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1 | /* -*-c-*- |
2 | * |
1e8a64e8 |
3 | * $Id: fw.c,v 1.8 2000/03/23 23:19:19 mdw Exp $ |
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4 | * |
5 | * Port forwarding thingy |
6 | * |
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7 | * (c) 1999 Straylight/Edgeware |
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8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the `fw' port forwarder. |
13 | * |
14 | * `fw' 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 | * `fw' 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 `fw'; 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: fw.c,v $ |
1e8a64e8 |
32 | * Revision 1.8 2000/03/23 23:19:19 mdw |
33 | * Fix changed options in parser table. |
34 | * |
fc170a33 |
35 | * Revision 1.7 2000/03/23 00:37:33 mdw |
36 | * Add option to change user and group after initialization. Naughtily |
37 | * reassign short equivalents of --grammar and --options. |
38 | * |
17be1d6b |
39 | * Revision 1.6 1999/12/22 15:44:10 mdw |
40 | * Make syslog a separate option, and do it better. |
41 | * |
06d82312 |
42 | * Revision 1.5 1999/10/22 22:47:50 mdw |
43 | * Grammar changes. Also, don't enable SIGINT if it's currently ignored. |
44 | * |
2d9ec601 |
45 | * Revision 1.4 1999/10/10 16:46:12 mdw |
46 | * New resolver to initialize. Also, include options for grammar and |
47 | * options references. |
48 | * |
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49 | * Revision 1.3 1999/07/26 23:30:42 mdw |
50 | * Major reconstruction work for new design. |
51 | * |
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52 | * Revision 1.2 1999/07/03 13:55:17 mdw |
53 | * Various changes. Add configuration grammar to help text. Change to |
54 | * root directory and open syslog when forking into background. |
55 | * |
56 | * Revision 1.1.1.1 1999/07/01 08:56:23 mdw |
57 | * Initial revision. |
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58 | * |
59 | */ |
60 | |
61 | /*----- Header files ------------------------------------------------------*/ |
62 | |
63 | #include "config.h" |
64 | |
65 | #include <ctype.h> |
66 | #include <errno.h> |
61e3dbdf |
67 | #include <signal.h> |
68 | #include <stdarg.h> |
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69 | #include <stdio.h> |
70 | #include <stdlib.h> |
71 | #include <string.h> |
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72 | #include <time.h> |
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73 | |
74 | #include <unistd.h> |
75 | #include <syslog.h> |
76 | |
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77 | #include <grp.h> |
78 | #include <pwd.h> |
79 | |
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80 | #include <mLib/bres.h> |
61e3dbdf |
81 | #include <mLib/dstr.h> |
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82 | #include <mLib/mdwopt.h> |
83 | #include <mLib/quis.h> |
84 | #include <mLib/report.h> |
85 | #include <mLib/sel.h> |
61e3dbdf |
86 | #include <mLib/sig.h> |
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87 | #include <mLib/sub.h> |
88 | |
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89 | #include "conf.h" |
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90 | #include "endpt.h" |
91 | #include "exec.h" |
92 | #include "fattr.h" |
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93 | #include "fw.h" |
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94 | #include "scan.h" |
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95 | #include "source.h" |
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96 | |
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97 | /*----- Global variables --------------------------------------------------*/ |
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98 | |
99 | sel_state *sel; /* Multiplexor for nonblocking I/O */ |
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100 | |
101 | /*----- Static variables --------------------------------------------------*/ |
