--- main.c.orig	Tue Apr 20 21:40:14 1999
+++ main.c	Sun Oct 10 21:31:33 1999
@@ -63,7 +63,7 @@
   fprintf(stderr, "%s version %s by Jeremy Elson <jelson@circlemud.org>\n\n",
 		 PACKAGE, VERSION);
   fprintf(stderr, "usage: %s [-chpsv] [-b max_bytes] [-d debug_level] [-f max_fds]\n", progname);
-  fprintf(stderr, "          [-i iface] [expression]\n\n");
+  fprintf(stderr, "          [-i iface] [-r file] [expression]\n\n");
   fprintf(stderr, "        -b: max number of bytes per flow to save\n");
   fprintf(stderr, "        -c: console print only (don't create files)\n");
   fprintf(stderr, "        -d: debug level; default is %d\n", DEFAULT_DEBUG_LEVEL);
@@ -72,6 +72,7 @@
   fprintf(stderr, "        -i: network interface on which to listen\n");
   fprintf(stderr, "            (type \"ifconfig -a\" for a list of interfaces)\n");
   fprintf(stderr, "        -p: don't use promiscuous mode\n");
+  fprintf(stderr, "        -r: read packets from file\n");
   fprintf(stderr, "        -s: strip non-printable characters (change to '.')\n");
   fprintf(stderr, "        -v: verbose operation equivalent to -d 10\n");
   fprintf(stderr, "expression: tcpdump-like filtering expression\n");
@@ -89,6 +90,7 @@
   int need_usage = 0;
 
   char *device = NULL;
+  char *infile = NULL;
   char *expression = NULL;
   pcap_t *pd;
   struct bpf_program fcode;
@@ -98,7 +100,7 @@
 
   opterr = 0;
 
-  while ((arg = getopt(argc, argv, "b:cd:f:hi:psv")) != EOF) {
+  while ((arg = getopt(argc, argv, "b:cd:f:hi:pr:sv")) != EOF) {
     switch (arg) {
     case 'b':
       if ((bytes_per_flow = atoi(optarg)) < 0) {
@@ -140,6 +142,9 @@
       no_promisc = 1;
       DEBUG(10) ("NOT turning on promiscuous mode");
       break;
+    case 'r':
+      infile = optarg;
+      break;
     case 'v':
       debug_level = 10;
       break;
@@ -160,23 +165,32 @@
   DEBUG(10) ("%s version %s by Jeremy Elson <jelson@circlemud.org>",
 	     PACKAGE, VERSION);
 
-  /* if the user didn't specify a device, try to find a reasonable one */
-  if (device == NULL)
-    if ((device = pcap_lookupdev(error)) == NULL)
+  if (infile != NULL) {
+    /* Since we don't need network access, drop root privileges */
+    setuid(getuid());
+
+    /* open the capture file */
+    if ((pd = pcap_open_offline(infile, error)) == NULL)
       die(error);
 
-  /* make sure we can open the device */
-  if ((pd = pcap_open_live(device, SNAPLEN, !no_promisc, 1000, error)) == NULL)
-    die(error);
+    /* get the handler for this kind of packets */
+    handler = find_handler(pcap_datalink(pd), infile);
+  } else {
+    /* if the user didn't specify a device, try to find a reasonable one */
+    if (device == NULL)
+      if ((device = pcap_lookupdev(error)) == NULL)
+	die(error);
 
-  /* drop root privileges - we don't need them any more */
-  setuid(getuid());
+    /* make sure we can open the device */
+    if ((pd = pcap_open_live(device, SNAPLEN, !no_promisc, 1000, error)) == NULL)
+      die(error);
 
-  /* remember what datalink type the selected network interface is */
-  dlt = pcap_datalink(pd);
+    /* drop root privileges - we don't need them any more */
+    setuid(getuid());
 
-  /* get the handler for this network interface */
-  handler = find_handler(dlt, device);
+    /* get the handler for this kind of packets */
+    handler = find_handler(pcap_datalink(pd), device);
+  }
 
   /* get the user's expression out of argv */
   expression = copy_argv(&argv[optind]);
@@ -223,7 +237,8 @@
   init_flow_state();
 
   /* start listening! */
-  DEBUG(1) ("listening on %s", device);
+  if (infile == NULL)
+    DEBUG(1) ("listening on %s", device);
   if (pcap_loop(pd, -1, handler, NULL) < 0)
     die(pcap_geterr(pd));