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/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package ttrpc
import (
"bufio"
"encoding/binary"
"fmt"
"io"
"net"
"sync"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
)
const (
messageHeaderLength = 10
messageLengthMax = 4 << 20
)
type messageType uint8
const (
messageTypeRequest messageType = 0x1
messageTypeResponse messageType = 0x2
messageTypeData messageType = 0x3
)
func (mt messageType) String() string {
switch mt {
case messageTypeRequest:
return "request"
case messageTypeResponse:
return "response"
case messageTypeData:
return "data"
default:
return "unknown"
}
}
const (
flagRemoteClosed uint8 = 0x1
flagRemoteOpen uint8 = 0x2
flagNoData uint8 = 0x4
)
// messageHeader represents the fixed-length message header of 10 bytes sent
// with every request.
type messageHeader struct {
Length uint32 // length excluding this header. b[:4]
StreamID uint32 // identifies which request stream message is a part of. b[4:8]
Type messageType // message type b[8]
Flags uint8 // type specific flags b[9]
}
func readMessageHeader(p []byte, r io.Reader) (messageHeader, error) {
_, err := io.ReadFull(r, p[:messageHeaderLength])
if err != nil {
return messageHeader{}, err
}
return messageHeader{
Length: binary.BigEndian.Uint32(p[:4]),
StreamID: binary.BigEndian.Uint32(p[4:8]),
Type: messageType(p[8]),
Flags: p[9],
}, nil
}
func writeMessageHeader(w io.Writer, p []byte, mh messageHeader) error {
binary.BigEndian.PutUint32(p[:4], mh.Length)
binary.BigEndian.PutUint32(p[4:8], mh.StreamID)
p[8] = byte(mh.Type)
p[9] = mh.Flags
_, err := w.Write(p[:])
return err
}
var buffers sync.Pool
type channel struct {
conn net.Conn
bw *bufio.Writer
br *bufio.Reader
hrbuf [messageHeaderLength]byte // avoid alloc when reading header
hwbuf [messageHeaderLength]byte
}
func newChannel(conn net.Conn) *channel {
return &channel{
conn: conn,
bw: bufio.NewWriter(conn),
br: bufio.NewReader(conn),
}
}
// recv a message from the channel. The returned buffer contains the message.
//
// If a valid grpc status is returned, the message header
// returned will be valid and caller should send that along to
// the correct consumer. The bytes on the underlying channel
// will be discarded.
func (ch *channel) recv() (messageHeader, []byte, error) {
mh, err := readMessageHeader(ch.hrbuf[:], ch.br)
if err != nil {
return messageHeader{}, nil, err
}
if mh.Length > uint32(messageLengthMax) {
if _, err := ch.br.Discard(int(mh.Length)); err != nil {
return mh, nil, fmt.Errorf("failed to discard after receiving oversized message: %w", err)
}
return mh, nil, status.Errorf(codes.ResourceExhausted, "message length %v exceed maximum message size of %v", mh.Length, messageLengthMax)
}
var p []byte
if mh.Length > 0 {
p = ch.getmbuf(int(mh.Length))
if _, err := io.ReadFull(ch.br, p); err != nil {
return messageHeader{}, nil, fmt.Errorf("failed reading message: %w", err)
}
}
return mh, p, nil
}
func (ch *channel) send(streamID uint32, t messageType, flags uint8, p []byte) error {
if len(p) > messageLengthMax {
return OversizedMessageError(len(p))
}
if err := writeMessageHeader(ch.bw, ch.hwbuf[:], messageHeader{Length: uint32(len(p)), StreamID: streamID, Type: t, Flags: flags}); err != nil {
return err
}
if len(p) > 0 {
_, err := ch.bw.Write(p)
if err != nil {
return err
}
}
return ch.bw.Flush()
}
func (ch *channel) getmbuf(size int) []byte {
// we can't use the standard New method on pool because we want to allocate
// based on size.
b, ok := buffers.Get().(*[]byte)
if !ok || cap(*b) < size {
// TODO(stevvooe): It may be better to allocate these in fixed length
// buckets to reduce fragmentation but its not clear that would help
// with performance. An ilogb approach or similar would work well.
bb := make([]byte, size)
b = &bb
} else {
*b = (*b)[:size]
}
return *b
}
func (ch *channel) putmbuf(p []byte) {
buffers.Put(&p)
}
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