Don't list images attached to multipart/related part as attachments (#7184)

3 files changed, 78 insertions, 9 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c37458644..bbfa89c2e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 - Update to jQuery-UI 1.13.1 (#8455)
 - Use navigator.pdfViewerEnabled for PDF viewer detection
 - Remove use of unreliable charset detection (#8344)
+- Don't list images attached to multipart/related part as attachments (#7184)
 - Password: Add support for ssha256 algorithm (#8459)
 - Fix slow loading of long HTML content into the HTML editor (#8108)
 - Fix bug where SMTP password didn't work if it contained '%p' (#8435)
diff --git a/program/actions/mail/index.php b/program/actions/mail/index.php
index c297bbba4..7447d5d05 100644
--- a/program/actions/mail/index.php
+++ b/program/actions/mail/index.php
@@ -1113,6 +1113,13 @@ class rcmail_action_mail_index extends rcmail_action
         return $out;
     }
 
+    /**
+     * Detect if a message attachment is an image (that can be displayed in the browser).
+     *
+     * @param rcube_message_part $part Message part - attachment
+     *
+     * @return string|null Image MIME type
+     */
     public static function part_image_type($part)
     {
         $mimetype = strtolower($part->mimetype);
diff --git a/program/actions/mail/show.php b/program/actions/mail/show.php
index b47f91e49..beedd78fd 100644
--- a/program/actions/mail/show.php
+++ b/program/actions/mail/show.php
@@ -176,6 +176,13 @@ class rcmail_action_mail_show extends rcmail_action_mail_index
         exit;
     }
 
+    /**
+     * Handler for the template object 'messageattachments'.
+     *
+     * @param array $attrib Named parameters
+     *
+     * @return string HTML content showing the message attachments list
+     */
     public static function message_attachments($attrib)
     {
         if (empty(self::$MESSAGE->attachments)) {
@@ -198,6 +205,11 @@ class rcmail_action_mail_show extends rcmail_action_mail_index
                 $mimetype = $type;
             }
 
+            // Skip inline images
+            if (strpos($mimetype, 'image/') === 0 && !self::is_attachment(self::$MESSAGE, $attach_prop)) {
+                continue;
+            }
+
             if (!empty($attrib['maxlength']) && mb_strlen($filename) > $attrib['maxlength']) {
                 $title    = $filename;
                 $filename = abbreviate_string($filename, $attrib['maxlength']);
@@ -329,6 +341,14 @@ class rcmail_action_mail_show extends rcmail_action_mail_index
         return html::div($attrib, $msg);
     }
 
+    /**
+     * Handler for the template object 'messageobjects' that contains
+     * warning/info boxes, buttons, etc. related to the displayed message.
+     *
+     * @param array $attrib Named parameters
+     *
+     * @return string HTML content showing the message objects
+     */
     public static function message_objects($attrib)
     {
         if (empty($attrib['id'])) {
@@ -350,6 +370,13 @@ class rcmail_action_mail_show extends rcmail_action_mail_index
         return html::div($attrib, $content);
     }
 
+    /**
+     * Handler for the template object 'contactphoto'.
+     *
+     * @param array $attrib Named parameters
+     *
+     * @return string HTML content for the IMG tag
+     */
     public static function message_contactphoto($attrib)
     {
         $rcmail        = rcmail::get_instance();
@@ -755,13 +782,13 @@ class rcmail_action_mail_show extends rcmail_action_mail_index
             $download_label   = rcube::Q($rcmail->gettext('download'));
 
             foreach (self::$MESSAGE->attachments as $attach_prop) {
-                // skip inline images
-                if (!empty($attach_prop->content_id) && $attach_prop->disposition == 'inline') {
-                    continue;
-                }
-
                 // Content-Type: image/*...
                 if ($mimetype = self::part_image_type($attach_prop)) {
+                    // Skip inline images
+                    if (!self::is_attachment(self::$MESSAGE, $attach_prop)) {
+                        continue;
+                    }
+
                     // display thumbnails
                     if ($thumbnail_size) {
                         $supported = in_array($mimetype, self::$CLIENT_MIMETYPES);
@@ -824,8 +851,13 @@ class rcmail_action_mail_show extends rcmail_action_mail_index
 
     /**
      * Returns a HTML notice element for too big message parts
+     *
+     * @param rcube_message $message Email message object
+     * @param string        $part_id Message part identifier
+     *
+     * @return string HTML content
      */
-    public static function part_too_big_message($MESSAGE, $part_id)
+    public static function part_too_big_message($message, $part_id)
     {
         $rcmail = rcmail::get_instance();
         $token  = $rcmail->get_request_token();
@@ -833,17 +865,20 @@ class rcmail_action_mail_show extends rcmail_action_mail_index
                 'task'     => 'mail',
                 'action'   => 'get',
                 'download' => 1,
-                'uid'      => $MESSAGE->uid,
+                'uid'      => $message->uid,
                 'part'     => $part_id,
-                'mbox'     => $MESSAGE->folder,
+                'mbox'     => $message->folder,
                 'token'    => $token,
         ]);
 
-        return html::span('part-notice', $rcmail->gettext('messagetoobig') . ' ' . html::a($url, $rcmail->gettext('download')));
+        return html::span('part-notice', $rcmail->gettext('messagetoobig')
+            . ' ' . html::a($url, $rcmail->gettext('download')));
     }
 
     /**
      * Handle disposition notification requests
+     *
+     * @param rcube_message $message Email message object
      */
     public static function mdn_request_handler($message)
     {
@@ -899,4 +934,30 @@ class rcmail_action_mail_show extends rcmail_action_mail_index
             }
         }
     }
+
+    /**
+     * Check whether the message part is a normal attachment
+     *
+     * @param rcube_message      $message Message object
+     * @param rcube_message_part $part    Message part
+     *
+     * @return bool
+     */
+    protected static function is_attachment($message, $part)
+    {
+        // Inline attachment with Content-Id specified
+        if (!empty($part->content_id) && $part->disposition == 'inline') {
+            return false;
+        }
+
+        // Any image attached to multipart/related message (#7184)
+        $parent_id = preg_replace('/\.[0-9]+$/', '', $part->mime_id);
+        $parent = $message->mime_parts[$parent_id] ?? null;
+
+        if ($parent && $parent->mimetype == 'multipart/related') {
+            return false;
+        }
+
+        return true;
+    }
 }