/* (C) 2017 by sysmocom s.f.m.c. GmbH
* All Rights Reserved
*
* Author: Philipp Maier
*
* 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 .
*
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
/* A pointer to a list with all involved MSCs
* (a copy of the pointer location submitted with osmo_bsc_sigtran_init() */
static struct llist_head *msc_list;
#define RESET_INTERVAL 1 /* sek */
#define SCCP_MSG_MAXSIZE 1024
#define CS7_POINTCODE_DEFAULT_OFFSET 2
/* Internal list with connections we currently maintain. This
* list is of type struct osmo_bsc_sccp_con */
static LLIST_HEAD(active_connections);
/* The SCCP stack will not assign connection IDs to us automatically, we
* will do this ourselves using a counter variable, that counts one up
* for every new connection */
static uint32_t conn_id_counter;
/* Helper function to Check if the given connection id is already assigned */
static struct osmo_bsc_sccp_con *get_bsc_conn_by_conn_id(int conn_id)
{
conn_id &= 0xFFFFFF;
struct osmo_bsc_sccp_con *bsc_con;
llist_for_each_entry(bsc_con, &active_connections, entry) {
if (bsc_con->conn_id == conn_id)
return bsc_con;
}
return NULL;
}
/* Pick a free connection id */
static int pick_free_conn_id(const struct bsc_msc_data *msc)
{
int conn_id = conn_id_counter;
int i;
for (i = 0; i < 0xFFFFFF; i++) {
conn_id++;
conn_id &= 0xFFFFFF;
if (get_bsc_conn_by_conn_id(conn_id) == false) {
conn_id_counter = conn_id;
return conn_id;
}
}
return -1;
}
/* Send reset to MSC */
static void osmo_bsc_sigtran_tx_reset(const struct bsc_msc_data *msc)
{
struct osmo_ss7_instance *ss7;
struct msgb *msg;
ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
OSMO_ASSERT(ss7);
LOGP(DMSC, LOGL_NOTICE, "Sending RESET to MSC: %s\n", osmo_sccp_addr_name(ss7, &msc->a.msc_addr));
msg = gsm0808_create_reset();
osmo_sccp_tx_unitdata_msg(msc->a.sccp_user, &msc->a.bsc_addr,
&msc->a.msc_addr, msg);
}
/* Send reset-ack to MSC */
void osmo_bsc_sigtran_tx_reset_ack(const struct bsc_msc_data *msc)
{
struct osmo_ss7_instance *ss7;
struct msgb *msg;
OSMO_ASSERT(msc);
ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
OSMO_ASSERT(ss7);
LOGP(DMSC, LOGL_NOTICE, "Sending RESET ACK to MSC: %s\n", osmo_sccp_addr_name(ss7, &msc->a.msc_addr));
msg = gsm0808_create_reset_ack();
osmo_sccp_tx_unitdata_msg(msc->a.sccp_user, &msc->a.bsc_addr,
&msc->a.msc_addr, msg);
}
/* Find an MSC by its sigtran point code */
static struct bsc_msc_data *get_msc_by_addr(const struct osmo_sccp_addr *msc_addr)
{
struct osmo_ss7_instance *ss7;
struct bsc_msc_data *msc;
llist_for_each_entry(msc, msc_list, entry) {
if (memcmp(msc_addr, &msc->a.msc_addr, sizeof(*msc_addr)) == 0)
return msc;
}
ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
OSMO_ASSERT(ss7);
LOGP(DMSC, LOGL_ERROR, "Unable to find MSC data under address: %s\n", osmo_sccp_addr_name(ss7, msc_addr));
return NULL;
}
/* Send data to MSC, use the connection id which MSC it is */
static int handle_data_from_msc(int conn_id, struct msgb *msg)
{
struct osmo_bsc_sccp_con *bsc_con = get_bsc_conn_by_conn_id(conn_id);
int rc = -EINVAL;
if (bsc_con) {
msg->l3h = msgb_l2(msg);
rc = bsc_handle_dt(bsc_con, msg, msgb_l2len(msg));
} else
LOGP(DMSC, LOGL_NOTICE, "incoming data from unknown connection id: %i\n", conn_id);
return rc;
}
