Kademlia connect to peer by dns address

[bokoto000]

We have a predefined list of nodes that we must connect to. We’re bootstrapping using Kademlia. However, we encounter an error when passing the address of the node.

Exception in thread "main" java.util.concurrent.CompletionException: org.xbill.DNS.lookup.NoSuchDomainException
	at java.base/java.util.concurrent.CompletableFuture.encodeRelay(CompletableFuture.java:368)
	at java.base/java.util.concurrent.CompletableFuture.completeRelay(CompletableFuture.java:377)
	at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1152)
	at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
	at java.base/java.util.concurrent.CompletableFuture.postFire(CompletableFuture.java:614)
	at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1163)
	at java.base/java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:483)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:387)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1311)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1840)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1806)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:177)
Caused by: org.xbill.DNS.lookup.NoSuchDomainException
	at org.xbill.DNS.lookup.LookupSession.buildResult(LookupSession.java:593)
	at org.xbill.DNS.lookup.LookupSession.lambda$lookupWithResolver$7(LookupSession.java:479)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:646)
	... 9 more

The following code is able to reproduce the problem:

var dadr = DnsAddr.resolve("/dnsaddr/0.westend.paritytech.net/tcp/30333/p2p/12D3KooWKer94o1REDPtAhjtYR4SdLehnSrN8PEhBnZm5NBoCrMC");

DnsAddr is imported from org.peergos.protocol.dnsaddr.DnsAddr.

The peer we are trying to connect is:

/dns/0.westend.paritytech.net/tcp/30333/p2p/12D3KooWKer94o1REDPtAhjtYR4SdLehnSrN8PEhBnZm5NBoCrMC

We tried changing the format of the address but it didn’t work out:

/dnsaddr/0.westend.paritytech.net/p2p/12D3KooWKer94o1REDPtAhjtYR4SdLehnSrN8PEhBnZm5NBoCrMC

[ianopolous]

You have not setup your DNS correctly.

dig +short _dnsaddr.0.westend.paritytech.net txt

See details here: https://github.com/libp2p/specs/blob/master/addressing/README.md#dnsaddr-links

But I think you don't want dnsaddr, but rather dns, dns4 or dns6

[bokoto000]

I believe my DNS is set correctly.
The following code returns correctly an ipv4 address:

adr = InetAddress.getByName("0.westend.paritytech.net");
System.out.println(adr.getHostAddress());

I'm trying to populate Kademlia with peers using the findClosestPeers method of the Kademlia class. I get the following error for every address that has /dns/ in the beginning.

java.lang.IllegalArgumentException: Malformed multiaddr: '/dns/boot.stake.plus/tcp/37332
	at io.libp2p.core.multiformats.Multiaddr$Companion.parseString(Multiaddr.kt:195)

Populating Kademlia with peers using the bootstrapRoutingTable method of the Kademlia class also returns an error:

java.lang.IllegalArgumentException: Malformed multiaddr: '/dns/0.westend.paritytech.net/tcp/30333/ipfs/12D3KooWKer94o1REDPtAhjtYR4SdLehnSrN8PEhBnZm5NBoCrMC'
Caused by: java.lang.IllegalArgumentException: Unknown protocol name: 'dns'

Using dnsaddr or ip4 however works.

[ianopolous]

dnsaddr does not mean the domain points to an ip address. It is an ipfs specific txt record. See the link above.

[bokoto000]

I see. However, I am not sure that this helps me with the issue.
When I bootstrap Kademlia with boot node:/dns/0.westend.paritytech.net/tcp/30333/p2p/12D3KooWKer94o1REDPtAhjtYR4SdLehnSrN8PEhBnZm5NBoCrMC I recieve this exception:

Malformed multiaddr: '/dns/0.westend.paritytech.net/tcp/30333/ipfs/12D3KooWKer94o1REDPtAhjtYR4SdLehnSrN8PEhBnZm5NBoCrMC

Can I use /dns/ addresses for boot nodes and dial them?

[ianopolous]

That's an upstream bug in jvm-libp2p. You can work around it using dns4.