Cellular Network Infrastructure » OsmoMGW

I have now resumed working on this:

For the problem we have with ptmap I found an elegant fix that won't break the ABI or API. We now can just define multiple occurrences of the same codec in ptmap. In case multiple occurrences are used, then the order must match the order that is used in codecs[].

https://gerrit.osmocom.org/c/osmo-mgw/+/34349 mgcp_client_fsm: allow the same codec multiple times in ptmap [NEW]

For the problem with the codec params we still have to add an array. I have done this now. I also re-defined struct mgcp_codec_param as mgcp_codec_param2 since I think a union makes more sense than the _present logic of the old mgcp_codec_param.

https://gerrit.osmocom.org/c/osmo-mgw/+/34350 mgcp_client_fsm: explain member param in struct mgcp_conn_peer better [NEW]
https://gerrit.osmocom.org/c/osmo-mgw/+/34351 mgcp_client_fsm: fix inconsistent API (param_present, param). [NEW]

(I have not forgotten the approach where we can pass in SDP directly. I will add this in a follow up patch)

I just submitted https://gerrit.osmocom.org/c/osmo-mgw/+/34899 to allow multiple variants of one codec, as an alternative to https://gerrit.osmocom.org/c/osmo-mgw/+/34349, which does the same thing but in another direction. Instead of that patch, it is possible to remove complexity to fix the problem.

I just also submitted an alternative suggestion for https://gerrit.osmocom.org/c/osmo-mgw/+/34351 :
https://gerrit.osmocom.org/c/osmo-mgw/+/34900

It still has some problems in the ttcn3 test suite concerning conversion between OA and BE, so marked WIP.

dexter It would be great to hear what you think of these alternative patches of mine.
I think by submitting my patch, I may inadvertently have rebased your two patches that I took up in my branch.
I hope you agree with those ideas.

I think it is no problem to use 3gpp-ts-101.318. I also don't think that the dot would cause any trouble. It is not used as a separator or anything.

On Tue, Oct 31, 2023 at 10:34:18AM +0000, dexter wrote:

I think it is no problem to use 3gpp-ts-101.318. I also don't think that the dot would cause any trouble. It is not used as a separator or anything.

don't the MGCP and SDP specs contain an EBNF syntax or something like this, which formally defines which
characters are permitted where?

Here is the fmtp definition:
https://www.rfc-editor.org/rfc/rfc8866#name-fmtp-format-parameters

fmtp-value = fmt SP format-specific-params [means "a=fmtp:N <format-specific-params>"]
format-specific-params = byte-string

with

byte-string = 1*(%x01-09/%x0B-0C/%x0E-FF)
;any byte except NUL, CR, or LF

and the further limitation:

Format-specific parameters, semicolon separated, may be any set of parameters required to be conveyed...

Basically total freedom within one line of text, and ';' reserved for separator.
It does not say anything about "foo=bar" assignments, except for the examples.

On Wed, Nov 01, 2023 at 01:28:47AM +0000, neels wrote:

Here is the fmtp definition:
https://www.rfc-editor.org/rfc/rfc8866#name-fmtp-format-parameters

thanks for checking. It's always good to verify rather than making assumptions (the previous
ticket update sounded to me like that was the case).