102 | |
103 | static unsigned flags = 0; /* Global state flags */ |
104 | static unsigned active = 0; /* Number of active things */ |
105 | |
106 | #define FW_SYSLOG 1u |
107 | #define FW_QUIET 2u |
108 | #define FW_SET 4u |
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109 | |
110 | /*----- Main code ---------------------------------------------------------*/ |
111 | |
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112 | /* --- @fw_log@ --- * |
113 | * |
114 | * Arguments: @time_t t@ = when the connection occurred or (@-1@) |
115 | * @const char *fmt@ = format string to fill in |
116 | * @...@ = other arguments |
117 | * |
118 | * Returns: --- |
119 | * |
120 | * Use: Logs a connection. |
121 | */ |
122 | |
123 | void fw_log(time_t t, const char *fmt, ...) |
124 | { |
125 | struct tm *tm; |
126 | dstr d = DSTR_INIT; |
127 | va_list ap; |
128 | |
129 | if (flags & FW_QUIET) |
130 | return; |
131 | |
132 | if (t == -1) |
133 | t = time(0); |
134 | tm = localtime(&t); |
135 | DENSURE(&d, 64); |
17be1d6b |
136 | d.len += strftime(d.buf, d.sz, "%Y-%m-%d %H:%M:%S ", tm); |
61e3dbdf |
137 | va_start(ap, fmt); |
138 | dstr_vputf(&d, fmt, ap); |
139 | va_end(ap); |
140 | if (flags & FW_SYSLOG) |
141 | syslog(LOG_NOTICE, "%s", d.buf); |
142 | else { |
143 | DPUTC(&d, '\n'); |
144 | dstr_write(&d, stderr); |
145 | } |
146 | DDESTROY(&d); |
147 | } |
148 | |
149 | /* --- @fw_inc@, @fw_dec@ --- * |
150 | * |
151 | * Arguments: --- |
152 | * |
153 | * Returns: --- |
154 | * |
155 | * Use: Increments or decrements the active thing count. `fw' won't |
156 | * quit while there are active things. |
157 | */ |
158 | |
159 | void fw_inc(void) { flags |= FW_SET; active++; } |
160 | void fw_dec(void) { if (active) active--; } |
161 | |
162 | /* --- @fw_exit@ --- * |
163 | * |
164 | * Arguments: --- |
165 | * |
166 | * Returns: --- |
167 | * |
168 | * Use: Exits when appropriate. |
169 | */ |
170 | |
171 | static void fw_exit(void) |
172 | { |
173 | endpt_killall(); |
174 | source_killall(); |
175 | } |
176 | |
177 | /* --- @fw_tidy@ --- * |
178 | * |
179 | * Arguments: @int n@ = signal number |
180 | * @void *p@ = an uninteresting argument |
181 | * |
182 | * Returns: --- |
183 | * |
184 | * Use: Handles various signals and causes a clean tidy-up. |
185 | */ |
186 | |
187 | static void fw_tidy(int n, void *p) |
188 | { |
189 | const char *sn = "unexpected signal (bug!)"; |
190 | if (n == SIGTERM) |
191 | sn = "SIGTERM"; |
192 | else if (n == SIGINT) |
193 | sn = "SIGINT"; |
194 | |
195 | fw_log(-1, "closing down on %s", sn); |
196 | fw_exit(); |
197 | } |
198 | |
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199 | /* --- Standard GNU help options --- */ |
200 | |
201 | static void version(FILE *fp) |
202 | { |
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203 | pquis(fp, "$ version " VERSION "\n"); |
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204 | } |
205 | |
206 | static void usage(FILE *fp) |
207 | { |
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208 | pquis(fp, "Usage: $ [-dql] [-f file] [config statements...]\n"); |
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209 | } |
210 | |
211 | static void help(FILE *fp) |
212 | { |
213 | version(fp); |
214 | fputc('\n', fp); |
215 | usage(fp); |
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216 | pquis(fp, "\n\ |
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217 | An excessively full-featured port-forwarder, which subsumes large chunks\n\ |
218 | of the functionality of inetd, netcat, and normal cat. Options available\n\ |
219 | are:\n\ |
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220 | \n\ |
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221 | -h, --help Display this help message.\n\ |
222 | -v, --version Display the program's version number.\n\ |
223 | -u, --usage Display a terse usage summary.\n\ |
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224 | \n\ |
