xref: /f-stack/tools/ipfw/main.c (revision d4a07e70)
1 /*-
2  * Copyright (c) 2002-2003,2010 Luigi Rizzo
3  * Copyright (c) 1996 Alex Nash, Paul Traina, Poul-Henning Kamp
4  * Copyright (c) 1994 Ugen J.S.Antsilevich
5  *
6  * Idea and grammar partially left from:
7  * Copyright (c) 1993 Daniel Boulet
8  *
9  * Redistribution and use in source forms, with and without modification,
10  * are permitted provided that this entire comment appears intact.
11  *
12  * Redistribution in binary form may occur without any restrictions.
13  * Obviously, it would be nice if you gave credit where credit is due
14  * but requiring it would be too onerous.
15  *
16  * This software is provided ``AS IS'' without any warranties of any kind.
17  *
18  * Command line interface for IP firewall facility
19  *
20  * $FreeBSD$
21  */
22 
23 #include <sys/wait.h>
24 #include <ctype.h>
25 #include <err.h>
26 #include <errno.h>
27 #include <signal.h>
28 #include <stdio.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include <sysexits.h>
32 #include <unistd.h>
33 
34 #ifdef FSTACK
35 #include <stdint.h>
36 #include "compat.h"
37 
38 #include "ff_ipc.h"
39 #endif
40 
41 #include "ipfw2.h"
42 
43 static void
help(void)44 help(void)
45 {
46 	fprintf(stderr,
47 "ipfw syntax summary (but please do read the ipfw(8) manpage):\n\n"
48 #ifndef FSTACK
49 "\tipfw [-abcdefhnNqStTv] <command>\n\n"
50 #else
51 "\tipfw -P <f-stack proc_id> [-abcdefhnNqStTv] <command>\n\n"
52 #endif
53 "where <command> is one of the following:\n\n"
54 "add [num] [set N] [prob x] RULE-BODY\n"
55 "{pipe|queue} N config PIPE-BODY\n"
56 "[pipe|queue] {zero|delete|show} [N{,N}]\n"
57 "nat N config {ip IPADDR|if IFNAME|log|deny_in|same_ports|unreg_only|unreg_cgn|\n"
58 "		reset|reverse|proxy_only|redirect_addr linkspec|\n"
59 "		redirect_port linkspec|redirect_proto linkspec}\n"
60 "set [disable N... enable N...] | move [rule] X to Y | swap X Y | show\n"
61 "set N {show|list|zero|resetlog|delete} [N{,N}] | flush\n"
62 "table N {add ip[/bits] [value] | delete ip[/bits] | flush | list}\n"
63 "table all {flush | list}\n"
64 "\n"
65 "RULE-BODY:	check-state [PARAMS] | ACTION [PARAMS] ADDR [OPTION_LIST]\n"
66 "ACTION:	check-state | allow | count | deny | unreach{,6} CODE |\n"
67 "               skipto N | {divert|tee} PORT | forward ADDR |\n"
68 "               pipe N | queue N | nat N | setfib FIB | reass\n"
69 "PARAMS: 	[log [logamount LOGLIMIT]] [altq QUEUE_NAME]\n"
70 "ADDR:		[ MAC dst src ether_type ] \n"
71 "		[ ip from IPADDR [ PORT ] to IPADDR [ PORTLIST ] ]\n"
72 "		[ ipv6|ip6 from IP6ADDR [ PORT ] to IP6ADDR [ PORTLIST ] ]\n"
73 "IPADDR:	[not] { any | me | ip/bits{x,y,z} | table(t[,v]) | IPLIST }\n"
74 "IP6ADDR:	[not] { any | me | me6 | ip6/bits | IP6LIST }\n"
75 "IP6LIST:	{ ip6 | ip6/bits }[,IP6LIST]\n"
76 "IPLIST:	{ ip | ip/bits | ip:mask }[,IPLIST]\n"
77 "OPTION_LIST:	OPTION [OPTION_LIST]\n"
78 "OPTION:	bridged | diverted | diverted-loopback | diverted-output |\n"
79 "	{dst-ip|src-ip} IPADDR | {dst-ip6|src-ip6|dst-ipv6|src-ipv6} IP6ADDR |\n"
80 "	{dst-port|src-port} LIST |\n"
81 "	estab | frag | {gid|uid} N | icmptypes LIST | in | out | ipid LIST |\n"
82 "	iplen LIST | ipoptions SPEC | ipprecedence | ipsec | iptos SPEC |\n"
83 "	ipttl LIST | ipversion VER | keep-state | layer2 | limit ... |\n"
84 "	icmp6types LIST | ext6hdr LIST | flow-id N[,N] | fib FIB |\n"
85 "	mac ... | mac-type LIST | proto LIST | {recv|xmit|via} {IF|IPADDR} |\n"
86 "	setup | {tcpack|tcpseq|tcpwin} NN | tcpflags SPEC | tcpoptions SPEC |\n"
87 "	tcpdatalen LIST | verrevpath | versrcreach | antispoof\n"
88 );
89 
90 #ifdef FSTACK
91 	ff_ipc_exit();
92 #endif
93 
94 	exit(0);
95 }
96 
97 /*
98  * Called with the arguments, including program name because getopt
99  * wants it to be present.
