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messagepackhubprotocol.go
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messagepackhubprotocol.go
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package signalr
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"io"
"github.com/go-kit/log"
"github.com/vmihailenco/msgpack/v5"
)
type messagePackHubProtocol struct {
dbg log.Logger
}
func (m *messagePackHubProtocol) ParseMessages(reader io.Reader, remainBuf *bytes.Buffer) ([]interface{}, error) {
frames, err := m.readFrames(reader, remainBuf)
if err != nil {
return nil, err
}
messages := make([]interface{}, 0)
for _, frame := range frames {
message, err := m.parseMessage(bytes.NewBuffer(frame))
if err != nil {
return nil, err
}
messages = append(messages, message)
}
return messages, nil
}
func (m *messagePackHubProtocol) readFrames(reader io.Reader, remainBuf *bytes.Buffer) ([][]byte, error) {
frames := make([][]byte, 0)
for {
// Try to get the frame length
frameLenBuf := make([]byte, binary.MaxVarintLen32)
n1, err := remainBuf.Read(frameLenBuf)
if err != nil && !errors.Is(err, io.EOF) {
// Some weird other error
return nil, err
}
n2, err := reader.Read(frameLenBuf[n1:])
if err != nil && !errors.Is(err, io.EOF) {
// Some weird other error
return nil, err
}
frameLen, lenLen := binary.Uvarint(frameLenBuf[:n1+n2])
if lenLen == 0 {
// reader could not supply enough bytes to decode the Uvarint
// Store the already read bytes in the remainBuf for next iteration
_, _ = remainBuf.Write(frameLenBuf[:n1+n2])
return frames, nil
}
if lenLen < 0 {
return nil, fmt.Errorf("messagepack frame length to large")
}
// Still wondering why this happens, but it happens!
if frameLen == 0 {
// Store the overread bytes for the next iteration
_, _ = remainBuf.Write(frameLenBuf[lenLen:])
continue
}
// Try getting data until at least one frame is available
readBuf := make([]byte, frameLen)
frameBuf := &bytes.Buffer{}
// Did we read too many bytes when detecting the frameLen?
_, _ = frameBuf.Write(frameLenBuf[lenLen:])
// Read the rest of the bytes from the last iteration
_, _ = frameBuf.ReadFrom(remainBuf)
for {
n, err := reader.Read(readBuf)
if errors.Is(err, io.EOF) {
// Less than frameLen. Let the caller parse the already read frames and come here again later
_, _ = remainBuf.ReadFrom(frameBuf)
return frames, nil
}
if err != nil {
return nil, err
}
_, _ = frameBuf.Write(readBuf[:n])
if frameBuf.Len() == int(frameLen) {
// Frame completely read. Return it to the caller
frames = append(frames, frameBuf.Next(int(frameLen)))
return frames, nil
}
if frameBuf.Len() > int(frameLen) {
// More than frameLen. Append the current frame to the result and start reading the next frame
frames = append(frames, frameBuf.Next(int(frameLen)))
_, _ = remainBuf.ReadFrom(frameBuf)
break
}
}
}
}
func (m *messagePackHubProtocol) parseMessage(buf *bytes.Buffer) (interface{}, error) {
decoder := msgpack.NewDecoder(buf)
// Default map decoding expects all maps to have string keys
decoder.SetMapDecoder(func(decoder *msgpack.Decoder) (interface{}, error) {
return decoder.DecodeUntypedMap()
})
msgLen, err := decoder.DecodeArrayLen()
if err != nil {
return nil, err
}
msgType, err := decoder.DecodeInt()
if err != nil {
return nil, err
}
// Ignore Header for all messages, except ping message that has no header
// see message spec at https://github.com/dotnet/aspnetcore/blob/main/src/SignalR/docs/specs/HubProtocol.md#message-headers
if msgType != 6 {
_, err = decoder.DecodeMap()
if err != nil {
return nil, err
}
}
switch msgType {
case 1, 4:
if msgLen < 5 {
return nil, fmt.Errorf("invalid invocationMessage length %v", msgLen)
}
