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osmo-msc/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c

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/* BSC Multiplexer/NAT Utilities */
/*
* (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
* (C) 2010 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_msc.h>
#include <openbsc/gsm_data.h>
#include <openbsc/debug.h>
#include <openbsc/ipaccess.h>
#include <openbsc/vty.h>
#include <osmocore/linuxlist.h>
#include <osmocore/talloc.h>
#include <osmocore/gsm0808.h>
#include <osmocore/protocol/gsm_08_08.h>
#include <osmocom/sccp/sccp.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
static const struct rate_ctr_desc bsc_cfg_ctr_description[] = {
[BCFG_CTR_SCCP_CONN] = { "sccp.conn", "SCCP Connections "},
[BCFG_CTR_SCCP_CALLS] = { "sccp.calls", "SCCP Assignment Commands "},
[BCFG_CTR_NET_RECONN] = { "net.reconnects", "Network reconnects "},
[BCFG_CTR_DROPPED_SCCP] = { "dropped.sccp", "Dropped SCCP connections."},
[BCFG_CTR_DROPPED_CALLS] = { "dropped.calls", "Dropped active calls. "},
[BCFG_CTR_REJECTED_CR] = { "rejected.cr", "Rejected CR due filter "},
[BCFG_CTR_REJECTED_MSG] = { "rejected.msg", "Rejected MSG due filter "},
[BCFG_CTR_ILL_PACKET] = { "rejected.ill", "Rejected due parse error "},
[BCFG_CTR_CON_TYPE_LU] = { "conn.lu", "Conn Location Update "},
[BCFG_CTR_CON_CMSERV_RQ] = { "conn.rq", "Conn CM Service Req "},
[BCFG_CTR_CON_PAG_RESP] = { "conn.pag", "Conn Paging Response "},
[BCFG_CTR_CON_SSA] = { "conn.ssa", "Conn USSD "},
[BCFG_CTR_CON_OTHER] = { "conn.other", "Conn Other "},
};
static const struct rate_ctr_group_desc bsc_cfg_ctrg_desc = {
.group_name_prefix = "nat.bsc",
.group_description = "NAT BSC Statistics",
.num_ctr = ARRAY_SIZE(bsc_cfg_ctr_description),
.ctr_desc = bsc_cfg_ctr_description,
};
static const struct rate_ctr_desc acc_list_ctr_description[] = {
[ACC_LIST_BSC_FILTER] = { "access-list.bsc-filter", "Rejected by rule for BSC"},
[ACC_LIST_NAT_FILTER] = { "access-list.nat-filter", "Rejected by rule for NAT"},
};
static const struct rate_ctr_group_desc bsc_cfg_acc_list_desc = {
.group_name_prefix = "nat.filter",
.group_description = "NAT Access-List Statistics",
.num_ctr = ARRAY_SIZE(acc_list_ctr_description),
.ctr_desc = acc_list_ctr_description,
};
struct bsc_nat *bsc_nat_alloc(void)
{
struct bsc_nat *nat = talloc_zero(tall_bsc_ctx, struct bsc_nat);
if (!nat)
return NULL;
INIT_LLIST_HEAD(&nat->sccp_connections);
INIT_LLIST_HEAD(&nat->bsc_connections);
INIT_LLIST_HEAD(&nat->bsc_configs);
INIT_LLIST_HEAD(&nat->access_lists);
nat->stats.sccp.conn = counter_alloc("nat.sccp.conn");
nat->stats.sccp.calls = counter_alloc("nat.sccp.calls");
nat->stats.bsc.reconn = counter_alloc("nat.bsc.conn");
nat->stats.bsc.auth_fail = counter_alloc("nat.bsc.auth_fail");
nat->stats.msc.reconn = counter_alloc("nat.msc.conn");
nat->stats.ussd.reconn = counter_alloc("nat.ussd.conn");
nat->msc_ip = talloc_strdup(nat, "127.0.0.1");
nat->msc_port = 5000;
nat->auth_timeout = 2;
nat->ping_timeout = 20;
nat->pong_timeout = 5;
return nat;
}
void bsc_nat_set_msc_ip(struct bsc_nat *nat, const char *ip)
{
bsc_replace_string(nat, &nat->msc_ip, ip);
}
struct bsc_connection *bsc_connection_alloc(struct bsc_nat *nat)