/* Sent unitdata to MSC, use the point code to determine which MSC it is */
static int handle_unitdata_from_msc(const struct osmo_sccp_addr *msc_addr, struct msgb *msg,
const struct osmo_sccp_user *scu)
{
struct osmo_ss7_instance *ss7;
struct bsc_msc_data *msc = get_msc_by_addr(msc_addr);
int rc = -EINVAL;
if (msc) {
msg->l3h = msgb_l2(msg);
rc = bsc_handle_udt(msc, msg, msgb_l2len(msg));
} else {
ss7 = osmo_sccp_get_ss7(osmo_sccp_get_sccp(scu));
OSMO_ASSERT(ss7);
LOGP(DMSC, LOGL_NOTICE, "incoming unitdata data from unknown remote address: %s\n",
osmo_sccp_addr_name(ss7, msc_addr));
}
return rc;
}
/* Callback function, called by the SSCP stack when data arrives */
static int sccp_sap_up(struct osmo_prim_hdr *oph, void *_scu)
{
struct osmo_scu_prim *scu_prim = (struct osmo_scu_prim *)oph;
struct osmo_sccp_user *scu = _scu;
struct osmo_bsc_sccp_con *bsc_con;
int rc = 0;
switch (OSMO_PRIM_HDR(&scu_prim->oph)) {
case OSMO_PRIM(OSMO_SCU_PRIM_N_UNITDATA, PRIM_OP_INDICATION):
/* Handle inbound UNITDATA */
DEBUGP(DMSC, "N-UNITDATA.ind(%s)\n", osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
rc = handle_unitdata_from_msc(&scu_prim->u.unitdata.calling_addr, oph->msg, scu);
break;
case OSMO_PRIM(OSMO_SCU_PRIM_N_CONNECT, PRIM_OP_INDICATION):
/* Handle (Reject) inbound connections */
DEBUGP(DMSC, "N-CONNECT.ind(X->%u)\n", scu_prim->u.connect.conn_id);
LOGP(DMSC, LOGL_DEBUG, "Rejecting inbound SCCP connection...\n");
rc = osmo_sccp_tx_disconn(scu, scu_prim->u.connect.conn_id, &scu_prim->u.connect.called_addr, 0);
break;
case OSMO_PRIM(OSMO_SCU_PRIM_N_CONNECT, PRIM_OP_CONFIRM):
/* Handle outbound connection confirmation */
if (msgb_l2len(oph->msg) > 0) {
DEBUGP(DMSC, "N-CONNECT.cnf(%u, %s)\n", scu_prim->u.connect.conn_id,
osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
rc = handle_data_from_msc(scu_prim->u.connect.conn_id, oph->msg);
} else
DEBUGP(DRANAP, "N-CONNECT.cnf(%u)\n", scu_prim->u.connect.conn_id);
break;
case OSMO_PRIM(OSMO_SCU_PRIM_N_DATA, PRIM_OP_INDICATION):
/* Handle incoming connection oriented data */
DEBUGP(DMSC, "N-DATA.ind(%u, %s)\n", scu_prim->u.data.conn_id,
osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
/* Incoming data is a sign of a vital connection */
bsc_con = get_bsc_conn_by_conn_id(scu_prim->u.disconnect.conn_id);
if (bsc_con)
a_reset_conn_success(bsc_con->msc->a.reset);
rc = handle_data_from_msc(scu_prim->u.data.conn_id, oph->msg);
break;
case OSMO_PRIM(OSMO_SCU_PRIM_N_DISCONNECT, PRIM_OP_INDICATION):
/* indication of disconnect */
if (msgb_l2len(oph->msg) > 0) {
DEBUGP(DMSC, "N-DISCONNECT.ind(%u, %s, cause=%i)\n", scu_prim->u.disconnect.conn_id,
osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)), scu_prim->u.disconnect.cause);
handle_data_from_msc(scu_prim->u.disconnect.conn_id, oph->msg);
} else
DEBUGP(DRANAP, "N-DISCONNECT.ind(%u, cause=%i)\n", scu_prim->u.disconnect.conn_id,
scu_prim->u.disconnect.cause);
bsc_con = get_bsc_conn_by_conn_id(scu_prim->u.disconnect.conn_id);
if (bsc_con) {
/* We might have a connectivity problem. Maybe we need to go
* through the reset procedure again? */
if (scu_prim->u.disconnect.cause == 0)
a_reset_conn_fail(bsc_con->msc->a.reset);
rc = osmo_bsc_sigtran_del_conn(bsc_con);
}
break;
default:
LOGP(DMSC, LOGL_ERROR, "Unhandled SIGTRAN primitive: %u:%u\n", oph->primitive, oph->operation);
