Send OPTIONS request to the WebSockets interface once per Timeout interval. This allows some deployment environment to correctly detect the status of the application

application/controller/socket_verify.go

@@ -156,3 +156,8 @@ func (s socketVerification) Get(
 
 	return nil
 }
+
+func (s socketVerification) Options(
+	w http.ResponseWriter, r *http.Request, l log.Logger) error {
+	return nil
+}

ui/app.js

@@ -200,25 +200,29 @@ function startApp(rootEl) {
           await cipher.hmac512(enc.encode(finalKey), enc.encode(rTime))
         ).slice(0, 32);
       },
-      buildBackendSocketURL() {
-        let r = "";
+      buildBackendSocketURLs() {
+        let r = {
+          webSocket: "",
+          keepAlive: "",
+        };
 
         switch (location.protocol) {
           case "https:":
-            r = "wss://";
+            r.webSocket = "wss://";
             break;
 
           default:
-            r = "ws://";
+            r.webSocket = "ws://";
         }
 
-        r += location.host + socksInterface;
+        r.webSocket += location.host + socksInterface;
+        r.keepAlive = location.protocol + "//" + location.host + socksInterface;
 
         return r;
       },
       buildSocket(key, dialTimeout, heartbeatInterval) {
         return new Socket(
-          this.buildBackendSocketURL(),
+          this.buildBackendSocketURLs(),
           key,
           dialTimeout * 1000,
           heartbeatInterval * 1000

ui/socket.js

@@ -19,6 +19,7 @@ import * as crypt from "./crypto.js";
 import * as reader from "./stream/reader.js";
 import * as sender from "./stream/sender.js";
 import * as streams from "./stream/streams.js";
+import * as xhr from "./xhr.js";
 
 export const ECHO_FAILED = streams.ECHO_FAILED;
 
@@ -39,19 +40,22 @@ class Dial {
     this.address = address;
     this.timeout = timeout;
     this.privateKey = privateKey;
+    this.keepAliveTicker = null;
   }
 
   /**
    * Connect to the remote server
    *
+   * @param {string} address Target URL address
    * @param {number} timeout Connect timeout
    *
    * @returns {Promise<WebSocket>} When connection is established
    *
    */
-  connect(timeout) {
+  connect(address, timeout) {
+    const self = this;
     return new Promise((resolve, reject) => {
-      let ws = new WebSocket(this.address),
+      let ws = new WebSocket(address.webSocket),
         promised = false,
         timeoutTimer = setTimeout(() => {
           ws.close();
@@ -77,6 +81,12 @@ class Dial {
           return reject(e);
         };
 
+      if (!self.keepAliveTicker) {
+        self.keepAliveTicker = setInterval(() => {
+          xhr.options(address.keepAlive, {});
+        }, self.timeout);
+      }
+
       ws.addEventListener("open", (_event) => {
         myRes(ws);
       });
@@ -87,10 +97,14 @@ class Dial {
         };
 
         myRej(event);
+        clearInterval(self.keepAliveTicker);
+        self.keepAliveTicker = null;
       });
 
       ws.addEventListener("error", (_event) => {
         ws.close();
+        clearInterval(self.keepAliveTicker);
+        self.keepAliveTicker = null;
       });
     });
   }
@@ -123,7 +137,7 @@ class Dial {
    *
    */
   async dial(callbacks) {
-    let ws = await this.connect(this.timeout);
+    let ws = await this.connect(this.address, this.timeout);
 
     try {
       let rd = new reader.Reader(new reader.Multiple(() => {}), (data) => {

ui/xhr.js

@@ -15,7 +15,7 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-export function get(url, headers) {
+function send(method, url, headers) {
   return new Promise((res, rej) => {
     let authReq = new XMLHttpRequest();
 
@@ -35,7 +35,7 @@ export function get(url, headers) {
       rej(e);
     });
 
-    authReq.open("GET", url, true);
+    authReq.open(method, url, true);
 
     for (let h in headers) {
       authReq.setRequestHeader(h, headers[h]);
@@ -44,3 +44,11 @@ export function get(url, headers) {
     authReq.send();
   });
 }
+
+export function get(url, headers) {
+  return send("GET", url, headers);
+}
+
+export function options(url, headers) {
+  return send("OPTIONS", url, headers);
+}