[SR-Users] dialog module: in-early-dialog requests / race conditions

[Ovidiu Sas]

On Tue, Jun 22, 2010 at 12:27 PM, Timo Reimann <timo.reimann at 1und1.de> wrote:
> Hello,
>
> I have two issues related to dialog module state keeping/logging that
> caught my attention today:
>
> 1.) The module considers requests routed in early (but not yet
> confirmed) dialogs to be bogus, as can be seen from a few lines of state
> machine code in dlg_hash.c:
>
> http://git.sip-router.org/cgi-bin/gitweb.cgi?p=sip-router;a=blob;f=modules_k/dialog/dlg_hash.c;h=6aba716c2423cec4402e3be4b55d532d45eabbfa;hb=HEAD#l722
>
> In the logs, it shows up something like this:
>
> CRITICAL:dialog:log_next_state_dlg: bogus event 8 in state 2 for dlg
> 0x7f9f237ffff8 [2901:1286709577] with clid '<Call-ID>' and tags '<caller
> tag>' '<callee tag, always empty>'
>
> I believe that such in-early-dialog requests should not trigger
> bogus-event log messages as they look fine from a standard's point of view.

If this means adding the DLG_STATE_EARLY to the switch, then it should be fine.


> 2.) Various race conditions may generate log messages such as following
> when DID mode is enabled:
>
> WARNING:dialog:dlg_onroute: unable to find dialog for <REQUEST TYPE>
> with route param 'faf.f69e7b4' [4015:79161711]
>
> Observed REQUEST TYPEs at our site were "BYE" when BYE requests were
> transmitted by both caller and callee at roughly the same time due to
> user behavior; and "PRACK" when a PRACK was received by the UAS after a
> 486 (Busy Here)/ACK pair of messages was already exchanged between the
> UAS and the proxy. In both cases, the associated dialog had already been
> destroyed when another request was received.
>
> My suggestion is to lower the log level for this kind of message because
> it can simply happen too often but doesn't affect proper dialog handling.

The proper fix here would be to extend the lifetime of a dialog in
deleted state and absorb any late in-dialog requests.
If we just lower the log level, we don't know if it's a valid warning
log or a bogus one.


> Feedback?
>
>
> Cheers,
>
> --Timo
>
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