[nat] Prepare more sophisicated filtering and patching

Introduce a bsc_nat_parse method to parse a IP Access method
into various parts. Write out the IPA Proto, in case SCCP is used,
store the msg type, pointers to the source/dest local reference and
other information.

Use the result of bsc_nat_parse inside the bsc_nat_filter method
to decide if the message should be dropped or not.

In the future the bsc_nat_parse result will be used for patching
SCCP references and other parts of the message.

The filter language should be able to filter the msg type of SCCP
messages and gain the "NOT" word in the filter language.

2 files changed, 171 insertions, 1 deletions

diff --git a/openbsc/tests/Makefile.am b/openbsc/tests/Makefile.am
index f40105fbf..d867ec6bb 100644
--- a/openbsc/tests/Makefile.am
+++ b/openbsc/tests/Makefile.am
@@ -1 +1 @@
-SUBDIRS = debug timer sms gsm0408 db channel sccp
+SUBDIRS = debug timer sms gsm0408 db channel sccp bsc-nat
diff --git a/openbsc/tests/bsc-nat/bsc_nat_test.c b/openbsc/tests/bsc-nat/bsc_nat_test.c
new file mode 100644
index 000000000..282f2515b
--- /dev/null
+++ b/openbsc/tests/bsc-nat/bsc_nat_test.c
@@ -0,0 +1,170 @@
+/*
+ * BSC NAT Message filtering
+ *
+ * (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010 by on-waves.com
+ *
+ * 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/debug.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/bsc_nat.h>
+
+#include <stdio.h>
+
+/* test messages for ipa */
+static u_int8_t ipa_id[] = {
+	0x00, 0x01, 0xfe, 0x06,
+};
+
+/* SCCP messages are below */
+static u_int8_t gsm_reset[] = {
+	0x00, 0x12, 0xfd,
+	0x09, 0x00, 0x03, 0x05, 0x07, 0x02, 0x42, 0xfe,
+	0x02, 0x42, 0xfe, 0x06, 0x00, 0x04, 0x30, 0x04,
+	0x01, 0x20,
+};
+
+static const u_int8_t gsm_reset_ack[] = {
+	0x00, 0x13, 0xfd,
+	0x09, 0x00, 0x03, 0x07, 0x0b, 0x04, 0x43, 0x01,
+	0x00, 0xfe, 0x04, 0x43, 0x5c, 0x00, 0xfe, 0x03,
+	0x00, 0x01, 0x31,
+};
+
+static const u_int8_t gsm_paging[] = {
+	0x00, 0x20, 0xfd,
+	0x09, 0x00, 0x03, 0x07, 0x0b, 0x04, 0x43, 0x01,
+	0x00, 0xfe, 0x04, 0x43, 0x5c, 0x00, 0xfe, 0x10,
+	0x00, 0x0e, 0x52, 0x08, 0x08, 0x29, 0x47, 0x10,
+	0x02, 0x01, 0x31, 0x97, 0x61, 0x1a, 0x01, 0x06,
+};
+
+/* BSC -> MSC connection open */
+static const u_int8_t bssmap_cr[] = {
+	0x00, 0x2c, 0xfd,
+	0x01, 0x01, 0x02, 0x03, 0x02, 0x02, 0x04, 0x02,
+	0x42, 0xfe, 0x0f, 0x1f, 0x00, 0x1d, 0x57, 0x05,
+	0x08, 0x00, 0x72, 0xf4, 0x80, 0x20, 0x12, 0xc3,
+	0x50, 0x17, 0x10, 0x05, 0x24, 0x11, 0x03, 0x33,
+	0x19, 0xa2, 0x08, 0x29, 0x47, 0x10, 0x02, 0x01,
+	0x31, 0x97, 0x61, 0x00
+};
+
+/* MSC -> BSC connection confirm */
+static const u_int8_t bssmap_cc[] = {
+	0x00, 0x0a, 0xfd,
+	0x02, 0x01, 0x02, 0x03, 0x00, 0x00, 0x03, 0x02, 0x01, 0x00,
+};
+
+/* MSC -> BSC released */
+static const u_int8_t bssmap_released[] = {
+	0x00, 0x0e, 0xfd,
+	0x04, 0x00, 0x00, 0x03, 0x01, 0x02, 0x03, 0x00, 0x01, 0x0f,
+	0x02, 0x23, 0x42, 0x00,
+};
+
+/* BSC -> MSC released */
+static const u_int8_t bssmap_release_complete[] = {
+	0x00, 0x07, 0xfd,
+	0x05, 0x01, 0x02, 0x03, 0x00, 0x00, 0x03
+};
+
+struct filter_result {
+	const u_int8_t *data;
+	const u_int16_t length;
+	const int result;
+};
+
+static const struct filter_result results[] = {
+	{
+		.data = ipa_id,
+		.length = ARRAY_SIZE(ipa_id),
+		.result = FILTER_TO_MSC,
+	},
+	{
+		.data = gsm_reset,
+		.length = ARRAY_SIZE(gsm_reset),
+		.result = FILTER_TO_MSC,
+	},
+	{
+		.data = gsm_reset_ack,
+		.length = ARRAY_SIZE(gsm_reset_ack),
+		.result = FILTER_TO_BSC,
+	},
+	{
+		.data = gsm_paging,
+		.length = ARRAY_SIZE(gsm_paging),
+		.result = FILTER_NONE,
+	},
+	{
+		.data = bssmap_cr,
+		.length = ARRAY_SIZE(bssmap_cr),
+		.result = FILTER_NONE,
+	},
+	{
+		.data = bssmap_cc,
+		.length = ARRAY_SIZE(bssmap_cc),
+		.result = FILTER_NONE,
+	},
+	{
+		.data = bssmap_released,
+		.length = ARRAY_SIZE(bssmap_released),
+		.result = FILTER_NONE,
+	},
+	{
+		.data = bssmap_release_complete,
+		.length = ARRAY_SIZE(bssmap_release_complete),
+		.result = FILTER_NONE,
+	},
+};
+
+int main(int argc, char **argv)
+{
+	int i;
+
+
+	/* start testinh with proper messages */
+	for (i = 0; i < ARRAY_SIZE(results); ++i) {
+		int result;
+		struct bsc_nat_parsed *parsed;
+		struct msgb *msg = msgb_alloc(4096, "test-message");
+
+		fprintf(stderr, "Going to test item: %d\n", i);
+		memcpy(msg->data, results[i].data, results[i].length);
+		msg->l2h = msgb_put(msg, results[i].length);
+
+		parsed = bsc_nat_parse(msg);
+		if (!parsed) {
+			fprintf(stderr, "FAIL: Failed to parse the message\n");
+			continue;
+		}
+
+		result = bsc_nat_filter_ipa(msg, parsed);
+		if (result != results[i].result) {
+			fprintf(stderr, "FAIL: Not the expected result got: %d wanted: %d\n",
+				result, results[i].result);
+		}
+
+		msgb_free(msg);
+	}
+
+	return 0;
+}