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osmo-ttcn3-hacks
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MSC_ConnectionHandler: make as_handover more race robust 

The IPACC and MDCX interaction happens nearly in parallel to the
normal RSL connection that handles the handover, in particular the
channel relase from the old BTS may arrive in between IPACC and MGCP
operations.

- When the channel release arrives, check if MGCP and IPACC
  operations are done (we have seen one MDCX on MGCP and an CRCX
  plus an MDCX on IPACC level)

Change-Id: I207e9ece48ec53f872f82d981435cee7c2d0b094
Related: OS#3396
This commit is contained in:
Philipp Maier 2018-07-18 16:03:00 +02:00 committed by Harald Welte
parent 692c9ee854
commit c1e95c844c
1 changed files with 32 additions and 7 deletions
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39
bsc/MSC_ConnectionHandler.ttcn
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@ -74,6 +74,7 @@ type record MgcpConnState {
/* BTS media state */
type record BtsMediaState {
boolean ipa_crcx_seen,
boolean ipa_mdcx_seen,
uint16_t conn_id,
uint7_t rtp_pt,
HostPort bts,
@ -91,6 +92,7 @@ function f_MediaState_init(inout MediaState g_media, integer nr, HostName bts, H
/* BTS Side */
g_media.bts := {
ipa_crcx_seen := false,
ipa_mdcx_seen := false,
conn_id := nr,
rtp_pt := 0,
bts := {
@ -102,6 +104,7 @@ function f_MediaState_init(inout MediaState g_media, integer nr, HostName bts, H
g_media.bts1 := {
ipa_crcx_seen := false,
ipa_mdcx_seen := false,
conn_id := nr,
rtp_pt := 0,
bts := {
@ -204,7 +207,7 @@ altstep as_Media_ipacc() runs on MSC_ConnHdlr {
oct2int(f_inet_addr(g_media.bts.peer.host)),
g_media.bts.peer.port_nr,
g_media.bts.rtp_pt));
//g_media.bts.ipa_mdcx_seen := true;
g_media.bts.ipa_mdcx_seen := true;
repeat;
}
@ -248,7 +251,7 @@ altstep as_Media_ipacc() runs on MSC_ConnHdlr {
oct2int(f_inet_addr(g_media.bts1.peer.host)),
g_media.bts1.peer.port_nr,
g_media.bts1.rtp_pt));
//g_media.bts1.ipa_mdcx_seen := true;
g_media.bts1.ipa_mdcx_seen := true;
repeat;
}
@ -257,7 +260,7 @@ altstep as_Media_ipacc() runs on MSC_ConnHdlr {
/* altstep for handling of MGCP media related commands. Activated by as_Media() to test
* MGW level media handling */
altstep as_Media_mgw() runs on MSC_ConnHdlr {
altstep as_Media_mgw(boolean norepeat := false) runs on MSC_ConnHdlr {
var MgcpCommand mgcp_cmd;
[] MGCP.receive(tr_CRCX) -> value mgcp_cmd {
@ -290,7 +293,9 @@ altstep as_Media_mgw() runs on MSC_ConnHdlr {
f_mgcp_par_append(mgcp_resp.params, ts_MgcpParSpecEP(g_media.mgcp_ep));
MGCP.send(mgcp_resp);
g_media.mgcp_conn[cid].crcx_seen := g_media.mgcp_conn[cid].crcx_seen + 1;
repeat;
if(norepeat == false) {
repeat;
}
}
[] MGCP.receive(tr_MDCX) -> value mgcp_cmd {
var SDP_Message sdp;
@ -311,7 +316,9 @@ altstep as_Media_mgw() runs on MSC_ConnHdlr {
valueof(ts_SDP_ptime(mgcp_conn.ptime)) } ));
MGCP.send(ts_MDCX_ACK(mgcp_cmd.line.trans_id, mgcp_conn.conn_id, sdp));
g_media.mgcp_conn[cid].mdcx_seen := g_media.mgcp_conn[cid].mdcx_seen + 1;
repeat;
if(norepeat == false) {
repeat;
}
}
}
@ -969,6 +976,7 @@ runs on MSC_ConnHdlr {
type record HandoverState {
/* Assignment related bits */
boolean rr_ho_cmpl_seen,
integer mdcx_seen_before_ho,
boolean handover_done,
RslChannelNr old_chan_nr
};
@ -1004,13 +1012,18 @@ altstep as_handover(inout HandoverState st) runs on MSC_ConnHdlr {
st.old_chan_nr := g_chan_nr;
g_chan_nr := new_chan_nr;
st.rr_ho_cmpl_seen := true;
/* Memorize how many MDCX we have seen before. We need this number to detect
* that we have received the handover related MDCX */
st.mdcx_seen_before_ho := g_media.mgcp_conn[0].mdcx_seen;
repeat;
} else {
setverdict(fail, "Unexpected L3 received", l3);
self.stop;
}
}
[st.rr_ho_cmpl_seen] as_Media();
[st.rr_ho_cmpl_seen] as_Media_ipacc();
[st.rr_ho_cmpl_seen] as_Media_mgw(true);
[st.rr_ho_cmpl_seen] RSL.receive(tr_RSL_REL_REQ(st.old_chan_nr, tr_RslLinkID_DCCH(0))) {
RSL.send(ts_RSL_REL_CONF(st.old_chan_nr, valueof(ts_RslLinkID_DCCH(0))));
repeat;
@ -1020,7 +1033,19 @@ altstep as_handover(inout HandoverState st) runs on MSC_ConnHdlr {
/* unregister for old channel number in RSL emulation */
/* FIXME: Determine TRX NR by ARFCN, instead of hard-coded TRX0! */
f_rslem_unregister(0, st.old_chan_nr);
st.handover_done := true;
/* The channel release must not necessarly be synchronized to the RSL handover
* procedure since those events may happen independently nearly at the same
* time. When we receive the RSL_RF_CHAN_REL command the media negotiation on
* IPACC or MGCP level may be still in progress. In order to make sure that
* we do only stop when we have seen an MDCX on MGCP level and another a CRCX
* as well as an MDCX on IPACC level. */
if (g_media.mgcp_conn[0].mdcx_seen <= st.mdcx_seen_before_ho or
g_media.bts1.ipa_mdcx_seen == false or g_media.bts1.ipa_crcx_seen == false) {
repeat;
} else {
st.handover_done := true;
}
}
}