invocationID, err := m.decodeInvocationID(decoder)
if err != nil {
return nil, err
}
invocationMessage := invocationMessage{
Type: msgType,
InvocationID: invocationID,
}
invocationMessage.Target, err = decoder.DecodeString()
if err != nil {
return nil, err
}
argLen, err := decoder.DecodeArrayLen()
if err != nil {
return nil, err
}
for i := 0; i < argLen; i++ {
argument, err := decoder.DecodeRaw()
if err != nil {
return nil, err
}
invocationMessage.Arguments = append(invocationMessage.Arguments, argument)
}
// StreamIds seem to be optional
if msgLen == 6 {
streamIDLen, err := decoder.DecodeArrayLen()
if err != nil {
return nil, err
}
for i := 0; i < streamIDLen; i++ {
streamID, err := decoder.DecodeString()
if err != nil {
return nil, err
}
invocationMessage.StreamIds = append(invocationMessage.StreamIds, streamID)
}
}
return invocationMessage, nil
case 2:
if msgLen != 4 {
return nil, fmt.Errorf("invalid streamItemMessage length %v", msgLen)
}
streamItemMessage := streamItemMessage{Type: 2}
streamItemMessage.InvocationID, err = decoder.DecodeString()
if err != nil {
return nil, err
}
streamItemMessage.Item, err = decoder.DecodeRaw()
if err != nil {
return nil, err
}
return streamItemMessage, nil
case 3:
if msgLen < 4 {
return nil, fmt.Errorf("invalid completionMessage length %v", msgLen)
}
completionMessage := completionMessage{Type: 3}
completionMessage.InvocationID, err = decoder.DecodeString()
if err != nil {
return nil, err
}
resultKind, err := decoder.DecodeInt8()
if err != nil {
return nil, err
}
switch resultKind {
case 1: // Error result
if msgLen < 5 {
return nil, fmt.Errorf("invalid completionMessage length %v", msgLen)
}
completionMessage.Error, err = decoder.DecodeString()
if err != nil {
return nil, err
}
case 2: // Void result
case 3: // Non-void result
if msgLen < 5 {
return nil, fmt.Errorf("invalid completionMessage length %v", msgLen)
}
completionMessage.Result, err = decoder.DecodeRaw()
if err != nil {
return nil, err
}
default:
return nil, fmt.Errorf("invalid resultKind %v", resultKind)
}
return completionMessage, nil
case 5:
if msgLen != 3 {
return nil, fmt.Errorf("invalid cancelInvocationMessage length %v", msgLen)
}
cancelInvocationMessage := cancelInvocationMessage{Type: 5}
cancelInvocationMessage.InvocationID, err = decoder.DecodeString()
if err != nil {
return nil, err
}
return cancelInvocationMessage, nil
case 6:
if msgLen != 1 {
return nil, fmt.Errorf("invalid pingMessage length %v", msgLen)
}
return hubMessage{Type: 6}, nil
case 7:
if msgLen < 2 {
return nil, fmt.Errorf("invalid closeMessage length %v", msgLen)
}
closeMessage := closeMessage{Type: 7}
closeMessage.Error, err = decoder.DecodeString()
if err != nil {
return nil, err
}
if msgLen > 2 {
closeMessage.AllowReconnect, err = decoder.DecodeBool()
if err != nil {
return nil, err
}
}
return closeMessage, nil
}
return msg, nil
}
func (m *messagePackHubProtocol) decodeInvocationID(decoder *msgpack.Decoder) (string, error) {
rawID, err := decoder.DecodeInterface()
if err != nil {
return "", err
}
// nil is ok
if rawID == nil {
return "", nil
}
// Otherwise, it must be string
invocationID, ok := rawID.(string)
if !ok {
return "", fmt.Errorf("invalid InvocationID %#v", rawID)
}
return invocationID, nil
}
func (m *messagePackHubProtocol) WriteMessage(message interface{}, writer io.Writer) error {
// Encode message body
buf := &bytes.Buffer{}
encoder := msgpack.NewEncoder(buf)
// Ensure uppercase/lowercase mapping for struct member names
encoder.SetCustomStructTag("json")
switch msg := message.(type) {
case invocationMessage:
if err := encodeMsgHeader(encoder, 6, msg.Type); err != nil {
return err
}
if msg.InvocationID == "" {
