[Partysip-dev] late ACK discarding behaviour

[stefanfritzsche]

Hello,

First of all: thanks for writing partysip.

I have a problem with the "late ack"-discarding behavior
of partysip. I tried to set up a test-environment with two
subnets, like:
                             UDP-
                _  ___+---- bridge ---+_  ___
               / \/   \       |       / \/   \
SIP-UA #1 ----|Subnet 1|      |      |Subnet 2|---- SIP-UA #2
               \______/       |       \______/
                      +---- Proxy ----+
                      
I want the SIP-proxy to observe all call-dependend SIP-messages,
whereon a partysip-plugin configures the UDP-bridge dynamically
to allow RTP-traversal.
The plugin will also translate the RTP-IP:ports of the SDP-blocks
to the ones used by the UDP-bridge.

Since there is no pysical or logical connection between both
subnets, except the partysip-proxy and the udp-bridge, there is
no way to exchange SIP-message directly between both SIP-UAs.

The problem is, that partysip discards incoming ACK-Requests,
after a typical INVITE-OK-session-setup.

("core module: This is a late ACK to discard!" in
psp_core_handle_incoming_message_as_statefull_only()
in psp_core3.c)

Partysip handles all other messages (like BYE, BYE-OK etc.),
but discards the ACK in between (correctly, I know).

Is there a possibility to allow the traversal of such ACKs through
partysip (like a config-switch or something else) ?


thanks in advance
Stefan Fritzsche

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