HTML Examples/WP.iso/wordpress/wp-includes/class-http.php

PHP Script | 2017-10-18 | 35.3 KB | 1,024 lines

<?php
/**
 * HTTP API: WP_Http class
 *
 * @package WordPress
 * @subpackage HTTP
 * @since 2.7.0
 */

if ( ! class_exists( 'Requests' ) ) {
    require( ABSPATH . WPINC . '/class-requests.php' );

    Requests::register_autoloader();
    Requests::set_certificate_path( ABSPATH . WPINC . '/certificates/ca-bundle.crt' );
}

/**
 * Core class used for managing HTTP transports and making HTTP requests.
 *
 * This class is used to consistently make outgoing HTTP requests easy for developers
 * while still being compatible with the many PHP configurations under which
 * WordPress runs.
 *
 * Debugging includes several actions, which pass different variables for debugging the HTTP API.
 *
 * @since 2.7.0
 */
class WP_Http {

    // Aliases for HTTP response codes.
    const HTTP_CONTINUE                   = 100;
    const SWITCHING_PROTOCOLS             = 101;
    const PROCESSING                      = 102;

    const OK                              = 200;
    const CREATED                         = 201;
    const ACCEPTED                        = 202;
    const NON_AUTHORITATIVE_INFORMATION   = 203;
    const NO_CONTENT                      = 204;
    const RESET_CONTENT                   = 205;
    const PARTIAL_CONTENT                 = 206;
    const MULTI_STATUS                    = 207;
    const IM_USED                         = 226;

    const MULTIPLE_CHOICES                = 300;
    const MOVED_PERMANENTLY               = 301;
    const FOUND                           = 302;
    const SEE_OTHER                       = 303;
    const NOT_MODIFIED                    = 304;
    const USE_PROXY                       = 305;
    const RESERVED                        = 306;
    const TEMPORARY_REDIRECT              = 307;
    const PERMANENT_REDIRECT              = 308;

    const BAD_REQUEST                     = 400;
    const UNAUTHORIZED                    = 401;
    const PAYMENT_REQUIRED                = 402;
    const FORBIDDEN                       = 403;
    const NOT_FOUND                       = 404;
    const METHOD_NOT_ALLOWED              = 405;
    const NOT_ACCEPTABLE                  = 406;
    const PROXY_AUTHENTICATION_REQUIRED   = 407;
    const REQUEST_TIMEOUT                 = 408;
    const CONFLICT                        = 409;
    const GONE                            = 410;
    const LENGTH_REQUIRED                 = 411;
    const PRECONDITION_FAILED             = 412;
    const REQUEST_ENTITY_TOO_LARGE        = 413;
    const REQUEST_URI_TOO_LONG            = 414;
    const UNSUPPORTED_MEDIA_TYPE          = 415;
    const REQUESTED_RANGE_NOT_SATISFIABLE = 416;
    const EXPECTATION_FAILED              = 417;
    const IM_A_TEAPOT                     = 418;
    const MISDIRECTED_REQUEST             = 421;
    const UNPROCESSABLE_ENTITY            = 422;
    const LOCKED                          = 423;
    const FAILED_DEPENDENCY               = 424;
    const UPGRADE_REQUIRED                = 426;
    const PRECONDITION_REQUIRED           = 428;
    const TOO_MANY_REQUESTS               = 429;
    const REQUEST_HEADER_FIELDS_TOO_LARGE = 431;
    const UNAVAILABLE_FOR_LEGAL_REASONS   = 451;

    const INTERNAL_SERVER_ERROR           = 500;
    const NOT_IMPLEMENTED                 = 501;
    const BAD_GATEWAY                     = 502;
    const SERVICE_UNAVAILABLE             = 503;
    const GATEWAY_TIMEOUT                 = 504;
    const HTTP_VERSION_NOT_SUPPORTED      = 505;
    const VARIANT_ALSO_NEGOTIATES         = 506;
    const INSUFFICIENT_STORAGE            = 507;
    const NOT_EXTENDED                    = 510;
    const NETWORK_AUTHENTICATION_REQUIRED = 511;

