3 * $Id: fw.c,v 1.11 2001/02/03 20:33:26 mdw Exp $
5 * Port forwarding thingy
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the `fw' port forwarder.
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.
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.
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.
29 /*----- Revision history --------------------------------------------------*
32 * Revision 1.11 2001/02/03 20:33:26 mdw
33 * Fix flags to be unsigned.
35 * Revision 1.10 2001/02/03 20:30:03 mdw
36 * Support re-reading config files on SIGHUP.
38 * Revision 1.9 2001/01/20 11:55:17 mdw
39 * Handle select errors more robustly.
41 * Revision 1.8 2000/03/23 23:19:19 mdw
42 * Fix changed options in parser table.
44 * Revision 1.7 2000/03/23 00:37:33 mdw
45 * Add option to change user and group after initialization. Naughtily
46 * reassign short equivalents of --grammar and --options.
48 * Revision 1.6 1999/12/22 15:44:10 mdw
49 * Make syslog a separate option, and do it better.
51 * Revision 1.5 1999/10/22 22:47:50 mdw
52 * Grammar changes. Also, don't enable SIGINT if it's currently ignored.
54 * Revision 1.4 1999/10/10 16:46:12 mdw
55 * New resolver to initialize. Also, include options for grammar and
58 * Revision 1.3 1999/07/26 23:30:42 mdw
59 * Major reconstruction work for new design.
61 * Revision 1.2 1999/07/03 13:55:17 mdw
62 * Various changes. Add configuration grammar to help text. Change to
63 * root directory and open syslog when forking into background.
65 * Revision 1.1.1.1 1999/07/01 08:56:23 mdw
70 /*----- Header files ------------------------------------------------------*/
90 #include <mLib/bres.h>
91 #include <mLib/dstr.h>
92 #include <mLib/mdwopt.h>
93 #include <mLib/quis.h>
94 #include <mLib/report.h>
107 /*----- Global variables --------------------------------------------------*/
109 sel_state *sel; /* Multiplexor for nonblocking I/O */
111 /*----- Static variables --------------------------------------------------*/
113 typedef struct conffile {
114 struct conffile *next;
118 static unsigned flags = 0; /* Global state flags */
119 static unsigned active = 0; /* Number of active things */
120 static conffile *conffiles = 0; /* List of configuration files */
126 /*----- Main code ---------------------------------------------------------*/
128 /* --- @fw_log@ --- *
130 * Arguments: @time_t t@ = when the connection occurred or (@-1@)
131 * @const char *fmt@ = format string to fill in
132 * @...@ = other arguments
136 * Use: Logs a connection.
139 void fw_log(time_t t, const char *fmt, ...)
145 if (flags & FW_QUIET)
152 d.len += strftime(d.buf, d.sz, "%Y-%m-%d %H:%M:%S ", tm);
154 dstr_vputf(&d, fmt, ap);
156 if (flags & FW_SYSLOG)
157 syslog(LOG_NOTICE, "%s", d.buf);
160 dstr_write(&d, stderr);
165 /* --- @fw_inc@, @fw_dec@ --- *
171 * Use: Increments or decrements the active thing count. `fw' won't
172 * quit while there are active things.
175 void fw_inc(void) { flags |= FW_SET; active++; }
176 void fw_dec(void) { if (active) active--; }
178 /* --- @fw_exit@ --- *
184 * Use: Exits when appropriate.
187 static void fw_exit(void)
193 /* --- @fw_tidy@ --- *
195 * Arguments: @int n@ = signal number
196 * @void *p@ = an uninteresting argument
200 * Use: Handles various signals and causes a clean tidy-up.
203 static void fw_tidy(int n, void *p)
207 case SIGTERM: sn = "SIGTERM"; break;
208 case SIGINT: sn = "SIGINT"; break;
212 fw_log(-1, "closing down gracefully on %s", sn);
216 /* --- @fw_die@ --- *
218 * Arguments: @int n@ = signal number
219 * @void *p@ = an uninteresting argument
223 * Use: Handles various signals and causes an abrupt shutdown.
226 static void fw_die(int n, void *p)
230 case SIGQUIT: sn = "SIGQUIT"; break;
234 fw_log(-1, "closing down abruptly on %s", sn);
239 /* --- @fw_reload@ --- *
241 * Arguments: @int n@ = a signal number
242 * @void *p@ = an uninteresting argument
246 * Use: Handles a hangup signal by re-reading configuration files.
