In what scenarios should developers prioritize checking for specific content types or headers when verifying URLs in PHP applications?

Developers should prioritize checking for specific content types or headers when verifying URLs in PHP applications to ensure that the requested resource is of the expected type and format. This helps prevent security vulnerabilities such as content injection attacks or malicious file downloads. By validating content types and headers, developers can ensure that only safe and trusted resources are accessed by their application. 

$url = 'http://example.com/file.pdf';

$headers = get_headers($url);

$contentType = null;
foreach ($headers as $header) {
    if (strpos($header, 'Content-Type:') === 0) {
        $contentType = trim(substr($header, 13));
        break;
    }
}

if ($contentType !== 'application/pdf') {
    // Handle invalid content type
    die('Invalid content type');
}

// Process the PDF file
// ...

Keywords

PHP Content Types Headers URL Verification Security

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