[bssap] Start to queue messages to the BTS and to the MSC

For the MSC we need to queue GSM04.08 messages until the
SCCP connection is  confirmed to be open and then can send
the stored messages. The queue is limited to 10 messages
at which point new ones will be dropped. Currently the
only messages we get are measurement indication messages
but it is better to be safe than sorry.

The SCCP messages are sent as soon as the connection
is considered established and then no queueing happens
any more. While replacing sccp_connection_write calls
various memory leaks has been fixed.

For the MS we might have received a DTAP and need to do
an operation that requires a roundtrip and want to send
wait until this has happened. The two scenerios are sending
a SMS to the phone that requires to do something special
for the different SAPI. Currently it is assumed that
only one SAPI=0 -> SAPI=3 change happen during the connection.

For the first SAPI != 0 we will send the rll_ request
and then wait for the timeout or confirmation. In case
of timeout a SAPI "n" reject is sent and in case of
success the queue is getting emptied.

1 files changed, 7 insertions, 0 deletions

diff --git a/openbsc/include/openbsc/gsm_data.h b/openbsc/include/openbsc/gsm_data.h
index 8a9446a5e..d01973e4b 100644
--- a/openbsc/include/openbsc/gsm_data.h
+++ b/openbsc/include/openbsc/gsm_data.h
@@ -121,6 +121,13 @@ struct bss_sccp_connection_data {
 	struct gsm_lchan *lchan;
 	struct sccp_connection *sccp;
 	int ciphering_handled : 1;
+
+	/* Queue SCCP and GSM0408 messages */
+	struct llist_head gsm_queue;
+	unsigned int gsm_queue_size;
+
+	struct llist_head sccp_queue;
+	unsigned int sccp_queue_size;
 };
 
 #define sccp_get_lchan(data_ctx) ((struct bss_sccp_connection_data *)data_ctx)->lchan