bf3e4777df9d770994249c0144682c992546e2f6
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 /*----- Header files ------------------------------------------------------*/
49 #include <mLib/bres.h>
50 #include <mLib/dstr.h>
51 #include <mLib/mdwopt.h>
52 #include <mLib/quis.h>
53 #include <mLib/report.h>
69 /*----- Global variables --------------------------------------------------*/
71 sel_state
*sel
; /* Multiplexor for nonblocking I/O */
73 /*----- Static variables --------------------------------------------------*/
75 typedef struct conffile
{
76 struct conffile
*next
;
80 static unsigned flags
= 0; /* Global state flags */
81 static unsigned active
= 0; /* Number of active things */
82 static conffile
*conffiles
= 0; /* List of configuration files */
88 /*----- Configuration parsing ---------------------------------------------*/
92 * Arguments: @scanner *sc@ = pointer to scanner definition
96 * Use: Parses a configuration file from the scanner.
99 static source_ops
*sources
[] =
100 { &xsource_ops
, &fsource_ops
, &ssource_ops
, 0 };
101 static target_ops
*targets
[] =
102 { &xtarget_ops
, &ftarget_ops
, &starget_ops
, 0 };
104 void parse(scanner
*sc
)
109 if (sc
->t
== CTOK_EOF
)
111 if (sc
->t
!= CTOK_WORD
)
112 error(sc
, "parse error, keyword expected");
114 /* --- Handle a forwarding request --- */
116 if (strcmp(sc
->d
.buf
, "forward") == 0 ||
117 strcmp(sc
->d
.buf
, "fw") == 0 ||
118 strcmp(sc
->d
.buf
, "from") == 0) {
124 /* --- Read a source description --- */
129 /* --- Try to find a source type which understands --- */
132 for (sops
= sources
; *sops
; sops
++) {
133 if ((s
= (*sops
)->read(sc
)) != 0)
136 error(sc
, "unknown source name `%s'", sc
->d
.buf
);
138 /* --- Read any source-specific options --- */
143 while (sc
->t
== CTOK_WORD
) {
144 if (!s
->ops
->option
|| !s
->ops
->option(s
, sc
)) {
145 error(sc
, "unknown %s source option `%s'",
146 s
->ops
->name
, sc
->d
.buf
);
152 error(sc
, "parse error, missing `}'");
157 /* --- Read a destination description --- */
159 if (sc
->t
== CTOK_WORD
&& (strcmp(sc
->d
.buf
, "to") == 0 ||
160 strcmp(sc
->d
.buf
, "->") == 0))
166 /* --- Try to find a target which understands --- */
169 for (tops
= targets
; *tops
; tops
++) {
170 if ((t
= (*tops
)->read(sc
)) != 0)
173 error(sc
, "unknown target name `%s'", sc
->d
.buf
);
175 /* --- Read any target-specific options --- */
180 while (sc
->t
== CTOK_WORD
) {
181 if (!t
->ops
->option
|| !t
->ops
->option(t
, sc
)) {
182 error(sc
, "unknown %s target option `%s'",
183 t
->ops
->name
, sc
->d
.buf
);
189 error(sc
, "parse error, `}' expected");
194 /* --- Combine the source and target --- */
196 s
->ops
->attach(s
, sc
, t
);
201 /* --- Include configuration from a file --- *
203 * Slightly tricky. Scan the optional semicolon from the including
204 * stream, not the included one.
207 else if (strcmp(sc
->d
.buf
, "include") == 0) {
212 conf_name(sc
, '/', &d
);
213 if ((fp
= fopen(d
.buf
, "r")) == 0)
214 error(sc
, "can't include `%s': %s", d
.buf
, strerror(errno
));
218 scan_push(sc
, scan_file(fp
, d
.buf
, 0));
221 continue; /* Don't parse a trailing `;' */
224 /* --- Other configuration is handled elsewhere --- */
228 /* --- First try among the sources --- */
233 for (sops
= sources
; *sops
; sops
++) {
234 if ((*sops
)->option
&& (*sops
)->option(0, sc
))
239 /* --- Then try among the targets --- */
244 for (tops
= targets
; *tops
; tops
++) {
245 if ((*tops
)->option
&& (*tops
)->option(0, sc
))
250 /* --- Nobody wants the option --- */
252 error(sc
, "unknown global option or prefix `%s'", sc
->d
.buf
);
262 /*----- General utility functions -----------------------------------------*/
264 /* --- @fw_log@ --- *
266 * Arguments: @time_t t@ = when the connection occurred or (@-1@)
267 * @const char *fmt@ = format string to fill in
268 * @...@ = other arguments
272 * Use: Logs a connection.
