src/pkg/websocket/client.go - go - Git at Google

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package websocket

 import (
 	"bufio"
 	"bytes"
 	"container/vector"
 	"crypto/tls"
 	"fmt"
 	"http"
 	"io"
 	"net"
 	"os"
 	"rand"
 	"strings"
 )

 type ProtocolError struct {
 	os.ErrorString
 }

 var (
 	ErrBadScheme            = os.ErrorString("bad scheme")
 	ErrBadStatus            = &ProtocolError{"bad status"}
 	ErrBadUpgrade           = &ProtocolError{"missing or bad upgrade"}
 	ErrBadWebSocketOrigin   = &ProtocolError{"missing or bad WebSocket-Origin"}
 	ErrBadWebSocketLocation = &ProtocolError{"missing or bad WebSocket-Location"}
 	ErrBadWebSocketProtocol = &ProtocolError{"missing or bad WebSocket-Protocol"}
 	ErrChallengeResponse    = &ProtocolError{"mismatch challange/response"}
 	secKeyRandomChars       [0x30 - 0x21 + 0x7F - 0x3A]byte
 )

 type DialError struct {
 	URL      string
 	Protocol string
 	Origin   string
 	Error    os.Error
 }

 func (e *DialError) String() string {
 	return "websocket.Dial " + e.URL + ": " + e.Error.String()
 }

 func init() {
 	i := 0
 	for ch := byte(0x21); ch < 0x30; ch++ {
 		secKeyRandomChars[i] = ch
 		i++
 	}
 	for ch := byte(0x3a); ch < 0x7F; ch++ {
 		secKeyRandomChars[i] = ch
 		i++
 	}
 }

 type handshaker func(resourceName, host, origin, location, protocol string, br *bufio.Reader, bw *bufio.Writer) os.Error

 // newClient creates a new Web Socket client connection.
 func newClient(resourceName, host, origin, location, protocol string, rwc io.ReadWriteCloser, handshake handshaker) (ws *Conn, err os.Error) {
 	br := bufio.NewReader(rwc)
 	bw := bufio.NewWriter(rwc)
 	err = handshake(resourceName, host, origin, location, protocol, br, bw)
 	if err != nil {
 		return
 	}
 	buf := bufio.NewReadWriter(br, bw)
 	ws = newConn(origin, location, protocol, buf, rwc)
 	return
 }

 /*
 Dial opens a new client connection to a Web Socket.

 A trivial example client:

 	package main

 	import (
 		"websocket"
 		"strings"
 	)

 	func main() {
 	 	ws, err := websocket.Dial("ws://localhost/ws", "", "http://localhost/");
 	 	if err != nil {
 			panic("Dial: " + err.String())
 		}
 		if _, err := ws.Write([]byte("hello, world!\n")); err != nil {
 			panic("Write: " + err.String())
 		}
 		var msg = make([]byte, 512);
 		if n, err := ws.Read(msg); err != nil {
 			panic("Read: " + err.String())
 		}
 		// use msg[0:n]
 	}
 */
 func Dial(url, protocol, origin string) (ws *Conn, err os.Error) {
 	var client net.Conn

 	parsedUrl, err := http.ParseURL(url)
 	if err != nil {
 		goto Error
 	}

 	switch parsedUrl.Scheme {
 	case "ws":
 		client, err = net.Dial("tcp", "", parsedUrl.Host)

 	case "wss":
 		client, err = tls.Dial("tcp", "", parsedUrl.Host, nil)

 	default:
 		err = ErrBadScheme
 	}
 	if err != nil {
 		goto Error
 	}

 	ws, err = newClient(parsedUrl.RawPath, parsedUrl.Host, origin, url, protocol, client, handshake)
 	if err != nil {
 		goto Error
 	}
 	return

 Error:
 	return nil, &DialError{url, protocol, origin, err}
 }

 /*
 Generates handshake key as described in 4.1 Opening handshake step 16 to 22.
 cf. http://www.whatwg.org/specs/web-socket-protocol/
 */
 func generateKeyNumber() (key string, number uint32) {
 	// 16.  Let /spaces_n/ be a random integer from 1 to 12 inclusive.
 	spaces := rand.Intn(12) + 1

 	// 17. Let /max_n/ be the largest integer not greater than
 	//     4,294,967,295 divided by /spaces_n/
 	max := int(4294967295 / uint32(spaces))

