -------------------------------------------------*/ |