/
frame.go
129 lines (103 loc) · 2.24 KB
/
frame.go
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package stl
import (
"encoding/binary"
"errors"
"fmt"
"io"
)
const (
frameHeaderLength = 1 + 2
maxHandshakeSize = 65536
)
var (
ErrorInvalidFrameType = errors.New("unknown frame type")
)
type Frame struct {
FrameType FrameType
Length uint16
data []byte
}
type FrameType uint8
const (
FrameType_Invalid FrameType = iota
FrameType_InitHello
FrameType_ResponseHello
FrameType_Info
FrameType_Finish
FrameType_Error
FrameType_Data
)
func (f *Frame) ReadFrom(r io.Reader) (int64, error) {
var n int
header := make([]byte, frameHeaderLength)
np, err := io.ReadAtLeast(r, header, len(header))
if err != nil {
return int64(n), err
}
n += np
f.FrameType = FrameType(header[0])
f.Length = binary.BigEndian.Uint16(header[1:])
f.data = make([]byte, f.Length)
np, err = io.ReadAtLeast(r, f.data, int(f.Length))
if err != nil {
return int64(n), err
}
n += np
return int64(n), nil
}
func (f *Frame) MarshalBinary() ([]byte, error) {
d := make([]byte, frameHeaderLength+len(f.data))
d[0] = byte(f.FrameType)
binary.BigEndian.PutUint16(d[1:], uint16(len(f.data)))
copy(d[frameHeaderLength:], f.data)
return d, nil
}
func (f *Frame) Data() (interface{}, error) {
switch f.FrameType {
case FrameType_InitHello:
var ch InitHello
err := ch.Unmarshal(f.data)
return ch, err
case FrameType_ResponseHello:
var ch ResponseHello
err := ch.Unmarshal(f.data)
return ch, err
case FrameType_Info:
var ifr InfoFrame
err := ifr.Unmarshal(f.data)
return ifr, err
case FrameType_Finish:
return nil, nil
case FrameType_Error:
var errf ErrorFrame
err := errf.Unmarshal(f.data)
return errf, err
case FrameType_Data:
return f.data[:f.Length], nil
default:
return nil, ErrorInvalidFrameType
}
}
type Marshaller interface {
Marshal() ([]byte, error)
}
func (f *Frame) Marshal(i Marshaller) ([]byte, error) {
switch v := i.(type) {
case *InitHello:
f.FrameType = FrameType_InitHello
case *ResponseHello:
f.FrameType = FrameType_ResponseHello
case *InfoFrame:
f.FrameType = FrameType_Info
case *ErrorFrame:
f.FrameType = FrameType_Error
default:
return nil, fmt.Errorf("unsupported frame type %T", v)
}
d, err := i.Marshal()
if err != nil {
return nil, err
}
f.data = d
return f.MarshalBinary()
}