91 lines
1.8 KiB
Go
91 lines
1.8 KiB
Go
package main
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import (
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"encoding/binary"
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"io"
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)
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type Typed interface {
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Type() uint32
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}
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type Framed interface {
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Value() []byte
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}
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type Frame interface {
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Typed
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Framed
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}
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type frame struct {
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typeID uint32
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valueBytes []byte
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}
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func (f frame) Type() uint32 {
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return f.typeID
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}
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func (f frame) Value() []byte {
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return f.valueBytes
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}
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// FrameReadWriter is a struct encapsulating io.ReadWriter, which provides additional methods for reading and
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// writing frames -- messages which have their own type and value byte buffer.
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// Data sent or received using this socket is expected to be encoded in LTV format, which means:
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// L - 4 bytes of frame length, big endian encoded
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// T - 4 bytes of frame type, big endian encoded
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// V - L bytes of frame data bytes
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type FrameReadWriter struct {
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io.ReadWriter
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}
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func (frw FrameReadWriter) ReadFrame() (Frame, error) {
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lengthBytes := make([]byte, 4)
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_, err := io.ReadFull(frw, lengthBytes)
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if err != nil {
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return nil, err
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}
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frameLength := binary.BigEndian.Uint32(lengthBytes)
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typeBytes := make([]byte, 4)
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_, err = io.ReadFull(frw, typeBytes)
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if err != nil {
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return nil, err
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}
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frameType := binary.LittleEndian.Uint32(typeBytes)
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frameBytes := make([]byte, frameLength)
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_, err = io.ReadFull(frw, frameBytes)
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if err != nil {
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return nil, err
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}
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result := frame{typeID: frameType, valueBytes: frameBytes}
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return result, nil
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}
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func (frw FrameReadWriter) WriteFrame(f Frame) error {
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frameLength := len(f.Value())
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lengthBytes := make([]byte, 4)
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binary.BigEndian.PutUint32(lengthBytes, uint32(frameLength))
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typeBytes := make([]byte, 4)
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binary.BigEndian.PutUint32(typeBytes, f.Type())
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result := make([]byte, 0)
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result = append(result, lengthBytes...)
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result = append(result, typeBytes...)
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result = append(result, f.Value()...)
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_, err := frw.Write(result)
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if err != nil {
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return err
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}
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return nil
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}
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