 	// 18. Let /number_n/ be a random integer from 0 to /max_n/ inclusive.
 	number = uint32(rand.Intn(max + 1))

 	// 19. Let /product_n/ be the result of multiplying /number_n/ and
 	//     /spaces_n/ together.
 	product := number * uint32(spaces)

 	// 20. Let /key_n/ be a string consisting of /product_n/, expressed
 	// in base ten using the numerals in the range U+0030 DIGIT ZERO (0)
 	// to U+0039 DIGIT NINE (9).
 	key = fmt.Sprintf("%d", product)

 	// 21. Insert between one and twelve random characters from the ranges
 	//     U+0021 to U+002F and U+003A to U+007E into /key_n/ at random
 	//     positions.
 	n := rand.Intn(12) + 1
 	for i := 0; i < n; i++ {
 		pos := rand.Intn(len(key)) + 1
 		ch := secKeyRandomChars[rand.Intn(len(secKeyRandomChars))]
 		key = key[0:pos] + string(ch) + key[pos:]
 	}

 	// 22. Insert /spaces_n/ U+0020 SPACE characters into /key_n/ at random
 	//     positions other than the start or end of the string.
 	for i := 0; i < spaces; i++ {
 		pos := rand.Intn(len(key)-1) + 1
 		key = key[0:pos] + " " + key[pos:]
 	}

 	return
 }

 /*
 Generates handshake key_3 as described in 4.1 Opening handshake step 26.
 cf. http://www.whatwg.org/specs/web-socket-protocol/
 */
 func generateKey3() (key []byte) {
 	// 26. Let /key3/ be a string consisting of eight random bytes (or
 	//  equivalently, a random 64 bit integer encoded in big-endian order).
 	key = make([]byte, 8)
 	for i := 0; i < 8; i++ {
 		key[i] = byte(rand.Intn(256))
 	}
 	return
 }

 /*
 Web Socket protocol handshake based on
 http://www.whatwg.org/specs/web-socket-protocol/
 (draft of http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol)
 */
 func handshake(resourceName, host, origin, location, protocol string, br *bufio.Reader, bw *bufio.Writer) (err os.Error) {
 	// 4.1. Opening handshake.
 	// Step 5.  send a request line.
 	bw.WriteString("GET " + resourceName + " HTTP/1.1\r\n")

 	// Step 6-14. push request headers in fields.
 	var fields vector.StringVector
 	fields.Push("Upgrade: WebSocket\r\n")
 	fields.Push("Connection: Upgrade\r\n")
 	fields.Push("Host: " + host + "\r\n")
 	fields.Push("Origin: " + origin + "\r\n")
 	if protocol != "" {
 		fields.Push("Sec-WebSocket-Protocol: " + protocol + "\r\n")
 	}
 	// TODO(ukai): Step 15. send cookie if any.

 	// Step 16-23. generate keys and push Sec-WebSocket-Key<n> in fields.
 	key1, number1 := generateKeyNumber()
 	key2, number2 := generateKeyNumber()
 	fields.Push("Sec-WebSocket-Key1: " + key1 + "\r\n")
 	fields.Push("Sec-WebSocket-Key2: " + key2 + "\r\n")

 	// Step 24. shuffle fields and send them out.
 	for i := 1; i < len(fields); i++ {
 		j := rand.Intn(i)
 		fields[i], fields[j] = fields[j], fields[i]
 	}
 	for i := 0; i < len(fields); i++ {
 		bw.WriteString(fields[i])
 	}
 	// Step 25. send CRLF.
 	bw.WriteString("\r\n")

 	// Step 26. genearte 8 bytes random key.
 	key3 := generateKey3()
 	// Step 27. send it out.
 	bw.Write(key3)
 	if err = bw.Flush(); err != nil {
 		return
 	}

 	// Step 28-29, 32-40. read response from server.
 	resp, err := http.ReadResponse(br, "GET")
 	if err != nil {
 		return err
 	}
 	// Step 30. check response code is 101.
 	if resp.StatusCode != 101 {
 		return ErrBadStatus
 	}

