333 lines
8.4 KiB
C
333 lines
8.4 KiB
C
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/* BSC Multiplexer/NAT Utilities */
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/*
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* (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
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* (C) 2010 by On-Waves
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include <openbsc/bsc_nat.h>
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#include <openbsc/gsm_data.h>
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#include <openbsc/bssap.h>
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#include <openbsc/debug.h>
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#include <openbsc/ipaccess.h>
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#include <osmocore/linuxlist.h>
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#include <osmocore/talloc.h>
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#include <osmocore/gsm0808.h>
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#include <sccp/sccp.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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struct bsc_nat *bsc_nat_alloc(void)
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{
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struct bsc_nat *nat = talloc_zero(tall_bsc_ctx, struct bsc_nat);
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if (!nat)
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return NULL;
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INIT_LLIST_HEAD(&nat->sccp_connections);
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INIT_LLIST_HEAD(&nat->bsc_connections);
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INIT_LLIST_HEAD(&nat->bsc_configs);
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nat->stats.sccp.conn = counter_alloc("nat.sccp.conn");
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nat->stats.sccp.calls = counter_alloc("nat.sccp.calls");
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nat->stats.bsc.reconn = counter_alloc("nat.bsc.conn");
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nat->stats.bsc.auth_fail = counter_alloc("nat.bsc.auth_fail");
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nat->stats.msc.reconn = counter_alloc("nat.msc.conn");
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nat->msc_ip = talloc_strdup(nat, "127.0.0.1");
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nat->msc_port = 5000;
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nat->auth_timeout = 2;
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nat->ping_timeout = 20;
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nat->pong_timeout = 5;
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return nat;
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}
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void bsc_nat_set_msc_ip(struct bsc_nat *nat, const char *ip)
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{
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if (nat->msc_ip)
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talloc_free(nat->msc_ip);
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nat->msc_ip = talloc_strdup(nat, ip);
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}
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struct bsc_connection *bsc_connection_alloc(struct bsc_nat *nat)
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{
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struct bsc_connection *con = talloc_zero(nat, struct bsc_connection);
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if (!con)
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return NULL;
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con->nat = nat;
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write_queue_init(&con->write_queue, 100);
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return con;
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}
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struct bsc_config *bsc_config_alloc(struct bsc_nat *nat, const char *token, unsigned int lac)
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{
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struct bsc_config *conf = talloc_zero(nat, struct bsc_config);
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if (!conf)
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return NULL;
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conf->token = talloc_strdup(conf, token);
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conf->lac = lac;
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conf->nr = nat->num_bsc;
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conf->nat = nat;
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llist_add_tail(&conf->entry, &nat->bsc_configs);
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++nat->num_bsc;
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conf->stats.sccp.conn = counter_alloc("nat.bsc.sccp.conn");
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conf->stats.sccp.calls = counter_alloc("nat.bsc.sccp.calls");
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conf->stats.net.reconn = counter_alloc("nat.bsc.net.reconnects");
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return conf;
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}
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void sccp_connection_destroy(struct sccp_connections *conn)
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{
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LOGP(DNAT, LOGL_DEBUG, "Destroy 0x%x <-> 0x%x mapping for con %p\n",
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sccp_src_ref_to_int(&conn->real_ref),
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sccp_src_ref_to_int(&conn->patched_ref), conn->bsc);
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bsc_mgcp_dlcx(conn);
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llist_del(&conn->list_entry);
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talloc_free(conn);
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}
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struct bsc_connection *bsc_nat_find_bsc(struct bsc_nat *nat, struct msgb *msg, int *lac_out)
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{
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struct bsc_connection *bsc;
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int data_length;
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const u_int8_t *data;
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struct tlv_parsed tp;
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int i = 0;
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*lac_out = -1;
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if (!msg->l3h || msgb_l3len(msg) < 3) {
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LOGP(DNAT, LOGL_ERROR, "Paging message is too short.\n");
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return NULL;
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}
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tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 3, msgb_l3len(msg) - 3, 0, 0);
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if (!TLVP_PRESENT(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST)) {
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LOGP(DNAT, LOGL_ERROR, "No CellIdentifier List inside paging msg.\n");
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return NULL;
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}
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data_length = TLVP_LEN(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST);
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data = TLVP_VAL(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST);
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/* No need to try a different BSS */
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if (data[0] == CELL_IDENT_BSS) {
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return NULL;
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} else if (data[0] != CELL_IDENT_LAC) {
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LOGP(DNAT, LOGL_ERROR, "Unhandled cell ident discrminator: %d\n", data[0]);
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return NULL;
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}
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/* Currently we only handle one BSC */
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for (i = 1; i < data_length - 1; i += 2) {
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unsigned int _lac = ntohs(*(unsigned int *) &data[i]);
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*lac_out = _lac;
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llist_for_each_entry(bsc, &nat->bsc_connections, list_entry) {
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if (!bsc->cfg)
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continue;
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if (!bsc->authenticated || _lac != bsc->cfg->lac)
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continue;
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return bsc;
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}
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}
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return NULL;
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}
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int bsc_write_mgcp(struct bsc_connection *bsc, const u_int8_t *data, unsigned int length)
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{
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struct msgb *msg;
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if (length > 4096 - 128) {
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LOGP(DINP, LOGL_ERROR, "Can not send message of that size.\n");
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return -1;
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}
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msg = msgb_alloc_headroom(4096, 128, "to-bsc");
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if (!msg) {
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LOGP(DINP, LOGL_ERROR, "Failed to allocate memory for BSC msg.\n");
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return -1;
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}
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/* copy the data */
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msg->l3h = msgb_put(msg, length);
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memcpy(msg->l3h, data, length);
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return bsc_write(bsc, msg, NAT_IPAC_PROTO_MGCP);
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}
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int bsc_write(struct bsc_connection *bsc, struct msgb *msg, int proto)
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{
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/* prepend the header */
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ipaccess_prepend_header(msg, proto);
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if (write_queue_enqueue(&bsc->write_queue, msg) != 0) {
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LOGP(DINP, LOGL_ERROR, "Failed to enqueue the write.\n");
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msgb_free(msg);
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return -1;
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}
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return 0;
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}
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/* apply white/black list */
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static int auth_imsi(struct bsc_connection *bsc, const char *mi_string)
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{
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regmatch_t match[1];
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/*
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* Now apply blacklist/whitelist of the BSC and the NAT.
