commit 38c219e18648327e5ed1afa98aa939ce37ca3cd6
Author: David Fifield <[email protected]>
Date: Sun Aug 11 18:41:22 2013 -0700
Move websocket into its own package.
---
.../src/websocket-server/websocket-server.go | 11 +-
.../src/websocket-server/websocket.go | 432 --------------------
websocket-transport/src/websocket/websocket.go | 432 ++++++++++++++++++++
3 files changed, 438 insertions(+), 437 deletions(-)
diff --git a/websocket-transport/src/websocket-server/websocket-server.go
b/websocket-transport/src/websocket-server/websocket-server.go
index 3ea7481..01a6f66 100644
--- a/websocket-transport/src/websocket-server/websocket-server.go
+++ b/websocket-transport/src/websocket-server/websocket-server.go
@@ -20,6 +20,7 @@ import (
)
import "pt"
+import "websocket"
const ptMethodName = "websocket"
const requestTimeout = 10 * time.Second
@@ -59,7 +60,7 @@ func Log(format string, v ...interface{}) {
// io.ReadWriteCloser. It internally takes care of things like base64 encoding
and
// decoding.
type websocketConn struct {
- Ws *Websocket
+ Ws *websocket.Websocket
Base64 bool
messageBuf []byte
}
@@ -67,7 +68,7 @@ type websocketConn struct {
// Implements io.Reader.
func (conn *websocketConn) Read(b []byte) (n int, err error) {
for len(conn.messageBuf) == 0 {
- var m WebsocketMessage
+ var m websocket.WebsocketMessage
m, err = conn.Ws.ReadMessage()
if err != nil {
return
@@ -128,7 +129,7 @@ func (conn *websocketConn) Close() error {
}
// Create a new websocketConn.
-func NewWebsocketConn(ws *Websocket) websocketConn {
+func NewWebsocketConn(ws *websocket.Websocket) websocketConn {
var conn websocketConn
conn.Ws = ws
conn.Base64 = (ws.Subprotocol == "base64")
@@ -164,7 +165,7 @@ func proxy(local *net.TCPConn, conn *websocketConn) {
wg.Wait()
}
-func websocketHandler(ws *Websocket) {
+func websocketHandler(ws *websocket.Websocket) {
// Undo timeouts on HTTP request handling.
ws.Conn.SetDeadline(time.Time{})
conn := NewWebsocketConn(ws)
@@ -189,7 +190,7 @@ func startListener(addr *net.TCPAddr) (*net.TCPListener,
error) {
return nil, err
}
go func() {
- var config WebsocketConfig
+ var config websocket.WebsocketConfig
config.Subprotocols = []string{"base64"}
config.MaxMessageSize = maxMessageSize
s := &http.Server{
diff --git a/websocket-transport/src/websocket-server/websocket.go
b/websocket-transport/src/websocket-server/websocket.go
deleted file mode 100644
index f195828..0000000
--- a/websocket-transport/src/websocket-server/websocket.go
+++ /dev/null
@@ -1,432 +0,0 @@
-// WebSocket library. Only the RFC 6455 variety of WebSocket is supported.
-//
-// Reading and writing is strictly per-frame (or per-message). There is no way
-// to partially read a frame. WebsocketConfig.MaxMessageSize affords control of
-// the maximum buffering of messages.
-//
-// The reason for using this custom implementation instead of
-// code.google.com/p/go.net/websocket is that the latter has problems with long
-// messages and does not support server subprotocols.
-// "Denial of Service Protection in Go HTTP Servers"
-// https://code.google.com/p/go/issues/detail?id=2093
-// "go.websocket: Read/Copy fail with long frames"
-// https://code.google.com/p/go/issues/detail?id=2134
-// http://golang.org/pkg/net/textproto/#pkg-bugs
-// "To let callers manage exposure to denial of service attacks, Reader
should
-// allow them to set and reset a limit on the number of bytes read from the
-// connection."
