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1 | /* -*-c-*- |
2 | * |
318c0b91 |
3 | * $Id: check.c,v 1.7 1998/04/23 13:22:08 mdw Exp $ |
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4 | * |
5 | * Check validity of requests |
6 | * |
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7 | * (c) 1998 EBI |
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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 $ |
318c0b91 |
32 | * Revision 1.7 1998/04/23 13:22:08 mdw |
33 | * Support no-network configuration option, and new interface to |
34 | * configuration file parser. |
35 | * |
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36 | * Revision 1.6 1998/01/12 16:45:47 mdw |
37 | * Fix copyright date. |
38 | * |
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39 | * Revision 1.5 1997/09/26 09:14:58 mdw |
40 | * Merged blowfish branch into trunk. |
41 | * |
42 | * Revision 1.4.2.1 1997/09/26 09:08:01 mdw |
43 | * Use the Blowfish encryption algorithm instead of IDEA. This is partly |
44 | * because I prefer Blowfish (without any particularly strong evidence) but |
45 | * mainly because IDEA is patented and Blowfish isn't. |
46 | * |
27d7bfc2 |
47 | * Revision 1.4 1997/08/07 09:52:05 mdw |
48 | * (Log entry for previous version is bogus.) Added support for multiple |
49 | * servers. |
607937a4 |
50 | * |
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51 | * Revision 1.2 1997/08/04 10:24:20 mdw |
52 | * Sources placed under CVS control. |
53 | * |
54 | * Revision 1.1 1997/07/21 13:47:53 mdw |
c4f2d992 |
55 | * Initial revision |
56 | * |
57 | */ |
58 | |
59 | /*----- Header files ------------------------------------------------------*/ |
60 | |
61 | /* --- ANSI headers --- */ |
62 | |
63 | #include <ctype.h> |
64 | #include <errno.h> |
65 | #include <stdio.h> |
66 | #include <stdlib.h> |
67 | #include <string.h> |
68 | #include <time.h> |
69 | |
70 | /* --- Unix headers --- */ |
71 | |
72 | #include <sys/time.h> |
73 | #include <sys/types.h> |
74 | #include <sys/socket.h> |
75 | |
76 | #include <netinet/in.h> |
77 | |
78 | #include <arpa/inet.h> |
79 | |
80 | #include <netdb.h> |
81 | #include <unistd.h> |
82 | |
83 | /* --- Local headers --- */ |
84 | |
85 | #include "become.h" |
9e5602f0 |
86 | #include "blowfish.h" |
c4f2d992 |
87 | #include "config.h" |
88 | #include "crypt.h" |
c4f2d992 |
89 | #include "lexer.h" |
90 | #include "name.h" |
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91 | #include "netg.h" |
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92 | #include "rule.h" |
93 | #include "parser.h" |
94 | #include "tx.h" |
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95 | #include "userdb.h" |
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96 | #include "utils.h" |
97 | |
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98 | /*----- Client-end network support ----------------------------------------*/ |
99 | |
100 | #ifndef NONETWORK |
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101 | |
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102 | /* --- @check__send@ --- * |
103 | * |
104 | * Arguments: @unsigned char *crq@ = pointer to encrypted request |
105 | * @int fd@ = socket to send from |
106 | * @struct sockaddr_in *serv@ = pointer to table of servers |
107 | * @size_t n_serv@ = number of servers |
108 | * |
109 | * Returns: --- |
110 | * |
111 | * Use: Sends the request packet to the list of servers. If the |
112 | * message couldn't be sent to any of them, an error is |
113 | * reported. |
114 | */ |
115 | |
116 | static void check__send(unsigned char *crq, int fd, |
117 | struct sockaddr_in *serv, size_t n_serv) |
118 | { |
119 | size_t i; |
120 | int ok = 0; |
121 | int err = 0; |
122 | |
123 | for (i = 0; i < n_serv; i++) { |
124 | if (sendto(fd, (char *)crq, crq_size, 0, |
125 | (struct sockaddr *)(serv + i), sizeof(serv[i])) < 0) { |
126 | T( trace(TRACE_CLIENT, "client: send to %s failed: %s", |
