filter: Separate SCCP/BSSAP extraction and gsm48 code
For the BSC we will have the gsm48_hdr and don't need to
find data within SCCP. For legacy reasons we need to
initialize con_type, imsi, reject causes early on and
need to do the same in the filter method.
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_filter.c b/openbsc/src/osmo-bsc_nat/bsc_nat_filter.c
new file mode 100644
index 0000000..11d370c
--- /dev/null
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_filter.c
@@ -0,0 +1,105 @@
+/*
+ * (C) 2010-2015 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010-2012 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/bsc_msg_filter.h>
+#include <openbsc/debug.h>
+
+#include <osmocom/gsm/gsm0808.h>
+
+#include <osmocom/gsm/protocol/gsm_08_08.h>
+#include <osmocom/gsm/protocol/gsm_04_11.h>
+
+#include <osmocom/sccp/sccp.h>
+
+/* Filter out CR data... */
+int bsc_nat_filter_sccp_cr(struct bsc_connection *bsc, struct msgb *msg,
+ struct bsc_nat_parsed *parsed, int *con_type,
+ char **imsi, struct bsc_filter_reject_cause *cause)
+{
+ struct tlv_parsed tp;
+ struct gsm48_hdr *hdr48;
+ int hdr48_len;
+ int len;
+
+ *con_type = NAT_CON_TYPE_NONE;
+ cause->cm_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
+ cause->lu_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
+ *imsi = NULL;
+
+ if (parsed->gsm_type != BSS_MAP_MSG_COMPLETE_LAYER_3) {
+ LOGP(DNAT, LOGL_ERROR,
+ "Rejecting CR message due wrong GSM Type %d\n", parsed->gsm_type);
+ return -1;
+ }
+
+ /* the parsed has had some basic l3 length check */
+ len = msg->l3h[1];
+ if (msgb_l3len(msg) - 3 < len) {
+ LOGP(DNAT, LOGL_ERROR,
+ "The CR Data has not enough space...\n");
+ return -1;
+ }
+
+ msg->l4h = &msg->l3h[3];
+ len -= 1;
+
+ tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h, len, 0, 0);
+
+ if (!TLVP_PRESENT(&tp, GSM0808_IE_LAYER_3_INFORMATION)) {
+ LOGP(DNAT, LOGL_ERROR, "CR Data does not contain layer3 information.\n");
+ return -1;
+ }
+
+ hdr48_len = TLVP_LEN(&tp, GSM0808_IE_LAYER_3_INFORMATION);
+
+ if (hdr48_len < sizeof(*hdr48)) {
+ LOGP(DNAT, LOGL_ERROR, "GSM48 header does not fit.\n");
+ return -1;
+ }
+
+ hdr48 = (struct gsm48_hdr *) TLVP_VAL(&tp, GSM0808_IE_LAYER_3_INFORMATION);
+ return bsc_msg_filter_initial(hdr48, hdr48_len, bsc, con_type, imsi, cause);
+}
+
+int bsc_nat_filter_dt(struct bsc_connection *bsc, struct msgb *msg,
+ struct nat_sccp_connection *con, struct bsc_nat_parsed *parsed,
+ struct bsc_filter_reject_cause *cause)
+{
+ uint32_t len;
+ struct gsm48_hdr *hdr48;
+
+ cause->cm_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
+ cause->lu_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
+
+ if (con->imsi_checked)
+ return 0;
+
+ /* only care about DTAP messages */
+ if (parsed->bssap != BSSAP_MSG_DTAP)
+ return 0;
+
+ hdr48 = bsc_unpack_dtap(parsed, msg, &len);
+ if (!hdr48)
+ return -1;
+
+ return bsc_msg_filter_data(hdr48, len, bsc, con, cause);
+}