msg_codec.go

Documentation: go.etcd.io/etcd/server/v3/etcdserver/api/rafthttp

     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  
    15  package rafthttp
    16  
    17  import (
    18  	"encoding/binary"
    19  	"errors"
    20  	"io"
    21  
    22  	"go.etcd.io/etcd/pkg/v3/pbutil"
    23  	"go.etcd.io/etcd/raft/v3/raftpb"
    24  )
    25  
    26  // messageEncoder is a encoder that can encode all kinds of messages.
    27  // It MUST be used with a paired messageDecoder.
    28  type messageEncoder struct {
    29  	w io.Writer
    30  }
    31  
    32  func (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.
    41  type messageDecoder struct {
    42  	r io.Reader
    43  }
    44  
    45  var (
    46  	readBytesLimit     uint64 = 512 * 1024 * 1024 // 512 MB
    47  	ErrExceedSizeLimit        = errors.New("rafthttp: error limit exceeded")
    48  )
    49  
    50  func (dec *messageDecoder) decode() (raftpb.Message, error) {
    51  	return dec.decodeLimit(readBytesLimit)
    52  }
    53  
    54  func (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
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