127 | inet_ntoa(serv[i].sin_addr), strerror(errno)); ) |
128 | err = errno; |
129 | } else |
130 | ok = 1; |
131 | } |
132 | |
133 | if (!ok) |
134 | die("couldn't send request to server: %s", strerror(err)); |
135 | } |
136 | |
137 | /* --- @check__ask@ --- * |
c4f2d992 |
138 | * |
139 | * Arguments: @request *rq@ = pointer to request buffer |
03f996bd |
140 | * @struct sockaddr_in *serv@ = pointer to table of servers |
141 | * @size_t n_serv@ = number of servers |
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142 | * |
143 | * Returns: Nonzero if OK, zero if forbidden |
144 | * |
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145 | * Use: Contacts a number of servers to decide whether the request |
146 | * is OK. |
c4f2d992 |
147 | */ |
148 | |
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149 | static int check__ask(request *rq, struct sockaddr_in *serv, size_t n_serv) |
c4f2d992 |
150 | { |
151 | int fd; |
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152 | unsigned char crq[crq_size]; |
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153 | unsigned char sk[BLOWFISH_KEYSIZE]; |
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154 | time_t t; |
155 | pid_t pid; |
156 | |
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157 | /* --- First, build the encrypted request packet --- */ |
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158 | |
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159 | { |
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160 | unsigned char k[BLOWFISH_KEYSIZE]; |
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161 | FILE *fp; |
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162 | |
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163 | /* --- Read in the encryption key --- */ |
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164 | |
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165 | if ((fp = fopen(file_KEY, "r")) == 0) { |
166 | die("couldn't open key file `%s': %s", file_KEY, |
167 | strerror(errno)); |
168 | } |
169 | tx_getBits(k, 128, fp); |
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170 | |
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171 | /* --- Now build a request packet --- */ |
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172 | |
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173 | t = time(0); |
174 | pid = getpid(); |
175 | crypt_packRequest(rq, crq, t, pid, k, sk); |
176 | burn(k); |
177 | T( trace(TRACE_CLIENT, "client: encrypted request packet"); ) |
c4f2d992 |
178 | } |
179 | |
03f996bd |
180 | /* --- Create my socket --- */ |
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181 | |
182 | { |
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183 | struct sockaddr_in sin; |
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184 | |
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185 | if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) |
186 | die("couldn't create socket: %s", strerror(errno)); |
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187 | |
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188 | /* --- Bind myself to some address --- */ |
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189 | |
03f996bd |
190 | sin.sin_family = AF_INET; |
191 | sin.sin_port = 0; |
192 | sin.sin_addr.s_addr = htonl(INADDR_ANY); |
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193 | |
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194 | if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0) |
195 | die("couldn't bind socket to address: %s", strerror(errno)); |
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196 | } |
197 | |
03f996bd |
198 | /* --- Now wait for a reply --- */ |
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199 | |
200 | { |
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201 | fd_set fds; |
202 | struct timeval start, now, tv; |
203 | int ind; |
204 | size_t i; |
