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sccp_scoc: Fix remote PC not assigned preventing RSLD to be sent in st WAIT_CONN_CONF 

Scenario: RUA Connect triggers SCCP CR towards peer, and we move to
CONN_PEND_OUT state where we expect to receive CC.
However, if some timer (like X31) times out before we receive CC (eg
because CC takes a long time to come), we end up in state
WAIT_CONN_CONF.

In that state, according to Figure C.2/Q.714 (sheet 2 of 7), among other
possibilite we wait for CC, and if it arrives, we send an RLSD to the
peer to inform him that we released the conn, and wait
for the peer to ack the RLSD, then release all state.

Given the scenario above, scoc_fsm_wait_conn_conf() was not assigning
the received OPC from the CC to the conn->remote_pc (unlike
scoc_fsm_conn_pend_out() which does it properly). As a result, when
trying to send teh RLSD it would fail and never transmit RLSD, taking
then a long time to release through T(rel) (10-20 seconds), and probably
longer in the peer (T(iar) or similar?).

Rua Connect triggers tx of SCCP CC:
Received SCCP User Primitive (N-CONNECT.request)
XUA_AS(as-clnt-msc-0)[0x55f11c7df980]{AS_ACTIVE}: Received Event AS-TRANSFER.req //Tx CC
SCCP-SCOC(929)[0x55f11c909c90]{IDLE}: State change to CONN_PEND_OUT (no timeout)
...
X31 timeout triggers state change:
map_sccp(...-SCCP-929)[0x55f11c909820]{wait_cc}: Timeout of X31
SCCP-SCOC(929)[0x55f11c909c90]{CONN_PEND_OUT}: Received Event N-DISCONNECT.req
SCCP-SCOC(929)[0x55f11c909c90]{CONN_PEND_OUT}: State change to WAIT_CONN_CONF (no timeout)
...
CC arrives, but conn_remote_pc is not properly assigned and tx of RLSD fails:
SCCP-SCOC(929)[0x55f11c909c90]{WAIT_CONN_CONF}: Received Event RCOC-CONNECT_CONFIRM.ind
MTP-TRANSFER.req from SCCP without DPC?!? called=RI=0 // PROBLEM HERE!!!!
SCCP-SCOC(929)[0x55f11c909c90]{WAIT_CONN_CONF}: State change to DISCONN_PEND (no timeout)
...
SCCP-SCOC(929)[0x55f11c909c90]{DISCONN_PEND}: Received Event T(rel)_expired

Related: SYS#6616
Change-Id: I9f9f78c92dd95f38af7b03037e60a1c993d7e5b0
This commit is contained in:
Pau Espin 2023-10-30 17:21:54 +01:00 committed by pespin
parent 427c462484
commit 42ed1bf15d
1 changed files with 7 additions and 0 deletions
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7
src/sccp_scoc.c
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@ -1160,6 +1160,13 @@ static void scoc_fsm_wait_conn_conf(struct osmo_fsm_inst *fi, uint32_t event, vo
conn_stop_connect_timer(conn);
/* associate rem ref to conn */
conn->remote_ref = xua_msg_get_u32(xua, SUA_IEI_SRC_REF);
/* 3.1.4.2 The node sending the CC message (identified
* by the parameter OPC contained in the
* MTP-TRANSFER.indication primitive which conveyed the
* CC message [plus the MTP-SAP instance]) is associated
* with the connection section. */
conn->remote_pc = xua->mtp.opc;
/* released to SCRC */
xua_gen_relre_and_send(conn, conn->release_cause, NULL);
/* start rel timer */