-// "websocket.Dial doesn't limit response header length as http.Get does"
-//
https://groups.google.com/forum/?fromgroups=#!topic/golang-nuts/2Tge6U8-QYI
-//
-// Example usage:
-//
-// func doSomething(ws *Websocket) {
-// }
-// var config WebsocketConfig
-// config.Subprotocols = []string{"base64"}
-// config.MaxMessageSize = 2500
-// http.Handle("/", config.Handler(doSomething))
-// err = http.ListenAndServe(":8080", nil)
-
-package main
-
-import (
- "bufio"
- "bytes"
- "crypto/rand"
- "crypto/sha1"
- "encoding/base64"
- "encoding/binary"
- "errors"
- "fmt"
- "io"
- "net"
- "net/http"
- "strings"
-)
-
-// Settings for potential WebSocket connections. Subprotocols is a list of
-// supported subprotocols as in RFC 6455 section 1.9. When answering client
-// requests, the first of the client's requests subprotocols that is also in
-// this list (if any) will be used as the subprotocol for the connection.
-// MaxMessageSize is a limit on buffering messages.
-type WebsocketConfig struct {
- Subprotocols []string
- MaxMessageSize int
-}
-
-// Representation of a WebSocket frame. The Payload is always without masking.
-type WebsocketFrame struct {
- Fin bool
- Opcode byte
- Payload []byte
-}
-
-// Return true iff the frame's opcode says it is a control frame.
-func (frame *WebsocketFrame) IsControl() bool {
- return (frame.Opcode & 0x08) != 0
-}
-
-// Representation of a WebSocket message. The Payload is always without
masking.
-type WebsocketMessage struct {
- Opcode byte
- Payload []byte
-}
-
-// A WebSocket connection after hijacking from HTTP.
-type Websocket struct {
- // Conn and ReadWriter from http.ResponseWriter.Hijack.
- Conn net.Conn
- Bufrw *bufio.ReadWriter
- // Whether we are a client or a server has implications for masking.
- IsClient bool
- // Set from a parent WebsocketConfig.
- MaxMessageSize int
- // The single selected subprotocol after negotiation, or "".
- Subprotocol string
- // Buffer for message payloads, which may be interrupted by control
- // messages.
- messageBuf bytes.Buffer
-}
-
-func applyMask(payload []byte, maskKey [4]byte) {
- for i := 0; i < len(payload); i++ {
- payload[i] = payload[i] ^ maskKey[i%4]
- }
-}
-
-func (ws *Websocket) maxMessageSize() int {
- if ws.MaxMessageSize == 0 {
- return 64000
- }
- return ws.MaxMessageSize
-}
-
-// Read a single frame from the WebSocket.
-func (ws *Websocket) ReadFrame() (frame WebsocketFrame, err error) {
- var b byte
- err = binary.Read(ws.Bufrw, binary.BigEndian, &b)
- if err != nil {
- return
- }
- frame.Fin = (b & 0x80) != 0
- frame.Opcode = b & 0x0f
- err = binary.Read(ws.Bufrw, binary.BigEndian, &b)
- if err != nil {
- return
- }
- masked := (b & 0x80) != 0
-
- payloadLen := uint64(b & 0x7f)
- if payloadLen == 126 {
- var short uint16
- err = binary.Read(ws.Bufrw, binary.BigEndian, &short)
- if err != nil {
- return
- }
- payloadLen = uint64(short)
- } else if payloadLen == 127 {
- var long uint64
- err = binary.Read(ws.Bufrw, binary.BigEndian, &long)
- if err != nil {
- return
- }
- payloadLen = long
- }
- if payloadLen > uint64(ws.maxMessageSize()) {
- err = errors.New(fmt.Sprintf("frame payload length of %d
exceeds maximum of %d", payloadLen, ws.MaxMessageSize))
- return
- }
-
- maskKey := [4]byte{}
- if masked {
- if ws.IsClient {
- err = errors.New("client got masked frame")
- return
- }
- err = binary.Read(ws.Bufrw, binary.BigEndian, &maskKey)
- if err != nil {
- return
- }
- } else {
- if !ws.IsClient {
- err = errors.New("server got unmasked frame")
- return
- }
- }
-
- frame.Payload = make([]byte, payloadLen)
- _, err = io.ReadFull(ws.Bufrw, frame.Payload)
- if err != nil {
- return
- }
- if masked {
- applyMask(frame.Payload, maskKey)
- }
-
- return frame, nil
-}
-
-// Read a single message from the WebSocket. Multiple fragmented frames are
-// combined into a single message before being returned. Non-control messages
-// may be interrupted by control frames. The control frames are returned as
-// individual messages before the message that they interrupt.
