<?php
/**
* This file is part of RSS-Bridge, a PHP project capable of generating RSS and
* Atom feeds for websites that don't have one.
*
* For the full license information, please view the UNLICENSE file distributed
* with this source code.
*
* @package Core
* @license http://unlicense.org/ UNLICENSE
* @link https://github.com/rss-bridge/rss-bridge
*/
function render(string $template, array $context = []): string
{
if ($template === 'base.html.php') {
throw new \Exception('Do not render base.html.php into itself');
}
$context['page'] = render_template($template, $context);
return render_template('base.html.php', $context);
}
/**
* Render template as absolute path or relative to templates folder.
* Do not pass user input in $template
*/
function render_template(string $template, array $context = []): string
{
if (isset($context['template'])) {
throw new \Exception("Don't use `template` as a context key");
}
$templateFilepath = __DIR__ . '/../templates/' . $template;
extract($context);
ob_start();
try {
if (is_file($template)) {
require $template;
} elseif (is_file($templateFilepath)) {
require $templateFilepath;
} else {
throw new \Exception(sprintf('Unable to find template `%s`', $template));
}
} catch (\Throwable $e) {
ob_end_clean();
throw $e;
}
return ob_get_clean();
}
/**
* Escape for html context
*/
function e(string $s): string
{
return htmlspecialchars($s, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
}
/**
* Explicitly don't escape
*/
function raw(string $s): string
{
return $s;
}
function truncate(string $s, int $length = 150, $marker = '...'): string
{
$s = trim($s);
if (mb_strlen($s) <= $length) {
return $s;
}
return mb_substr($s, 0, $length) . $marker;
}
/**
* Removes unwanted tags from a given HTML text.
*
* @param string $html The HTML text to sanitize.
* @param array $tags_to_remove A list of tags to remove from the DOM.
* @param array $attributes_to_keep A list of attributes to keep on tags (other
* attributes are removed).
* @param array $text_to_keep A list of tags where the innertext replaces the tag
* (i.e. `<p>Hello World!</p>` becomes `Hello World!`).
* @return object A simplehtmldom object of the remaining contents.
*
* @todo Check if this implementation is still necessary, because simplehtmldom
* already removes some of the tags (search for `remove_noise` in simple_html_dom.php).
*/
function sanitize(
$html,
$tags_to_remove = ['script', 'iframe', 'input', 'form'],
$attributes_to_keep = ['title', 'href', 'src'],
$text_to_keep = []
) {
$htmlContent = str_get_html($html);
foreach ($htmlContent->find('*') as $element) {
if (in_array($element->tag, $text_to_keep)) {
$element->outertext = $element->plaintext;
} elseif (in_array($element->tag, $tags_to_remove)) {
$element->outertext = '';
} else {
foreach ($element->getAllAttributes() as $attributeName => $attribute) {
if (!in_array($attributeName, $attributes_to_keep)) {
$element->removeAttribute($attributeName);
}
}
}
}
return $htmlContent;
}
function sanitize_html(string $html): string
{
$html = str_replace('<script', '<‌script', $html); // Disable scripts, but leave them visible.
$html = str_replace('<iframe', '<‌iframe', $html);
$html = str_replace('<link', '<‌link', $html);
// We leave alone object and embed so that videos can play in RSS readers.
return $html;
}
/**
* Replace background by image
*
* Replaces tags with styles of `backgroud-image` by `<img />` tags.
*
* For example:
*
* ```HTML
* <html>
* <body style="background-image: url('bgimage.jpg');">
* <h1>Hello world!</h1>
* </body>
* </html>
* ```
*
* results in this output:
*
* ```HTML
* <html>
* <img style="display:block;" src="bgimage.jpg" />
* </html>
* ```
*
* @param string $htmlContent The HTML content
* @return string The HTML content with all ocurrences replaced
*/
function backgroundToImg($htmlContent)
{
$regex = '/background-image[ ]{0,}:[ ]{0,}url\([\'"]{0,}(.*?)[\'"]{0,}\)/';
$htmlContent = str_get_html($htmlContent);
foreach ($htmlContent->find('*') as $element) {
if (preg_match($regex, $element->style, $matches) > 0) {
$element->outertext = '<img style="display:block;" src="' . $matches[1] . '" />';
}
}
return $htmlContent;
}
/**
* Convert relative links in HTML into absolute links
*
* This function is based on `php-urljoin`.
