How to write a dissector for a protocol that runs on top of TCP or UDP both

Question

I'm a long time developer who is new to wireshark. I'm actually trying to update the built in C12.22 dissector that is for TCP currently to also use UDP as well, everything else the same. If someone could just send me a new x64 1.8.6 asn1.dll that would be super awesome. If not please tell me how to setup a new dissector or modify the C12.22 dissector to use both TCP and UDP underneath. Thanks.

Answer 1

Raise a bug report, including a small sample trace to try a patch with.

A patch would look something like:

Index: asn1/c1222/packet-c1222-template.c
===================================================================
--- asn1/c1222/packet-c1222-template.c  (revision 49103)
+++ asn1/c1222/packet-c1222-template.c  (working copy)
@@ -79,6 +79,7 @@
 #define C1222_CMD_TIMING_SETUP 0x71
static dissector_handle_t c1222_handle=NULL;
+static dissector_handle_t c1222_udp_handle=NULL;
/* Initialize the protocol and registered fields */
static int proto_c1222 = -1;
@@ -993,7 +994,7 @@

\param tree
*/
static void
-dissect_c1222_full(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+dissect_c1222_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
proto_item      *c1222_item = NULL;
proto_tree     *c1222_tree = NULL;
@@ -1041,7 +1042,7 @@
dissect_c1222(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
tcp_dissect_pdus(tvb, pinfo, tree, c1222_desegment, 5,



      get_c1222_message_len, dissect_c1222_full);





      get_c1222_message_len, dissect_c1222_common);



}
/— proto_register_c1222 ——————————————-/
@@ -1328,7 +1329,9 @@
 if( !initialized ) {
     c1222_handle = create_dissector_handle(dissect_c1222, proto_c1222);



          c1222_udp_handle = create_dissector_handle(dissect_c1222_common,



proto_c1222);
dissector_add_uint("tcp.port", global_c1222_port, c1222_handle);


   dissector_add_uint(&quot;udp.port&quot;, global_c1222_port, c1222_udp_handle);
   initialized = TRUE;

}
}

and regenerate the dissector(run nmake in the asn1/c1222 dir and then in top dir).