FS-11362 Attempt to rearrange verto socket shutdown sequence

src/mod/endpoints/mod_verto/ws.c

@@ -698,23 +698,6 @@ void ws_destroy(wsh_t *wsh)
 	}
 
 	if (wsh->ssl) {
-		int code, ssl_err, sanity = 100;
-		do {
-			code = SSL_shutdown(wsh->ssl);
-			if (code == 1) {
-				break;
-			}
-			if (code < 0) {
-				ssl_err = SSL_get_error(wsh->ssl, code);
-			}
-			if (wsh->block) {
-				ms_sleep(10);
-			} else {
-				ms_sleep(1);
-			}
-
-		} while ((code == 0 || (code < 0 && SSL_WANT_READ_WRITE(ssl_err))) && --sanity > 0);
-
 		SSL_free(wsh->ssl);
 		wsh->ssl = NULL;
 	}
@@ -749,12 +732,30 @@ ssize_t ws_close(wsh_t *wsh, int16_t reason)
 		ws_raw_write(wsh, fr, 4);
 	}
 
+	if (wsh->ssl && wsh->sock != ws_sock_invalid) {
+		/* first invocation of SSL_shutdown() would normally return 0 and just try to send SSL protocol close request.
+		   we just slightly polite, since we want to close socket fast and
+		   not bother waiting for SSL protocol close response before closing socket,
+		   since we want cleanup to be done fast for scenarios like:
+		   client change NAT (like jump from one WiFi to another) and now unreachable from old ip:port, however
+		   immidiately reconnect with new ip:port but old session id (and thus should replace the old session/channel)
+		*/
+		SSL_shutdown(wsh->ssl);
+	}
+
+	/* restore to blocking here, so any further read/writes will block */
 	restore_socket(wsh->sock);
 
 	if (wsh->close_sock && wsh->sock != ws_sock_invalid) {
+		/* signal socket to shutdown() before close(): FIN-ACK-FIN-ACK insead of RST-RST
+		   do not really handle errors here since it all going to die anyway.
+		   all buffered writes if any(like SSL_shutdown() ones) will still be sent.
+		 */
 #ifndef WIN32
+		shutdown(wsh->sock, SHUT_RDWR);
 		close(wsh->sock);
 #else
+		shutdown(wsh->sock, SD_BOTH);
 		closesocket(wsh->sock);
 #endif
 	}