{
struct bsc_connection *con = talloc_zero(nat, struct bsc_connection);
if (!con)
return NULL;
con->nat = nat;
write_queue_init(&con->write_queue, 100);
return con;
}
struct bsc_config *bsc_config_alloc(struct bsc_nat *nat, const char *token)
{
struct bsc_config *conf = talloc_zero(nat, struct bsc_config);
if (!conf)
return NULL;
conf->token = talloc_strdup(conf, token);
conf->nr = nat->num_bsc;
conf->nat = nat;
conf->max_endpoints = 32;
INIT_LLIST_HEAD(&conf->lac_list);
llist_add_tail(&conf->entry, &nat->bsc_configs);
++nat->num_bsc;
conf->stats.ctrg = rate_ctr_group_alloc(conf, &bsc_cfg_ctrg_desc, conf->nr);
if (!conf->stats.ctrg) {
talloc_free(conf);
return NULL;
}
return conf;
}
void bsc_config_free(struct bsc_config *cfg)
{
rate_ctr_group_free(cfg->stats.ctrg);
}
void bsc_config_add_lac(struct bsc_config *cfg, int _lac)
{
struct bsc_lac_entry *lac;
llist_for_each_entry(lac, &cfg->lac_list, entry)
if (lac->lac == _lac)
return;
lac = talloc_zero(cfg, struct bsc_lac_entry);
if (!lac) {
LOGP(DNAT, LOGL_ERROR, "Failed to allocate.\n");
return;
}
lac->lac = _lac;
llist_add_tail(&lac->entry, &cfg->lac_list);
}
void bsc_config_del_lac(struct bsc_config *cfg, int _lac)
{
struct bsc_lac_entry *lac;
llist_for_each_entry(lac, &cfg->lac_list, entry)
if (lac->lac == _lac) {
llist_del(&lac->entry);
talloc_free(lac);
return;
}
}
int bsc_config_handles_lac(struct bsc_config *cfg, int lac_nr)
{
struct bsc_lac_entry *entry;
llist_for_each_entry(entry, &cfg->lac_list, entry)
if (entry->lac == lac_nr)
return 1;
return 0;
}
void sccp_connection_destroy(struct sccp_connections *conn)
{
LOGP(DNAT, LOGL_DEBUG, "Destroy 0x%x <-> 0x%x mapping for con %p\n",
sccp_src_ref_to_int(&conn->real_ref),
sccp_src_ref_to_int(&conn->patched_ref), conn->bsc);
bsc_mgcp_dlcx(conn);
llist_del(&conn->list_entry);
talloc_free(conn);
}
struct bsc_connection *bsc_nat_find_bsc(struct bsc_nat *nat, struct msgb *msg, int *lac_out)
{
struct bsc_connection *bsc;
int data_length;
const uint8_t *data;
struct tlv_parsed tp;
int i = 0;
*lac_out = -1;
if (!msg->l3h || msgb_l3len(msg) < 3) {
LOGP(DNAT, LOGL_ERROR, "Paging message is too short.\n");
return NULL;
}
tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 3, msgb_l3len(msg) - 3, 0, 0);
if (!TLVP_PRESENT(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST)) {
LOGP(DNAT, LOGL_ERROR, "No CellIdentifier List inside paging msg.\n");
return NULL;
}
data_length = TLVP_LEN(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST);
data = TLVP_VAL(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST);
/* No need to try a different BSS */
if (data[0] == CELL_IDENT_BSS) {
return NULL;
} else if (data[0] != CELL_IDENT_LAC) {
LOGP(DNAT, LOGL_ERROR, "Unhandled cell ident discrminator: %d\n", data[0]);
return NULL;
}
/* Currently we only handle one BSC */
for (i = 1; i < data_length - 1; i += 2) {
unsigned int _lac = ntohs(*(unsigned int *) &data[i]);
*lac_out = _lac;
llist_for_each_entry(bsc, &nat->bsc_connections, list_entry) {
if (!bsc->cfg)
continue;
if (!bsc->authenticated)
continue;
if (!bsc_config_handles_lac(bsc->cfg, _lac))
continue;
return bsc;
}
}
return NULL;
}
int bsc_write_mgcp(struct bsc_connection *bsc, const uint8_t *data, unsigned int length)
