Re: [MMUSIC] FQDN support in ice-sip-sdp
Suhas Nandakumar <suhasietf@gmail.com> Wed, 10 April 2019 05:40 UTC
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From: Suhas Nandakumar <suhasietf@gmail.com>
Date: Tue, 09 Apr 2019 22:40:23 -0700
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To: Roman Shpount <roman@telurix.com>
Cc: mmusic WG <mmusic@ietf.org>, Flemming Andreasen <fandreas@cisco.com>, Christer Holmberg <christer.holmberg@ericsson.com>
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Subject: Re: [MMUSIC] FQDN support in ice-sip-sdp
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Hi Roman & Chairs Thanks for the text I feel we should restrict the scope for FQDN resolution to just one address for this specification. Future specifications may define handling of multiple resolutions (or DNS64/NAT64 ) scenarios If others are fine with this, I would want to get an updated draft and move this forward Please let me know Thanks Suhas On Wed, Apr 3, 2019 at 9:47 AM Roman Shpount <roman@telurix.com> wrote: > Reposting er Flemming's advise as a new thread: > > Hi All, > > I have created a pull request to ice-sip-sdp ( > https://github.com/suhasHere/ice-sip-sdp/pull/1), which among other > things added back support for FQDN to ice-sip-sdp. > > In order to do this, I've done the following: > > 1. I have changed "IP address" to "connection address" throughout the > document whenever address in c= line or ICE candidate attribute is > mentioned. I hope this is not controversial since it matches ABNF. > > 2. I have changed the definition of <connection-address> > > Old: > > <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. > > > New: > > <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 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 both AAAA record (assuming the agent supports IPv6), > and using an A > record (assuming the agent supports IPv4). If, and only if, the DNS query > returns > only one IP address it is then used for the remainder of ICE processing. > If DNS query > returned more then one result, including situation where single IPv4 and > single IPv6 > results are returned, an agent MUST ignore the candidate. Handling of > multiple DNS > results for a candidate can be defined in the future specification. If > candidate > with FQDN <connection-address> is the default destination/candidate, the > 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. > > > > This change reflects what was discussed previously.. I am, personally, > less then happy with this change. My biggest issue is requirement for FQDN > to resolve to a single address or be ignored. In practice, this is > problematic when things like DNS64/NAT64 are used. When DNS64 is used, even > when FQDN was supposed to only resolve to IPv4, AAAA will also return > result which will point to the NAT64 gateway. Based on the current > language, this will result in candidate being ignored even though it should > work with either IPv4 or IPv6 address. Most immediately, this will mean > FQDN resolving to IPv4 will be ignored on a lot of mobile networks. > > I have also added language that defines what is supposed to be placed in > c= line when default candidate is an FQDN candidate. What happens when FQDN > resolution result and address family in c= line do not match was not > specified. > > To summarize, this no worse then RFC 5245, but still fairly messy. I see > two possible ways to clean this up: > > a. Add a candidate extension which specifies candidate address type, > something like addrtype which can be set to "inipv4" or "inipv6". If IP > address is used and it does not match the addrtype candidate extension, > this candidate is ignored. When FQDN is used, it is resolved using A DNS > request when addrtype is inipv4 or not present and using AAAA DNS request > when addrtype is inipv6. Address family in c= line, when FQDN is a default > candidate must be IN IPV4 if addrtype is inipv4 or not present, and must be > IP IPV6 if addrtype is inipv6 > > b. Specify that during ICE nomination all DNS resolution results for the > candidate should be added as separate candidates to the candidate list. > This is likely to cause more problems then option a. One of these problems > that I see is priority values for these candidates. Candidate priorities > should be different for all of them but only one value is specified in SDP > candidate attribute. > > In order to simplify tracking changes, I will write different emails about > other changes I've done in the pull request. > > I have also included people who shown previous interest in this topic. > Please let me know if I need to cross post to rtcweb and ice WG. > > Thank you for your attention, > _____________ > Roman Shpount > _______________________________________________ > mmusic mailing list > mmusic@ietf.org > https://www.ietf.org/mailman/listinfo/mmusic >
- [MMUSIC] FQDN support in ice-sip-sdp Roman Shpount
- Re: [MMUSIC] FQDN support in ice-sip-sdp Suhas Nandakumar
- Re: [MMUSIC] FQDN support in ice-sip-sdp Roman Shpount
- Re: [MMUSIC] FQDN support in ice-sip-sdp Christer Holmberg
- Re: [MMUSIC] FQDN support in ice-sip-sdp Roman Shpount
- Re: [MMUSIC] FQDN support in ice-sip-sdp Suhas Nandakumar
- Re: [MMUSIC] FQDN support in ice-sip-sdp Christer Holmberg
- Re: [MMUSIC] FQDN support in ice-sip-sdp Christer Holmberg
- Re: [MMUSIC] FQDN support in ice-sip-sdp Roman Shpount
- Re: [MMUSIC] FQDN support in ice-sip-sdp Roman Shpount
- Re: [MMUSIC] FQDN support in ice-sip-sdp Christer Holmberg
- Re: [MMUSIC] FQDN support in ice-sip-sdp Christer Holmberg
- Re: [MMUSIC] FQDN support in ice-sip-sdp Roman Shpount
- Re: [MMUSIC] FQDN support in ice-sip-sdp Christer Holmberg
- Re: [MMUSIC] FQDN support in ice-sip-sdp Roman Shpount
- Re: [MMUSIC] FQDN support in ice-sip-sdp Christer Holmberg
- Re: [MMUSIC] FQDN support in ice-sip-sdp Roman Shpount
- Re: [MMUSIC] FQDN support in ice-sip-sdp Christer Holmberg
- Re: [MMUSIC] FQDN support in ice-sip-sdp Suhas Nandakumar
- Re: [MMUSIC] FQDN support in ice-sip-sdp Christer Holmberg
- Re: [MMUSIC] FQDN support in ice-sip-sdp Roman Shpount
- Re: [MMUSIC] FQDN support in ice-sip-sdp Christer Holmberg