nat: Handle CRCX/MDCX/DLCX at the nat

* Forward a rewritten msg to the BSS. We change the IP and port
  to point to the NAT instead of the core network. We also keep
  track of the BSC and the transacition id.
* Handle the case where we have not found a SCCP connection and
  need to send a response ourselves.

1 files changed, 38 insertions, 0 deletions

diff --git a/openbsc/src/nat/bsc_nat_utils.c b/openbsc/src/nat/bsc_nat_utils.c
index dc6cfec5c..1c68e10fe 100644
--- a/openbsc/src/nat/bsc_nat_utils.c
+++ b/openbsc/src/nat/bsc_nat_utils.c
@@ -26,6 +26,7 @@
 #include <openbsc/gsm_data.h>
 #include <openbsc/bssap.h>
 #include <openbsc/debug.h>
+#include <openbsc/ipaccess.h>
 
 #include <osmocore/linuxlist.h>
 #include <osmocore/talloc.h>
@@ -123,3 +124,40 @@ struct bsc_connection *bsc_nat_find_bsc(struct bsc_nat *nat, struct msgb *msg)
 
 	return NULL;
 }
+
+int bsc_write_mgcp(struct bsc_connection *bsc, const u_int8_t *data, unsigned int length)
+{
+	struct msgb *msg;
+
+	if (length > 4096 - 128) {
+		LOGP(DINP, LOGL_ERROR, "Can not send message of that size.\n");
+		return -1;
+	}
+
+	msg = msgb_alloc_headroom(4096, 128, "to-bsc");
+	if (!msg) {
+		LOGP(DINP, LOGL_ERROR, "Failed to allocate memory for BSC msg.\n");
+		return -1;
+	}
+
+	/* copy the data */
+	msg->l3h = msgb_put(msg, length);
+	memcpy(msg->l3h, data, length);
+
+        return bsc_write_mgcp_msg(bsc, msg);
+}
+
+int bsc_write_mgcp_msg(struct bsc_connection *bsc, struct msgb *msg)
+{
+	/* prepend the header */
+	ipaccess_prepend_header(msg, NAT_IPAC_PROTO_MGCP);
+
+	if (write_queue_enqueue(&bsc->write_queue, msg) != 0) {
+		LOGP(DINP, LOGL_ERROR, "Failed to enqueue the write.\n");
+		msgb_free(msg);
+		return -1;
+	}
+
+	return 0;
+}
+