100  * Returns 0 if successful, 1 if empty command, errx() in case of errors.
101  * First thing we do is process parameters creating an argv[] array
102  * which includes the program name and a NULL entry at the end.
103  * If we are called with a single string, we split it on whitespace.
104  * Also, arguments with a trailing ',' are joined to the next one.
105  * The pointers (av[]) and data are in a single chunk of memory.
106  * av[0] points to the original program name, all other entries
107  * point into the allocated chunk.
108  */
109 static int
ipfw_main(int oldac,char ** oldav)110 ipfw_main(int oldac, char **oldav)
111 {
112 	int ch, ac;
113 	const char *errstr;
114 	char **av, **save_av;
115 	int do_acct = 0;		/* Show packet/byte count */
116 	int try_next = 0;		/* set if pipe cmd not found */
117 	int av_size;			/* compute the av size */
118 	char *av_p;			/* used to build the av list */
119 
120 #define WHITESP		" \t\f\v\n\r"
121 	if (oldac < 2)
122 		return 1;	/* need at least one argument */
123 
124 	if (oldac == 2) {
125 		/*
126 		 * If we are called with one argument, try to split it into
127 		 * words for subsequent parsing. Spaces after a ',' are
128 		 * removed by copying the string in-place.
129 		 */
130 		char *arg = oldav[1];	/* The string is the first arg. */
131 		int l = strlen(arg);
132 		int copy = 0;		/* 1 if we need to copy, 0 otherwise */
133 		int i, j;
134 
135 		for (i = j = 0; i < l; i++) {
136 			if (arg[i] == '#')	/* comment marker */
137 				break;
138 			if (copy) {
139 				arg[j++] = arg[i];
140 				copy = !strchr("," WHITESP, arg[i]);
141 			} else {
142 				copy = !strchr(WHITESP, arg[i]);
143 				if (copy)
144 					arg[j++] = arg[i];
145 			}
146 		}
147 		if (!copy && j > 0)	/* last char was a 'blank', remove it */
148 			j--;
149 		l = j;			/* the new argument length */
150 		arg[j++] = '\0';
151 		if (l == 0)		/* empty string! */
152 			return 1;
153 
154 		/*
155 		 * First, count number of arguments. Because of the previous
156 		 * processing, this is just the number of blanks plus 1.
157 		 */
158 		for (i = 0, ac = 1; i < l; i++)
159 			if (strchr(WHITESP, arg[i]) != NULL)
160 				ac++;
161 
162 		/*
163 		 * Allocate the argument list structure as a single block
164 		 * of memory, containing pointers and the argument
165 		 * strings. We include one entry for the program name
166 		 * because getopt expects it, and a NULL at the end
167 		 * to simplify further parsing.
168 		 */
169 		ac++;		/* add 1 for the program name */
170 		av_size = (ac+1) * sizeof(char *) + l + 1;
171 		av = safe_calloc(av_size, 1);
172 
173 		/*
174 		 * Init the argument pointer to the end of the array
175 		 * and copy arguments from arg[] to av[]. For each one,
176 		 * j is the initial character, i is the one past the end.
177 		 */
178 		av_p = (char *)&av[ac+1];
179 		for (ac = 1, i = j = 0; i < l; i++) {
180 			if (strchr(WHITESP, arg[i]) != NULL || i == l-1) {
181 				if (i == l-1)
182 					i++;
183 				bcopy(arg+j, av_p, i-j);
184 				av[ac] = av_p;
185 				av_p += i-j;	/* the length of the string */
186 				*av_p++ = '\0';
187 				ac++;
188 				j = i + 1;
189 			}
190 		}
191 	} else {
192 		/*
193 		 * If an argument ends with ',' join with the next one.
