--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pkg/auth/encode.go	Mon Aug 05 16:24:40 2019 +0200
@@ -0,0 +1,102 @@
+// This is Free Software under GNU Affero General Public License v >= 3.0
+// without warranty, see README.md and license for details.
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+// License-Filename: LICENSES/AGPL-3.0.txt
+//
+// Copyright (C) 2018 by via donau
+//   – Österreichische Wasserstraßen-Gesellschaft mbH
+// Software engineering by Intevation GmbH
+//
+// Author(s):
+//  * Sascha L. Teichmann <sascha.teichmann@intevation.de>
+
+package auth
+
+import (
+	"encoding/binary"
+	"io"
+)
+
+// BinReader is a io.Reader to support an error tolerant way
+// to read big endian encoded binary data.
+type BinReader struct {
+	io.Reader
+	// Err is the first encountered error.
+	Err error
+}
+
+// Read implements io.Reader without any endian awareness.
+func (r *BinReader) Read(buf []byte) (int, error) {
+	if r.Err != nil {
+		return 0, r.Err
+	}
+	var n int
+	n, r.Err = r.Read(buf)
+	return n, r.Err
+}
+
+// ReadBin reads big endian encodes binary data into x.
+// If an error was encountered before no data is read.
+func (r *BinReader) ReadBin(x interface{}) {
+	if r.Err == nil {
+		r.Err = binary.Read(r.Reader, binary.BigEndian, x)
+	}
+}
+
+// ReadString reads a big endian encoded string from
+// the underlying io.Reader into *s.
+// If an error was encountered before no data is read
+// and *s is unmodified.
+func (r *BinReader) ReadString(s *string) {
+	if r.Err != nil {
+		return
+	}
+	var l uint32
+	if r.Err = binary.Read(r.Reader, binary.BigEndian, &l); r.Err != nil {
+		return
+	}
+	b := make([]byte, l)
+	if r.Err = binary.Read(r.Reader, binary.BigEndian, b); r.Err != nil {
+		return
+	}
+	*s = string(b)
+}
+
+// BinWriter is a io.Writer to support an error tolerant way
+// to write big endian encoded binary data.
+type BinWriter struct {
+	io.Writer
+	// Err is the first encountered error.
+	Err error
+}
+
+// Write implements io.Writer without any endian awareness.
+func (w *BinWriter) Write(buf []byte) (int, error) {
+	if w.Err != nil {
+		return 0, w.Err
+	}
+	var n int
+	n, w.Err = w.Writer.Write(buf)
+	return n, w.Err
+}
+
+// WriteBin writes x big endian encoded to the underlying io.Writer.
+// If an error was encountered before no data is written.
+func (w *BinWriter) WriteBin(x interface{}) {
+	if w.Err == nil {
+		w.Err = binary.Write(w.Writer, binary.BigEndian, x)
+	}
+}
+
+// WriteString writes a big endian encoded string to
+// the underlying io.Writer.
+// If an error was encountered before no data is written.
+func (w *BinWriter) WriteString(s string) {
+	if w.Err == nil {
+		w.Err = binary.Write(w.Writer, binary.BigEndian, uint32(len(s)))
+	}
+	if w.Err == nil {
+		w.Err = binary.Write(w.Writer, binary.BigEndian, []byte(s))
+	}
+}