{
struct msgb *msg;
if (length > 4096 - 128) {
LOGP(DINP, LOGL_ERROR, "Can not send message of that size.\n");
return -1;
}
msg = msgb_alloc_headroom(4096, 128, "to-bsc");
if (!msg) {
LOGP(DINP, LOGL_ERROR, "Failed to allocate memory for BSC msg.\n");
return -1;
}
/* copy the data */
msg->l3h = msgb_put(msg, length);
memcpy(msg->l3h, data, length);
return bsc_write(bsc, msg, IPAC_PROTO_MGCP_OLD);
}
int bsc_write(struct bsc_connection *bsc, struct msgb *msg, int proto)
{
return bsc_do_write(&bsc->write_queue, msg, proto);
}
int bsc_do_write(struct write_queue *queue, struct msgb *msg, int proto)
{
/* prepend the header */
ipaccess_prepend_header(msg, proto);
return bsc_write_msg(queue, msg);
}
int bsc_write_msg(struct write_queue *queue, struct msgb *msg)
{
if (write_queue_enqueue(queue, msg) != 0) {
LOGP(DINP, LOGL_ERROR, "Failed to enqueue the write.\n");
msgb_free(msg);
return -1;
}
return 0;
}
int bsc_nat_lst_check_allow(struct bsc_nat_acc_lst *lst, const char *mi_string)
{
struct bsc_nat_acc_lst_entry *entry;
llist_for_each_entry(entry, &lst->fltr_list, list) {
if (!entry->imsi_allow)
continue;
if (regexec(&entry->imsi_allow_re, mi_string, 0, NULL, 0) == 0)
return 0;
}
return 1;
}
static int lst_check_deny(struct bsc_nat_acc_lst *lst, const char *mi_string)
{
struct bsc_nat_acc_lst_entry *entry;
llist_for_each_entry(entry, &lst->fltr_list, list) {
if (!entry->imsi_deny)
continue;
if (regexec(&entry->imsi_deny_re, mi_string, 0, NULL, 0) == 0)
return 0;
}
return 1;
}
/* apply white/black list */
static int auth_imsi(struct bsc_connection *bsc, const char *mi_string)
{
/*
* Now apply blacklist/whitelist of the BSC and the NAT.
* 1.) Allow directly if the IMSI is allowed at the BSC
* 2.) Reject if the IMSI is not allowed at the BSC
* 3.) Reject if the IMSI not allowed at the global level.
* 4.) Allow directly if the IMSI is allowed at the global level
*/
struct bsc_nat_acc_lst *nat_lst = NULL;
struct bsc_nat_acc_lst *bsc_lst = NULL;
bsc_lst = bsc_nat_acc_lst_find(bsc->nat, bsc->cfg->acc_lst_name);
nat_lst = bsc_nat_acc_lst_find(bsc->nat, bsc->nat->acc_lst_name);
if (bsc_lst) {
/* 1. BSC allow */
if (bsc_nat_lst_check_allow(bsc_lst, mi_string) == 0)
return 1;
/* 2. BSC deny */
if (lst_check_deny(bsc_lst, mi_string) == 0) {
LOGP(DNAT, LOGL_ERROR,
"Filtering %s by imsi_deny on bsc nr: %d.\n", mi_string, bsc->cfg->nr);
rate_ctr_inc(&bsc_lst->stats->ctr[ACC_LIST_BSC_FILTER]);
return -2;
}
}
/* 3. NAT deny */
if (nat_lst) {
if (lst_check_deny(nat_lst, mi_string) == 0) {
LOGP(DNAT, LOGL_ERROR,
"Filtering %s by nat imsi_deny on bsc nr: %d.\n", mi_string, bsc->cfg->nr);
rate_ctr_inc(&nat_lst->stats->ctr[ACC_LIST_NAT_FILTER]);
return -3;
}
}
return 1;
}
static int _cr_check_loc_upd(struct bsc_connection *bsc,
uint8_t *data, unsigned int length,
char **imsi)
{
uint8_t mi_type;
struct gsm48_loc_upd_req *lu;
char mi_string[GSM48_MI_SIZE];
if (length < sizeof(*lu)) {
LOGP(DNAT, LOGL_ERROR,
"LU does not fit. Length is %d \n", length);
return -1;
}
lu = (struct gsm48_loc_upd_req *) data;
mi_type = lu->mi[0] & GSM_MI_TYPE_MASK;
/*
* We can only deal with the IMSI. This will fail for a phone that
* will send the TMSI of a previous network to us.