275 void fw_log(time_t t
, const char *fmt
, ...)
281 if (flags
& FW_QUIET
)
288 d
.len
+= strftime(d
.buf
, d
.sz
, "%Y-%m-%d %H:%M:%S ", tm
);
290 dstr_vputf(&d
, fmt
, &ap
);
292 if (flags
& FW_SYSLOG
)
293 syslog(LOG_NOTICE
, "%s", d
.buf
);
296 dstr_write(&d
, stderr
);
301 /* --- @fw_inc@, @fw_dec@ --- *
307 * Use: Increments or decrements the active thing count. `fw' won't
308 * quit while there are active things.
311 void fw_inc(void) { flags
|= FW_SET
; active
++; }
312 void fw_dec(void) { if (active
) active
--; }
314 /* --- @fw_exit@ --- *
320 * Use: Exits when appropriate.
323 static void fw_exit(void)
329 /* --- @fw_tidy@ --- *
331 * Arguments: @int n@ = signal number
332 * @void *p@ = an uninteresting argument
336 * Use: Handles various signals and causes a clean tidy-up.
339 static void fw_tidy(int n
, void *p
)
343 case SIGTERM
: sn
= "SIGTERM"; break;
344 case SIGINT
: sn
= "SIGINT"; break;
348 fw_log(-1, "closing down gracefully on %s", sn
);
352 /* --- @fw_die@ --- *
354 * Arguments: @int n@ = signal number
355 * @void *p@ = an uninteresting argument
359 * Use: Handles various signals and causes an abrupt shutdown.
362 static void fw_die(int n
, void *p
)
366 case SIGQUIT
: sn
= "SIGQUIT"; break;
370 fw_log(-1, "closing down abruptly on %s", sn
);
375 /* --- @fw_reload@ --- *
377 * Arguments: @int n@ = a signal number
378 * @void *p@ = an uninteresting argument
382 * Use: Handles a hangup signal by re-reading configuration files.
385 static void fw_reload(int n
, void *p
)
393 fw_log(-1, "no configuration files to reload: ignoring SIGHUP");
396 fw_log(-1, "reloading configuration files...");
399 for (cf
= conffiles
; cf
; cf
= cf
->next
) {
400 if ((fp
= fopen(cf
->name
, "r")) == 0)
401 fw_log(-1, "error loading `%s': %s", cf
->name
, strerror(errno
));
403 scan_add(&sc
, scan_file(fp
, cf
->name
, 0));
406 fw_log(-1, "... reload completed OK");
409 /*----- Startup and options parsing ---------------------------------------*/
411 /* --- Standard GNU help options --- */
413 static void version(FILE *fp
)
415 pquis(fp
, "$ version " VERSION
"\n");
418 static void usage(FILE *fp
)
420 pquis(fp
, "Usage: $ [-dql] [-f file] [config statements...]\n");
423 static void help(FILE *fp
)
429 An excessively full-featured port-forwarder, which subsumes large chunks\n\
430 of the functionality of inetd, netcat, and normal cat. Options available\n\
433 -h, --help Display this help message.\n\
434 -v, --version Display the program's version number.\n\
435 -u, --usage Display a terse usage summary.\n\
437 -G, --grammar Show a summary of the configuration language.\n\
438 -O, --options Show a summary of the source and target options.\n\
440 -f, --file=FILE Read configuration from a file.\n\
441 -q, --quiet Don't emit any logging information.\n\
442 -d, --daemon Fork into background after initializing.\n\
443 -l, --syslog Send log output to the system logger.\n\
444 -s, --setuid=USER Change uid to USER after initializing sources.\n\
445 -g, --setgid=GRP Change gid to GRP after initializing sources.\n\
