Using dns-sd with libp2p-mdns #5982
Description
Summary
I am unable to use dns-sd tool with libp2p-mdns. See below for more info.
Expected behavior
I will give an example over another crate, mdns-sd. Suppose we register a service _p2p._udp with our hostname foobar there. Then, we will see ourself with:
$ dns-sd -B _p2p._udp
A/R Flags if Domain Service Type Instance Name
Add 3 11 local. _p2p._udp. foobarWe can then query that service instance as well:
$ dns-sd -Q _p2p._udp.local. PTR
A/R Flags IF Name Type Class Rdata
Add 40000003 11 _p2p._udp.local. PTR IN foobar._p2p._udp.local.We can follow that PTR value to get SRV and TXT records:
# service records
$ dns-sd -Q foobar._p2p._udp.local. SRV
A/R Flags IF Name Type Class Rdata
Add 40000003 1 foobar._p2p._udp.local. SRV IN 0 0 3456 <something-here>
# additional records
$ dns-sd -Q foobar._p2p._udp.local. TXT
A/R Flags IF Name Type Class Rdata
Add 40000003 11 foobar._p2p._udp.local. TXT IN 9 bytes: <some bytes here>Actual behavior
Looking at the chat example, I would expect to how the mDNS implementation responds to the dns-sd tool.
Of course at first nothing appears when we are not running the service:
# see a p2p related service
dns-sd -Q _services._dns-sd._udp.local PTR | grep p2p# or directly query the service name:
dns-sd -Q _p2p._udp.local. PTR Then I do cargo run within the chat example, and we can immediately see some results:
$ dns-sd -Q _services._dns-sd._udp.local PTR | grep p2p
Add 2 12 _services._dns-sd._udp.local. PTR IN _p2p._udp.local.$ dns-sd -Q _p2p._udp.local. PTR
A/R Flags IF Name Type Class Rdata
Add 40000003 12 _p2p._udp.local. PTR IN PJ2Adr3Zp8KKry1ftPa0wckURooHtuaQq9abVx2ZjL.
Add 40000003 12 _p2p._udp.local. PTR IN BtLsbrMhFqOLJxqb4IH91BWuy4PmXIHkJDWZr8VE.
Add 40000003 12 _p2p._udp.local. PTR IN evwca28w1FbzKvilNd3entoeSD2OYf0XZZfC.
Add 40000003 12 _p2p._udp.local. PTR IN akG3qYT6xxTfmEIl8c0akPhB7HeaUb4l86CuW.
Add 40000003 12 _p2p._udp.local. PTR IN hsEIRIw3O9gwZSUAvtoFIG5nVTxHyWpR.
Add 40000002 12 _p2p._udp.local. PTR IN Ip5EpyxGobOBKCgTItmJAK0mRgEoNyNXV.
Add 3 12 _p2p._udp.local. PTR IN 4AEDDykQHCi7lnaZAlhRtOZ2PElE9PENgEouK4HiMRubEhXJK0bMObeGYHr.
Add 2 12 _p2p._udp.local. PTR IN b8Kl6NpZR7HLZqbgYVqHKAV6u2Xwso8Z52fmdmxmXhlzmacyQE.At this point, I couldn't see how I could query the SRV and TXT records as is expected in the standard. Normally we should be able to query those records, like:
dns-sd -Q 4AEDDykQHCi7lnaZAlhRtOZ2PElE9PENgEouK4HiMRubEhXJK0bMObeGYHr. SRV
dns-sd -Q 4AEDDykQHCi7lnaZAlhRtOZ2PElE9PENgEouK4HiMRubEhXJK0bMObeGYHr. TXT but these do not return any response.
When we look at the libp2p mdns spec we also see that we should be able to query with <peer-id>.<service>, but I wasn't able to get any response with that as well.
It also does not respond to dns-sd -B _p2p._udp. with an instance name.
Relevant log output
Possible Solution
Not a solution for this library maybe, but I would love to have info one how one can perhaps integrate the mentioned mdns-sd crate as a Behaviour for libp2p.
Version
0.55.0
Would you like to work on fixing this bug?
Maybe