*/
if (mi_type != GSM_MI_TYPE_IMSI)
return 0;
gsm48_mi_to_string(mi_string, sizeof(mi_string), lu->mi, lu->mi_len);
*imsi = talloc_strdup(bsc, mi_string);
return auth_imsi(bsc, mi_string);
}
static int _cr_check_cm_serv_req(struct bsc_connection *bsc,
uint8_t *data, unsigned int length,
int *con_type, char **imsi)
{
static const uint32_t classmark_offset =
offsetof(struct gsm48_service_request, classmark);
char mi_string[GSM48_MI_SIZE];
uint8_t mi_type;
int rc;
struct gsm48_service_request *req;
/* unfortunately in Phase1 the classmark2 length is variable */
if (length < sizeof(*req)) {
LOGP(DNAT, LOGL_ERROR,
"CM Serv Req does not fit. Length is %d\n", length);
return -1;
}
req = (struct gsm48_service_request *) data;
if (req->cm_service_type == 0x8)
*con_type = NAT_CON_TYPE_SSA;
rc = gsm48_extract_mi((uint8_t *) &req->classmark,
length - classmark_offset, mi_string, &mi_type);
if (rc < 0) {
LOGP(DNAT, LOGL_ERROR, "Failed to parse the classmark2/mi. error: %d\n", rc);
return -1;
}
/* we have to let the TMSI or such pass */
if (mi_type != GSM_MI_TYPE_IMSI)
return 0;
*imsi = talloc_strdup(bsc, mi_string);
return auth_imsi(bsc, mi_string);
}
static int _cr_check_pag_resp(struct bsc_connection *bsc,
uint8_t *data, unsigned int length,
char **imsi)
{
struct gsm48_pag_resp *resp;
char mi_string[GSM48_MI_SIZE];
uint8_t mi_type;
if (length < sizeof(*resp)) {
LOGP(DNAT, LOGL_ERROR, "PAG RESP does not fit. Length was %d.\n", length);
return -1;
}
resp = (struct gsm48_pag_resp *) data;
if (gsm48_paging_extract_mi(resp, length, mi_string, &mi_type) < 0) {
LOGP(DNAT, LOGL_ERROR, "Failed to extract the MI.\n");
return -1;
}
/* we need to let it pass for now */
if (mi_type != GSM_MI_TYPE_IMSI)
return 0;
*imsi = talloc_strdup(bsc, mi_string);
return auth_imsi(bsc, mi_string);
}
static int _dt_check_id_resp(struct bsc_connection *bsc,
uint8_t *data, unsigned int length,
struct sccp_connections *con)
{
char mi_string[GSM48_MI_SIZE];
uint8_t mi_type;
int ret;
if (length < 2) {
LOGP(DNAT, LOGL_ERROR, "mi does not fit.\n");
return -1;
}
if (data[0] < length - 1) {
LOGP(DNAT, LOGL_ERROR, "mi length too big.\n");
return -2;
}
mi_type = data[1] & GSM_MI_TYPE_MASK;
gsm48_mi_to_string(mi_string, sizeof(mi_string), &data[1], data[0]);
if (mi_type != GSM_MI_TYPE_IMSI)
return 0;
ret = auth_imsi(bsc, mi_string);
con->imsi_checked = 1;
con->imsi = talloc_strdup(con, mi_string);
return ret;
}
/* 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 tlv_parsed tp;
struct gsm48_hdr *hdr48;
int hdr48_len;
int len;
uint8_t msg_type;
*con_type = NAT_CON_TYPE_NONE;
*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);
msg_type = hdr48->msg_type & 0xbf;
if (hdr48->proto_discr == GSM48_PDISC_MM &&
msg_type == GSM48_MT_MM_LOC_UPD_REQUEST) {
