From 4255496b113abf4ee989333510c62f5e3f2ddc37 Mon Sep 17 00:00:00 2001
From: Louis Lam <louislam@users.noreply.github.com>
Date: Fri, 24 Nov 2023 17:29:42 +0800
Subject: [PATCH] Rewrite Tailscale ping using spawnSync

---
 server/monitor-types/tailscale-ping.js | 41 +++++++++++---------------
 1 file changed, 18 insertions(+), 23 deletions(-)

diff --git a/server/monitor-types/tailscale-ping.js b/server/monitor-types/tailscale-ping.js
index eeec9e3f3..3b2ac487f 100644
--- a/server/monitor-types/tailscale-ping.js
+++ b/server/monitor-types/tailscale-ping.js
@@ -1,6 +1,6 @@
 const { MonitorType } = require("./monitor-type");
-const { UP, log } = require("../../src/util");
-const exec = require("child_process").exec;
+const { UP } = require("../../src/util");
+const childProcess = require("child_process");
 
 /**
  * A TailscalePing class extends the MonitorType.
@@ -23,7 +23,6 @@ class TailscalePing extends MonitorType {
             let tailscaleOutput = await this.runTailscalePing(monitor.hostname, monitor.interval);
             this.parseTailscaleOutput(tailscaleOutput, heartbeat);
         } catch (err) {
-            log.debug("Tailscale", err);
             // trigger log function somewhere to display a notification or alert to the user (but how?)
             throw new Error(`Error checking Tailscale ping: ${err}`);
         }
@@ -33,30 +32,26 @@ class TailscalePing extends MonitorType {
      * Runs the Tailscale ping command to the given URL.
      *
      * @param {string} hostname - The hostname to ping.
+     * @param {number} interval
      * @returns {Promise<string>} - A Promise that resolves to the output of the Tailscale ping command
      * @throws Will throw an error if the command execution encounters any error.
      */
     async runTailscalePing(hostname, interval) {
-        let cmd = `tailscale ping ${hostname}`;
-
-        log.debug("Tailscale", cmd);
-
-        return new Promise((resolve, reject) => {
-            let timeout = interval * 1000 * 0.8;
-            exec(cmd, { timeout: timeout }, (error, stdout, stderr) => {
-                // we may need to handle more cases if tailscale reports an error that isn't necessarily an error (such as not-logged in or DERP health-related issues)
-                if (error) {
-                    reject(`Execution error: ${error.message}`);
-                    return;
-                }
-                if (stderr) {
-                    reject(`Error in output: ${stderr}`);
-                    return;
-                }
-
-                resolve(stdout);
-            });
+        let timeout = interval * 1000 * 0.8;
+        let res = childProcess.spawnSync("tailscale", [ "ping", hostname ], {
+            timeout: timeout
         });
+        if (res.error) {
+            throw new Error(`Execution error: ${res.error.message}`);
+        }
+        if (res.stderr && res.stderr.toString()) {
+            throw new Error(`Error in output: ${res.stderr.toString()}`);
+        }
+        if (res.stdout && res.stdout.toString()) {
+            return res.stdout.toString();
+        } else {
+            throw new Error("No output from Tailscale ping");
+        }
     }
 
     /**
@@ -74,7 +69,7 @@ class TailscalePing extends MonitorType {
                 heartbeat.status = UP;
                 let time = line.split(" in ")[1].split(" ")[0];
                 heartbeat.ping = parseInt(time);
-                heartbeat.msg = line;
+                heartbeat.msg = "OK";
                 break;
             } else if (line.includes("timed out")) {
                 throw new Error(`Ping timed out: "${line}"`);