194 		 */
195 		int first, i, l=0;
196 
197 		/*
198 		 * Allocate the argument list structure as a single block
199 		 * of memory, containing both pointers and the argument
200 		 * strings. We include some space for the program name
201 		 * because getopt expects it.
202 		 * We add an extra pointer to the end of the array,
203 		 * to make simpler further parsing.
204 		 */
205 		for (i=0; i<oldac; i++)
206 			l += strlen(oldav[i]);
207 
208 		av_size = (oldac+1) * sizeof(char *) + l + oldac;
209 		av = safe_calloc(av_size, 1);
210 
211 		/*
212 		 * Init the argument pointer to the end of the array
213 		 * and copy arguments from arg[] to av[]
214 		 */
215 		av_p = (char *)&av[oldac+1];
216 		for (first = i = ac = 1, l = 0; i < oldac; i++) {
217 			char *arg = oldav[i];
218 			int k = strlen(arg);
219 
220 			l += k;
221 			if (arg[k-1] != ',' || i == oldac-1) {
222 				/* Time to copy. */
223 				av[ac] = av_p;
224 				for (l=0; first <= i; first++) {
225 					strcat(av_p, oldav[first]);
226 					av_p += strlen(oldav[first]);
227 				}
228 				*av_p++ = '\0';
229 				ac++;
230 				l = 0;
231 				first = i+1;
232 			}
233 		}
234 	}
235 
236 	/*
237 	 * set the progname pointer to the original string
238 	 * and terminate the array with null
239 	 */
240 	av[0] = oldav[0];
241 	av[ac] = NULL;
242 
243 	/* Set the force flag for non-interactive processes */
244 	if (!g_co.do_force)
245 		g_co.do_force = !isatty(STDIN_FILENO);
246 
247 #ifdef EMULATE_SYSCTL /* sysctl emulation */
248 	if ( ac >= 2 && !strcmp(av[1], "sysctl")) {
249 		char *s;
250 		int i;
251 
252 		if (ac != 3) {
253 			printf(	"sysctl emulation usage:\n"
254 				"	ipfw sysctl name[=value]\n"
255 				"	ipfw sysctl -a\n");
256 			return 0;
257 		}
258 		s = strchr(av[2], '=');
259 		if (s == NULL) {
260 			s = !strcmp(av[2], "-a") ? NULL : av[2];
261 			sysctlbyname(s, NULL, NULL, NULL, 0);
262 		} else {	/* ipfw sysctl x.y.z=value */
263 			/* assume an INT value, will extend later */
264 			if (s[1] == '\0') {
265 				printf("ipfw sysctl: missing value\n\n");
266 				return 0;
267 			}
268 			*s = '\0';
269 			i = strtol(s+1, NULL, 0);
270 			sysctlbyname(av[2], NULL, NULL, &i, sizeof(int));
271 		}
272 		return 0;
273 	}
274 #endif
275 
276 	/* Save arguments for final freeing of memory. */
277 	save_av = av;
278 
279 	optind = optreset = 1;	/* restart getopt() */
280 #ifndef FSTACK
281 	while ((ch = getopt(ac, av, "abcdDefhinNp:qs:STtv")) != -1)
282 #else
283 	while ((ch = getopt(ac, av, "abcdDefhinNp:qs:STtvP:")) != -1)
284 #endif
285 		switch (ch) {
286 		case 'a':
287 			do_acct = 1;
288 			break;
289 
290 		case 'b':
291 			g_co.comment_only = 1;
292 			g_co.do_compact = 1;
293 			break;
294 
295 		case 'c':
296 			g_co.do_compact = 1;
297 			break;
298 
299 		case 'd':
