1 files changed, 453 insertions, 0 deletions

diff --git a/src/osmo-bsc_nat/bsc_ussd.c b/src/osmo-bsc_nat/bsc_ussd.c
new file mode 100644
index 000000000..0ba63270d
--- /dev/null
+++ b/src/osmo-bsc_nat/bsc_ussd.c
@@ -0,0 +1,453 @@
+/* USSD Filter Code */
+
+/*
+ * (C) 2010-2011 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010-2011 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/ipaccess.h>
+#include <openbsc/socket.h>
+
+#include <osmocom/gsm/protocol/gsm_08_08.h>
+#include <osmocom/gsm/gsm0480.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/gsm/tlv.h>
+#include <osmocom/gsm/ipa.h>
+
+#include <osmocom/sccp/sccp.h>
+
+#include <osmocom/abis/ipa.h>
+
+#include <sys/socket.h>
+#include <string.h>
+#include <unistd.h>
+
+#define USSD_LAC_IE	0
+#define USSD_CI_IE	1
+
+static void ussd_auth_con(struct tlv_parsed *, struct bsc_nat_ussd_con *);
+
+static struct bsc_nat_ussd_con *bsc_nat_ussd_alloc(struct bsc_nat *nat)
+{
+	struct bsc_nat_ussd_con *con;
+
+	con = talloc_zero(nat, struct bsc_nat_ussd_con);
+	if (!con)
+		return NULL;
+
+	con->nat = nat;
+	return con;
+}
+
+static void bsc_nat_ussd_destroy(struct bsc_nat_ussd_con *con)
+{
+	if (con->nat->ussd_con == con) {
+		bsc_ussd_close_connections(con->nat);
+		con->nat->ussd_con = NULL;
+	}
+
+	close(con->queue.bfd.fd);
+	osmo_fd_unregister(&con->queue.bfd);
+	osmo_timer_del(&con->auth_timeout);
+	osmo_wqueue_clear(&con->queue);
+
+	msgb_free(con->pending_msg);
+	talloc_free(con);
+}
+
+static void ussd_pong(struct bsc_nat_ussd_con *conn)
+{
+	struct msgb *msg;
+
+	msg = msgb_alloc_headroom(4096, 128, "pong message");
+	if (!msg) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate pong msg\n");
+		return;
+	}
+
+	msgb_v_put(msg, IPAC_MSGT_PONG);
+	bsc_do_write(&conn->queue, msg, IPAC_PROTO_IPACCESS);
+}
+
+static int forward_sccp(struct bsc_nat *nat, struct msgb *msg)
+{
+	struct nat_sccp_connection *con;
+	struct bsc_nat_parsed *parsed;
+
+
+	parsed = bsc_nat_parse(msg);
+	if (!parsed) {
+		LOGP(DNAT, LOGL_ERROR, "Can not parse msg from USSD.\n");
+		msgb_free(msg);
+		return -1;
+	}
+
+	if (!parsed->dest_local_ref) {
+		LOGP(DNAT, LOGL_ERROR, "No destination local reference.\n");
+		msgb_free(msg);
+		return -1;
+	}
+
+	con = bsc_nat_find_con_by_bsc(nat, parsed->dest_local_ref);
+	if (!con || !con->bsc) {
+		LOGP(DNAT, LOGL_ERROR, "No active connection found.\n");
+		msgb_free(msg);
+		return -1;
+	}
+
+	talloc_free(parsed);
+	bsc_write_msg(&con->bsc->write_queue, msg);
+	return 0;
+}
+
+static int ussd_read_cb(struct osmo_fd *bfd)
+{
+	struct bsc_nat_ussd_con *conn = bfd->data;
+	struct msgb *msg = NULL;
+	struct ipaccess_head *hh;
+	int ret;
+
+	ret = ipa_msg_recv_buffered(bfd->fd, &msg, &conn->pending_msg);
+	if (ret <= 0) {
+		if (ret == -EAGAIN)
+			return 0;
+		LOGP(DNAT, LOGL_ERROR, "USSD Connection was lost.\n");
+		bsc_nat_ussd_destroy(conn);