break;
}
msgb_free(oph->msg);
return rc;
}
/* Allocate resources to make a new connection oriented sigtran connection
* (not the connection ittself!) */
enum bsc_con osmo_bsc_sigtran_new_conn(struct gsm_subscriber_connection *conn, struct bsc_msc_data *msc)
{
struct osmo_ss7_instance *ss7;
struct osmo_bsc_sccp_con *bsc_con;
int conn_id;
OSMO_ASSERT(conn);
OSMO_ASSERT(msc);
ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
OSMO_ASSERT(ss7);
LOGP(DMSC, LOGL_NOTICE, "Initializing resources for new SIGTRAN connection to MSC: %s...\n",
osmo_sccp_addr_name(ss7, &msc->a.msc_addr));
if (a_reset_conn_ready(msc->a.reset) == false) {
LOGP(DMSC, LOGL_ERROR, "MSC is not connected. Dropping.\n");
return BSC_CON_REJECT_NO_LINK;
}
if (!bsc_grace_allow_new_connection(conn->bts->network, conn->bts)) {
LOGP(DMSC, LOGL_NOTICE, "BSC in grace period. No new connections.\n");
return BSC_CON_REJECT_RF_GRACE;
}
bsc_con = talloc_zero(conn->bts, struct osmo_bsc_sccp_con);
if (!bsc_con) {
LOGP(DMSC, LOGL_ERROR, "Failed to allocate new SIGTRAN connection.\n");
return BSC_CON_NO_MEM;
}
bsc_con->msc = msc;
bsc_con->conn = conn;
llist_add_tail(&bsc_con->entry, &active_connections);
conn->sccp_con = bsc_con;
/* Pick a free connection id */
conn_id = pick_free_conn_id(msc);
if (conn_id < 0)
return BSC_CON_REJECT_NO_LINK;
bsc_con->conn_id = conn_id;
LOGP(DMSC, LOGL_NOTICE, "Allocated new connection id: %i\n", conn_id);
return BSC_CON_SUCCESS;
}
/* Open a new connection oriented sigtran connection */
int osmo_bsc_sigtran_open_conn(const struct osmo_bsc_sccp_con *conn, struct msgb *msg)
{
struct osmo_ss7_instance *ss7;
struct bsc_msc_data *msc;
int conn_id;
int rc;
OSMO_ASSERT(conn);
OSMO_ASSERT(msg);
OSMO_ASSERT(conn->msc);
msc = conn->msc;
if (a_reset_conn_ready(msc->a.reset) == false) {
LOGP(DMSC, LOGL_ERROR, "MSC is not connected. Dropping.\n");
return -EINVAL;
}
conn_id = conn->conn_id;
ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
OSMO_ASSERT(ss7);
LOGP(DMSC, LOGL_NOTICE, "Opening new SIGTRAN connection (id=%i) to MSC: %s\n", conn_id,
osmo_sccp_addr_name(ss7, &msc->a.msc_addr));
rc = osmo_sccp_tx_conn_req_msg(msc->a.sccp_user, conn_id, &msc->a.bsc_addr,
&msc->a.msc_addr, msg);
return rc;
}
/* Send data to MSC */
int osmo_bsc_sigtran_send(const struct osmo_bsc_sccp_con *conn, struct msgb *msg)
{
struct osmo_ss7_instance *ss7;
int conn_id;
int rc;
struct bsc_msc_data *msc;
OSMO_ASSERT(conn);
OSMO_ASSERT(msg);
OSMO_ASSERT(conn->msc);
msc = conn->msc;
/* Log the type of the message we are sending. This is just
* informative, do not stop if detecting the type fails */
if (msg->len >= 3) {
switch (msg->data[0]) {
case BSSAP_MSG_BSS_MANAGEMENT:
LOGP(DMSC, LOGL_INFO, "Tx MSC %s\n", gsm0808_bssmap_name(msg->data[2]));
break;
case BSSAP_MSG_DTAP:
LOGP(DMSC, LOGL_INFO, "Tx MSC DTAP\n");
break;
default:
LOGP(DMSC, LOGL_ERROR, "Tx MSC (unknwon message type)\n");
}
} else
LOGP(DMSC, LOGL_ERROR, "Tx MSC (message too short)\n");
if (a_reset_conn_ready(msc->a.reset) == false) {
LOGP(DMSC, LOGL_ERROR, "MSC is not connected. Dropping.\n");
return -EINVAL;
}
conn_id = conn->conn_id;
ss7 = osmo_ss7_instance_find(msc->a.cs7_instance);
OSMO_ASSERT(ss7);
LOGP(DMSC, LOGL_DEBUG, "Sending connection (id=%i) oriented data to MSC: %s (%s)\n",
