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