File: pex_reactor.go

package info (click to toggle)
tendermint-go-p2p 0.0~git20170113.0.3d98f67-1
  • links: PTS, VCS
  • area: main
  • in suites: buster
  • size: 248 kB
  • ctags: 425
  • sloc: sh: 23; makefile: 4
file content (256 lines) | stat: -rw-r--r-- 6,195 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
package p2p

import (
	"bytes"
	"errors"
	"fmt"
	"math/rand"
	"reflect"
	"time"

	. "github.com/tendermint/go-common"
	"github.com/tendermint/go-wire"
)

var pexErrInvalidMessage = errors.New("Invalid PEX message")

const (
	PexChannel               = byte(0x00)
	ensurePeersPeriodSeconds = 30
	minNumOutboundPeers      = 10
	maxPexMessageSize        = 1048576 // 1MB
)

/*
PEXReactor handles PEX (peer exchange) and ensures that an
adequate number of peers are connected to the switch.
*/
type PEXReactor struct {
	BaseReactor

	sw   *Switch
	book *AddrBook
}

func NewPEXReactor(book *AddrBook) *PEXReactor {
	pexR := &PEXReactor{
		book: book,
	}
	pexR.BaseReactor = *NewBaseReactor(log, "PEXReactor", pexR)
	return pexR
}

func (pexR *PEXReactor) OnStart() error {
	pexR.BaseReactor.OnStart()
	go pexR.ensurePeersRoutine()
	return nil
}

func (pexR *PEXReactor) OnStop() {
	pexR.BaseReactor.OnStop()
}

// Implements Reactor
func (pexR *PEXReactor) GetChannels() []*ChannelDescriptor {
	return []*ChannelDescriptor{
		&ChannelDescriptor{
			ID:                PexChannel,
			Priority:          1,
			SendQueueCapacity: 10,
		},
	}
}

// Implements Reactor
func (pexR *PEXReactor) AddPeer(peer *Peer) {
	// Add the peer to the address book
	netAddr := NewNetAddressString(peer.ListenAddr)
	if peer.IsOutbound() {
		if pexR.book.NeedMoreAddrs() {
			pexR.RequestPEX(peer)
		}
	} else {
		// For inbound connections, the peer is its own source
		// (For outbound peers, the address is already in the books)
		pexR.book.AddAddress(netAddr, netAddr)
	}
}

// Implements Reactor
func (pexR *PEXReactor) RemovePeer(peer *Peer, reason interface{}) {
	// TODO
}

// Implements Reactor
// Handles incoming PEX messages.
func (pexR *PEXReactor) Receive(chID byte, src *Peer, msgBytes []byte) {

	// decode message
	_, msg, err := DecodeMessage(msgBytes)
	if err != nil {
		log.Warn("Error decoding message", "error", err)
		return
	}
	log.Notice("Received message", "msg", msg)

	switch msg := msg.(type) {
	case *pexRequestMessage:
		// src requested some peers.
		// TODO: prevent abuse.
		pexR.SendAddrs(src, pexR.book.GetSelection())
	case *pexAddrsMessage:
		// We received some peer addresses from src.
		// TODO: prevent abuse.
		// (We don't want to get spammed with bad peers)
		srcAddr := src.Connection().RemoteAddress
		for _, addr := range msg.Addrs {
			pexR.book.AddAddress(addr, srcAddr)
		}
	default:
		log.Warn(Fmt("Unknown message type %v", reflect.TypeOf(msg)))
	}

}

// Asks peer for more addresses.
func (pexR *PEXReactor) RequestPEX(peer *Peer) {
	peer.Send(PexChannel, struct{ PexMessage }{&pexRequestMessage{}})
}

func (pexR *PEXReactor) SendAddrs(peer *Peer, addrs []*NetAddress) {
	peer.Send(PexChannel, struct{ PexMessage }{&pexAddrsMessage{Addrs: addrs}})
}

// Ensures that sufficient peers are connected. (continuous)
func (pexR *PEXReactor) ensurePeersRoutine() {
	// Randomize when routine starts
	time.Sleep(time.Duration(rand.Int63n(500*ensurePeersPeriodSeconds)) * time.Millisecond)