    /**
     * Send an HTTP request to a URI.
     *
     * Please note: The only URI that are supported in the HTTP Transport implementation
     * are the HTTP and HTTPS protocols.
     *
     * @since 2.7.0
     *
     * @param string       $url  The request URL.
     * @param string|array $args {
     *     Optional. Array or string of HTTP request arguments.
     *
     *     @type string       $method              Request method. Accepts 'GET', 'POST', 'HEAD', or 'PUT'.
     *                                             Some transports technically allow others, but should not be
     *                                             assumed. Default 'GET'.
     *     @type int          $timeout             How long the connection should stay open in seconds. Default 5.
     *     @type int          $redirection         Number of allowed redirects. Not supported by all transports
     *                                             Default 5.
     *     @type string       $httpversion         Version of the HTTP protocol to use. Accepts '1.0' and '1.1'.
     *                                             Default '1.0'.
     *     @type string       $user-agent          User-agent value sent.
     *                                             Default 'WordPress/' . get_bloginfo( 'version' ) . '; ' . get_bloginfo( 'url' ).
     *     @type bool         $reject_unsafe_urls  Whether to pass URLs through wp_http_validate_url().
     *                                             Default false.
     *     @type bool         $blocking            Whether the calling code requires the result of the request.
     *                                             If set to false, the request will be sent to the remote server,
     *                                             and processing returned to the calling code immediately, the caller
     *                                             will know if the request succeeded or failed, but will not receive
     *                                             any response from the remote server. Default true.
     *     @type string|array $headers             Array or string of headers to send with the request.
     *                                             Default empty array.
     *     @type array        $cookies             List of cookies to send with the request. Default empty array.
     *     @type string|array $body                Body to send with the request. Default null.
     *     @type bool         $compress            Whether to compress the $body when sending the request.
     *                                             Default false.
     *     @type bool         $decompress          Whether to decompress a compressed response. If set to false and
     *                                             compressed content is returned in the response anyway, it will
     *                                             need to be separately decompressed. Default true.
     *     @type bool         $sslverify           Whether to verify SSL for the request. Default true.
     *     @type string       sslcertificates      Absolute path to an SSL certificate .crt file.
     *                                             Default ABSPATH . WPINC . '/certificates/ca-bundle.crt'.
     *     @type bool         $stream              Whether to stream to a file. If set to true and no filename was
     *                                             given, it will be droped it in the WP temp dir and its name will
     *                                             be set using the basename of the URL. Default false.
     *     @type string       $filename            Filename of the file to write to when streaming. $stream must be
     *                                             set to true. Default null.
     *     @type int          $limit_response_size Size in bytes to limit the response to. Default null.
     *
     * }
     * @return array|WP_Error Array containing 'headers', 'body', 'response', 'cookies', 'filename'.
     *                        A WP_Error instance upon error.
     */
    public function request( $url, $args = array() ) {
        $defaults = array(
            'method' => 'GET',
            /**
             * Filters the timeout value for an HTTP request.
             *
             * @since 2.7.0
             *
             * @param int $timeout_value Time in seconds until a request times out.
             *                           Default 5.
             */
            'timeout' => apply_filters( 'http_request_timeout', 5 ),
            /**
             * Filters the number of redirects allowed during an HTTP request.
             *
             * @since 2.7.0
             *
             * @param int $redirect_count Number of redirects allowed. Default 5.
             */
            'redirection' => apply_filters( 'http_request_redirection_count', 5 ),
            /**
             * Filters the version of the HTTP protocol used in a request.
             *
             * @since 2.7.0
             *
             * @param string $version Version of HTTP used. Accepts '1.0' and '1.1'.
             *                        Default '1.0'.
             */
            'httpversion' => apply_filters( 'http_request_version', '1.0' ),
            /**
             * Filters the user agent value sent with an HTTP request.
             *
             * @since 2.7.0
             *
             * @param string $user_agent WordPress user agent string.
             */
            'user-agent' => apply_filters( 'http_headers_useragent', 'WordPress/' . get_bloginfo( 'version' ) . '; ' . get_bloginfo( 'url' ) ),
            /**
             * Filters whether to pass URLs through wp_http_validate_url() in an HTTP request.
             *
             * @since 3.6.0
             *
             * @param bool $pass_url Whether to pass URLs through wp_http_validate_url().
             *                       Default false.
             */
            'reject_unsafe_urls' => apply_filters( 'http_request_reject_unsafe_urls', false ),
            'blocking' => true,
            'headers' => array(),
            'cookies' => array(),
            'body' => null,
            'compress' => false,
            'decompress' => true,
            'sslverify' => true,
            'sslcertificates' => ABSPATH . WPINC . '/certificates/ca-bundle.crt',
            'stream' => false,
            'filename' => null,
            'limit_response_size' => null,
        );

