f5ethtrailer: type-version subdissector table

Add a subdissector table to the noise provider.
This allows for extendability via a plugin to support
new versions or message types of trailer noise.

The original f5ethtrailer was distrubuted as a plugin.
Since including it as part of libwireshark it has been
impossible to add support for changes in the data this
dissector decodes once Wireshark is released without patching
and compiling on your own (or possibly building a git dev branch).

This provides a mechanisim to add additional support to the
dissector via plugin without needing to rebuild Wireshark.

Change-Id: I1912ab497e0cfd34dcd92a893b819333665e23cd
Reviewed-on: https://code.wireshark.org/review/34063
Petri-Dish: Anders Broman <a.broman58@gmail.com>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

diff --git a/epan/dissectors/packet-f5ethtrailer.c b/epan/dissectors/packet-f5ethtrailer.c
index 7471cded648468e18b2b6b3c57301d05bfde632d..95baaac296b148f58ce22b6ccd207bbbfb059946 100644 (file)
--- a/epan/dissectors/packet-f5ethtrailer.c
+++ b/epan/dissectors/packet-f5ethtrailer.c
@@ -384,6 +384,7 @@ static const int *hf_flags__fields[] = {
 
 /** Table containing subdissectors for different providers */
 static dissector_table_t provider_subdissector_table;
+static dissector_table_t noise_subdissector_table;
 
 
 /*-----------------------------------------------------------------------------------------------*/
@@ -2134,6 +2135,7 @@ dissect_dpt_trailer_noise_high(
        render_f5dptv1_tlvhdr(tvb, tree, 0);
 
        o = F5_DPT_V1_TLV_HDR_LEN;
+       tdata->noise_high = 1;
 
        /* If there was no peer id in the medium trailer, then there is no peer flow information to
         * render; skip it all.
@@ -2265,6 +2267,7 @@ dissect_dpt_trailer_noise_med(
        render_f5dptv1_tlvhdr(tvb, tree, 0);
 
        o = F5_DPT_V1_TLV_HDR_LEN;
+       tdata->noise_med = 1;
        rstcauselen = F5TRL_MEDV4_RSTCLEN(tvb,o);
        /* Check for an invalid reset cause length and do not try to reference any of the data if it is
         * bad
@@ -2421,6 +2424,7 @@ dissect_dpt_trailer_noise_low(
        render_f5dptv1_tlvhdr(tvb, tree, 0);
 
        o = F5_DPT_V1_TLV_HDR_LEN;
+       tdata->noise_low = 1;
 
        /* Direction */
        flags = tvb_get_guint8(tvb, o);
@@ -2515,32 +2519,9 @@ dissect_dpt_trailer_noise(
        proto_tree *tree,
        void *data
 ) {
-       f5eth_tap_data_t   *tdata = (f5eth_tap_data_t *)data;
-       int                 processed;
-
-       switch(tvb_get_ntohs(tvb, F5_DPT_V1_TLV_TYPE_OFF)) {
-               case F5TYPE_LOW:
-                       processed = dissect_dpt_trailer_noise_low(tvb, pinfo, tree, data);
-                       if(processed > 0) {
-                               tdata->noise_low = 1;
-                       }
-                       break;
-               case F5TYPE_MED:
-                       processed = dissect_dpt_trailer_noise_med(tvb, pinfo, tree, data);
-                       if(processed > 0)
-                               tdata->noise_med = 1;
-                       break;
-               case F5TYPE_HIGH:
-                       processed = dissect_dpt_trailer_noise_high(tvb, pinfo, tree, data);
-                       if(processed > 0)
-                               tdata->noise_high = 1;
-                       break;
-               default:
-                       /* Skip unknown TLV types */
-                       processed = 0;
-                       break;
-       }
-       return(processed);
+       guint32 pattern;
+       pattern = tvb_get_ntohs(tvb, F5_DPT_V1_TLV_TYPE_OFF) << 16 | tvb_get_ntohs(tvb, F5_DPT_V1_TLV_VERSION_OFF);
+       return(dissector_try_uint_new(noise_subdissector_table, pattern,tvb, pinfo, tree, FALSE, data));
 } /* dissect_dpt_trailer_noise() */
 
 
@@ -3285,6 +3266,7 @@ void proto_register_f5ethtrailer (void)
        proto_f5ethtrailer_dpt_noise = proto_register_protocol_in_name_only(
                        "F5 Ethernet trailer provider - Noise", "Noise", "f5ethtrailer.provider.noise",
                        proto_f5ethtrailer, FT_BYTES);
+       noise_subdissector_table = register_dissector_table("f5ethtrailer.noise_type_ver", "F5 Ethernet Trailer Noise", proto_f5ethtrailer, FT_UINT16, BASE_DEC);
 
        /* Analyze Menu Items */
        register_conversation_filter("f5ethtrailer", "F5 TCP", f5_tcp_conv_valid, f5_tcp_conv_filter);
@@ -3315,6 +3297,10 @@ void proto_reg_handoff_f5ethtrailer(void)
        /* Register helper dissectors */
        h = create_dissector_handle(dissect_dpt_trailer_noise, proto_f5ethtrailer_dpt_noise);
        dissector_add_uint("f5ethtrailer.provider", F5_DPT_PROVIDER_NOISE, h);
+       dissector_add_uint("f5ethtrailer.noise_type_ver", F5TYPE_LOW << 16 | 2, create_dissector_handle(dissect_dpt_trailer_noise_low, -1));
+       dissector_add_uint("f5ethtrailer.noise_type_ver", F5TYPE_LOW << 16 | 3, create_dissector_handle(dissect_dpt_trailer_noise_low, -1));
+       dissector_add_uint("f5ethtrailer.noise_type_ver", F5TYPE_MED << 16 | 4, create_dissector_handle(dissect_dpt_trailer_noise_med, -1));
+       dissector_add_uint("f5ethtrailer.noise_type_ver", F5TYPE_HIGH << 16 | 1, create_dissector_handle(dissect_dpt_trailer_noise_high, -1));
 #ifdef F5_POP_OTHERFIELDS
        /* These fields are duplicates of other, well-known fields so that
         * filtering on these fields will also pick up data out of the