Add orphan inline images below the message body

* In plaintext mode: all inline images will be displayed below the message body
* In HTML mode: all inline images that are **not** referenced in the message HTML body will be listed below the message body

This doesn't add more CPU usage as it is using the already called HTML filtering function to discover if an inline part is referenced or not.

This fixes issue roundcube#5051 and is a bit better than roundcube#9150

program/actions/mail/index.php

@@ -896,10 +896,11 @@ public static function check_safe($message)
      * @param string $html         HTML
      * @param array  $p            Display parameters
      * @param array  $cid_replaces CID map replaces (inline images)
+     * @param array  $used_cids    List of CIDs appearing in message body
      *
      * @return string Clean HTML
      */
-    public static function wash_html($html, $p, $cid_replaces = [])
+    public static function wash_html($html, $p, $cid_replaces = [], &$used_cids = [])
     {
         $rcmail = rcmail::get_instance();
 
@@ -975,6 +976,7 @@ public static function wash_html($html, $p, $cid_replaces = [])
 
         $html = $washer->wash($html);
         self::$REMOTE_OBJECTS = $washer->extlinks;
+        $used_cids = $washer->get_used_cids();
 
         return $html;
     }
@@ -986,10 +988,11 @@ public static function wash_html($html, $p, $cid_replaces = [])
      * @param string             $body Message part body
      * @param rcube_message_part $part Message part
      * @param array              $p    Display parameters array
+     * @param array  $used_cids    List of CIDs appearing in message body
      *
      * @return string Formatted HTML string
      */
-    public static function print_body($body, $part, $p = [])
+    public static function print_body($body, $part, $p = [], &$used_cids = [])
     {
         $rcmail = rcmail::get_instance();
 
@@ -1006,6 +1009,8 @@ public static function print_body($body, $part, $p = [])
             ]
         );
 
+        $used_cids = [];
+
         // convert html to text/plain
         if ($data['plain'] && ($data['type'] == 'html' || $data['type'] == 'enriched')) {
             if ($data['type'] == 'enriched') {
@@ -1017,13 +1022,13 @@ public static function print_body($body, $part, $p = [])
         }
         // text/html
         elseif ($data['type'] == 'html') {
-            $body = self::wash_html($data['body'], $data, $part->replaces);
+            $body = self::wash_html($data['body'], $data, $part->replaces, $used_cids);
             $part->ctype_secondary = $data['type'];
         }
         // text/enriched
         elseif ($data['type'] == 'enriched') {
             $body = rcube_enriched::to_html($data['body']);
-            $body = self::wash_html($body, $data, $part->replaces);
+            $body = self::wash_html($body, $data, $part->replaces, $used_cids);
             $part->ctype_secondary = 'html';
         } else {
             // assert plaintext

program/actions/mail/show.php

@@ -649,6 +649,8 @@ public static function message_body($attrib)
             }
         }
 
+        $used_cids = [];
+
         if (!empty(self::$MESSAGE->parts)) {
             foreach (self::$MESSAGE->parts as $part) {
                 if ($part->type == 'headers') {
@@ -715,7 +717,7 @@ public static function message_body($attrib)
                     ];
 
                     // Parse the part content for display
-                    $body = self::print_body($body, $part, $body_args);
+                    $body = self::print_body($body, $part, $body_args, $used_cids);
 
                     // check if the message body is PGP encrypted
                     if (strpos($body, '-----BEGIN PGP MESSAGE-----') !== false) {
@@ -743,17 +745,21 @@ public static function message_body($attrib)
             }
         }
 
-        // list images after mail body
-        if ($rcmail->config->get('inline_images', true) && !empty(self::$MESSAGE->attachments)) {
+        // Fetch list of orphan inline parts
+        $orphan_parts = self::$MESSAGE->get_orphan_inline_parts($used_cids);
+        $attachments = array_merge(self::$MESSAGE->attachments, $orphan_parts);
+
+        // list images after mail body, if it's enabled or if message has orphan parts
+        if ((!empty($orphan_parts) || $rcmail->config->get('inline_images', true)) && !empty($attachments)) {
             $thumbnail_size   = $rcmail->config->get('image_thumbnail_size', 240);
             $show_label       = rcube::Q($rcmail->gettext('showattachment'));
             $download_label   = rcube::Q($rcmail->gettext('download'));
 
-            foreach (self::$MESSAGE->attachments as $attach_prop) {
+            foreach ($attachments as $attach_prop) {
                 // Content-Type: image/*...
                 if ($mimetype = self::part_image_type($attach_prop)) {
-                    // Skip inline images
-                    if (!self::is_attachment(self::$MESSAGE, $attach_prop)) {
+                    // Skip inline images, unless they are not in the body
+                    if (!self::is_attachment(self::$MESSAGE, $attach_prop) && !in_array($attach_prop, $orphan_parts)) {
                         continue;
                     }
 

program/lib/Roundcube/rcube_message.php

@@ -1030,6 +1030,38 @@ private function parse_structure($structure, $recursive = false)
         }
     }
 
+    /**
+     * Return list of orphan parts: inline images that are not included in the message HTML body
+     * @param  array $used_cids List of used CIDs in body
+     * @return array
+     */
+    public function get_orphan_inline_parts($used_cids)
+    {
+        $orphan_parts = [];
+
+        foreach ($this->inline_parts as $i => $part) {
+            $id = (string) $part->mime_id;
+
+            // The orphan part will not be returned if it is already in the attachments list
+            if (array_key_exists($id, $this->attachments)) {
+                continue;
+            }
+
+            if (isset($part->content_id)) {
+                $find = 'cid:' . $part->content_id;
+            }
+            elseif (!empty($part->content_location)) {
+                $find = $part->content_location;
+            }
+
+            if (!in_array($find, $used_cids)) {
+                $orphan_parts[$id] = $part;
+            }
+        }
+
+        return $orphan_parts;
+    }
+
     /**
      * Fill a flat array with references to all parts, indexed by part numbers
      *

program/lib/Roundcube/rcube_washtml.php

@@ -183,6 +183,9 @@ class rcube_washtml
     /** @var string A prefix to be added to id/class/for attribute values */
     private $_css_prefix;
 
+    /** @var array List of CIDs used in body */
+    private $_used_cids = [];
+
     /** @var int Max nesting level */
     private $max_nesting_level;
 
@@ -229,6 +232,16 @@ public function __construct($p = [])
         }
     }
 
+    /**
+     * Return list of CIDs that haven't been used in HTML
+     *
+     * @return array
+     */
+    public function get_used_cids()
+    {
+        return array_keys($this->_used_cids);
+    }
+
     /**
      * Register a callback function for a certain tag
      *
@@ -387,11 +400,13 @@ private function wash_attribs($node)
     private function wash_uri($uri, $blocked_source = false, $is_image = true)
     {
         if (!empty($this->config['cid_map'][$uri])) {
+            $this->_used_cids[$uri] = true;
             return $this->config['cid_map'][$uri];
         }
 
         $key = $this->config['base_url'] . $uri;
         if (!empty($this->config['cid_map'][$key])) {
+            $this->_used_cids[$key] = true;
             return $this->config['cid_map'][$key];
         }