path: root/peer.go

package main

import (
    "github.com/ethereum/ethutil-go"
    "github.com/ethereum/ethwire-go"
    "log"
    "net"
    "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.InOutMsg
    // 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
}

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

    // 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.InOutMsg) {
    p.outputQueue <- msg
}

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

    if !p.versionKnown {
        switch msg.MsgType {
        case "verack": // 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() {
out:
    for {
        select {
        // Main message queue. All outbound messages are processed through here
        case msg := <-p.outputQueue:
            p.writeMessage(msg)

            p.lastSend = time.Now()
        // 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.MsgType)
        }

        // TODO Hash data and check if for existence (= ignore)

        switch msg.MsgType {
        case "verack":
            // Version message
            p.handleVersionAck(msg)
        case "block":
            err := p.server.blockManager.ProcessBlock(ethutil.NewBlock(msg.Data))
            if err != nil {
                log.Println(err)
            }
        }
    }

    p.Stop()
}

func (p *Peer) Start() {
    if !p.inbound {
        err := p.pushVersionAck()
        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) pushVersionAck() error {
    msg := ethwire.NewMessage("verack", p.server.Nonce, []byte("01"))

    p.QueueMessage(msg)

    return nil
}

func (p *Peer) handleVersionAck(msg *ethwire.InOutMsg) {
    // Detect self connect
    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.pushVersionAck()
        if err != nil {
            log.Println("Peer can't send ack back")

            p.Stop()
        }
    }
}