github.com/cerc-io/go-ethereum@v1.9.7/cmd/devp2p/crawl.go (about)

     1  // Copyright 2019 The go-ethereum Authors
     2  // This file is part of go-ethereum.
     3  //
     4  // go-ethereum is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // go-ethereum is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU General Public License
    15  // along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package main
    18  
    19  import (
    20  	"time"
    21  
    22  	"github.com/ethereum/go-ethereum/log"
    23  	"github.com/ethereum/go-ethereum/p2p/discover"
    24  	"github.com/ethereum/go-ethereum/p2p/enode"
    25  )
    26  
    27  type crawler struct {
    28  	input     nodeSet
    29  	output    nodeSet
    30  	disc      *discover.UDPv4
    31  	iters     []enode.Iterator
    32  	inputIter enode.Iterator
    33  	ch        chan *enode.Node
    34  	closed    chan struct{}
    35  
    36  	// settings
    37  	revalidateInterval time.Duration
    38  }
    39  
    40  func newCrawler(input nodeSet, disc *discover.UDPv4, iters ...enode.Iterator) *crawler {
    41  	c := &crawler{
    42  		input:     input,
    43  		output:    make(nodeSet, len(input)),
    44  		disc:      disc,
    45  		iters:     iters,
    46  		inputIter: enode.IterNodes(input.nodes()),
    47  		ch:        make(chan *enode.Node),
    48  		closed:    make(chan struct{}),
    49  	}
    50  	c.iters = append(c.iters, c.inputIter)
    51  	// Copy input to output initially. Any nodes that fail validation
    52  	// will be dropped from output during the run.
    53  	for id, n := range input {
    54  		c.output[id] = n
    55  	}
    56  	return c
    57  }
    58  
    59  func (c *crawler) run(timeout time.Duration) nodeSet {
    60  	var (
    61  		timeoutTimer = time.NewTimer(timeout)
    62  		timeoutCh    <-chan time.Time
    63  		doneCh       = make(chan enode.Iterator, len(c.iters))
    64  		liveIters    = len(c.iters)
    65  	)
    66  	for _, it := range c.iters {
    67  		go c.runIterator(doneCh, it)
    68  	}
    69  
    70  loop:
    71  	for {
    72  		select {
    73  		case n := <-c.ch:
    74  			c.updateNode(n)
    75  		case it := <-doneCh:
    76  			if it == c.inputIter {
    77  				// Enable timeout when we're done revalidating the input nodes.
    78  				log.Info("Revalidation of input set is done", "len", len(c.input))
    79  				if timeout > 0 {
    80  					timeoutCh = timeoutTimer.C
    81  				}
    82  			}
    83  			if liveIters--; liveIters == 0 {
    84  				break loop
    85  			}
    86  		case <-timeoutCh:
    87  			break loop
    88  		}
    89  	}
    90  
    91  	close(c.closed)
    92  	for _, it := range c.iters {
    93  		it.Close()
    94  	}
    95  	for ; liveIters > 0; liveIters-- {
    96  		<-doneCh
    97  	}
    98  	return c.output
    99  }
   100  
   101  func (c *crawler) runIterator(done chan<- enode.Iterator, it enode.Iterator) {
   102  	defer func() { done <- it }()
   103  	for it.Next() {
   104  		select {
   105  		case c.ch <- it.Node():
   106  		case <-c.closed:
   107  			return
   108  		}
   109  	}
   110  }
   111  
   112  func (c *crawler) updateNode(n *enode.Node) {
   113  	node, ok := c.output[n.ID()]
   114  
   115  	// Skip validation of recently-seen nodes.
   116  	if ok && time.Since(node.LastCheck) < c.revalidateInterval {
   117  		return
   118  	}
   119  
   120  	// Request the node record.
   121  	nn, err := c.disc.RequestENR(n)
   122  	node.LastCheck = truncNow()
   123  	if err != nil {
   124  		if node.Score == 0 {
   125  			// Node doesn't implement EIP-868.
   126  			log.Debug("Skipping node", "id", n.ID())
   127  			return
   128  		}
   129  		node.Score /= 2
   130  	} else {
   131  		node.N = nn
   132  		node.Seq = nn.Seq()
   133  		node.Score++
   134  		if node.FirstResponse.IsZero() {
   135  			node.FirstResponse = node.LastCheck
   136  		}
   137  		node.LastResponse = node.LastCheck
   138  	}
   139  
   140  	// Store/update node in output set.
   141  	if node.Score <= 0 {
   142  		log.Info("Removing node", "id", n.ID())
   143  		delete(c.output, n.ID())
   144  	} else {
   145  		log.Info("Updating node", "id", n.ID(), "seq", n.Seq(), "score", node.Score)
   146  		c.output[n.ID()] = node
   147  	}
   148  }
   149  
   150  func truncNow() time.Time {
   151  	return time.Now().UTC().Truncate(1 * time.Second)
   152  }