WordPress URL Validation Function

url_validation.php

<?php

/**
 * Validate URLs
 * 
 * @param string $url
 * @param boolean $strict
 * @return string|boolean
 */
function kbso_validate_url( $url, $strict = false ) {
    
    // No URL to Validate
    if ( ! isset( $url ) || empty( $url ) ) {
        return false;
    }
    
    // Check for scheme e.g. http://
    $scheme = parse_url( $url, PHP_URL_SCHEME );
    
    // Add scheme if missing
    if ( empty( $scheme ) ) {
        $url = 'http://' . $url;
    }
    
    // Check for a valid URL
    if ( ! filter_var( $url, FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED ) ) {
        return false;
    }
    
    // If no strict check, return valid URL
    if ( true != $strict ) {
        return $url;
    }
    
    // Prepare HTTP Request Args
    $args = array(
        'timeout' => 5,
        'sslverify' => false,
    );
    
    $max_attempts = apply_filters( 'kbso_validate_url_attempts', 3 );
    
    $attempts = 0;
    
    $code = 0;
    
    while ( $attempts <= $max_attempts && 200 != $code ) {
        
        // Make GET HTTP Request
        $response = wp_remote_get( $url, $args );

        // Fetch the Response Code - Should be 200
        $code = wp_remote_retrieve_response_code( $response );
        
        $attempts++;
        
    }
    
    /*
     * Check the Response Code
     */
    if ( 200 == $code ) {
        
        return $url;
        
    } else {
        
        return false;
        
    }
    
}