On 25.10.2022 19:11, Ross McKillop via Users wrote:
I would have expected $socket_in(port) to contain the actual port that
was used (53235) and $socket_in(advertised_port) to contain the port
that is advertised as the listening port for that socket (e.g. 7700) -
however $socket_in(port) contains 7700 and $socket_in(advertised_port)
is null.
Is this the intended behaviour and, if so, is there any way to access
the *actual* destination port that was used (even if it’s ephemeral)?
Any advice anyone can offer would be much appreciated :)
Hey, Ross!
Regarding $socket: there is the READ-ONLY $socket_in [1], concerning the
ingress traffic and $socket_out [2], READ-WRITE and fully optional,
controlling the egress traffic. And an OpenSIPS listener MAY
additionally have an "advertised" component, for scenarios where it's
sitting behind a NAT.
I can't think of many good ways of fetching/printing the ephemeral
source port allocated by the Operating System for a TCP connection:
* Request time: you cannot print it while processing the INVITE since
the source port is not even allocated until you run the very last t_relay()
* Reply time: replies will be routed using topmost Via, so *maybe* you
have a chance at printing this port, by looking at the topmost Via
header (OpenSIPS-generated), using transformations [3]. Even if
OpenSIPS strips this header during loose_route(), you should still have
access to it thanks to the "SIP message lumps" lazy evaluation mechanism.
Still: may I ask why you need the "egress ephemeral source port"
information? Maybe there is an alternative to the problem itself!
[1]: https://opensips.org/Documentation/Script-CoreVar-3-4#socket_in
[2]: https://opensips.org/Documentation/Script-CoreVar-3-4#socket_out
[3]: https://www.opensips.org/Documentation/Script-Tran-3-4
Best regards,
--
Liviu Chircu
www.twitter.com/liviuchircu |www.opensips-solutions.com
OpenSIPS eBootcamp 5-16 Dec |www.opensips.org/training
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