whisper: implements ReaderWriter for libp2p streams

This version uses rlp encoding, and is hence an improvement
on the one proposed in #16422.

whisper/whisperv6/libp2p_glue.go

@@ -0,0 +1,87 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package whisperv6
+
+import (
+	"bytes"
+	"io/ioutil"
+	"time"
+	"bufio"
+	"github.com/ethereum/go-ethereum/rlp"
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/p2p"
+	inet "github.com/libp2p/go-libp2p-net"
+)
+
+// LibP2PStream is a wrapper used to implement the MsgReadWriter
+// interface for libp2p's streams.
+type LibP2PStream struct {
+	stream inet.Stream
+}
+
+// serializableP2PMsg is the serializable version of p2p.Msg
+type serializableP2PMsg struct {
+	Code uint64
+	Size uint32
+	Payload []byte
+	ReceivedAt time.Time
+}
+
+// ReadMsg implements the MsgReadWriter interface to read messages
+// from lilbp2p streams.
+func (stream *LibP2PStream) ReadMsg() (p2p.Msg, error) {
+	var m serializableP2PMsg
+	raw, err := rlp.NewStream(bufio.NewReader(stream.stream), 0).Raw()
+	if err != nil {
+		return p2p.Msg{}, fmt.Errorf("Error during RLP decoding of message: %v", err)
+	}
+	err = rlp.DecodeBytes(raw, &m)
+	msg := p2p.Msg{
+		Code: m.Code,
+		Size: m.Size,
+		Payload: bytes.NewReader(m.Payload),
+		ReceivedAt: m.ReceivedAt,
+	}
+	return msg, err
+}
+
+// WriteMsg implements the MsgReadWriter interface to write messages
+// to lilbp2p streams.
+func (stream *LibP2PStream) WriteMsg(msg p2p.Msg) error {
+	payload, err := ioutil.ReadAll(msg.Payload)
+	if err != nil {
+		return fmt.Errorf("Error reading payload: %v", err)
+	}
+	m := serializableP2PMsg {msg.Code, msg.Size, payload, msg.ReceivedAt}
+
+	data, err := rlp.EncodeToBytes(m)
+	if err != nil {
+		return fmt.Errorf("Error encoding to RLP: %v", err)
+	}
+
+	nbytes, err := stream.stream.Write(data)
+	if err != nil {
+		return err
+	}
+
+	if nbytes != len(data) {
+		return fmt.Errorf("Invalid size written in libp2p stream: wrote %d bytes, was expecting %d bytes", nbytes, msg.Size)
+	}
+
+	return nil
+}