306 lines
6.6 KiB
C
306 lines
6.6 KiB
C
/*
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* copy diverted (or tee'd) packets to a file in 'tcpdump' format
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* (ie. this uses the '-lpcap' routines).
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*
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* example usage:
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* # ipfwpcap -r 8091 divt.log &
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* # ipfw add 2864 divert 8091 ip from 128.432.53.82 to any
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* # ipfw add 2864 divert 8091 ip from any to 128.432.53.82
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*
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* the resulting dump file can be read with ...
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* # tcpdump -nX -r divt.log
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*/
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/*
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* Written by P Kern { pkern [AT] cns.utoronto.ca }
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*
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* Copyright (c) 2004 University of Toronto. All rights reserved.
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* Anyone may use or copy this software except that this copyright
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* notice remain intact and that credit is given where it is due.
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* The University of Toronto and the author make no warranty and
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* accept no liability for this software.
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*
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* From: Header: /local/src/local.lib/SRC/ipfwpcap/RCS/ipfwpcap.c,v 1.4 2004/01/15 16:19:07 pkern Exp
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*
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* $FreeBSD$
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*/
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#include <stdio.h>
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#include <errno.h>
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#include <paths.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/time.h>
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#include <sys/param.h> /* for MAXPATHLEN */
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h> /* for IP_MAXPACKET */
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#include <netinet/ip.h> /* for IP_MAXPACKET */
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#include <net/bpf.h>
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/* XXX normally defined in config.h */
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#define HAVE_STRLCPY 1
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#define HAVE_SNPRINTF 1
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#define HAVE_VSNPRINTF 1
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#include <pcap-int.h> /* see pcap(3) and /usr/src/contrib/libpcap/. */
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#ifdef IP_MAXPACKET
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#define BUFMAX IP_MAXPACKET
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#else
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#define BUFMAX 65535
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#endif
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#ifndef MAXPATHLEN
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#define MAXPATHLEN 1024
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#endif
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static int debug = 0;
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static int reflect = 0; /* 1 == write packet back to socket. */
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static ssize_t totbytes = 0, maxbytes = 0;
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static ssize_t totpkts = 0, maxpkts = 0;
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static char *prog = NULL;
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static char pidfile[MAXPATHLEN];
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/*
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* tidy up.
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*/
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static void
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quit(int sig)
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{
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(void) unlink(pidfile);
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exit(sig);
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}
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/*
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* do the "paper work"
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* - save my own pid in /var/run/$0.{port#}.pid
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*/
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static void
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okay(int pn)
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{
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int fd;
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char *p, numbuf[80];
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if (pidfile[0] == '\0') {
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p = strrchr(prog, '/');
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p = (p == NULL) ? prog : p + 1;
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snprintf(pidfile, sizeof pidfile,
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"%s%s.%d.pid", _PATH_VARRUN, p, pn);
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}
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fd = open(pidfile, O_WRONLY|O_CREAT|O_EXCL, 0644);
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if (fd < 0) {
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perror(pidfile);
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exit(21);
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}
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siginterrupt(SIGTERM, 1);
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siginterrupt(SIGHUP, 1);
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signal(SIGTERM, quit);
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signal(SIGHUP, quit);
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signal(SIGINT, quit);
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snprintf(numbuf, sizeof numbuf, "%d\n", getpid());
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if (write(fd, numbuf, strlen(numbuf)) < 0) {
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perror(pidfile);
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quit(23);
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}
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(void) close(fd);
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}
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static void
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usage(void)
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{
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fprintf(stderr,
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"\n"
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"usage:\n"
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" %s [-dr] [-b maxbytes] [-p maxpkts] [-P pidfile] portnum dumpfile\n"
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"\n"
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"where:\n"
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" '-d' = enable debugging messages.\n"
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" '-r' = reflect. write packets back to the divert socket.\n"
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" (ie. simulate the original intent of \"ipfw tee\").\n"
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" '-rr' = indicate that it is okay to quit if packet-count or\n"
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" byte-count limits are reached (see the NOTE below\n"
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" about what this implies).\n"
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" '-b bytcnt' = stop dumping after {bytcnt} bytes.\n"
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" '-p pktcnt' = stop dumping after {pktcnt} packets.\n"
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" '-P pidfile' = alternate file to store the PID\n"
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" (default: /var/run/%s.{portnum}.pid).\n"
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"\n"
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" portnum = divert(4) socket port number.\n"
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" dumpfile = file to write captured packets (tcpdump format).\n"
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" (specify '-' to write packets to stdout).\n"
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"\n"
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"The '-r' option should not be necessary, but because \"ipfw tee\" is broken\n"
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"(see BUGS in ipfw(8) for details) this feature can be used along with\n"
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"an \"ipfw divert\" rule to simulate the original intent of \"ipfw tee\".\n"
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"\n"
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"NOTE: With an \"ipfw divert\" rule, diverted packets will silently\n"
