move openbsc/* to repos root

This is the first step in creating this repository from the legacy openbsc.git.

Like all other Osmocom repositories, keep the autoconf and automake files in
the repository root. openbsc.git has been the sole exception, which ends now.

Change-Id: I9c6f2a448d9cb1cc088cf1cf6918b69d7e69b4e7

1 files changed, 218 insertions, 0 deletions

diff --git a/src/osmo-bsc_nat/bsc_filter.c b/src/osmo-bsc_nat/bsc_filter.c
new file mode 100644
index 000000000..6a9e99fb8
--- /dev/null
+++ b/src/osmo-bsc_nat/bsc_filter.c
@@ -0,0 +1,218 @@
+/* BSC Multiplexer/NAT */
+
+/*
+ * (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/bsc_nat.h>
+#include <openbsc/bsc_nat_sccp.h>
+#include <openbsc/ipaccess.h>
+#include <openbsc/debug.h>
+
+#include <osmocom/core/talloc.h>
+#include <osmocom/gsm/protocol/gsm_08_08.h>
+
+#include <osmocom/sccp/sccp.h>
+
+/*
+ * The idea is to have a simple struct describing a IPA packet with
+ * SCCP SSN and the GSM 08.08 payload and decide. We will both have
+ * a white and a blacklist of packets we want to handle.
+ *
+ * TODO: Implement a "NOT" in the filter language.
+ */
+
+#define ALLOW_ANY -1
+
+#define FILTER_TO_BSC	1
+#define FILTER_TO_MSC	2
+#define FILTER_TO_BOTH	3
+
+
+struct bsc_pkt_filter {
+	int ipa_proto;
+	int dest_ssn;
+	int bssap;
+	int gsm;
+	int filter_dir;
+};
+
+static struct bsc_pkt_filter black_list[] = {
+	/* filter reset messages to the MSC */
+	{ IPAC_PROTO_SCCP, SCCP_SSN_BSSAP, 0, BSS_MAP_MSG_RESET, FILTER_TO_MSC },
+
+	/* filter reset ack messages to the BSC */
+	{ IPAC_PROTO_SCCP, SCCP_SSN_BSSAP, 0, BSS_MAP_MSG_RESET_ACKNOWLEDGE, FILTER_TO_BSC },
+
+	/* filter ip access */
+	{ IPAC_PROTO_IPACCESS, ALLOW_ANY, ALLOW_ANY, ALLOW_ANY, FILTER_TO_MSC },
+};
+
+static struct bsc_pkt_filter white_list[] = {
+	/* allow IPAC_PROTO_SCCP messages to both sides */
+	{ IPAC_PROTO_SCCP, ALLOW_ANY, ALLOW_ANY, ALLOW_ANY, FILTER_TO_BOTH },
+
+	/* allow MGCP messages to both sides */
+	{ IPAC_PROTO_MGCP_OLD, ALLOW_ANY, ALLOW_ANY, ALLOW_ANY, FILTER_TO_BOTH },
+};
+
+struct bsc_nat_parsed *bsc_nat_parse(struct msgb *msg)
+{
+	struct sccp_parse_result result;
+	struct bsc_nat_parsed *parsed;
+	struct ipaccess_head *hh;
+
+	/* quick fail */
+	if (msg->len < 4)
+		return NULL;
+
+	parsed = talloc_zero(msg, struct bsc_nat_parsed);
+	if (!parsed)
+		return NULL;
+
+	/* more init */
+	parsed->ipa_proto = parsed->called_ssn = parsed->calling_ssn = -1;
+	parsed->sccp_type = parsed->bssap = parsed->gsm_type = -1;
+
+	/* start parsing */
+	hh = (struct ipaccess_head *) msg->data;
+	parsed->ipa_proto = hh->proto;
+
+	msg->l2h = &hh->data[0];
+
+	/* do a size check on the input */
+	if (ntohs(hh->len) != msgb_l2len(msg)) {
+		LOGP(DLINP, LOGL_ERROR, "Wrong input length?\n");
+		talloc_free(parsed);
+		return NULL;
+	}
+
+	/* analyze sccp down here */
+	if (parsed->ipa_proto == IPAC_PROTO_SCCP) {
+		memset(&result, 0, sizeof(result));
