[asterisk-bugs] [JIRA] (ASTERISK-27365) [patch] chan_sip: Crypto attribute not last but first on SDP media level.

[Alexander Traud (JIRA)]

Alexander Traud created ASTERISK-27365:
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             Summary: [patch] chan_sip: Crypto attribute not last but first on SDP media level.
                 Key: ASTERISK-27365
                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-27365
             Project: Asterisk
          Issue Type: Bug
      Security Level: None
          Components: Channels/chan_sip/Interoperability, Channels/chan_sip/SRTP
            Reporter: Alexander Traud
            Severity: Minor
         Attachments: sdp_media_level_required_at_begin.patch

Some VoIP/SIP implementations have a limit of 32 attributes on the media level in SDP. You hit this limitation, if you allow a lot of audio codecs. Without Compact Headers enabled (see ASTERISK-26932), each audio codec creates a rtpmap attribute. Some codecs even create a fmtp attribute. If you have more than 32, affected devices like the desktop phone Gigaset DE900 IP Pro (firmware [02.01.00|https://teamwork.gigaset.com/gigawiki/pages/viewpage.action?pageId=372408431]) ignore all further attributes on that specific media level. If a sRTP a:crypto= is sent as last attribute, the Gigaset is not aware of the crypto and establishes a non-encrypted call.

In the channel driver {{chan_sip}}, any crypto attribute is sent last. In {{chan_pjsip}} those attributes are send first. The attached patch changes {{chan_sip}} to match {{chan_pjsip}}.



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