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 */
44 /* XXX normally defined in config.h */
45 #define HAVE_STRLCPY 1
46 #define HAVE_SNPRINTF 1
47 #define HAVE_VSNPRINTF 1
48 #include <pcap-int.h> /* see pcap(3) and /usr/src/contrib/libpcap/. */
51 #define BUFMAX IP_MAXPACKET
57 #define MAXPATHLEN 1024
61 static int reflect = 0; /* 1 == write packet back to socket. */
63 static ssize_t totbytes = 0, maxbytes = 0;
64 static ssize_t totpkts = 0, maxpkts = 0;
66 static char *prog = NULL;
67 static char pidfile[MAXPATHLEN];
75 (void) unlink(pidfile);
81 * - save my own pid in /var/run/$0.{port#}.pid
89 if (pidfile[0] == '\0') {
90 p = rindex(prog, '/');
91 p = (p == NULL) ? prog : p + 1;
93 snprintf(pidfile, sizeof pidfile,
94 "%s%s.%d.pid", _PATH_VARRUN, p, pn);
97 fd = open(pidfile, O_WRONLY|O_CREAT|O_EXCL, 0644);
103 siginterrupt(SIGTERM, 1);
104 siginterrupt(SIGHUP, 1);
105 signal(SIGTERM, quit);
106 signal(SIGHUP, quit);
107 signal(SIGINT, quit);
109 snprintf(numbuf, sizeof numbuf, "%d\n", getpid());
110 if (write(fd, numbuf, strlen(numbuf)) < 0) {
123 " %s [-dr] [-b maxbytes] [-p maxpkts] [-P pidfile] portnum dumpfile\n"
126 " '-d' = enable debugging messages.\n"
127 " '-r' = reflect. write packets back to the divert socket.\n"
128 " (ie. simulate the original intent of \"ipfw tee\").\n"
129 " '-rr' = indicate that it is okay to quit if packet-count or\n"
130 " byte-count limits are reached (see the NOTE below\n"
131 " about what this implies).\n"
132 " '-b bytcnt' = stop dumping after {bytcnt} bytes.\n"
133 " '-p pktcnt' = stop dumping after {pktcnt} packets.\n"
134 " '-P pidfile' = alternate file to store the PID\n"
135 " (default: /var/run/%s.{portnum}.pid).\n"
137 " portnum = divert(4) socket port number.\n"
138 " dumpfile = file to write captured packets (tcpdump format).\n"
139 " (specify '-' to write packets to stdout).\n"
141 "The '-r' option should not be necessary, but because \"ipfw tee\" is broken\n"
142 "(see BUGS in ipfw(8) for details) this feature can be used along with\n"
143 "an \"ipfw divert\" rule to simulate the original intent of \"ipfw tee\".\n"
145 "NOTE: With an \"ipfw divert\" rule, diverted packets will silently\n"
146 " disappear if there is nothing listening to the divert socket.\n"
152 main(int ac, char *av[])
154 int r, sd, portnum, l;
155 struct sockaddr_in sin;
163 char *dumpf, buf[BUFMAX];
167 struct pcap_pkthdr phd;
171 while ((r = getopt(ac, av, "drb:p:P:")) != -1) {
180 maxbytes = (ssize_t) atol(optarg);
183 maxpkts = (ssize_t) atoi(optarg);
186 strcpy(pidfile, optarg);
195 if ((ac - optind) != 2 || errflg)
198 portnum = atoi(av[optind++]);
201 if (debug) fprintf(stderr, "bind to %d.\ndump to '%s'.\n", portnum, dumpf);
203 if ((r = socket(PF_INET, SOCK_RAW, IPPROTO_DIVERT)) == -1) {
204 perror("socket(DIVERT)");
209 sin.sin_port = htons(portnum);
210 sin.sin_family = AF_INET;
211 sin.sin_addr.s_addr = INADDR_ANY;
213 if (bind(sd, (struct sockaddr *)&sin, sizeof(sin)) == -1) {
214 perror("bind(divert)");
218 p = pcap_open_dead(DLT_RAW, BUFMAX);
219 dp = pcap_dump_open(p, dumpf);
221 pcap_perror(p, dumpf);
232 r = select(nfd, &rds, NULL, NULL, NULL);
234 if (errno == EINTR) continue;
239 if (!FD_ISSET(sd, &rds))
244 * use recvfrom(3 and sendto(3) as in natd(8).
245 * see /usr/src/sbin/natd/natd.c
246 * see ipfw(8) about using 'divert' and 'tee'.
253 nr = recvfrom(sd, buf, sizeof(buf), 0, (struct sockaddr *)&sin, &l);
254 if (debug) fprintf(stderr, "recvfrom(%d) = %zd (%d)\n", sd, nr, l);
255 if (nr < 0 && errno != EINTR) {
256 perror("recvfrom(sd)");
259 if (nr <= 0) continue;
263 * write packet back so it can continue
264 * being processed by any further IPFW rules.
267 r = sendto(sd, buf, nr, 0, (struct sockaddr *)&sin, l);
268 if (debug) fprintf(stderr, " sendto(%d) = %d\n", sd, r);
269 if (r < 0) { perror("sendto(sd)"); quit(13); }
273 * check maximums, if any.
274 * but don't quit if must continue reflecting packets.
278 if (totpkts > maxpkts) {
279 if (reflect == 1) continue;
285 if (totbytes > maxbytes) {
286 if (reflect == 1) continue;
292 * save packet in tcpdump(1) format. see pcap(3).
293 * divert packets are fully assembled. see ipfw(8).
295 (void) gettimeofday(&(phd.ts), NULL);
296 phd.caplen = phd.len = nr;
297 pcap_dump((u_char *)dp, &phd, buf);
298 if (ferror((FILE *)dp)) { perror(dumpf); quit(14); }
299 (void) fflush((FILE *)dp);