74 lines
1.6 KiB
Go
74 lines
1.6 KiB
Go
|
package datachannel
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
)
|
||
|
|
|
||
|
|
// message is a parsed DataChannel message
|
||
|
|
type message interface {
|
||
|
|
Marshal() ([]byte, error)
|
||
|
|
Unmarshal([]byte) error
|
||
|
|
}
|
||
|
|
|
||
|
|
// messageType is the first byte in a DataChannel message that specifies type
|
||
|
|
type messageType byte
|
||
|
|
|
||
|
|
// DataChannel Message Types
|
||
|
|
const (
|
||
|
|
dataChannelAck messageType = 0x02
|
||
|
|
dataChannelOpen messageType = 0x03
|
||
|
|
)
|
||
|
|
|
||
|
|
func (t messageType) String() string {
|
||
|
|
switch t {
|
||
|
|
case dataChannelAck:
|
||
|
|
return "DataChannelAck"
|
||
|
|
case dataChannelOpen:
|
||
|
|
return "DataChannelOpen"
|
||
|
|
default:
|
||
|
|
return fmt.Sprintf("Unknown MessageType: %d", t)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// parse accepts raw input and returns a DataChannel message
|
||
|
|
func parse(raw []byte) (message, error) {
|
||
|
|
if len(raw) == 0 {
|
||
|
|
return nil, ErrDataChannelMessageTooShort
|
||
|
|
}
|
||
|
|
|
||
|
|
var msg message
|
||
|
|
switch messageType(raw[0]) {
|
||
|
|
case dataChannelOpen:
|
||
|
|
msg = &channelOpen{}
|
||
|
|
case dataChannelAck:
|
||
|
|
msg = &channelAck{}
|
||
|
|
default:
|
||
|
|
return nil, fmt.Errorf("%w %v", ErrInvalidMessageType, messageType(raw[0]))
|
||
|
|
}
|
||
|
|
|
||
|
|
if err := msg.Unmarshal(raw); err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
|
||
|
|
return msg, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// parseExpectDataChannelOpen parses a DataChannelOpen message
|
||
|
|
// or throws an error
|
||
|
|
func parseExpectDataChannelOpen(raw []byte) (*channelOpen, error) {
|
||
|
|
if len(raw) == 0 {
|
||
|
|
return nil, ErrDataChannelMessageTooShort
|
||
|
|
}
|
||
|
|
|
||
|
|
if actualTyp := messageType(raw[0]); actualTyp != dataChannelOpen {
|
||
|
|
return nil, fmt.Errorf("%w expected(%s) actual(%s)", ErrUnexpectedDataChannelType, actualTyp, dataChannelOpen)
|
||
|
|
}
|
||
|
|
|
||
|
|
msg := &channelOpen{}
|
||
|
|
if err := msg.Unmarshal(raw); err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
|
||
|
|
return msg, nil
|
||
|
|
}
|