plugeth/cmd/devp2p/crawl.go

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// Copyright 2019 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
package main
import (
"time"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/p2p/discover"
"github.com/ethereum/go-ethereum/p2p/enode"
)
type crawler struct {
input nodeSet
output nodeSet
disc *discover.UDPv4
iters []enode.Iterator
inputIter enode.Iterator
ch chan *enode.Node
closed chan struct{}
// settings
revalidateInterval time.Duration
}
func newCrawler(input nodeSet, disc *discover.UDPv4, iters ...enode.Iterator) *crawler {
c := &crawler{
input: input,
output: make(nodeSet, len(input)),
disc: disc,
iters: iters,
inputIter: enode.IterNodes(input.nodes()),
ch: make(chan *enode.Node),
closed: make(chan struct{}),
}
c.iters = append(c.iters, c.inputIter)
// Copy input to output initially. Any nodes that fail validation
// will be dropped from output during the run.
for id, n := range input {
c.output[id] = n
}
return c
}
func (c *crawler) run(timeout time.Duration) nodeSet {
var (
timeoutTimer = time.NewTimer(timeout)
timeoutCh <-chan time.Time
doneCh = make(chan enode.Iterator, len(c.iters))
liveIters = len(c.iters)
)
defer timeoutTimer.Stop()
for _, it := range c.iters {
go c.runIterator(doneCh, it)
}
loop:
for {
select {
case n := <-c.ch:
c.updateNode(n)
case it := <-doneCh:
if it == c.inputIter {
// Enable timeout when we're done revalidating the input nodes.
log.Info("Revalidation of input set is done", "len", len(c.input))
if timeout > 0 {
timeoutCh = timeoutTimer.C
}
}
if liveIters--; liveIters == 0 {
break loop
}
case <-timeoutCh:
break loop
}
}
close(c.closed)
for _, it := range c.iters {
it.Close()
}
for ; liveIters > 0; liveIters-- {
<-doneCh
}
return c.output
}
func (c *crawler) runIterator(done chan<- enode.Iterator, it enode.Iterator) {
defer func() { done <- it }()
for it.Next() {
select {
case c.ch <- it.Node():
case <-c.closed:
return
}
}
}
func (c *crawler) updateNode(n *enode.Node) {
node, ok := c.output[n.ID()]
// Skip validation of recently-seen nodes.
if ok && time.Since(node.LastCheck) < c.revalidateInterval {
return
}
// Request the node record.
nn, err := c.disc.RequestENR(n)
node.LastCheck = truncNow()
if err != nil {
if node.Score == 0 {
// Node doesn't implement EIP-868.
log.Debug("Skipping node", "id", n.ID())
return
}
node.Score /= 2
} else {
node.N = nn
node.Seq = nn.Seq()
node.Score++
if node.FirstResponse.IsZero() {
node.FirstResponse = node.LastCheck
}
node.LastResponse = node.LastCheck
}
// Store/update node in output set.
if node.Score <= 0 {
log.Info("Removing node", "id", n.ID())
delete(c.output, n.ID())
} else {
log.Info("Updating node", "id", n.ID(), "seq", n.Seq(), "score", node.Score)
c.output[n.ID()] = node
}
}
func truncNow() time.Time {
return time.Now().UTC().Truncate(1 * time.Second)
}