447 Configuration may be supplied in one or more configuration files, or on\n\
448 the command line (or both). If no `-f' option is present, and no\n\
449 configuration is given on the command line, the standard input stream is\n\
452 Configuration is free-form. Comments begin with a `#' character and\n\
453 continue to the end of the line. Each command line argument is considered\n\
454 to be a separate line.\n\
456 The grammar is fairly complicated. For a summary, run `$ --grammar'.\n\
457 For a summary of the various options, run `$ --options'.\n\
461 /* --- Other helpful options --- */
463 static void grammar(FILE *fp
)
470 FILE ::= EMPTY | FILE STMT [`;']\n\
471 STMT ::= OPTION-STMT | FW-STMT\n\
472 FW-STMT ::= `fw' SOURCE OPTIONS [`to'|`->'] TARGET OPTIONS\n\
473 OPTIONS ::= `{' OPTION-SEQ `}'\n\
474 OPTION-SEQ ::= EMPTY | OPTION-STMT [`;'] OPTION-SEQ\n\
477 OPTION-STMT ::= Q-OPTION\n\
478 Q-OPTION ::= OPTION\n\
479 | PREFIX `.' Q-OPTION\n\
480 | PREFIX `{' OPTION-SEQ `}'\n\
483 File source and target\n\
486 FILE ::= `file' [`.'] FSPEC [`,' FSPEC]\n\
487 FSPEC ::= FD-SPEC | NAME-SPEC | NULL-SPEC\n\
488 FD-SPEC ::= [[`:']`fd'[`:']] NUMBER|`stdin'|`stdout'\n\
489 NAME-SPEC ::= [[`:']`name'[`:']] FILE-NAME\n\
490 FILE-NAME ::= PATH-SEQ | [ PATH-SEQ ]\n\
491 PATH-SEQ ::= PATH-ELT | PATH-SEQ PATH-ELT\n\
492 PATH-ELT ::= `/' | WORD\n\
493 NULL-SPEC ::= [`:']`null'[`:']\n\
495 Exec source and target\n\
498 EXEC ::= `exec' [`.'] CMD-SPEC\n\
499 CMD-SPEC ::= SHELL-CMD | [PROG-NAME] `[' ARGV0 ARG-SEQ `]'\n\
500 ARG-SEQ ::= WORD | ARG-SEQ WORD\n\
501 SHELL-CMD ::= WORD\n\
504 Socket source and target\n\
505 SOURCE ::= SOCKET-SOURCE\n\
506 TARGET ::= SOCKET-TARGET\n\
507 SOCKET-SOURCE ::= [`socket'[`.']] [[`:']ADDR-TYPE[`:']] SOURCE-ADDR\n\
508 SOCKET-TARGET ::= [`socket'[`.']] [[`:']ADDR-TYPE[`:']] TARGET-ADDR\n\
510 INET-SOURCE-ADDR ::= [`port'] PORT\n\
511 INET-TARGET-ADDR ::= ADDRESS [`:'] PORT\n\
512 ADDRESS ::= ADDR-ELT | ADDRESS ADDR-ELT\n\
513 ADDR-ELT ::= `.' | WORD\n\
515 UNIX-SOURCE-ADDR ::= FILE-NAME\n\
516 UNIX-TARGET-ADDR ::= FILE-NAME\n\
520 static void options(FILE *fp
)
526 File attributes (`fattr')\n\
527 prefix.FATTR.MODE [=] MODE\n\
528 prefix.FATTR.OWNER [=] USER\n\
529 prefix.FATTR.GROUP [=] GROUP\n\
532 file.create [=] yes|no\n\
533 file.open [=] no|truncate|append\n\
537 exec.logging [=] yes|no\n\
538 exec.dir [=] FILE-NAME\n\
539 exec.root [=] FILE-NAME\n\
540 exec.user [=] USER\n\
541 exec.group [=] GROUP\n\
542 exec.rlimit.LIMIT[.hard|.soft] [=] VALUE\n\
544 exec.env.unset VAR\n\
545 exec.env.[set] VAR [=] VALUE\n\
548 socket.conn [=] NUMBER|unlimited|one-shot\n\
549 socket.listen [=] NUMBER\n\
550 socket.logging [=] yes|no\n\
552 socket.inet.source.[allow|deny] [host] ADDR [/ ADDR]\n\
553 socket.inet.source.[allow|deny] priv-port\n\
554 socket.inet.source.addr [=] any|ADDR\n\
555 socket.inet.dest.addr [=] any|ADDR\n\
556 socket.inet.dest.priv-port [=] yes|no\n\
558 socket.unix.fattr.*\n\
564 * Arguments: @int argc@ = number of command line arguments
565 * @char *argv[]@ = vector of argument strings
569 * Use: Simple port-forwarding server.