249 static void fw_reload(int n, void *p)
257 fw_log(-1, "no configuration files to reload: ignoring SIGHUP");
260 fw_log(-1, "reloading configuration files...");
263 for (cf = conffiles; cf; cf = cf->next) {
264 if ((fp = fopen(cf->name, "r")) == 0)
265 fw_log(-1, "error loading `%s': %s", cf->name, strerror(errno));
267 scan_add(&sc, scan_file(fp, cf->name, 0));
270 fw_log(-1, "... reload completed OK");
273 /* --- Standard GNU help options --- */
275 static void version(FILE *fp)
277 pquis(fp, "$ version " VERSION "\n");
280 static void usage(FILE *fp)
282 pquis(fp, "Usage: $ [-dql] [-f file] [config statements...]\n");
285 static void help(FILE *fp)
291 An excessively full-featured port-forwarder, which subsumes large chunks\n\
292 of the functionality of inetd, netcat, and normal cat. Options available\n\
295 -h, --help Display this help message.\n\
296 -v, --version Display the program's version number.\n\
297 -u, --usage Display a terse usage summary.\n\
299 -G, --grammar Show a summary of the configuration language.\n\
300 -O, --options Show a summary of the source and target options.\n\
302 -f, --file=FILE Read configuration from a file.\n\
303 -q, --quiet Don't emit any logging information.\n\
304 -d, --daemon Fork into background after initializing.\n\
305 -l, --syslog Send log output to the system logger.\n\
306 -s, --setuid=USER Change uid to USER after initializing sources.\n\
307 -g, --setgid=GRP Change gid to GRP after initializing sources.\n\
309 Configuration may be supplied in one or more configuration files, or on\n\
310 the command line (or both). If no `-f' option is present, and no\n\
311 configuration is given on the command line, the standard input stream is\n\
314 Configuration is free-form. Comments begin with a `#' character and\n\
315 continue to the end of the line. Each command line argument is considered\n\
316 to be a separate line.\n\
318 The grammar is fairly complicated. For a summary, run `$ --grammar'.\n\
319 For a summary of the various options, run `$ --options'.\n\
323 /* --- Other helpful options --- */
325 static void grammar(FILE *fp)
332 file ::= empty | file stmt [`;']\n\
333 stmt ::= option-stmt | fw-stmt\n\
334 fw-stmt ::= `fw' source options [`to'|`->'] target options\n\
335 options ::= `{' option-seq `}'\n\
336 option-seq ::= empty | option-stmt [`;'] option-seq\n\
339 option-stmt ::= q-option\n\
340 q-option ::= option\n\
341 | prefix `.' q-option\n\
342 | prefix `{' option-seq `}'\n\
345 File source and target\n\
348 file ::= `file' [`.'] fspec [`,' fspec]\n\
349 fspec ::= fd-spec | name-spec | null-spec\n\
350 fd-spec ::= [[`:']`fd'[`:']] number|`stdin'|`stdout'\n\
351 name-spec ::= [[`:']`file'[`:']] file-name\n\
352 file-name ::= path-seq | [ path-seq ]\n\
353 path-seq ::= path-elt | path-seq path-elt\n\
354 path-elt ::= `/' | word\n\
355 null-spec ::= [`:']`null'[`:']\n\
357 Exec source and target\n\
360 exec ::= `exec' [`.'] cmd-spec\n\
361 cmd-spec ::= shell-cmd | [prog-name] `[' argv0 arg-seq `]'\n\
362 arg-seq ::= word | arg-seq word\n\
363 shell-cmd ::= word\n\
366 Socket source and target\n\
367 source ::= socket-source\n\
368 target ::= socket-target\n\
369 socket-source ::= [`socket'[`.']] [[`:']addr-type[`:']] source-addr\n\
370 socket-target ::= [`socket'[`.']] [[`:']addr-type[`:']] target-addr\n\
372 inet-source-addr ::= [port] port\n\
373 inet-target-addr ::= address [`:'] port\n\
374 address ::= addr-elt | address addr-elt\n\
375 addr-elt ::= `.' | word\n\
377 unix-source-addr ::= file-name\n\
378 unix-target-addr ::= file-name\n\
382 static void options(FILE *fp)
388 File attributes (`fattr')\n\
389 prefix.fattr.mode [=] mode\n\
390 prefix.fattr.owner [=] user\n\
391 prefix.fattr.group [=] group\n\
394 file.create [=] yes|no\n\
395 file.open [=] no|truncate|append\n\
399 exec.logging [=] yes|no\n\
400 exec.dir [=] file-name\n\
401 exec.root [=] file-name\n\
402 exec.user [=] user\n\
403 exec.group [=] group\n\
404 exec.rlimit.limit[.hard|.soft] [=] value\n\
406 exec.env.unset var\n\
407 exec.env.[set] var [=] value\n\
410 socket.conn [=] number|unlimited|one-shot\n\
411 socket.logging [=] yes|no\n\
412 socket.inet.[allow|deny] [from] address [/ address]\n\
413 socket.unix.fattr.*\n\
419 * Arguments: @int argc@ = number of command line arguments
420 * @char *argv[]@ = vector of argument strings
424 * Use: Simple port-forwarding server.
