http: unbreak keepAliveTimeoutBuffer

Adds a guard.

Author: ronag

lib/_http_server.js

@@ -1027,11 +1027,16 @@ function resOnFinish(req, res, socket, state, server) {
       socket.end();
     }
   } else if (state.outgoing.length === 0) {
-    if (server.keepAliveTimeout && typeof socket.setTimeout === 'function') {
+    const keepAliveTimeout = NumberIsFinite(server.keepAliveTimeout) && server.keepAliveTimeout >= 0 ?
+      server.keepAliveTimeout : 0;
+    const keepAliveTimeoutBuffer = NumberIsFinite(server.keepAliveTimeoutBuffer) && server.keepAliveTimeoutBuffer >= 0 ?
+      server.keepAliveTimeoutBuffer : 1e3;
+
+    if (keepAliveTimeout && typeof socket.setTimeout === 'function') {
       // Extend the internal timeout by the configured buffer to reduce
       // the likelihood of ECONNRESET errors.
       // This allows fine-tuning beyond the advertised keepAliveTimeout.
-      socket.setTimeout(server.keepAliveTimeout + server.keepAliveTimeoutBuffer);
+      socket.setTimeout(keepAliveTimeout + keepAliveTimeoutBuffer);
       state.keepAliveTimeoutSet = true;
     }
   } else {