Flesh out Cobalt, LDAP groups, &c.

app/unit/LDAPServerUnit.js

@@ -1,6 +1,7 @@
 const Unit = require('libflitter/Unit')
 const LDAP = require('ldapjs')
 const Validator = require('email-validator')
+const net = require('net')
 
 // TODO support logging ALL ldap requests when in DEBUG, not just routed ones
 // TODO need to support LDAP server auto-discovery/detection features
@@ -89,11 +90,27 @@ class LDAPServerUnit extends Unit {
         }
 
         this.output.info(`Will listen on ${this.config.interface}:${this.config.port}`)
-        await new Promise((res, rej) => {
-            this.server.listen(this.config.port, this.config.interface, () => {
-                this.output.success(`LDAP server listening on port ${this.config.port}...`)
+        if ( await this.port_free() ) {
+            await new Promise((res, rej) => {
+                this.server.listen(this.config.port, this.config.interface, (err) => {
+                    this.output.success(`LDAP server listening on port ${this.config.port}...`)
+                    res()
+                })
+            })
+        } else {
+            this.output.error(`LDAP server port ${this.config.port} is not available. The LDAP server was not started.`)
+        }
+    }
+
+    async port_free() {
+        return new Promise((res, rej) => {
+            const server = net.createServer()
+            server.once('error', rej)
+            server.once('listening', () => {
+                server.close()
                 res()
             })
+            server.listen(this.config.port)
         })
     }