conn_id, osmo_sccp_addr_name(ss7, &msc->a.msc_addr), osmo_hexdump(msg->data, msg->len));
rc = osmo_sccp_tx_data_msg(msc->a.sccp_user, conn_id, msg);
return rc;
}
/* Delete a connection from the list with open connections
* (called by osmo_bsc_api.c on failing open connections and
* locally, when a connection is closed by the MSC */
int osmo_bsc_sigtran_del_conn(struct osmo_bsc_sccp_con *conn)
{
if (!conn)
return 0;
if (conn->conn) {
LOGP(DMSC, LOGL_ERROR,
"sccp connection (id=%i) not cleared (gsm subscriber connection still active) -- forcefully clearing it now!\n",
conn->conn_id);
bsc_subscr_con_free(conn->conn);
conn->conn = NULL;
/* This bahaviour might be caused by a bad connection. Maybe we
* will have to go through the reset procedure again */
a_reset_conn_fail(conn->msc->a.reset);
}
/* Remove mgcp context if existant */
if (conn->mgcp_ctx)
mgcp_free_ctx(conn->mgcp_ctx);
llist_del(&conn->entry);
talloc_free(conn);
return 0;
}
/* Send an USSD notification in case we loose the connection to the MSC */
static void bsc_notify_msc_lost(const struct osmo_bsc_sccp_con *conn)
{
struct gsm_subscriber_connection *subscr_conn;
/* Check if sccp conn is still present */
if (!conn)
return;
subscr_conn = conn->conn;
/* send USSD notification if string configured and conn->data is set */
if (!subscr_conn)
return;
/* check for config string */
if (!conn->msc->ussd_msc_lost_txt)
return;
if (conn->msc->ussd_msc_lost_txt[0] == '\0')
return;
/* send USSD notification */
bsc_send_ussd_notify(subscr_conn, 1, subscr_conn->sccp_con->msc->ussd_msc_lost_txt);
bsc_send_ussd_release_complete(subscr_conn);
}
/* Close all open sigtran connections and channels */
void osmo_bsc_sigtran_reset(const struct bsc_msc_data *msc)
{
struct osmo_bsc_sccp_con *conn;
struct osmo_bsc_sccp_con *conn_temp;
OSMO_ASSERT(msc);
/* Close all open connections */
llist_for_each_entry_safe(conn, conn_temp, &active_connections, entry) {
/* We only may close connections which actually belong to this
* MSC. All other open connections are left untouched */
if (conn->msc == msc) {
/* Notify active connection users via USSD that the MSC is down */
bsc_notify_msc_lost(conn);
/* Take down all occopied RF channels */
if (conn->conn)
gsm0808_clear(conn->conn);
/* Disconnect all Sigtran connections */
osmo_sccp_tx_disconn(msc->a.sccp_user, conn->conn_id, &msc->a.bsc_addr, 0);
/* Delete subscriber connection */
osmo_bsc_sigtran_del_conn(conn);
}
}
}
/* Callback function: Close all open connections */
static void osmo_bsc_sigtran_reset_cb(const void *priv)
{
struct bsc_msc_data *msc = (struct bsc_msc_data*) priv;
/* Shut down all ongoing traffic */
osmo_bsc_sigtran_reset(msc);
/* Send reset to MSC */
osmo_bsc_sigtran_tx_reset(msc);
}
/* Default point-code to be used as local address (BSC) */
#define BSC_DEFAULT_PC "0.23.3"
/* Default point-code to be used as remote address (MSC) */
#define MSC_DEFAULT_PC "0.23.1"
/* Initalize osmo sigtran backhaul */
int osmo_bsc_sigtran_init(struct llist_head *mscs)
{
bool free_attempt_used = false;
bool fail_on_next_invalid_cfg = false;
struct bsc_msc_data *msc;
char msc_name[32];
uint32_t default_pc;
OSMO_ASSERT(mscs);
msc_list = mscs;
llist_for_each_entry(msc, msc_list, entry) {
snprintf(msc_name, sizeof(msc_name), "msc-%u", msc->nr);
LOGP(DMSC, LOGL_NOTICE, "Initializing SCCP connection to MSC %s\n", msc_name);