+		if (sccp_parse_header(msg, &result) != 0) {
+			talloc_free(parsed);
+			return 0;
+		}
+
+		if (msg->l3h && msgb_l3len(msg) < 3) {
+			LOGP(DNAT, LOGL_ERROR, "Not enough space or GSM payload\n");
+			talloc_free(parsed);
+			return 0;
+		}
+
+		parsed->sccp_type = sccp_determine_msg_type(msg);
+		parsed->src_local_ref = result.source_local_reference;
+		parsed->dest_local_ref = result.destination_local_reference;
+		if (parsed->dest_local_ref)
+			parsed->original_dest_ref = *parsed->dest_local_ref;
+		parsed->called_ssn = result.called.ssn;
+		parsed->calling_ssn = result.calling.ssn;
+
+		/* in case of connection confirm we have no payload */
+		if (msg->l3h) {
+			parsed->bssap = msg->l3h[0];
+			parsed->gsm_type = msg->l3h[2];
+		}
+	}
+
+	return parsed;
+}
+
+int bsc_nat_filter_ipa(int dir, struct msgb *msg, struct bsc_nat_parsed *parsed)
+{
+	int i;
+
+	/* go through the blacklist now */
+	for (i = 0; i < ARRAY_SIZE(black_list); ++i) {
+		/* ignore the rule? */
+		if (black_list[i].filter_dir != FILTER_TO_BOTH
+		    && black_list[i].filter_dir != dir)
+			continue;
+
+		/* the proto is not blacklisted */
+		if (black_list[i].ipa_proto != ALLOW_ANY
+		    && black_list[i].ipa_proto != parsed->ipa_proto)
+			continue;
+
+		if (parsed->ipa_proto == IPAC_PROTO_SCCP) {
+			/* the SSN is not blacklisted */
+			if (black_list[i].dest_ssn != ALLOW_ANY
+			    && black_list[i].dest_ssn != parsed->called_ssn)
+				continue;
+
+			/* bssap */
+			if (black_list[i].bssap != ALLOW_ANY
+			    && black_list[i].bssap != parsed->bssap)
+				continue;
+
+			/* gsm */
+			if (black_list[i].gsm != ALLOW_ANY
+			    && black_list[i].gsm != parsed->gsm_type)
+				continue;
+
+			/* blacklisted */
+			LOGP(DNAT, LOGL_INFO, "Blacklisted with rule %d\n", i);
+			return 1;
+		} else {
+			/* blacklisted, we have no content sniffing yet */
+			LOGP(DNAT, LOGL_INFO, "Blacklisted with rule %d\n", i);
+			return 1;
+		}
+	}
+
+	/* go through the whitelust now */
+	for (i = 0; i < ARRAY_SIZE(white_list); ++i) {
+		/* ignore the rule? */
+		if (white_list[i].filter_dir != FILTER_TO_BOTH
+		    && white_list[i].filter_dir != dir)
+			continue;
+
+		/* the proto is not whitelisted */
+		if (white_list[i].ipa_proto != ALLOW_ANY
+		    && white_list[i].ipa_proto != parsed->ipa_proto)
+			continue;
+
+		if (parsed->ipa_proto == IPAC_PROTO_SCCP) {
+			/* the SSN is not whitelisted */
+			if (white_list[i].dest_ssn != ALLOW_ANY
+			    && white_list[i].dest_ssn != parsed->called_ssn)
+				continue;
+
+			/* bssap */
+			if (white_list[i].bssap != ALLOW_ANY
+			    && white_list[i].bssap != parsed->bssap)
+				continue;
+
+			/* gsm */
+			if (white_list[i].gsm != ALLOW_ANY
+			    && white_list[i].gsm != parsed->gsm_type)
+				continue;
+
+			/* whitelisted */
+			LOGP(DNAT, LOGL_INFO, "Whitelisted with rule %d\n", i);
+			return 0;
+		} else {
+			/* whitelisted */
+			return 0;
+		}
+	}
+
+	return 1;
+}