Re: [MMUSIC] FQDN Support Final Vote

Personally, I like the suggested text from Christer and Roman because it
explicitly states that if FQDNs are not supported then the candidates must
be ignored.

On Tue, May 21, 2019 at 8:26 AM Suhas Nandakumar <suhasietf@gmail.com>
wrote:

> Hi All
>
>   Below i have included 4 flavors of suggested text for FQDN support in
> ice-sip-sdp.  Let's agree on one and go with it (even it doesn't make us
> entirely happy).
>
>
> *RFC5245 Version *
> "<connection-address>: is taken from RFC 4566
> <https://tools.ietf.org/html/rfc4566> [RFC4566
> <https://tools.ietf.org/html/rfc4566>]. It is the
>
>       IP address of the candidate, allowing for IPv4 addresses, IPv6 addresses, and fully qualified domain names (FQDNs).  When parsing this field, an agent can differentiate an IPv4 address and an IPv6 address by presence of a colon in its value - the presence of a colon indicates IPv6.  An agent MUST ignore candidate lines that include candidates with IP address versions that are not supported or recognized.  An IP address SHOULD be used, but an FQDN MAY be used in place of an IP address.  In that case, when receiving an offer or answer containing an FQDN in an a=candidate attribute, the FQDN is looked up in the DNS first using an AAAA record (assuming the agent supports IPv6), and if no result is found or the agent only supports IPv4, using an A.  If the DNS query returns more than one IP address, one is chosen, and then used for the remainder of ICE processing.
>
>
> *ice-sip-sdp pre-22 version1*
>
>
> <connection-address>:  is taken from RFC 4566 [RFC4566].  It is the IP address of the candidate.  When parsing this field, an agent can differentiate an IPv4 address and an IPv6 address by presence of a colon in its value -- the presence of a colon indicates IPv6. An agent MUST ignore candidate lines that include candidates with IP address versions that are not supported or recognized.  An IP address SHOULD be used, but an FQDN MAY be used in place of an IP address.  In that case, when receiving an offer or answer containing an FQDN in an a=candidate attribute, the FQDN is looked up in the DNS first using an AAAA record (assuming the agent supports IPv6), and if no result is found or the agent only supports IPv4, using an A record.  The rules from section 6 of [RFC6724] is followed by fixing the source address to be one from the candidate pair to be matched against destination addresses
>
> reported by FQDN, in cases where the DNS query returns more than one IP address.
>
>
> *ice-sip-sdp current version*
>
> <connection-address>:  is taken from RFC 4566 [RFC4566].  It is the
>       IP address of the candidate.  When parsing this field, an agent
>       can differentiate an IPv4 address and an IPv6 address by presence
>       of a colon in its value -- the presence of a colon indicates IPv6.
>       An agent MUST ignore candidate lines that include candidates with
>       IP address versions that are not supported or recognized.  An IP
>       address SHOULD be used, but an FQDN MAY be used in place of an IP
>       address.  In that case, when receiving an offer or answer
>       containing an FQDN in an a=candidate attribute, the FQDN is looked
>       up in the DNS first using an AAAA record (assuming the agent
>       supports IPv6), and if no result is found or the agent only
>       supports IPv4, using an A record.  If a FQDN returns multiple IP
>       addresses an agent MUST only use one of them throughout the
>       duration of the ICE session.  Since an agent does not know whether
>       the peer listens to the chosen IP address and port, it is
>       RECOMMENDED to not use FQDNs that will resolve into multiple IP
>       addresses.
>
>
> *Roman-Christer Version *
>
> <connection-address>: :: is taken from RFC 4566 <<RFC4566>>.. It is the IP
> address of the candidate, allowing for IPv4 addresses, IPv6 addresses,
>
> and fully qualified domain names (FQDNs).  When parsing this field, an
> agent can differentiate  an IPv4 address and an IPv6 address by presence
>
> of a colon in its value - the presence of a colon indicates IPv6.  *An
> agent processing remote candidates MUST ignore candidate lines that include*
>
> *candidates with FQDN or IP address versions that are not supported or
> recognized.  The procedures for handling FQDN candidates, and for agents*
>
> *to indicate support of such procedures, need to be specified in an
> extension specification.* If candidate with FQDN <connection-address> is
> the
>
> default destination/candidate, the "c=" address type MUST be set the IP
> address family for the FQDN DNS resolution result and the "c=" connection
>
> address MUST be set to FQDN. Differences in the "c=" line address family
> and type with FQDN resolution result MUST not cause ICE support
> verification failure.
>
>
>
>
> *My vote is on current version since it is backward compatible with a
> warning that using FQDN is not recommended since it MAY lead to failure.*
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