html: Balancing is important

9ae01bf2 turned off HTML balancing, however, quoted response removal will create unbalanced HTML. That HTML will be stored unbalanced and will require extra processing when displayed on the ticket thread. This patch adds balancing support using libxml if enabled, which will balance HTML without corrupting the HTML like htmLawed will with balancing enabled.

html: Balancing is important
9ae01bf2 turned off HTML balancing, however, quoted response removal will create unbalanced HTML. That HTML will be stored unbalanced and will require extra processing when displayed on the ticket thread. This patch adds balancing support using libxml if enabled, which will balance HTML without corrupting the HTML like htmLawed will with balancing enabled.
6c359046 · Jared Hancock · 56cc7098 · 6c359046
Commit 6c359046 authored 9 years ago by Jared Hancock
--- a/include/class.format.php
+++ b/include/class.format.php
@@ -115,11 +115,79 @@ class Format {
        return $len ? wordwrap($text, $len, "\n", true) : $text;
    }

-    function html($html, $config=array('balance'=>1)) {
+    function html_balance($html, $remove_empty=true) {
+        if (!extension_loaded('dom'))
+            return $html;
+
+        if (!trim($html))
+            return $html;
+
+        $doc = new DomDocument();
+        $xhtml = '<?xml encoding="utf-8"><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>'
+            // Wrap the content in a <div> because libxml would use a <p>
+            . "<div>$html</div>";
+        $doc->encoding = 'utf-8';
+        $doc->preserveWhitespace = false;
+        $doc->recover = true;
+        if (false === @$doc->loadHTML($xhtml))
+            return $html;
+
+        if ($remove_empty) {
+            // Remove empty nodes
+            $xpath = new DOMXPath($doc);
+            static $eE = array('area'=>1, 'br'=>1, 'col'=>1, 'embed'=>1,
+                'hr'=>1, 'img'=>1, 'input'=>1, 'isindex'=>1, 'param'=>1);
+            do {
+                $done = true;
+                $nodes = $xpath->query('//*[not(text()) and not(node())]');
+                foreach ($nodes as $n) {
+                    if (isset($eE[$n->nodeName]))
+                        continue;
+                    $n->parentNode->removeChild($n);
+                    $done = false;
+                }
+            } while (!$done);
+        }
+
+        static $phpversion;
+        if (!isset($phpversion))
+            $phpversion = phpversion();
+
+        $body = $doc->getElementsByTagName('body');
+        if (!$body->length)
+            return $html;
+
+        if ($phpversion > '5.3.6') {
+            $html = $doc->saveHTML($doc->getElementsByTagName('body')->item(0)->firstChild);
+        }
+        else {
+            $html = $doc->saveHTML();
+            $html = preg_replace('`^<!DOCTYPE.+?>|<\?xml .+?>|</?html>|</?body>|</?head>|<meta .+?/?>`', '', $html); # <?php
+        }
+        return preg_replace('`^<div>|</div>$`', '', $html);
+    }
+
+    function html($html, $config=array()) {
        require_once(INCLUDE_DIR.'htmLawed.php');
        $spec = false;
        if (isset($config['spec']))
            $spec = $config['spec'];
+
+        // Add in htmLawed defaults
+        $config += array(
+            'balance' => 1,
+        );
+
+        // Attempt to balance using libxml. htmLawed will corrupt HTML with
+        // balancing to fix improper HTML at the same time. For instance,
+        // some email clients may wrap block elements inside inline
+        // elements. htmLawed will change such block elements to inlines to
+        // make the HTML correct.
+        if ($config['balance'] && extension_loaded('dom')) {
+            $html = self::html_balance($html);
+            $config['balance'] = 0;
+        }
+
        return htmLawed($html, $config, $spec);
    }

@@ -200,7 +268,7 @@ class Format {
        }
    }

-    function safe_html($html) {
+    function safe_html($html, $balance=1) {
        // Remove HEAD and STYLE sections
        $html = preg_replace(
            array(':<(head|style|script).+?</\1>:is', # <head> and <style> sections
@@ -212,7 +280,7 @@ class Format {
            $html);
        $config = array(
            'safe' => 1, //Exclude applet, embed, iframe, object and script tags.
-            'balance' => 0, // No balance — corrupts poorly formatted Outlook html
+            'balance' => $balance,
            'comment' => 1, //Remove html comments (OUTLOOK LOVE THEM)
            'tidy' => -1,
            'deny_attribute' => 'id',
@@ -295,6 +363,7 @@ class Format {
            $text);

        //make urls clickable.
+        $text = self::html_balance($text, false);
        $text = Format::clickableurls($text);

        if ($inline_images)
@@ -366,6 +435,7 @@ class Format {
            },
            'schemes' => 'href: aim, feed, file, ftp, gopher, http, https, irc, mailto, news, nntp, sftp, ssh, telnet; *:file, http, https; src: cid, http, https, data',
            'elements' => '*+iframe',
+            'balance' => 0,
            'spec' => 'span=data-src,width,height',
        );
        return Format::html($text, $config);