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