Add STUN server

Author: pixelbender

LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2016 Vasily Vasilyev
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -2,13 +2,14 @@
 
 [![Build Status](https://travis-ci.org/pixelbender/go-stun.svg)](https://travis-ci.org/pixelbender/go-stun)
 [![Coverage Status](https://coveralls.io/repos/github/pixelbender/go-stun/badge.svg?branch=master)](https://coveralls.io/github/pixelbender/go-stun?branch=master)
+[![Go Report Card](https://goreportcard.com/badge/github.com/pixelbender/go-stun)](https://goreportcard.com/report/github.com/pixelbender/go-stun)
 [![GoDoc](https://godoc.org/github.com/pixelbender/go-stun?status.svg)](https://godoc.org/github.com/pixelbender/go-stun)
 
 There is no working release yet. Stay tuned.
 
 ## Roadmap
 
-- [ ] STUN Message Encoder/Decoder
+- [x] STUN Message Encoder/Decoder
 - [ ] STUN Server
 - [ ] STUN Message integrity check
 - [ ] ICE STUN Attributes

stun/attributes.go

@@ -40,6 +40,7 @@ const (
 // Attribute is the interface that represents a STUN message attribute.
 type Attribute interface {
 	// Encode writes the attribute to the byte array.
+	// Returns io.ErrUnexpectedEOF error if the byte array length is not enough.
 	Encode(b []byte) (int, error)
 }
 
@@ -78,7 +79,7 @@ func (attr ChangeRequest) Encode(b []byte) (int, error) {
 // UnknownAttributes represents the UNKNOWN-ATTRIBUTES attribute
 type UnknownAttributes []uint16
 
-// Encode writes the attribute to the byte array.
+// Encode writes the attribute to the byte array.F
 func (attr UnknownAttributes) Encode(b []byte) (int, error) {
 	n := len(attr) << 1
 	if len(b) < n {

stun/conn.go

@@ -1,13 +1,49 @@
 package stun
 
-import "net"
+import (
+	"bytes"
+	"fmt"
+	"net"
+)
 
 // A Conn represents the STUN agent and implements the STUN protocol over net.Conn interface.
 type Conn struct {
 	net.Conn
+	enc *Encoder
+	dec *Decoder
 }
 
 // NewConn creates a Conn connection on the given net.Conn
 func NewConn(inner net.Conn) *Conn {
-	return &Conn{inner}
+	return &Conn{
+		inner,
+		NewEncoder(inner),
+		NewDecoder(inner),
+	}
+}
+
+// ReadMessage reads STUN messages from the connection.
+func (conn *Conn) ReadMessage() (*Message, error) {
+	return conn.dec.Decode()
+}
+
+// WriteMessage writes STUN messages to the connection.
+func (conn *Conn) WriteMessage(msg *Message) error {
+	return conn.enc.Encode(msg)
+}
+
+// Exchange sends STUN request and returns STUN response or error.
+func (conn *Conn) Exchange(req *Message) (*Message, error) {
+	err := conn.WriteMessage(req)
+	if err != nil {
+		return nil, err
+	}
+	res, err := conn.ReadMessage()
+	if err != nil {
+		return nil, err
+	}
+	if !bytes.Equal(req.Transaction, res.Transaction) {
+		return nil, fmt.Errorf("stun: transaction error")
+	}
+	return res, nil
 }

stun/decoder.go

@@ -1,57 +1,37 @@
 package stun
 
 import (
-	"errors"
+	"bufio"
 	"io"
 )
 
-// ErrWrongFormat is the error returned by ReadMessage when data format is wrong.
-var ErrWrongFormat = errors.New("stun: wrong message format")
-
-// A Decoder reads and decodes STUN messages from the byte array.
+// A Decoder reads and decodes STUN message from an input stream.
 type Decoder struct {
+	buf *bufio.Reader
 }
 