	// fire once immediately.
	pexR.ensurePeers()
	// fire periodically
	timer := NewRepeatTimer("pex", ensurePeersPeriodSeconds*time.Second)
FOR_LOOP:
	for {
		select {
		case <-timer.Ch:
			pexR.ensurePeers()
		case <-pexR.Quit:
			break FOR_LOOP
		}
	}

	// Cleanup
	timer.Stop()
}

// Ensures that sufficient peers are connected. (once)
func (pexR *PEXReactor) ensurePeers() {
	numOutPeers, _, numDialing := pexR.Switch.NumPeers()
	numToDial := minNumOutboundPeers - (numOutPeers + numDialing)
	log.Info("Ensure peers", "numOutPeers", numOutPeers, "numDialing", numDialing, "numToDial", numToDial)
	if numToDial <= 0 {
		return
	}
	toDial := NewCMap()

	// Try to pick numToDial addresses to dial.
	// TODO: improve logic.
	for i := 0; i < numToDial; i++ {
		newBias := MinInt(numOutPeers, 8)*10 + 10
		var picked *NetAddress
		// Try to fetch a new peer 3 times.
		// This caps the maximum number of tries to 3 * numToDial.
		for j := 0; j < 3; j++ {
			try := pexR.book.PickAddress(newBias)
			if try == nil {
				break
			}
			alreadySelected := toDial.Has(try.IP.String())
			alreadyDialing := pexR.Switch.IsDialing(try)
			alreadyConnected := pexR.Switch.Peers().Has(try.IP.String())
			if alreadySelected || alreadyDialing || alreadyConnected {
				/*
					log.Info("Cannot dial address", "addr", try,
						"alreadySelected", alreadySelected,
						"alreadyDialing", alreadyDialing,
						"alreadyConnected", alreadyConnected)
				*/
				continue
			} else {
				log.Info("Will dial address", "addr", try)
				picked = try
				break
			}
		}
		if picked == nil {
			continue
		}
		toDial.Set(picked.IP.String(), picked)
	}

	// Dial picked addresses
	for _, item := range toDial.Values() {
		go func(picked *NetAddress) {
			_, err := pexR.Switch.DialPeerWithAddress(picked)
			if err != nil {
				pexR.book.MarkAttempt(picked)
			}
		}(item.(*NetAddress))
	}

	// If we need more addresses, pick a random peer and ask for more.
	if pexR.book.NeedMoreAddrs() {
		if peers := pexR.Switch.Peers().List(); len(peers) > 0 {
			i := rand.Int() % len(peers)
			peer := peers[i]
			log.Info("No addresses to dial. Sending pexRequest to random peer", "peer", peer)
			pexR.RequestPEX(peer)
		}
	}
}

//-----------------------------------------------------------------------------
// Messages

const (
	msgTypeRequest = byte(0x01)
	msgTypeAddrs   = byte(0x02)
)

type PexMessage interface{}

var _ = wire.RegisterInterface(
	struct{ PexMessage }{},
	wire.ConcreteType{&pexRequestMessage{}, msgTypeRequest},
	wire.ConcreteType{&pexAddrsMessage{}, msgTypeAddrs},
)

func DecodeMessage(bz []byte) (msgType byte, msg PexMessage, err error) {
	msgType = bz[0]
	n := new(int)
	r := bytes.NewReader(bz)
	msg = wire.ReadBinary(struct{ PexMessage }{}, r, maxPexMessageSize, n, &err).(struct{ PexMessage }).PexMessage
	return
}

/*
A pexRequestMessage requests additional peer addresses.
*/
type pexRequestMessage struct {
}

func (m *pexRequestMessage) String() string {
	return "[pexRequest]"
}

/*
A message with announced peer addresses.
*/
type pexAddrsMessage struct {
	Addrs []*NetAddress
}

func (m *pexAddrsMessage) String() string {
	return fmt.Sprintf("[pexAddrs %v]", m.Addrs)
}