300 			g_co.do_dynamic = 1;
301 			break;
302 
303 		case 'D':
304 			g_co.do_dynamic = 2;
305 			break;
306 
307 		case 'e':
308 			/* nop for compatibility */
309 			break;
310 
311 		case 'f':
312 			g_co.do_force = 1;
313 			break;
314 
315 		case 'h': /* help */
316 			free(save_av);
317 			help();
318 			break;	/* NOTREACHED */
319 
320 		case 'i':
321 			g_co.do_value_as_ip = 1;
322 			break;
323 
324 		case 'n':
325 			g_co.test_only = 1;
326 			break;
327 
328 		case 'N':
329 			g_co.do_resolv = 1;
330 			break;
331 
332 		case 'p':
333 			errx(EX_USAGE, "An absolute pathname must be used "
334 			    "with -p option.");
335 			/* NOTREACHED */
336 
337 		case 'q':
338 			g_co.do_quiet = 1;
339 			break;
340 
341 		case 's': /* sort */
342 			g_co.do_sort = atoi(optarg);
343 			break;
344 
345 		case 'S':
346 			g_co.show_sets = 1;
347 			break;
348 
349 		case 't':
350 			g_co.do_time = TIMESTAMP_STRING;
351 			break;
352 
353 		case 'T':
354 			g_co.do_time = TIMESTAMP_NUMERIC;
355 			break;
356 
357 		case 'v': /* verbose */
358 			g_co.verbose = 1;
359 			break;
360 
361 #ifdef FSTACK
362 		case 'P':
363 			ff_set_proc_id(atoi(optarg));
364 			break;
365 #endif
366 
367 		default:
368 			free(save_av);
369 			return 1;
370 		}
371 
372 	ac -= optind;
373 	av += optind;
374 	NEED1("bad arguments, for usage summary ``ipfw''");
375 
376 	/*
377 	 * An undocumented behaviour of ipfw1 was to allow rule numbers first,
378 	 * e.g. "100 add allow ..." instead of "add 100 allow ...".
379 	 * In case, swap first and second argument to get the normal form.
380 	 */
381 	if (ac > 1 && isdigit(*av[0])) {
382 		char *p = av[0];
383 
384 		av[0] = av[1];
385 		av[1] = p;
386 	}
387 
388 	/*
389 	 * Optional: pipe, queue or nat.
390 	 */
391 	g_co.do_nat = 0;
392 	g_co.do_pipe = 0;
393 	g_co.use_set = 0;
394 	if (!strncmp(*av, "nat", strlen(*av)))
395 		g_co.do_nat = 1;
396 	else if (!strncmp(*av, "pipe", strlen(*av)))
397 		g_co.do_pipe = 1;
398 	else if (_substrcmp(*av, "queue") == 0)
399 		g_co.do_pipe = 2;
400 	else if (_substrcmp(*av, "flowset") == 0)
401 		g_co.do_pipe = 2;
402 	else if (_substrcmp(*av, "sched") == 0)
403 		g_co.do_pipe = 3;
404 	else if (!strncmp(*av, "set", strlen(*av))) {
405 		if (ac > 1 && isdigit(av[1][0])) {
406 			g_co.use_set = strtonum(av[1], 0, resvd_set_number,
407 					&errstr);
408 			if (errstr)
409 				errx(EX_DATAERR,
410 				    "invalid set number %s\n", av[1]);
411 			ac -= 2; av += 2; g_co.use_set++;
412 		}
413 	}
414 
415 	if (g_co.do_pipe || g_co.do_nat) {
416 		ac--;
417 		av++;
418 	}
419 	NEED1("missing command");
420 
421 	/*
422 	 * For pipes, queues and nats we normally say 'nat|pipe NN config'
423 	 * but the code is easier to parse as 'nat|pipe config NN'
424 	 * so we swap the two arguments.
