nat: Look at the assignment command and remember on which timeslot the data is

This information will be needed when we are trying to forward
MGCP connections to and from the BSC through the IPA protocol.

1 files changed, 66 insertions, 0 deletions

diff --git a/openbsc/src/nat/bsc_mgcp_utils.c b/openbsc/src/nat/bsc_mgcp_utils.c
new file mode 100644
index 000000000..55dad380a
--- /dev/null
+++ b/openbsc/src/nat/bsc_mgcp_utils.c
@@ -0,0 +1,66 @@
+/*
+ * (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010 by On-Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <openbsc/bsc_nat.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/bssap.h>
+#include <openbsc/debug.h>
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+int bsc_mgcp_assign(struct sccp_connections *con, struct msgb *msg)
+{
+	struct tlv_parsed tp;
+	u_int16_t cic;
+	u_int8_t timeslot;
+	u_int8_t multiplex;
+
+	if (!msg->l3h) {
+		LOGP(DNAT, LOGL_ERROR, "Assignment message should have l3h pointer.\n");
+		return -1;
+	}
+
+	if (msgb_l3len(msg) < 3) {
+		LOGP(DNAT, LOGL_ERROR, "Assignment message has not enough space for GSM0808.\n");
+		return -1;
+	}
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 3, msgb_l3len(msg) - 3, 0, 0);
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE)) {
+		LOGP(DNAT, LOGL_ERROR, "Circuit identity code not found in assignment message.\n");
+		return -1;
+	}
+
+	cic = ntohs(*(u_int16_t *)TLVP_VAL(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE));
+	timeslot = cic & 0x1f;
+	multiplex = (cic & ~0x1f) >> 5;
+
+	con->msc_timeslot = (32 * multiplex) + timeslot;
+	con->bsc_timeslot = con->msc_timeslot;
+	return 0;
+}
+
+void bsc_mgcp_clear(struct sccp_connections *con)
+{
+	con->msc_timeslot = -1;
+	con->bsc_timeslot = -1;
+}