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mirror of https://github.com/BookStackApp/BookStack.git synced 2024-11-24 03:42:32 +01:00
BookStack/app/Entities/Tools/PageContent.php
Dan Brown 85154fff69
Added an env configurable file upload size limit
Replaces the old suggestion of setting JS head 'window.uploadLimit'
variable. This new env option will be used by back-end validation and
front-end libs/logic too.

Limits already likely exist within prod environments at a PHP and
webserver level but this allows an app-level limit and centralises the
option on the BookStack side into the .env

Closes #3033
2021-11-14 22:03:22 +00:00

431 lines
14 KiB
PHP

<?php
namespace BookStack\Entities\Tools;
use BookStack\Entities\Models\Page;
use BookStack\Entities\Tools\Markdown\CustomListItemRenderer;
use BookStack\Entities\Tools\Markdown\CustomStrikeThroughExtension;
use BookStack\Exceptions\ImageUploadException;
use BookStack\Facades\Theme;
use BookStack\Theming\ThemeEvents;
use BookStack\Uploads\ImageRepo;
use BookStack\Uploads\ImageService;
use BookStack\Util\HtmlContentFilter;
use DOMDocument;
use DOMNodeList;
use DOMXPath;
use Illuminate\Support\Str;
use League\CommonMark\Block\Element\ListItem;
use League\CommonMark\CommonMarkConverter;
use League\CommonMark\Environment;
use League\CommonMark\Extension\Table\TableExtension;
use League\CommonMark\Extension\TaskList\TaskListExtension;
class PageContent
{
protected $page;
/**
* PageContent constructor.
*/
public function __construct(Page $page)
{
$this->page = $page;
}
/**
* Update the content of the page with new provided HTML.
*/
public function setNewHTML(string $html)
{
$html = $this->extractBase64ImagesFromHtml($html);
$this->page->html = $this->formatHtml($html);
$this->page->text = $this->toPlainText();
$this->page->markdown = '';
}
/**
* Update the content of the page with new provided Markdown content.
*/
public function setNewMarkdown(string $markdown)
{
$markdown = $this->extractBase64ImagesFromMarkdown($markdown);
$this->page->markdown = $markdown;
$html = $this->markdownToHtml($markdown);
$this->page->html = $this->formatHtml($html);
$this->page->text = $this->toPlainText();
}
/**
* Convert the given Markdown content to a HTML string.
*/
protected function markdownToHtml(string $markdown): string
{
$environment = Environment::createCommonMarkEnvironment();
$environment->addExtension(new TableExtension());
$environment->addExtension(new TaskListExtension());
$environment->addExtension(new CustomStrikeThroughExtension());
$environment = Theme::dispatch(ThemeEvents::COMMONMARK_ENVIRONMENT_CONFIGURE, $environment) ?? $environment;
$converter = new CommonMarkConverter([], $environment);
$environment->addBlockRenderer(ListItem::class, new CustomListItemRenderer(), 10);
return $converter->convertToHtml($markdown);
}
/**
* Convert all base64 image data to saved images.
*/
protected function extractBase64ImagesFromHtml(string $htmlText): string
{
if (empty($htmlText) || strpos($htmlText, 'data:image') === false) {
return $htmlText;
}
$doc = $this->loadDocumentFromHtml($htmlText);
$container = $doc->documentElement;
$body = $container->childNodes->item(0);
$childNodes = $body->childNodes;
$xPath = new DOMXPath($doc);
// Get all img elements with image data blobs
$imageNodes = $xPath->query('//img[contains(@src, \'data:image\')]');
foreach ($imageNodes as $imageNode) {
$imageSrc = $imageNode->getAttribute('src');
$newUrl = $this->base64ImageUriToUploadedImageUrl($imageSrc);
$imageNode->setAttribute('src', $newUrl);
}
// Generate inner html as a string
$html = '';
foreach ($childNodes as $childNode) {
$html .= $doc->saveHTML($childNode);
}
return $html;
}
/**
* Convert all inline base64 content to uploaded image files.
*/
protected function extractBase64ImagesFromMarkdown(string $markdown)
{
$matches = [];
preg_match_all('/!\[.*?]\(.*?(data:image\/.*?)[)"\s]/', $markdown, $matches);
foreach ($matches[1] as $base64Match) {
$newUrl = $this->base64ImageUriToUploadedImageUrl($base64Match);
$markdown = str_replace($base64Match, $newUrl, $markdown);
}
return $markdown;
}
/**
* Parse the given base64 image URI and return the URL to the created image instance.