        // Pre-parse for the HEAD checks.
        $args = wp_parse_args( $args );

        // By default, Head requests do not cause redirections.
        if ( isset($args['method']) && 'HEAD' == $args['method'] )
            $defaults['redirection'] = 0;

        $r = wp_parse_args( $args, $defaults );
        /**
         * Filters the arguments used in an HTTP request.
         *
         * @since 2.7.0
         *
         * @param array  $r   An array of HTTP request arguments.
         * @param string $url The request URL.
         */
        $r = apply_filters( 'http_request_args', $r, $url );

        // The transports decrement this, store a copy of the original value for loop purposes.
        if ( ! isset( $r['_redirection'] ) )
            $r['_redirection'] = $r['redirection'];

        /**
         * Filters whether to preempt an HTTP request's return value.
         *
         * Returning a non-false value from the filter will short-circuit the HTTP request and return
         * early with that value. A filter should return either:
         *
         *  - An array containing 'headers', 'body', 'response', 'cookies', and 'filename' elements
         *  - A WP_Error instance
         *  - boolean false (to avoid short-circuiting the response)
         *
         * Returning any other value may result in unexpected behaviour.
         *
         * @since 2.9.0
         *
         * @param false|array|WP_Error $preempt Whether to preempt an HTTP request's return value. Default false.
         * @param array               $r        HTTP request arguments.
         * @param string              $url      The request URL.
         */
        $pre = apply_filters( 'pre_http_request', false, $r, $url );

        if ( false !== $pre )
            return $pre;

        if ( function_exists( 'wp_kses_bad_protocol' ) ) {
            if ( $r['reject_unsafe_urls'] ) {
                $url = wp_http_validate_url( $url );
            }
            if ( $url ) {
                $url = wp_kses_bad_protocol( $url, array( 'http', 'https', 'ssl' ) );
            }
        }

        $arrURL = @parse_url( $url );

        if ( empty( $url ) || empty( $arrURL['scheme'] ) ) {
            return new WP_Error('http_request_failed', __('A valid URL was not provided.'));
        }

        if ( $this->block_request( $url ) ) {
            return new WP_Error( 'http_request_failed', __( 'User has blocked requests through HTTP.' ) );
        }

        // If we are streaming to a file but no filename was given drop it in the WP temp dir
        // and pick its name using the basename of the $url
        if ( $r['stream'] ) {
            if ( empty( $r['filename'] ) ) {
                $r['filename'] = get_temp_dir() . basename( $url );
            }