 	// Step 41. check websocket headers.
 	if resp.Header.Get("Upgrade") != "WebSocket" ||
 		strings.ToLower(resp.Header.Get("Connection")) != "upgrade" {
 		return ErrBadUpgrade
 	}

 	if resp.Header.Get("Sec-Websocket-Origin") != origin {
 		return ErrBadWebSocketOrigin
 	}

 	if resp.Header.Get("Sec-Websocket-Location") != location {
 		return ErrBadWebSocketLocation
 	}

 	if protocol != "" && resp.Header.Get("Sec-Websocket-Protocol") != protocol {
 		return ErrBadWebSocketProtocol
 	}

 	// Step 42-43. get expected data from challange data.
 	expected, err := getChallengeResponse(number1, number2, key3)
 	if err != nil {
 		return err
 	}

 	// Step 44. read 16 bytes from server.
 	reply := make([]byte, 16)
 	if _, err = io.ReadFull(br, reply); err != nil {
 		return err
 	}

 	// Step 45. check the reply equals to expected data.
 	if !bytes.Equal(expected, reply) {
 		return ErrChallengeResponse
 	}
 	// WebSocket connection is established.
 	return
 }

 /*
 Handhake described in (soon obsolete)
 draft-hixie-thewebsocket-protocol-75.
 */
 func draft75handshake(resourceName, host, origin, location, protocol string, br *bufio.Reader, bw *bufio.Writer) (err os.Error) {
 	bw.WriteString("GET " + resourceName + " HTTP/1.1\r\n")
 	bw.WriteString("Upgrade: WebSocket\r\n")
 	bw.WriteString("Connection: Upgrade\r\n")
 	bw.WriteString("Host: " + host + "\r\n")
 	bw.WriteString("Origin: " + origin + "\r\n")
 	if protocol != "" {
 		bw.WriteString("WebSocket-Protocol: " + protocol + "\r\n")
 	}
 	bw.WriteString("\r\n")
 	bw.Flush()
 	resp, err := http.ReadResponse(br, "GET")
 	if err != nil {
 		return
 	}
 	if resp.Status != "101 Web Socket Protocol Handshake" {
 		return ErrBadStatus
 	}
 	if resp.Header.Get("Upgrade") != "WebSocket" ||
 		resp.Header.Get("Connection") != "Upgrade" {
 		return ErrBadUpgrade
 	}
 	if resp.Header.Get("Websocket-Origin") != origin {
 		return ErrBadWebSocketOrigin
 	}
 	if resp.Header.Get("Websocket-Location") != location {
 		return ErrBadWebSocketLocation
 	}
 	if protocol != "" && resp.Header.Get("Websocket-Protocol") != protocol {
 		return ErrBadWebSocketProtocol
 	}
 	return
 }
	// Copyright 2009 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package websocket

	import (
	"bufio"
	"bytes"
	"container/vector"
	"crypto/tls"
	"fmt"
	"http"
	"io"
	"net"
	"os"
	"rand"
	"strings"
	)

	type ProtocolError struct {
	os.ErrorString
	}

	var (
	ErrBadScheme = os.ErrorString("bad scheme")
	ErrBadStatus = &ProtocolError{"bad status"}
	ErrBadUpgrade = &ProtocolError{"missing or bad upgrade"}
	ErrBadWebSocketOrigin = &ProtocolError{"missing or bad WebSocket-Origin"}
	ErrBadWebSocketLocation = &ProtocolError{"missing or bad WebSocket-Location"}
	ErrBadWebSocketProtocol = &ProtocolError{"missing or bad WebSocket-Protocol"}
	ErrChallengeResponse = &ProtocolError{"mismatch challange/response"}
	secKeyRandomChars [0x30 - 0x21 + 0x7F - 0x3A]byte
	)

	type DialError struct {
	URL string
	Protocol string
	Origin string
	Error os.Error
	}

	func (e *DialError) String() string {
	return "websocket.Dial " + e.URL + ": " + e.Error.String()
	}

	func init() {
	i := 0
	for ch := byte(0x21); ch < 0x30; ch++ {
	secKeyRandomChars[i] = ch
	i++
	}
	for ch := byte(0x3a); ch < 0x7F; ch++ {
	secKeyRandomChars[i] = ch
	i++
	}
	}

	type handshaker func(resourceName, host, origin, location, protocol string, br bufio.Reader, bw bufio.Writer) os.Error

	// newClient creates a new Web Socket client connection.
	func newClient(resourceName, host, origin, location, protocol string, rwc io.ReadWriteCloser, handshake handshaker) (ws *Conn, err os.Error) {
	br := bufio.NewReader(rwc)
	bw := bufio.NewWriter(rwc)
	err = handshake(resourceName, host, origin, location, protocol, br, bw)
	if err != nil {
	return
	}
	buf := bufio.NewReadWriter(br, bw)
	ws = newConn(origin, location, protocol, buf, rwc)
	return
	}

	/*
	Dial opens a new client connection to a Web Socket.

