Disconnect calls with incompatible channel types / modes
In case both TCH/H and TCH/F or different codecs are configured and
internal MNCC handler is used we might end up in a situation where call
legs with incompatible channel types or codecs would be connected
resulting in a broken audio. Disconnect such calls with appropriate
error message.
Fixes: OS#1663
diff --git a/openbsc/src/libmsc/gsm_04_08.c b/openbsc/src/libmsc/gsm_04_08.c
index 7b78d48..05cb886 100644
--- a/openbsc/src/libmsc/gsm_04_08.c
+++ b/openbsc/src/libmsc/gsm_04_08.c
@@ -1600,6 +1600,7 @@
struct gsm_bts *bts = lchan->ts->trx->bts;
struct gsm_bts *remote_bts = remote_lchan->ts->trx->bts;
enum gsm_chan_t lt = lchan->type, rt = remote_lchan->type;
+ enum gsm48_chan_mode lm = lchan->tch_mode, rm = remote_lchan->tch_mode;
int rc;
DEBUGP(DCC, "Setting up TCH map between (bts=%u,trx=%u,ts=%u,%s) and "
@@ -1614,6 +1615,22 @@
return -EINVAL;
}
+ if (lt != rt) {
+ LOGP(DCC, LOGL_ERROR, "Cannot patch through call with different"
+ " channel types: local = %s, remote = %s\n",
+ get_value_string(gsm_chan_t_names, lt),
+ get_value_string(gsm_chan_t_names, rt));
+ return -EBADSLT;
+ }
+
+ if (lm != rm) {
+ LOGP(DCC, LOGL_ERROR, "Cannot patch through call with different"
+ " channel modes: local = %s, remote = %s\n",
+ get_value_string(gsm48_chan_mode_names, lm),
+ get_value_string(gsm48_chan_mode_names, rm));
+ return -EMEDIUMTYPE;
+ }
+
// todo: map between different bts types
switch (bts->type) {
case GSM_BTS_TYPE_NANOBTS:
@@ -1851,6 +1868,30 @@
}
+/* disconnect both calls from the bridge */
+static inline void disconnect_bridge(struct gsm_network *net,
+ struct gsm_mncc_bridge *bridge, int err)
+{
+ struct gsm_trans *trans0 = trans_find_by_callref(net, bridge->callref[0]);
+ struct gsm_trans *trans1 = trans_find_by_callref(net, bridge->callref[1]);
+ struct gsm_mncc mx_rel;
+ if (!trans0 || !trans1)
+ return;
+
+ DEBUGP(DCC, "Failed to bridge TCH for calls %x <-> %x :: %s \n",
+ trans0->callref, trans1->callref, strerror(err));
+
+ memset(&mx_rel, 0, sizeof(struct gsm_mncc));
+ mncc_set_cause(&mx_rel, GSM48_CAUSE_LOC_INN_NET,
+ GSM48_CC_CAUSE_CHAN_UNACCEPT);
+
+ mx_rel.callref = trans0->callref;
+ gsm48_cc_tx_disconnect(trans0, &mx_rel);
+
+ mx_rel.callref = trans1->callref;
+ gsm48_cc_tx_disconnect(trans1, &mx_rel);
+}
+
static void gsm48_start_cc_timer(struct gsm_trans *trans, int current,
int sec, int micro)
{
@@ -3221,7 +3262,10 @@
/* handle special messages */
switch(msg_type) {
case MNCC_BRIDGE:
- return tch_bridge(net, arg);
+ rc = tch_bridge(net, arg);
+ if (rc < 0)
+ disconnect_bridge(net, arg, -rc);
+ return rc;
case MNCC_FRAME_DROP:
return tch_recv_mncc(net, data->callref, 0);
case MNCC_FRAME_RECV: