1 files changed, 249 insertions, 0 deletions
diff --git a/src/osmo-bsc_nat/bsc_sccp.c b/src/osmo-bsc_nat/bsc_sccp.c
new file mode 100644
index 000000000..72de11201
--- /dev/null
+++ b/src/osmo-bsc_nat/bsc_sccp.c
@@ -0,0 +1,249 @@
+/* SCCP patching and handling routines */
+/*
+ * (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 Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <openbsc/debug.h>
+#include <openbsc/bsc_nat.h>
+#include <openbsc/bsc_nat_sccp.h>
+
+#include <osmocom/sccp/sccp.h>
+
+#include <osmocore/talloc.h>
+
+#include <string.h>
+#include <time.h>
+
+static int equal(struct sccp_source_reference *ref1, struct sccp_source_reference *ref2)
+{
+	return memcmp(ref1, ref2, sizeof(*ref1)) == 0;
+}
+
+/*
+ * SCCP patching below
+ */
+
+/* check if we are using this ref for patched already */
+static int sccp_ref_is_free(struct sccp_source_reference *ref, struct bsc_nat *nat)
+{
+	struct sccp_connections *conn;
+
+	llist_for_each_entry(conn, &nat->sccp_connections, list_entry) {
+		if (memcmp(ref, &conn->patched_ref, sizeof(*ref)) == 0)
+			return -1;
+	}
+
+	return 0;
+}
+
+/* copied from sccp.c */
+static int assign_src_local_reference(struct sccp_source_reference *ref, struct bsc_nat *nat)
+{
+	static uint32_t last_ref = 0x50000;
+	int wrapped = 0;
+
+	do {
+		struct sccp_source_reference reference;
+		reference.octet1 = (last_ref >>  0) & 0xff;
+		reference.octet2 = (last_ref >>  8) & 0xff;
+		reference.octet3 = (last_ref >> 16) & 0xff;
+
+		++last_ref;
+		/* do not use the reversed word and wrap around */
+		if ((last_ref & 0x00FFFFFF) == 0x00FFFFFF) {
+			LOGP(DNAT, LOGL_NOTICE, "Wrapped searching for a free code\n");
+			last_ref = 0;
+			++wrapped;
+		}
+
+		if (sccp_ref_is_free(&reference, nat) == 0) {
+			*ref = reference;
+			return 0;
+		}
+	} while (wrapped != 2);
+
+	LOGP(DNAT, LOGL_ERROR, "Finding a free reference failed\n");
+	return -1;
+}
+
+struct sccp_connections *create_sccp_src_ref(struct bsc_connection *bsc,
+					     struct bsc_nat_parsed *parsed)
+{
+	struct sccp_connections *conn;
+
+	/* Some commercial BSCs like to reassign there SRC ref */
+	llist_for_each_entry(conn, &bsc->nat->sccp_connections, list_entry) {
+		if (conn->bsc != bsc)
+			continue;
+		if (memcmp(&conn->real_ref, parsed->src_local_ref, sizeof(conn->real_ref)) != 0)
+			continue;
+
+		/* the BSC has reassigned the SRC ref and we failed to keep track */
+		memset(&conn->remote_ref, 0, sizeof(conn->remote_ref));
+		if (assign_src_local_reference(&conn->patched_ref, bsc->nat) != 0) {
+			LOGP(DNAT, LOGL_ERROR, "BSC %d reused src ref: %d and we failed to generate a new id.\n",
+			     bsc->cfg->nr, sccp_src_ref_to_int(parsed->src_local_ref));
+			bsc_mgcp_dlcx(conn);
+			llist_del(&conn->list_entry);
+			talloc_free(conn);
+			return NULL;
+		} else {
+			clock_gettime(CLOCK_MONOTONIC, &conn->creation_time);
+			bsc_mgcp_dlcx(conn);
+			return conn;
+		}
+	}
+
+
+	conn = talloc_zero(bsc->nat, struct sccp_connections);
+	if (!conn) {
+		LOGP(DNAT, LOGL_ERROR, "Memory allocation failure.\n");
+		return NULL;
+	}
+
+	conn->bsc = bsc;
+	clock_gettime(CLOCK_MONOTONIC, &conn->creation_time);
+	conn->real_ref = *parsed->src_local_ref;
+	if (assign_src_local_reference(&conn->patched_ref, bsc->nat) != 0) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to assign a ref.\n");
+		talloc_free(conn);
+		return NULL;
+	}
+
+	bsc_mgcp_init(conn);