* Returns an empty string if the parsed URI is invalid or causes an error upon upload.
*/
protected function base64ImageUriToUploadedImageUrl(string $uri): string
{
$imageRepo = app()->make(ImageRepo::class);
$imageInfo = $this->parseBase64ImageUri($uri);
// Validate extension and content
if (empty($imageInfo['data']) || !ImageService::isExtensionSupported($imageInfo['extension'])) {
return '';
}
// Validate that the content is not over our upload limit
$uploadLimitBytes = (config('app.upload_limit') * 1000000);
if (strlen($imageInfo['data']) > $uploadLimitBytes) {
return '';
}
// Save image from data with a random name
$imageName = 'embedded-image-' . Str::random(8) . '.' . $imageInfo['extension'];
try {
$image = $imageRepo->saveNewFromData($imageName, $imageInfo['data'], 'gallery', $this->page->id);
} catch (ImageUploadException $exception) {
return '';
}
return $image->url;
}
/**
* Parse a base64 image URI into the data and extension.
*
* @return array{extension: array, data: string}
*/
protected function parseBase64ImageUri(string $uri): array
{
[$dataDefinition, $base64ImageData] = explode(',', $uri, 2);
$extension = strtolower(preg_split('/[\/;]/', $dataDefinition)[1] ?? '');
return [
'extension' => $extension,
'data' => base64_decode($base64ImageData) ?: '',
];
}
/**
* Formats a page's html to be tagged correctly within the system.
*/
protected function formatHtml(string $htmlText): string
{
if (empty($htmlText)) {
return $htmlText;
}
$doc = $this->loadDocumentFromHtml($htmlText);
$container = $doc->documentElement;
$body = $container->childNodes->item(0);
$childNodes = $body->childNodes;
$xPath = new DOMXPath($doc);
// Set ids on top-level nodes
$idMap = [];
foreach ($childNodes as $index => $childNode) {
[$oldId, $newId] = $this->setUniqueId($childNode, $idMap);
if ($newId && $newId !== $oldId) {
$this->updateLinks($xPath, '#' . $oldId, '#' . $newId);
}
}
// Ensure no duplicate ids within child items
$idElems = $xPath->query('//body//*//*[@id]');
foreach ($idElems as $domElem) {
[$oldId, $newId] = $this->setUniqueId($domElem, $idMap);
if ($newId && $newId !== $oldId) {
$this->updateLinks($xPath, '#' . $oldId, '#' . $newId);
}
}
// Generate inner html as a string
$html = '';
foreach ($childNodes as $childNode) {
$html .= $doc->saveHTML($childNode);
}
return $html;
}
/**
* Update the all links to the $old location to instead point to $new.
*/
protected function updateLinks(DOMXPath $xpath, string $old, string $new)
{
$old = str_replace('"', '', $old);
$matchingLinks = $xpath->query('//body//*//*[@href="' . $old . '"]');
foreach ($matchingLinks as $domElem) {
$domElem->setAttribute('href', $new);
}
}
/**
* Set a unique id on the given DOMElement.
* A map for existing ID's should be passed in to check for current existence.
* Returns a pair of strings in the format [old_id, new_id].
*/
protected function setUniqueId(\DOMNode $element, array &$idMap): array
{
if (get_class($element) !== 'DOMElement') {
return ['', ''];
}
// Stop if there's an existing valid id that has not already been used.
$existingId = $element->getAttribute('id');
if (strpos($existingId, 'bkmrk') === 0 && !isset($idMap[$existingId])) {
$idMap[$existingId] = true;
return [$existingId, $existingId];
}
// Create an unique id for the element
// Uses the content as a basis to ensure output is the same every time
// the same content is passed through.
$contentId = 'bkmrk-' . mb_substr(strtolower(preg_replace('/\s+/', '-', trim($element->nodeValue))), 0, 20);
$newId = urlencode($contentId);
$loopIndex = 0;
while (isset($idMap[$newId])) {
$newId = urlencode($contentId . '-' . $loopIndex);
$loopIndex++;
}
$element->setAttribute('id', $newId);
$idMap[$newId] = true;
return [$existingId, $newId];
}
/**
* Get a plain-text visualisation of this page.
