/
handshake.go
50 lines (44 loc) · 1.3 KB
/
handshake.go
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package libproxy
import (
"encoding/binary"
"fmt"
"io"
)
type handshake struct {
// In future we could add flags here for feature negotiation.
// The length is dynamic but it must be < 64k.
payload []byte // uninterpreted
}
const handshakeMagic = "https://github.com/moby/vpnkit multiplexer protocol\n"
func unmarshalHandshake(r io.Reader) (*handshake, error) {
magic := make([]byte, len(handshakeMagic))
if err := binary.Read(r, binary.LittleEndian, &magic); err != nil {
return nil, err
}
if string(magic) != handshakeMagic {
return nil, fmt.Errorf("not a connection to a mulitplexer; received bad magic string '%s'", string(magic))
}
var length uint16
if err := binary.Read(r, binary.LittleEndian, &length); err != nil {
// it will be common to fail here with io.EOF
return nil, err
}
payload := make([]byte, length)
if err := binary.Read(r, binary.LittleEndian, &payload); err != nil {
return nil, err
}
return &handshake{
payload: payload,
}, nil
}
func (h *handshake) Write(w io.Writer) error {
magic := []byte(handshakeMagic)
if err := binary.Write(w, binary.LittleEndian, magic); err != nil {
return err
}
length := uint16(len(h.payload))
if err := binary.Write(w, binary.LittleEndian, length); err != nil {
return err
}
return binary.Write(w, binary.LittleEndian, h.payload)
}