+		return -1;
+	}
+
+	LOGP(DNAT, LOGL_NOTICE, "MSG from USSD: %s proto: %d\n",
+		osmo_hexdump(msg->data, msg->len), msg->l2h[0]);
+	hh = (struct ipaccess_head *) msg->data;
+
+	if (hh->proto == IPAC_PROTO_IPACCESS) {
+		if (msg->l2h[0] == IPAC_MSGT_ID_RESP) {
+			struct tlv_parsed tvp;
+			int ret;
+			ret = ipa_ccm_idtag_parse(&tvp,
+					     (unsigned char *) msg->l2h + 2,
+					     msgb_l2len(msg) - 2);
+			if (ret < 0) {
+				LOGP(DNAT, LOGL_ERROR, "ignoring IPA response "
+					"message with malformed TLVs\n");
+				msgb_free(msg);
+				return ret;
+			}
+			if (TLVP_PRESENT(&tvp, IPAC_IDTAG_UNITNAME))
+				ussd_auth_con(&tvp, conn);
+		} else if (msg->l2h[0] == IPAC_MSGT_PING) {
+			LOGP(DNAT, LOGL_DEBUG, "Got USSD ping request.\n");
+			ussd_pong(conn);
+		} else {
+			LOGP(DNAT, LOGL_NOTICE, "Got unknown IPACCESS message 0x%02x.\n", msg->l2h[0]);
+		}
+
+		msgb_free(msg);
+	} else if (hh->proto == IPAC_PROTO_SCCP) {
+		forward_sccp(conn->nat, msg);
+	} else {
+		msgb_free(msg);
+	}
+
+	return 0;
+}
+
+static void ussd_auth_cb(void *_data)
+{
+	LOGP(DNAT, LOGL_ERROR, "USSD module didn't authenticate\n");
+	bsc_nat_ussd_destroy((struct bsc_nat_ussd_con *) _data);
+}
+
+static void ussd_auth_con(struct tlv_parsed *tvp, struct bsc_nat_ussd_con *conn)
+{
+	const char *token;
+	int len;
+	if (!conn->nat->ussd_token) {
+		LOGP(DNAT, LOGL_ERROR, "No USSD token set. Closing\n");
+		bsc_nat_ussd_destroy(conn);
+		return;
+	}
+
+	token = (const char *) TLVP_VAL(tvp, IPAC_IDTAG_UNITNAME);
+ 	len = TLVP_LEN(tvp, IPAC_IDTAG_UNITNAME);
+
+	/* last byte should be a NULL */
+	if (strlen(conn->nat->ussd_token) != len - 1)
+		goto disconnect;
+	/* compare everything including the null byte */
+	if (memcmp(conn->nat->ussd_token, token, len) != 0)
+		goto disconnect;
+
+	/* it is authenticated now */
+	if (conn->nat->ussd_con && conn->nat->ussd_con != conn)
+		bsc_nat_ussd_destroy(conn->nat->ussd_con);
+
+	LOGP(DNAT, LOGL_ERROR, "USSD token specified. USSD provider is connected.\n");
+	osmo_timer_del(&conn->auth_timeout);
+	conn->authorized = 1;
+	conn->nat->ussd_con = conn;
+	return;
+
+disconnect:
+	LOGP(DNAT, LOGL_ERROR, "Wrong USSD token by client: %d\n",
+		conn->queue.bfd.fd);
+	bsc_nat_ussd_destroy(conn);
+}
+
+static void ussd_start_auth(struct bsc_nat_ussd_con *conn)
+{
+	struct msgb *msg;
+
+	osmo_timer_setup(&conn->auth_timeout, ussd_auth_cb, conn);
+	osmo_timer_schedule(&conn->auth_timeout, conn->nat->auth_timeout, 0);
+
+	msg = msgb_alloc_headroom(4096, 128, "auth message");
+	if (!msg) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate auth msg\n");
+		return;
+	}
+
+	msgb_v_put(msg, IPAC_MSGT_ID_GET);
+	bsc_do_write(&conn->queue, msg, IPAC_PROTO_IPACCESS);
+}
+
+static int ussd_listen_cb(struct osmo_fd *bfd, unsigned int what)
+{
+	struct bsc_nat_ussd_con *conn;
+	struct bsc_nat *nat;
+	struct sockaddr_in sa;
