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package datachannel
import (
"fmt"
"github.com/pkg/errors"
)
// 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, errors.Errorf("DataChannel message is not long enough to determine type ")
}
var msg message
switch messageType(raw[0]) {
case dataChannelOpen:
msg = &channelOpen{}
case dataChannelAck:
msg = &channelAck{}
default:
return nil, errors.Errorf("Unknown MessageType %v", 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, errors.Errorf("the DataChannel message is not long enough to determine type")
}
if actualTyp := messageType(raw[0]); actualTyp != dataChannelOpen {
return nil, errors.Errorf("expected DataChannelOpen but got %s", actualTyp)
}
msg := &channelOpen{}
if err := msg.Unmarshal(raw); err != nil {
return nil, err
}
return msg, nil
}
// parseExpectDataChannelAck parses a DataChannelAck message
// or throws an error
// func parseExpectDataChannelAck(raw []byte) (*channelAck, error) {
// if len(raw) == 0 {
// return nil, errors.Errorf("the DataChannel message is not long enough to determine type")
// }
//
// if actualTyp := messageType(raw[0]); actualTyp != dataChannelAck {
// return nil, errors.Errorf("expected DataChannelAck but got %s", actualTyp)
// }
//
// msg := &channelAck{}
// if err := msg.Unmarshal(raw); err != nil {
// return nil, err
// }
//
// return msg, nil
// }
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