CheckLength.php

<?php
/**
 * Check if the file is over given size.
 *
 * Use Content-Length header or partially download a file to see if it is bigger than specified size.
 * Downloads up to the $limit bytes but not more.
 *
 * Enjoy.
 */
class CheckLength
{
	private $downloaded;

	private $expected;

	private $limit = 1024;

	private $allowedTypes = array();

	private $contentType;


	private function handleProgress53($downloadExpected, $downloaded, $uploadExpected, $uploaded)
	{
		return $this->handleDownloadProgress($downloadExpected, $downloaded);
	}


	private function handleProgress55($curl, $downloadExpected, $downloaded, $uploadExpected, $uploaded)
	{
		return $this->handleDownloadProgress($downloadExpected, $downloaded);
	}


	private function handleDownloadProgress($downloadExpected, $downloaded)
	{
		if (isset($this->contentType) && !in_array($this->contentType, $this->allowedTypes)) {
			return 1;
		}

		$this->expected = $downloadExpected;
		if ($downloadExpected) {
			return 1;
		} else {
			$this->downloaded = $downloaded;
			if ($this->downloaded > $this->limit) {
				return 1;
			}
		}
	}


	private function handleHeader($curl, $header)
	{
		$header = strtolower($header);
		$line = explode(':', $header, 2);
		if (isset($line[1])) {
			if (trim($line[0]) === 'content-type') {
				$type = explode(';', $line[1], 2);
				$this->contentType = trim($type[0]);
			}
		}
		return strlen($header);
	}


	public function check($url)
	{
		$this->downloaded = 0;
		$this->contentType = null;
		$curl = curl_init();

		curl_setopt($curl, CURLOPT_URL, $url);
		curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
		curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
		curl_setopt($curl, CURLOPT_NOPROGRESS, 0);

		if (PHP_VERSION_ID >= 50500) {
			curl_setopt($curl, CURLOPT_PROGRESSFUNCTION, [$this, 'handleProgress55']);
		} elseif (PHP_VERSION_ID >= 50300) {
			curl_setopt($curl, CURLOPT_PROGRESSFUNCTION, [$this, 'handleProgress53']);
		} else {
			throw new \Exception('No support for CURLOPT_PROGRESSFUNCTION');
		}
		curl_setopt($curl, CURLOPT_HEADERFUNCTION, [$this, 'handleHeader']);
		curl_exec($curl);
	}


	public function setLimit($limit)
	{
		$this->limit = $limit;
	}


	public function setAllowedTypes($allowedTypes)
	{
		$this->allowedTypes = $allowedTypes;
	}


	public function getExpected()
	{
		return $this->expected;
	}


	public function getContentType()
	{
		return $this->contentType;
	}


	public function getDownloaded()
	{
		return $this->downloaded;
	}

}


$urls = array(
	'https://www.michalspacek.cz',  // a web page
	'http://cz1.php.net/get/php-5.6.5.tar.bz2/from/this/mirror',  // 10+ MB file download with Content-Length
	'http://test.localhost/test-10mb.php',  // 10+ MB file download without Content-Length
);

$limit = 1024 * 1024;
$types = array(
	'text/html',
	'foo/bar',
);

$c = new CheckLength();
$c->setLimit($limit);
$c->setAllowedTypes($types);

foreach ($urls as $url) {
	$c->check($url);
	$expected = $c->getExpected();
	$downloaded = $c->getDownloaded();
	$contentType = $c->getContentType();

	echo "URL: $url\n";
	echo "Content-Type: $contentType\n";
	if (!in_array($contentType, $types)) {
		echo "File not with allowed content type\n";
	}
	echo "File size: $expected\n";
	echo "Actually downloaded: $downloaded\n";
	if ($expected > $limit || $downloaded > $limit) {
		echo "File is bigger than $limit bytes\n";
	}
	echo "\n";
}