Attempt to lookup an empty peer ID

[Stebalien]

=== FAIL: core/coreapi/test TestIface/Name/TestBasicPublishResolveKey (14.84s)
panic: runtime error: index out of range [-1]

goroutine 82879 [running]:
github.com/libp2p/go-libp2p-peerstore/pstoremem.(*addrSegments).get(...)
	pkg/mod/github.com/libp2p/go-libp2p-peerstore@v0.2.2/pstoremem/addr_book.go:50
github.com/libp2p/go-libp2p-peerstore/pstoremem.(*memoryAddrBook).Addrs(0xc0036da000, 0x0, 0x0, 0x0, 0x0, 0x0)
	pkg/mod/github.com/libp2p/go-libp2p-peerstore@v0.2.2/pstoremem/addr_book.go:313 +0x168
github.com/libp2p/go-libp2p-peerstore/pstoremem.(*pstoremem).PeerInfo(0xc0036ed560, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
	pkg/mod/github.com/libp2p/go-libp2p-peerstore@v0.2.2/pstoremem/peerstore.go:71 +0x66
github.com/libp2p/go-libp2p-peerstore.PeerInfos(0x1bf85e0, 0xc0036ed560, 0xc005825a40, 0x4, 0x4, 0xc005825a40, 0x3, 0x4)
	pkg/mod/github.com/libp2p/go-libp2p-peerstore@v0.2.2/peerstore.go:82 +0xbc
github.com/libp2p/go-libp2p-kad-dht.(*IpfsDHT).handleFindPeer(0xc0036af500, 0x1bde300, 0xc0061e76e0, 0xc000e6ec30, 0x22, 0xc005880d00, 0x1690ba0, 0x175e201, 0xc0065ba0b0)
	pkg/mod/github.com/libp2p/go-libp2p-kad-dht@v0.6.1/handlers.go:289 +0x1f6
github.com/libp2p/go-libp2p-kad-dht.(*IpfsDHT).handleNewMessage(0xc0036af500, 0x1bf14e0, 0xc004eedaa0, 0xa22c00)
	pkg/mod/github.com/libp2p/go-libp2p-kad-dht@v0.6.1/dht_net.go:151 +0x82a
github.com/libp2p/go-libp2p-kad-dht.(*IpfsDHT).handleNewStream(0xc0036af500, 0x1bf14e0, 0xc004eedaa0)
	pkg/mod/github.com/libp2p/go-libp2p-kad-dht@v0.6.1/dht_net.go:66 +0x83
github.com/libp2p/go-libp2p/p2p/host/basic.(*BasicHost).SetStreamHandler.func1(0xc001139200, 0xf, 0x7effdc6b9030, 0xc004eedaa0, 0x1, 0x0)
	pkg/mod/github.com/libp2p/go-libp2p@v0.7.4/p2p/host/basic/basic_host.go:417 +0x9d
created by github.com/libp2p/go-libp2p/p2p/host/basic.(*BasicHost).newStreamHandler
	pkg/mod/github.com/libp2p/go-libp2p@v0.7.4/p2p/host/basic/basic_host.go:301 +0x636

FAIL	github.com/ipfs/go-ipfs/core/coreapi/test	14.840s

This error happens when we try to lookup an empty ("") peer ID. See: libp2p/go-libp2p-peerstore#88

https://app.circleci.com/pipelines/github/ipfs/go-ipfs/2340/workflows/be5e6996-eb05-49c2-9b1b-7e26c3719c06/jobs/28662

[Stebalien]

We should probably just validate that all messages actually have a key in the main handelNewMessage functoin. I'm also not sure why this is showing up in tests now. Are we forgetting to set the key in one of our requests?

[aschmahmann]

@Stebalien my guess is that the change that exposed this error was that we now search the peerstore for targetPid and return it, where as previously we only returned targetPid if we were Connected to it.

go-libp2p-kad-dht/handlers.go

Lines 278 to 289 in 4a4e60e

	if !found {
	closest = append(closest, targetPid)
	}
	}
	}
	if closest == nil {
	return resp, nil
	}
	// TODO: pstore.PeerInfos should move to core (=> peerstore.AddrInfos).
	closestinfos := pstore.PeerInfos(dht.peerstore, closest)

.

We should investigate why this is happening at all though.

Edit: After some spelunking I think the reason that there's a peer.ID of "" being propagated around is because https://github.com/ipfs/go-ipfs-provider/blob/3a98ef95f2e412a39a7b591cc2ce3ed5affb18c3/simple/provider.go#L88-L89 does not check if the provider dequeing channel is closed before calling doProvide(c cid.Cid) this causes an empty cid to be provided when the test ends, which causes an empty key to be looked for in GetClosestPeers which because of our weirdness in #556 looks like we're actually searching for an empty peerID.