572 int main(int argc
, char *argv
[])
576 sig s_term
, s_quit
, s_int
, s_hup
;
580 conffile
*cf
, **cff
= &conffiles
;
587 /* --- Initialize things --- */
597 fattr_init(&fattr_global
);
602 /* --- Parse command line options --- */
605 static struct option opts
[] = {
607 /* --- Standard GNU help options --- */
609 { "help", 0, 0, 'h' },
610 { "version", 0, 0, 'v' },
611 { "usage", 0, 0, 'u' },
613 /* --- Other help options --- */
615 { "grammar", 0, 0, 'G' },
616 { "options", 0, 0, 'O' },
618 /* --- Other useful arguments --- */
620 { "file", OPTF_ARGREQ
, 0, 'f' },
621 { "fork", 0, 0, 'd' },
622 { "daemon", 0, 0, 'd' },
623 { "syslog", 0, 0, 'l' },
624 { "log", 0, 0, 'l' },
625 { "quiet", 0, 0, 'q' },
626 { "setuid", OPTF_ARGREQ
, 0, 's' },
627 { "uid", OPTF_ARGREQ
, 0, 's' },
628 { "setgid", OPTF_ARGREQ
, 0, 'g' },
629 { "gid", OPTF_ARGREQ
, 0, 'g' },
631 /* --- Magic terminator --- */
635 int i
= mdwopt(argc
, argv
, "+hvu GO f:dls:g:", opts
, 0, 0, 0);
661 if (strcmp(optarg
, "-") == 0)
662 scan_add(&sc
, scan_file(stdin
, "<stdin>", SCF_NOCLOSE
));
665 if ((fp
= fopen(optarg
, "r")) == 0)
666 die(1, "couldn't open file `%s': %s", optarg
, strerror(errno
));
667 cf
= CREATE(conffile
);
671 scan_add(&sc
, scan_file(fp
, optarg
, 0));
685 if (isdigit((unsigned char )optarg
[0])) {
687 drop
= strtol(optarg
, &q
, 0);
689 die(1, "bad uid `%s'", optarg
);
691 struct passwd
*pw
= getpwnam(optarg
);
693 die(1, "unknown user `%s'", optarg
);
698 if (isdigit((unsigned char )optarg
[0])) {
700 dropg
= strtol(optarg
, &q
, 0);
702 die(1, "bad gid `%s'", optarg
);
704 struct group
*gr
= getgrnam(optarg
);
706 die(1, "unknown group `%s'", optarg
);
722 /* --- Deal with the remaining arguments --- */
725 scan_add(&sc
, scan_argv(argv
+ optind
));
728 else if (!isatty(STDIN_FILENO
))
729 scan_add(&sc
, scan_file(stdin
, "<stdin>", SCF_NOCLOSE
));
731 moan("no configuration given and stdin is a terminal.");
732 moan("type `%s --help' for usage information.", QUIS
);
736 /* --- Parse the configuration now gathered --- */
740 /* --- Set up some signal handlers --- *
742 * Don't enable @SIGINT@ if the caller already disabled it.
748 sig_add(&s_term
, SIGTERM
, fw_tidy
, 0);
749 sig_add(&s_quit
, SIGQUIT
, fw_die
, 0);
750 sigaction(SIGINT
, 0, &sa
);
751 if (sa
.sa_handler
!= SIG_IGN
)
752 sig_add(&s_int
, SIGINT
, fw_tidy
, 0);
753 sig_add(&s_hup
, SIGHUP
, fw_reload
, 0);
756 /* --- Drop privileges --- */
758 if (drop
!= (uid_t
)-1)
760 #ifdef HAVE_SETGROUPS
761 if ((dropg
!= (gid_t
)-1 && (setgid(dropg
) || setgroups(1, &dropg
))) ||
762 (drop
!= (uid_t
)-1 && setuid(drop
)))
763 die(1, "couldn't drop privileges: %s", strerror(errno
));
765 if ((dropg
!= (gid_t
)-1 && setgid(dropg
)) ||
766 (drop
!= (uid_t
)-1 && setuid(drop
)))
767 die(1, "couldn't drop privileges: %s", strerror(errno
));
770 /* --- Fork into the background --- */
777 die(1, "couldn't fork: %s", strerror(errno
));
781 close(0); close(1); close(2);
792 openlog(QUIS
, 0, LOG_DAEMON
);
795 /* --- Let rip --- */
797 if (!(flags
& FW_SET
))
798 moan("nothing to do!");
799 signal(SIGPIPE
, SIG_IGN
);
804 if (!sel_select(sel
))
806 else if (errno
!= EINTR
&& errno
!= EAGAIN
) {
807 fw_log(-1, "error from select: %s", strerror(errno
));
810 fw_log(-1, "too many consecutive select errors: bailing out");
820 /*----- That's all, folks -------------------------------------------------*/