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205 | |
03f996bd |
206 | /* --- State table for waiting for replies --- * |
207 | * |
208 | * For each number, send off the request to our servers, and wait for |
209 | * that many seconds to have elapsed since we started. If the number is |
210 | * %$-1$% then it's time to give up. |
211 | */ |
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212 | |
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213 | static int tbl[] = { 0, 5, 10, 20, -1 }; |
c4f2d992 |
214 | |
03f996bd |
215 | /* --- Find out when we are --- */ |
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216 | |
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217 | gettimeofday(&start, 0); |
218 | ind = 0; |
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219 | |
03f996bd |
220 | /* --- Now loop until everything's done --- */ |
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221 | |
222 | for (;;) { |
03f996bd |
223 | gettimeofday(&now, 0); |
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224 | |
03f996bd |
225 | /* --- If the current timer has expired, find one that hasn't --- * |
226 | * |
227 | * Also resend the request after I've found a timer which is still |
228 | * extant. If there aren't any, report an error. |
229 | */ |
230 | |
231 | if (now.tv_sec >= start.tv_sec + tbl[ind] && |
232 | now.tv_usec >= start.tv_usec) { |
233 | do { |
234 | ind++; |
235 | if (tbl[ind] < 0) |
236 | die("no reply from servers"); |
237 | } while (now.tv_sec >= start.tv_sec + tbl[ind] && |
238 | now.tv_usec >= start.tv_usec); |
239 | check__send(crq, fd, serv, n_serv); |
240 | T( trace(TRACE_CLIENT, "client: send request to servers"); ) |
241 | } |
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242 | |
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243 | /* --- Now wait for a packet to arrive --- */ |
244 | |
245 | if (now.tv_usec > start.tv_usec) { |
c4f2d992 |
246 | now.tv_usec -= 1000000; |
247 | now.tv_sec += 1; |
248 | } |
03f996bd |
249 | tv.tv_sec = start.tv_sec + tbl[ind] - now.tv_sec; |
250 | tv.tv_usec = start.tv_usec - now.tv_usec; |
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251 | |
252 | /* --- Sort out file descriptors to watch --- */ |
253 | |
254 | FD_ZERO(&fds); |
255 | FD_SET(fd, &fds); |
256 | |
257 | /* --- Wait for them --- */ |
258 | |
259 | i = select(FD_SETSIZE, &fds, 0, 0, &tv); |
03f996bd |
260 | if (i == 0 || (i < 0 && errno == EINTR)) |
261 | continue; |
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262 | if (i < 0) |
263 | die("error waiting for reply: %s", strerror(errno)); |
264 | |
265 | /* --- A reply should be waiting now --- */ |
266 | |
267 | { |
268 | struct sockaddr_in sin; |
269 | int slen = sizeof(sin); |
270 | unsigned char buff[256]; |
271 | int answer; |
272 | |
273 | /* --- Read the reply data --- */ |
274 | |
275 | if (recvfrom(fd, (char *)buff, sizeof(buff), 0, |
276 | (struct sockaddr *)&sin, &slen) < 0) |
277 | die("error reading server's reply: %s", strerror(errno)); |
278 | |
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279 | IF_TRACING(TRACE_CLIENT, { |
280 | struct hostent *h = gethostbyaddr((char *)&sin.sin_addr, |
281 | sizeof(sin.sin_addr), AF_INET); |
282 | trace(TRACE_CLIENT, "client: reply received from %s port %i", |
283 | h ? h->h_name : inet_ntoa(sin.sin_addr), |
284 | ntohs(sin.sin_port)); |
285 | }) |
286 | |
287 | /* --- Verify the sender --- * |
288 | * |
289 | * This is more to avoid confusion than for security: an active |
290 | * attacker is quite capable of forging the source address. We rely |
291 | * on the checksum in the reply packet for authentication. |
292 | */ |
293 | |
294 | for (i = 0; i < n_serv; i++) { |
295 | if (sin.sin_addr.s_addr == serv[i].sin_addr.s_addr && |
296 | sin.sin_port == serv[i].sin_port) |
297 | break; |
298 | } |
299 | if (i >= n_serv) { |
300 | T( trace(TRACE_CLIENT, "client: reply from unknown host"); ) |
