Add noreply shape check #36

Author: bwalkerl

classes/check/dnsnoreply.php

@@ -0,0 +1,93 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+/**
+ * DNS Email Noreply check.
+ *
+ * @package    tool_emailutils
+ * @author     Benjamin Walker <[email protected]>
+ * @copyright  Catalyst IT 2024
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ *
+ */
+
+namespace tool_emailutils\check;
+use core\check\check;
+use core\check\result;
+use tool_emailutils\dns_util;
+
+/**
+ * DNS Email Noreply check.
+ *
+ * @package    tool_emailutils
+ * @author     Benjamin Walker <[email protected]>
+ * @copyright  Catalyst IT 2024
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class dnsnoreply extends check {
+
+    /**
+     * A link to a place to action this
+     *
+     * @return \action_link|null
+     */
+    public function get_action_link(): ?\action_link {
+        return new \action_link(
+            new \moodle_url('/admin/settings.php?section=outgoingmailconfig'),
+            get_string('outgoingmailconfig', 'core_admin'));
+    }
+
+    /**
+     * Get Result.
+     *
+     * @return result
+     */
+    public function get_result() : result {
+        global $DB, $CFG;
+
+        $url = new \moodle_url($CFG->wwwroot);
+        $domain = $url->get_host();
+
+        $details = '';
+        $status = result::INFO;
+        $summary = '';
+
+        $dns = new dns_util();
+
+        $noreply = $dns->get_noreply();
+        $details .= "<p>No reply email: <code>$noreply</code></p>";
+
+        $noreplydomain = $dns->get_noreply_domain();
+        $details .= "<p>No reply domain: <code>$noreplydomain</code></p>";
+
+        $details .= "<p>LMS domain: <code>$domain</code></p>";
+
+        $primarydomain = $dns->get_primary_domain($domain);
+
+        if ($noreplydomain == $domain) {
+            $status = result::OK;
+            $summary = "LMS is same as noreply domain";
+        } else if (str_contains($domain, '.' . $noreplydomain)) {
+            $status = result::OK;
+            $summary = "LMS is a subdomain of noreply domain";
+        } else if (str_contains($noreplydomain, '.' . $primarydomain)) {
+            $summary = "LMS and noreply domain have a shared domain";
+        } else {
+            $summary = "LMS and noreply domain have nothing in common";
+        }
+
+        return new result($status, $summary, $details);
+    }
+}

classes/dns_util.php

@@ -58,6 +58,34 @@ public function get_noreply_domain() {
         return $noreplydomain;
     }
 
+    /**
+     * Attempts to extract the primary domain from a domain
+     *
+     * This may not always be clear, if there is any confusion return the full domain.
+     *
+     * @param string $domain
+     * @return string primary domain
+     */
+    public function get_primary_domain($domain) {
+        // This pattern works for the majority of cases, but can't be relied on for 100% accuracy.
+        // It can include subdomains if the main domain is 2 chars or less and there is no ccTLD.
+        $pattern = '/[a-z0-9][a-z0-9\-]{1,63}\.[a-z\.]{2,6}$/i';
+        return (preg_match($pattern, $domain, $matches) === 1) ? $matches[0] : $domain;
+    }
+
+    /**
+     * Attempts to extract the subdomains from a domain
+     *
+     * This may not always be clear, if there is any confusion return known subdomains or a blank string.
+     *
+     * @param string $domain
+     * @return string subdomains
+     */
+    public function get_subdomains($domain) {
+        $primarydomain = $this->get_primary_domain($domain);
+        return rtrim(strstr($domain, $primarydomain, true), '.');
+    }
+
     /**
      * Get spf txt record contents
      * @return string txt record

lang/en/tool_emailutils.php

@@ -47,6 +47,7 @@
 </ol>
 ';
 $string['checkdnsmx'] = 'DNS Email MX check';
+$string['checkdnsnoreply'] = 'DNS Email noreply shape check';
 $string['dnssettings'] = 'SPF / DKIM / DMARC DNS settings';
 $string['dnsspfinclude'] = 'SPF include';
 $string['dnsspfinclude_help'] = '<p>This is an SPF include domain which is expected to be present in the record. For example if this was set to <code>spf.acme.org</code> then the SPF security check would pass if the SPF record was <code>v=spf1 include:spf.acme.org -all</code>.</p>

lib.php

@@ -46,6 +46,7 @@ function tool_emailutils_security_checks() {
         new \tool_emailutils\check\dnsdkim(),
         new \tool_emailutils\check\dnsdmarc(),
         new \tool_emailutils\check\dnsmx(),
+        new \tool_emailutils\check\dnsnoreply(),
         new \tool_emailutils\check\dnspostmastertools(),
     ];
 }

version.php

@@ -25,8 +25,8 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version  = 2024011501;
-$plugin->release  = 2024011501;
+$plugin->version  = 2024011502;
+$plugin->release  = 2024011502;
 $plugin->requires = 2020061500;
 $plugin->component = 'tool_emailutils';
 $plugin->dependencies = [