            // Force some settings if we are streaming to a file and check for existence and perms of destination directory
            $r['blocking'] = true;
            if ( ! wp_is_writable( dirname( $r['filename'] ) ) ) {
                return new WP_Error( 'http_request_failed', __( 'Destination directory for file streaming does not exist or is not writable.' ) );
            }
        }

        if ( is_null( $r['headers'] ) ) {
            $r['headers'] = array();
        }

        // WP allows passing in headers as a string, weirdly.
        if ( ! is_array( $r['headers'] ) ) {
            $processedHeaders = WP_Http::processHeaders( $r['headers'] );
            $r['headers'] = $processedHeaders['headers'];
        }

        // Setup arguments
        $headers = $r['headers'];
        $data = $r['body'];
        $type = $r['method'];
        $options = array(
            'timeout' => $r['timeout'],
            'useragent' => $r['user-agent'],
            'blocking' => $r['blocking'],
            'hooks' => new WP_HTTP_Requests_Hooks( $url, $r ),
        );

        // Ensure redirects follow browser behaviour.
        $options['hooks']->register( 'requests.before_redirect', array( get_class(), 'browser_redirect_compatibility' ) );

        // Validate redirected URLs.
        if ( function_exists( 'wp_kses_bad_protocol' ) && $r['reject_unsafe_urls'] ) {
            $options['hooks']->register( 'requests.before_redirect', array( get_class(), 'validate_redirects' ) );
        }

        if ( $r['stream'] ) {
            $options['filename'] = $r['filename'];
        }
        if ( empty( $r['redirection'] ) ) {
            $options['follow_redirects'] = false;
        } else {
            $options['redirects'] = $r['redirection'];
        }

        // Use byte limit, if we can
        if ( isset( $r['limit_response_size'] ) ) {
            $options['max_bytes'] = $r['limit_response_size'];
        }

        // If we've got cookies, use and convert them to Requests_Cookie.
        if ( ! empty( $r['cookies'] ) ) {
            $options['cookies'] = WP_Http::normalize_cookies( $r['cookies'] );
        }

        // SSL certificate handling
        if ( ! $r['sslverify'] ) {
            $options['verify'] = false;
            $options['verifyname'] = false;
        } else {
            $options['verify'] = $r['sslcertificates'];
        }

        // All non-GET/HEAD requests should put the arguments in the form body.
        if ( 'HEAD' !== $type && 'GET' !== $type ) {
            $options['data_format'] = 'body';
        }

        /**
         * Filters whether SSL should be verified for non-local requests.
         *
         * @since 2.8.0
         *
         * @param bool $ssl_verify Whether to verify the SSL connection. Default true.
         */
        $options['verify'] = apply_filters( 'https_ssl_verify', $options['verify'] );

        // Check for proxies.
        $proxy = new WP_HTTP_Proxy();
        if ( $proxy->is_enabled() && $proxy->send_through_proxy( $url ) ) {
            $options['proxy'] = new Requests_Proxy_HTTP( $proxy->host() . ':' . $proxy->port() );

            if ( $proxy->use_authentication() ) {
                $options['proxy']->use_authentication = true;
                $options['proxy']->user = $proxy->username();
                $options['proxy']->pass = $proxy->password();
            }
        }

        // Avoid issues where mbstring.func_overload is enabled
        mbstring_binary_safe_encoding();

        try {
            $requests_response = Requests::request( $url, $headers, $data, $type, $options );

            // Convert the response into an array
            $http_response = new WP_HTTP_Requests_Response( $requests_response, $r['filename'] );
            $response = $http_response->to_array();

            // Add the original object to the array.
            $response['http_response'] = $http_response;
        }
        catch ( Requests_Exception $e ) {
            $response = new WP_Error( 'http_request_failed', $e->getMessage() );
        }

        reset_mbstring_encoding();

        /**
         * Fires after an HTTP API response is received and before the response is returned.
         *
         * @since 2.8.0
         *
         * @param array|WP_Error $response HTTP response or WP_Error object.
         * @param string         $context  Context under which the hook is fired.
         * @param string         $class    HTTP transport used.
         * @param array          $r        HTTP request arguments.
         * @param string         $url      The request URL.
         */
        do_action( 'http_api_debug', $response, 'response', 'Requests', $r, $url );
        if ( is_wp_error( $response ) ) {
            return $response;
        }

        if ( ! $r['blocking'] ) {
            return array(
                'headers' => array(),
                'body' => '',
                'response' => array(
                    'code' => false,
                    'message' => false,
                ),
                'cookies' => array(),
                'http_response' => null,
            );
        }

        /**
         * Filters the HTTP API response immediately before the response is returned.
         *
         * @since 2.9.0
         *
         * @param array  $response HTTP response.
         * @param array  $r        HTTP request arguments.
         * @param string $url      The request URL.
         */
        return apply_filters( 'http_response', $response, $r, $url );
    }

    /**
     * Normalizes cookies for using in Requests.
     *
     * @since 4.6.0
     * @static
     *
     * @param array $cookies List of cookies to send with the request.
     * @return Requests_Cookie_Jar Cookie holder object.
     */
    public static function normalize_cookies( $cookies ) {
        $cookie_jar = new Requests_Cookie_Jar();

        foreach ( $cookies as $name => $value ) {
            if ( $value instanceof WP_Http_Cookie ) {
                $cookie_jar[ $value->name ] = new Requests_Cookie( $value->name, $value->value, $value->get_attributes() );
            } elseif ( is_scalar( $value ) ) {
                $cookie_jar[ $name ] = new Requests_Cookie( $name, $value );
            }
        }

        return $cookie_jar;
    }

    /**
     * Match redirect behaviour to browser handling.
     *
     * Changes 302 redirects from POST to GET to match browser handling. Per
     * RFC 7231, user agents can deviate from the strict reading of the
     * specification for compatibility purposes.
     *
     * @since 4.6.0
     * @static
     *
     * @param string            $location URL to redirect to.
     * @param array             $headers  Headers for the redirect.
     * @param string|array      $data     Body to send with the request.
     * @param array             $options  Redirect request options.
     * @param Requests_Response $original Response object.
     */
    public static function browser_redirect_compatibility( $location, $headers, $data, &$options, $original ) {
        // Browser compat
        if ( $original->status_code === 302 ) {
            $options['type'] = Requests::GET;
        }
    }

    /**
     * Validate redirected URLs.
     *
     * @since 4.7.5
     *
     * @throws Requests_Exception On unsuccessful URL validation
     * @param string $location URL to redirect to.
     */
    public static function validate_redirects( $location ) {
        if ( ! wp_http_validate_url( $location ) ) {
            throw new Requests_Exception( __('A valid URL was not provided.'), 'wp_http.redirect_failed_validation' );
        }
    }

    /**
     * Tests which transports are capable of supporting the request.
     *
     * @since 3.2.0
     *
     * @param array $args Request arguments
     * @param string $url URL to Request
     *
     * @return string|false Class name for the first transport that claims to support the request. False if no transport claims to support the request.
     */
    public function _get_first_available_transport( $args, $url = null ) {
        $transports = array( 'curl', 'streams' );

        /**
         * Filters which HTTP transports are available and in what order.
         *
         * @since 3.7.0
         *
         * @param array  $transports Array of HTTP transports to check. Default array contains
         *                           'curl', and 'streams', in that order.
         * @param array  $args       HTTP request arguments.
         * @param string $url        The URL to request.
         */
        $request_order = apply_filters( 'http_api_transports', $transports, $args, $url );

        // Loop over each transport on each HTTP request looking for one which will serve this request's needs.
        foreach ( $request_order as $transport ) {
            if ( in_array( $transport, $transports ) ) {
                $transport = ucfirst( $transport );
            }
            $class = 'WP_Http_' . $transport;

