RTPS: don't use incompletely filled in GUIDs.

Add to the GUID type a bitmask that indicates which fields have been
filled in; start it out as 0, and then set bits in it as fields get
filled in.

Do not add a type mapping object to the hash table unless the GUID is
completely filled in, and don't look for a type mapping object in the
hash table with a GUID that hasn't been completely filled in as a key.

Bug: 16642
Change-Id: I31db92238adcb2ec2d70b2650e41b14d99001908
Reviewed-on: https://code.wireshark.org/review/37537
Petri-Dish: Guy Harris <gharris@sonic.net>
Tested-by: Petri Dish Buildbot
Reviewed-by: Guy Harris <gharris@sonic.net>

1 files changed, 35 insertions, 2 deletions

diff --git a/epan/dissectors/packet-rtps.c b/epan/dissectors/packet-rtps.c
index 0a1f964dc6..fbe9f8784c 100644
--- a/epan/dissectors/packet-rtps.c
+++ b/epan/dissectors/packet-rtps.c
@@ -1643,7 +1643,17 @@ static int* const ENDPOINT_SECURITY_ATTRIBUTES[] = {
   NULL
 };
 
+/*
+ * Flags indicating which fields have been filled in.
+ */
+#define GUID_HAS_HOST_ID     0x00000001
+#define GUID_HAS_APP_ID      0x00000002
+#define GUID_HAS_INSTANCE_ID 0x00000004
+#define GUID_HAS_ENTITY_ID   0x00000008
+#define GUID_HAS_ALL         0x0000000F
+
 typedef struct _endpoint_guid {
+  guint   fields_present;
   guint32 host_id;
   guint32 app_id;
   guint32 instance_id;
@@ -4411,6 +4421,7 @@ static int rtps_util_add_fragment_number_set(proto_tree *tree, packet_info *pinf
 static void rtps_util_insert_type_mapping_in_registry(packet_info *pinfo, type_mapping *type_mapping_object) {
   if (type_mapping_object) {
     if ((type_mapping_object->fields_visited & TOPIC_INFO_ALL_SET) == TOPIC_INFO_ALL_SET &&
+              type_mapping_object->guid.fields_present == GUID_HAS_ALL &&
               !wmem_map_lookup(registry, &(type_mapping_object->guid))) {
         if (((type_mapping_object->guid.entity_id & 0x02) == 0x02) || ((type_mapping_object->guid.entity_id & 0x04) == 0x04)){
           /* If it is an application defined writer matches 0x02. Matches 0x04 if it is an application defined reader */
@@ -4430,6 +4441,8 @@ static void rtps_util_store_type_mapping(packet_info *pinfo _U_, tvbuff_t *tvb,
           type_mapping_object->guid.app_id = tvb_get_ntohl(tvb, offset+4);
           type_mapping_object->guid.instance_id = tvb_get_ntohl(tvb, offset+8);
           type_mapping_object->guid.entity_id = tvb_get_ntohl(tvb, offset+12);
+          type_mapping_object->guid.fields_present |=
+                  GUID_HAS_HOST_ID|GUID_HAS_HOST_ID|GUID_HAS_INSTANCE_ID|GUID_HAS_ENTITY_ID;
           type_mapping_object->fields_visited =
                   type_mapping_object->fields_visited | TOPIC_INFO_ADD_GUID;
           break;
@@ -4455,6 +4468,7 @@ static void rtps_util_store_type_mapping(packet_info *pinfo _U_, tvbuff_t *tvb,
 
 static guint hash_by_guid(gconstpointer key) {
   const endpoint_guid * guid = (const endpoint_guid *) key;
+  DISSECTOR_ASSERT(guid->fields_present & GUID_HAS_APP_ID);
   return g_int_hash(&(guid->app_id));
 }
 
@@ -4489,8 +4503,10 @@ static gboolean compare_by_coherent_set_key(gconstpointer a, gconstpointer b) {
 static type_mapping * rtps_util_get_topic_info(endpoint_guid * guid) {
   /* At this point, we know the boolean enable_topic_info is true */
   type_mapping * result = NULL;
-  if (guid)
-    result = (type_mapping *)wmem_map_lookup(registry, guid);
+  if (guid) {
+    if (guid->fields_present == GUID_HAS_ALL)
+      result = (type_mapping *)wmem_map_lookup(registry, guid);
+  }
   return result;
 }
 
@@ -4507,6 +4523,7 @@ static void rtps_util_format_typename(gchar * type_name, gchar ** output) {
 
 static void rtps_util_topic_info_add_tree(proto_tree *tree, tvbuff_t *tvb,
   gint offset, endpoint_guid * guid) {
+  /* Do not search unless the GUID is completely filled in */
   if (enable_topic_info) {
     proto_tree * topic_info_tree;
     proto_item * ti;
@@ -6724,6 +6741,7 @@ static gint dissect_parameter_sequence(proto_tree *tree, packet_info *pinfo, tvb
      */
     type_mapping_object = wmem_new(wmem_file_scope(), type_mapping);
     type_mapping_object->fields_visited = 0;
+    type_mapping_object->guid.fields_present = 0;
   }
 
   rtps_parameter_sequence_tree = proto_tree_add_subtree_format(tree, tvb, offset, size,
@@ -8140,6 +8158,7 @@ static void dissect_ACKNACK(tvbuff_t *tvb, packet_info *pinfo, gint offset, guin
                         hf_rtps_sm_wrentity_id_kind, ett_rtps_wrentity, "writerEntityId", &wid);
   offset += 4;
   guid->entity_id = wid;
+  guid->fields_present |= GUID_HAS_ENTITY_ID;
   rtps_util_topic_info_add_tree(tree, tvb, offset, guid);
 
