forked from foxis/EasyRobot
/
transport.go
210 lines (174 loc) · 3.8 KB
/
transport.go
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package transport
import (
"context"
"errors"
"io"
"unsafe"
)
//go:generate protoc -I=./ -I=${GOPATH}/pkg/mod/ -I=${GOPATH}/src --gogofaster_out=./ types.proto
//go:generate go run ../../../cmd/codegen -i types.pb.go -c ../proto/proto.json -m re
var (
AnyID uint32 = 0xFFFFFFFF
Magic uint32 = 0xBADAB00A
maxHeaderSize = int(unsafe.Sizeof(PacketHeader{}))
BufferSize = maxHeaderSize + 64
errCtxDone = errors.New("context done")
)
func handlePanic(place string) {
if r := recover(); r != nil {
println("Recovering from panic:", r, "@", place)
}
}
// Reliable transport
// Packets always start with header
func ReadPackets(ctx context.Context, id uint32, reader io.Reader) <-chan PacketData {
defer handlePanic("read packets")
channel := make(chan PacketData, 1)
go ReliableStreamReader(ctx, id, reader, channel)
return channel
}
func WritePacket(id, dataType uint32, writer io.Writer, data []byte) error {
packetData := PacketData{
Type: dataType,
Data: data,
}
dataSize := packetData.Size()
packetHeader := PacketHeader{
Magic: Magic,
ID: id,
TailSize: uint32(dataSize),
CRC: 0,
}
headerSize := packetHeader.Size()
dataBuffer := make([]byte, 1+headerSize+dataSize)
dataBuffer[0] = byte(headerSize)
_, err := packetHeader.MarshalTo(dataBuffer[1 : 1+headerSize])
if err != nil {
return err
}
_, err = packetData.MarshalTo(dataBuffer[1+headerSize:])
if err != nil {
return err
}
for {
n, err := writer.Write(dataBuffer)
if err != nil {
return err
}
if n == len(dataBuffer) {
return nil
}
dataBuffer = dataBuffer[n:]
}
}
func ReliableStreamReader(ctx context.Context, id uint32, reader io.Reader, ch chan PacketData) {
defer handlePanic("stream reader")
var (
packet PacketData
err error
buffer = make([]byte, BufferSize)
n int
)
defer close(ch)
for {
buffer, n, packet, err = ReadPacketFromReliableStream(ctx, id, reader, buffer)
if err != nil {
println("read error", err)
return
}
if n == 0 {
continue
}
select {
case ch <- packet:
println("got packet", packet.Type)
default:
println("drop packet", packet.Type)
}
}
}
func ReadPacketFromReliableStream(ctx context.Context, id uint32, reader io.Reader, inbuf []byte) (buffer []byte, np int, tail PacketData, err error) {
defer handlePanic("read packet")
buffer = inbuf
np = 0
n, err := reader.Read(buffer[:1])
if err != nil {
return
}
if n == 0 {
return
}
headerSize := uint32(buffer[0])
if headerSize < 4 || int(headerSize) > maxHeaderSize {
return
}
err = readAll(ctx, reader, buffer[:headerSize])
if err != nil {
return
}
var header PacketHeader
err = header.Unmarshal(buffer[:headerSize])
if err != nil {
return
}
if header.Magic != Magic {
return
}
if id != AnyID && header.ID != id {
err = skipAll(ctx, reader, buffer, int(header.TailSize))
return
}
if header.TailSize > uint32(len(buffer)) {
buffer = make([]byte, header.TailSize)
}
tmp := buffer[:header.TailSize]
err = readAll(ctx, reader, tmp)
if err != nil {
return
}
err = tail.Unmarshal(tmp)
np = int(header.TailSize)
return
}
func skipAll(ctx context.Context, reader io.Reader, buf []byte, bytes int) error {
defer handlePanic("skip all")
for {
if bytes <= 0 {
return nil
}
if len(buf) > bytes {
buf = buf[:bytes]
}
select {
case <-ctx.Done():
return errCtxDone
default:
}
n, err := reader.Read(buf)
if err != nil {
return err
}
bytes -= n
}
}
func readAll(ctx context.Context, reader io.Reader, buf []byte) error {
defer handlePanic("read all")
for {
select {
case <-ctx.Done():
return errCtxDone
default:
}
n, err := reader.Read(buf)
if err != nil {
return err
}
if n == len(buf) {
return nil
}
if n == 0 {
continue
}
buf = buf[n:]
}
}