/pkg/websocket/client.go
Go | 316 lines | 192 code | 32 blank | 92 comment | 56 complexity | 4b80ebd135834ff70fe47b40cda661ea MD5 | raw file
- // 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 (
- "encoding/binary"
- "bufio"
- "bytes"
- "container/vector"
- "crypto/md5"
- "fmt"
- "http"
- "io"
- "net"
- "os"
- "rand"
- "strings"
- )
- type ProtocolError struct {
- os.ErrorString
- }
- var (
- 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
- )
- 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 is:
- 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) {
- parsedUrl, err := http.ParseURL(url)
- if err != nil {
- return
- }
- client, err := net.Dial("tcp", "", parsedUrl.Host)
- if err != nil {
- return
- }
- return newClient(parsedUrl.RawPath, parsedUrl.Host, origin, url, protocol, client, handshake)
- }
- /*
- 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 /spaces_n/ U+0020 SPACE characters into /key_n/ at random
- // posisions.
- for i := 0; i < spaces; i++ {
- pos := rand.Intn(len(key)-1) + 1
- key = key[0:pos] + " " + key[pos:]
- }
- // 22. 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:]
- }
- 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
- }
- /*
- Gets expected from challenge as described in 4.1 Opening handshake
- Step 42 to 43.
- cf. http://www.whatwg.org/specs/web-socket-protocol/
- */
- func getExpectedForChallenge(number1, number2 uint32, key3 []byte) (expected []byte, err os.Error) {
- // 41. Let /challenge/ be the concatenation of /number_1/, expressed
- // a big-endian 32 bit integer, /number_2/, expressed in a big-
- // endian 32 bit integer, and the eight bytes of /key_3/ in the
- // order they were sent to the wire.
- challenge := make([]byte, 16)
- challengeBuf := bytes.NewBuffer(challenge)
- binary.Write(challengeBuf, binary.BigEndian, number1)
- binary.Write(challengeBuf, binary.BigEndian, number2)
- copy(challenge[8:], key3)
- // 42. Let /expected/ be the MD5 fingerprint of /challenge/ as a big-
- // endian 128 bit string.
- h := md5.New()
- if _, err = h.Write(challenge); err != nil {
- return
- }
- expected = h.Sum()
- 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["Upgrade"] != "WebSocket" ||
- strings.ToLower(resp.Header["Connection"]) != "upgrade" {
- return ErrBadUpgrade
- }
- if resp.Header["Sec-Websocket-Origin"] != origin {
- return ErrBadWebSocketOrigin
- }
- if resp.Header["Sec-Websocket-Location"] != location {
- return ErrBadWebSocketLocation
- }
- if protocol != "" && resp.Header["Sec-Websocket-Protocol"] != protocol {
- return ErrBadWebSocketProtocol
- }
- // Step 42-43. get expected data from challange data.
- expected, err := getExpectedForChallenge(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["Upgrade"] != "WebSocket" ||
- resp.Header["Connection"] != "Upgrade" {
- return ErrBadUpgrade
- }
- if resp.Header["Websocket-Origin"] != origin {
- return ErrBadWebSocketOrigin
- }
- if resp.Header["Websocket-Location"] != location {
- return ErrBadWebSocketLocation
- }
- if protocol != "" && resp.Header["Websocket-Protocol"] != protocol {
- return ErrBadWebSocketProtocol
- }
- return
- }