	A trivial example client:

	package main

	import (
	"websocket"
	"strings"
	)

	func main() {
	ws, err := websocket.Dial("ws://localhost/ws", "", "http://localhost/");
	if err != nil {
	panic("Dial: " + err.String())
	}
	if _, err := ws.Write([]byte("hello, world!\n")); err != nil {
	panic("Write: " + err.String())
	}
	var msg = make([]byte, 512);
	if n, err := ws.Read(msg); err != nil {
	panic("Read: " + err.String())
	}
	// use msg[0:n]
	}
	*/
	func Dial(url, protocol, origin string) (ws *Conn, err os.Error) {
	var client net.Conn

	parsedUrl, err := http.ParseURL(url)
	if err != nil {
	goto Error
	}

	switch parsedUrl.Scheme {
	case "ws":
	client, err = net.Dial("tcp", "", parsedUrl.Host)

	case "wss":
	client, err = tls.Dial("tcp", "", parsedUrl.Host, nil)

	default:
	err = ErrBadScheme
	}
	if err != nil {
	goto Error
	}

	ws, err = newClient(parsedUrl.RawPath, parsedUrl.Host, origin, url, protocol, client, handshake)
	if err != nil {
	goto Error
	}
	return

	Error:
	return nil, &DialError{url, protocol, origin, err}
	}

	/*
	Generates handshake key as described in 4.1 Opening handshake step 16 to 22.
	cf. http://www.whatwg.org/specs/web-socket-protocol/
	*/
	func generateKeyNumber() (key string, number uint32) {
	// 16. Let /spaces_n/ be a random integer from 1 to 12 inclusive.
	spaces := rand.Intn(12) + 1

	// 17. Let /max_n/ be the largest integer not greater than
	// 4,294,967,295 divided by /spaces_n/
	max := int(4294967295 / uint32(spaces))

	// 18. Let /number_n/ be a random integer from 0 to /max_n/ inclusive.
	number = uint32(rand.Intn(max + 1))

	// 19. Let /product_n/ be the result of multiplying /number_n/ and
	// /spaces_n/ together.
	product := number * uint32(spaces)

	// 20. Let /key_n/ be a string consisting of /product_n/, expressed
	// in base ten using the numerals in the range U+0030 DIGIT ZERO (0)
	// to U+0039 DIGIT NINE (9).
	key = fmt.Sprintf("%d", product)

	// 21. Insert between one and twelve random characters from the ranges
	// U+0021 to U+002F and U+003A to U+007E into /key_n/ at random
	// positions.
	n := rand.Intn(12) + 1
	for i := 0; i < n; i++ {
	pos := rand.Intn(len(key)) + 1
	ch := secKeyRandomChars[rand.Intn(len(secKeyRandomChars))]
	key = key[0:pos] + string(ch) + key[pos:]
	}

	// 22. Insert /spaces_n/ U+0020 SPACE characters into /key_n/ at random
	// positions other than the start or end of the string.
	for i := 0; i < spaces; i++ {
	pos := rand.Intn(len(key)-1) + 1
	key = key[0:pos] + " " + key[pos:]
	}

	return
	}

	/*
	Generates handshake key_3 as described in 4.1 Opening handshake step 26.
	cf. http://www.whatwg.org/specs/web-socket-protocol/
	*/
	func generateKey3() (key []byte) {
	// 26. Let /key3/ be a string consisting of eight random bytes (or
	// equivalently, a random 64 bit integer encoded in big-endian order).
	key = make([]byte, 8)
	for i := 0; i < 8; i++ {
	key[i] = byte(rand.Intn(256))
	}
	return
	}

	/*
	Web Socket protocol handshake based on
	http://www.whatwg.org/specs/web-socket-protocol/
	(draft of http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol)
	*/
	func handshake(resourceName, host, origin, location, protocol string, br bufio.Reader, bw bufio.Writer) (err os.Error) {
	// 4.1. Opening handshake.
	// Step 5. send a request line.
	bw.WriteString("GET " + resourceName + " HTTP/1.1\r\n")

	// Step 6-14. push request headers in fields.
	var fields vector.StringVector
	fields.Push("Upgrade: WebSocket\r\n")
	fields.Push("Connection: Upgrade\r\n")
	fields.Push("Host: " + host + "\r\n")
	fields.Push("Origin: " + origin + "\r\n")
	if protocol != "" {
	fields.Push("Sec-WebSocket-Protocol: " + protocol + "\r\n")
	}
	// TODO(ukai): Step 15. send cookie if any.

