Wireshark · Wireshark-dev: [Wireshark-dev] [RFC-PATCH] IB: Create single conversation for Infiniband connections whenever possi

[Slava Shwartsman <slavash@xxxxxxxxxxxx>]

IB packets do not have source QP in each packet. For that reason
conversations created by infiniband dissector create one conversation
for each direction of the connection. This does not allow dissectors
above IB to be able to fully analyse the protocol such as matching
requests to responses. This behavior can be improved if our capture
includes CM establishment packets that contain both source and
destination QP numbers. The solution is to create a single conversation
and insert it into hash table with the keys that will be looked up by
dissectors. These keys woud be:
1) Source and destination QP and LID/GID
2) Source QP and LID/GID with -1 as destination QP
3) Destination QP and LID/GID with -1 as source QP

All above keys point to the same conversation.

Note that since there is no source, the actual QP number is passed as
destination port along with LID/GID as destination address.

Change-Id: I070e6d246b2c8818b0967b19f2e8548fe2eeeeb0
Signed-off-by: Slava Shwartsman <slavash@xxxxxxxxxxxx>
---
 epan/conversation.c                 | 56 ++++++++++++++++++++++++++++++-------
 epan/dissectors/packet-infiniband.c | 23 +++------------
 2 files changed, 50 insertions(+), 29 deletions(-)

diff --git a/epan/conversation.c b/epan/conversation.c
index 8595551..cc83359 100644
--- a/epan/conversation.c
+++ b/epan/conversation.c
@@ -548,16 +548,52 @@ conversation_init(void)
 static void
 conversation_insert_into_hashtable(GHashTable *hashtable, conversation_t *conv)
 {
-	conversation_t *chain_head, *chain_tail, *cur, *prev;
-
-	chain_head = (conversation_t *)g_hash_table_lookup(hashtable, conv->key_ptr);
-
-	if (NULL==chain_head) {
-		/* New entry */
-		conv->next = NULL;
-		conv->last = conv;
-		g_hash_table_insert(hashtable, conv->key_ptr, conv);
-		DPRINT(("created a new conversation chain"));
+    conversation_t *chain_head, *chain_tail, *cur, *prev;
+    conversation_key *src_qp_key;
+    conversation_key *dst_qp_key;
+
+    chain_head = (conversation_t *)g_hash_table_lookup(hashtable, conv->key_ptr);
+
+    if (NULL==chain_head) {
+        /* New entry */
+        conv->next = NULL;
+        conv->last = conv;
+        DPRINT(("created a new conversation chain"));
+        if (!((hashtable == conversation_hashtable_exact)
+                && (conv->key_ptr->ptype == PT_IBQP)))
+        	g_hash_table_insert(hashtable, conv->key_ptr, conv);
+        /*
+         * IB packets do not have source QP in each packet. For that reason
+         * conversations created by Infiniband dissector create one conversation
+         * for each direction of the connection. This does not allow dissectors
+         * above IB to be able to fully analyze the protocol such as matching
+         * requests to responses. This behavior can be improved if our capture
+         * includes CM establishment packets that contain both source and
+         * destination QP numbers. The solution is to create a single conversation
+         * and insert it into hash table with the keys that will be looked up by
+         * dissectors.
+         */
+        else {
+        	src_qp_key = wmem_new(wmem_file_scope(), struct conversation_key);
+        	src_qp_key->next = conversation_keys;
+            conversation_keys = src_qp_key;
+            src_qp_key->addr1 = conv->key_ptr->addr1;
+            src_qp_key->addr2 = conv->key_ptr->addr2;
+            src_qp_key->ptype = conv->key_ptr->ptype;
+            src_qp_key->port1 = 0xffffffff;
+            src_qp_key->port2 = conv->key_ptr->port2;
+            g_hash_table_insert(hashtable, src_qp_key, conv);
+
+            dst_qp_key = wmem_new(wmem_file_scope(), struct conversation_key);
+            dst_qp_key->next = conversation_keys;
+            conversation_keys = dst_qp_key;
+            dst_qp_key->addr1 = conv->key_ptr->addr2;
+            dst_qp_key->addr2 = conv->key_ptr->addr1;
+            dst_qp_key->ptype = conv->key_ptr->ptype;
+            dst_qp_key->port1 = 0xffffffff;
+            dst_qp_key->port2 = conv->key_ptr->port1;
+            g_hash_table_insert(hashtable, dst_qp_key, conv);
+		}
 	}
 	else {
 		/* There's an existing chain for this key */
diff --git a/epan/dissectors/packet-infiniband.c b/epan/dissectors/packet-infiniband.c
index 33fe8ea..9b0b5dd 100644
--- a/epan/dissectors/packet-infiniband.c
+++ b/epan/dissectors/packet-infiniband.c
@@ -1703,7 +1703,6 @@ skip_lrh:
                 dctBthHeader = TRUE;
                 bthSize += 8;
             }
-
             base_transport_header_item = proto_tree_add_item(all_headers_tree, hf_infiniband_BTH, tvb, offset, bthSize, ENC_NA);
             proto_item_set_text(base_transport_header_item, "%s", "Base Transport Header");
             base_transport_header_tree = proto_item_add_subtree(base_transport_header_item, ett_bth);
@@ -3098,33 +3097,20 @@ static void parse_COM_MGT(proto_tree *parentTree, packet_info *pinfo, tvbuff_t *
                     proto_data = wmem_new(wmem_file_scope(), conversation_infiniband_data);
                     proto_data->service_id = connection->service_id;
 
