plugeth/eth/protocol.go
Felix Lange eb0e7b1b81 eth, p2p: remove EncodeMsg from p2p.MsgWriter
...and make it a top-level function instead.

The original idea behind having EncodeMsg in the interface was that
implementations might be able to encode RLP data to their underlying
writer directly instead of buffering the encoded data. The encoder
will buffer anyway, so that doesn't matter anymore.

Given the recent problems with EncodeMsg (copy-pasted implementation
bug) I'd rather implement once, correctly.
2015-01-06 12:23:38 +01:00

330 lines
8.6 KiB
Go

package eth
import (
"bytes"
"fmt"
"io"
"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"
)
const (
ProtocolVersion = 51
NetworkId = 0
ProtocolLength = uint64(8)
ProtocolMaxMsgSize = 10 * 1024 * 1024
)
// eth protocol message codes
const (
StatusMsg = iota
GetTxMsg // unused
TxMsg
GetBlockHashesMsg
BlockHashesMsg
GetBlocksMsg
BlocksMsg
NewBlockMsg
)
// 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
}
// 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)
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)
}
// message structs used for rlp decoding
type newBlockMsgData struct {
Block *types.Block
TD *big.Int
}
type getBlockHashesMsgData struct {
Hash []byte
Amount uint64
}
// 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{
Name: "eth",
Version: ProtocolVersion,
Length: ProtocolLength,
Run: func(peer *p2p.Peer, rw p2p.MsgReadWriter) error {
return runEthProtocol(txPool, chainManager, blockPool, peer, rw)
},
}
}
// 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,
id: fmt.Sprintf("%x", peer.Identity().Pubkey()[:8]),
}
err = self.handleStatus()
if err == nil {
for {
err = self.handle()
if err != nil {
self.blockPool.RemovePeer(self.id)
break
}
}
}
return
}
func (self *ethProtocol) handle() error {
msg, err := self.rw.ReadMsg()
if err != nil {
return err
}
if msg.Size > ProtocolMaxMsgSize {
return self.protoError(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
}
// make sure that the payload has been fully consumed
defer msg.Discard()
switch msg.Code {
case StatusMsg:
return self.protoError(ErrExtraStatusMsg, "")
case TxMsg:
// TODO: rework using lazy RLP stream
var txs []*types.Transaction
if err := msg.Decode(&txs); err != nil {
return self.protoError(ErrDecode, "msg %v: %v", msg, err)
}
self.txPool.AddTransactions(txs)
case GetBlockHashesMsg:
var request getBlockHashesMsgData
if err := msg.Decode(&request); err != nil {
return self.protoError(ErrDecode, "->msg %v: %v", msg, err)
}
hashes := self.chainManager.GetBlockHashesFromHash(request.Hash, request.Amount)
return p2p.EncodeMsg(self.rw, BlockHashesMsg, ethutil.ByteSliceToInterface(hashes)...)
case BlockHashesMsg:
// TODO: redo using lazy decode , this way very inefficient on known chains
msgStream := rlp.NewStream(msg.Payload)
var err error
var i int
iter := func() (hash []byte, ok bool) {
hash, err = msgStream.Bytes()
if err == nil {
i++
ok = true
} else {
if err != io.EOF {
self.protoError(ErrDecode, "msg %v: after %v hashes : %v", msg, i, err)
}
}
return
}
self.blockPool.AddBlockHashes(iter, self.id)
case GetBlocksMsg:
msgStream := rlp.NewStream(msg.Payload)
var blocks []interface{}
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)
}
}
block := self.chainManager.GetBlock(hash)
if block != nil {
blocks = append(blocks, block)
}
if i == blockHashesBatchSize {
break
}
}
return p2p.EncodeMsg(self.rw, BlocksMsg, blocks...)
case BlocksMsg:
msgStream := rlp.NewStream(msg.Payload)
for {
var block types.Block
if err := msgStream.Decode(&block); err != nil {
if err == io.EOF {
break
} else {
return self.protoError(ErrDecode, "msg %v: %v", msg, err)
}
}
self.blockPool.AddBlock(&block, self.id)
}
case NewBlockMsg:
var request newBlockMsgData
if err := msg.Decode(&request); err != nil {
return self.protoError(ErrDecode, "msg %v: %v", msg, err)
}
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
iter := func() ([]byte, bool) {
if called {
called = false
return hash, true
} else {
return nil, false
}
}
self.blockPool.AddBlockHashes(iter, self.id)
self.blockPool.AddBlock(request.Block, self.id)
}
default:
return self.protoError(ErrInvalidMsgCode, "%v", msg.Code)
}
return nil
}
type statusMsgData struct {
ProtocolVersion uint32
NetworkId uint32
TD *big.Int
CurrentBlock []byte
GenesisBlock []byte
}
func (self *ethProtocol) statusMsg() p2p.Msg {
td, currentBlock, genesisBlock := self.chainManager.Status()
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 {
return self.protoError(ErrNoStatusMsg, "first msg has code %x (!= %x)", msg.Code, StatusMsg)
}
if msg.Size > ProtocolMaxMsgSize {
return self.protoError(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
}
var status statusMsgData
if err := msg.Decode(&status); err != nil {
return self.protoError(ErrDecode, "msg %v: %v", msg, err)
}
_, _, genesisBlock := self.chainManager.Status()
if bytes.Compare(status.GenesisBlock, genesisBlock) != 0 {
return self.protoError(ErrGenesisBlockMismatch, "%x (!= %x)", status.GenesisBlock, genesisBlock)
}
if status.NetworkId != NetworkId {
return self.protoError(ErrNetworkIdMismatch, "%d (!= %d)", status.NetworkId, NetworkId)
}
if ProtocolVersion != status.ProtocolVersion {
return self.protoError(ErrProtocolVersionMismatch, "%d (!= %d)", status.ProtocolVersion, ProtocolVersion)
}
self.peer.Infof("Peer is [eth] capable (%d/%d). TD=%v H=%x\n", status.ProtocolVersion, status.NetworkId, status.TD, status.CurrentBlock[:4])
self.blockPool.AddPeer(status.TD, status.CurrentBlock, self.id, self.requestBlockHashes, self.requestBlocks, self.protoErrorDisconnect)
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() {
self.peer.Errorln("err %v", err)
// disconnect
} else {
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() {
self.peer.Errorln("err %v", err)
// disconnect
} else {
self.peer.Debugf("fyi %v", err)
}
}