dexter has uploaded this change for review. ( https://gerrit.osmocom.org/9231
Change subject: MSC_ConnectionHandler: check channel mode in f_establish_fully
......................................................................
MSC_ConnectionHandler: check channel mode in f_establish_fully
The helper function f_establish_fully() checks the channel type
for compatibility. If the channel type is compatible with the
desired mode a channel mode modification could be necessary if
the current channel mode is different from the desired channel
mode. However, this is not checked at the momemend. We just
blindly expect a MODE MODIFY message from the BSC and ignore
the cases where the current channel mode and the desired channel
mode already matches up. This is the case if only a signalling
channel is requested with f_establish_fully for example.
- Check if the channel mode of the current channel and the
desired channel mode match up.
- Make sure that the MODE MODIFY from the BSC is only
expected when the channel modes are different.
Change-Id: I9004f299220b01ecea6b2316ba3f913c316947dc
Closes: OS#2762
Related: OS#2936
---
M bsc/MSC_ConnectionHandler.ttcn
1 file changed, 46 insertions(+), 4 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-ttcn3-hacks
refs/changes/31/9231/1
diff --git a/bsc/MSC_ConnectionHandler.ttcn b/bsc/MSC_ConnectionHandler.ttcn
index 991a693..f799bfe 100644
--- a/bsc/MSC_ConnectionHandler.ttcn
+++ b/bsc/MSC_ConnectionHandler.ttcn
@@ -674,6 +674,35 @@
return false;
}
+/* Determine if the channel mode specified within rsl_chan_nr requires a
+ * MODE MODIFY in to match the channel mode specified by given BSSMAP
+ * ChannelType */
+function f_channel_needs_modify(BSSMAP_IE_ChannelType bssmap, RslChannelNr
rsl_chan_nr)
+return boolean {
+
+ var boolean current_signalling := false;
+ var boolean desired_signalling := false;
+
+ select (rsl_chan_nr) {
+ case (t_RslChanNr_SDCCH4(?, ?)) { current_signalling := true; }
+ case (t_RslChanNr_SDCCH8(?, ?)) { current_signalling := true; }
+ }
+
+ if (bssmap.speechOrDataIndicator == '0011'B) {
+ desired_signalling := true;
+ }
+
+ if (current_signalling == desired_signalling) {
+ /* The desired channel mode is equal to the one we currently
+ * have, there is no mode modification needed or expected */
+ return false;
+ } else {
+ /* The desired channel mode and the current channel mode do
+ * not match. A mode modification is required */
+ return true;
+ }
+}
+
/* establish a channel fully, expecting an assignment matching 'exp' */
function f_establish_fully(template (omit) PDU_BSSAP ass_tpl, template
PDU_BSSAP exp_ass_cpl)
runs on MSC_ConnHdlr {
@@ -698,6 +727,7 @@
timer T := 10.0;
var boolean exp_compl :=
ischosen(exp_ass_cpl.pdu.bssmap.assignmentComplete);
var boolean exp_fail :=
ischosen(exp_ass_cpl.pdu.bssmap.assignmentFailure);
+ var boolean exp_modify;
var ExpectCriteria mgcpcrit := {
connid := omit,
endpoint := omit,
@@ -707,10 +737,23 @@
/* if the channel type is SIGNAL, we're not handling a voice call */
if
(ass_cmd.pdu.bssmap.assignmentRequest.channelType.speechOrDataIndicator !=
'0011'B) {
st.voice_call := true;
+ exp_modify := true;
}
+
/* determine if the current channel can support the given service or
not */
if (not
f_channel_compatible(ass_cmd.pdu.bssmap.assignmentRequest.channelType,
g_chan_nr)) {
st.is_assignment := true;
+
+ /* We decided to assign a new channel, so we do not expect
+ * any mode modify messages on RSL */
+ exp_modify := false;
+ } else {
+
+ /* We will continue working with the currently assigned
+ * channel, we must now check if the mode of the current
+ * channel is compatible. If not we expect the BSC to modify
+ * the mode */
+ exp_modify :=
f_channel_needs_modify(ass_cmd.pdu.bssmap.assignmentRequest.channelType,
g_chan_nr);
}
f_create_mgcp_expect(mgcpcrit);
@@ -722,21 +765,20 @@
[st.is_assignment] as_assignment(st);
/* modify related bits */
- [not st.is_assignment] as_modify(st);
+ [not st.is_assignment and exp_modify] as_modify(st);
/* voice call related bits (IPA CRCX/MDCX + MGCP) */
[st.voice_call] as_Media();
/* if we receive exactly what we expected, always return + pass */
- [st.is_assignment and st.assignment_done or
- (not st.is_assignment and st.modify_done)] BSSAP.receive(exp_ass_cpl)
-> value bssap {
+ [st.is_assignment and st.assignment_done or (not st.is_assignment and
(st.modify_done or not exp_modify))] BSSAP.receive(exp_ass_cpl) -> value bssap {
setverdict(pass);
}
[exp_fail] BSSAP.receive(exp_ass_cpl) -> value bssap {
setverdict(pass);
}
[(st.is_assignment and st.assignment_done or
- (not st.is_assignment and st.modify_done)) and
+ (not st.is_assignment and (st.modify_done or not exp_modify))) and
exp_compl] BSSAP.receive(tr_BSSMAP_AssignmentComplete) {
setverdict(fail, "Received non-matching ASSIGNMENT COMPLETE");
}
--
To view, visit https://gerrit.osmocom.org/9231
To unsubscribe, or for help writing mail filters, visit
https://gerrit.osmocom.org/settings
Gerrit-Project: osmo-ttcn3-hacks
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I9004f299220b01ecea6b2316ba3f913c316947dc
Gerrit-Change-Number: 9231
Gerrit-PatchSet: 1
Gerrit-Owner: dexter <pma...@sysmocom.de>
