path: root/peer.go

package main

import (
    "github.com/ethereum/ethutil-go"
    "github.com/ethereum/ethwire-go"
    "log"
    "net"
    "strconv"
    "sync/atomic"
    "time"
)

const (
    // The size of the output buffer for writing messages
    outputBufferSize = 50
)

type Peer struct {
    // Server interface
    server *Server
    // Net connection
    conn net.Conn
    // Output queue which is used to communicate and handle messages
    outputQueue chan *ethwire.Msg
    // Quit channel
    quit chan bool
    // Determines whether it's an inbound or outbound peer
    inbound bool
    // Flag for checking the peer's connectivity state
    connected  int32
    disconnect int32
    // Last known message send
    lastSend time.Time
    // Indicated whether a verack has been send or not
    // This flag is used by writeMessage to check if messages are allowed
    // to be send or not. If no version is known all messages are ignored.
    versionKnown bool

    // Last received pong message
    lastPong int64
    // Indicates whether a MsgGetPeersTy was requested of the peer
    // this to prevent receiving false peers.
    requestedPeerList bool
}

func NewPeer(conn net.Conn, server *Server, inbound bool) *Peer {
    return &Peer{
        outputQueue: make(chan *ethwire.Msg, outputBufferSize),
        quit:        make(chan bool),
        server:      server,
        conn:        conn,
        inbound:     inbound,
        disconnect:  0,
        connected:   1,
    }
}

func NewOutboundPeer(addr string, server *Server) *Peer {
    p := &Peer{
        outputQueue: make(chan *ethwire.Msg, outputBufferSize),
        quit:        make(chan bool),
        server:      server,
        inbound:     false,
        connected:   0,
        disconnect:  0,
    }

    // Set up the connection in another goroutine so we don't block the main thread
    go func() {
        conn, err := net.Dial("tcp", addr)
        if err != nil {
            p.Stop()
        }
        p.conn = conn

        // Atomically set the connection state
        atomic.StoreInt32(&p.connected, 1)
        atomic.StoreInt32(&p.disconnect, 0)

        log.Println("Connected to peer ::", conn.RemoteAddr())

        p.Start()
    }()

    return p
}

// Outputs any RLP encoded data to the peer
func (p *Peer) QueueMessage(msg *ethwire.Msg) {
    p.outputQueue <- msg
}

func (p *Peer) writeMessage(msg *ethwire.Msg) {
    // Ignore the write if we're not connected
    if atomic.LoadInt32(&p.connected) != 1 {
        return
    }

    if !p.versionKnown {
        switch msg.Type {
        case ethwire.MsgHandshakeTy: // Ok
        default: // Anything but ack is allowed
            return
        }
    }

    err := ethwire.WriteMessage(p.conn, msg)
    if err != nil {
        log.Println("Can't send message:", err)
        // Stop the client if there was an error writing to it
        p.Stop()
        return
    }
}

// Outbound message handler. Outbound messages are handled here
func (p *Peer) HandleOutbound() {
    // The ping timer. Makes sure that every 2 minutes a ping is send to the peer
    tickleTimer := time.NewTicker(2 * time.Minute)
out:
    for {
        select {
        // Main message queue. All outbound messages are processed through here
        case msg := <-p.outputQueue:
            p.writeMessage(msg)

            p.lastSend = time.Now()

        case <-tickleTimer.C:
            p.writeMessage(&ethwire.Msg{Type: ethwire.MsgPingTy})

        // Break out of the for loop if a quit message is posted
        case <-p.quit:
            break out
        }
    }

clean:
    // This loop is for draining the output queue and anybody waiting for us
    for {
        select {
        case <-p.outputQueue:
            // TODO
        default:
            break clean
        }
    }
}