427 int main(int argc, char *argv[])
431 sig s_term, s_quit, s_int, s_hup;
435 conffile *cf, **cff = &conffiles;
442 /* --- Initialize things --- */
452 fattr_init(&fattr_global);
457 /* --- Parse command line options --- */
460 static struct option opts[] = {
462 /* --- Standard GNU help options --- */
464 { "help", 0, 0, 'h' },
465 { "version", 0, 0, 'v' },
466 { "usage", 0, 0, 'u' },
468 /* --- Other help options --- */
470 { "grammar", 0, 0, 'G' },
471 { "options", 0, 0, 'O' },
473 /* --- Other useful arguments --- */
475 { "file", OPTF_ARGREQ, 0, 'f' },
476 { "fork", 0, 0, 'd' },
477 { "daemon", 0, 0, 'd' },
478 { "syslog", 0, 0, 'l' },
479 { "log", 0, 0, 'l' },
480 { "quiet", 0, 0, 'q' },
481 { "setuid", OPTF_ARGREQ, 0, 's' },
482 { "uid", OPTF_ARGREQ, 0, 's' },
483 { "setgid", OPTF_ARGREQ, 0, 'g' },
484 { "gid", OPTF_ARGREQ, 0, 'g' },
486 /* --- Magic terminator --- */
490 int i = mdwopt(argc, argv, "+hvu GO f:dls:g:", opts, 0, 0, 0);
516 if (strcmp(optarg, "-") == 0)
517 scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
520 if ((fp = fopen(optarg, "r")) == 0)
521 die(1, "couldn't open file `%s': %s", optarg, strerror(errno));
522 cf = CREATE(conffile);
526 scan_add(&sc, scan_file(fp, optarg, 0));
540 if (isdigit((unsigned char )optarg[0])) {
542 drop = strtol(optarg, &q, 0);
544 die(1, "bad uid `%s'", optarg);
546 struct passwd *pw = getpwnam(optarg);
548 die(1, "unknown user `%s'", optarg);
553 if (isdigit((unsigned char )optarg[0])) {
555 dropg = strtol(optarg, &q, 0);
557 die(1, "bad gid `%s'", optarg);
559 struct group *gr = getgrnam(optarg);
561 die(1, "unknown group `%s'", optarg);
577 /* --- Deal with the remaining arguments --- */
580 scan_add(&sc, scan_argv(argv + optind));
583 else if (!isatty(STDIN_FILENO))
584 scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
586 moan("no configuration given and stdin is a terminal.");
587 moan("type `%s --help' for usage information.", QUIS);
591 /* --- Parse the configuration now gathered --- */
595 /* --- Set up some signal handlers --- *
597 * Don't enable @SIGINT@ if the caller already disabled it.
603 sig_add(&s_term, SIGTERM, fw_tidy, 0);
604 sig_add(&s_quit, SIGQUIT, fw_die, 0);
605 sigaction(SIGINT, 0, &sa);
606 if (sa.sa_handler != SIG_IGN)
607 sig_add(&s_int, SIGINT, fw_tidy, 0);
608 sig_add(&s_hup, SIGHUP, fw_reload, 0);
611 /* --- Drop privileges --- */
613 #ifdef HAVE_SETGROUPS
614 if ((dropg != -1 && (setgid(dropg) || setgroups(1, &dropg))) ||
615 (drop != -1 && setuid(drop)))
616 die(1, "couldn't drop privileges: %s", strerror(errno));
618 if ((dropg != -1 && setgid(dropg)) ||
619 (drop != -1 && setuid(drop)))
620 die(1, "couldn't drop privileges: %s", strerror(errno));
623 /* --- Fork into the background --- */
630 die(1, "couldn't fork: %s", strerror(errno));
634 close(0); close(1); close(2);
645 openlog(QUIS, 0, LOG_DAEMON);
648 /* --- Let rip --- */
650 if (!(flags & FW_SET))
651 moan("nothing to do!");
652 signal(SIGPIPE, SIG_IGN);
657 if (!sel_select(sel))
659 else if (errno != EINTR && errno != EAGAIN) {
660 fw_log(-1, "error from select: %s", strerror(errno));
663 fw_log(-1, "too many consecutive select errors: bailing out");
673 /*----- That's all, folks -------------------------------------------------*/