[nat] Make the refusal more complicated to support more MSCs

We will need to confirm the connection, then we can send the
GSM48 message, then we need to close the connection... the
embedding in the refusal method was way too easy..

openbsc/include/openbsc/bsc_nat.h

@@ -47,6 +47,7 @@ enum {
 	NAT_CON_TYPE_LU,
 	NAT_CON_TYPE_CM_SERV_REQ,
 	NAT_CON_TYPE_PAG_RESP,
+	NAT_CON_TYPE_LOCAL_REJECT,
 	NAT_CON_TYPE_OTHER,
 };
 

openbsc/src/nat/bsc_nat.c

@@ -301,22 +301,66 @@ static void bsc_send_con_refuse(struct bsc_connection *bsc,
 	struct msgb *payload;
 	struct msgb *refuse;
 
-	if (con_type == NAT_CON_TYPE_LU) {
+	if (con_type == NAT_CON_TYPE_LU)
 		payload = gsm48_create_loc_upd_rej(GSM48_REJECT_PLMN_NOT_ALLOWED);
-		gsm0808_prepend_dtap_header(payload, 0);
-	} else if (con_type == NAT_CON_TYPE_CM_SERV_REQ) {
+	else if (con_type == NAT_CON_TYPE_CM_SERV_REQ)
 		payload = gsm48_create_mm_serv_rej(GSM48_REJECT_PLMN_NOT_ALLOWED);
+
+	/*
+	 * Some BSCs do not handle the payload inside a SCCP CREF msg
+	 * so we will need to:
+	 * 1.) Allocate a local connection and mark it as local..
+	 * 2.) queue data for downstream.. and the RLC should delete everything
+	 */
+	if (payload) {
+		struct msgb *cc, *udt, *rlsd;
+		struct sccp_connections *con;
+		con = create_sccp_src_ref(bsc, parsed);
+		if (!con)
+			goto send_refuse;
+
+		/* declare it local and assign a unique remote_ref */
+		con->con_type = NAT_CON_TYPE_LOCAL_REJECT;
+		con->con_local = 1;
+		con->has_remote_ref = 1;
+		con->remote_ref = con->patched_ref;
+
+		/* 1. create a confirmation */
+		cc = sccp_create_cc(&con->remote_ref, &con->real_ref);
+		if (!cc)
+			goto send_refuse;
+
+		/* 2. create the DT1 */
 		gsm0808_prepend_dtap_header(payload, 0);
+		udt = sccp_create_dt1(&con->real_ref, payload->data, payload->len);
+		if (!udt) {
+			msgb_free(cc);
+			goto send_refuse;
+		}
+
+		/* 3. send a RLSD */
+		rlsd = sccp_create_rlsd(&con->remote_ref, &con->real_ref,
+					SCCP_RELEASE_CAUSE_END_USER_ORIGINATED);
+		if (!rlsd) {
+			msgb_free(cc);
+			msgb_free(udt);
+			goto send_refuse;
+		}
+
+		bsc_write(bsc, cc, IPAC_PROTO_SCCP);
+		bsc_write(bsc, udt, IPAC_PROTO_SCCP);
+		bsc_write(bsc, rlsd, IPAC_PROTO_SCCP);
+		msgb_free(payload);
+		return;
 	}
 
-	refuse = sccp_create_refuse(parsed->src_local_ref,
-				    SCCP_REFUSAL_SCCP_FAILURE,
-				    payload ? payload->data : NULL,
-				    payload ? payload->len : 0);
 
+send_refuse:
 	if (payload)
 		msgb_free(payload);
 
+	refuse = sccp_create_refuse(parsed->src_local_ref,
+				    SCCP_REFUSAL_SCCP_FAILURE, NULL, 0);
 	if (!refuse) {
 		LOGP(DNAT, LOGL_ERROR,
 		     "Creating refuse msg failed for SCCP 0x%x on BSC Nr: %d.\n",

openbsc/src/nat/bsc_nat_utils.c

@@ -395,6 +395,7 @@ static const char *con_types [] = {
 	[NAT_CON_TYPE_LU] = "Location Update",
 	[NAT_CON_TYPE_CM_SERV_REQ] = "CM Serv Req",
 	[NAT_CON_TYPE_PAG_RESP] = "Paging Response",
+	[NAT_CON_TYPE_LOCAL_REJECT] = "Local Reject",
 	[NAT_CON_TYPE_OTHER] = "Other",
 };