diff options
Diffstat (limited to 'src/osmo-bsc_nat/bsc_ussd.c')
-rw-r--r-- | src/osmo-bsc_nat/bsc_ussd.c | 453 |
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; +} |