   /* Bitmap */
@@ -8312,6 +8331,7 @@ static void dissect_HEARTBEAT(tvbuff_t *tvb, packet_info *pinfo, gint offset, gu
                         hf_rtps_sm_wrentity_id_kind, ett_rtps_wrentity, "writerEntityId", &wid);
   offset += 4;
   guid->entity_id = wid;
+  guid->fields_present |= GUID_HAS_ENTITY_ID;
   rtps_util_topic_info_add_tree(tree, tvb, offset, guid);
 
   /* First available Sequence Number */
@@ -8391,6 +8411,7 @@ static void dissect_HEARTBEAT_BATCH(tvbuff_t *tvb, packet_info *pinfo, gint offs
                         hf_rtps_sm_wrentity_id_kind, ett_rtps_wrentity, "writerEntityId", &wid);
   offset += 4;
   guid->entity_id = wid;
+  guid->fields_present |= GUID_HAS_ENTITY_ID;
   rtps_util_topic_info_add_tree(tree, tvb, offset, guid);
 
   /* First available Batch Sequence Number */
@@ -8532,6 +8553,7 @@ static void dissect_HEARTBEAT_VIRTUAL(tvbuff_t *tvb, packet_info *pinfo _U_, gin
     writer_id_offset = offset;
     offset += 4;
     guid->entity_id = wid;
+    guid->fields_present |= GUID_HAS_ENTITY_ID;
     rtps_util_topic_info_add_tree(tree, tvb, offset, guid);
 
     /* virtualGUID */
@@ -8733,6 +8755,7 @@ static void dissect_HEARTBEAT_FRAG(tvbuff_t *tvb, packet_info *pinfo, gint offse
                         hf_rtps_sm_wrentity_id_kind, ett_rtps_wrentity, "writerEntityId", &wid);
   offset += 4;
   guid->entity_id = wid;
+  guid->fields_present |= GUID_HAS_ENTITY_ID;
   rtps_util_topic_info_add_tree(tree, tvb, offset, guid);
 
   /* First available Sequence Number */
@@ -8854,6 +8877,7 @@ static void dissect_RTPS_DATA(tvbuff_t *tvb, packet_info *pinfo, gint offset, gu
                         hf_rtps_sm_wrentity_id_kind, ett_rtps_wrentity, "writerEntityId", &wid);
   offset += 4;
   guid->entity_id = wid;
+  guid->fields_present |= GUID_HAS_ENTITY_ID;
   rtps_util_topic_info_add_tree(tree, tvb, offset, guid);
 
   /* Sequence number */
@@ -9188,6 +9212,7 @@ static void dissect_RTPS_DATA_FRAG(tvbuff_t *tvb, packet_info *pinfo, gint offse
                         hf_rtps_sm_wrentity_id_kind, ett_rtps_wrentity, "writerEntityId", &wid);
   offset += 4;
   guid->entity_id = wid;
+  guid->fields_present |= GUID_HAS_ENTITY_ID;
   rtps_util_topic_info_add_tree(tree, tvb, offset, guid);
 
 
@@ -9421,6 +9446,7 @@ static void dissect_RTPS_DATA_BATCH(tvbuff_t *tvb, packet_info *pinfo, gint offs
                         hf_rtps_sm_wrentity_id_kind, ett_rtps_wrentity, "writerEntityId", &wid);
   offset += 4;
   guid->entity_id = wid;
+  guid->fields_present |= GUID_HAS_ENTITY_ID;
   rtps_util_topic_info_add_tree(tree, tvb, offset, guid);
 
 
@@ -9663,6 +9689,7 @@ static void dissect_GAP(tvbuff_t *tvb, packet_info *pinfo, gint offset,
                         ett_rtps_wrentity, "writerEntityId", &wid);
   offset += 4;
   guid->entity_id = wid;
+  guid->fields_present |= GUID_HAS_ENTITY_ID;
   rtps_util_topic_info_add_tree(tree, tvb, offset, guid);
 
 
@@ -9946,6 +9973,7 @@ static void dissect_INFO_DST(tvbuff_t *tvb, packet_info *pinfo, gint offset, gui
       dst_guid->host_id = tvb_get_ntohl(tvb, offset);
       dst_guid->app_id = tvb_get_ntohl(tvb, offset + 4);
       dst_guid->instance_id = tvb_get_ntohl(tvb, offset + 8);
+      dst_guid->fields_present |= GUID_HAS_HOST_ID|GUID_HAS_APP_ID|GUID_HAS_INSTANCE_ID;
   }
 }
 
@@ -10367,6 +10395,10 @@ static gboolean dissect_rtps(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree
   if ((majorRev != 1) && (majorRev != 2))
     return FALSE;
 
+  /* No fields have been set in either GUID yet. */
+  guid.fields_present = 0;
+  dst_guid.fields_present = 0;
+
   col_set_str(pinfo->cinfo, COL_PROTOCOL, "RTPS");
   col_clear(pinfo->cinfo, COL_INFO);
 
@@ -10397,6 +10429,7 @@ static gboolean dissect_rtps(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree
     guid.host_id = tvb_get_ntohl(tvb, offset+8);
     guid.app_id = tvb_get_ntohl(tvb, offset+12);
     guid.instance_id = tvb_get_ntohl(tvb, offset+16);
+    guid.fields_present |= GUID_HAS_HOST_ID|GUID_HAS_APP_ID|GUID_HAS_INSTANCE_ID;
 #ifdef RTI_BUILD
     pinfo->guid_prefix_host = tvb_get_ntohl(tvb, offset + 8);
     pinfo->guid_prefix_app  = tvb_get_ntohl(tvb, offset + 12);