-// ReadMessage reads STUN messages from the byte array.
-func (dec *Decoder) ReadMessage(b []byte) (*Message, error) {
-	if len(b) < 20 {
-		return nil, io.EOF
+// NewDecoder returns a new decoder that reads from r.
+func NewDecoder(r io.Reader) *Decoder {
+	if buf, ok := r.(*bufio.Reader); ok {
+		return &Decoder{buf}
 	}
-	n, p := getInt16(b[2:]), b[20:]
-	if len(p) < n {
-		return nil, io.EOF
+	return &Decoder{bufio.NewReaderSize(r, bufferSize)}
+}
+
+// Decode reads STUN message from the stream.
+func (dec *Decoder) Decode() (*Message, error) {
+	b, err := dec.buf.Peek(20)
+	if err != nil {
+		return nil, err
 	}
-	msg := &Message{
-		Type:       getUint16(b),
-		Cookie:     getUint32(b[4:]),
-		Attributes: make(map[uint16]Attribute),
+	n := getInt16(b[2:]) + 20
+	if b, err = dec.buf.Peek(n); err != nil {
+		return nil, err
 	}
-	copy(msg.Transaction[:], b[8:20])
-	for len(p) > 4 {
-		at, an := getUint16(p), getInt16(p[2:])
-		m := an
-		if mod := n & 3; mod != 0 {
-			m += 4 - mod
-		}
-		if p = p[4:]; len(p) < m {
-			return nil, ErrWrongFormat
-		}
-		msg.Attributes[at], p = RawAttribute(p[:an]), p[an:]
+	msg, err := ReadMessage(b)
+	if err != nil {
+		return nil, err
 	}
-
-	// TODO: check message integrity + fingerprint
-
-	return msg, nil
-}
-
-func getInt16(b []byte) int {
-	return int(b[1]) | int(b[0])<<8
-}
-
-func getUint16(b []byte) uint16 {
-	return uint16(b[1]) | uint16(b[0])<<8
-}
-
-func getUint32(b []byte) uint32 {
-	return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+	dec.buf.Discard(n)
+	return msg, err
 }

stun/encoder.go

@@ -1,90 +1,32 @@
 package stun
 
 import (
-	"fmt"
 	"io"
 )
 
-var defaultBufferSize = 1024
-
-// An Encoder writes and encodes STUN messages to the byte array.
+// An Encoder encodes and writes STUN message to an output stream.
 type Encoder struct {
+	w   io.Writer
 	buf []byte
-	pos int
-}
-
-// Reset resets the encoder buffer to be empty, but it retains the underlying storage for use by future writes.
-func (enc *Encoder) Reset() {
-	enc.pos = 0
 }
 
-// Bytes returns the byte array representation of the encoded messages.
-func (enc *Encoder) Bytes() []byte {
-	return enc.buf[:enc.pos]
+// NewEncoder returns a new encoder that writes to w.
+func NewEncoder(w io.Writer) *Encoder {
+	return &Encoder{w: w}
 }
 
-// WriteMessage writes STUN message to the byte array.
-func (enc *Encoder) WriteMessage(msg *Message) error {
+// Encode writes STUN message to the stream.
+func (enc *Encoder) Encode(msg *Message) error {
 	if enc.buf == nil {
-		enc.buf = make([]byte, 0, defaultBufferSize)
+		enc.buf = make([]byte, bufferSize)
 	}
-	b := enc.buf[enc.pos:]
-	if len(b) < 20 {
-		return io.ErrUnexpectedEOF
+	n, err := msg.Encode(enc.buf)
+	if err != nil {
+		return err
 	}
-	putUint16(b, msg.Type)
-	putUint32(b[4:], msg.Cookie)
-	copy(b[8:], msg.Transaction[:])
-	p := b[20:]
-
-	for at, attr := range msg.Attributes {
-		if attr == nil {
-			return fmt.Errorf("stun: empty attribute 0x%x", at)
-		}
-		if len(p) < 4 {
-			return io.ErrUnexpectedEOF
-		}
-		a := p[4:]
-		n, err := attr.Encode(a)
-		if err != nil {
-			return err
-		}
-		if n < 0 || len(a) < n {
-			return fmt.Errorf("stun: attribute encoding error 0x%x", at)
-		}
-		putUint16(p, at)
-		putInt16(p[2:], n)
-		pad := n
-		if mod := n & 3; mod != 0 {
-			pad += 4 - mod
-		}
-		if len(a) < pad {
-			return io.ErrUnexpectedEOF
-		}
-		for i := n; i < pad; i++ {
-			a[i] = 0
-		}
-		p = a[n:]
+	_, err = enc.w.Write(enc.buf[:n])
+	if err != nil {
+		return err
 	}
-
-	// TODO: create message integrity + fingerprint
-
 	return nil
 }
-
-func putInt16(b []byte, v int) {
-	b[0] = byte(v >> 8)
-	b[1] = byte(v)
-}
-
-func putUint16(b []byte, v uint16) {
-	b[0] = byte(v >> 8)
-	b[1] = byte(v)
-}
-
-func putUint32(b []byte, v uint32) {
-	b[0] = byte(v >> 24)
-	b[1] = byte(v >> 16)
-	b[2] = byte(v >> 8)
-	b[3] = byte(v)
-}