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