-func (ws *Websocket) ReadMessage() (message WebsocketMessage, err error) {
- var opcode byte = 0
- for {
- var frame WebsocketFrame
- frame, err = ws.ReadFrame()
- if err != nil {
- return
- }
- if frame.IsControl() {
- if !frame.Fin {
- err = errors.New("control frame has fin bit
unset")
- return
- }
- message.Opcode = frame.Opcode
- message.Payload = frame.Payload
- return message, nil
- }
-
- if opcode == 0 {
- if frame.Opcode == 0 {
- err = errors.New("first frame has opcode 0")
- return
- }
- opcode = frame.Opcode
- } else {
- if frame.Opcode != 0 {
- err = errors.New(fmt.Sprintf("non-first frame
has nonzero opcode %d", frame.Opcode))
- return
- }
- }
- if ws.messageBuf.Len()+len(frame.Payload) > ws.MaxMessageSize {
- err = errors.New(fmt.Sprintf("message payload length of
%d exceeds maximum of %d",
- ws.messageBuf.Len()+len(frame.Payload),
ws.MaxMessageSize))
- return
- }
- ws.messageBuf.Write(frame.Payload)
- if frame.Fin {
- break
- }
- }
- message.Opcode = opcode
- message.Payload = ws.messageBuf.Bytes()
- ws.messageBuf.Reset()
-
- return message, nil
-}
-
-// Write a single frame to the WebSocket stream. Destructively masks payload in
-// place if ws.IsClient. Frames are always unfragmented.
-func (ws *Websocket) WriteFrame(opcode byte, payload []byte) (err error) {
- if opcode >= 16 {
- err = errors.New(fmt.Sprintf("opcode %d is >= 16", opcode))
- return
- }
- ws.Bufrw.WriteByte(0x80 | opcode)
-
- var maskBit byte
- var maskKey [4]byte
- if ws.IsClient {
- _, err = io.ReadFull(rand.Reader, maskKey[:])
- if err != nil {
- return
- }
- applyMask(payload, maskKey)
- maskBit = 0x80
- } else {
- maskBit = 0x00
- }
-
- if len(payload) < 126 {
- ws.Bufrw.WriteByte(maskBit | byte(len(payload)))
- } else if len(payload) <= 0xffff {
- ws.Bufrw.WriteByte(maskBit | 126)
- binary.Write(ws.Bufrw, binary.BigEndian, uint16(len(payload)))
- } else {
- ws.Bufrw.WriteByte(maskBit | 127)
- binary.Write(ws.Bufrw, binary.BigEndian, uint64(len(payload)))
- }
-
- if ws.IsClient {
- _, err = ws.Bufrw.Write(maskKey[:])
- if err != nil {
- return
- }
- }
- _, err = ws.Bufrw.Write(payload)
- if err != nil {
- return
- }
-
- ws.Bufrw.Flush()
-
- return
-}
-
-// Write a single message to the WebSocket stream. Destructively masks payload
-// in place if ws.IsClient. Messages are always sent as a single unfragmented
-// frame.
-func (ws *Websocket) WriteMessage(opcode byte, payload []byte) (err error) {
- return ws.WriteFrame(opcode, payload)
-}
-
-// Split a string on commas and trim whitespace.
-func commaSplit(s string) []string {
- var result []string
- if strings.TrimSpace(s) == "" {
- return result
- }
- for _, e := range strings.Split(s, ",") {
- result = append(result, strings.TrimSpace(e))
- }
- return result
-}
-
-// Returns true iff one of the strings in haystack is needle.
-func containsCase(haystack []string, needle string) bool {
- for _, e := range haystack {
- if strings.ToLower(e) == strings.ToLower(needle) {
- return true
- }
- }
- return false
-}
-
-// One-step SHA-1 hash of a string.
-func sha1Hash(data string) []byte {
- h := sha1.New()
- h.Write([]byte(data))
- return h.Sum(nil)
-}
-
-func httpError(w http.ResponseWriter, bufrw *bufio.ReadWriter, code int) {
- w.Header().Set("Connection", "close")
- bufrw.WriteString(fmt.Sprintf("HTTP/1.0 %d %s\r\n", code,
http.StatusText(code)))
- w.Header().Write(bufrw)
- bufrw.WriteString("\r\n")
- bufrw.Flush()
-}
-
-// An implementation of http.Handler with a WebsocketConfig. The ServeHTTP
-// function calls websocketCallback assuming WebSocket HTTP negotiation is
-// successful.
-type WebSocketHTTPHandler struct {
- Config *WebsocketConfig
- WebsocketCallback func(*Websocket)
-}
-
-// Implements the http.Handler interface.
