1 files changed, 294 insertions, 0 deletions
diff --git a/eth/protocol.go b/eth/protocol.go
new file mode 100644
index 000000000..992fc7550
--- /dev/null
+++ b/eth/protocol.go
@@ -0,0 +1,294 @@
+package eth
+
+import (
+	"bytes"
+	"math"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/ethutil"
+	ethlogger "github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/p2p"
+)
+
+var logger = ethlogger.NewLogger("SERV")
+
+// ethProtocol represents the ethereum wire protocol
+// instance is running on each peer
+type ethProtocol struct {
+	eth  backend
+	td   *big.Int
+	peer *p2p.Peer
+	rw   p2p.MsgReadWriter
+}
+
+// backend is the interface the ethereum protocol backend should implement
+// used as an argument to EthProtocol
+type backend interface {
+	GetTransactions() (txs []*types.Transaction)
+	AddTransactions(txs []*types.Transaction)
+	GetBlockHashes(hash []byte, amount uint32) (hashes [][]byte)
+	AddHash(hash []byte, peer *p2p.Peer) (more bool)
+	GetBlock(hash []byte) (block *types.Block)
+	AddBlock(td *big.Int, block *types.Block, peer *p2p.Peer) (fetchHashes bool, err error)
+	AddPeer(td *big.Int, currentBlock []byte, peer *p2p.Peer) (fetchHashes bool)
+	Status() (td *big.Int, currentBlock []byte, genesisBlock []byte)
+}
+
+const (
+	ProtocolVersion = 43
+	// 0x00 // PoC-1
+	// 0x01 // PoC-2
+	// 0x07 // PoC-3
+	// 0x09 // PoC-4
+	// 0x17 // PoC-5
+	// 0x1c // PoC-6
+	NetworkId          = 0
+	ProtocolLength     = uint64(8)
+	ProtocolMaxMsgSize = 10 * 1024 * 1024
+
+	blockHashesBatchSize = 256
+)
+
+// eth protocol message codes
+const (
+	StatusMsg = iota
+	GetTxMsg  // unused
+	TxMsg
+	GetBlockHashesMsg
+	BlockHashesMsg
+	GetBlocksMsg
+	BlocksMsg
+	NewBlockMsg
+)
+
+// message structs used for rlp decoding
+type newBlockMsgData struct {
+	Block *types.Block
+	TD    *big.Int
+}
+
+type getBlockHashesMsgData struct {
+	Hash   []byte
+	Amount uint32
+}
+
+// main entrypoint, wrappers starting a server running the eth protocol
+// use this constructor to attach the protocol (class) to server caps
+func EthProtocol(eth backend) *p2p.Protocol {
+	return &p2p.Protocol{
+		Name:    "eth",
+		Version: ProtocolVersion,
+		Length:  ProtocolLength,
+		Run: func(peer *p2p.Peer, rw p2p.MsgReadWriter) error {
+			return runEthProtocol(eth, peer, rw)
+		},
+	}
+}
+
+func runEthProtocol(eth backend, peer *p2p.Peer, rw p2p.MsgReadWriter) (err error) {
+	self := &ethProtocol{
+		eth:  eth,
+		rw:   rw,
+		peer: peer,
+	}
+	err = self.handleStatus()
+	if err == nil {
+		go func() {
+			for {
+				err = self.handle()
+				if err != nil {
+					break
+				}
+			}
+		}()
+	}
+	return
+}
+
+func (self *ethProtocol) handle() error {
+	msg, err := self.rw.ReadMsg()
+	if err != nil {
+		return err
+	}
+	if msg.Size > ProtocolMaxMsgSize {
+		return ProtocolError(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
+	}
+	// make sure that the payload has been fully consumed
+	defer msg.Discard()
+
+	switch msg.Code {
+
+	case StatusMsg:
+		return ProtocolError(ErrExtraStatusMsg, "")
+
+	case GetTxMsg:
+		txs := self.eth.GetTransactions()
+		// TODO: rewrite using rlp flat
+		txsInterface := make([]interface{}, len(txs))
+		for i, tx := range txs {
+			txsInterface[i] = tx.RlpData()
+		}
+		return self.rw.EncodeMsg(TxMsg, txsInterface...)
+
+	case TxMsg:
+		var txs []*types.Transaction
+		if err := msg.Decode(&txs); err != nil {
+			return ProtocolError(ErrDecode, "%v", err)
+		}
+		self.eth.AddTransactions(txs)
+
+	case GetBlockHashesMsg:
+		var request getBlockHashesMsgData
+		if err := msg.Decode(&request); err != nil {
+			return ProtocolError(ErrDecode, "%v", err)
+		}
+		hashes := self.eth.GetBlockHashes(request.Hash, request.Amount)
+		return self.rw.EncodeMsg(BlockHashesMsg, ethutil.ByteSliceToInterface(hashes)...)
