path: root/peer.go

package eth

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

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

// Peer capabillities
type Caps byte

const (
    CapDiscoveryTy = 0x01
    CapTxTy        = 0x02
    CapChainTy     = 0x04

    CapDefault = CapChainTy | CapTxTy | CapDiscoveryTy
)

var capsToString = map[Caps]string{
    CapDiscoveryTy: "Peer discovery",
    CapTxTy:        "Transaction relaying",
    CapChainTy:     "Block chain relaying",
}

func (c Caps) String() string {
    var caps []string
    if c&CapDiscoveryTy > 0 {
        caps = append(caps, capsToString[CapDiscoveryTy])
    }
    if c&CapChainTy > 0 {
        caps = append(caps, capsToString[CapChainTy])
    }
    if c&CapTxTy > 0 {
        caps = append(caps, capsToString[CapTxTy])
    }

    return strings.Join(caps, " | ")
}

type Peer struct {
    // Ethereum interface
    ethereum *Ethereum
    // 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

    // Determines whether this is a seed peer
    seed bool

    host []byte
    port uint16
    caps Caps
}

func NewPeer(conn net.Conn, ethereum *Ethereum, inbound bool) *Peer {
    return &Peer{
        outputQueue: make(chan *ethwire.Msg, outputBufferSize),
        quit:        make(chan bool),
        ethereum:    ethereum,
        conn:        conn,
        inbound:     inbound,
        disconnect:  0,
        connected:   1,
        port:        30303,
    }
}

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

    // Set up the connection in another goroutine so we don't block the main thread
    go func() {
        conn, err := net.DialTimeout("tcp", addr, 30*time.Second)

        if err != nil {
            log.Println("Connection to peer failed", err)
            p.Stop()
            return
        }
        p.conn = conn

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

        p.Start(false)
    }()

    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
    }

    // XXX TMP CODE FOR TESTNET
    switch msg.Type {
    case ethwire.MsgPeersTy:
        if p.seed {
            p.Stop()
        }
    }
}

// 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
    pingTimer := time.NewTicker(2 * time.Minute)
    serviceTimer := time.NewTicker(5 * time.Second)
out:
    for {
        select {
        // Main message queue. All outbound messages are processed through here
        case msg := <-p.outputQueue:
            p.writeMessage(msg)

            p.lastSend = time.Now()

        // Ping timer sends a ping to the peer each 2 minutes
        case <-pingTimer.C:
            p.writeMessage(ethwire.NewMessage(ethwire.MsgPingTy, ""))

        // Service timer takes care of peer broadcasting, transaction
        // posting or block posting
        case <-serviceTimer.C:
            if p.caps&CapDiscoveryTy > 0 {
                msg := p.peersMessage()
                p.ethereum.BroadcastMsg(msg)
            }

        case <-p.quit:
            // Break out of the for loop if a quit message is posted
            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
        msgs, err := ethwire.ReadMessages(p.conn)
        for _, msg := range msgs {
            if err != nil {
                log.Println(err)

                break out
            }

            switch msg.Type {
            case ethwire.MsgHandshakeTy:
                // Version message
                p.handleHandshake(msg)

                p.QueueMessage(ethwire.NewMessage(ethwire.MsgGetPeersTy, ""))
            case ethwire.MsgDiscTy:
                p.Stop()
            case ethwire.MsgPingTy:
                // Respond back with pong
                p.QueueMessage(ethwire.NewMessage(ethwire.MsgPongTy, ""))
            case ethwire.MsgPongTy:
                // If we received a pong back from a peer we set the
                // last pong so the peer handler knows this peer is still
                // active.
                p.lastPong = time.Now().Unix()
            case ethwire.MsgBlockTy:
                // Get all blocks and process them
                msg.Data = msg.Data
                for i := msg.Data.Length() - 1; i >= 0; i-- {
                    block := ethchain.NewBlockFromRlpValue(msg.Data.Get(i))
                    err := p.ethereum.BlockManager.ProcessBlock(block)

                    if err != nil {
                        log.Println(err)
                    }
                }
            case ethwire.MsgTxTy:
                // If the message was a transaction queue the transaction
                // in the TxPool where it will undergo validation and
                // processing when a new block is found
                for i := 0; i < msg.Data.Length(); i++ {
                    p.ethereum.TxPool.QueueTransaction(ethchain.NewTransactionFromRlpValue(msg.Data.Get(i)))
                }
            case ethwire.MsgGetPeersTy:
                // Flag this peer as a 'requested of new peers' this to
                // prevent malicious peers being forced.
                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 := msg.Data
                // Create new list of possible peers for the ethereum to process
                peers := make([]string, data.Length())
                // Parse each possible peer
                for i := 0; i < data.Length(); i++ {
                    peers[i] = unpackAddr(data.Get(i).Get(0), data.Get(i).Get(1).AsUint())
                }

                // Connect to the list of peers
                p.ethereum.ProcessPeerList(peers)
                // Mark unrequested again
                p.requestedPeerList = false

                //}
            case ethwire.MsgGetChainTy:
                var parent *ethchain.Block
                // Length minus one since the very last element in the array is a count
                l := msg.Data.Length() - 1
                // Ignore empty get chains
                if l <= 1 {
                    break
                }

