Add BIMI plugin (roundcube#8143)

Brand Indicator Message Identification (BIMI) is an industry-wide standards effort to use brand logos as indicators to help email recipients recognize and avoid fraudulent messages.

See: https://datatracker.ietf.org/doc/draft-brand-indicators-for-message-identification/

Signed-off-by: Craig Andrews <[email protected]>

plugins/bimi/README.md

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+Roundcube Webmail BIMI Plugin
+=============================
+This plugin will use [Brand Indicators for Message Identification (BIMI)](https://bimigroup.org/) icons contact icons if a contact doesn't otherwise have an icon.
+
+Brand Indicator Message Identification (BIMI) is an industry-wide standards effort to use brand logos as indicators to help email recipients recognize and avoid fraudulent messages.
+
+[IETF: Brand Indicators for Message Identification (BIMI)](https://datatracker.ietf.org/doc/draft-brand-indicators-for-message-identification/)
+
+License
+=======
+This plugin is released under the GNU General Public License Version 3
+or later (http://www.gnu.org/licenses/gpl.html).
+
+Install
+=======
+* Place this plugin folder into plugins directory of Roundcube
+* Add bimi to $config['plugins'] in your Roundcube config
+
+Config
+======
+The default config file is plugins/bimi/config.inc.php.dist
+Rename this to plugins/bimi/config.inc.php
+

plugins/bimi/bimi.php

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+<?php
+
+/**
+ * BIMI
+ *
+ * Plugin to display Display Brand Indicators for Message Identification (BIMI) icons
+ * for contacts/addresses that do not have a photo image.
+ *
+ * @license GNU GPLv3+
+ * @author Craig Andrews <[email protected]>
+ * @website http://roundcube.net
+ */
+class bimi extends rcube_plugin
+{
+    public $task = 'addressbook';
+
+
+    /**
+     * Plugin initialization.
+     */
+    function init()
+    {
+        $this->add_hook('contact_photo', [$this, 'contact_photo']);
+    }
+
+    /**
+     * 'contact_photo' hook handler to inject a bimi image
+     */
+    function contact_photo($args)
+    {
+        // pre-conditions, exit if photo already exists or invalid input
+        if (!empty($args['url']) || !empty($args['data'])
+            || (empty($args['record']) && empty($args['email']))
+        ) {
+            return $args;
+        }
+
+        $rcmail = rcmail::get_instance();
+
+        // supporting edit/add action may be tricky, let's not do this
+        if ($rcmail->action == 'show' || $rcmail->action == 'photo') {
+            $email = !empty($args['email']) ? $args['email'] : null;
+
+            if (!$email && $args['record']) {
+                $addresses = rcube_addressbook::get_col_values('email', $args['record'], true);
+                if (!empty($addresses)) {
+                    $email = $addresses[0];
+                }
+            }
+
+            if ($email) {
+                require_once __DIR__ . '/bimi_engine.php';
+                $bimi_image = new bimi_engine($email);
+
+                if ($rcmail->action == 'show') {
+                    // set photo URL
+                    if (($icon = $bimi_image->getBinary()) && ($icon = base64_encode($icon))) {
+                        $mimetype = $bimi_image->getMimetype();
+                        $args['url'] = sprintf('data:%s;base64,%s', $mimetype, $icon);
+                    }
+                }
+                else {
+                    // send the icon to the browser
+                    if ($bimi_image->sendOutput()) {
+                        exit;
+                    }
+                }
+            }
+        }
+
+        return $args;
+    }
+}