*/
protected function toPlainText(): string
{
$html = $this->render(true);
return html_entity_decode(strip_tags($html));
}
/**
* Render the page for viewing.
*/
public function render(bool $blankIncludes = false): string
{
$content = $this->page->html ?? '';
if (!config('app.allow_content_scripts')) {
$content = HtmlContentFilter::removeScripts($content);
}
if ($blankIncludes) {
$content = $this->blankPageIncludes($content);
} else {
$content = $this->parsePageIncludes($content);
}
return $content;
}
/**
* Parse the headers on the page to get a navigation menu.
*/
public function getNavigation(string $htmlContent): array
{
if (empty($htmlContent)) {
return [];
}
$doc = $this->loadDocumentFromHtml($htmlContent);
$xPath = new DOMXPath($doc);
$headers = $xPath->query('//h1|//h2|//h3|//h4|//h5|//h6');
return $headers ? $this->headerNodesToLevelList($headers) : [];
}
/**
* Convert a DOMNodeList into an array of readable header attributes
* with levels normalised to the lower header level.
*/
protected function headerNodesToLevelList(DOMNodeList $nodeList): array
{
$tree = collect($nodeList)->map(function ($header) {
$text = trim(str_replace("\xc2\xa0", '', $header->nodeValue));
$text = mb_substr($text, 0, 100);
return [
'nodeName' => strtolower($header->nodeName),
'level' => intval(str_replace('h', '', $header->nodeName)),
'link' => '#' . $header->getAttribute('id'),
'text' => $text,
];
})->filter(function ($header) {
return mb_strlen($header['text']) > 0;
});
// Shift headers if only smaller headers have been used
$levelChange = ($tree->pluck('level')->min() - 1);
$tree = $tree->map(function ($header) use ($levelChange) {
$header['level'] -= ($levelChange);
return $header;
});
return $tree->toArray();
}
/**
* Remove any page include tags within the given HTML.
*/
protected function blankPageIncludes(string $html): string
{
return preg_replace("/{{@\s?([0-9].*?)}}/", '', $html);
}
/**
* Parse any include tags "{{@<page_id>#section}}" to be part of the page.
*/
protected function parsePageIncludes(string $html): string
{
$matches = [];
preg_match_all("/{{@\s?([0-9].*?)}}/", $html, $matches);
foreach ($matches[1] as $index => $includeId) {
$fullMatch = $matches[0][$index];
$splitInclude = explode('#', $includeId, 2);
// Get page id from reference
$pageId = intval($splitInclude[0]);
if (is_nan($pageId)) {
continue;
}
// Find page and skip this if page not found
/** @var ?Page $matchedPage */
$matchedPage = Page::visible()->find($pageId);
if ($matchedPage === null) {
$html = str_replace($fullMatch, '', $html);
continue;
}
// If we only have page id, just insert all page html and continue.
if (count($splitInclude) === 1) {
$html = str_replace($fullMatch, $matchedPage->html, $html);
continue;
}
// Create and load HTML into a document
$innerContent = $this->fetchSectionOfPage($matchedPage, $splitInclude[1]);
$html = str_replace($fullMatch, trim($innerContent), $html);
}
return $html;
}
/**
* Fetch the content from a specific section of the given page.
*/
protected function fetchSectionOfPage(Page $page, string $sectionId): string
{
$topLevelTags = ['table', 'ul', 'ol'];
$doc = $this->loadDocumentFromHtml($page->html);
// Search included content for the id given and blank out if not exists.
$matchingElem = $doc->getElementById($sectionId);
if ($matchingElem === null) {
return '';
}
// Otherwise replace the content with the found content
// Checks if the top-level wrapper should be included by matching on tag types
$innerContent = '';
$isTopLevel = in_array(strtolower($matchingElem->nodeName), $topLevelTags);
if ($isTopLevel) {
$innerContent .= $doc->saveHTML($matchingElem);
} else {
foreach ($matchingElem->childNodes as $childNode) {
$innerContent .= $doc->saveHTML($childNode);
}
}
libxml_clear_errors();
return $innerContent;
}
/**
* Create and load a DOMDocument from the given html content.
*/
protected function loadDocumentFromHtml(string $html): DOMDocument
{
libxml_use_internal_errors(true);
$doc = new DOMDocument();
$html = '<body>' . $html . '</body>';
$doc->loadHTML(mb_convert_encoding($html, 'HTML-ENTITIES', 'UTF-8'));
return $doc;
}
}