Identity REST API endpoint returns 0.0.0.0 address

[jakubgs]

Describe the bug
Currently the /eth/v1/node/identity REST API endpoint returns incorrect multiaddress under p2p_addresses:

jakubgs@linux-01.ih-eu-mda1.nimbus.sepolia:~ % c -s 0:9311/eth/v1/node/identity | jq '.data | { p2p_addresses, discovery_addresses }'
{
  "p2p_addresses": [
    "/ip4/0.0.0.0/tcp/9011/p2p/16Uiu2HAmQEmCoEfKQ7ZdPyw1vkMYPLfosfksRUJwssvyDzAosGgm"
  ],
  "discovery_addresses": [
    "/ip4/185.181.230.77/udp/9011/p2p/16Uiu2HAmQEmCoEfKQ7ZdPyw1vkMYPLfosfksRUJwssvyDzAosGgm"
  ]
}

As can be seen the discovery_addresses is correctly using the known public IP address - most probably thanks to the correct value of the --nat=extip:... flag - while p2p_addresses returns 0.0.0.0.

Additional context
Present currently for all 4 main branches:

jakubgs@linux-01.ih-eu-mda1.nimbus.sepolia:~ % for port in $(seq 9311 9314); do c 0:$port/eth/v1/node/identity | jq -c .data.p2p_addresses; done
["/ip4/0.0.0.0/tcp/9011/p2p/16Uiu2HAmQEmCoEfKQ7ZdPyw1vkMYPLfosfksRUJwssvyDzAosGgm"]
["/ip4/0.0.0.0/tcp/9012/p2p/16Uiu2HAm5rcnvjSbXMtzosDnGBsgwi5REfxCNCjeqcYDnHf86XsF"]
["/ip4/0.0.0.0/tcp/9013/p2p/16Uiu2HAmCDZ2qDxdoRYdYGYentnSndWfTYuSSh9jzzK3Qc6QGd1q"]
["/ip4/0.0.0.0/tcp/9014/p2p/16Uiu2HAmGXdiCU2VX9GpuTq3GPm28gBncaBLWEcN8MZaskXcYhYb"]

[cheatfate]

This is libp2p known issue and probably limitation.

[jakubgs]

What do you mean by "limitation"? I'd assume that If it works for discovery it can be made to work for the p2p address.

[cheatfate]

Usually developers prefer to use 0.0.0.0 which forces OS to bound server to all available interfaces. But this comes with limitation that when you will request local address of bound socket you will receive 0.0.0.0:<some port> instead of real interface address. To get this addresses you need to enumerate all the interfaces and bound to their IP addresses manually. But there is no such functionality in nim-libp2p yet, so REST server reports what nim-libp2p provides to it.
And to note that that provided multiaddresses are 100% correct, but i agree this addresses are unusable...

[cheatfate]

By word "limitation" i mean that nim-libp2p developers do not implemented this functionality yet and i have not seen such functionality in plans.

[jakubgs]

To get this addresses you need to enumerate all the interfaces and bound to their IP addresses manually. But there is no such functionality in nim-libp2p yet, so REST server reports what nim-libp2p provides to it.

I though that's what --nat=extip:... is for. To avoid having to guess which interface is the correct one.

[cheatfate]

libp2p should collect its own addresses while talking with other nodes during identify phase. And replace 0.0.0.0 with this addresses.

[jakubgs]

I see, well, then I guess the only sensible thing is to patch it after querying the API since fixing this is too difficult?