Add a "-s" flag to editcap, to make it truncate packets to a specified

snapshot length before writing them to the output file; this may come in
handy if you are translating the file to a different format so that it
can be read by a program that can't handle packets above a certain size
(e.g., the snoop in Solaris 2.5.1 or 2.6, which reject Ethernet packets
larger than the Ethernet MTU, and thus can't handle gigabit Ethernet
captures using jumbo frames).

svn path=/trunk/; revision=1891

1 files changed, 22 insertions, 3 deletions

diff --git a/editcap.c b/editcap.c
index a2a524ae07..24562ee3ea 100644
--- a/editcap.c
+++ b/editcap.c
@@ -1,7 +1,7 @@
 /* Edit capture files.  We can delete records, or simply convert from one 
  * format to another format.
  *
- * $Id: editcap.c,v 1.8 2000/04/17 14:52:32 gram Exp $
+ * $Id: editcap.c,v 1.9 2000/04/27 00:31:23 guy Exp $
  *
  * Originally written by Richard Sharpe.
  * Improved by Guy Harris.
@@ -53,6 +53,7 @@ static int keep_em = 0;
 static int out_file_type = WTAP_FILE_PCAP;   /* default to "libpcap"   */
 static int out_frame_type = -2;              /* Leave frame type alone */
 static int verbose = 0;                      /* Not so verbose         */
+static int snaplen = 0;                      /* No limit               */
 
 /* Add a selection item, a simple parser for now */
 
@@ -133,6 +134,7 @@ edit_callback(u_char *user, const struct wtap_pkthdr *phdr, int offset,
 {
   callback_arg *argp = (callback_arg *)user;
   int err;
+  struct wtap_pkthdr snap_phdr;
 
   if ((!selected(count) && !keep_em) ||
       (selected(count) && keep_em)) {
@@ -140,7 +142,14 @@ edit_callback(u_char *user, const struct wtap_pkthdr *phdr, int offset,
     if (verbose)
       printf("Record: %u\n", count);
 
-    /* We simply write it, we could do other things, like modify it */
+    /* We simply write it, perhaps after truncating it; we could do other
+       things, like modify it. */
+
+    if (snaplen != 0 && phdr->caplen > snaplen) {
+      snap_phdr = *phdr;
+      snap_phdr.caplen = snaplen;
+      phdr = &snap_phdr;
+    }
 
     if (!wtap_dump(argp->pdh, phdr, buf, &err)) {
 
@@ -194,10 +203,11 @@ int main(int argc, char *argv[])
   extern char *optarg;
   extern int optind;
   char opt;
+  char *p;
 
   /* Process the options first */
 
-  while ((opt = getopt(argc, argv, "T:F:rv")) != EOF) {
+  while ((opt = getopt(argc, argv, "T:F:rvs:")) != EOF) {
 
     switch (opt) {
 
@@ -227,6 +237,15 @@ int main(int argc, char *argv[])
       keep_em = !keep_em;  /* Just invert */
       break;
 
+    case 's':
+      snaplen = strtol(optarg, &p, 10);
+      if (p == optarg || *p != '\0') {
+      	fprintf(stderr, "editcap: \"%s\" is not a valid snapshot length\n",
+      	    optarg);
+      	exit(1);
+      }
+      break;
+
     case 'h':
       usage();
       exit(1);