425 	 */
426 	if ((g_co.do_pipe || g_co.do_nat) && ac > 1 && isdigit(*av[0])) {
427 		char *p = av[0];
428 
429 		av[0] = av[1];
430 		av[1] = p;
431 	}
432 
433 	if (g_co.use_set == 0) {
434 		if (_substrcmp(*av, "add") == 0)
435 			ipfw_add(av);
436 		else if (g_co.do_nat && _substrcmp(*av, "show") == 0)
437  			ipfw_show_nat(ac, av);
438 		else if (g_co.do_pipe && _substrcmp(*av, "config") == 0)
439 #ifdef DUMMYNET
440  			ipfw_config_pipe(ac, av);
441 #else
442  		{
443  			errx(EX_UNAVAILABLE, "ipfw_config_pipe not supported");
444  		}
445 #endif
446 		else if (g_co.do_nat && _substrcmp(*av, "config") == 0)
447  			ipfw_config_nat(ac, av);
448 		else if (_substrcmp(*av, "set") == 0)
449 			ipfw_sets_handler(av);
450 		else if (_substrcmp(*av, "table") == 0)
451 			ipfw_table_handler(ac, av);
452 		else if (_substrcmp(*av, "enable") == 0)
453 			ipfw_sysctl_handler(av, 1);
454 		else if (_substrcmp(*av, "disable") == 0)
455 			ipfw_sysctl_handler(av, 0);
456 		else
457 			try_next = 1;
458 	}
459 
460 	if (g_co.use_set || try_next) {
461 		if (_substrcmp(*av, "delete") == 0)
462 			ipfw_delete(av);
463 		else if (!strncmp(*av, "nat64clat", strlen(*av)))
464 			ipfw_nat64clat_handler(ac, av);
465 		else if (!strncmp(*av, "nat64stl", strlen(*av)))
466 			ipfw_nat64stl_handler(ac, av);
467 		else if (!strncmp(*av, "nat64lsn", strlen(*av)))
468 			ipfw_nat64lsn_handler(ac, av);
469 		else if (!strncmp(*av, "nptv6", strlen(*av)))
470 			ipfw_nptv6_handler(ac, av);
471 		else if (_substrcmp(*av, "flush") == 0)
472 			ipfw_flush(g_co.do_force);
473 		else if (_substrcmp(*av, "zero") == 0)
474 			ipfw_zero(ac, av, 0 /* IP_FW_ZERO */);
475 		else if (_substrcmp(*av, "resetlog") == 0)
476 			ipfw_zero(ac, av, 1 /* IP_FW_RESETLOG */);
477 		else if (_substrcmp(*av, "print") == 0 ||
478 			 _substrcmp(*av, "list") == 0)
479 			ipfw_list(ac, av, do_acct);
480 		else if (_substrcmp(*av, "show") == 0)
481 			ipfw_list(ac, av, 1 /* show counters */);
482 		else if (_substrcmp(*av, "table") == 0)
483 			ipfw_table_handler(ac, av);
484 		else if (_substrcmp(*av, "internal") == 0)
485 			ipfw_internal_handler(ac, av);
486 		else
487 			errx(EX_USAGE, "bad command `%s'", *av);
488 	}
489 
490 	/* Free memory allocated in the argument parsing. */
491 	free(save_av);
492 	return 0;
493 }
494 
495 
496 static void
ipfw_readfile(int ac,char * av[])497 ipfw_readfile(int ac, char *av[])
498 {
499 #define MAX_ARGS	32
500 	char buf[4096];
501 	char *progname = av[0];		/* original program name */
502 	const char *cmd = NULL;		/* preprocessor name, if any */
503 	const char *filename = av[ac-1]; /* file to read */
504 	int	c, lineno=0;
505 	FILE	*f = NULL;
506 	pid_t	preproc = 0;
507 
508 #ifndef FSTACK
509 	while ((c = getopt(ac, av, "cfNnp:qS")) != -1) {
510 #else
511 	while ((c = getopt(ac, av, "cfNnp:qSP:")) != -1) {
512 #endif
513 		switch(c) {
514 		case 'c':
515 			g_co.do_compact = 1;
516 			break;
517 
518 		case 'f':
519 			g_co.do_force = 1;
520 			break;
521 
522 		case 'N':
523 			g_co.do_resolv = 1;
524 			break;
525 
526 		case 'n':
527 			g_co.test_only = 1;
528 			break;
529 
530 		case 'p':
531 			/*
532 			 * ipfw -p cmd [args] filename
533 			 *
534 			 * We are done with getopt(). All arguments
535 			 * except the filename go to the preprocessor,
536 			 * so we need to do the following:
537 			 * - check that a filename is actually present;
538 			 * - advance av by optind-1 to skip arguments
539 			 *   already processed;
540 			 * - decrease ac by optind, to remove the args
541 			 *   already processed and the final filename;
542 			 * - set the last entry in av[] to NULL so
543 			 *   popen() can detect the end of the array;
544 			 * - set optind=ac to let getopt() terminate.
