package p2p
import (
"bytes"
// "fmt"
"net"
"time"
"github.com/ethereum/go-ethereum/ethutil"
)
type Connection struct {
conn net.Conn
// conn NetworkConnection
timeout time.Duration
in chan []byte
out chan []byte
err chan *PeerError
closingIn chan chan bool
closingOut chan chan bool
}
// const readBufferLength = 2 //for testing
const readBufferLength = 1440
const partialsQueueSize = 10
const maxPendingQueueSize = 1
const defaultTimeout = 500
var magicToken = []byte{34, 64, 8, 145}
func (self *Connection) Open() {
go self.startRead()
go self.startWrite()
}
func (self *Connection) Close() {
self.closeIn()
self.closeOut()
}
func (self *Connection) closeIn() {
errc := make(chan bool)
self.closingIn <- errc
<-errc
}
func (self *Connection) closeOut() {
errc := make(chan bool)
self.closingOut <- errc
<-errc
}
func NewConnection(conn net.Conn, errchan chan *PeerError) *Connection {
return &Connection{
conn: conn,
timeout: defaultTimeout,
in: make(chan []byte),
out: make(chan []byte),
err: errchan,
closingIn: make(chan chan bool, 1),
closingOut: make(chan chan bool, 1),
}
}
func (self *Connection) Read() <-chan []byte {
return self.in
}
func (self *Connection) Write() chan<- []byte {
return self.out
}
func (self *Connection) Error() <-chan *PeerError {
return self.err
}
func (self *Connection) startRead() {
payloads := make(chan []byte)
done := make(chan *PeerError)
pending := [][]byte{}
var head []byte
var wait time.Duration // initally 0 (no delay)
read := time.After(wait * time.Millisecond)
for {
// if pending empty, nil channel blocks
var in chan []byte
if len(pending) > 0 {
in = self.in // enable send case
head = pending[0]
} else {
in = nil
}
select {
case <-read:
go self.read(payloads, done)
case err := <-done:
if err == nil { // no error but nothing to read
if len(pending) < maxPendingQueueSize {
wait = 100
} else if wait == 0 {
wait = 100
} else {
wait = 2 * wait
}
} else {
self.err <- err // report error
wait = 100
}
read = time.After(wait * time.Millisecond)
case payload := <-payloads:
pending = append(pending, payload)
if len(pending) < maxPendingQueueSize {
wait = 0
} else {
wait = 100
}
read = time.After(wait * time.Millisecond)
case in <- head:
pending = pending[1:]
case errc := <-self.closingIn:
errc <- true
close(self.in)
return
}
}
}
func (self *Connection) startWrite() {
pending := [][]byte{}
done := make(chan *PeerError)
writing := false
for {
if len(pending) > 0 && !writing {
writing = true
go self.write(pending[0], done)
}
select {
case payload := <-self.out:
pending = append(pending, payload)
case err := <-done:
if err == nil {
pending = pending[1:]
writing = false
} else {
self.err <- err // report error
}
case errc := <-self.closingOut:
errc <- true
close(self.out)
return
}
}
}
func pack(payload []byte) (packet []byte) {
length := ethutil.NumberToBytes(uint32(len(payload)), 32)
// return error if too long?
// Write magic token and payload length (first 8 bytes)
packet = append(magicToken, length...)
packet = append(packet, payload...)
return
}
func avoidPanic(done chan *PeerError) {
if rec := recover(); rec != nil {
err := NewPeerError(MiscError, " %v", rec)
logger.Debugln(err)
done <- err
}
}
func (self *Connection) write(payload []byte, done chan *PeerError) {
defer avoidPanic(done)
var err *PeerError
_, ok := self.conn.Write(pack(payload))
if ok != nil {
err = NewPeerError(WriteError, " %v", ok)
logger.Debugln(err)
}
done <- err
}
func (self *Connection) read(payloads chan []byte, done chan *PeerError) {
//defer avoidPanic(done)
partials := make(chan []byte, partialsQueueSize)
errc := make(chan *PeerError)
go self.readPartials(partials, errc)
packet := []byte{}
length := 8
start := true
var err *PeerError
out:
for {
// appends partials read via connection until packet is
// - either parseable (>=8bytes)
// - or complete (payload fully consumed)
for len(packet) < length {
partial, ok := <-partials
if !ok { // partials channel is closed
err = <-errc
if err == nil && len(packet) > 0 {
if start {
err = NewPeerError(PacketTooShort, "%v", packet)
} else {
err = NewPeerError(PayloadTooShort, "%d < %d", len(packet), length)
}
}
break out
}
packet = append(packet, partial...)
}
if start {
// at least 8 bytes read, can validate packet
if bytes.Compare(magicToken, packet[:4]) != 0 {
err = NewPeerError(MagicTokenMismatch, " received %v", packet[:4])
break
}
length = int(ethutil.BytesToNumber(packet[4:8]))
packet = packet[8:]
if length > 0 {
start = false // now consuming payload
} else { //penalize peer but read on
self.err <- NewPeerError(EmptyPayload, "")
length = 8
}
} else {
// packet complete (payload fully consumed)
payloads <- packet[:length]
packet = packet[length:] // resclice packet
start = true
length = 8
}
}
// this stops partials read via the connection, should we?
//if err != nil {
// select {
// case errc <- err
// default:
//}
done <- err
}
func (self *Connection) readPartials(partials chan []byte, errc chan *PeerError) {
defer close(partials)
for {
// Give buffering some time
self.conn.SetReadDeadline(time.Now().Add(self.timeout * time.Millisecond))
buffer := make([]byte, readBufferLength)
// read partial from connection
bytesRead, err := self.conn.Read(buffer)
if err == nil || err.Error() == "EOF" {
if bytesRead > 0 {
partials <- buffer[:bytesRead]
}
if err != nil && err.Error() == "EOF" {
break
}
} else {
// unexpected error, report to errc
err := NewPeerError(ReadError, " %v", err)
logger.Debugln(err)
errc <- err
return // will close partials channel
}
}
close(errc)
}
