plugeth/eth/protocol.go

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package eth
import (
"bytes"
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"fmt"
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"io"
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"math/big"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/ethutil"
"github.com/ethereum/go-ethereum/p2p"
"github.com/ethereum/go-ethereum/rlp"
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)
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const (
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ProtocolVersion = 51
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NetworkId = 0
ProtocolLength = uint64(8)
ProtocolMaxMsgSize = 10 * 1024 * 1024
)
// eth protocol message codes
const (
StatusMsg = iota
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GetTxMsg // unused
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TxMsg
GetBlockHashesMsg
BlockHashesMsg
GetBlocksMsg
BlocksMsg
NewBlockMsg
)
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// ethProtocol represents the ethereum wire protocol
// instance is running on each peer
type ethProtocol struct {
txPool txPool
chainManager chainManager
blockPool blockPool
peer *p2p.Peer
id string
rw p2p.MsgReadWriter
}
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// backend is the interface the ethereum protocol backend should implement
// used as an argument to EthProtocol
type txPool interface {
AddTransactions([]*types.Transaction)
}
type chainManager interface {
GetBlockHashesFromHash(hash []byte, amount uint64) (hashes [][]byte)
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GetBlock(hash []byte) (block *types.Block)
Status() (td *big.Int, currentBlock []byte, genesisBlock []byte)
}
type blockPool interface {
AddBlockHashes(next func() ([]byte, bool), peerId string)
AddBlock(block *types.Block, peerId string)
AddPeer(td *big.Int, currentBlock []byte, peerId string, requestHashes func([]byte) error, requestBlocks func([][]byte) error, peerError func(int, string, ...interface{})) (best bool)
RemovePeer(peerId string)
}
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// message structs used for rlp decoding
type newBlockMsgData struct {
Block *types.Block
TD *big.Int
}
type getBlockHashesMsgData struct {
Hash []byte
Amount uint64
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}
// main entrypoint, wrappers starting a server running the eth protocol
// use this constructor to attach the protocol ("class") to server caps
// the Dev p2p layer then runs the protocol instance on each peer
func EthProtocol(txPool txPool, chainManager chainManager, blockPool blockPool) p2p.Protocol {
return p2p.Protocol{
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Name: "eth",
Version: ProtocolVersion,
Length: ProtocolLength,
Run: func(peer *p2p.Peer, rw p2p.MsgReadWriter) error {
return runEthProtocol(txPool, chainManager, blockPool, peer, rw)
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},
}
}
// the main loop that handles incoming messages
// note RemovePeer in the post-disconnect hook
func runEthProtocol(txPool txPool, chainManager chainManager, blockPool blockPool, peer *p2p.Peer, rw p2p.MsgReadWriter) (err error) {
self := &ethProtocol{
txPool: txPool,
chainManager: chainManager,
blockPool: blockPool,
rw: rw,
peer: peer,
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id: fmt.Sprintf("%x", peer.Identity().Pubkey()[:8]),
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}
err = self.handleStatus()
if err == nil {
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for {
err = self.handle()
if err != nil {
self.blockPool.RemovePeer(self.id)
break
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}
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}
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}
return
}
func (self *ethProtocol) handle() error {
msg, err := self.rw.ReadMsg()
if err != nil {
return err
}
if msg.Size > ProtocolMaxMsgSize {
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return self.protoError(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
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}
// make sure that the payload has been fully consumed
defer msg.Discard()
switch msg.Code {
case GetTxMsg: // ignore
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case StatusMsg:
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return self.protoError(ErrExtraStatusMsg, "")
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case TxMsg:
// TODO: rework using lazy RLP stream
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var txs []*types.Transaction
if err := msg.Decode(&txs); err != nil {
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return self.protoError(ErrDecode, "msg %v: %v", msg, err)
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}
self.txPool.AddTransactions(txs)
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case GetBlockHashesMsg:
var request getBlockHashesMsgData
if err := msg.Decode(&request); err != nil {
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return self.protoError(ErrDecode, "->msg %v: %v", msg, err)
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}
hashes := self.chainManager.GetBlockHashesFromHash(request.Hash, request.Amount)
return p2p.EncodeMsg(self.rw, BlockHashesMsg, ethutil.ByteSliceToInterface(hashes)...)
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case BlockHashesMsg:
// TODO: redo using lazy decode , this way very inefficient on known chains
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msgStream := rlp.NewStream(msg.Payload)
var err error
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var i int
iter := func() (hash []byte, ok bool) {
hash, err = msgStream.Bytes()
if err == nil {
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i++
ok = true
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} else {
if err != io.EOF {
self.protoError(ErrDecode, "msg %v: after %v hashes : %v", msg, i, err)
}
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}
return
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}
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self.blockPool.AddBlockHashes(iter, self.id)
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case GetBlocksMsg:
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msgStream := rlp.NewStream(msg.Payload)
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var blocks []interface{}
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var i int
for {
i++
var hash []byte
if err := msgStream.Decode(&hash); err != nil {
if err == io.EOF {
break
} else {
return self.protoError(ErrDecode, "msg %v: %v", msg, err)
}
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}
block := self.chainManager.GetBlock(hash)
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if block != nil {
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blocks = append(blocks, block)
}
if i == blockHashesBatchSize {
break
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}
}
return p2p.EncodeMsg(self.rw, BlocksMsg, blocks...)
