Working implementation

Author: MayamaTakeshi

modules/tm/README

@@ -72,6 +72,7 @@ tm Module
 
               1.4.21. t_flush_flags()
               1.4.22. t_anycast_replicate()
+              1.4.23  t_reply_by_callid()
 
         1.5. Exported Pseudo-Variables
 
@@ -173,6 +174,7 @@ tm Module
    1.42. t_write_req/unix usage
    1.43. t_flush_flags usage
    1.44. t_anycast_replicate usage
+   1.45. t_reply_by_callid usage
 
 Chapter 1. Admin Guide
 
@@ -1372,6 +1374,58 @@ if (is_method("ACK|CANCEL") && !t_check_trans()) {
 }
 ...
 
+1.4.23. t_reply_by_callid(code, reason_phrase, [callid], [cseq])
+
+   This function is used to send a reply to
+   an existing INVITE transaction.
+   The usual use case is when opensips is used as an UAS
+   and when an INVITE is receveid, it is "parked" locally on
+   opensips by replying to it with
+   t_reply(180, "Ringing" or t_reply(183, "Session Progress")
+   and later we need to handle CANCEL or BYE for it and send
+   '487 Request Terminated' to the original INVITE transaction.
+
+   The callid and cseq used to identify the transaction
+   will be obtained from the current messsage being processed.
+   But they can be passed explicitly so that for example we can
+   handle a BYE where the cseq must be the cseq
+   of the INVITE minus one.
+
+   This function can be used from REQUEST_ROUTE.
+
+   Example 1.45. t_reply_by_callid usage
+...
+
+route{
+	if($rU == "LOCAL_PARK") {
+		if(is_method("INVITE")) {
+			$T_fr_timeout = 10;
+			$T_fr_inv_timeout = 10;
+			append_to_reply("Contact: sip:LOCAL_PARK@$socket_in(ip):$socket_in(port)\r\n");
+			t_reply(180, "Ringing");
+			t_wait_for_new_branches();
+		} else if(is_method("CANCEL")) {
+			if(!t_reply_by_callid(487, "Request Terminated")) {
+				sl_send_reply(481, "Call Leg/Transaction Does Not Exist");
+			} else {
+				sl_send_reply(200, "OK");
+			}
+		} else if(is_method("BYE")) {
+			$var(prev_cseq) = ($(cs{s.int}) - 1);
+			if(!t_reply_by_callid(487, "Request Terminated", , $var(prev_cseq))) {
+				sl_send_reply(481, "Call Leg/Transaction Does Not Exist");
+			} else {
+				sl_send_reply(200, "OK");
+			}
+		} else if(is_method("ACK")) {
+			t_relay();
+		}
+		exit;
+	}
+}
+
+...
+
 1.5. Exported Pseudo-Variables
 
    Exported variables are listed in the next sections.

modules/tm/tm.c

@@ -128,6 +128,7 @@ static int w_t_new_request(struct sip_msg* msg, str *method,
 static int t_wait_for_new_branches(struct sip_msg* msg,
 			unsigned int* br_to_wait);
 static int w_t_wait_no_more_branches(struct sip_msg* msg);
+static int t_reply_by_callid(struct sip_msg* msg, unsigned int* code, str* text, str* callid, str* cseq);
 
 struct sip_msg* tm_pv_context_request(struct sip_msg* msg);
 struct sip_msg* tm_pv_context_reply(struct sip_msg* msg);
@@ -272,6 +273,12 @@ static cmd_export_t cmds[]={
 		REQUEST_ROUTE|ONREPLY_ROUTE|BRANCH_ROUTE|FAILURE_ROUTE},
 	{"t_anycast_replicate", (cmd_function)tm_anycast_replicate, {{0,0,0}},
 		REQUEST_ROUTE},
+	{"t_reply_by_callid", (cmd_function)t_reply_by_callid, {
+		{CMD_PARAM_INT, fixup_reply_code, 0},
+		{CMD_PARAM_STR, 0, 0},
+		{CMD_PARAM_STR | CMD_PARAM_OPT, 0, 0},
+		{CMD_PARAM_STR | CMD_PARAM_OPT, 0, 0}, {0,0,0}},
+		REQUEST_ROUTE},
 	{"load_tm", (cmd_function)load_tm, {{0,0,0}}, 0},
 	{0,0,{{0,0,0}},0}
 };
@@ -1609,6 +1616,33 @@ static int w_t_wait_no_more_branches(struct sip_msg* msg)
 	return 1;
 }
 
+
+static int t_reply_by_callid(struct sip_msg* msg, unsigned int* code, str* text, str* callid, str* cseq_number)
+{
+	struct cell *trans;
+	int n;
+
+	if (!callid && msg->callid==NULL && ((parse_headers(msg, HDR_CALLID_F, 0) ==-1) || (msg->callid==NULL)) ) {
+		/* could not get callid */
+		return -2;
+	}
+
+	if (!cseq_number && !msg->cseq && ((parse_headers(msg, HDR_CSEQ_F, 0) == -1) || !msg->cseq)) {
+		/* could not get cseq */
+		return -3;
+	}
+
+	if(t_lookup_callid( &trans, callid ? *callid : msg->callid->body, cseq_number ? *cseq_number : get_cseq(msg)->number) < 0) {
+		/* transaction not found */
+		return -4;
+	}
+
+	n = t_reply_with_body( trans, *code, text, 0, 0, 0);
+
+	return n;
+}
+
+
 /******************** pseudo-variable functions *************************/
 
 static int pv_get_tm_branch_idx(struct sip_msg *msg, pv_param_t *param,