if err := encoder.EncodeNil(); err != nil {
return err
}
} else {
if err := encoder.EncodeString(msg.InvocationID); err != nil {
return err
}
}
if err := encoder.EncodeString(msg.Target); err != nil {
return err
}
if err := encoder.EncodeArrayLen(len(msg.Arguments)); err != nil {
return err
}
for _, arg := range msg.Arguments {
if err := encoder.Encode(arg); err != nil {
return err
}
}
if err := encoder.EncodeArrayLen(len(msg.StreamIds)); err != nil {
return err
}
for _, id := range msg.StreamIds {
if err := encoder.EncodeString(id); err != nil {
return err
}
}
case streamItemMessage:
if err := encodeMsgHeader(encoder, 4, msg.Type); err != nil {
return err
}
if err := encoder.EncodeString(msg.InvocationID); err != nil {
return err
}
if err := encoder.Encode(msg.Item); err != nil {
return err
}
case completionMessage:
msgLen := 4
if msg.Result != nil || msg.Error != "" {
msgLen = 5
}
if err := encodeMsgHeader(encoder, msgLen, msg.Type); err != nil {
return err
}
if err := encoder.EncodeString(msg.InvocationID); err != nil {
return err
}
var resultKind int8 = 2
if msg.Error != "" {
resultKind = 1
} else if msg.Result != nil {
resultKind = 3
}
if err := encoder.EncodeInt8(resultKind); err != nil {
return err
}
switch resultKind {
case 1:
if err := encoder.EncodeString(msg.Error); err != nil {
return err
}
case 3:
if err := encoder.Encode(msg.Result); err != nil {
return err
}
}
case cancelInvocationMessage:
if err := encodeMsgHeader(encoder, 3, msg.Type); err != nil {
return err
}
if err := encoder.EncodeString(msg.InvocationID); err != nil {
return err
}
case hubMessage:
if err := encoder.EncodeArrayLen(1); err != nil {
return err
}
if err := encoder.EncodeInt(6); err != nil {
return err
}
case closeMessage:
if err := encodeMsgHeader(encoder, 3, msg.Type); err != nil {
return err
}
if err := encoder.EncodeString(msg.Error); err != nil {
return err
}
if err := encoder.EncodeBool(msg.AllowReconnect); err != nil {
return err
}
}
// Build frame with length information
frameBuf := &bytes.Buffer{}
lenBuf := make([]byte, binary.MaxVarintLen32)
lenLen := binary.PutUvarint(lenBuf, uint64(buf.Len()))
if _, err := frameBuf.Write(lenBuf[:lenLen]); err != nil {
return err
}
_ = m.dbg.Log(evt, "Write", msg, fmt.Sprintf("%#v", message))
_, _ = frameBuf.ReadFrom(buf)
_, err := frameBuf.WriteTo(writer)
return err
}
func encodeMsgHeader(e *msgpack.Encoder, msgLen int, msgType int) (err error) {
if err = e.EncodeArrayLen(msgLen); err != nil {
return err
}
if err = e.EncodeInt(int64(msgType)); err != nil {
return err
}
headers := make(map[string]interface{})
if err = e.EncodeMap(headers); err != nil {
return err
}
return nil
}
func (m *messagePackHubProtocol) transferMode() TransferMode {
return BinaryTransferMode
}
func (m *messagePackHubProtocol) setDebugLogger(dbg StructuredLogger) {
m.dbg = log.WithPrefix(dbg, "ts", log.DefaultTimestampUTC, "protocol", "MSGP")
}
// UnmarshalArgument unmarshals raw bytes to a destination value. dst is the pointer to the destination value.
func (m *messagePackHubProtocol) UnmarshalArgument(src interface{}, dst interface{}) error {
rawSrc, ok := src.(msgpack.RawMessage)
if !ok {
return fmt.Errorf("invalid source %#v for UnmarshalArgument", src)
}
buf := bytes.NewBuffer(rawSrc)
decoder := msgpack.GetDecoder()
defer msgpack.PutDecoder(decoder)
decoder.Reset(buf)
// Default map decoding expects all maps to have string keys
decoder.SetMapDecoder(func(decoder *msgpack.Decoder) (interface{}, error) {
return decoder.DecodeUntypedMap()
})
// Ensure uppercase/lowercase mapping for struct member names
decoder.SetCustomStructTag("json")
if err := decoder.Decode(dst); err != nil {
return err
}
return nil
}