Wireshark · Ethereal-dev: [Ethereal-dev] Patch: Correction for DNS A6 RR decoding.

[Per Flock <per.flock@xxxxxxxx>]

Please find attached a proposed patch to fix an error in DNS A6 resource record decoding.

/Per

Index: packet-dns.c
===================================================================
RCS file: /cvsroot/ethereal/packet-dns.c,v
retrieving revision 1.55
diff -u -r1.55 packet-dns.c
--- packet-dns.c	2000/10/11 04:12:05	1.55
+++ packet-dns.c	2000/10/17 11:34:42
@@ -1477,7 +1477,7 @@
       }
       pre_len = pd[cur_offset++];
       suf_len = 128 - pre_len;
-      suf_octet_count = (suf_len - 1) / 8 + 1;
+      suf_octet_count = suf_len ? (suf_len - 1) / 8 + 1 : 0;
       if (!BYTES_ARE_IN_FRAME(cur_offset, suf_octet_count)) {
         /* We ran past the end of the captured data in the packet. */
         return 0;
@@ -1490,11 +1490,15 @@
         suffix[suf_offset] = pd[cur_offset++];
       }
 
-      pname_len = get_dns_name(pd, cur_offset, dns_data_offset, 
-                               pname, sizeof(pname));
-      if (pname_len < 0) {
-        /* We ran past the end of the captured data in the packet. */
-        return 0;
+      if (pre_len > 0) {
+        pname_len = get_dns_name(pd, cur_offset, dns_data_offset, 
+                                 pname, sizeof(pname));
+        if (pname_len < 0) {
+          /* We ran past the end of the captured data in the packet. */
+          return 0;
+        }
+      } else {
+        strcpy(pname, "");   
       }
 
       if (fd != NULL) {
@@ -1507,12 +1511,16 @@
         proto_tree_add_text(rr_tree, NullTVB, a6_offset, 1, 
                             "Prefix len: %u", pre_len);
         a6_offset++;
-        proto_tree_add_text(rr_tree, NullTVB, a6_offset, suf_octet_count,
-                            "Address suffix: %s", 
-                            ip6_to_str((struct e_in6_addr *)&suffix));
-        a6_offset += suf_octet_count;
-        proto_tree_add_text(rr_tree, NullTVB, a6_offset, pname_len, 
-                            "Prefix name: %s", pname);
+        if (suf_len) {
+          proto_tree_add_text(rr_tree, NullTVB, a6_offset, suf_octet_count,
+                              "Address suffix: %s", 
+                              ip6_to_str((struct e_in6_addr *)&suffix));
+          a6_offset += suf_octet_count;
+        }
+        if (pre_len > 0) {
+          proto_tree_add_text(rr_tree, NullTVB, a6_offset, pname_len, 
+                              "Prefix name: %s", pname);
+        }
         proto_item_set_text(trr, "%s: type %s, class %s, addr %d %s %s",
                             name, 
                             type_name,