*con_type = NAT_CON_TYPE_LU;
return _cr_check_loc_upd(bsc, &hdr48->data[0], hdr48_len - sizeof(*hdr48), imsi);
} else if (hdr48->proto_discr == GSM48_PDISC_MM &&
msg_type == GSM48_MT_MM_CM_SERV_REQ) {
*con_type = NAT_CON_TYPE_CM_SERV_REQ;
return _cr_check_cm_serv_req(bsc, &hdr48->data[0],
hdr48_len - sizeof(*hdr48),
con_type, imsi);
} else if (hdr48->proto_discr == GSM48_PDISC_RR &&
msg_type == GSM48_MT_RR_PAG_RESP) {
*con_type = NAT_CON_TYPE_PAG_RESP;
return _cr_check_pag_resp(bsc, &hdr48->data[0], hdr48_len - sizeof(*hdr48), imsi);
} else {
/* We only want to filter the above, let other things pass */
*con_type = NAT_CON_TYPE_OTHER;
return 0;
}
}
struct gsm48_hdr *bsc_unpack_dtap(struct bsc_nat_parsed *parsed,
struct msgb *msg, uint32_t *len)
{
/* gsm_type is actually the size of the dtap */
*len = parsed->gsm_type;
if (*len < msgb_l3len(msg) - 3) {
LOGP(DNAT, LOGL_ERROR, "Not enough space for DTAP.\n");
return NULL;
}
if (*len < sizeof(struct gsm48_hdr)) {
LOGP(DNAT, LOGL_ERROR, "GSM48 header does not fit.\n");
return NULL;
}
msg->l4h = &msg->l3h[3];
return (struct gsm48_hdr *) msg->l4h;
}
int bsc_nat_filter_dt(struct bsc_connection *bsc, struct msgb *msg,
struct sccp_connections *con, struct bsc_nat_parsed *parsed)
{
uint32_t len;
uint8_t msg_type;
struct gsm48_hdr *hdr48;
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;
msg_type = hdr48->msg_type & 0xbf;
if (hdr48->proto_discr == GSM48_PDISC_MM &&
msg_type == GSM48_MT_MM_ID_RESP) {
return _dt_check_id_resp(bsc, &hdr48->data[0], len - sizeof(*hdr48), con);
} else {
return 0;
}
}
void bsc_parse_reg(void *ctx, regex_t *reg, char **imsi, int argc, const char **argv)
{
if (*imsi) {
talloc_free(*imsi);
*imsi = NULL;
}
regfree(reg);
if (argc > 0) {
*imsi = talloc_strdup(ctx, argv[0]);
regcomp(reg, argv[0], 0);
}
}
static const char *con_types [] = {
[NAT_CON_TYPE_NONE] = "n/a",
[NAT_CON_TYPE_LU] = "Location Update",
[NAT_CON_TYPE_CM_SERV_REQ] = "CM Serv Req",
[NAT_CON_TYPE_PAG_RESP] = "Paging Response",
[NAT_CON_TYPE_SSA] = "Supplementar Service Activation",
[NAT_CON_TYPE_LOCAL_REJECT] = "Local Reject",
[NAT_CON_TYPE_OTHER] = "Other",
};
const char *bsc_con_type_to_string(int type)
{
return con_types[type];
}
struct bsc_nat_acc_lst *bsc_nat_acc_lst_find(struct bsc_nat *nat, const char *name)
{
struct bsc_nat_acc_lst *lst;
if (!name)
return NULL;
llist_for_each_entry(lst, &nat->access_lists, list)
if (strcmp(lst->name, name) == 0)
return lst;
return NULL;
}
struct bsc_nat_acc_lst *bsc_nat_acc_lst_get(struct bsc_nat *nat, const char *name)
{
struct bsc_nat_acc_lst *lst;
lst = bsc_nat_acc_lst_find(nat, name);
if (lst)
return lst;
lst = talloc_zero(nat, struct bsc_nat_acc_lst);
if (!lst) {
LOGP(DNAT, LOGL_ERROR, "Failed to allocate access list");
return NULL;
