cluster: fix inspector port assignment

Make sure that inspector ports in cluster are inside the valid range:
`[1024, 65535]`.
Fixes flaky `test-inspector-port-zero-cluster`.

PR-URL: https://github.com/nodejs/node/pull/18696
Fixes: https://github.com/nodejs/node/issues/18303
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/internal/cluster/master.js b/lib/internal/cluster/master.js
index 570cf7bc6f..3c6a398f11 100644
--- a/lib/internal/cluster/master.js
+++ b/lib/internal/cluster/master.js
@@ -14,6 +14,7 @@ const intercom = new EventEmitter();
 const SCHED_NONE = 1;
 const SCHED_RR = 2;
 const { isLegalPort } = require('internal/net');
+const [ minPort, maxPort ] = [ 1024, 65535 ];
 
 module.exports = cluster;
 
@@ -119,6 +120,8 @@ function createWorkerProcess(id, env) {
       }
     } else {
       inspectPort = process.debugPort + debugPortOffset;
+      if (inspectPort > maxPort)
+        inspectPort = inspectPort - maxPort + minPort - 1;
       debugPortOffset++;
     }