+
+	case BlockHashesMsg:
+		// TODO: redo using lazy decode , this way very inefficient on known chains
+		// s := rlp.NewListStream(msg.Payload, uint64(msg.Size))
+		var blockHashes [][]byte
+		if err := msg.Decode(&blockHashes); err != nil {
+			return ProtocolError(ErrDecode, "%v", err)
+		}
+		fetchMore := true
+		for _, hash := range blockHashes {
+			fetchMore = self.eth.AddHash(hash, self.peer)
+			if !fetchMore {
+				break
+			}
+		}
+		if fetchMore {
+			return self.FetchHashes(blockHashes[len(blockHashes)-1])
+		}
+
+	case GetBlocksMsg:
+		// Limit to max 300 blocks
+		var blockHashes [][]byte
+		if err := msg.Decode(&blockHashes); err != nil {
+			return ProtocolError(ErrDecode, "%v", err)
+		}
+		max := int(math.Min(float64(len(blockHashes)), 300.0))
+		var blocks []interface{}
+		for i, hash := range blockHashes {
+			if i >= max {
+				break
+			}
+			block := self.eth.GetBlock(hash)
+			if block != nil {
+				blocks = append(blocks, block.Value().Raw())
+			}
+		}
+		return self.rw.EncodeMsg(BlocksMsg, blocks...)
+
+	case BlocksMsg:
+		var blocks []*types.Block
+		if err := msg.Decode(&blocks); err != nil {
+			return ProtocolError(ErrDecode, "%v", err)
+		}
+		for _, block := range blocks {
+			fetchHashes, err := self.eth.AddBlock(nil, block, self.peer)
+			if err != nil {
+				return ProtocolError(ErrInvalidBlock, "%v", err)
+			}
+			if fetchHashes {
+				if err := self.FetchHashes(block.Hash()); err != nil {
+					return err
+				}
+			}
+		}
+
+	case NewBlockMsg:
+		var request newBlockMsgData
+		if err := msg.Decode(&request); err != nil {
+			return ProtocolError(ErrDecode, "%v", err)
+		}
+		var fetchHashes bool
+		// this should reset td and offer blockpool as candidate new peer?
+		if fetchHashes, err = self.eth.AddBlock(request.TD, request.Block, self.peer); err != nil {
+			return ProtocolError(ErrInvalidBlock, "%v", err)
+		}
+		if fetchHashes {
+			return self.FetchHashes(request.Block.Hash())
+		}
+
+	default:
+		return ProtocolError(ErrInvalidMsgCode, "%v", msg.Code)
+	}
+	return nil
+}
+
+type statusMsgData struct {
+	ProtocolVersion uint
+	NetworkId       uint
+	TD              *big.Int
+	CurrentBlock    []byte
+	GenesisBlock    []byte
+}
+
+func (self *ethProtocol) statusMsg() p2p.Msg {
+	td, currentBlock, genesisBlock := self.eth.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 ProtocolError(ErrNoStatusMsg, "first msg has code %x (!= %x)", msg.Code, StatusMsg)
+	}
+
+	if msg.Size > ProtocolMaxMsgSize {
+		return ProtocolError(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
+	}
+
+	var status statusMsgData
+	if err := msg.Decode(&status); err != nil {
+		return ProtocolError(ErrDecode, "%v", err)
+	}
+
+	_, _, genesisBlock := self.eth.Status()
+
+	if bytes.Compare(status.GenesisBlock, genesisBlock) != 0 {
+		return ProtocolError(ErrGenesisBlockMismatch, "%x (!= %x)", status.GenesisBlock, genesisBlock)
+	}
+
+	if status.NetworkId != NetworkId {
+		return ProtocolError(ErrNetworkIdMismatch, "%d (!= %d)", status.NetworkId, NetworkId)
+	}
+
+	if ProtocolVersion != status.ProtocolVersion {
+		return ProtocolError(ErrProtocolVersionMismatch, "%d (!= %d)", status.ProtocolVersion, ProtocolVersion)
+	}
+
+	logger.Infof("Peer is [eth] capable (%d/%d). TD = %v ~ %x", status.ProtocolVersion, status.NetworkId, status.CurrentBlock)
+
+	if self.eth.AddPeer(status.TD, status.CurrentBlock, self.peer) {
+		return self.FetchHashes(status.CurrentBlock)
+	}
+
+	return nil
+}
+
+func (self *ethProtocol) FetchHashes(from []byte) error {
+	logger.Debugf("Fetching hashes (%d) %x...\n", blockHashesBatchSize, from[0:4])
+	return self.rw.EncodeMsg(GetBlockHashesMsg, from, blockHashesBatchSize)
+}