Improve Infiniband heuristic subdissection.

Add preference in Infiniband dissector to distinguish between
heuristic and non-heuristic dissection (that uses Decode As).
Remove all of the preferences in the Infiniband subdissectors that
tried to put in "manual" heuristics and direct users to just use
Decode As.  Most subdissectors still kept some basic heuristics in
their heuristic functions, but now also register with the Infiniband
dissector table for "manually" forcing dissection with Decode As.

Ping-Bug: 13259
Change-Id: I20d56eee38887664b439e52ec5f5b8f962c45ef1
Reviewed-on: https://code.wireshark.org/review/19362
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>

1 files changed, 53 insertions, 2 deletions

diff --git a/epan/dissectors/packet-infiniband.c b/epan/dissectors/packet-infiniband.c
index f775864638..70038a8ed4 100644
--- a/epan/dissectors/packet-infiniband.c
+++ b/epan/dissectors/packet-infiniband.c
@@ -31,6 +31,7 @@
 #include <epan/prefs.h>
 #include <epan/etypes.h>
 #include <epan/show_exception.h>
+#include <epan/decode_as.h>
 #include <wiretap/erf.h>
 
 #include "packet-infiniband.h"
@@ -116,6 +117,8 @@ static dissector_handle_t ipv6_handle;
 static dissector_handle_t eth_handle;
 static dissector_table_t ethertype_dissector_table;
 
+static dissector_table_t subdissector_table;
+
 /* MAD_Data
 * Structure to hold information from the common MAD header.
 * This is necessary because the MAD header contains information which significantly changes the dissection algorithm. */
@@ -1504,6 +1507,7 @@ static guint32 opCode_PAYLD[] = {
 
 /* settings to be set by the user via the preferences dialog */
 static guint pref_rroce_udp_port = DEFAULT_RROCE_UDP_PORT;
+static gboolean try_heuristic_first = TRUE;
 
 /* saves information about connections that have been/are in the process of being
    negotiated via ConnectionManagement packets */
@@ -1527,6 +1531,15 @@ static heur_dissector_list_t heur_dissectors_payload;
 static heur_dissector_list_t heur_dissectors_cm_private;
 
 /* ----- This sections contains various utility functions indirectly related to Infiniband dissection ---- */
+static void infiniband_payload_prompt(packet_info *pinfo _U_, gchar* result)
+{
+    g_snprintf(result, MAX_DECODE_AS_PROMPT_LEN, "Dissect Infiniband payload as");
+}
+
+static gpointer infiniband_payload_value(packet_info *pinfo _U_)
+{
+    return 0;
+}
 
 static void table_destroy_notify(gpointer data) {
     g_free(data);
@@ -2410,6 +2423,7 @@ static void parse_PAYLOAD(proto_tree *parentTree,
     tvbuff_t *volatile  next_tvb;
     gint                reported_length;
     heur_dtbl_entry_t  *hdtbl_entry;
+    gboolean            dissector_found = FALSE;
 
     if (!tvb_bytes_exist(tvb, *offset, length)) /* previously consumed bytes + offset was all the data - none or corrupt payload */
     {
@@ -2501,8 +2515,32 @@ static void parse_PAYLOAD(proto_tree *parentTree,
             reported_length -= crclen;
         next_tvb = tvb_new_subset_length(tvb, local_offset, reported_length);
 
-        /* Try any heuristic dissectors that requested a chance to try and dissect IB payloads */
-        if (!dissector_try_heuristic(heur_dissectors_payload, next_tvb, pinfo, top_tree, &hdtbl_entry, info)) {
+        if (try_heuristic_first)
+        {
+            if (dissector_try_heuristic(heur_dissectors_payload, next_tvb, pinfo, top_tree, &hdtbl_entry, info))
+                dissector_found = TRUE;
+        }
+
+        if (dissector_found == FALSE)
+        {
+            /* Functionality for choosing subdissector is controlled through Decode As as there
+               isn't a unique identifier to determine subdissector */
+            if (dissector_try_uint_new(subdissector_table, 0, next_tvb, pinfo, top_tree, TRUE, info))
+            {
+                dissector_found = TRUE;
+            }
+            else
+            {
+                if (!try_heuristic_first)
+                {
+                    if (dissector_try_heuristic(heur_dissectors_payload, next_tvb, pinfo, top_tree, &hdtbl_entry, info))
+                        dissector_found = TRUE;
+                }
+            }
+        }
+
+        if (dissector_found == FALSE)
+        {
             /* No sub-dissector found.
                Label rest of packet as "Data" */
             call_data_dissector(next_tvb, pinfo, top_tree);
@@ -7913,6 +7951,12 @@ void proto_register_infiniband(void)
         &ett_eoib
     };
 
+    /* Decode As handling */
+    static build_valid_func infiniband_payload_da_build_value[1] = {infiniband_payload_value};
+    static decode_as_value_t infiniband_payload_da_values = {infiniband_payload_prompt, 1, infiniband_payload_da_build_value};
+    static decode_as_t infiniband_payload_da = {"infiniband", "Network", "infiniband", 1, 0, &infiniband_payload_da_values, NULL, NULL,
+                                        decode_as_default_populate_list, decode_as_default_reset, decode_as_default_change, NULL};
+
     proto_infiniband = proto_register_protocol("InfiniBand", "IB", "infiniband");
     ib_handle = register_dissector("infiniband", dissect_infiniband, proto_infiniband);
 
@@ -7922,6 +7966,7 @@ void proto_register_infiniband(void)
     /* register the subdissector tables */
     heur_dissectors_payload = register_heur_dissector_list("infiniband.payload", proto_infiniband);
     heur_dissectors_cm_private = register_heur_dissector_list("infiniband.mad.cm.private", proto_infiniband);
+    subdissector_table = register_dissector_table("infiniband", "Infiniband Payload", proto_infiniband, FT_UINT16, BASE_DEC);
 
     /* register dissection preferences */
     infiniband_module = prefs_register_protocol(proto_infiniband, proto_reg_handoff_infiniband);
@@ -7931,6 +7976,10 @@ void proto_register_infiniband(void)
     prefs_register_uint_preference(infiniband_module, "rroce.port", "RRoce UDP Port(Default 1021)", "when set "
                                    "the Analyser will consider this as RRoce UDP Port and parse it accordingly",
                                     10, &pref_rroce_udp_port);
+    prefs_register_bool_preference(infiniband_module, "try_heuristic_first",
+        "Try heuristic sub-dissectors first",
+        "Try to decode a packet using an heuristic sub-dissector before using Decode As",
+        &try_heuristic_first);
 
     proto_infiniband_link = proto_register_protocol("InfiniBand Link", "InfiniBand Link", "infiniband_link");
     ib_link_handle = register_dissector("infiniband_link", dissect_infiniband_link, proto_infiniband_link);
@@ -7945,6 +7994,8 @@ void proto_register_infiniband(void)
     /* initialize the hash table */
     CM_context_table = g_hash_table_new_full(g_int64_hash, g_int64_equal,
                                              table_destroy_notify, table_destroy_notify);
+
+    register_decode_as(&infiniband_payload_da);
 }
 
 /* Reg Handoff.  Register dissectors we'll need for IPoIB and RoCE */