-func (handler *WebSocketHTTPHandler) ServeHTTP(w http.ResponseWriter, req
*http.Request) {
- conn, bufrw, err := w.(http.Hijacker).Hijack()
- if err != nil {
- http.Error(w, err.Error(), http.StatusInternalServerError)
- return
- }
- defer conn.Close()
-
- // See RFC 6455 section 4.2.1 for this sequence of checks.
-
- // 1. An HTTP/1.1 or higher GET request, including a "Request-URI"...
- if req.Method != "GET" {
- httpError(w, bufrw, http.StatusMethodNotAllowed)
- return
- }
- if req.URL.Path != "/" {
- httpError(w, bufrw, http.StatusNotFound)
- return
- }
- // 2. A |Host| header field containing the server's authority.
- // We deliberately skip this test.
- // 3. An |Upgrade| header field containing the value "websocket",
- // treated as an ASCII case-insensitive value.
- if !containsCase(commaSplit(req.Header.Get("Upgrade")), "websocket") {
- httpError(w, bufrw, http.StatusBadRequest)
- return
- }
- // 4. A |Connection| header field that includes the token "Upgrade",
- // treated as an ASCII case-insensitive value.
- if !containsCase(commaSplit(req.Header.Get("Connection")), "Upgrade") {
- httpError(w, bufrw, http.StatusBadRequest)
- return
- }
- // 5. A |Sec-WebSocket-Key| header field with a base64-encoded value
- // that, when decoded, is 16 bytes in length.
- websocketKey := req.Header.Get("Sec-WebSocket-Key")
- key, err := base64.StdEncoding.DecodeString(websocketKey)
- if err != nil || len(key) != 16 {
- httpError(w, bufrw, http.StatusBadRequest)
- return
- }
- // 6. A |Sec-WebSocket-Version| header field, with a value of 13.
- // We also allow 8 from draft-ietf-hybi-thewebsocketprotocol-10.
- var knownVersions = []string{"8", "13"}
- websocketVersion := req.Header.Get("Sec-WebSocket-Version")
- if !containsCase(knownVersions, websocketVersion) {
- // "If this version does not match a version understood by the
- // server, the server MUST abort the WebSocket handshake
- // described in this section and instead send an appropriate
- // HTTP error code (such as 426 Upgrade Required) and a
- // |Sec-WebSocket-Version| header field indicating the
- // version(s) the server is capable of understanding."
- w.Header().Set("Sec-WebSocket-Version",
strings.Join(knownVersions, ", "))
- httpError(w, bufrw, 426)
- return
- }
- // 7. Optionally, an |Origin| header field.
- // 8. Optionally, a |Sec-WebSocket-Protocol| header field, with a list
of
- // values indicating which protocols the client would like to speak,
ordered
- // by preference.
- clientProtocols := commaSplit(req.Header.Get("Sec-WebSocket-Protocol"))
- // 9. Optionally, a |Sec-WebSocket-Extensions| header field...
- // 10. Optionally, other header fields...
-
- var ws Websocket
- ws.Conn = conn
- ws.Bufrw = bufrw
- ws.IsClient = false
- ws.MaxMessageSize = handler.Config.MaxMessageSize
-
- // See RFC 6455 section 4.2.2, item 5 for these steps.
-
- // 1. A Status-Line with a 101 response code as per RFC 2616.
- bufrw.WriteString(fmt.Sprintf("HTTP/1.0 %d %s\r\n",
http.StatusSwitchingProtocols, http.StatusText(http.StatusSwitchingProtocols)))
- // 2. An |Upgrade| header field with value "websocket" as per RFC 2616.
- w.Header().Set("Upgrade", "websocket")
- // 3. A |Connection| header field with value "Upgrade".
- w.Header().Set("Connection", "Upgrade")
- // 4. A |Sec-WebSocket-Accept| header field. The value of this header
- // field is constructed by concatenating /key/, defined above in step 4
- // in Section 4.2.2, with the string
- // "258EAFA5-E914-47DA-95CA-C5AB0DC85B11", taking the SHA-1 hash of this
- // concatenated value to obtain a 20-byte value and base64-encoding (see
- // Section 4 of [RFC4648]) this 20-byte hash.