/* Check if the VTY could determine a valid CS7 instance,
* use safe default in case none is set */
if (msc->a.cs7_instance_valid == false) {
msc->a.cs7_instance = 0;
if (fail_on_next_invalid_cfg)
goto fail_auto_cofiguration;
free_attempt_used = true;
}
LOGP(DMSC, LOGL_NOTICE, "CS7 Instance identifier, A-Interface: %u\n", msc->a.cs7_instance);
/* Pre-Check if there is an ss7 instance present */
if (osmo_ss7_instance_find(msc->a.cs7_instance) == NULL) {
if (fail_on_next_invalid_cfg)
goto fail_auto_cofiguration;
free_attempt_used = true;
}
/* SS7 Protocol stack */
default_pc = osmo_ss7_pointcode_parse(NULL, BSC_DEFAULT_PC);
msc->a.sccp =
osmo_sccp_simple_client_on_ss7_id(msc, msc->a.cs7_instance, msc_name, default_pc,
OSMO_SS7_ASP_PROT_M3UA, 0, NULL, 0, NULL);
if (!msc->a.sccp)
return -EINVAL;
/* If unset, use default local SCCP address */
if (!msc->a.bsc_addr.presence)
osmo_sccp_local_addr_by_instance(&msc->a.bsc_addr, msc->a.sccp,
OSMO_SCCP_SSN_BSSAP);
if (!osmo_sccp_check_addr(&msc->a.bsc_addr, OSMO_SCCP_ADDR_T_SSN | OSMO_SCCP_ADDR_T_PC)) {
LOGP(DMSC, LOGL_ERROR,
"(%s) A-interface: invalid local (BSC) SCCP address: %s\n",
msc_name, osmo_sccp_inst_addr_name(msc->a.sccp, &msc->a.bsc_addr));
return -EINVAL;
}
/* If unset, use default SCCP address for the MSC */
if (!msc->a.msc_addr.presence)
osmo_sccp_make_addr_pc_ssn(&msc->a.msc_addr,
osmo_ss7_pointcode_parse(NULL, MSC_DEFAULT_PC),
OSMO_SCCP_SSN_BSSAP);
if (!osmo_sccp_check_addr(&msc->a.msc_addr, OSMO_SCCP_ADDR_T_SSN | OSMO_SCCP_ADDR_T_PC)) {
LOGP(DMSC, LOGL_ERROR,
"(%s) A-interface: invalid remote (MSC) SCCP address: %s\n",
msc_name, osmo_sccp_inst_addr_name(msc->a.sccp, &msc->a.msc_addr));
return -EINVAL;
}
LOGP(DMSC, LOGL_NOTICE, "(%s) A-interface: local (BSC) SCCP address: %s\n",
msc_name, osmo_sccp_inst_addr_name(msc->a.sccp, &msc->a.bsc_addr));
LOGP(DMSC, LOGL_NOTICE, "(%s) A-interface: remote (MSC) SCCP address: %s\n",
msc_name, osmo_sccp_inst_addr_name(msc->a.sccp, &msc->a.msc_addr));
/* Bind SCCP user */
msc->a.sccp_user = osmo_sccp_user_bind(msc->a.sccp, msc_name, sccp_sap_up, msc->a.bsc_addr.ssn);
if (!msc->a.sccp_user)
return -EINVAL;
/* Start MSC-Reset procedure */
msc->a.reset = a_reset_alloc(msc, msc_name, osmo_bsc_sigtran_reset_cb, msc);
if (!msc->a.reset)
return -EINVAL;
/* If we have detected that the SS7 configuration of the MSC we have just initalized
* was incomplete or completely missing, we can not tolerate another incomplete
* configuration. The reson for this is that we do only specify exactly one default
* pointcode pair. We also specify localhost as default IP-Address. If we have wanted
* to support multiple MSCs with automatic configuration we would be forced to invent
* a complex ruleset how to allocate the pointcodes and respective IP-Addresses.
* Furthermore, the situation where a single BSC is connected to multiple MSCs
* is a very rare situation anyway. In this case we expect the user to experienced
* enough to create a valid SS7/CS7 VTY configuration that does not lack any
* components */
if (free_attempt_used)
fail_on_next_invalid_cfg = true;
}
return 0;
fail_auto_cofiguration:
LOGP(DMSC, LOGL_ERROR,
"A-interface: More than one invalid/inclomplete configuration detected, unable to revover - check config file!\n");
return -EINVAL;
}