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<?php
/**
* User: Marvin Borner
* Date: 14/09/2018
* Time: 23:48
*/
error_reporting(E_ERROR | E_PARSE);
include 'mysql_conf.inc';
$currentUrl = $argv[1];
while (true) {
crawl($currentUrl);
}
function crawl($url)
{
global $currentUrl;
if (!alreadyCrawled(cleanUrl($url))) {
$requestResponse = getContent($url);
if ($requestResponse[1] !== 404) {
print 'Download Size: ' . $requestResponse[2];
$htmlPath = createPathFromHtml($requestResponse[0]);
$urlInfo = getUrlInfo($htmlPath);
$allLinks = getLinks($htmlPath);
writeToQueue($allLinks);
saveData($urlInfo);
}
}
$currentUrl = getFirstFromQueue(); // set new
removeFromQueue($currentUrl);
}
function getContent($url)
{
$curl = curl_init($url);
curl_setopt($curl, CURLOPT_USERAGENT, 'Googlebot/2.1 (+http://www.google.com/bot.html)');
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_BINARYTRANSFER, true);
$content = curl_exec($curl);
$responseCode = curl_getinfo($curl, CURLINFO_HTTP_CODE);
$downloadSize = curl_getinfo($curl, CURLINFO_SIZE_DOWNLOAD) / 1000 . "KB\n";
curl_close($curl);
return [$content, $responseCode, $downloadSize];
}
function getUrlInfo($path)
{
$urlInfo = [];
$urlInfo['title'] = strip_tags($path->query('//title')[0]->textContent);
foreach ($path->query('//html') as $language) {
$urlInfo['language'] = strip_tags($language->getAttribute('lang'));
}
foreach ($path->query('/html/head/meta[@name="description"]') as $description) {
$urlInfo['description'] = strip_tags($description->getAttribute('content'));
}
// Fix empty information
if (!isset($urlInfo['description'])) {
$urlInfo['description'] = '';
foreach ($path->query('//p') as $text) {
if (strlen($urlInfo['description']) < 350) {
$urlInfo['description'] .= $text->textContent . ' ';
}
}
}
if (empty($urlInfo['title'])) {
$urlInfo['title'] = '';
if (strlen($urlInfo['title']) < 350) {
$urlInfo['title'] .= $path->query('//h1')[0]->textContent . ' ';
}
}
return $urlInfo;
}
function getLinks($path)
{
$allLinks = [];
foreach ($path->query('//a') as $ink) {
$href = cleanUrl($ink->getAttribute('href'));
$allLinks[] = $href;
}
return array_unique($allLinks);
}
function cleanUrl($url)
{
global $currentUrl;
$url = ltrim($url);
if (!(strpos($url, 'http') === 0)) {
if (strpos($url, 'www') === 0) {
$url = 'http://' . $url;
} else if (strpos($url, '/') === 0) {
$url = $currentUrl . $url;
} else {
$url = $currentUrl . $url;
}
}
// if it's pure domain without slash (prevents duplicate domains because of slash)
if (preg_match('/\w+\.\w{2,3}$/', $url)) {
$url .= '/';
}
// strip some things
$url = preg_replace('/([^:])(\/{2,})/', '$1/', $url); // double slashes
$url = strtok($url, '?'); // parameters
$url = strtok($url, '#'); // hash fragments
return $url;
}
function createPathFromHtml($content)
{
$dom = new DOMDocument();
libxml_use_internal_errors(true);
$dom->loadHTML($content);
libxml_use_internal_errors(false);
return new DOMXPath($dom);
}
function getFirstFromQueue()
{
$conn = initDbConnection();
$checkStmt = $conn->query('SELECT url FROM queue LIMIT 1');
return $checkStmt->fetchAll(PDO::FETCH_ASSOC)[0]['url'];
}
function writeToQueue($urls)
{
$conn = initDbConnection();
foreach ($urls as $url) {
$hash = md5($url);
$checkStmt = $conn->prepare('SELECT null FROM url_data where hash = :hash');
$checkStmt->execute(['hash' => $hash]);
if ($checkStmt->rowCount() === 0) {
$stmt = $conn->prepare('INSERT IGNORE INTO queue (url, hash) VALUES (:url, :hash)');
$stmt->execute([':url' => $url, 'hash' => $hash]);
}
}
}
function removeFromQueue($url)
{
$hash = md5($url);
$conn = initDbConnection();
$checkStmt = $conn->prepare('DELETE FROM queue where hash = :hash');
$checkStmt->execute(['hash' => $hash]);
}
function saveData($urlInfo)
{
global $currentUrl;
print $currentUrl . "\n";
$title = $urlInfo['title'] ?? '';
$description = $urlInfo['description'] ?? '';
$language = $urlInfo['language'] ?? 'en';
$hash = md5($currentUrl);
try {
$conn = initDbConnection();
$stmt = $conn->prepare('INSERT IGNORE INTO url_data (url, title, description, lang, hash) VALUES (:url, :title, :description, :lang, :hash)');
$stmt->execute([':url' => $currentUrl, ':title' => $title, ':description' => $description, ':lang' => $language, ':hash' => $hash]);
} catch (PDOException $e) {
print $e->getMessage();
}
}
function alreadyCrawled($url)
{
$hash = md5($url);
$conn = initDbConnection();
$checkStmt = $conn->prepare('SELECT null FROM url_data where hash = :hash');
$checkStmt->execute(['hash' => $hash]);
return $checkStmt->rowCount() !== 0; // return true if already crawled
}
function initDbConnection()
{
global $servername, $dbname, $username, $password;
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
return $conn;
}
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