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fix(libp2p): filter out dnsaddrs for different peers #1954

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merged 2 commits into from
Aug 13, 2023

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achingbrain
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@achingbrain achingbrain commented Aug 10, 2023

Some multiaddrs like /dnsaddr/bootstrap.ipfs.io resolve to multiple PeerIds.

E.g:

% dig _dnsaddr.bootstrap.libp2p.io TXT

; <<>> DiG 9.10.6 <<>> _dnsaddr.bootstrap.libp2p.io TXT
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53473
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;_dnsaddr.bootstrap.libp2p.io.	IN	TXT

;; ANSWER SECTION:
_dnsaddr.bootstrap.libp2p.io. 261 IN	TXT	"dnsaddr=/dnsaddr/am6.bootstrap.libp2p.io/p2p/QmbLHAnMoJPWSCR5Zhtx6BHJX9KiKNN6tpvbUcqanj75Nb"
_dnsaddr.bootstrap.libp2p.io. 261 IN	TXT	"dnsaddr=/dnsaddr/ny5.bootstrap.libp2p.io/p2p/QmQCU2EcMqAqQPR2i9bChDtGNJchTbq5TbXJJ16u19uLTa"
_dnsaddr.bootstrap.libp2p.io. 261 IN	TXT	"dnsaddr=/dnsaddr/sg1.bootstrap.libp2p.io/p2p/QmcZf59bWwK5XFi76CZX8cbJ4BhTzzA3gU1ZjYZcYW3dwt"
_dnsaddr.bootstrap.libp2p.io. 261 IN	TXT	"dnsaddr=/dnsaddr/sv15.bootstrap.libp2p.io/p2p/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN"

This can cause problems when dialing those addresses with an explicit PeerId since resolving the dnsaddr returns addresses with embedded PeerIds that aren't for the node you are trying to dial so we need to filter those out.

The errors these cause are non-fatal but do consume resources dialing nodes we aren't going to be able to connect to.

Some multiaddrs like `/dnsaddr/bootstrap.ipfs.io` resolve to multiple
PeerIds.

E.g:

```console
% dig _dnsaddr.bootstrap.libp2p.io TXT

; <<>> DiG 9.10.6 <<>> _dnsaddr.bootstrap.libp2p.io TXT
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53473
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;_dnsaddr.bootstrap.libp2p.io.	IN	TXT

;; ANSWER SECTION:
_dnsaddr.bootstrap.libp2p.io. 261 IN	TXT	"dnsaddr=/dnsaddr/am6.bootstrap.libp2p.io/p2p/QmbLHAnMoJPWSCR5Zhtx6BHJX9KiKNN6tpvbUcqanj75Nb"
_dnsaddr.bootstrap.libp2p.io. 261 IN	TXT	"dnsaddr=/dnsaddr/ny5.bootstrap.libp2p.io/p2p/QmQCU2EcMqAqQPR2i9bChDtGNJchTbq5TbXJJ16u19uLTa"
_dnsaddr.bootstrap.libp2p.io. 261 IN	TXT	"dnsaddr=/dnsaddr/sg1.bootstrap.libp2p.io/p2p/QmcZf59bWwK5XFi76CZX8cbJ4BhTzzA3gU1ZjYZcYW3dwt"
_dnsaddr.bootstrap.libp2p.io. 261 IN	TXT	"dnsaddr=/dnsaddr/sv15.bootstrap.libp2p.io/p2p/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN"
```

This can cause problems when dialing those addresses with a PeerId
since resolving the dnsaddr returns addresses with embedded PeerIds
that aren't for the node you are trying to dial so filter those out.

The errors these cause are non-fatal but do consume resources dialing
nodes we aren't going to be able to connect to.
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nit

return peerId.equals(addrPeerId)
}

return true

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should the default be true? Can this be restructured such that it's only true when all conditions are met and defaults to false otherwise?

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I think it makes sense to fallback to true and filter out the false on the way

Comment on lines +321 to +324
const addrPeerId = addr.multiaddr.getPeerId()
if (peerId != null && addrPeerId != null) {
return peerId.equals(addrPeerId)
}

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one of the null checks look redundant. Also can the equality check be the other way? just for the sake of convention

Suggested change
const addrPeerId = addr.multiaddr.getPeerId()
if (peerId != null && addrPeerId != null) {
return peerId.equals(addrPeerId)
}
const addrPeerId = addr.multiaddr.getPeerId()
if (addrPeerId != null) {
return addrPeerId.equals(peerId)
}

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You have to null guard on peerId again, if that's what you mean, because the type is PeerId | undefined - execution of the code takes place in a callback so TSC can't guarantee it's not been set back to undefined before the callback is invoked.

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Lgtm, comment regarding recent convo with peerId missing from some multiaddrs (issue incoming after breakfast)

// - this can happen with addresses like bootstrap.libp2p.io that resolve
// to multiple different peers
const addrPeerId = addr.multiaddr.getPeerId()
if (peerId != null && addrPeerId != null) {
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If its p2p-circuit addrPeerId will likely be null always

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related: #1961

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lgtm!

@achingbrain achingbrain merged commit a31b420 into master Aug 13, 2023
@achingbrain achingbrain deleted the fix/filter-out-bad-dnsaddrs branch August 13, 2023 07:09
This was referenced Jan 18, 2024
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3 participants