*
* @link https://github.com/plaidfluff/php-urljoin php-urljoin
*
* @param string|object $content The HTML content. Supports HTML objects or string objects
* @param string $server Fully qualified URL to the page containing relative links
* @return object Content with fixed URLs.
*/
function defaultLinkTo($content, $server)
{
$string_convert = false;
if (is_string($content)) {
$string_convert = true;
$content = str_get_html($content);
}
foreach ($content->find('img') as $image) {
$image->src = urljoin($server, $image->src);
}
foreach ($content->find('a') as $anchor) {
$anchor->href = urljoin($server, $anchor->href);
}
if ($string_convert) {
$content = $content->outertext;
}
return $content;
}
/**
* Extract the first part of a string matching the specified start and end delimiters
*
* @param string $string Input string, e.g. `<div>Post author: John Doe</div>`
* @param string $start Start delimiter, e.g. `author: `
* @param string $end End delimiter, e.g. `<`
* @return string|bool Extracted string, e.g. `John Doe`, or false if the
* delimiters were not found.
*/
function extractFromDelimiters($string, $start, $end)
{
if (strpos($string, $start) !== false) {
$section_retrieved = substr($string, strpos($string, $start) + strlen($start));
$section_retrieved = substr($section_retrieved, 0, strpos($section_retrieved, $end));
return $section_retrieved;
}
return false;
}
/**
* Remove one or more part(s) of a string using a start and end delmiters
*
* @param string $string Input string, e.g. `foo<script>superscript()</script>bar`
* @param string $start Start delimiter, e.g. `<script>`
* @param string $end End delimiter, e.g. `</script>`
* @return string Cleaned string, e.g. `foobar`
*/
function stripWithDelimiters($string, $start, $end)
{
while (strpos($string, $start) !== false) {
$section_to_remove = substr($string, strpos($string, $start));
$section_to_remove = substr($section_to_remove, 0, strpos($section_to_remove, $end) + strlen($end));
$string = str_replace($section_to_remove, '', $string);
}
return $string;
}
/**
* Remove HTML sections containing one or more sections using the same HTML tag
*
* @param string $string Input string, e.g. `foo<div class="ads"><div>ads</div>ads</div>bar`
* @param string $tag_name Name of the HTML tag, e.g. `div`
* @param string $tag_start Start of the HTML tag to remove, e.g. `<div class="ads">`
* @return string Cleaned String, e.g. `foobar`
*
* @todo This function needs more documentation to make it maintainable.
*/
function stripRecursiveHTMLSection($string, $tag_name, $tag_start)
{
$open_tag = '<' . $tag_name;
$close_tag = '</' . $tag_name . '>';
$close_tag_length = strlen($close_tag);
if (strpos($tag_start, $open_tag) === 0) {
while (strpos($string, $tag_start) !== false) {
$max_recursion = 100;
$section_to_remove = null;
$section_start = strpos($string, $tag_start);
$search_offset = $section_start;
do {
$max_recursion--;
$section_end = strpos($string, $close_tag, $search_offset);
$search_offset = $section_end + $close_tag_length;
$section_to_remove = substr($string, $section_start, $section_end - $section_start + $close_tag_length);
$open_tag_count = substr_count($section_to_remove, $open_tag);
$close_tag_count = substr_count($section_to_remove, $close_tag);
} while ($open_tag_count > $close_tag_count && $max_recursion > 0);
$string = str_replace($section_to_remove, '', $string);
}
}
return $string;
}
/**
* Convert Markdown into HTML with Parsedown.
*
* @link https://parsedown.org/ Parsedown
*
* @param string $string Input string in Markdown format
* @return string output string in HTML format
*/
function markdownToHtml($string)
{
$Parsedown = new Parsedown();
return $Parsedown->text($string);
}