24 Nov
2020
24 Nov
'20
10:20 p.m.
### Description
After updating from 5.3.6 to 5.3.7 Kamailio is no longer increments CSeq for ACK when used
together with UAC module.
Usage scenario:
<pre>
|EP1 | Kamailio | PBX
| ->INVITE -> | |
| <- 407 - | |
| - ACK -> | |
| -> INVITE SDP AUTH-> | |
| <- 100 Trying - | |
| | - INVITE SDP -> |
| | <- 407 - |
| | -> ACK -> |
| | - INVITE SDP AUTH -> |
| | <- 100 Trying - |
| | <- 200 OK - |
| <- 200 OK - | |
| - ACK -> | |
| | - ACK -> |
...
</pre>
Kamailio is configured to use dialog module and calling "dlg_manage();"
UAC module is used to authenticate request on the PBX.
Because of the authentication against the PBX the CSeq is being incremented independently
between Kamailio & PBX.
ACK that is send to the PBX after 200 OK usually is CSeq + 1 from EP1 ACK message.
After update, Cseq is no longer incremented in ACK which cause re-transmission of 200 OK
by the PBX and eventually in 30 sec PBX drops the call because 200 is not being
acknowledged.
Dialog configured as:
modparam("dialog", "dlg_flag", FLD_TRACKDLG)
modparam("dialog", "track_cseq_updates", 1)
modparam("dialog", "dlg_match_mode", 1)
modparam("dialog", "timeout_avp", "$avp(dlgtimeout)")
modparam("dialog", "default_timeout", 43200)
UAC configured as:
modparam("uac", "reg_db_url", DBURL)
modparam("uac", "reg_contact_addr", REG_CONTACT)
modparam("uac", "reg_timer_interval", 10)
modparam("uac",
"restore_from_avp","$avp(original_uri_from)")
modparam("uac", "restore_to_avp","$avp(original_uri_to)")
modparam("uac", "restore_dlg", 1)
modparam("uac", "auth_username_avp","$avp(auser)")
modparam("uac", "auth_password_avp","$avp(apass)")
modparam("uac", "auth_realm_avp","$avp(arealm)")
modparam("uac", "restore_mode","manual")
### Possible Solutions
After reverting this commit a973882b064c758972ce40e9ac3a83440c613be1 CSeq started to
update properly.
"dialog: skip non-INVITE initial request for cseq update processing"
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