Add find_conversation_pinfo

Convenience function to add the same parameters to find_conversation as
find_or_create_conversation.

Change-Id: I3a92541cb9c1e827a9de8248825636debbd989cd
Reviewed-on: https://code.wireshark.org/review/24118
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot
Reviewed-by: Michael Mann <mmann78@netscape.net>

debian/libwireshark0.symbols

@@ -594,6 +594,7 @@ libwireshark.so.0 libwireshark0 #MINVER#
  find_capture_dissector@Base 2.3.0
  find_circuit@Base 1.9.1
  find_conversation@Base 1.9.1
+ find_conversation_pinfo@Base 2.5.0
  find_conversation_filter@Base 2.0.0
  find_depend_dissector_list@Base 2.1.0
  find_dissector@Base 1.9.1

doc/README.dissector

@@ -2578,10 +2578,24 @@ NO_ADDR_B|NO_PORT_B, the "addr_b" address will be treated as matching
 any "wildcarded" address and the "port_b" port will be treated as
 matching any "wildcarded" port.
 
+2.2.1.4 The find_conversation_pinfo function.
 
-2.2.1.4 The find_or_create_conversation function.
+This convenience function will find an existing conversation (by calling
+find_conversation())
 
-This convenience function will create find an existing conversation (by calling
+The find_conversation_pinfo prototype:
+
+    extern conversation_t *find_conversation_pinfo(packet_info *pinfo);
+
+Where:
+    packet_info *pinfo = the packet_info structure
+
+The frame number and the addresses necessary for find_conversation() are
+taken from the pinfo structure (as is commonly done).
+
+2.2.1.5 The find_or_create_conversation function.
+
+This convenience function will find an existing conversation (by calling
 find_conversation()) and, if a conversation does not already exist, create a
 new conversation by calling conversation_new().
 
@@ -2597,7 +2611,7 @@ conversation_new() are taken from the pinfo structure (as is commonly done)
 and no 'options' are used.
 
 
-2.2.1.5 The conversation_add_proto_data function.
+2.2.1.6 The conversation_add_proto_data function.
 
 Once you have created a conversation with conversation_new, you can
 associate data with it using this function.
@@ -2623,7 +2637,7 @@ Using the protocol number allows several dissectors to
 associate data with a given conversation.
 
 
-2.2.1.6 The conversation_get_proto_data function.
+2.2.1.7 The conversation_get_proto_data function.
 
 After you have located a conversation with find_conversation, you can use
 this function to retrieve any data associated with it.
@@ -2642,7 +2656,7 @@ typically in the proto_register_XXXX portion of a dissector.  The function
 returns a pointer to the data requested, or NULL if no data was found.
 
 
-2.2.1.7 The conversation_delete_proto_data function.
+2.2.1.8 The conversation_delete_proto_data function.
 
 After you are finished with a conversation, you can remove your association
 with this function.  Please note that ONLY the conversation entry is
@@ -2661,7 +2675,7 @@ Where:
 is a unique protocol number created with proto_register_protocol,
 typically in the proto_register_XXXX portion of a dissector.
 
-2.2.1.8 The conversation_set_dissector function
+2.2.1.9 The conversation_set_dissector function
 
 This function sets the protocol dissector to be invoked whenever
 conversation parameters (addresses, port_types, ports, etc) are matched

epan/conversation.c

@@ -1231,6 +1231,33 @@ try_conversation_dissector(const address *addr_a, const address *addr_b, const p
 	return FALSE;
 }
 
+/**  A helper function that calls find_conversation() using data from pinfo
+ *  The frame number and addresses are taken from pinfo.
+ */
+conversation_t *
+find_conversation_pinfo(packet_info *pinfo, const guint options)
+{
+	conversation_t *conv=NULL;
+
+	DPRINT(("called for frame #%d: %s:%d -> %s:%d (ptype=%d)",
+		pinfo->num, address_to_str(wmem_packet_scope(), &pinfo->src), pinfo->srcport,
+		address_to_str(wmem_packet_scope(), &pinfo->dst), pinfo->destport, pinfo->ptype));
+	DINDENT();
+
+	/* Have we seen this conversation before? */
+	if((conv = find_conversation(pinfo->num, &pinfo->src, &pinfo->dst,
+				     pinfo->ptype, pinfo->srcport,
+				     pinfo->destport, options)) != NULL) {
+		DPRINT(("found previous conversation for frame #%d (last_frame=%d)",
+				pinfo->num, conv->last_frame));
+		if (pinfo->num > conv->last_frame) {
+			conv->last_frame = pinfo->num;
+		}
+	}
+
+	return conv;
+}
+
 /*  A helper function that calls find_conversation() and, if a conversation is
  *  not found, calls conversation_new().
  *  The frame number and addresses are taken from pinfo.

epan/conversation.h

@@ -145,6 +145,11 @@ WS_DLL_PUBLIC conversation_t *conversation_new(const guint32 setup_frame, const
 WS_DLL_PUBLIC conversation_t *find_conversation(const guint32 frame_num, const address *addr_a, const address *addr_b,
     const port_type ptype, const guint32 port_a, const guint32 port_b, const guint options);
 
+/**  A helper function that calls find_conversation() using data from pinfo
+ *  The frame number and addresses are taken from pinfo.
+ */
+WS_DLL_PUBLIC conversation_t *find_conversation_pinfo(packet_info *pinfo, const guint options);
+
 /**  A helper function that calls find_conversation() and, if a conversation is
  *  not found, calls conversation_new().
  *  The frame number and addresses are taken from pinfo.