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1 | /* -*-c-*- |
2 | * |
03f996bd |
3 | * $Id: check.c,v 1.2 1997/08/04 10:24:20 mdw Exp $ |
c4f2d992 |
4 | * |
5 | * Check validity of requests |
6 | * |
7 | * (c) 1997 EBI |
8 | */ |
9 | |
03f996bd |
10 | /*----- Licensing notice --------------------------------------------------* |
c4f2d992 |
11 | * |
12 | * This file is part of `become' |
13 | * |
14 | * `Become' 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 | * `Become' 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 |
03f996bd |
25 | * along with `become'; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
c4f2d992 |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: check.c,v $ |
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32 | * Revision 1.2 1997/08/04 10:24:20 mdw |
33 | * Sources placed under CVS control. |
34 | * |
35 | * Revision 1.1 1997/07/21 13:47:53 mdw |
c4f2d992 |
36 | * Initial revision |
37 | * |
38 | */ |
39 | |
40 | /*----- Header files ------------------------------------------------------*/ |
41 | |
42 | /* --- ANSI headers --- */ |
43 | |
44 | #include <ctype.h> |
45 | #include <errno.h> |
46 | #include <stdio.h> |
47 | #include <stdlib.h> |
48 | #include <string.h> |
49 | #include <time.h> |
50 | |
51 | /* --- Unix headers --- */ |
52 | |
53 | #include <sys/time.h> |
54 | #include <sys/types.h> |
55 | #include <sys/socket.h> |
56 | |
57 | #include <netinet/in.h> |
58 | |
59 | #include <arpa/inet.h> |
60 | |
61 | #include <netdb.h> |
62 | #include <unistd.h> |
63 | |
64 | /* --- Local headers --- */ |
65 | |
66 | #include "become.h" |
67 | #include "config.h" |
68 | #include "crypt.h" |
69 | #include "idea.h" |
70 | #include "lexer.h" |
71 | #include "name.h" |
72 | #include "rule.h" |
73 | #include "parser.h" |
74 | #include "tx.h" |
03f996bd |
75 | #include "userdb.h" |
c4f2d992 |
76 | #include "utils.h" |
77 | |
78 | /*----- Main code ---------------------------------------------------------*/ |
79 | |
03f996bd |
80 | /* --- @check__send@ --- * |
81 | * |
82 | * Arguments: @unsigned char *crq@ = pointer to encrypted request |
83 | * @int fd@ = socket to send from |
84 | * @struct sockaddr_in *serv@ = pointer to table of servers |
85 | * @size_t n_serv@ = number of servers |
86 | * |
87 | * Returns: --- |
88 | * |
89 | * Use: Sends the request packet to the list of servers. If the |
90 | * message couldn't be sent to any of them, an error is |
91 | * reported. |
92 | */ |
93 | |
94 | static void check__send(unsigned char *crq, int fd, |
95 | struct sockaddr_in *serv, size_t n_serv) |
96 | { |
97 | size_t i; |
98 | int ok = 0; |
99 | int err = 0; |
100 | |
101 | for (i = 0; i < n_serv; i++) { |
102 | if (sendto(fd, (char *)crq, crq_size, 0, |
103 | (struct sockaddr *)(serv + i), sizeof(serv[i])) < 0) { |
104 | T( trace(TRACE_CLIENT, "client: send to %s failed: %s", |
105 | inet_ntoa(serv[i].sin_addr), strerror(errno)); ) |
106 | err = errno; |
107 | } else |
108 | ok = 1; |
109 | } |
110 | |
111 | if (!ok) |
112 | die("couldn't send request to server: %s", strerror(err)); |
113 | } |
114 | |
115 | /* --- @check__ask@ --- * |
c4f2d992 |
116 | * |
117 | * Arguments: @request *rq@ = pointer to request buffer |
03f996bd |
118 | * @struct sockaddr_in *serv@ = pointer to table of servers |
119 | * @size_t n_serv@ = number of servers |
c4f2d992 |
120 | * |
121 | * Returns: Nonzero if OK, zero if forbidden |
122 | * |
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123 | * Use: Contacts a number of servers to decide whether the request |
124 | * is OK. |
c4f2d992 |
125 | */ |