	// Step 16-23. generate keys and push Sec-WebSocket-Key<n> in fields.
	key1, number1 := generateKeyNumber()
	key2, number2 := generateKeyNumber()
	fields.Push("Sec-WebSocket-Key1: " + key1 + "\r\n")
	fields.Push("Sec-WebSocket-Key2: " + key2 + "\r\n")

	// Step 24. shuffle fields and send them out.
	for i := 1; i < len(fields); i++ {
	j := rand.Intn(i)
	fields[i], fields[j] = fields[j], fields[i]
	}
	for i := 0; i < len(fields); i++ {
	bw.WriteString(fields[i])
	}
	// Step 25. send CRLF.
	bw.WriteString("\r\n")

	// Step 26. genearte 8 bytes random key.
	key3 := generateKey3()
	// Step 27. send it out.
	bw.Write(key3)
	if err = bw.Flush(); err != nil {
	return
	}

	// Step 28-29, 32-40. read response from server.
	resp, err := http.ReadResponse(br, "GET")
	if err != nil {
	return err
	}
	// Step 30. check response code is 101.
	if resp.StatusCode != 101 {
	return ErrBadStatus
	}

	// Step 41. check websocket headers.
	if resp.Header.Get("Upgrade") != "WebSocket" \|\|
	strings.ToLower(resp.Header.Get("Connection")) != "upgrade" {
	return ErrBadUpgrade
	}

	if resp.Header.Get("Sec-Websocket-Origin") != origin {
	return ErrBadWebSocketOrigin
	}

	if resp.Header.Get("Sec-Websocket-Location") != location {
	return ErrBadWebSocketLocation
	}

	if protocol != "" && resp.Header.Get("Sec-Websocket-Protocol") != protocol {
	return ErrBadWebSocketProtocol
	}

	// Step 42-43. get expected data from challange data.
	expected, err := getChallengeResponse(number1, number2, key3)
	if err != nil {
	return err
	}

	// Step 44. read 16 bytes from server.
	reply := make([]byte, 16)
	if _, err = io.ReadFull(br, reply); err != nil {
	return err
	}

	// Step 45. check the reply equals to expected data.
	if !bytes.Equal(expected, reply) {
	return ErrChallengeResponse
	}
	// WebSocket connection is established.
	return
	}

	/*
	Handhake described in (soon obsolete)
	draft-hixie-thewebsocket-protocol-75.
	*/
	func draft75handshake(resourceName, host, origin, location, protocol string, br bufio.Reader, bw bufio.Writer) (err os.Error) {
	bw.WriteString("GET " + resourceName + " HTTP/1.1\r\n")
	bw.WriteString("Upgrade: WebSocket\r\n")
	bw.WriteString("Connection: Upgrade\r\n")
	bw.WriteString("Host: " + host + "\r\n")
	bw.WriteString("Origin: " + origin + "\r\n")
	if protocol != "" {
	bw.WriteString("WebSocket-Protocol: " + protocol + "\r\n")
	}
	bw.WriteString("\r\n")
	bw.Flush()
	resp, err := http.ReadResponse(br, "GET")
	if err != nil {
	return
	}
	if resp.Status != "101 Web Socket Protocol Handshake" {
	return ErrBadStatus
	}
	if resp.Header.Get("Upgrade") != "WebSocket" \|\|
	resp.Header.Get("Connection") != "Upgrade" {
	return ErrBadUpgrade
	}
	if resp.Header.Get("Websocket-Origin") != origin {
	return ErrBadWebSocketOrigin
	}
	if resp.Header.Get("Websocket-Location") != location {
	return ErrBadWebSocketLocation
	}
	if protocol != "" && resp.Header.Get("Websocket-Protocol") != protocol {
	return ErrBadWebSocketProtocol
	}
	return
	}