Handle unknown options in "dissect_ip_tcp_options()" better; we assume

that the only options that contain *no* length byte are the IP and TCP
EOL and NOP options so that we can treat unknown options as
VARIABLE_LENGTH with a minimum of 2, and at least be able to move on to
the next option by using the length in the option, rather than just
reporting the unknown option and processing no options after it.

svn path=/trunk/; revision=604

1 files changed, 35 insertions, 19 deletions

diff --git a/packet-ip.c b/packet-ip.c
index db4d4305d7..c858f014a6 100644
--- a/packet-ip.c
+++ b/packet-ip.c
@@ -1,7 +1,7 @@
 /* packet-ip.c
  * Routines for IP and miscellaneous IP protocol packet disassembly
  *
- * $Id: packet-ip.c,v 1.43 1999/08/28 08:31:26 guy Exp $
+ * $Id: packet-ip.c,v 1.44 1999/08/28 19:17:17 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@zing.org>
@@ -527,6 +527,12 @@ dissect_ip_tcp_options(const u_char *opd, int offset, guint length,
 {
   u_char            opt;
   const ip_tcp_opt *optp;
+  opt_len_type      len_type;
+  int               optlen;
+  char             *name;
+  char              name_str[7+1+1+2+2+1+1];	/* "Unknown (0x%02x)" */
+  void            (*dissect)(const struct ip_tcp_opt *, const u_char *,
+				int, guint, proto_tree *);
   guint             len;
 
   while (length > 0) {
@@ -536,19 +542,29 @@ dissect_ip_tcp_options(const u_char *opd, int offset, guint length,
         break;
     }
     if (optp == &opttab[nopts]) {
-      proto_tree_add_text(opt_tree, offset,      1, "Unknown (0x%02x)", opt);
-      /* We don't know how long this option is, so we don't know how much
-         of it to skip, so we just bail. */
-      return;
+      /* We assume that the only NO_LENGTH options are EOL and NOP options,
+         so that we can treat unknown options as VARIABLE_LENGTH with a
+	 minimum of 2, and at least be able to move on to the next option
+	 by using the length in the option. */
+      len_type = VARIABLE_LENGTH;
+      optlen = 2;
+       snprintf(name_str, sizeof name_str, "Unknown (0x%02x)", opt);
+      name = name_str;
+      dissect = NULL;
+    } else {
+      len_type = optp->len_type;
+      optlen = optp->optlen;
+      name = optp->name;
+      dissect = optp->dissect;
     }
     --length;      /* account for type byte */
-    if (optp->len_type != NO_LENGTH) {
+    if (len_type != NO_LENGTH) {
       /* Option has a length. Is it in the packet? */
       if (length == 0) {
         /* Bogus - packet must at least include option code byte and
            length byte! */
         proto_tree_add_text(opt_tree, offset,      1,
-              "%s (length byte past end of options)", optp->name);
+              "%s (length byte past end of options)", name);
         return;
       }
       len = *opd++;  /* total including type, len */
@@ -557,36 +573,36 @@ dissect_ip_tcp_options(const u_char *opd, int offset, guint length,
         /* Bogus - option length is too short to include option code and
            option length. */
         proto_tree_add_text(opt_tree, offset,      2,
-              "%s (with too-short option length = %u byte%s)", optp->name,
+              "%s (with too-short option length = %u byte%s)", name,
               plurality(len, "", "s"));
         return;
       } else if (len - 2 > length) {
         /* Bogus - option goes past the end of the header. */
         proto_tree_add_text(opt_tree, offset,      length,
               "%s (option length = %u byte%s says option goes past end of options)",
-	      optp->name, len, plurality(len, "", "s"));
+	      name, len, plurality(len, "", "s"));
         return;
-      } else if (optp->len_type == FIXED_LENGTH && len != optp->optlen) {
+      } else if (len_type == FIXED_LENGTH && len != optlen) {
         /* Bogus - option length isn't what it's supposed to be for this
            option. */
         proto_tree_add_text(opt_tree, offset,      len,
-              "%s (with option length = %u byte%s; should be %u)", optp->name,
-              len, plurality(len, "", "s"), optp->optlen);
+              "%s (with option length = %u byte%s; should be %u)", name,
+              len, plurality(len, "", "s"), optlen);
         return;
-      } else if (optp->len_type == VARIABLE_LENGTH && len < optp->optlen) {
+      } else if (len_type == VARIABLE_LENGTH && len < optlen) {
         /* Bogus - option length is less than what it's supposed to be for
            this option. */
         proto_tree_add_text(opt_tree, offset,      len,
-              "%s (with option length = %u byte%s; should be >= %u)", optp->name,
-              len, plurality(len, "", "s"), optp->optlen);
+              "%s (with option length = %u byte%s; should be >= %u)", name,
+              len, plurality(len, "", "s"), optlen);
         return;
       } else {
-        if (optp->dissect != NULL) {
+        if (dissect != NULL) {
           /* Option has a dissector. */
-          (*optp->dissect)(optp, opd, offset,      len, opt_tree);
+          (*dissect)(optp, opd, offset,      len, opt_tree);
         } else {
           /* Option has no data, hence no dissector. */
-          proto_tree_add_text(opt_tree, offset,    len, "%s", optp->name);
+          proto_tree_add_text(opt_tree, offset,    len, "%s", name);
         }
         len -= 2;	/* subtract size of type and length */
         offset += 2 + len;
@@ -594,7 +610,7 @@ dissect_ip_tcp_options(const u_char *opd, int offset, guint length,
       opd += len;
       length -= len;
     } else {
-      proto_tree_add_text(opt_tree, offset,      1, "%s", optp->name);
+      proto_tree_add_text(opt_tree, offset,      1, "%s", name);
       offset += 1;
     }
     if (opt == eol)