Add doppel and tls packages

mtglib/internal/tls/utils.go

@@ -0,0 +1,48 @@
+package tls
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+func ReadRecord(r io.Reader, w io.Writer) (byte, int64, error) {
+	buf := [SizeHeader]byte{}
+
+	if _, err := io.ReadFull(r, buf[:]); err != nil {
+		return 0, 0, err
+	}
+
+	pVer := buf[SizeRecordType:]
+	pLen := pVer[SizeVersion:]
+
+	if !bytes.Equal(TLSVersion[:], pVer[:SizeVersion]) {
+		return 0, 0, fmt.Errorf("incorrect tls version %v", pVer)
+	}
+
+	length := int64(binary.BigEndian.Uint16(pLen[:SizeSize]))
+	_, err := io.CopyN(w, r, length)
+
+	return buf[0], length, err
+}
+
+func WriteRecord(w io.Writer, payload []byte) error {
+	buf := [MaxRecordSize]byte{}
+	buf[0] = TypeApplicationData
+
+	bufV := buf[SizeRecordType:]
+	copy(bufV[:SizeVersion], TLSVersion[:])
+
+	bufS := bufV[SizeVersion:]
+	binary.BigEndian.PutUint16(bufS[:SizeSize], uint16(len(payload)))
+
+	bufP := buf[SizeHeader:]
+	if n := copy(bufP, payload); n != len(payload) {
+		return fmt.Errorf("copied %d bytes of payload instead of %d", n, len(payload))
+	}
+
+	_, err := w.Write(buf[:SizeHeader+len(payload)])
+
+	return err
+}