+	llist_add_tail(&conn->list_entry, &bsc->nat->sccp_connections);
+	rate_ctr_inc(&bsc->cfg->stats.ctrg->ctr[BCFG_CTR_SCCP_CONN]);
+	counter_inc(bsc->cfg->nat->stats.sccp.conn);
+
+	LOGP(DNAT, LOGL_DEBUG, "Created 0x%x <-> 0x%x mapping for con %p\n",
+	     sccp_src_ref_to_int(&conn->real_ref),
+	     sccp_src_ref_to_int(&conn->patched_ref), bsc);
+
+	return conn;
+}
+
+int update_sccp_src_ref(struct sccp_connections *sccp, struct bsc_nat_parsed *parsed)
+{
+	if (!parsed->dest_local_ref || !parsed->src_local_ref) {
+		LOGP(DNAT, LOGL_ERROR, "CC MSG should contain both local and dest address.\n");
+		return -1;
+	}
+
+	sccp->remote_ref = *parsed->src_local_ref;
+	sccp->has_remote_ref = 1;
+	LOGP(DNAT, LOGL_DEBUG, "Updating 0x%x to remote 0x%x on %p\n",
+	     sccp_src_ref_to_int(&sccp->patched_ref),
+	     sccp_src_ref_to_int(&sccp->remote_ref), sccp->bsc);
+
+	return 0;
+}
+
+void remove_sccp_src_ref(struct bsc_connection *bsc, struct msgb *msg, struct bsc_nat_parsed *parsed)
+{
+	struct sccp_connections *conn;
+
+	llist_for_each_entry(conn, &bsc->nat->sccp_connections, list_entry) {
+		if (memcmp(parsed->src_local_ref,
+			   &conn->patched_ref, sizeof(conn->patched_ref)) == 0) {
+
+			sccp_connection_destroy(conn);
+			return;
+		}
+	}
+
+	LOGP(DNAT, LOGL_ERROR, "Can not remove connection: 0x%x\n",
+	     sccp_src_ref_to_int(parsed->src_local_ref));
+}
+
+/*
+ * We have a message from the MSC to the BSC. The MSC is using
+ * an address that was assigned by the MUX, we need to update the
+ * dest reference to the real network.
+ */
+struct sccp_connections *patch_sccp_src_ref_to_bsc(struct msgb *msg,
+						   struct bsc_nat_parsed *parsed,
+						   struct bsc_nat *nat)
+{
+	struct sccp_connections *conn;
+
+	if (!parsed->dest_local_ref) {
+		LOGP(DNAT, LOGL_ERROR, "MSG should contain dest_local_ref.\n");
+		return NULL;
+	}
+
+
+	llist_for_each_entry(conn, &nat->sccp_connections, list_entry) {
+		if (!equal(parsed->dest_local_ref, &conn->patched_ref))
+			continue;
+
+		/* Change the dest address to the real one */
+		*parsed->dest_local_ref = conn->real_ref;
+		return conn;
+	}
+
+	return NULL;
+}
+
+/*
+ * These are message to the MSC. We will need to find the BSC
+ * Connection by either the SRC or the DST local reference.
+ *
+ * In case of a CR we need to work by the SRC local reference
+ * in all other cases we need to work by the destination local
+ * reference..
+ */
+struct sccp_connections *patch_sccp_src_ref_to_msc(struct msgb *msg,
+						   struct bsc_nat_parsed *parsed,
+						   struct bsc_connection *bsc)
+{
+	struct sccp_connections *conn;
+
+	llist_for_each_entry(conn, &bsc->nat->sccp_connections, list_entry) {
+		if (conn->bsc != bsc)
+			continue;
+
+		if (parsed->src_local_ref) {
+			if (equal(parsed->src_local_ref, &conn->real_ref)) {
+				*parsed->src_local_ref = conn->patched_ref;
+				return conn;
+			}
+		} else if (parsed->dest_local_ref) {
+			if (equal(parsed->dest_local_ref, &conn->remote_ref))
+				return conn;
+		} else {
+			LOGP(DNAT, LOGL_ERROR, "Header has neither loc/dst ref.\n");
+			return NULL;
+		}
+	}
+
+	return NULL;
+}
+
+struct sccp_connections *bsc_nat_find_con_by_bsc(struct bsc_nat *nat,
+						 struct sccp_source_reference *ref)
+{
+	struct sccp_connections *conn;
+
+	llist_for_each_entry(conn, &nat->sccp_connections, list_entry) {
+		if (memcmp(ref, &conn->real_ref, sizeof(*ref)) == 0)
+			return conn;
+	}
+
+	return NULL;
+}