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225 | -G, --grammar Show a summary of the configuration language.\n\ |
226 | -O, --options Show a summary of the source and target options.\n\ |
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227 | \n\ |
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228 | -f, --file=FILE Read configuration from a file.\n\ |
229 | -q, --quiet Don't emit any logging information.\n\ |
230 | -d, --daemon Fork into background after initializing.\n\ |
231 | -l, --syslog Send log output to the system logger.\n\ |
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232 | -s, --setuid=USER Change uid to USER after initializing sources.\n\ |
233 | -g, --setgid=GRP Change gid to GRP after initializing sources.\n\ |
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234 | \n\ |
235 | Configuration may be supplied in one or more configuration files, or on\n\ |
236 | the command line (or both). If no `-f' option is present, and no\n\ |
237 | configuration is given on the command line, the standard input stream is\n\ |
238 | read.\n\ |
239 | \n\ |
240 | Configuration is free-form. Comments begin with a `#' character and\n\ |
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241 | continue to the end of the line. Each command line argument is considered\n\ |
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242 | to be a separate line.\n\ |
afd7451e |
243 | \n\ |
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244 | The grammar is fairly complicated. For a summary, run `$ --grammar'.\n\ |
245 | For a summary of the various options, run `$ --options'.\n\ |
246 | "); |
247 | } |
248 | |
249 | /* --- Other helpful options --- */ |
250 | |
251 | static void grammar(FILE *fp) |
252 | { |
253 | version(fp); |
254 | pquis(fp, "\n\ |
255 | Grammar summary\n\ |
256 | \n\ |
257 | Basic syntax\n\ |
258 | file ::= empty | file stmt [`;']\n\ |
259 | stmt ::= option-stmt | fw-stmt\n\ |
260 | fw-stmt ::= `fw' source options [`to'|`->'] target options\n\ |
261 | options ::= `{' option-seq `}'\n\ |
262 | option-seq ::= empty | option-stmt [`;'] option-seq\n\ |
263 | \n\ |
264 | Option syntax\n\ |
265 | option-stmt ::= q-option\n\ |
266 | q-option ::= option\n\ |
267 | | prefix `.' q-option\n\ |
268 | | prefix `{' option-seq `}'\n\ |
269 | prefix ::= word\n\ |
270 | \n\ |
271 | File source and target\n\ |
272 | source ::= file\n\ |
273 | target ::= file\n\ |
274 | file ::= `file' [`.'] fspec [`,' fspec]\n\ |
275 | fspec ::= fd-spec | name-spec | null-spec\n\ |
276 | fd-spec ::= [[`:']`fd'[`:']] number|`stdin'|`stdout'\n\ |
277 | name-spec ::= [[`:']`file'[`:']] file-name\n\ |
278 | file-name ::= path-seq | [ path-seq ]\n\ |
279 | path-seq ::= path-elt | path-seq path-elt\n\ |
280 | path-elt ::= `/' | word\n\ |
281 | null-spec ::= [`:']`null'[`:']\n\ |
282 | \n\ |
283 | Exec source and target\n\ |
284 | source ::= exec\n\ |
285 | target ::= exec\n\ |
286 | exec ::= `exec' [`.'] cmd-spec\n\ |
287 | cmd-spec ::= shell-cmd | [prog-name] `[' argv0 arg-seq `]'\n\ |
288 | arg-seq ::= word | arg-seq word\n\ |
289 | shell-cmd ::= word\n\ |
290 | argv0 ::= word\n\ |
291 | \n\ |
292 | Socket source and target\n\ |
293 | source ::= socket-source\n\ |
294 | target ::= socket-target\n\ |
295 | socket-source ::= [`socket'[`.']] [[`:']addr-type[`:']] source-addr\n\ |
296 | socket-target ::= [`socket'[`.']] [[`:']addr-type[`:']] target-addr\n\ |
297 | \n\ |
298 | inet-source-addr ::= [port] port\n\ |
299 | inet-target-addr ::= address [`:'] port\n\ |
300 | address ::= addr-elt | address addr-elt\n\ |
301 | addr-elt ::= `.' | word\n\ |
302 | \n\ |
303 | unix-source-addr ::= file-name\n\ |
304 | unix-target-addr ::= file-name\n\ |
305 | "); |
306 | } |
307 | |
308 | static void options(FILE *fp) |
309 | { |
310 | version(fp); |
311 | pquis(fp, "\n\ |
312 | Options summary\n\ |
313 | \n\ |
314 | File attributes (`fattr')\n\ |
315 | prefix.fattr.mode [=] mode\n\ |
316 | prefix.fattr.owner [=] user\n\ |
