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p2p/discover: move bond logic from table to transport (#17048)

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* p2p/discover: move bond logic from table to transport

This commit moves node endpoint verification (bonding) from the table to
the UDP transport implementation. Previously, adding a node to the table
entailed pinging the node if needed. With this change, the ping-back
logic is embedded in the packet handler at a lower level.

It is easy to verify that the basic protocol is unchanged: we still
require a valid pong reply from the node before findnode is accepted.

The node database tracked the time of last ping sent to the node and
time of last valid pong received from the node. Node endpoints are
considered verified when a valid pong is received and the time of last
pong was called 'bond time'. The time of last ping sent was unused. In
this commit, the last ping database entry is repurposed to mean last
ping _received_. This entry is now used to track whether the node needs
to be pinged back.

The other big change is how nodes are added to the table. We used to add
nodes in Table.bond, which ran when a remote node pinged us or when we
encountered the node in a neighbors reply. The transport now adds to the
table directly after the endpoint is verified through ping. To ensure
that the Table can't be filled just by pinging the node repeatedly, we
retain the isInitDone check. During init, only nodes from neighbors
replies are added.

* p2p/discover: reduce findnode failure counter on success

* p2p/discover: remove unused parameter of loadSeedNodes

* p2p/discover: improve ping-back check and comments

* p2p/discover: add neighbors reply nodes always, not just during init
This commit is contained in:
Felix Lange
2018-07-03 15:24:12 +02:00
committed by Péter Szilágyi
parent 9da128db70
commit c73b654fd1
6 changed files with 147 additions and 245 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
p2p/discover/udp_test.go
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@ -124,7 +124,7 @@ func TestUDP_packetErrors(t *testing.T) {
test := newUDPTest(t)
defer test.table.Close()
test.packetIn(errExpired, pingPacket, &ping{From: testRemote, To: testLocalAnnounced, Version: Version})
test.packetIn(errExpired, pingPacket, &ping{From: testRemote, To: testLocalAnnounced, Version: 4})
test.packetIn(errUnsolicitedReply, pongPacket, &pong{ReplyTok: []byte{}, Expiration: futureExp})
test.packetIn(errUnknownNode, findnodePacket, &findnode{Expiration: futureExp})
test.packetIn(errUnsolicitedReply, neighborsPacket, &neighbors{Expiration: futureExp})
@ -247,7 +247,7 @@ func TestUDP_findnode(t *testing.T) {
// ensure there's a bond with the test node,
// findnode won't be accepted otherwise.
test.table.db.updateBondTime(PubkeyID(&test.remotekey.PublicKey), time.Now())
test.table.db.updateLastPongReceived(PubkeyID(&test.remotekey.PublicKey), time.Now())
// check that closest neighbors are returned.
test.packetIn(nil, findnodePacket, &findnode{Target: testTarget, Expiration: futureExp})
@ -273,10 +273,12 @@ func TestUDP_findnodeMultiReply(t *testing.T) {
test := newUDPTest(t)
defer test.table.Close()
rid := PubkeyID(&test.remotekey.PublicKey)
test.table.db.updateLastPingReceived(rid, time.Now())
// queue a pending findnode request
resultc, errc := make(chan []*Node), make(chan error)
go func() {
rid := PubkeyID(&test.remotekey.PublicKey)
ns, err := test.udp.findnode(rid, test.remoteaddr, testTarget)
if err != nil && len(ns) == 0 {
errc <- err
@ -328,7 +330,7 @@ func TestUDP_successfulPing(t *testing.T) {
defer test.table.Close()
// The remote side sends a ping packet to initiate the exchange.
go test.packetIn(nil, pingPacket, &ping{From: testRemote, To: testLocalAnnounced, Version: Version, Expiration: futureExp})
go test.packetIn(nil, pingPacket, &ping{From: testRemote, To: testLocalAnnounced, Version: 4, Expiration: futureExp})
// the ping is replied to.
test.waitPacketOut(func(p *pong) {