- const magicGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
- acceptKey := base64.StdEncoding.EncodeToString(sha1Hash(websocketKey +
magicGUID))
- w.Header().Set("Sec-WebSocket-Accept", acceptKey)
- // 5. Optionally, a |Sec-WebSocket-Protocol| header field, with a value
- // /subprotocol/ as defined in step 4 in Section 4.2.2.
- for _, clientProto := range clientProtocols {
- for _, serverProto := range handler.Config.Subprotocols {
- if clientProto == serverProto {
- ws.Subprotocol = clientProto
- w.Header().Set("Sec-WebSocket-Protocol",
clientProto)
- break
- }
- }
- }
- // 6. Optionally, a |Sec-WebSocket-Extensions| header field...
- w.Header().Write(bufrw)
- bufrw.WriteString("\r\n")
- bufrw.Flush()
-
- // Call the WebSocket-specific handler.
- handler.WebsocketCallback(&ws)
-}
-
-// Return an http.Handler with the given callback function.
-func (config *WebsocketConfig) Handler(callback func(*Websocket)) http.Handler
{
- return &WebSocketHTTPHandler{config, callback}
-}
diff --git a/websocket-transport/src/websocket/websocket.go
b/websocket-transport/src/websocket/websocket.go
new file mode 100644
index 0000000..617b7ff
--- /dev/null
+++ b/websocket-transport/src/websocket/websocket.go
@@ -0,0 +1,432 @@
+// WebSocket library. Only the RFC 6455 variety of WebSocket is supported.
+//
+// Reading and writing is strictly per-frame (or per-message). There is no way
+// to partially read a frame. WebsocketConfig.MaxMessageSize affords control of
+// the maximum buffering of messages.
+//
+// The reason for using this custom implementation instead of
+// code.google.com/p/go.net/websocket is that the latter has problems with long
+// messages and does not support server subprotocols.
+// "Denial of Service Protection in Go HTTP Servers"
+// https://code.google.com/p/go/issues/detail?id=2093
+// "go.websocket: Read/Copy fail with long frames"
+// https://code.google.com/p/go/issues/detail?id=2134
+// http://golang.org/pkg/net/textproto/#pkg-bugs
+// "To let callers manage exposure to denial of service attacks, Reader
should
+// allow them to set and reset a limit on the number of bytes read from the
+// connection."
+// "websocket.Dial doesn't limit response header length as http.Get does"
+//
https://groups.google.com/forum/?fromgroups=#!topic/golang-nuts/2Tge6U8-QYI
+//
+// Example usage:
+//
+// func doSomething(ws *Websocket) {
+// }
+// var config WebsocketConfig
+// config.Subprotocols = []string{"base64"}
+// config.MaxMessageSize = 2500
+// http.Handle("/", config.Handler(doSomething))
+// err = http.ListenAndServe(":8080", nil)
+
+package websocket
+
+import (
+ "bufio"
+ "bytes"
+ "crypto/rand"
+ "crypto/sha1"
+ "encoding/base64"
+ "encoding/binary"
+ "errors"
+ "fmt"
+ "io"
+ "net"
+ "net/http"
+ "strings"
+)
+
+// Settings for potential WebSocket connections. Subprotocols is a list of
+// supported subprotocols as in RFC 6455 section 1.9. When answering client
+// requests, the first of the client's requests subprotocols that is also in
+// this list (if any) will be used as the subprotocol for the connection.
+// MaxMessageSize is a limit on buffering messages.
+type WebsocketConfig struct {
+ Subprotocols []string
+ MaxMessageSize int
+}
+
+// Representation of a WebSocket frame. The Payload is always without masking.
+type WebsocketFrame struct {
+ Fin bool
+ Opcode byte
+ Payload []byte
+}
+
+// Return true iff the frame's opcode says it is a control frame.
+func (frame *WebsocketFrame) IsControl() bool {
+ return (frame.Opcode & 0x08) != 0
+}
+
+// Representation of a WebSocket message. The Payload is always without
masking.
+type WebsocketMessage struct {
+ Opcode byte
+ Payload []byte
+}
+
+// A WebSocket connection after hijacking from HTTP.
+type Websocket struct {
+ // Conn and ReadWriter from http.ResponseWriter.Hijack.
+ Conn net.Conn
+ Bufrw *bufio.ReadWriter
+ // Whether we are a client or a server has implications for masking.
+ IsClient bool
+ // Set from a parent WebsocketConfig.
+ MaxMessageSize int
+ // The single selected subprotocol after negotiation, or "".