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301 | continue; |
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302 | } |
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303 | |
304 | /* --- Unpack and verify the response --- */ |
305 | |
306 | answer = crypt_unpackReply(buff, sk, t, pid); |
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307 | if (answer < 0) { |
308 | T( trace(TRACE_CLIENT, |
309 | "client: invalid or corrupt reply packet"); ) |
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310 | continue; |
03f996bd |
311 | } |
c4f2d992 |
312 | return (answer); |
313 | } |
314 | } |
315 | } |
316 | |
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317 | die("internal error: can't get here in check__ask"); |
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318 | return (0); |
319 | } |
320 | |
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321 | /* --- @check__client@ --- * |
322 | * |
323 | * Arguments: @request *rq@ = pointer to a request block |
324 | * @FILE *fp@ = file containing server configuration |
325 | * |
326 | * Returns: Nonzero if OK, zero if forbidden |
327 | * |
328 | * Use: Asks one or several servers whether a request is acceptable. |
329 | */ |
330 | |
331 | int check__client(request *rq, FILE *fp) |
332 | { |
333 | /* --- Format of the file --- * |
334 | * |
335 | * The `servers' file contains entries of the form |
336 | * |
337 | * %%\syntax{<host> [`:' <port>]}%% |
338 | * |
339 | * separates by whitespace. I build them all into an array of socket |
340 | * addresses and pass the whole lot to another function. |
341 | */ |
342 | |
343 | struct sockaddr_in *serv; /* Array of servers */ |
344 | size_t n_serv, max_serv; /* Number and maximum number */ |
345 | |
346 | /* --- Initialise the server array --- */ |
347 | |
348 | T( trace(TRACE_CLIENT, "client: reading server definitions"); ) |
349 | n_serv = 0; max_serv = 4; /* Four seems reasonable */ |
350 | serv = xmalloc(sizeof(*serv) * max_serv); |
351 | |
352 | /* --- Start reading the file --- */ |
353 | |
354 | { |
355 | char buff[256], *p, *l; /* A buffer and pointers for it */ |
356 | int port; /* Default port for servers */ |
357 | int state; /* Current parser state */ |
358 | struct in_addr t_host; /* Temp place for an address*/ |
359 | int t_port; /* Temp place for a port */ |
360 | int ch; /* The current character */ |
361 | |
362 | /* --- Parser states --- */ |
363 | |
364 | enum { |
365 | st_start, /* Waiting to begin */ |
366 | st_host, /* Reading a new hostname */ |
367 | st_colon, /* Expecting a colon, maybe */ |
368 | st_preport, /* Waiting before reading port */ |
369 | st_port, /* Reading a port number */ |
370 | st_commit, /* Commit a newly read server */ |
371 | st_done /* Finished reading the file */ |
372 | }; |
373 | |
374 | /* --- Find a default port --- */ |
375 | |
376 | { |
377 | struct servent *s = getservbyname(quis(), "udp"); |
378 | port = (s ? s->s_port : -1); |
379 | } |
380 | |
381 | /* --- Initialise for scanning the file --- */ |
382 | |
383 | state = st_host; |
384 | p = buff; |
385 | l = buff + sizeof(buff); |
386 | t_port = port; |
387 | ch = getc(fp); |
388 | |
389 | /* --- Go for it --- */ |
390 | |
391 | while (state != st_done) { |
392 | switch (state) { |
393 | |
394 | /* --- Initial whitespace before hostname --- */ |
395 | |
396 | case st_start: |
397 | if (ch == EOF) |
398 | state = st_done; |
399 | else if (isspace((unsigned char)ch)) |
400 | ch = getc(fp); |
401 | else |
402 | state = st_host; |
403 | break; |
404 | |
405 | /* --- Read a host name --- */ |
406 | |
407 | case st_host: |
408 | if (p == l) |
409 | die("string too long in `" file_SERVER "'"); |
410 | if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { |
411 | *p++ = ch; |
412 | ch = getc(fp); |
413 | } else { |
414 | struct hostent *h; |
415 | |
416 | *p++ = 0; |
417 | if ((h = gethostbyname(buff)) == 0) |
418 | die("unknown host `%s' in `" file_SERVER "'", buff); |
