[asterisk-bugs] [JIRA] (ASTERISK-29237) chan_sip: SDP: m=video is parsed even when disabled.

[Alexander Traud (JIRA)]

     [ https://issues.asterisk.org/jira/browse/ASTERISK-29237?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alexander Traud updated ASTERISK-29237:
---------------------------------------

    Attachment: sidestep_SDP_stream_parsing.patch

> chan_sip: SDP: m=video is parsed even when disabled.
> ----------------------------------------------------
>
>                 Key: ASTERISK-29237
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-29237
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Channels/chan_sip/CodecHandling, Channels/chan_sip/Video
>    Affects Versions: 16.15.1, 18.1.1
>            Reporter: Alexander Traud
>            Severity: Minor
>              Labels: fax, patch
>         Attachments: sidestep_SDP_stream_parsing.patch
>
>
> When videosupport=no is configured, which is the default, the SIP channel driver chan_sip still parses {{m=video}} streams in SDP. The same happens for textsupport=no and {{m=text}}. This is a waste of processor power.
> When videosupport=no, p->vrtp is NULL.
> When textsupport=no, p->trtp is NULL.
> see dialog_initialize_rtp(.) in channels/chan_sip.c
> Furthermore, this always-SDP-parsing complicates the remaining code in process_sdp(.) because for video streams, not only p->vrtp but also vportno and/or vsa must be checked again and again. Same for text streams. Actually, this issue here was found because of two existing issues. Those issues are caused because the states of those three variables are not checked correctly. Those two issues have a higher severity than this issue here.
> *Notes*
> * The attached patch adds this check for audio streams as well. However, with the current source code, p->rtp is never null. Therefore, this check is just for symmetry reasons.
> * The same should be done for image streams based on T.38 FAX (UDPTL). However, code inspection showed that in process_sdp(.), in the part "Setup audio address and port", chan_sip allows no audio but T.38 pass-through without checking p->udptl. It is questionable whether a T.38 session was required before. Nevertheless, because I cannot test this part, the attached patch does not introduce this change for image streams as well.



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