+ Subprotocol string
+ // Buffer for message payloads, which may be interrupted by control
+ // messages.
+ messageBuf bytes.Buffer
+}
+
+func applyMask(payload []byte, maskKey [4]byte) {
+ for i := 0; i < len(payload); i++ {
+ payload[i] = payload[i] ^ maskKey[i%4]
+ }
+}
+
+func (ws *Websocket) maxMessageSize() int {
+ if ws.MaxMessageSize == 0 {
+ return 64000
+ }
+ return ws.MaxMessageSize
+}
+
+// Read a single frame from the WebSocket.
+func (ws *Websocket) ReadFrame() (frame WebsocketFrame, err error) {
+ var b byte
+ err = binary.Read(ws.Bufrw, binary.BigEndian, &b)
+ if err != nil {
+ return
+ }
+ frame.Fin = (b & 0x80) != 0
+ frame.Opcode = b & 0x0f
+ err = binary.Read(ws.Bufrw, binary.BigEndian, &b)
+ if err != nil {
+ return
+ }
+ masked := (b & 0x80) != 0
+
+ payloadLen := uint64(b & 0x7f)
+ if payloadLen == 126 {
+ var short uint16
+ err = binary.Read(ws.Bufrw, binary.BigEndian, &short)
+ if err != nil {
+ return
+ }
+ payloadLen = uint64(short)
+ } else if payloadLen == 127 {
+ var long uint64
+ err = binary.Read(ws.Bufrw, binary.BigEndian, &long)
+ if err != nil {
+ return
+ }
+ payloadLen = long
+ }
+ if payloadLen > uint64(ws.maxMessageSize()) {
+ err = errors.New(fmt.Sprintf("frame payload length of %d
exceeds maximum of %d", payloadLen, ws.MaxMessageSize))
+ return
+ }
+
+ maskKey := [4]byte{}
+ if masked {
+ if ws.IsClient {
+ err = errors.New("client got masked frame")
+ return
+ }
+ err = binary.Read(ws.Bufrw, binary.BigEndian, &maskKey)
+ if err != nil {
+ return
+ }
+ } else {
+ if !ws.IsClient {
+ err = errors.New("server got unmasked frame")
+ return
+ }
+ }
+
+ frame.Payload = make([]byte, payloadLen)
+ _, err = io.ReadFull(ws.Bufrw, frame.Payload)
+ if err != nil {
+ return
+ }
+ if masked {
+ applyMask(frame.Payload, maskKey)
+ }
+
+ return frame, nil
+}
+
+// Read a single message from the WebSocket. Multiple fragmented frames are
+// combined into a single message before being returned. Non-control messages
+// may be interrupted by control frames. The control frames are returned as
+// individual messages before the message that they interrupt.
+func (ws *Websocket) ReadMessage() (message WebsocketMessage, err error) {
+ var opcode byte = 0
+ for {
+ var frame WebsocketFrame
+ frame, err = ws.ReadFrame()
+ if err != nil {
+ return
+ }
+ if frame.IsControl() {
+ if !frame.Fin {
+ err = errors.New("control frame has fin bit
unset")
+ return
+ }
+ message.Opcode = frame.Opcode
+ message.Payload = frame.Payload
+ return message, nil
+ }
+
+ if opcode == 0 {
+ if frame.Opcode == 0 {
+ err = errors.New("first frame has opcode 0")
+ return
+ }
+ opcode = frame.Opcode
+ } else {
+ if frame.Opcode != 0 {
+ err = errors.New(fmt.Sprintf("non-first frame
has nonzero opcode %d", frame.Opcode))
+ return
+ }
+ }
+ if ws.messageBuf.Len()+len(frame.Payload) > ws.MaxMessageSize {
+ err = errors.New(fmt.Sprintf("message payload length of
%d exceeds maximum of %d",
+ ws.messageBuf.Len()+len(frame.Payload),
ws.MaxMessageSize))
+ return
+ }
+ ws.messageBuf.Write(frame.Payload)
+ if frame.Fin {
+ break
+ }
+ }
+ message.Opcode = opcode
+ message.Payload = ws.messageBuf.Bytes()
+ ws.messageBuf.Reset()
+
+ return message, nil
+}
+
+// Write a single frame to the WebSocket stream. Destructively masks payload in
+// place if ws.IsClient. Frames are always unfragmented.