-                    /* RC traffic never(?) includes a field indicating the source QPN, so
-                       the destination host knows it only from previous context (a single
-                       QPN on the host that is part of an RC can only receive traffic from
-                       that RC). For this reason we do not register conversations with both
-                       sides, but rather we register the same conversation twice - once for
-                       each side of the Reliable Connection. */
-
                     /* first register the conversation using the GIDs */
                     SET_ADDRESS(&req_addr, AT_IB, GID_SIZE, connection->req_gid);
                     SET_ADDRESS(&resp_addr, AT_IB, GID_SIZE, connection->resp_gid);
 
-                    conv = conversation_new(pinfo->fd->num, &req_addr, &req_addr,
-                                            PT_IBQP, connection->req_qp, connection->req_qp, NO_ADDR2|NO_PORT2);
-                    conversation_add_proto_data(conv, proto_infiniband, proto_data);
-                    conv = conversation_new(pinfo->fd->num, &resp_addr, &resp_addr,
-                                            PT_IBQP, connection->resp_qp, connection->resp_qp, NO_ADDR2|NO_PORT2);
+                    conv = conversation_new(pinfo->fd->num, &resp_addr,&req_addr,
+                        PT_IBQP, connection->resp_qp, connection->req_qp,  0);
                     conversation_add_proto_data(conv, proto_infiniband, proto_data);
 
                     /* next, register the conversation using the LIDs */
                     SET_ADDRESS(&req_addr, AT_IB, sizeof(guint16), &(connection->req_lid));
                     SET_ADDRESS(&resp_addr, AT_IB, sizeof(guint16), &(connection->resp_lid));
 
-                    conv = conversation_new(pinfo->fd->num, &req_addr, &req_addr,
-                                            PT_IBQP, connection->req_qp, connection->req_qp, NO_ADDR2|NO_PORT2);
-                    conversation_add_proto_data(conv, proto_infiniband, proto_data);
-                    conv = conversation_new(pinfo->fd->num, &resp_addr, &resp_addr,
-                                            PT_IBQP, connection->resp_qp, connection->resp_qp, NO_ADDR2|NO_PORT2);
+                    conv = conversation_new(pinfo->fd->num, &resp_addr, &req_addr,
+                        PT_IBQP, connection->resp_qp, connection->req_qp,  0);
                     conversation_add_proto_data(conv, proto_infiniband, proto_data);
 
                     g_hash_table_remove(CM_context_table, &hash_key);
@@ -3162,7 +3148,6 @@ static void parse_COM_MGT(proto_tree *parentTree, packet_info *pinfo, tvbuff_t *
             proto_item_append_text(CM_header_item, " (Dissector Not Implemented)"); local_offset += MAD_DATA_SIZE;
             break;
     }
-
     *offset = local_offset;
 }
 
-- 
1.8.3.1