126 | |
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127 | static int check__ask(request *rq, struct sockaddr_in *serv, size_t n_serv) |
c4f2d992 |
128 | { |
129 | int fd; |
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130 | unsigned char crq[crq_size]; |
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131 | unsigned char sk[IDEA_KEYSIZE]; |
132 | time_t t; |
133 | pid_t pid; |
134 | |
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135 | /* --- First, build the encrypted request packet --- */ |
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136 | |
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137 | { |
138 | unsigned char k[IDEA_KEYSIZE]; |
139 | FILE *fp; |
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140 | |
03f996bd |
141 | /* --- Read in the encryption key --- */ |
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142 | |
03f996bd |
143 | if ((fp = fopen(file_KEY, "r")) == 0) { |
144 | die("couldn't open key file `%s': %s", file_KEY, |
145 | strerror(errno)); |
146 | } |
147 | tx_getBits(k, 128, fp); |
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148 | |
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149 | /* --- Now build a request packet --- */ |
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150 | |
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151 | t = time(0); |
152 | pid = getpid(); |
153 | crypt_packRequest(rq, crq, t, pid, k, sk); |
154 | burn(k); |
155 | T( trace(TRACE_CLIENT, "client: encrypted request packet"); ) |
c4f2d992 |
156 | } |
157 | |
03f996bd |
158 | /* --- Create my socket --- */ |
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159 | |
160 | { |
03f996bd |
161 | struct sockaddr_in sin; |
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162 | |
03f996bd |
163 | if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) |
164 | die("couldn't create socket: %s", strerror(errno)); |
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165 | |
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166 | /* --- Bind myself to some address --- */ |
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167 | |
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168 | sin.sin_family = AF_INET; |
169 | sin.sin_port = 0; |
170 | sin.sin_addr.s_addr = htonl(INADDR_ANY); |
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171 | |
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172 | if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0) |
173 | die("couldn't bind socket to address: %s", strerror(errno)); |
c4f2d992 |
174 | } |
175 | |
03f996bd |
176 | /* --- Now wait for a reply --- */ |
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177 | |
178 | { |
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179 | fd_set fds; |
180 | struct timeval start, now, tv; |
181 | int ind; |
182 | size_t i; |
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183 | |
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184 | /* --- State table for waiting for replies --- * |
185 | * |
186 | * For each number, send off the request to our servers, and wait for |
187 | * that many seconds to have elapsed since we started. If the number is |
188 | * %$-1$% then it's time to give up. |
189 | */ |
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190 | |
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191 | static int tbl[] = { 0, 5, 10, 20, -1 }; |
c4f2d992 |
192 | |
03f996bd |
193 | /* --- Find out when we are --- */ |
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194 | |
