fix: Check if missed heartbeat synchronously before sending message

packages/engine.io-client/lib/socket.ts

@@ -10,6 +10,7 @@ import {
   CookieJar,
   createCookieJar,
   defaultBinaryType,
+  nextTick,
 } from "./globals.node.js";
 import debugModule from "debug"; // debug()
 
@@ -318,6 +319,8 @@ export class SocketWithoutUpgrade extends Emitter<
   private _pingTimeout: number = -1;
   private _maxPayload?: number = -1;
   private _pingTimeoutTimer: NodeJS.Timer;
+  private _pingTimeoutTime: number | null = null;
+  private _scheduledDisconnectFromIsResponsive = false;
   private clearTimeoutFn: typeof clearTimeout;
   private readonly _beforeunloadEventListener: () => void;
   private readonly _offlineEventListener: () => void;
@@ -628,9 +631,13 @@ export class SocketWithoutUpgrade extends Emitter<
    */
   private _resetPingTimeout() {
     this.clearTimeoutFn(this._pingTimeoutTimer);
+    if (this._pingInterval <= 0 || this._pingTimeout <= 0) return;
+
+    const delay = this._pingInterval + this._pingTimeout;
+    this._pingTimeoutTime = Date.now() + delay;
     this._pingTimeoutTimer = this.setTimeoutFn(() => {
       this._onClose("ping timeout");
-    }, this._pingInterval + this._pingTimeout);
+    }, delay);
     if (this.opts.autoUnref) {
       this._pingTimeoutTimer.unref();
     }
@@ -708,6 +715,32 @@ export class SocketWithoutUpgrade extends Emitter<
     return this.writeBuffer;
   }
 
+  /**
+   * Returns `true` if the connection is responding to heartbeats.
+   *
+   * If heartbeats are disabled this will always return `true`.
+   *
+   * @return {boolean}
+   */
+  public isResponsive() {
+    if (this.readyState === "closed") return false;
+    if (this._pingTimeoutTime === null) return true;
+
+    const responsive = Date.now() < this._pingTimeoutTime;
+    if (!responsive && !this._scheduledDisconnectFromIsResponsive) {
+      debug(
+        "`isResponsive` detected missed ping so scheduling connection close"
+      );
+      this._scheduledDisconnectFromIsResponsive = true;
+
+      nextTick(() => {
+        this._onClose("ping timeout");
+      }, this.setTimeoutFn);
+    }
+
+    return responsive;
+  }
+
   /**
    * Sends a message.
    *
@@ -717,6 +750,9 @@ export class SocketWithoutUpgrade extends Emitter<
    * @return {Socket} for chaining.
    */
   public write(msg: RawData, options?: WriteOptions, fn?: () => void) {
+    // this will schedule a disconnection on next tick if heartbeat missed
+    this.isResponsive();
+
     this._sendPacket("message", msg, options, fn);
     return this;
   }
@@ -730,8 +766,7 @@ export class SocketWithoutUpgrade extends Emitter<
    * @return {Socket} for chaining.
    */
   public send(msg: RawData, options?: WriteOptions, fn?: () => void) {
-    this._sendPacket("message", msg, options, fn);
-    return this;
+    return this.write(msg, options, fn);
   }
 
   /**
@@ -858,6 +893,7 @@ export class SocketWithoutUpgrade extends Emitter<
 
       // clear timers
       this.clearTimeoutFn(this._pingTimeoutTimer);
+      this._pingTimeoutTime = null;
 
       // stop event from firing again for transport
       this.transport.removeAllListeners("close");

packages/socket.io-client/lib/manager.ts

@@ -492,6 +492,17 @@ export class Manager<
     this._close();
   }
 
+  /**
+   * Returns `true` if the connection is responding to heartbeats.
+   *
+   * If heartbeats are disabled this will always return `true`.
+   *
+   * @return {boolean}
+   */
+  isResponsive() {
+    return this.engine.isResponsive ? this.engine.isResponsive() : true;
+  }
+
   /**
    * Writes a packet.
    *

packages/socket.io-client/lib/socket.ts

@@ -449,7 +449,10 @@ export class Socket<
       this.flags.volatile && (!isTransportWritable || !this.connected);
     if (discardPacket) {
       debug("discard packet as the transport is not currently writable");
-    } else if (this.connected) {
+    } else if (
+      this.connected &&
+      (this.flags.volatile || this.io.isResponsive())
+    ) {
       this.notifyOutgoingListeners(packet);
       this.packet(packet);
     } else {