2 * copy diverted (or tee'd) packets to a file in 'tcpdump' format
3 * (ie. this uses the '-lpcap' routines).
6 * # ipfwpcap -r 8091 divt.log &
7 * # ipfw add 2864 divert 8091 ip from 128.432.53.82 to any
8 * # ipfw add 2864 divert 8091 ip from any to 128.432.53.82
10 * the resulting dump file can be read with ...
11 * # tcpdump -nX -r divt.log
14 * Written by P Kern { pkern [AT] cns.utoronto.ca }
16 * Copyright (c) 2004 University of Toronto. All rights reserved.
17 * Anyone may use or copy this software except that this copyright
18 * notice remain intact and that credit is given where it is due.
19 * The University of Toronto and the author make no warranty and
20 * accept no liability for this software.
22 * From: Header: /local/src/local.lib/SRC/ipfwpcap/RCS/ipfwpcap.c,v 1.4 2004/01/15 16:19:07 pkern Exp
35 #include <sys/types.h>
37 #include <sys/param.h> /* for MAXPATHLEN */
38 #include <sys/socket.h>
39 #include <netinet/in.h>
41 #include <netinet/in_systm.h> /* for IP_MAXPACKET */
42 #include <netinet/ip.h> /* for IP_MAXPACKET */
46 /* XXX normally defined in config.h */
47 #define HAVE_STRLCPY 1
48 #define HAVE_SNPRINTF 1
49 #define HAVE_VSNPRINTF 1
50 #include <pcap-int.h> /* see pcap(3) and /usr/src/contrib/libpcap/. */
53 #define BUFMAX IP_MAXPACKET
59 #define MAXPATHLEN 1024
63 static int reflect = 0; /* 1 == write packet back to socket. */
65 static ssize_t totbytes = 0, maxbytes = 0;
66 static ssize_t totpkts = 0, maxpkts = 0;
68 static char *prog = NULL;
69 static char pidfile[MAXPATHLEN];
77 (void) unlink(pidfile);
83 * - save my own pid in /var/run/$0.{port#}.pid
91 if (pidfile[0] == '\0') {
92 p = strrchr(prog, '/');
93 p = (p == NULL) ? prog : p + 1;
95 snprintf(pidfile, sizeof pidfile,
96 "%s%s.%d.pid", _PATH_VARRUN, p, pn);
99 fd = open(pidfile, O_WRONLY|O_CREAT|O_EXCL, 0644);
105 siginterrupt(SIGTERM, 1);
106 siginterrupt(SIGHUP, 1);
107 signal(SIGTERM, quit);
108 signal(SIGHUP, quit);
109 signal(SIGINT, quit);
111 snprintf(numbuf, sizeof numbuf, "%d\n", getpid());
112 if (write(fd, numbuf, strlen(numbuf)) < 0) {
125 " %s [-dr] [-b maxbytes] [-p maxpkts] [-P pidfile] portnum dumpfile\n"
128 " '-d' = enable debugging messages.\n"
129 " '-r' = reflect. write packets back to the divert socket.\n"
130 " (ie. simulate the original intent of \"ipfw tee\").\n"
131 " '-rr' = indicate that it is okay to quit if packet-count or\n"
132 " byte-count limits are reached (see the NOTE below\n"
133 " about what this implies).\n"
134 " '-b bytcnt' = stop dumping after {bytcnt} bytes.\n"
135 " '-p pktcnt' = stop dumping after {pktcnt} packets.\n"
136 " '-P pidfile' = alternate file to store the PID\n"
137 " (default: /var/run/%s.{portnum}.pid).\n"
139 " portnum = divert(4) socket port number.\n"
140 " dumpfile = file to write captured packets (tcpdump format).\n"
141 " (specify '-' to write packets to stdout).\n"
143 "The '-r' option should not be necessary, but because \"ipfw tee\" is broken\n"
144 "(see BUGS in ipfw(8) for details) this feature can be used along with\n"
145 "an \"ipfw divert\" rule to simulate the original intent of \"ipfw tee\".\n"
147 "NOTE: With an \"ipfw divert\" rule, diverted packets will silently\n"
148 " disappear if there is nothing listening to the divert socket.\n"
154 main(int ac, char *av[])
156 int r, sd, portnum, l;
157 struct sockaddr_in sin;
165 char *dumpf, buf[BUFMAX];
169 struct pcap_pkthdr phd;
173 while ((r = getopt(ac, av, "drb:p:P:")) != -1) {
182 maxbytes = (ssize_t) atol(optarg);
185 maxpkts = (ssize_t) atoi(optarg);
188 strcpy(pidfile, optarg);
197 if ((ac - optind) != 2 || errflg)
200 portnum = atoi(av[optind++]);
203 if (debug) fprintf(stderr, "bind to %d.\ndump to '%s'.\n", portnum, dumpf);
205 if ((r = socket(PF_INET, SOCK_RAW, IPPROTO_DIVERT)) == -1) {
206 perror("socket(DIVERT)");
211 sin.sin_port = htons(portnum);
212 sin.sin_family = AF_INET;
213 sin.sin_addr.s_addr = INADDR_ANY;
215 if (bind(sd, (struct sockaddr *)&sin, sizeof(sin)) == -1) {
216 perror("bind(divert)");
220 p = pcap_open_dead(DLT_RAW, BUFMAX);
221 dp = pcap_dump_open(p, dumpf);
223 pcap_perror(p, dumpf);
234 r = select(nfd, &rds, NULL, NULL, NULL);
236 if (errno == EINTR) continue;
241 if (!FD_ISSET(sd, &rds))
246 * use recvfrom(3 and sendto(3) as in natd(8).
247 * see /usr/src/sbin/natd/natd.c
248 * see ipfw(8) about using 'divert' and 'tee'.
255 nr = recvfrom(sd, buf, sizeof(buf), 0, (struct sockaddr *)&sin, &l);
256 if (debug) fprintf(stderr, "recvfrom(%d) = %zd (%d)\n", sd, nr, l);
257 if (nr < 0 && errno != EINTR) {
258 perror("recvfrom(sd)");
261 if (nr <= 0) continue;
265 * write packet back so it can continue
266 * being processed by any further IPFW rules.
269 r = sendto(sd, buf, nr, 0, (struct sockaddr *)&sin, l);
270 if (debug) fprintf(stderr, " sendto(%d) = %d\n", sd, r);
271 if (r < 0) { perror("sendto(sd)"); quit(13); }
275 * check maximums, if any.
276 * but don't quit if must continue reflecting packets.
280 if (totpkts > maxpkts) {
281 if (reflect == 1) continue;
287 if (totbytes > maxbytes) {
288 if (reflect == 1) continue;
294 * save packet in tcpdump(1) format. see pcap(3).
295 * divert packets are fully assembled. see ipfw(8).
297 (void) gettimeofday(&(phd.ts), NULL);
298 phd.caplen = phd.len = nr;
299 pcap_dump((u_char *)dp, &phd, buf);
300 if (ferror((FILE *)dp)) { perror(dumpf); quit(14); }
301 (void) fflush((FILE *)dp);