From 7d34458553ca12c615af0de44a97e942c63854d9 Mon Sep 17 00:00:00 2001
From: Jan Prochazka <jan.prochazka@gmail.com>
Date: Mon, 3 May 2021 20:39:41 +0200
Subject: [PATCH] fixed race condition when using SSH tunnel #110

---
 packages/api/src/utility/sshTunnel.js | 61 +++++++++++++++------------
 1 file changed, 35 insertions(+), 26 deletions(-)

diff --git a/packages/api/src/utility/sshTunnel.js b/packages/api/src/utility/sshTunnel.js
index d30eced35..25484526a 100644
--- a/packages/api/src/utility/sshTunnel.js
+++ b/packages/api/src/utility/sshTunnel.js
@@ -4,6 +4,8 @@ const portfinder = require('portfinder');
 const stableStringify = require('json-stable-stringify');
 const _ = require('lodash');
 const platformInfo = require('./platformInfo');
+const AsyncLock = require('async-lock');
+const lock = new AsyncLock();
 
 const sshConnectionCache = {};
 const sshTunnelCache = {};
@@ -45,36 +47,43 @@ async function getSshConnection(connection) {
 }
 
 async function getSshTunnel(connection) {
-  const sshConn = await getSshConnection(connection);
   const tunnelCacheKey = stableStringify(_.pick(connection, TUNNEL_FIELDS));
-  if (sshTunnelCache[tunnelCacheKey]) return sshTunnelCache[tunnelCacheKey];
 
-  const localPort = await portfinder.getPortPromise({ port: 10000, stopPort: 60000 });
-  // workaround for `getPortPromise` not releasing the port quickly enough
-  await new Promise(resolve => setTimeout(resolve, 500));
-  const tunnelConfig = {
-    fromPort: localPort,
-    toPort: connection.port,
-    toHost: connection.server,
-  };
-  try {
-    const tunnel = await sshConn.forward(tunnelConfig);
-    console.log(
-      `Created SSH tunnel to ${connection.sshHost}-${connection.server}:${connection.port}, using local port ${localPort}`
-    );
+  return await lock.acquire(tunnelCacheKey, async () => {
+    const sshConn = await getSshConnection(connection);
+    if (sshTunnelCache[tunnelCacheKey]) return sshTunnelCache[tunnelCacheKey];
 
-    sshTunnelCache[tunnelCacheKey] = {
-      state: 'ok',
-      localPort,
+    const localPort = await portfinder.getPortPromise({ port: 10000, stopPort: 60000 });
+    // workaround for `getPortPromise` not releasing the port quickly enough
+    await new Promise(resolve => setTimeout(resolve, 500));
+    const tunnelConfig = {
+      fromPort: localPort,
+      toPort: connection.port,
+      toHost: connection.server,
     };
-    return sshTunnelCache[tunnelCacheKey];
-  } catch (err) {
-    // error is not cached
-    return {
-      state: 'error',
-      message: err.message,
-    };
-  }
+    try {
+      console.log(
+        `Creating SSH tunnel to ${connection.sshHost}-${connection.server}:${connection.port}, using local port ${localPort}`
+      );
+
+      const tunnel = await sshConn.forward(tunnelConfig);
+      console.log(
+        `Created SSH tunnel to ${connection.sshHost}-${connection.server}:${connection.port}, using local port ${localPort}`
+      );
+
+      sshTunnelCache[tunnelCacheKey] = {
+        state: 'ok',
+        localPort,
+      };
+      return sshTunnelCache[tunnelCacheKey];
+    } catch (err) {
+      // error is not cached
+      return {
+        state: 'error',
+        message: err.message,
+      };
+    }
+  });
 }
 
 module.exports = {