plugins/bimi/bimi_engine.php

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+<?php
+
+/**
+ * @license GNU GPLv3+
+ * @author Craig Andrews <[email protected]>
+ */
+class bimi_engine
+{
+    private string $email;
+    private ?string $binary;
+
+    const MIME_TYPE = 'image/svg+xml';
+    const CACHE_NULL_VALUE = 'NOT FOUND';
+
+    /**
+     * Class constructor
+     *
+     * @param string $email   email address
+     */
+    public function __construct($email)
+    {
+        $this->email  = $email;
+        $this->retrieve();
+    }
+
+    /**
+     * Returns image mimetype
+     */
+    public function getMimetype()
+    {
+        return self::MIME_TYPE;
+    }
+
+    /**
+     * Returns the image in binary form
+     */
+    public function getBinary()
+    {
+        return $this->binary;
+    }
+
+    /**
+     * Sends the image to the browser
+     */
+    public function sendOutput()
+    {
+        if ($this->binary) {
+            $rcmail = rcmail::get_instance();
+            $rcmail->output->future_expire_header(10 * 60);
+
+            header('Content-Type: ' . self::MIME_TYPE);
+            header('Content-Size: ' . strlen($this->binary));
+            echo $this->binary;
+
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * BIMI retriever
+     */
+    private function retrieve()
+    {
+        if (preg_match('/.*@(.*)/', $this->email, $matches)) {
+            do {
+                $domain = $matches[1];
+                $this->binary = $this->cache_get_bimi_image($domain);
+                // If there's no BIMI at the subdomain, check the parent domain
+            }
+	    while($this->binary == null && preg_match('/.*?\.(.*)/', $domain, $matches));
+        }
+        else {
+            $this->binary = null;
+        }
+    }
+
+    /**
+     * Using the cache, given a domain, returns the BIMI image. The image is always SVG XML. Returns null if no image could be retrieved.
+     */
+    private function cache_get_bimi_image(string $domain): ?string
+    {
+        $rcmail = rcmail::get_instance();
+        $cache = $rcmail->get_cache_shared('bimi');
+        if ($cache && $cached_data=$cache->get($domain)) {
+            if ($cached_data==self::CACHE_NULL_VALUE) {
+                return null;
+            }
+            else {
+                return $cached_data;
+            }
+        }
+        else {
+            $data = $this->get_bimi_image($domain);
+            $cached_data=$data == null ? self::CACHE_NULL_VALUE : $data;
+            if ($cache) {
+                $cache->set($domain, $cached_data);
+            }
+            return $data;
+        }
+    }
+
+    /**
+     * Given a domain, returns the BIMI image. The image is always SVG XML. Returns null if no image could be retrieved.
+     */
+    private function get_bimi_image(string $domain): ?string
+    {
+        if ($bimi_url = $this->get_bimi_url($domain)) {
+            $rcmail = rcmail::get_instance();
+            $client = $rcmail->get_http_client();
+            $res = $client->request('GET', $bimi_url);
+            if ( $res->getStatusCode() == 200 && $res->hasHeader('Content-Type') && strcasecmp($res->getHeader('Content-Type')[0], self::MIME_TYPE) == 0) {
+                $svg = $res->getBody()->getContents();
+                $svg = rcmail_attachment_handler::svg_filter($svg);
+                return $svg;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Given a domain, returns the BIMI URL or null if there no such domain or the domain doesn't have a BIMI record.
+     */
+    private function get_bimi_url(string $domain): ?string
+    {
+        $bimi_record = dns_get_record("default._bimi.".$domain, DNS_TXT);
+        if ($bimi_record && sizeof($bimi_record) >= 1 && array_key_exists('txt', $bimi_record[0])) {
+            $bimi_record_value = $bimi_record[0]['txt'];
+            if (preg_match('@v=BIMI1(?:;|$)@i', $bimi_record_value, $svg) && preg_match('@l=(https://.+?)(?:;|$)@', $bimi_record_value, $matches)) {
+                $bimi_url = $matches[1];
+                return $bimi_url;
+            }
+        }
+        return null;
+    }
+}

plugins/bimi/config.inc.php.dist

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+<?php
+
+// Type of IMAP indexes cache. Supported values: 'db', 'apc' and 'memcache' or 'memcached'.
+$config['bimi_cache'] = 'db';