            // Check to see if this transport is a possibility, calls the transport statically.
            if ( !call_user_func( array( $class, 'test' ), $args, $url ) )
                continue;

            return $class;
        }

        return false;
    }

    /**
     * Dispatches a HTTP request to a supporting transport.
     *
     * Tests each transport in order to find a transport which matches the request arguments.
     * Also caches the transport instance to be used later.
     *
     * The order for requests is cURL, and then PHP Streams.
     *
     * @since 3.2.0
     *
     * @static
     *
     * @param string $url URL to Request
     * @param array $args Request arguments
     * @return array|WP_Error Array containing 'headers', 'body', 'response', 'cookies', 'filename'. A WP_Error instance upon error
     */
    private function _dispatch_request( $url, $args ) {
        static $transports = array();

        $class = $this->_get_first_available_transport( $args, $url );
        if ( !$class )
            return new WP_Error( 'http_failure', __( 'There are no HTTP transports available which can complete the requested request.' ) );

        // Transport claims to support request, instantiate it and give it a whirl.
        if ( empty( $transports[$class] ) )
            $transports[$class] = new $class;

        $response = $transports[$class]->request( $url, $args );

        /** This action is documented in wp-includes/class-http.php */
        do_action( 'http_api_debug', $response, 'response', $class, $args, $url );

        if ( is_wp_error( $response ) )
            return $response;

        /**
         * Filters the HTTP API response immediately before the response is returned.
         *
         * @since 2.9.0
         *
         * @param array  $response HTTP response.
         * @param array  $args     HTTP request arguments.
         * @param string $url      The request URL.
         */
        return apply_filters( 'http_response', $response, $args, $url );
    }

    /**
     * Uses the POST HTTP method.
     *
     * Used for sending data that is expected to be in the body.
     *
     * @since 2.7.0
     *
     * @param string       $url  The request URL.
     * @param string|array $args Optional. Override the defaults.
     * @return array|WP_Error Array containing 'headers', 'body', 'response', 'cookies', 'filename'. A WP_Error instance upon error
     */
    public function post($url, $args = array()) {
        $defaults = array('method' => 'POST');
        $r = wp_parse_args( $args, $defaults );
        return $this->request($url, $r);
    }

    /**
     * Uses the GET HTTP method.
     *
     * Used for sending data that is expected to be in the body.
     *
     * @since 2.7.0
     *
     * @param string $url The request URL.
     * @param string|array $args Optional. Override the defaults.
     * @return array|WP_Error Array containing 'headers', 'body', 'response', 'cookies', 'filename'. A WP_Error instance upon error
     */
    public function get($url, $args = array()) {
        $defaults = array('method' => 'GET');
        $r = wp_parse_args( $args, $defaults );
        return $this->request($url, $r);
    }

    /**
     * Uses the HEAD HTTP method.
     *
     * Used for sending data that is expected to be in the body.
     *
     * @since 2.7.0
     *
     * @param string $url The request URL.
     * @param string|array $args Optional. Override the defaults.
     * @return array|WP_Error Array containing 'headers', 'body', 'response', 'cookies', 'filename'. A WP_Error instance upon error
     */
    public function head($url, $args = array()) {
        $defaults = array('method' => 'HEAD');
        $r = wp_parse_args( $args, $defaults );
        return $this->request($url, $r);
    }

    /**
     * Parses the responses and splits the parts into headers and body.
     *
     * @static
     * @since 2.7.0
     *
     * @param string $strResponse The full response string
     * @return array Array with 'headers' and 'body' keys.
     */
    public static function processResponse($strResponse) {
        $res = explode("\r\n\r\n", $strResponse, 2);

        return array('headers' => $res[0], 'body' => isset($res[1]) ? $res[1] : '');
    }

