Move WebSocket API to it's own package and add websocket v4 endpoint (#5881)

utils/api.go

@@ -0,0 +1,24 @@
+// Copyright (c) 2017 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package utils
+
+import (
+	"net/http"
+	"strings"
+)
+
+type OriginCheckerProc func(*http.Request) bool
+
+func OriginChecker(r *http.Request) bool {
+	origin := r.Header.Get("Origin")
+	return *Cfg.ServiceSettings.AllowCorsFrom == "*" || strings.Contains(origin, *Cfg.ServiceSettings.AllowCorsFrom)
+}
+
+func GetOriginChecker(r *http.Request) OriginCheckerProc {
+	if len(*Cfg.ServiceSettings.AllowCorsFrom) > 0 {
+		return OriginChecker
+	}
+
+	return nil
+}