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* 1.) Reject if the IMSI is not allowed at the BSC
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* 2.) Allow directly if the IMSI is allowed at the BSC
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* 3.) Reject if the IMSI not allowed at the global level.
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* 4.) Allow directly if the IMSI is allowed at the global level
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*/
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/* 1. BSC deny */
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if (bsc->cfg->imsi_deny) {
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if (regexec(&bsc->cfg->imsi_deny_re, mi_string, 1, match, 0) == 0) {
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LOGP(DNAT, LOGL_ERROR,
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"Filtering %s by imsi_deny.\n", mi_string);
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return -2;
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}
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}
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/* 2. BSC allow */
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if (bsc->cfg->imsi_allow) {
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if (regexec(&bsc->cfg->imsi_allow_re, mi_string, 1, match, 0) == 0)
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return 0;
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}
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/* 3. NAT deny */
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if (bsc->nat->imsi_deny) {
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if (regexec(&bsc->nat->imsi_deny_re, mi_string, 1, match, 0) == 0) {
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LOGP(DNAT, LOGL_ERROR,
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"Filtering %s by nat imsi_deny.\n", mi_string);
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return -3;
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}
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}
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/* 4. NAT allow */
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if (bsc->nat->imsi_allow) {
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if (regexec(&bsc->nat->imsi_allow_re, mi_string, 0, NULL, 0) == 0)
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return 0;
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} else {
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return 0;
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}
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/* unmatched */
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return -3;
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}
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static int _cr_check_loc_upd(struct bsc_connection *bsc, uint8_t *data, unsigned int length)
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{
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u_int8_t mi_type;
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struct gsm48_loc_upd_req *lu;
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char mi_string[GSM48_MI_SIZE];
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if (length < sizeof(*lu)) {
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LOGP(DNAT, LOGL_ERROR,
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"LU does not fit. Length is %d \n", length);
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return -1;
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}
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lu = (struct gsm48_loc_upd_req *) data;
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mi_type = lu->mi[0] & GSM_MI_TYPE_MASK;
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/*
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* We can only deal with the IMSI. This will fail for a phone that
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* will send the TMSI of a previous network to us.
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*/
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if (mi_type != GSM_MI_TYPE_IMSI)
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return 0;
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gsm48_mi_to_string(mi_string, sizeof(mi_string), lu->mi, lu->mi_len);
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return auth_imsi(bsc, mi_string);
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}
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/* Filter out CR data... */
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int bsc_nat_filter_sccp_cr(struct bsc_connection *bsc, struct msgb *msg, struct bsc_nat_parsed *parsed)
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{
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struct tlv_parsed tp;
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struct gsm48_hdr *hdr48;
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int hdr48_len;
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int len;
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if (parsed->gsm_type != BSS_MAP_MSG_COMPLETE_LAYER_3) {
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LOGP(DNAT, LOGL_ERROR,
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"Rejecting CR message due wrong GSM Type %d\n", parsed->gsm_type);
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return -1;
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}
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/* the parsed has had some basic l3 length check */
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len = msg->l3h[1];
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if (msgb_l3len(msg) - 3 < len) {
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LOGP(DNAT, LOGL_ERROR,
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"The CR Data has not enough space...\n");
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return -1;
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}
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msg->l4h = &msg->l3h[3];
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len -= 1;
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tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h, len, 0, 0);
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if (!TLVP_PRESENT(&tp, GSM0808_IE_LAYER_3_INFORMATION)) {
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LOGP(DNAT, LOGL_ERROR, "CR Data does not contain layer3 information.\n");
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return -1;
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}
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hdr48_len = TLVP_LEN(&tp, GSM0808_IE_LAYER_3_INFORMATION);
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if (hdr48_len < sizeof(*hdr48)) {
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LOGP(DNAT, LOGL_ERROR, "GSM48 header does not fit.\n");
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return -1;
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}
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hdr48 = (struct gsm48_hdr *) TLVP_VAL(&tp, GSM0808_IE_LAYER_3_INFORMATION);
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if (hdr48->msg_type == GSM48_MT_MM_LOC_UPD_REQUEST) {
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return _cr_check_loc_upd(bsc, &hdr48->data[0], hdr48_len - sizeof(*hdr48));
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} else {
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return 0;
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}
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}
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void bsc_parse_reg(void *ctx, regex_t *reg, char **imsi, int argc, const char **argv)
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{
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if (*imsi) {
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talloc_free(*imsi);
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*imsi = NULL;
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}
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regfree(reg);
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if (argc > 0) {
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*imsi = talloc_strdup(ctx, argv[0]);
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regcomp(reg, argv[0], 0);
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}
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}
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