path: root/peer.go

package eth

import (
    "bytes"
    "container/list"
    "fmt"
    "github.com/ethereum/eth-go/ethchain"
    "github.com/ethereum/eth-go/ethutil"
    "github.com/ethereum/eth-go/ethwire"
    "net"
    "strconv"
    "strings"
    "sync/atomic"
    "time"
)

const (
    // The size of the output buffer for writing messages
    outputBufferSize = 50
    // Current protocol version
    ProtocolVersion = 8
)

type DiscReason byte

const (
    // Values are given explicitly instead of by iota because these values are
    // defined by the wire protocol spec; it is easier for humans to ensure
    // correctness when values are explicit.
    DiscReRequested  = 0x00
    DiscReTcpSysErr  = 0x01
    DiscBadProto     = 0x02
    DiscBadPeer      = 0x03
    DiscTooManyPeers = 0x04
    DiscConnDup      = 0x05
    DiscGenesisErr   = 0x06
    DiscProtoErr     = 0x07
)

var discReasonToString = []string{
    "Disconnect requested",
    "Disconnect TCP sys error",
    "Disconnect bad protocol",
    "Disconnect useless peer",
    "Disconnect too many peers",
    "Disconnect already connected",
    "Disconnect wrong genesis block",
    "Disconnect incompatible network",
}

func (d DiscReason) String() string {
    if len(discReasonToString) < int(d) {
        return "Unknown"
    }

    return discReasonToString[d]
}

// Peer capabilities
type Caps byte

const (
    CapPeerDiscTy = 1 << iota
    CapTxTy
    CapChainTy

    CapDefault = CapChainTy | CapTxTy | CapPeerDiscTy
)

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

func (c Caps) IsCap(cap Caps) bool {
    return c&cap > 0
}

func (c Caps) String() string {
    var caps []string
    if c.IsCap(CapPeerDiscTy) {
        caps = append(caps, capsToString[CapPeerDiscTy])
    }
    if c.IsCap(CapChainTy) {
        caps = append(caps, capsToString[CapChainTy])
    }
    if c.IsCap(CapTxTy) {
        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

    host []interface{}
    port uint16
    caps Caps

    pubkey []byte

    // Indicated whether the node is catching up or not
    catchingUp      bool
    blocksRequested int

    Version string
}

func NewPeer(conn net.Conn, ethereum *Ethereum, inbound bool) *Peer {
    data, _ := ethutil.Config.Db.Get([]byte("KeyRing"))
    pubkey := ethutil.NewValueFromBytes(data).Get(2).Bytes()

    return &Peer{
        outputQueue:     make(chan *ethwire.Msg, outputBufferSize),
        quit:            make(chan bool),
        ethereum:        ethereum,
        conn:            conn,
        inbound:         inbound,
        disconnect:      0,
        connected:       1,
        port:            30303,
        pubkey:          pubkey,
        blocksRequested: 10,
        caps:            ethereum.ServerCaps(),
    }
}

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,
        Version:     ethutil.Config.ClientString,
    }

    // 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 {
            ethutil.Config.Log.Debugln("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()
    }()

    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 {
        ethutil.Config.Log.Debugln("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
    pingTimer := time.NewTicker(2 * time.Minute)
    serviceTimer := time.NewTicker(5 * 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()

        // 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&CapPeerDiscTy > 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() {

    for atomic.LoadInt32(&p.disconnect) == 0 {
        // HMM?
        time.Sleep(500 * time.Millisecond)

        // Wait for a message from the peer
        msgs, err := ethwire.ReadMessages(p.conn)
        if err != nil {
            ethutil.Config.Log.Debugln(err)
        }
        for _, msg := range msgs {
            switch msg.Type {
            case ethwire.MsgHandshakeTy:
                // Version message
                p.handleHandshake(msg)

                if p.caps.IsCap(CapPeerDiscTy) {
                    p.QueueMessage(ethwire.NewMessage(ethwire.MsgGetPeersTy, ""))
                }
            case ethwire.MsgDiscTy:
                p.Stop()
                ethutil.Config.Log.Infoln("Disconnect peer:", DiscReason(msg.Data.Get(0).Uint()))
            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
                var block, lastBlock *ethchain.Block
                var err error

                // 1. Compare the first block over the wire's prev-hash with the hash of your last block
                // 2. If these two values are the same you can just link the chains together.
                // [1:0,2:1,3:2] <- Current blocks (format block:previous_block)
                // [1:0,2:1,3:2,4:3,5:4] <- incoming blocks
                // == [1,2,3,4,5]
                // 3. If the values are not the same we will have to go back and calculate the chain with the highest total difficulty
                // [1:0,2:1,3:2,11:3,12:11,13:12]
                // [1:0,2:1,3:2,4:3,5:4,6:5]

                // [3:2,11:3,12:11,13:12]
                // [3:2,4:3,5:4,6:5]
                // Heb ik dit blok?
                // Nee: heb ik een blok met PrevHash 3?
                // Ja: DIVERSION
                // Nee; Adding to chain

                // See if we can find a common ancestor
                // 1. Get the earliest block in the package.
                // 2. Do we have this block?
                //    3. Yes: Let's continue what we are doing
                //    4. No: Let's request more blocks back.

