Fixing Bootstrapping

[Stebalien]

Version information:

v0.5.0-dev

Description:

Libp2p recently increased the minimum RSA key size to 2048 bits. While almost all nodes in the network are using 2048 bit keys already, most of the built-in bootstrap nodes are not.

Luckily, we did have some newer nodes using 2048 bit keys. Specifically, the /dnsaddr/bootstrap.libp2p.io nodes. Unfortunately:

1. These bootstrappers were added (relatively) recently. Nodes with older configs won't use them.
2. The DNS record for these bootstrappers was too large: 4 bootstrappers, 4 IP addresses per bootstrapper) to fit into a single UDP packet.

To solve 2, we switched to indirect dnsaddr records: now we have 4 top-level records that each resolve two two dnsaddr records, one for each IP address for each bootstrapper. These records all, individually, fit into single UDP packets.

Unfortunately, go-libp2p doesn't support recursive dnsaddr resolution: libp2p/go-libp2p#744.

---

So, we need to:

• Add support for recursive dnsaddr resolution to go-libp2p (Recursive dnsaddr resolution. libp2p/go-libp2p#744).
• Add a repo migration that:
  • Checks if we already have the new bootstrappers in the config. If so, skip.
  • Checks to see if we have bootstrappers with known sub 2048 bit keys. If not, skip.
  • Otherwise, remove them and replace these old bootstrappers with the new bootstrappers.
  • Replace the /ipfs part of these multiaddrs with /p2p (no reason not to).
• Test the migration.
• Update the repo version in go-ipfs.

[dirkmc]

@olizilla which of the peers have sub 2048 bit keys?

[olizilla]

The ones addressed by /dnsaddr... https://github.com/ipfs/go-ipfs-config/blob/98ec0ae9a3161d355da0615e54ca314232212615/bootstrap_peers.go#L22-L25

misread, the inverse of that... the ones not addressed by /dnsaddr are older and I believe all have 1024 bit keys, https://github.com/ipfs/go-ipfs-config/blob/98ec0ae9a3161d355da0615e54ca314232212615/bootstrap_peers.go#L26-L34

[Stebalien]

@olizilla & @dirkmc

Ok, so, the nodes with peer IDs that start with QmSoL are the ones we need to remove. Notably, mars (/ip4/104.131.131.82/tcp/4001/p2p/QmaCpDMGvV2BGHeYERUEnRQAwe3N8SzbUtfsmvsqQLuvuJ), uses a 4096 bit key. Let's leave that one where it is.

[Stebalien]

@olizilla so, something has come up: when we update our new bootstrappers to the next go-ipfs release, we need to use a custom build that can (a) connect to the old bootstrappers and (b) does not disconnect from the old bootstrappers. Otherwise, peers connecting to the old bootstrappers will be isolated from the rest of the network.

[olizilla]

Exciting! That's ok, we can roll out a custom build from a branch of go-ipfs like we do for gateways.

@Stebalien let me know the branch you set up for that, and I'll set up an autobuild rule for it on dockerhub.

[Stebalien]

👍