[siptrace] allow other modules to trace messages

	A new api in siptrace module has been defined which allows
tracing messages using any implemented trace protocol(currently
only hep) in sip context(per message/transaction/dialog). This
way tracing messages other than sip(log messages, rest, http)
will be much easier to implement.
	Along with the new api, sip_trace function has been extended
to accept another extra parameter which will specify the types of
messages to be traced(by default only sip messages shall be traced).
Modules that will implement the api have to register to siptrace
module using an identifier which will be used by sip_trace function
in order to identify the types of tracing that are enabled.
	Also initial trace api has been modified. After sending,
the traced message won't be freed, leaving this posibility to the
user.

modules/proto_hep/hep.c

@@ -1130,7 +1130,6 @@ static char* build_hep12_buf(struct hep_desc* hep_msg, int* len)
 	}
 
 	memcpy(buf+p, hep_msg->u.hepv12.payload.s, hep_msg->u.hepv12.payload.len);
-	pkg_free(hep_msg);
 
 	*len = buflen;
 
@@ -1154,7 +1153,7 @@ static char* build_hep3_buf(struct hep_desc* hep_msg, int* len)
 	int rem, hdr_len, pld_len;
 	char* buf;
 
-	generic_chunk_t *it, *foo;
+	generic_chunk_t *it;
 
 	*len = 0;
 
@@ -1202,11 +1201,7 @@ static char* build_hep3_buf(struct hep_desc* hep_msg, int* len)
 
 
 
-	foo = NULL;
-	for (it=hep_msg->u.hepv3.chunk_list; it; foo=it, it=it->next) {
-		if (foo)
-			pkg_free(foo);
-
+	for (it=hep_msg->u.hepv3.chunk_list; it; it=it->next) {
 		hdr_len = it->chunk.length;
 
 		it->chunk.vendor_id = htons(it->chunk.vendor_id);
@@ -1220,11 +1215,6 @@ static char* build_hep3_buf(struct hep_desc* hep_msg, int* len)
 		UPDATE_CHECK_REMAINING(rem, *len, hdr_len - sizeof(hep_chunk_t));
 	}
 
-	if (foo)
-		pkg_free(foo);
-
-	pkg_free(hep_msg);
-
 	if (rem) {
 		LM_ERR("%d bytes not copied!\n", rem);
 		return NULL;
@@ -1249,23 +1239,25 @@ static char* build_hep3_buf(struct hep_desc* hep_msg, int* len)
  * create message function
  * */
 trace_message create_hep_message(union sockaddr_union* from_su, union sockaddr_union* to_su,
-		int net_proto, str* payload, int pld_proto, int version)
+		int net_proto, str* payload, int pld_proto, trace_dest dest)
 {
+	hid_list_p hep_dest = (hid_list_p) dest;
+
 	if (from_su == NULL || to_su == NULL || payload == NULL ||
 								payload->s == NULL || payload->len == 0) {
 		LM_ERR("invalid call! bad input params!\n");
 		return NULL;
 	}
 
-	switch (version) {
+	switch (hep_dest->version) {
 		case 1:
 		case 2:
-			return create_hep12_message(from_su, to_su, net_proto, payload, version);
+			return create_hep12_message(from_su, to_su, net_proto, payload, hep_dest->version);
 		case 3:
 			return create_hep3_message(from_su, to_su, net_proto, payload, pld_proto);
 	}
 
-	LM_ERR("invalid hep protocol version [%d]!", version);
+	LM_ERR("invalid hep protocol version [%d]!", hep_dest->version);
 	return NULL;
 }
 
@@ -1355,12 +1347,13 @@ int send_hep_message(trace_message message, trace_dest dest, struct socket_info*
 	struct proxy_l* p;
 	union sockaddr_union* to;
 
+	hid_list_p hep_dest = (hid_list_p) dest;
+
 	if (message == NULL || dest == NULL) {
 		LM_ERR("invalid call! bad input params!\n");
 		return -1;
 	}
 
-	hid_list_p hep_dest = (hid_list_p) dest;
 
 	if (((struct hep_desc *)message)->version == 3) {
 		/* hep msg will be freed after */