}
/* TODO: get the index right */
lst->stats = rate_ctr_group_alloc(lst, &bsc_cfg_acc_list_desc, 0);
if (!lst->stats) {
talloc_free(lst);
return NULL;
}
INIT_LLIST_HEAD(&lst->fltr_list);
lst->name = talloc_strdup(lst, name);
llist_add_tail(&lst->list, &nat->access_lists);
return lst;
}
void bsc_nat_acc_lst_delete(struct bsc_nat_acc_lst *lst)
{
llist_del(&lst->list);
rate_ctr_group_free(lst->stats);
talloc_free(lst);
}
struct bsc_nat_acc_lst_entry *bsc_nat_acc_lst_entry_create(struct bsc_nat_acc_lst *lst)
{
struct bsc_nat_acc_lst_entry *entry;
entry = talloc_zero(lst, struct bsc_nat_acc_lst_entry);
if (!entry)
return NULL;
llist_add_tail(&entry->list, &lst->fltr_list);
return entry;
}
int bsc_nat_msc_is_connected(struct bsc_nat *nat)
{
return nat->msc_con->is_connected;
}
static const int con_to_ctr[] = {
[NAT_CON_TYPE_NONE] = -1,
[NAT_CON_TYPE_LU] = BCFG_CTR_CON_TYPE_LU,
[NAT_CON_TYPE_CM_SERV_REQ] = BCFG_CTR_CON_CMSERV_RQ,
[NAT_CON_TYPE_PAG_RESP] = BCFG_CTR_CON_PAG_RESP,
[NAT_CON_TYPE_SSA] = BCFG_CTR_CON_SSA,
[NAT_CON_TYPE_LOCAL_REJECT] = -1,
[NAT_CON_TYPE_OTHER] = BCFG_CTR_CON_OTHER,
};
int bsc_conn_type_to_ctr(struct sccp_connections *conn)
{
return con_to_ctr[conn->con_type];
}
int bsc_write_cb(struct bsc_fd *bfd, struct msgb *msg)
{
int rc;
rc = write(bfd->fd, msg->data, msg->len);
if (rc != msg->len)
LOGP(DNAT, LOGL_ERROR, "Failed to write message to the BSC.\n");
return rc;
}
/**
* Rewrite non global numbers... according to rules based on the IMSI
*/
struct msgb *bsc_nat_rewrite_setup(struct bsc_nat *nat, struct msgb *msg, struct bsc_nat_parsed *parsed, const char *imsi)
{
struct tlv_parsed tp;
struct gsm48_hdr *hdr48;
uint32_t len;
uint8_t msg_type;
unsigned int payload_len;
struct gsm_mncc_number called;
struct msg_entry *entry;
char *new_number = NULL;
struct msgb *out, *sccp;
uint8_t *outptr;
const uint8_t *msgptr;
int sec_len;
if (!imsi || strlen(imsi) < 5)
return msg;
if (!nat->num_rewr)
return msg;
/* only care about DTAP messages */
if (parsed->bssap != BSSAP_MSG_DTAP)
return msg;
if (!parsed->dest_local_ref)
return msg;
hdr48 = bsc_unpack_dtap(parsed, msg, &len);
if (!hdr48)
return msg;
msg_type = hdr48->msg_type & 0xbf;
if (hdr48->proto_discr != GSM48_PDISC_CC ||
msg_type != GSM48_MT_CC_SETUP)
return msg;
/* decode and rewrite the message */
payload_len = len - sizeof(*hdr48);
tlv_parse(&tp, &gsm48_att_tlvdef, hdr48->data, payload_len, 0, 0);
/* no number, well let us ignore it */
if (!TLVP_PRESENT(&tp, GSM48_IE_CALLED_BCD))
return msg;
memset(&called, 0, sizeof(called));
gsm48_decode_called(&called,
TLVP_VAL(&tp, GSM48_IE_CALLED_BCD) - 1);
/* check if it looks international and stop */
if (called.plan != 1)
return msg;
if (called.type == 1)
return msg;
if (strncmp(called.number, "00", 2) == 0)
