commit 07de40033e5caac513e03fa8956eeed6cede38cb
Author: David Fifield <[email protected]>
Date: Sun Nov 25 21:39:43 2012 -0800
WebSocket HTTP negotiation.
---
websocket-transport/websocket-server.go | 125 +++++++++++++++++++++++++++++++
1 files changed, 125 insertions(+), 0 deletions(-)
diff --git a/websocket-transport/websocket-server.go
b/websocket-transport/websocket-server.go
index d905364..c6effe4 100644
--- a/websocket-transport/websocket-server.go
+++ b/websocket-transport/websocket-server.go
@@ -1,11 +1,15 @@
package main
import (
+ "bufio"
+ "crypto/sha1"
+ "encoding/base64"
"fmt"
"net"
"net/http"
"os"
"os/signal"
+ "strings"
)
const defaultPort = 9901
@@ -18,7 +22,128 @@ func logDebug(format string, v ...interface{}) {
fmt.Fprintf(os.Stderr, format+"\n", v...)
}
+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()
+}
+
+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
+}
+
+func containsCase(haystack []string, needle string) bool {
+ for _, e := range haystack {
+ if strings.ToLower(e) == strings.ToLower(needle) {
+ return true
+ }
+ }
+ return false
+}
+
+func sha1Hash(data string) []byte {
+ h := sha1.New()
+ h.Write([]byte(data))
+ return h.Sum(nil)
+}
+
func handler(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.
+ _ = commaSplit(req.Header.Get("Sec-WebSocket-Protocol"))
+ // 9. Optionally, a |Sec-WebSocket-Extensions| header field...
+ // 10. Optionally, other header fields...
+
+ // 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.
+ // w.Header().Set("Sec-WebSocket-Protocol", "base64")
+ // 6. Optionally, a |Sec-WebSocket-Extensions| header field...
+ w.Header().Write(bufrw)
+ bufrw.WriteString("\r\n")
+ bufrw.Flush()
}
func startListener(addr *net.TCPAddr) (*net.TCPListener, error) {
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