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195 | gettimeofday(&start, 0); |
196 | ind = 0; |
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197 | |
03f996bd |
198 | /* --- Now loop until everything's done --- */ |
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199 | |
200 | for (;;) { |
03f996bd |
201 | gettimeofday(&now, 0); |
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202 | |
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203 | /* --- If the current timer has expired, find one that hasn't --- * |
204 | * |
205 | * Also resend the request after I've found a timer which is still |
206 | * extant. If there aren't any, report an error. |
207 | */ |
208 | |
209 | if (now.tv_sec >= start.tv_sec + tbl[ind] && |
210 | now.tv_usec >= start.tv_usec) { |
211 | do { |
212 | ind++; |
213 | if (tbl[ind] < 0) |
214 | die("no reply from servers"); |
215 | } while (now.tv_sec >= start.tv_sec + tbl[ind] && |
216 | now.tv_usec >= start.tv_usec); |
217 | check__send(crq, fd, serv, n_serv); |
218 | T( trace(TRACE_CLIENT, "client: send request to servers"); ) |
219 | } |
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220 | |
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221 | /* --- Now wait for a packet to arrive --- */ |
222 | |
223 | if (now.tv_usec > start.tv_usec) { |
c4f2d992 |
224 | now.tv_usec -= 1000000; |
225 | now.tv_sec += 1; |
226 | } |
03f996bd |
227 | tv.tv_sec = start.tv_sec + tbl[ind] - now.tv_sec; |
228 | tv.tv_usec = start.tv_usec - now.tv_usec; |
c4f2d992 |
229 | |
230 | /* --- Sort out file descriptors to watch --- */ |
231 | |
232 | FD_ZERO(&fds); |
233 | FD_SET(fd, &fds); |
234 | |
235 | /* --- Wait for them --- */ |
236 | |
237 | i = select(FD_SETSIZE, &fds, 0, 0, &tv); |
03f996bd |
238 | if (i == 0 || (i < 0 && errno == EINTR)) |
239 | continue; |
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240 | if (i < 0) |
241 | die("error waiting for reply: %s", strerror(errno)); |
242 | |
243 | /* --- A reply should be waiting now --- */ |
244 | |
245 | { |
246 | struct sockaddr_in sin; |
247 | int slen = sizeof(sin); |
248 | unsigned char buff[256]; |
249 | int answer; |
250 | |
251 | /* --- Read the reply data --- */ |
252 | |
253 | if (recvfrom(fd, (char *)buff, sizeof(buff), 0, |
254 | (struct sockaddr *)&sin, &slen) < 0) |
255 | die("error reading server's reply: %s", strerror(errno)); |
256 | |
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257 | IF_TRACING(TRACE_CLIENT, { |
258 | struct hostent *h = gethostbyaddr((char *)&sin.sin_addr, |
259 | sizeof(sin.sin_addr), AF_INET); |
260 | trace(TRACE_CLIENT, "client: reply received from %s port %i", |
261 | h ? h->h_name : inet_ntoa(sin.sin_addr), |
262 | ntohs(sin.sin_port)); |
263 | }) |
264 | |
265 | /* --- Verify the sender --- * |
266 | * |
267 | * This is more to avoid confusion than for security: an active |
268 | * attacker is quite capable of forging the source address. We rely |
269 | * on the checksum in the reply packet for authentication. |
270 | */ |
271 | |
272 | for (i = 0; i < n_serv; i++) { |
273 | if (sin.sin_addr.s_addr == serv[i].sin_addr.s_addr && |
274 | sin.sin_port == serv[i].sin_port) |
275 | break; |
276 | } |
277 | if (i >= n_serv) { |
278 | T( trace(TRACE_CLIENT, "client: reply from unknown host"); ) |
c4f2d992 |
279 | continue; |
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280 | } |
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281 | |
282 | /* --- Unpack and verify the response --- */ |
283 | |
284 | answer = crypt_unpackReply(buff, sk, t, pid); |
03f996bd |
285 | if (answer < 0) { |
286 | T( trace(TRACE_CLIENT, |