+	socklen_t sa_len = sizeof(sa);
+	int fd;
+
+	if (!(what & BSC_FD_READ))
+		return 0;
+
+	fd = accept(bfd->fd, (struct sockaddr *) &sa, &sa_len);
+	if (fd < 0) {
+		perror("accept");
+		return fd;
+	}
+
+	nat = (struct bsc_nat *) bfd->data;
+	osmo_counter_inc(nat->stats.ussd.reconn);
+
+	conn = bsc_nat_ussd_alloc(nat);
+	if (!conn) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate USSD con struct.\n");
+		close(fd);
+		return -1;
+	}
+
+	osmo_wqueue_init(&conn->queue, 10);
+	conn->queue.bfd.data = conn;
+	conn->queue.bfd.fd = fd;
+	conn->queue.bfd.when = BSC_FD_READ;
+	conn->queue.read_cb = ussd_read_cb;
+	conn->queue.write_cb = bsc_write_cb;
+
+	if (osmo_fd_register(&conn->queue.bfd) < 0) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to register USSD fd.\n");
+		bsc_nat_ussd_destroy(conn);
+		return -1;
+	}
+
+	LOGP(DNAT, LOGL_NOTICE, "USSD Connection on %d with IP: %s\n",
+	     fd, inet_ntoa(sa.sin_addr));
+
+	/* do authentication */
+	ussd_start_auth(conn);
+	return 0;
+}
+
+int bsc_ussd_init(struct bsc_nat *nat)
+{
+	struct in_addr addr;
+
+	addr.s_addr = INADDR_ANY;
+	if (nat->ussd_local)
+		inet_aton(nat->ussd_local, &addr);
+
+	nat->ussd_listen.data = nat;
+	return make_sock(&nat->ussd_listen, IPPROTO_TCP,
+			 ntohl(addr.s_addr), 5001, 0, ussd_listen_cb, nat);
+}
+
+static int forward_ussd_simple(struct nat_sccp_connection *con, struct msgb *input)
+{
+	struct msgb *copy;
+	struct bsc_nat_ussd_con *ussd;
+
+	if (!con->bsc->nat->ussd_con)
+		return -1;
+
+	copy = msgb_alloc_headroom(4096, 128, "forward bts");
+	if (!copy) {
+		LOGP(DNAT, LOGL_ERROR, "Allocation failed, not forwarding.\n");
+		return -1;
+	}
+
+	/* copy the data into the copy */
+	copy->l2h = msgb_put(copy, msgb_l2len(input));
+	memcpy(copy->l2h, input->l2h, msgb_l2len(input));
+
+	/* send it out */
+	ussd = con->bsc->nat->ussd_con;
+	bsc_do_write(&ussd->queue, copy, IPAC_PROTO_SCCP);
+	return 0;
+}
+
+static int forward_ussd(struct nat_sccp_connection *con, const struct ussd_request *req,
+			struct msgb *input)
+{
+	struct msgb *msg, *copy;
+	struct ipac_msgt_sccp_state *state;
+	struct bsc_nat_ussd_con *ussd;
+	uint16_t lac, ci;
+
+	if (!con->bsc->nat->ussd_con)
+		return -1;
+
+	msg = msgb_alloc_headroom(4096, 128, "forward ussd");
+	if (!msg) {
+		LOGP(DNAT, LOGL_ERROR, "Allocation failed, not forwarding.\n");
+		return -1;
+	}
+
+	copy = msgb_alloc_headroom(4096, 128, "forward bts");
+	if (!copy) {
+		LOGP(DNAT, LOGL_ERROR, "Allocation failed, not forwarding.\n");
+		msgb_free(msg);
+		return -1;
+	}
+
+	copy->l2h = msgb_put(copy, msgb_l2len(input));
+	memcpy(copy->l2h, input->l2h, msgb_l2len(input));
+
+	msg->l2h = msgb_put(msg, 1);
+	msg->l2h[0] = IPAC_MSGT_SCCP_OLD;
+
+	/* fill out the data */
+	state = (struct ipac_msgt_sccp_state *) msgb_put(msg, sizeof(*state));
+	state->trans_id = req->transaction_id;
+	state->invoke_id = req->invoke_id;