+func (ws *Websocket) WriteFrame(opcode byte, payload []byte) (err error) {
+ if opcode >= 16 {
+ err = errors.New(fmt.Sprintf("opcode %d is >= 16", opcode))
+ return
+ }
+ ws.Bufrw.WriteByte(0x80 | opcode)
+
+ var maskBit byte
+ var maskKey [4]byte
+ if ws.IsClient {
+ _, err = io.ReadFull(rand.Reader, maskKey[:])
+ if err != nil {
+ return
+ }
+ applyMask(payload, maskKey)
+ maskBit = 0x80
+ } else {
+ maskBit = 0x00
+ }
+
+ if len(payload) < 126 {
+ ws.Bufrw.WriteByte(maskBit | byte(len(payload)))
+ } else if len(payload) <= 0xffff {
+ ws.Bufrw.WriteByte(maskBit | 126)
+ binary.Write(ws.Bufrw, binary.BigEndian, uint16(len(payload)))
+ } else {
+ ws.Bufrw.WriteByte(maskBit | 127)
+ binary.Write(ws.Bufrw, binary.BigEndian, uint64(len(payload)))
+ }
+
+ if ws.IsClient {
+ _, err = ws.Bufrw.Write(maskKey[:])
+ if err != nil {
+ return
+ }
+ }
+ _, err = ws.Bufrw.Write(payload)
+ if err != nil {
+ return
+ }
+
+ ws.Bufrw.Flush()
+
+ return
+}
+
+// Write a single message to the WebSocket stream. Destructively masks payload
+// in place if ws.IsClient. Messages are always sent as a single unfragmented
+// frame.
+func (ws *Websocket) WriteMessage(opcode byte, payload []byte) (err error) {
+ return ws.WriteFrame(opcode, payload)
+}
+
+// Split a string on commas and trim whitespace.
+func commaSplit(s string) []string {
+ var result []string
+ if strings.TrimSpace(s) == "" {
+ return result
+ }
+ for _, e := range strings.Split(s, ",") {
+ result = append(result, strings.TrimSpace(e))
+ }
+ return result
+}
+
+// Returns true iff one of the strings in haystack is needle.
+func containsCase(haystack []string, needle string) bool {
+ for _, e := range haystack {
+ if strings.ToLower(e) == strings.ToLower(needle) {
+ return true
+ }
+ }
+ return false
+}
+
+// One-step SHA-1 hash of a string.
+func sha1Hash(data string) []byte {
+ h := sha1.New()
+ h.Write([]byte(data))
+ return h.Sum(nil)
+}
+
+func httpError(w http.ResponseWriter, bufrw *bufio.ReadWriter, code int) {
+ w.Header().Set("Connection", "close")
+ bufrw.WriteString(fmt.Sprintf("HTTP/1.0 %d %s\r\n", code,
http.StatusText(code)))
+ w.Header().Write(bufrw)
+ bufrw.WriteString("\r\n")
+ bufrw.Flush()
+}
+
+// An implementation of http.Handler with a WebsocketConfig. The ServeHTTP
+// function calls websocketCallback assuming WebSocket HTTP negotiation is
+// successful.
+type WebSocketHTTPHandler struct {
+ Config *WebsocketConfig
+ WebsocketCallback func(*Websocket)
+}
+
+// Implements the http.Handler interface.
+func (handler *WebSocketHTTPHandler) ServeHTTP(w http.ResponseWriter, req
*http.Request) {
+ conn, bufrw, err := w.(http.Hijacker).Hijack()
+ if err != nil {
+ http.Error(w, err.Error(), http.StatusInternalServerError)
+ return
+ }
+ defer conn.Close()
+
+ // See RFC 6455 section 4.2.1 for this sequence of checks.
+
+ // 1. An HTTP/1.1 or higher GET request, including a "Request-URI"...
+ if req.Method != "GET" {
+ httpError(w, bufrw, http.StatusMethodNotAllowed)
+ return
+ }
+ if req.URL.Path != "/" {
+ httpError(w, bufrw, http.StatusNotFound)
+ return
+ }
+ // 2. A |Host| header field containing the server's authority.
+ // We deliberately skip this test.
+ // 3. An |Upgrade| header field containing the value "websocket",
+ // treated as an ASCII case-insensitive value.
+ if !containsCase(commaSplit(req.Header.Get("Upgrade")), "websocket") {
+ httpError(w, bufrw, http.StatusBadRequest)
+ return
+ }
+ // 4. A |Connection| header field that includes the token "Upgrade",
+ // treated as an ASCII case-insensitive value.