287 | "client: invalid or corrupt reply packet"); ) |
c4f2d992 |
288 | continue; |
03f996bd |
289 | } |
c4f2d992 |
290 | return (answer); |
291 | } |
292 | } |
293 | } |
294 | |
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295 | die("internal error: can't get here in check__ask"); |
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296 | return (0); |
297 | } |
298 | |
03f996bd |
299 | /* --- @check__client@ --- * |
300 | * |
301 | * Arguments: @request *rq@ = pointer to a request block |
302 | * @FILE *fp@ = file containing server configuration |
303 | * |
304 | * Returns: Nonzero if OK, zero if forbidden |
305 | * |
306 | * Use: Asks one or several servers whether a request is acceptable. |
307 | */ |
308 | |
309 | int check__client(request *rq, FILE *fp) |
310 | { |
311 | /* --- Format of the file --- * |
312 | * |
313 | * The `servers' file contains entries of the form |
314 | * |
315 | * %%\syntax{<host> [`:' <port>]}%% |
316 | * |
317 | * separates by whitespace. I build them all into an array of socket |
318 | * addresses and pass the whole lot to another function. |
319 | */ |
320 | |
321 | struct sockaddr_in *serv; /* Array of servers */ |
322 | size_t n_serv, max_serv; /* Number and maximum number */ |
323 | |
324 | /* --- Initialise the server array --- */ |
325 | |
326 | T( trace(TRACE_CLIENT, "client: reading server definitions"); ) |
327 | n_serv = 0; max_serv = 4; /* Four seems reasonable */ |
328 | serv = xmalloc(sizeof(*serv) * max_serv); |
329 | |
330 | /* --- Start reading the file --- */ |
331 | |
332 | { |
333 | char buff[256], *p, *l; /* A buffer and pointers for it */ |
334 | int port; /* Default port for servers */ |
335 | int state; /* Current parser state */ |
336 | struct in_addr t_host; /* Temp place for an address*/ |
337 | int t_port; /* Temp place for a port */ |
338 | int ch; /* The current character */ |
339 | |
340 | /* --- Parser states --- */ |
341 | |
342 | enum { |
343 | st_start, /* Waiting to begin */ |
344 | st_host, /* Reading a new hostname */ |
345 | st_colon, /* Expecting a colon, maybe */ |
346 | st_preport, /* Waiting before reading port */ |
347 | st_port, /* Reading a port number */ |
348 | st_commit, /* Commit a newly read server */ |
349 | st_done /* Finished reading the file */ |
350 | }; |
351 | |
352 | /* --- Find a default port --- */ |
353 | |
354 | { |
355 | struct servent *s = getservbyname(quis(), "udp"); |
356 | port = (s ? s->s_port : -1); |
357 | } |
358 | |
359 | /* --- Initialise for scanning the file --- */ |
360 | |
361 | state = st_host; |
362 | p = buff; |
363 | l = buff + sizeof(buff); |
364 | t_port = port; |
365 | ch = getc(fp); |
366 | |
367 | /* --- Go for it --- */ |
368 | |
369 | while (state != st_done) { |
370 | switch (state) { |
371 | |
372 | /* --- Initial whitespace before hostname --- */ |
373 | |
374 | case st_start: |
375 | if (ch == EOF) |
376 | state = st_done; |
377 | else if (isspace((unsigned char)ch)) |
378 | ch = getc(fp); |
379 | else |
380 | state = st_host; |
381 | break; |
382 | |
383 | /* --- Read a host name --- */ |
384 | |
385 | case st_host: |
386 | if (p == l) |
387 | die("string too long in `" file_SERVER "'"); |
388 | if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { |
389 | *p++ = ch; |
390 | ch = getc(fp); |
391 | } else { |
392 | struct hostent *h; |
393 | |
394 | *p++ = 0; |
395 | if ((h = gethostbyname(buff)) == 0) |
396 | die("unknown host `%s' in `" file_SERVER "'", buff); |
397 | memcpy(&t_host, h->h_addr, sizeof(t_host)); |
398 | state = st_colon; |
399 | } |
400 | break; |
401 | |