                // Make sure we are actually receiving anything
                if msg.Data.Len()-1 > 1 && p.catchingUp {
                    // We requested blocks and now we need to make sure we have a common ancestor somewhere in these blocks so we can find
                    // common ground to start syncing from
                    lastBlock = ethchain.NewBlockFromRlpValue(msg.Data.Get(msg.Data.Len() - 1))
                    if !p.ethereum.StateManager().BlockChain().HasBlock(lastBlock.Hash()) {
                        // If we can't find a common ancenstor we need to request more blocks.
                        // FIXME: At one point this won't scale anymore since we are not asking for an offset
                        // we just keep increasing the amount of blocks.
                        //fmt.Println("[PEER] No common ancestor found, requesting more blocks.")
                        p.blocksRequested = p.blocksRequested * 2
                        p.catchingUp = false
                        p.SyncWithBlocks()
                    }

                    for i := msg.Data.Len() - 1; i >= 0; i-- {
                        block = ethchain.NewBlockFromRlpValue(msg.Data.Get(i))
                        // Do we have this block on our chain? If so we can continue
                        if !p.ethereum.StateManager().BlockChain().HasBlock(block.Hash()) {
                            // We don't have this block, but we do have a block with the same prevHash, diversion time!
                            if p.ethereum.StateManager().BlockChain().HasBlockWithPrevHash(block.PrevHash) {
                                //ethutil.Config.Log.Infof("[PEER] Local and foreign chain have diverted after %x, finding best chain!\n", block.PrevHash)
                                if p.ethereum.StateManager().BlockChain().FindCanonicalChainFromMsg(msg, block.PrevHash) {
                                    return
                                }
                            }
                        }
                    }
                }

                for i := msg.Data.Len() - 1; i >= 0; i-- {
                    block = ethchain.NewBlockFromRlpValue(msg.Data.Get(i))

                    p.ethereum.StateManager().PrepareDefault(block)
                    err = p.ethereum.StateManager().ProcessBlock(block, false)

                    if err != nil {
                        if ethutil.Config.Debug {
                            ethutil.Config.Log.Infof("[PEER] Block %x failed\n", block.Hash())
                            ethutil.Config.Log.Infof("[PEER] %v\n", err)
                        }
                        break
                    } else {
                        lastBlock = block
                    }
                }

                if err != nil {
                    // If the parent is unknown try to catch up with this peer
                    if ethchain.IsParentErr(err) {
                        ethutil.Config.Log.Infoln("Attempting to catch up")
                        p.catchingUp = false
                        p.CatchupWithPeer(p.ethereum.BlockChain().CurrentBlock.Hash())
                    } else if ethchain.IsValidationErr(err) {
                        // TODO
                    }
                } else {
                    // XXX Do we want to catch up if there were errors?
                    // If we're catching up, try to catch up further.
                    if p.catchingUp && msg.Data.Len() > 1 {
                        if ethutil.Config.Debug && lastBlock != nil {
                            blockInfo := lastBlock.BlockInfo()
                            ethutil.Config.Log.Infof("Synced to block height #%d %x %x\n", blockInfo.Number, lastBlock.Hash(), blockInfo.Hash)
                        }
                        p.catchingUp = false
                        p.CatchupWithPeer(p.ethereum.BlockChain().CurrentBlock.Hash())
                    }
                }
            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.Len(); i++ {
                    tx := ethchain.NewTransactionFromValue(msg.Data.Get(i))
                    p.ethereum.TxPool().QueueTransaction(tx)
                }
            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.Len())
                    // Parse each possible peer
                    for i := 0; i < data.Len(); i++ {
                        value := data.Get(i)
                        peers[i] = unpackAddr(value.Get(0), value.Get(1).Uint())
                    }

                    // 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.Len() - 1
                // Ignore empty get chains
                if l == 0 {
                    break
                }

                // Amount of parents in the canonical chain
                //amountOfBlocks := msg.Data.Get(l).AsUint()
                amountOfBlocks := uint64(100)

                // 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).Bytes(); p.ethereum.StateManager().BlockChain().HasBlock(data) {
                        parent = p.ethereum.BlockChain().GetBlock(data)
                        break
                    }
                }

                // If a parent is found send back a reply
                if parent != nil {
                    ethutil.Config.Log.Debugf("[PEER] Found conical block, returning chain from: %x ", parent.Hash())
                    chain := p.ethereum.BlockChain().GetChainFromHash(parent.Hash(), amountOfBlocks)
                    if len(chain) > 0 {
                        ethutil.Config.Log.Debugf("[PEER] Returning %d blocks: %x ", len(chain), parent.Hash())
                        p.QueueMessage(ethwire.NewMessage(ethwire.MsgBlockTy, chain))
                    }
                } else {
                    ethutil.Config.Log.Debugf("[PEER] Could not find a similar block")
                    // 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.Raw()}))
                }
            case ethwire.MsgNotInChainTy:
                ethutil.Config.Log.Debugf("Not in chain %x\n", msg.Data)
                // TODO
            case ethwire.MsgGetTxsTy:
                // Get the current transactions of the pool
                txs := p.ethereum.TxPool().CurrentTransactions()
                // Get the RlpData values from the txs
                txsInterface := make([]interface{}, len(txs))
                for i, tx := range txs {
                    txsInterface[i] = tx.RlpData()
                }
                // Broadcast it back to the peer
                p.QueueMessage(ethwire.NewMessage(ethwire.MsgTxTy, txsInterface))

