IPv6 Support for discv5

[kdeme]

IPv6 and multiple (ipv4 + ipv6) listening addresses support placeholder.

[jlokier]

Just to confirm, discv4 could also benefit from IPv6 support. We do seesome real IPv6 addresses from IPv4 discovery.

We also see many IPv4 nodes represented by mapped IPv4-in-IPv6 address (ffff::a.b.c.d). (These just need those addresses converting when parsing the incoming messages.) Currently the effect of these is to cause unsightly error messages due to IPv6 not being supported.

[yorickdowne]

This feels quite stale, yet it is still relevant. @tersec can I ping you here. Let me know if you want a fresh issue.

Desired feature: Auto-ENR for IPv6, so users behind CGNAT (home stakers) can be discoverable. This currently works in Lighthouse and Grandine. Nimbus could be client numbah 3! 😁 .

Nimbus has dual-stack on by default, but that doesn't extend to becoming discoverable. See discovery_addresses below. The shown IPv4 public has been changed by me.

{"data":{"peer_id":"redacted","enr":"enr:-redacted":["/ip6/::1/tcp/9000/p2p/redacted","/ip6/fde8:f1f6:da71:1::2/tcp/9000/p2p/redacted","/ip6/fe80::24d1:39ff:fe6d:46c0/tcp/9000/p2p/redacted","/ip4/127.0.0.1/tcp/9000/p2p/redacted","/ip4/172.21.0.2/tcp/9000/p2p/redacted"],"discovery_addresses":["/ip4/12.3.7.1/udp/9000/p2p/redacted"],"metadata":{"seq_number":"2","syncnets":"0x00","attnets":"0x0000000000000018","custody_group_count":"4"}}}

[tersec]

This feels quite stale, yet it is still relevant. @tersec can I ping you here. Let me know if you want a fresh issue.

Desired feature: Auto-ENR for IPv6, so users behind CGNAT (home stakers) can be discoverable. This currently works in Lighthouse, and I am testing other clients.

Nimbus has dual-stack on by default, but that doesn't extend to becoming discoverable. See discovery_addresses below. The shown IPv4 public has been changed by me.

{"data":{"peer_id":"redacted","enr":"enr:-redacted":["/ip6/::1/tcp/9000/p2p/redacted","/ip6/fde8:f1f6:da71:1::2/tcp/9000/p2p/redacted","/ip6/fe80::24d1:39ff:fe6d:46c0/tcp/9000/p2p/redacted","/ip4/127.0.0.1/tcp/9000/p2p/redacted","/ip4/172.21.0.2/tcp/9000/p2p/redacted"],"discovery_addresses":["/ip4/12.3.7.1/udp/9000/p2p/redacted"],"metadata":{"seq_number":"2","syncnets":"0x00","attnets":"0x0000000000000018","custody_group_count":"4"}}}

• IPv6 support for discv5 and ENR #837

[yorickdowne]

Hugely appreciate that you are looking at this!