317 | prefix.fattr.group [=] group\n\ |
318 | \n\ |
319 | File options\n\ |
320 | file.create [=] yes|no\n\ |
321 | file.open [=] no|truncate|append\n\ |
322 | file.fattr.*\n\ |
323 | \n\ |
324 | Exec options\n\ |
325 | exec.logging [=] yes|no\n\ |
326 | exec.dir [=] file-name\n\ |
327 | exec.root [=] file-name\n\ |
328 | exec.user [=] user\n\ |
329 | exec.group [=] group\n\ |
330 | exec.rlimit.limit[.hard|.soft] [=] value\n\ |
331 | exec.env.clear\n\ |
332 | exec.env.unset var\n\ |
333 | exec.env.[set] var [=] value\n\ |
334 | \n\ |
335 | Socket options\n\ |
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336 | socket.conn [=] number|unlimited|one-shot\n\ |
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337 | socket.logging [=] yes|no\n\ |
338 | socket.inet.[allow|deny] [from] address [/ address]\n\ |
339 | socket.unix.fattr.*\n\ |
340 | "); |
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341 | } |
342 | |
343 | /* --- @main@ --- * |
344 | * |
345 | * Arguments: @int argc@ = number of command line arguments |
346 | * @char *argv[]@ = vector of argument strings |
347 | * |
348 | * Returns: --- |
349 | * |
350 | * Use: Simple port-forwarding server. |
351 | */ |
352 | |
353 | int main(int argc, char *argv[]) |
354 | { |
355 | unsigned f = 0; |
356 | sel_state sst; |
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357 | sig s_term, s_int; |
358 | scanner sc; |
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359 | uid_t drop = -1; |
360 | gid_t dropg = -1; |
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361 | |
362 | enum { |
363 | f_bogus = 1, |
364 | f_file = 2, |
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365 | f_syslog = 4, |
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366 | f_fork = 8 |
367 | }; |
368 | |
369 | /* --- Initialize things --- */ |
370 | |
371 | ego(argv[0]); |
372 | sel = &sst; |
373 | sel_init(sel); |
374 | sub_init(); |
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375 | sig_init(sel); |
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376 | bres_init(sel); |
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377 | bres_exec(0); |
61e3dbdf |
378 | exec_init(); |
379 | fattr_init(&fattr_global); |
380 | scan_create(&sc); |
381 | |
06d82312 |
382 | /* --- Set up some signal handlers --- * |
383 | * |
384 | * Don't enable @SIGINT@ if the caller already disabled it. |
385 | */ |
386 | |
387 | { |
388 | struct sigaction sa; |
389 | |
390 | sig_add(&s_term, SIGTERM, fw_tidy, 0); |
391 | sigaction(SIGINT, 0, &sa); |
392 | if (sa.sa_handler != SIG_IGN) |
393 | sig_add(&s_int, SIGINT, fw_tidy, 0); |
394 | } |
61e3dbdf |
395 | |
61e3dbdf |
396 | atexit(fw_exit); |
e82f7154 |
397 | |
398 | /* --- Parse command line options --- */ |
399 | |
400 | for (;;) { |
401 | static struct option opts[] = { |
402 | |
403 | /* --- Standard GNU help options --- */ |
404 | |
405 | { "help", 0, 0, 'h' }, |
406 | { "version", 0, 0, 'v' }, |
407 | { "usage", 0, 0, 'u' }, |
408 | |
2d9ec601 |
409 | /* --- Other help options --- */ |
410 | |
1e8a64e8 |
411 | { "grammar", 0, 0, 'G' }, |
412 | { "options", 0, 0, 'O' }, |
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413 | |
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414 | /* --- Other useful arguments --- */ |
415 | |
416 | { "file", OPTF_ARGREQ, 0, 'f' }, |
61e3dbdf |
417 | { "fork", 0, 0, 'd' }, |
418 | { "daemon", 0, 0, 'd' }, |
17be1d6b |
419 | { "syslog", 0, 0, 'l' }, |
420 | { "log", 0, 0, 'l' }, |
61e3dbdf |
421 | { "quiet", 0, 0, 'q' }, |
fc170a33 |
422 | { "setuid", OPTF_ARGREQ, 0, 's' }, |
423 | { "uid", OPTF_ARGREQ, 0, 's' }, |
424 | { "setgid", OPTF_ARGREQ, 0, 'g' }, |
425 | { "gid", OPTF_ARGREQ, 0, 'g' }, |
e82f7154 |
426 | |
427 | /* --- Magic terminator --- */ |
428 | |
429 | { 0, 0, 0, 0 } |
430 | }; |
fc170a33 |
431 | int i = mdwopt(argc, argv, "+hvu GO f:dls:g:", opts, 0, 0, 0); |
e82f7154 |
432 | |
433 | if (i < 0) |
434 | break; |
435 | switch (i) { |
436 | case 'h': |
437 | help(stdout); |