return msg;
/* need to find a replacement and then fix it */
llist_for_each_entry(entry, &nat->num_rewr->entry, list) {
regex_t reg;
regmatch_t matches[2];
if (entry->mcc[0] != '*' && strncmp(entry->mcc, imsi, 3) != 0)
continue;
if (entry->mnc[0] != '*' && strncmp(entry->mnc, imsi + 3, 2) != 0)
continue;
if (entry->text[0] == '+') {
LOGP(DNAT, LOGL_ERROR,
"Plus is not allowed in the number");
continue;
}
/* We have an entry for the IMSI. Need to match now */
if (regcomp(&reg, entry->option, REG_EXTENDED) != 0) {
LOGP(DNAT, LOGL_ERROR,
"Regexp '%s' is not valid.\n", entry->option);
continue;
}
/* this regexp matches... */
if (regexec(&reg, called.number, 2, matches, 0) == 0 &&
matches[1].rm_eo != -1)
new_number = talloc_asprintf(msg, "%s%s",
entry->text,
&called.number[matches[1].rm_so]);
regfree(&reg);
if (new_number)
break;
}
if (!new_number) {
LOGP(DNAT, LOGL_DEBUG, "No IMSI match found, returning message.\n");
return msg;
}
if (strlen(new_number) > sizeof(called.number)) {
LOGP(DNAT, LOGL_ERROR, "Number is too long for structure.\n");
talloc_free(new_number);
return msg;
}
/*
* Need to create a new message now based on the old onew
* with a new number. We can sadly not patch this in place
* so we will need to regenerate it.
*/
out = msgb_alloc_headroom(4096, 128, "changed-setup");
if (!out) {
LOGP(DNAT, LOGL_ERROR, "Failed to allocate.\n");
talloc_free(new_number);
return msg;
}
/* copy the header */
outptr = msgb_put(out, sizeof(*hdr48));
memcpy(outptr, hdr48, sizeof(*hdr48));
/* copy everything up to the number */
sec_len = TLVP_VAL(&tp, GSM48_IE_CALLED_BCD) - 2 - &hdr48->data[0];
outptr = msgb_put(out, sec_len);
memcpy(outptr, &hdr48->data[0], sec_len);
/* create the new number */
if (strncmp(new_number, "00", 2) == 0) {
called.type = 1;
strncpy(called.number, new_number + 2, sizeof(called.number));
} else {
strncpy(called.number, new_number, sizeof(called.number));
}
gsm48_encode_called(out, &called);
/* copy thre rest */
msgptr = TLVP_VAL(&tp, GSM48_IE_CALLED_BCD) +
TLVP_LEN(&tp, GSM48_IE_CALLED_BCD);
sec_len = payload_len - (msgptr - &hdr48->data[0]);
outptr = msgb_put(out, sec_len);
memcpy(outptr, msgptr, sec_len);
/* wrap with DTAP, SCCP, then IPA. TODO: Stop copying */
gsm0808_prepend_dtap_header(out, 0);
sccp = sccp_create_dt1(parsed->dest_local_ref, out->data, out->len);
if (!sccp) {
LOGP(DNAT, LOGL_ERROR, "Failed to allocate.\n");
talloc_free(new_number);
talloc_free(out);
return msg;
}
ipaccess_prepend_header(sccp, IPAC_PROTO_SCCP);
/* give up memory, we are done */
talloc_free(new_number);
/* the parsed hangs off from msg but it needs to survive */
talloc_steal(sccp, parsed);
msgb_free(msg);
msgb_free(out);
out = NULL;
return sccp;
}
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