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" disappear if there is nothing listening to the divert socket.\n"
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"\n", prog, prog);
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exit(1);
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}
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int
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main(int ac, char *av[])
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{
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int r, sd, portnum, l;
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struct sockaddr_in sin;
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int errflg = 0;
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int nfd;
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fd_set rds;
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ssize_t nr;
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char *dumpf, buf[BUFMAX];
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pcap_t *p;
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pcap_dumper_t *dp;
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struct pcap_pkthdr phd;
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prog = av[0];
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while ((r = getopt(ac, av, "drb:p:P:")) != -1) {
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switch (r) {
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case 'd':
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debug++;
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break;
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case 'r':
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reflect++;
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break;
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case 'b':
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maxbytes = (ssize_t) atol(optarg);
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break;
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case 'p':
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maxpkts = (ssize_t) atoi(optarg);
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break;
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case 'P':
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strcpy(pidfile, optarg);
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break;
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case '?':
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default:
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errflg++;
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break;
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}
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}
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if ((ac - optind) != 2 || errflg)
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usage();
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portnum = atoi(av[optind++]);
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dumpf = av[optind];
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if (debug) fprintf(stderr, "bind to %d.\ndump to '%s'.\n", portnum, dumpf);
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if ((r = socket(PF_INET, SOCK_RAW, IPPROTO_DIVERT)) == -1) {
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perror("socket(DIVERT)");
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exit(2);
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}
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sd = r;
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sin.sin_port = htons(portnum);
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sin.sin_family = AF_INET;
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sin.sin_addr.s_addr = INADDR_ANY;
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if (bind(sd, (struct sockaddr *)&sin, sizeof(sin)) == -1) {
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perror("bind(divert)");
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exit(3);
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}
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p = pcap_open_dead(DLT_RAW, BUFMAX);
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dp = pcap_dump_open(p, dumpf);
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if (dp == NULL) {
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pcap_perror(p, dumpf);
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exit(4);
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}
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okay(portnum);
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nfd = sd + 1;
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for (;;) {
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FD_ZERO(&rds);
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FD_SET(sd, &rds);
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r = select(nfd, &rds, NULL, NULL, NULL);
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if (r == -1) {
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if (errno == EINTR) continue;
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perror("select");
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quit(11);
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}
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if (!FD_ISSET(sd, &rds))
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/* hmm. no work. */
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continue;
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/*
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* use recvfrom(3 and sendto(3) as in natd(8).
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* see /usr/src/sbin/natd/natd.c
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* see ipfw(8) about using 'divert' and 'tee'.
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*/
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/*
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* read packet.
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*/
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l = sizeof(sin);
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nr = recvfrom(sd, buf, sizeof(buf), 0, (struct sockaddr *)&sin, &l);
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if (debug) fprintf(stderr, "recvfrom(%d) = %zd (%d)\n", sd, nr, l);
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if (nr < 0 && errno != EINTR) {
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perror("recvfrom(sd)");
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quit(12);
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}
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if (nr <= 0) continue;
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if (reflect) {
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/*
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* write packet back so it can continue
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* being processed by any further IPFW rules.
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*/
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l = sizeof(sin);
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r = sendto(sd, buf, nr, 0, (struct sockaddr *)&sin, l);
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if (debug) fprintf(stderr, " sendto(%d) = %d\n", sd, r);
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if (r < 0) { perror("sendto(sd)"); quit(13); }
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}
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/*
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* check maximums, if any.
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* but don't quit if must continue reflecting packets.
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*/
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if (maxpkts) {
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totpkts++;
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if (totpkts > maxpkts) {
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if (reflect == 1) continue;
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quit(0);
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}
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}
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if (maxbytes) {
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totbytes += nr;
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if (totbytes > maxbytes) {
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if (reflect == 1) continue;
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quit(0);
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}
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}
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/*
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* save packet in tcpdump(1) format. see pcap(3).
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* divert packets are fully assembled. see ipfw(8).
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*/
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(void) gettimeofday(&(phd.ts), NULL);
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phd.caplen = phd.len = nr;
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pcap_dump((u_char *)dp, &phd, buf);
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if (ferror((FILE *)dp)) { perror(dumpf); quit(14); }
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(void) fflush((FILE *)dp);
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}
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quit(0);
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}
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