419 | memcpy(&t_host, h->h_addr, sizeof(t_host)); |
420 | state = st_colon; |
421 | } |
422 | break; |
423 | |
424 | /* --- Waiting for a colon coming up --- */ |
425 | |
426 | case st_colon: |
427 | if (ch == EOF) |
428 | state = st_commit; |
429 | else if (isspace((unsigned char)ch)) |
430 | ch = getc(fp); |
431 | else if (ch == ':') { |
432 | state = st_preport; |
433 | ch = getc(fp); |
434 | } |
435 | else |
436 | state = st_commit; |
437 | break; |
438 | |
439 | /* --- Clearing whitespace before a port number --- */ |
440 | |
441 | case st_preport: |
442 | if (ch == EOF) |
443 | state = st_commit; |
444 | else if (isspace((unsigned char)ch)) |
445 | ch = getc(fp); |
446 | else { |
447 | state = st_port; |
448 | p = buff; |
449 | } |
450 | break; |
451 | |
452 | /* --- Read a port number --- */ |
453 | |
454 | case st_port: |
455 | if (p == l) |
456 | die("string too long in `" file_SERVER "'"); |
457 | if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { |
458 | *p++ = ch; |
459 | ch = getc(fp); |
460 | } else { |
461 | struct servent *s; |
462 | |
463 | *p++ = 0; |
464 | s = getservbyname(buff, "udp"); |
465 | if (!s && isdigit((unsigned char)buff[0])) |
466 | t_port = htons(atoi(buff)); |
467 | else if (!s) |
468 | die("unknown service `%s' in `" file_SERVER "'", buff); |
469 | else |
470 | t_port = s->s_port; |
471 | state = st_commit; |
472 | } |
473 | break; |
474 | |
475 | /* --- A server has been read successfully --- */ |
476 | |
477 | case st_commit: |
478 | if (n_serv == max_serv) { |
479 | max_serv *= 2; |
480 | serv = xrealloc(serv, max_serv * sizeof(*serv)); |
481 | } |
482 | serv[n_serv].sin_family = AF_INET; |
483 | serv[n_serv].sin_addr = t_host; |
484 | serv[n_serv].sin_port = t_port; |
485 | n_serv++; |
486 | state = st_start; |
487 | p = buff; |
488 | t_port = port; |
489 | break; |
490 | |
491 | /* --- A safety net for a broken parser --- */ |
492 | |
493 | default: |
494 | die("internal error: can't get here in check__client"); |
495 | break; |
496 | } |
497 | } |
498 | } |
499 | |
500 | fclose(fp); |
501 | |
502 | /* --- Now start sending requests --- */ |
503 | |
504 | if (!n_serv) |
505 | die("no servers specified in `" file_SERVER "'"); |
506 | |
507 | IF_TRACING(TRACE_CLIENT, { |
508 | size_t i; |
509 | |
510 | for (i = 0; i < n_serv; i++) { |
511 | trace(TRACE_CLIENT, "client: server %s port %i", |
512 | inet_ntoa(serv[i].sin_addr), ntohs(serv[i].sin_port)); |
513 | } |
514 | }) |
515 | return (check__ask(rq, serv, n_serv)); |
516 | } |
517 | |
318c0b91 |
518 | #endif |
519 | |
520 | /*----- Main checking function --------------------------------------------*/ |
521 | |
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522 | /* --- @check@ --- * |
523 | * |
524 | * Arguments: @request *rq@ = pointer to request buffer |
525 | * |
526 | * Returns: Nonzero if OK, zero if forbidden |
527 | * |
528 | * Use: Checks to see if the request is acceptable. |
529 | */ |
530 | |
531 | int check(request *rq) |
532 | { |
533 | FILE *fp; |
534 | |
535 | /* --- Check if we need to talk to a server --- */ |
536 | |
318c0b91 |
537 | #ifndef NONETWORK |
03f996bd |
538 | if ((fp = fopen(file_SERVER, "r")) != 0) |
539 | return (check__client(rq, fp)); |
318c0b91 |
540 | #endif |
c4f2d992 |
541 | |
03f996bd |
542 | /* --- Otherwise do this all the old-fashioned way --- */ |
c4f2d992 |
543 | |
544 | if ((fp = fopen(file_RULES, "r")) == 0) { |
545 | die("couldn't read configuration file `%s': %s", |
546 | file_RULES, strerror(errno)); |
547 | } |
548 | |
03f996bd |
549 | userdb_init(); |
550 | userdb_local(); |
551 | userdb_yp(); |
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552 | netg_init(); |
c4f2d992 |
553 | name_init(); |
554 | rule_init(); |
555 | lexer_scan(fp); |
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556 | parse(); |
c4f2d992 |
557 | |
558 | return (rule_check(rq)); |
559 | } |
560 | |
561 | /*----- That's all, folks -------------------------------------------------*/ |