+ if !containsCase(commaSplit(req.Header.Get("Connection")), "Upgrade") {
+ httpError(w, bufrw, http.StatusBadRequest)
+ return
+ }
+ // 5. A |Sec-WebSocket-Key| header field with a base64-encoded value
+ // that, when decoded, is 16 bytes in length.
+ websocketKey := req.Header.Get("Sec-WebSocket-Key")
+ key, err := base64.StdEncoding.DecodeString(websocketKey)
+ if err != nil || len(key) != 16 {
+ httpError(w, bufrw, http.StatusBadRequest)
+ return
+ }
+ // 6. A |Sec-WebSocket-Version| header field, with a value of 13.
+ // We also allow 8 from draft-ietf-hybi-thewebsocketprotocol-10.
+ var knownVersions = []string{"8", "13"}
+ websocketVersion := req.Header.Get("Sec-WebSocket-Version")
+ if !containsCase(knownVersions, websocketVersion) {
+ // "If this version does not match a version understood by the
+ // server, the server MUST abort the WebSocket handshake
+ // described in this section and instead send an appropriate
+ // HTTP error code (such as 426 Upgrade Required) and a
+ // |Sec-WebSocket-Version| header field indicating the
+ // version(s) the server is capable of understanding."
+ w.Header().Set("Sec-WebSocket-Version",
strings.Join(knownVersions, ", "))
+ httpError(w, bufrw, 426)
+ return
+ }
+ // 7. Optionally, an |Origin| header field.
+ // 8. Optionally, a |Sec-WebSocket-Protocol| header field, with a list
of
+ // values indicating which protocols the client would like to speak,
ordered
+ // by preference.
+ clientProtocols := commaSplit(req.Header.Get("Sec-WebSocket-Protocol"))
+ // 9. Optionally, a |Sec-WebSocket-Extensions| header field...
+ // 10. Optionally, other header fields...
+
+ var ws Websocket
+ ws.Conn = conn
+ ws.Bufrw = bufrw
+ ws.IsClient = false
+ ws.MaxMessageSize = handler.Config.MaxMessageSize
+
+ // See RFC 6455 section 4.2.2, item 5 for these steps.
+
+ // 1. A Status-Line with a 101 response code as per RFC 2616.
+ bufrw.WriteString(fmt.Sprintf("HTTP/1.0 %d %s\r\n",
http.StatusSwitchingProtocols, http.StatusText(http.StatusSwitchingProtocols)))
+ // 2. An |Upgrade| header field with value "websocket" as per RFC 2616.
+ w.Header().Set("Upgrade", "websocket")
+ // 3. A |Connection| header field with value "Upgrade".
+ w.Header().Set("Connection", "Upgrade")
+ // 4. A |Sec-WebSocket-Accept| header field. The value of this header
+ // field is constructed by concatenating /key/, defined above in step 4
+ // in Section 4.2.2, with the string
+ // "258EAFA5-E914-47DA-95CA-C5AB0DC85B11", taking the SHA-1 hash of this
+ // concatenated value to obtain a 20-byte value and base64-encoding (see
+ // Section 4 of [RFC4648]) this 20-byte hash.
+ const magicGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
+ acceptKey := base64.StdEncoding.EncodeToString(sha1Hash(websocketKey +
magicGUID))
+ w.Header().Set("Sec-WebSocket-Accept", acceptKey)
+ // 5. Optionally, a |Sec-WebSocket-Protocol| header field, with a value
+ // /subprotocol/ as defined in step 4 in Section 4.2.2.
+ for _, clientProto := range clientProtocols {
+ for _, serverProto := range handler.Config.Subprotocols {
+ if clientProto == serverProto {
+ ws.Subprotocol = clientProto
+ w.Header().Set("Sec-WebSocket-Protocol",
clientProto)
+ break
+ }
+ }
+ }
+ // 6. Optionally, a |Sec-WebSocket-Extensions| header field...
+ w.Header().Write(bufrw)
+ bufrw.WriteString("\r\n")
+ bufrw.Flush()
+
+ // Call the WebSocket-specific handler.
+ handler.WebsocketCallback(&ws)
+}
+
+// Return an http.Handler with the given callback function.
+func (config *WebsocketConfig) Handler(callback func(*Websocket)) http.Handler
{
+ return &WebSocketHTTPHandler{config, callback}
+}
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