                // Unofficial but fun nonetheless
            case ethwire.MsgTalkTy:
                ethutil.Config.Log.Infoln("%v says: %s\n", p.conn.RemoteAddr(), msg.Data.Str())
            }
        }
    }

    p.Stop()
}

func (p *Peer) Start() {
    peerHost, peerPort, _ := net.SplitHostPort(p.conn.LocalAddr().String())
    servHost, servPort, _ := net.SplitHostPort(p.conn.RemoteAddr().String())

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

    err := p.pushHandshake()
    if err != nil {
        ethutil.Config.Log.Debugln("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()
    }

    // Pre-emptively remove the peer; don't wait for reaping. We already know it's dead if we are here
    p.ethereum.peerMut.Lock()
    defer p.ethereum.peerMut.Unlock()
    eachPeer(p.ethereum.peers, func(peer *Peer, e *list.Element) {
        if peer == p {
            p.ethereum.peers.Remove(e)
        }
    })
}

func (p *Peer) pushHandshake() error {
    data, _ := ethutil.Config.Db.Get([]byte("KeyRing"))
    pubkey := ethutil.NewValueFromBytes(data).Get(2).Bytes()

    msg := ethwire.NewMessage(ethwire.MsgHandshakeTy, []interface{}{
        uint32(ProtocolVersion), uint32(0), p.Version, byte(p.caps), p.port, pubkey,
    })

    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() {
        // Don't return localhost as valid peer
        if !net.ParseIP(peer.conn.RemoteAddr().String()).IsLoopback() {
            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

    if c.Get(0).Uint() != ProtocolVersion {
        ethutil.Config.Log.Debugln("Invalid peer version. Require protocol:", ProtocolVersion)
        p.Stop()
        return
    }

    // [PROTOCOL_VERSION, NETWORK_ID, CLIENT_ID, CAPS, PORT, PUBKEY]
    p.versionKnown = true

    // If this is an inbound connection send an ack back
    if p.inbound {
        p.pubkey = c.Get(5).Bytes()
        p.port = uint16(c.Get(4).Uint())

        // Self connect detection
        key := ethutil.Config.Db.GetKeys()[0]
        if bytes.Compare(key.PublicKey, p.pubkey) == 0 {
            p.Stop()

            return
        }

    }

    // Catch up with the connected peer
    p.SyncWithBlocks()

    // Set the peer's caps
    p.caps = Caps(c.Get(3).Byte())
    // Get a reference to the peers version
    p.Version = c.Get(2).Str()

    ethutil.Config.Log.Debugln("[PEER]", p)
}

func (p *Peer) String() string {
    var strBoundType string
    if p.inbound {
        strBoundType = "inbound"
    } else {
        strBoundType = "outbound"
    }
    var strConnectType string
    if atomic.LoadInt32(&p.disconnect) == 0 {
        strConnectType = "connected"
    } else {
        strConnectType = "disconnected"
    }

    return fmt.Sprintf("[%s] (%s) %v %s [%s]", strConnectType, strBoundType, p.conn.RemoteAddr(), p.Version, p.caps)

}
func (p *Peer) SyncWithBlocks() {
    if !p.catchingUp {
        p.catchingUp = true
        // FIXME: THIS SHOULD NOT BE NEEDED
        if p.blocksRequested == 0 {
            p.blocksRequested = 10
        }
        blocks := p.ethereum.BlockChain().GetChain(p.ethereum.BlockChain().CurrentBlock.Hash(), p.blocksRequested)

        var hashes []interface{}
        for _, block := range blocks {
            hashes = append(hashes, block.Hash())
        }

        msgInfo := append(hashes, uint64(50))

        msg := ethwire.NewMessage(ethwire.MsgGetChainTy, msgInfo)
        p.QueueMessage(msg)
    }
}

func (p *Peer) CatchupWithPeer(blockHash []byte) {
    if !p.catchingUp {
        p.catchingUp = true
        msg := ethwire.NewMessage(ethwire.MsgGetChainTy, []interface{}{blockHash, uint64(50)})
        p.QueueMessage(msg)

        ethutil.Config.Log.Debugf("Requesting blockchain %x...\n", p.ethereum.BlockChain().CurrentBlock.Hash()[:4])

        msg = ethwire.NewMessage(ethwire.MsgGetTxsTy, []interface{}{})
        p.QueueMessage(msg)
        ethutil.Config.Log.Debugln("Requested transactions")
    }
}

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

func packAddr(address, port string) ([]interface{}, 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 := []interface{}{int32(a), int32(b), int32(c), int32(d)}
    prt, _ := strconv.Atoi(port)

    return host, uint16(prt)
}

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

    return net.JoinHostPort(host, port)
}