    /**
     * Transform header string into an array.
     *
     * If an array is given then it is assumed to be raw header data with numeric keys with the
     * headers as the values. No headers must be passed that were already processed.
     *
     * @static
     * @since 2.7.0
     *
     * @param string|array $headers
     * @param string $url The URL that was requested
     * @return array Processed string headers. If duplicate headers are encountered,
     *                     Then a numbered array is returned as the value of that header-key.
     */
    public static function processHeaders( $headers, $url = '' ) {
        // Split headers, one per array element.
        if ( is_string($headers) ) {
            // Tolerate line terminator: CRLF = LF (RFC 2616 19.3).
            $headers = str_replace("\r\n", "\n", $headers);
            /*
             * Unfold folded header fields. LWS = [CRLF] 1*( SP | HT ) <US-ASCII SP, space (32)>,
             * <US-ASCII HT, horizontal-tab (9)> (RFC 2616 2.2).
             */
            $headers = preg_replace('/\n[ \t]/', ' ', $headers);
            // Create the headers array.
            $headers = explode("\n", $headers);
        }

        $response = array('code' => 0, 'message' => '');

        /*
         * If a redirection has taken place, The headers for each page request may have been passed.
         * In this case, determine the final HTTP header and parse from there.
         */
        for ( $i = count($headers)-1; $i >= 0; $i-- ) {
            if ( !empty($headers[$i]) && false === strpos($headers[$i], ':') ) {
                $headers = array_splice($headers, $i);
                break;
            }
        }

        $cookies = array();
        $newheaders = array();
        foreach ( (array) $headers as $tempheader ) {
            if ( empty($tempheader) )
                continue;

            if ( false === strpos($tempheader, ':') ) {
                $stack = explode(' ', $tempheader, 3);
                $stack[] = '';
                list( , $response['code'], $response['message']) = $stack;
                continue;
            }

            list($key, $value) = explode(':', $tempheader, 2);

            $key = strtolower( $key );
            $value = trim( $value );

            if ( isset( $newheaders[ $key ] ) ) {
                if ( ! is_array( $newheaders[ $key ] ) )
                    $newheaders[$key] = array( $newheaders[ $key ] );
                $newheaders[ $key ][] = $value;
            } else {
                $newheaders[ $key ] = $value;
            }
            if ( 'set-cookie' == $key )
                $cookies[] = new WP_Http_Cookie( $value, $url );
        }

        // Cast the Response Code to an int
        $response['code'] = intval( $response['code'] );

        return array('response' => $response, 'headers' => $newheaders, 'cookies' => $cookies);
    }

    /**
     * Takes the arguments for a ::request() and checks for the cookie array.
     *
     * If it's found, then it upgrades any basic name => value pairs to WP_Http_Cookie instances,
     * which are each parsed into strings and added to the Cookie: header (within the arguments array).
     * Edits the array by reference.
     *
     * @since 2.8.0
     * @static
     *
     * @param array $r Full array of args passed into ::request()
     */
    public static function buildCookieHeader( &$r ) {
        if ( ! empty($r['cookies']) ) {
            // Upgrade any name => value cookie pairs to WP_HTTP_Cookie instances.
            foreach ( $r['cookies'] as $name => $value ) {
                if ( ! is_object( $value ) )
                    $r['cookies'][ $name ] = new WP_Http_Cookie( array( 'name' => $name, 'value' => $value ) );
            }

            $cookies_header = '';
            foreach ( (array) $r['cookies'] as $cookie ) {
                $cookies_header .= $cookie->getHeaderValue() . '; ';
            }

            $cookies_header = substr( $cookies_header, 0, -2 );
            $r['headers']['cookie'] = $cookies_header;
        }
    }

    /**
     * Decodes chunk transfer-encoding, based off the HTTP 1.1 specification.
     *
     * Based off the HTTP http_encoding_dechunk function.
     *
     * @link https://tools.ietf.org/html/rfc2616#section-19.4.6 Process for chunked decoding.
     *
     * @since 2.7.0
     * @static
     *
     * @param string $body Body content
     * @return string Chunked decoded body on success or raw body on failure.
     */
    public static function chunkTransferDecode( $body ) {
        // The body is not chunked encoded or is malformed.
        if ( ! preg_match( '/^([0-9a-f]+)[^\r\n]*\r\n/i', trim( $body ) ) )
            return $body;