// Inbound handler. Inbound messages are received here and passed to the appropriate methods
func (p *Peer) HandleInbound() {

out:
    for atomic.LoadInt32(&p.disconnect) == 0 {
        // Wait for a message from the peer
        msg, err := ethwire.ReadMessage(p.conn)
        if err != nil {
            log.Println(err)

            break out
        }

        if Debug {
            log.Printf("Received %s\n", msg.Type.String())
        }

        switch msg.Type {
        case ethwire.MsgHandshakeTy:
            // Version message
            p.handleHandshake(msg)
        case ethwire.MsgBlockTy:
            err := p.server.blockManager.ProcessBlock(ethutil.NewBlock(msg.Data))
            if err != nil {
                log.Println(err)
            }
        case ethwire.MsgTxTy:
            p.server.txPool.QueueTransaction(ethutil.NewTransactionFromData(msg.Data))
        case ethwire.MsgInvTy:
        case ethwire.MsgGetPeersTy:
            p.requestedPeerList = true
            // Peer asked for list of connected peers
            p.pushPeers()
        case ethwire.MsgPeersTy:
            // Received a list of peers (probably because MsgGetPeersTy was send)
            // Only act on message if we actually requested for a peers list
            if p.requestedPeerList {
                data := ethutil.Conv(msg.Data)
                // Create new list of possible peers for the server to process
                peers := make([]string, data.Length())
                // Parse each possible peer
                for i := 0; i < data.Length(); i++ {
                    peers[i] = data.Get(i).AsString() + strconv.Itoa(int(data.Get(i).AsUint()))
                }

                // Connect to the list of peers
                p.server.ProcessPeerList(peers)
                // Mark unrequested again
                p.requestedPeerList = false
            }
        case ethwire.MsgPingTy:
            // Respond back with pong
            p.QueueMessage(&ethwire.Msg{Type: ethwire.MsgPongTy})
        case ethwire.MsgPongTy:
            p.lastPong = time.Now().Unix()
        }
    }

    p.Stop()
}

func (p *Peer) Start() {
    if !p.inbound {
        err := p.pushHandshake()
        if err != nil {
            log.Printf("Peer can't send outbound version ack", err)

            p.Stop()
        }
    }

    // Run the outbound handler in a new goroutine
    go p.HandleOutbound()
    // Run the inbound handler in a new goroutine
    go p.HandleInbound()
}

func (p *Peer) Stop() {
    if atomic.AddInt32(&p.disconnect, 1) != 1 {
        return
    }

    close(p.quit)
    if atomic.LoadInt32(&p.connected) != 0 {
        p.conn.Close()
    }

    log.Println("Peer shutdown")
}

func (p *Peer) pushHandshake() error {
    msg := ethwire.NewMessage(ethwire.MsgHandshakeTy, ethutil.Encode([]interface{}{
        1, 0, p.server.Nonce,
    }))

    p.QueueMessage(msg)

    return nil
}

// Pushes the list of outbound peers to the client when requested
func (p *Peer) pushPeers() {
    outPeers := make([]interface{}, len(p.server.OutboundPeers()))
    // Serialise each peer
    for i, peer := range p.server.OutboundPeers() {
        outPeers[i] = peer.RlpEncode()
    }

    // Send message to the peer with the known list of connected clients
    msg := ethwire.NewMessage(ethwire.MsgPeersTy, ethutil.Encode(outPeers))

    p.QueueMessage(msg)
}

func (p *Peer) handleHandshake(msg *ethwire.Msg) {
    c := ethutil.Conv(msg.Data)
    // [PROTOCOL_VERSION, NETWORK_ID, CLIENT_ID]
    if c.Get(2).AsUint() == p.server.Nonce {
        //if msg.Nonce == p.server.Nonce {
        log.Println("Peer connected to self, disconnecting")

        p.Stop()

        return
    }

    p.versionKnown = true

    // If this is an inbound connection send an ack back
    if p.inbound {
        err := p.pushHandshake()
        if err != nil {
            log.Println("Peer can't send ack back")

            p.Stop()
        }
    }
}

func (p *Peer) RlpEncode() []byte {
    host, prt, err := net.SplitHostPort(p.conn.RemoteAddr().String())
    if err != nil {
        return nil
    }

    i, err := strconv.Atoi(prt)
    if err != nil {
        return nil
    }

    port := ethutil.NumberToBytes(uint16(i), 16)

    return ethutil.Encode([]interface{}{host, port})
}