Service names

[richardschneider]

• All services must be in the '.local' domain (see DNS names #67)
• Change the service name from _ipfs-discovery._udp to ipfs
• IPv6 support (see Parse AAAA records as well #1)
• Don't wait interval for a query to begin (see mDNS discovery should start announcing right away go-libp2p#256)

[richardschneider]

@diasdavid had to make changes to the tests, please review them.

Also, how to add AppVeyor CI?

[daviddias]

@richardschneider wanna fix the test then?

[richardschneider]

I thought about it and could not come up with a test. How does one prove that something will not happen?

[daviddias]

You can stop and wait "two intervals" to make sure that indeed no more broadcasts happen.

[richardschneider]

Done

[richardschneider]

@diasdavid RTM

[lidel]

@richardschneider Hi! There is ongoing work on mDNS API for browser extensions and ipfs.local came up.

Is there a technical reason why this change was done, or was it just pure aesthetics? :)

Change the service name from _ipfs-discovery._udp to ipfs

Problem I: ipfs.local does not seem to follow DNS-SD spec (https://tools.ietf.org/html/rfc6763#section-7) which expects _ipfs._tcp.local for TCP and _ipfs._udp.local [sic!] for everything else.
This breaks things, as we can't reuse Firefox code compatible with mentioned spec.

Problem II: go version seems to be using _ipfs-discovery._udp, which breaks mDNS interop between go and js versions:
https://github.com/libp2p/go-libp2p/blob/f5e43430a1d0f4c1af97338537f3c9b0c7442354/p2p/discovery/mdns.go#L24

See mozilla/libdweb#7 (comment) for more details.

cc @jacobheun

[richardschneider]

@lidel MDNS does not require DNS-SD nor does DNS-SD require MDNS. However, they can work togther.

I was wrong to use _ipfs.local it should be ipfs._tcp.local, thus making it comply with DNS-SD.

DNS-SD also requires a SRV and TXT resource record and expects A and/or AAAA records.

[lidel]

@richardschneider If we can comply with DNS-SD then we should, as it makes it more interoperable with how things work in Firefox and other tools.

I was going to PR to fix this, but not sure what value should we switch to.
go-ipfs is using _ipfs-discovery._udp.local, shouldn't we use the same?

[richardschneider]

Let's move this discussion over to libp2p/libp2p#28.

The current consensus is _ipfs._upd.local.