+	memcpy(&state->src_ref, &con->remote_ref, sizeof(con->remote_ref));
+	memcpy(&state->dst_ref, &con->real_ref, sizeof(con->real_ref));
+	memcpy(state->imsi, con->filter_state.imsi, strlen(con->filter_state.imsi));
+
+	/* add additional tag/values */
+	lac = htons(con->lac);
+	ci = htons(con->ci);
+	msgb_tv_fixed_put(msg, USSD_LAC_IE, sizeof(lac), (const uint8_t *) &lac);
+	msgb_tv_fixed_put(msg, USSD_CI_IE, sizeof(ci), (const uint8_t *) &ci);
+
+	ussd = con->bsc->nat->ussd_con;
+	bsc_do_write(&ussd->queue, msg, IPAC_PROTO_IPACCESS);
+	bsc_do_write(&ussd->queue, copy, IPAC_PROTO_SCCP);
+
+	return 0;
+}
+
+int bsc_ussd_check(struct nat_sccp_connection *con, struct bsc_nat_parsed *parsed,
+		   struct msgb *msg)
+{
+	uint32_t len;
+	uint8_t msg_type;
+	uint8_t proto;
+	uint8_t ti;
+	struct gsm48_hdr *hdr48;
+	struct bsc_msg_acc_lst *lst;
+	struct ussd_request req;
+
+	/*
+	 * various checks to avoid the decoding work. Right now we only want to
+	 * decode if the connection was created for USSD, we do have a USSD access
+	 * list, a query, a IMSI and such...
+	 */
+	if (con->filter_state.con_type != FLT_CON_TYPE_SSA)
+		return 0;
+
+	if (!con->filter_state.imsi)
+		return 0;
+
+	/* We have not verified the IMSI yet */
+	if (!con->authorized)
+		return 0;
+
+	if (!con->bsc->nat->ussd_lst_name)
+		return 0;
+	if (!con->bsc->nat->ussd_query)
+		return 0;
+
+	if (parsed->bssap != BSSAP_MSG_DTAP)
+		return 0;
+
+	if (strlen(con->filter_state.imsi) > GSM23003_IMSI_MAX_DIGITS)
+		return 0;
+
+	hdr48 = bsc_unpack_dtap(parsed, msg, &len);
+	if (!hdr48)
+		return 0;
+
+	proto = gsm48_hdr_pdisc(hdr48);
+	msg_type = gsm48_hdr_msg_type(hdr48);
+	ti = gsm48_hdr_trans_id_no_ti(hdr48);
+	if (proto != GSM48_PDISC_NC_SS)
+		return 0;
+
+	if (msg_type == GSM0480_MTYPE_REGISTER) {
+
+		/* now check if it is a IMSI we care about */
+		lst = bsc_msg_acc_lst_find(&con->bsc->nat->access_lists,
+					   con->bsc->nat->ussd_lst_name);
+		if (!lst)
+			return 0;
+
+		if (bsc_msg_acc_lst_check_allow(lst, con->filter_state.imsi) != 0)
+			return 0;
+
+		/* now decode the message and see if we really want to handle it */
+		memset(&req, 0, sizeof(req));
+		if (gsm0480_decode_ussd_request(hdr48, len, &req) != 1)
+			return 0;
+		if (req.text[0] == 0xff)
+			return 0;
+
+		if (regexec(&con->bsc->nat->ussd_query_re,
+			    req.text, 0, NULL, 0) == REG_NOMATCH)
+			return 0;
+
+		/* found a USSD query for our subscriber */
+		LOGP(DNAT, LOGL_NOTICE, "Found USSD query for %s\n",
+			con->filter_state.imsi);
+		con->ussd_ti[ti] = 1;
+		if (forward_ussd(con, &req, msg) != 0)
+			return 0;
+		return 1;
+	} else if (msg_type == GSM0480_MTYPE_FACILITY && con->ussd_ti[ti]) {
+		LOGP(DNAT, LOGL_NOTICE, "Forwarding message part of TI: %d %s\n",
+		     ti, con->filter_state.imsi);
+		if (forward_ussd_simple(con, msg) != 0)
+			return 0;
+		return 1;
+	}
+
+	return 0;
+}