402 | /* --- Waiting for a colon coming up --- */ |
403 | |
404 | case st_colon: |
405 | if (ch == EOF) |
406 | state = st_commit; |
407 | else if (isspace((unsigned char)ch)) |
408 | ch = getc(fp); |
409 | else if (ch == ':') { |
410 | state = st_preport; |
411 | ch = getc(fp); |
412 | } |
413 | else |
414 | state = st_commit; |
415 | break; |
416 | |
417 | /* --- Clearing whitespace before a port number --- */ |
418 | |
419 | case st_preport: |
420 | if (ch == EOF) |
421 | state = st_commit; |
422 | else if (isspace((unsigned char)ch)) |
423 | ch = getc(fp); |
424 | else { |
425 | state = st_port; |
426 | p = buff; |
427 | } |
428 | break; |
429 | |
430 | /* --- Read a port number --- */ |
431 | |
432 | case st_port: |
433 | if (p == l) |
434 | die("string too long in `" file_SERVER "'"); |
435 | if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { |
436 | *p++ = ch; |
437 | ch = getc(fp); |
438 | } else { |
439 | struct servent *s; |
440 | |
441 | *p++ = 0; |
442 | s = getservbyname(buff, "udp"); |
443 | if (!s && isdigit((unsigned char)buff[0])) |
444 | t_port = htons(atoi(buff)); |
445 | else if (!s) |
446 | die("unknown service `%s' in `" file_SERVER "'", buff); |
447 | else |
448 | t_port = s->s_port; |
449 | state = st_commit; |
450 | } |
451 | break; |
452 | |
453 | /* --- A server has been read successfully --- */ |
454 | |
455 | case st_commit: |
456 | if (n_serv == max_serv) { |
457 | max_serv *= 2; |
458 | serv = xrealloc(serv, max_serv * sizeof(*serv)); |
459 | } |
460 | serv[n_serv].sin_family = AF_INET; |
461 | serv[n_serv].sin_addr = t_host; |
462 | serv[n_serv].sin_port = t_port; |
463 | n_serv++; |
464 | state = st_start; |
465 | p = buff; |
466 | t_port = port; |
467 | break; |
468 | |
469 | /* --- A safety net for a broken parser --- */ |
470 | |
471 | default: |
472 | die("internal error: can't get here in check__client"); |
473 | break; |
474 | } |
475 | } |
476 | } |
477 | |
478 | fclose(fp); |
479 | |
480 | /* --- Now start sending requests --- */ |
481 | |
482 | if (!n_serv) |
483 | die("no servers specified in `" file_SERVER "'"); |
484 | |
485 | IF_TRACING(TRACE_CLIENT, { |
486 | size_t i; |
487 | |
488 | for (i = 0; i < n_serv; i++) { |
489 | trace(TRACE_CLIENT, "client: server %s port %i", |
490 | inet_ntoa(serv[i].sin_addr), ntohs(serv[i].sin_port)); |
491 | } |
492 | }) |
493 | return (check__ask(rq, serv, n_serv)); |
494 | } |
495 | |
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496 | /* --- @check@ --- * |
497 | * |
498 | * Arguments: @request *rq@ = pointer to request buffer |
499 | * |
500 | * Returns: Nonzero if OK, zero if forbidden |
501 | * |
502 | * Use: Checks to see if the request is acceptable. |
503 | */ |
504 | |
505 | int check(request *rq) |
506 | { |
507 | FILE *fp; |
508 | |
509 | /* --- Check if we need to talk to a server --- */ |
510 | |
03f996bd |
511 | if ((fp = fopen(file_SERVER, "r")) != 0) |
512 | return (check__client(rq, fp)); |
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513 | |
03f996bd |
514 | /* --- Otherwise do this all the old-fashioned way --- */ |
c4f2d992 |
515 | |
516 | if ((fp = fopen(file_RULES, "r")) == 0) { |
517 | die("couldn't read configuration file `%s': %s", |
518 | file_RULES, strerror(errno)); |
519 | } |
520 | |
03f996bd |
521 | userdb_init(); |
522 | userdb_local(); |
523 | userdb_yp(); |
c4f2d992 |
524 | name_init(); |
525 | rule_init(); |
526 | lexer_scan(fp); |
527 | yyparse(); |
528 | |
529 | return (rule_check(rq)); |
530 | } |
531 | |
532 | /*----- That's all, folks -------------------------------------------------*/ |