438 | exit(0); |
439 | break; |
440 | case 'v': |
441 | version(stdout); |
442 | exit(0); |
443 | break; |
444 | case 'u': |
445 | usage(stdout); |
446 | exit(0); |
447 | break; |
fc170a33 |
448 | case 'G': |
2d9ec601 |
449 | grammar(stdout); |
450 | exit(0); |
451 | break; |
fc170a33 |
452 | case 'O': |
2d9ec601 |
453 | options(stdout); |
454 | exit(0); |
455 | break; |
61e3dbdf |
456 | case 'f': |
457 | if (strcmp(optarg, "-") == 0) |
458 | scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE)); |
459 | else { |
460 | FILE *fp; |
461 | if ((fp = fopen(optarg, "r")) == 0) |
462 | die(1, "couldn't open file `%s': %s", optarg, strerror(errno)); |
463 | scan_add(&sc, scan_file(fp, optarg, 0)); |
464 | } |
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465 | f |= f_file; |
e82f7154 |
466 | break; |
61e3dbdf |
467 | case 'd': |
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468 | f |= f_fork; |
469 | break; |
17be1d6b |
470 | case 'l': |
471 | f |= f_syslog; |
472 | break; |
61e3dbdf |
473 | case 'q': |
474 | flags |= FW_QUIET; |
475 | break; |
fc170a33 |
476 | case 's': |
477 | if (isdigit((unsigned char )optarg[0])) { |
478 | char *q; |
479 | drop = strtol(optarg, &q, 0); |
480 | if (*q) |
481 | die(1, "bad uid `%s'", optarg); |
482 | } else { |
483 | struct passwd *pw = getpwnam(optarg); |
484 | if (!pw) |
485 | die(1, "unknown user `%s'", optarg); |
486 | drop = pw->pw_uid; |
487 | } |
488 | break; |
489 | case 'g': |
490 | if (isdigit((unsigned char )optarg[0])) { |
491 | char *q; |
492 | dropg = strtol(optarg, &q, 0); |
493 | if (*q) |
494 | die(1, "bad gid `%s'", optarg); |
495 | } else { |
496 | struct group *gr = getgrnam(optarg); |
497 | if (!gr) |
498 | die(1, "unknown group `%s'", optarg); |
499 | dropg = gr->gr_gid; |
500 | } |
501 | break; |
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502 | default: |
503 | f |= f_bogus; |
504 | break; |
505 | } |
506 | } |
507 | |
508 | if (f & f_bogus) { |
509 | usage(stderr); |
510 | exit(1); |
511 | } |
512 | |
513 | /* --- Deal with the remaining arguments --- */ |
514 | |
61e3dbdf |
515 | if (optind < argc) |
516 | scan_add(&sc, scan_argv(argv + optind)); |
517 | else if (f & f_file) |
518 | /* Cool */; |
519 | else if (!isatty(STDIN_FILENO)) |
520 | scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE)); |
521 | else { |
522 | moan("no configuration given and stdin is a terminal."); |
523 | moan("type `%s --help' for usage information.", QUIS); |
524 | exit(1); |
e82f7154 |
525 | } |
526 | |
61e3dbdf |
527 | /* --- Parse the configuration now gathered --- */ |
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528 | |
61e3dbdf |
529 | conf_parse(&sc); |
e82f7154 |
530 | |
fc170a33 |
531 | /* --- Drop privileges --- */ |
532 | |
533 | #ifdef HAVE_SETGROUPS |
534 | if ((dropg != -1 && (setgid(dropg) || setgroups(1, &dropg))) || |
535 | #else |
536 | if ((dropg != -1 && setgid(dropg)) || |
537 | #endif |
538 | (drop != -1 && setuid(drop))) |
539 | die(1, "couldn't drop privileges: %s", strerror(errno)); |
540 | |
e82f7154 |
541 | /* --- Fork into the background --- */ |
542 | |
543 | if (f & f_fork) { |
544 | pid_t kid; |
545 | |
546 | kid = fork(); |
547 | if (kid == -1) |
548 | die(1, "couldn't fork: %s", strerror(errno)); |
549 | if (kid != 0) |
550 | _exit(0); |
551 | |
552 | close(0); close(1); close(2); |
afd7451e |
553 | chdir("/"); |
e82f7154 |
554 | setsid(); |
555 | |
556 | kid = fork(); |
557 | if (kid != 0) |
558 | _exit(0); |
17be1d6b |
559 | } |
afd7451e |
560 | |
17be1d6b |
561 | if (f & f_syslog) { |
afd7451e |
562 | flags |= FW_SYSLOG; |
563 | openlog(QUIS, 0, LOG_DAEMON); |
e82f7154 |
564 | } |
565 | |
566 | /* --- Let rip --- */ |
567 | |
61e3dbdf |
568 | if (!(flags & FW_SET)) |
569 | moan("nothing to do!"); |
570 | signal(SIGPIPE, SIG_IGN); |
571 | while (active) |
e82f7154 |
572 | sel_select(sel); |
573 | return (0); |
574 | } |
575 | |
576 | /*----- That's all, folks -------------------------------------------------*/ |