545 			 */
546 			if (optind == ac)
547 				errx(EX_USAGE, "no filename argument");
548 			cmd = optarg;
549 			av[ac-1] = NULL;
550 			av += optind - 1;
551 			ac -= optind;
552 			optind = ac;
553 			break;
554 
555 		case 'q':
556 			g_co.do_quiet = 1;
557 			break;
558 
559 		case 'S':
560 			g_co.show_sets = 1;
561 			break;
562 
563 #ifdef FSTACK
564 		case 'P':
565 			ff_set_proc_id(atoi(optarg));
566 			break;
567 #endif
568 
569 		default:
570 			errx(EX_USAGE, "bad arguments, for usage"
571 			     " summary ``ipfw''");
572 		}
573 
574 	}
575 
576 	if (cmd == NULL && ac != optind + 1)
577 		errx(EX_USAGE, "extraneous filename arguments %s", av[ac-1]);
578 
579 	if ((f = fopen(filename, "r")) == NULL)
580 		err(EX_UNAVAILABLE, "fopen: %s", filename);
581 
582 	if (cmd != NULL) {			/* pipe through preprocessor */
583 		int pipedes[2];
584 
585 		if (pipe(pipedes) == -1)
586 			err(EX_OSERR, "cannot create pipe");
587 
588 		preproc = fork();
589 		if (preproc == -1)
590 			err(EX_OSERR, "cannot fork");
591 
592 		if (preproc == 0) {
593 			/*
594 			 * Child, will run the preprocessor with the
595 			 * file on stdin and the pipe on stdout.
596 			 */
597 			if (dup2(fileno(f), 0) == -1
598 			    || dup2(pipedes[1], 1) == -1)
599 				err(EX_OSERR, "dup2()");
600 			fclose(f);
601 			close(pipedes[1]);
602 			close(pipedes[0]);
603 			execvp(cmd, av);
604 			err(EX_OSERR, "execvp(%s) failed", cmd);
605 		} else { /* parent, will reopen f as the pipe */
606 			fclose(f);
607 			close(pipedes[1]);
608 			if ((f = fdopen(pipedes[0], "r")) == NULL) {
609 				int savederrno = errno;
610 
611 				(void)kill(preproc, SIGTERM);
612 				errno = savederrno;
613 				err(EX_OSERR, "fdopen()");
614 			}
615 		}
616 	}
617 
618 	while (fgets(buf, sizeof(buf), f)) {		/* read commands */
619 		char linename[20];
620 		char *args[2];
621 
622 		lineno++;
623 		snprintf(linename, sizeof(linename), "Line %d", lineno);
624 #ifndef FSTACK
625 		setprogname(linename); /* XXX */
626 #endif
627 		args[0] = progname;
628 		args[1] = buf;
629 		ipfw_main(2, args);
630 	}
631 	fclose(f);
632 	if (cmd != NULL) {
633 		int status;
634 
635 		if (waitpid(preproc, &status, 0) == -1)
636 			errx(EX_OSERR, "waitpid()");
637 		if (WIFEXITED(status) && WEXITSTATUS(status) != EX_OK)
638 			errx(EX_UNAVAILABLE,
639 			    "preprocessor exited with status %d",
640 			    WEXITSTATUS(status));
641 		else if (WIFSIGNALED(status))
642 			errx(EX_UNAVAILABLE,
643 			    "preprocessor exited with signal %d",
644 			    WTERMSIG(status));
645 	}
646 }
647 
648 int
649 main(int ac, char *av[])
650 {
651 #if defined(_WIN32) && defined(TCC)
652 	{
653 		WSADATA wsaData;
654 		int ret=0;
655 		unsigned short wVersionRequested = MAKEWORD(2, 2);
656 		ret = WSAStartup(wVersionRequested, &wsaData);
657 		if (ret != 0) {
658 			/* Tell the user that we could not find a usable */
659 			/* Winsock DLL.				  */
660 			printf("WSAStartup failed with error: %d\n", ret);
661 			return 1;
662 		}
663 	}
664 #endif
665 	/*
666 	 * If the last argument is an absolute pathname, interpret it
667 	 * as a file to be preprocessed.
668 	 */
669 #ifdef FSTACK
670 	ff_ipc_init();
671 #endif
672 	if (ac > 1 && av[ac - 1][0] == '/') {
673 		if (access(av[ac - 1], R_OK) == 0)
674 			ipfw_readfile(ac, av);
675 		else
676 			err(EX_USAGE, "pathname: %s", av[ac - 1]);
677 	} else {
678 		if (ipfw_main(ac, av)) {
679 			errx(EX_USAGE,
680 			    "usage: ipfw [options]\n"
681 			    "do \"ipfw -h\" or \"man ipfw\" for details");
682 		}
683 	}
684 #ifdef FSTACK
685 	ff_ipc_exit();
686 #endif
687 	return EX_OK;
688 }
689