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case BlocksMsg:
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msgStream := rlp.NewStream(msg.Payload)
for {
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var block types.Block
if err := msgStream.Decode(&block); err != nil {
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if err == io.EOF {
break
} else {
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return self.protoError(ErrDecode, "msg %v: %v", msg, err)
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}
}
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self.blockPool.AddBlock(&block, self.id)
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}
case NewBlockMsg:
var request newBlockMsgData
if err := msg.Decode(&request); err != nil {
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return self.protoError(ErrDecode, "msg %v: %v", msg, err)
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}
hash := request.Block.Hash()
// to simplify backend interface adding a new block
// uses AddPeer followed by AddHashes, AddBlock only if peer is the best peer
// (or selected as new best peer)
if self.blockPool.AddPeer(request.TD, hash, self.id, self.requestBlockHashes, self.requestBlocks, self.protoErrorDisconnect) {
called := true
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iter := func() ([]byte, bool) {
if called {
called = false
return hash, true
} else {
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return nil, false
}
}
self.blockPool.AddBlockHashes(iter, self.id)
self.blockPool.AddBlock(request.Block, self.id)
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}
default:
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return self.protoError(ErrInvalidMsgCode, "%v", msg.Code)
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}
return nil
}
type statusMsgData struct {
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ProtocolVersion uint32
NetworkId uint32
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TD *big.Int
CurrentBlock []byte
GenesisBlock []byte
}
func (self *ethProtocol) statusMsg() p2p.Msg {
td, currentBlock, genesisBlock := self.chainManager.Status()
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return p2p.NewMsg(StatusMsg,
uint32(ProtocolVersion),
uint32(NetworkId),
td,
currentBlock,
genesisBlock,
)
}
func (self *ethProtocol) handleStatus() error {
// send precanned status message
if err := self.rw.WriteMsg(self.statusMsg()); err != nil {
return err
}
// read and handle remote status
msg, err := self.rw.ReadMsg()
if err != nil {
return err
}
if msg.Code != StatusMsg {
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return self.protoError(ErrNoStatusMsg, "first msg has code %x (!= %x)", msg.Code, StatusMsg)
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}
if msg.Size > ProtocolMaxMsgSize {
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return self.protoError(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
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}
var status statusMsgData
if err := msg.Decode(&status); err != nil {
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return self.protoError(ErrDecode, "msg %v: %v", msg, err)
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}
_, _, genesisBlock := self.chainManager.Status()
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if bytes.Compare(status.GenesisBlock, genesisBlock) != 0 {
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return self.protoError(ErrGenesisBlockMismatch, "%x (!= %x)", status.GenesisBlock, genesisBlock)
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}
if status.NetworkId != NetworkId {
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return self.protoError(ErrNetworkIdMismatch, "%d (!= %d)", status.NetworkId, NetworkId)
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}
if ProtocolVersion != status.ProtocolVersion {
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return self.protoError(ErrProtocolVersionMismatch, "%d (!= %d)", status.ProtocolVersion, ProtocolVersion)
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}
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self.peer.Infof("Peer is [eth] capable (%d/%d). TD=%v H=%x\n", status.ProtocolVersion, status.NetworkId, status.TD, status.CurrentBlock[:4])
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self.blockPool.AddPeer(status.TD, status.CurrentBlock, self.id, self.requestBlockHashes, self.requestBlocks, self.protoErrorDisconnect)
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return nil
}
func (self *ethProtocol) requestBlockHashes(from []byte) error {
self.peer.Debugf("fetching hashes (%d) %x...\n", blockHashesBatchSize, from[0:4])
return p2p.EncodeMsg(self.rw, GetBlockHashesMsg, interface{}(from), uint64(blockHashesBatchSize))
}
func (self *ethProtocol) requestBlocks(hashes [][]byte) error {
self.peer.Debugf("fetching %v blocks", len(hashes))
return p2p.EncodeMsg(self.rw, GetBlocksMsg, ethutil.ByteSliceToInterface(hashes)...)
}
func (self *ethProtocol) protoError(code int, format string, params ...interface{}) (err *protocolError) {
err = ProtocolError(code, format, params...)
if err.Fatal() {
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self.peer.Errorln("err %v", err)
// disconnect
} else {
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self.peer.Debugf("fyi %v", err)
}
return
}
func (self *ethProtocol) protoErrorDisconnect(code int, format string, params ...interface{}) {
err := ProtocolError(code, format, params...)
if err.Fatal() {
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self.peer.Errorln("err %v", err)
// disconnect
} else {
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self.peer.Debugf("fyi %v", err)
}
}