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