BookStack/app/Entities/Tools/PageContent.php

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<?php
namespace BookStack\Entities\Tools;
use BookStack\Entities\Models\Page;
use BookStack\Entities\Tools\Markdown\MarkdownToHtml;
use BookStack\Exceptions\ImageUploadException;
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use BookStack\Uploads\ImageRepo;
use BookStack\Uploads\ImageService;
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use BookStack\Util\HtmlContentFilter;
use DOMDocument;
use DOMElement;
use DOMNode;
use DOMNodeList;
use DOMXPath;
use Illuminate\Support\Str;
class PageContent
{
protected Page $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 = $this->toPlainText();
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$this->page->markdown = '';
}
/**
* Update the content of the page with new provided Markdown content.
*/
public function setNewMarkdown(string $markdown)
{
$markdown = $this->extractBase64ImagesFromMarkdown($markdown);
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$this->page->markdown = $markdown;
$html = (new MarkdownToHtml($markdown))->convert();
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$this->page->html = $this->formatHtml($html);
$this->page->text = $this->toPlainText();
}
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/**
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* Convert all base64 image data to saved images.
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*/
protected function extractBase64ImagesFromHtml(string $htmlText): string
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{
if (empty($htmlText) || strpos($htmlText, 'data:image') === false) {
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return $htmlText;
}
$doc = $this->loadDocumentFromHtml($htmlText);
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$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 $imageNode) {
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$imageSrc = $imageNode->getAttribute('src');
$newUrl = $this->base64ImageUriToUploadedImageUrl($imageSrc);
$imageNode->setAttribute('src', $newUrl);
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}
// 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.
* Regex is used to locate the start of data-uri definitions then
* manual looping over content is done to parse the whole data uri.
* Attempting to capture the whole data uri using regex can cause PHP
* PCRE limits to be hit with larger, multi-MB, files.
*/
protected function extractBase64ImagesFromMarkdown(string $markdown)
{
$matches = [];
$contentLength = strlen($markdown);
$replacements = [];
preg_match_all('/!\[.*?]\(.*?(data:image\/.{1,6};base64,)/', $markdown, $matches, PREG_OFFSET_CAPTURE);
foreach ($matches[1] as $base64MatchPair) {
[$dataUri, $index] = $base64MatchPair;
for ($i = strlen($dataUri) + $index; $i < $contentLength; $i++) {
$char = $markdown[$i];
if ($char === ')' || $char === ' ' || $char === "\n" || $char === '"') {
break;
}
$dataUri .= $char;
}
$newUrl = $this->base64ImageUriToUploadedImageUrl($dataUri);
$replacements[] = [$dataUri, $newUrl];
}
foreach ($replacements as [$dataUri, $newUrl]) {
$markdown = str_replace($dataUri, $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.
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*
* @return array{extension: string, data: string}
*/
protected function parseBase64ImageUri(string $uri): array
{
[$dataDefinition, $base64ImageData] = explode(',', $uri, 2);
$extension = strtolower(preg_split('/[\/;]/', $dataDefinition)[1] ?? '');
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return [
'extension' => $extension,
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'data' => base64_decode($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);
}
}
// Set ids on nested header nodes
$nestedHeaders = $xPath->query('//body//*//h1|//body//*//h2|//body//*//h3|//body//*//h4|//body//*//h5|//body//*//h6');
foreach ($nestedHeaders as $nestedHeader) {
[$oldId, $newId] = $this->setUniqueId($nestedHeader, $idMap);
if ($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);
}
// Perform required string-level tweaks
$html = str_replace(' ', '&nbsp;', $html);
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.
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* Returns a pair of strings in the format [old_id, new_id].
*/
protected function setUniqueId(DOMNode $element, array &$idMap): array
{
if (!$element instanceof 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;
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return [$existingId, $existingId];
}
// Create a 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;
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return [$existingId, $newId];
}
/**
* Get a plain-text visualisation of this page.
*/
protected function toPlainText(): string
{
$html = $this->render(true);
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return html_entity_decode(strip_tags($html));
}
/**
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* 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;
}
/**
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* 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);
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$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 (DOMElement $header) {
$text = trim(str_replace("\xc2\xa0", '', $header->nodeValue));
$text = mb_substr($text, 0, 100);
return [
'nodeName' => strtolower($header->nodeName),
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'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);
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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', 'pre'];
$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'));
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return $doc;
}
}