[MMUSIC] What goes into c= line address when FQDN is used for the default candidate?

Roman Shpount <roman@telurix.com> Fri, 01 February 2019 00:24 UTC

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From: Roman Shpount <roman@telurix.com>
Date: Thu, 31 Jan 2019 19:24:32 -0500
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Subject: [MMUSIC] What goes into c= line address when FQDN is used for the default candidate?
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Hi All,

I wanted to see if it was ever decided if c= line should contain IN IP4 or
IN IP6 when default ICE candidate address contains FQDN.

For instance, in the following SDP:

m=audio 59372 UDP/TLS/RTP/SAVPF 0
*c=IN IP6 3557773f-5f01-46a4-aa14-54ab35b3d778.local *
a=rtcp:9 IN IP4 0.0.0.0
a=candidate:1962264367 1 udp 2122260223
3557773f-5f01-46a4-aa14-54ab35b3d778.local 59372 typ host
a=ice-ufrag:3iia
a=ice-pwd:HMo0mGLq8nYb9pfnG/nH3pNI
a=rtcp-mux

Is it correct to use "c=IN IP6 3557773f-5f01-46a4-aa14-54ab35b3d778.local "
or should it be "c=IN IP4 3557773f-5f01-46a4-aa14-54ab35b3d778.local"?

Was this choice ever recorded in any specification?

How does this work for dual stack hosts where MDNS will have both types of
entries?

Was it ever decided if FQDN are legal in candidate-address? They are
allowed in ABNF but I cannot find any specifications on how they are
supposed to be resolved and if they result in single candidate or multiple
if FQDN has multiple A and AAAA records.

Regards,
_____________
Roman Shpount