1// Copyright 2015 The etcd Authors
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package rafthttp
16
17import (
18	"encoding/binary"
19	"errors"
20	"io"
21
22	"go.etcd.io/etcd/pkg/pbutil"
23	"go.etcd.io/etcd/raft/raftpb"
24)
25
26// messageEncoder is a encoder that can encode all kinds of messages.
27// It MUST be used with a paired messageDecoder.
28type messageEncoder struct {
29	w io.Writer
30}
31
32func (enc *messageEncoder) encode(m *raftpb.Message) error {
33	if err := binary.Write(enc.w, binary.BigEndian, uint64(m.Size())); err != nil {
34		return err
35	}
36	_, err := enc.w.Write(pbutil.MustMarshal(m))
37	return err
38}
39
40// messageDecoder is a decoder that can decode all kinds of messages.
41type messageDecoder struct {
42	r io.Reader
43}
44
45var (
46	readBytesLimit     uint64 = 512 * 1024 * 1024 // 512 MB
47	ErrExceedSizeLimit        = errors.New("rafthttp: error limit exceeded")
48)
49
50func (dec *messageDecoder) decode() (raftpb.Message, error) {
51	return dec.decodeLimit(readBytesLimit)
52}
53
54func (dec *messageDecoder) decodeLimit(numBytes uint64) (raftpb.Message, error) {
55	var m raftpb.Message
56	var l uint64
57	if err := binary.Read(dec.r, binary.BigEndian, &l); err != nil {
58		return m, err
59	}
60	if l > numBytes {
61		return m, ErrExceedSizeLimit
62	}
63	buf := make([]byte, int(l))
64	if _, err := io.ReadFull(dec.r, buf); err != nil {
65		return m, err
66	}
67	return m, m.Unmarshal(buf)
68}
69