                // Amount of parents in the canonical chain
                amountOfBlocks := msg.Data.Get(l).AsUint()
                // Check each SHA block hash from the message and determine whether
                // the SHA is in the database
                for i := 0; i < l; i++ {
                    if data := msg.Data.Get(i).AsBytes(); p.ethereum.BlockManager.BlockChain().HasBlock(data) {
                        parent = p.ethereum.BlockManager.BlockChain().GetBlock(data)
                        break
                    }
                }

                // If a parent is found send back a reply
                if parent != nil {
                    chain := p.ethereum.BlockManager.BlockChain().GetChainFromHash(parent.Hash(), amountOfBlocks)
                    p.QueueMessage(ethwire.NewMessage(ethwire.MsgBlockTy, append(chain, amountOfBlocks)))
                } else {
                    // If no blocks are found we send back a reply with msg not in chain
                    // and the last hash from get chain
                    lastHash := msg.Data.Get(l - 1)
                    log.Printf("Sending not in chain with hash %x\n", lastHash.AsRaw())
                    p.QueueMessage(ethwire.NewMessage(ethwire.MsgNotInChainTy, []interface{}{lastHash.AsRaw()}))
                }
            case ethwire.MsgNotInChainTy:
                log.Printf("Not in chain %x\n", msg.Data)
                // TODO

                // Unofficial but fun nonetheless
            case ethwire.MsgTalkTy:
                log.Printf("%v says: %s\n", p.conn.RemoteAddr(), msg.Data.AsString())
            }
        }
    }

    p.Stop()
}

func packAddr(address, port string) ([]byte, uint16) {
    addr := strings.Split(address, ".")
    a, _ := strconv.Atoi(addr[0])
    b, _ := strconv.Atoi(addr[1])
    c, _ := strconv.Atoi(addr[2])
    d, _ := strconv.Atoi(addr[3])
    host := []byte{byte(a), byte(b), byte(c), byte(d)}
    prt, _ := strconv.Atoi(port)

    return host, uint16(prt)
}

func unpackAddr(value *ethutil.RlpValue, p uint64) string {
    a := strconv.Itoa(int(value.Get(0).AsUint()))
    b := strconv.Itoa(int(value.Get(1).AsUint()))
    c := strconv.Itoa(int(value.Get(2).AsUint()))
    d := strconv.Itoa(int(value.Get(3).AsUint()))
    host := strings.Join([]string{a, b, c, d}, ".")
    port := strconv.Itoa(int(p))

    return net.JoinHostPort(host, port)
}

func (p *Peer) Start(seed bool) {
    p.seed = seed

    peerHost, peerPort, _ := net.SplitHostPort(p.conn.LocalAddr().String())
    servHost, servPort, _ := net.SplitHostPort(p.conn.RemoteAddr().String())
    if peerHost == servHost {
        log.Println("Connected to self")

        p.Stop()

        return
    }

    if p.inbound {
        p.host, p.port = packAddr(peerHost, peerPort)
    } else {
        p.host, p.port = packAddr(servHost, servPort)
    }

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

        p.Stop()

        return
    }

    // 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.writeMessage(ethwire.NewMessage(ethwire.MsgDiscTy, ""))
        p.conn.Close()
    }

    log.Println("Peer shutdown")
}

func (p *Peer) pushHandshake() error {
    msg := ethwire.NewMessage(ethwire.MsgHandshakeTy, []interface{}{
        uint32(0), uint32(0), "/Ethereum(G) v0.0.1/", p.caps, p.port,
    })

    p.QueueMessage(msg)

    return nil
}

func (p *Peer) peersMessage() *ethwire.Msg {
    outPeers := make([]interface{}, len(p.ethereum.InOutPeers()))
    // Serialise each peer
    for i, peer := range p.ethereum.InOutPeers() {
        outPeers[i] = peer.RlpData()
    }

    // Return the message to the peer with the known list of connected clients
    return ethwire.NewMessage(ethwire.MsgPeersTy, outPeers)
}

// Pushes the list of outbound peers to the client when requested
func (p *Peer) pushPeers() {
    p.QueueMessage(p.peersMessage())
}

func (p *Peer) handleHandshake(msg *ethwire.Msg) {
    c := msg.Data
    // [PROTOCOL_VERSION, NETWORK_ID, CLIENT_ID]
    p.versionKnown = true

    var istr string
    // If this is an inbound connection send an ack back
    if p.inbound {
        if port := c.Get(4).AsUint(); port != 0 {
            p.port = uint16(port)
        }

        istr = "inbound"
    } else {
        msg := ethwire.NewMessage(ethwire.MsgGetChainTy, []interface{}{p.ethereum.BlockManager.BlockChain().CurrentBlock.Hash(), uint64(100)})
        p.QueueMessage(msg)

        istr = "outbound"
    }

    if caps := Caps(c.Get(3).AsByte()); caps != 0 {
        p.caps = caps
    }

    log.Printf("peer connect (%s) %v %s [%s]\n", istr, p.conn.RemoteAddr(), c.Get(2).AsString(), p.caps)
}

func (p *Peer) RlpData() []interface{} {
    return []interface{}{p.host, p.port /*port*/}
}

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})
}