        $parsed_body = '';

        // We'll be altering $body, so need a backup in case of error.
        $body_original = $body;

        while ( true ) {
            $has_chunk = (bool) preg_match( '/^([0-9a-f]+)[^\r\n]*\r\n/i', $body, $match );
            if ( ! $has_chunk || empty( $match[1] ) )
                return $body_original;

            $length = hexdec( $match[1] );
            $chunk_length = strlen( $match[0] );

            // Parse out the chunk of data.
            $parsed_body .= substr( $body, $chunk_length, $length );

            // Remove the chunk from the raw data.
            $body = substr( $body, $length + $chunk_length );

            // End of the document.
            if ( '0' === trim( $body ) )
                return $parsed_body;
        }
    }

    /**
     * Block requests through the proxy.
     *
     * Those who are behind a proxy and want to prevent access to certain hosts may do so. This will
     * prevent plugins from working and core functionality, if you don't include api.wordpress.org.
     *
     * You block external URL requests by defining WP_HTTP_BLOCK_EXTERNAL as true in your wp-config.php
     * file and this will only allow localhost and your site to make requests. The constant
     * WP_ACCESSIBLE_HOSTS will allow additional hosts to go through for requests. The format of the
     * WP_ACCESSIBLE_HOSTS constant is a comma separated list of hostnames to allow, wildcard domains
     * are supported, eg *.wordpress.org will allow for all subdomains of wordpress.org to be contacted.
     *
     * @since 2.8.0
     * @link https://core.trac.wordpress.org/ticket/8927 Allow preventing external requests.
     * @link https://core.trac.wordpress.org/ticket/14636 Allow wildcard domains in WP_ACCESSIBLE_HOSTS
     *
     * @staticvar array|null $accessible_hosts
     * @staticvar array      $wildcard_regex
     *
     * @param string $uri URI of url.
     * @return bool True to block, false to allow.
     */
    public function block_request($uri) {
        // We don't need to block requests, because nothing is blocked.
        if ( ! defined( 'WP_HTTP_BLOCK_EXTERNAL' ) || ! WP_HTTP_BLOCK_EXTERNAL )
            return false;

        $check = parse_url($uri);
        if ( ! $check )
            return true;

        $home = parse_url( get_option('siteurl') );

        // Don't block requests back to ourselves by default.
        if ( 'localhost' == $check['host'] || ( isset( $home['host'] ) && $home['host'] == $check['host'] ) ) {
            /**
             * Filters whether to block local requests through the proxy.
             *
             * @since 2.8.0
             *
             * @param bool $block Whether to block local requests through proxy.
             *                    Default false.
             */
            return apply_filters( 'block_local_requests', false );
        }

        if ( !defined('WP_ACCESSIBLE_HOSTS') )
            return true;

        static $accessible_hosts = null;
        static $wildcard_regex = array();
        if ( null === $accessible_hosts ) {
            $accessible_hosts = preg_split('|,\s*|', WP_ACCESSIBLE_HOSTS);

            if ( false !== strpos(WP_ACCESSIBLE_HOSTS, '*') ) {
                $wildcard_regex = array();
                foreach ( $accessible_hosts as $host )
                    $wildcard_regex[] = str_replace( '\*', '.+', preg_quote( $host, '/' ) );
                $wildcard_regex = '/^(' . implode('|', $wildcard_regex) . ')$/i';
            }
        }

        if ( !empty($wildcard_regex) )
            return !preg_match($wildcard_regex, $check['host']);
        else
            return !in_array( $check['host'], $accessible_hosts ); //Inverse logic, If it's in the array, then we can't access it.

    }

    /**
     * Used as a wrapper for PHP's parse_url() function that handles edgecases in < PHP 5.4.7.
     *
     * @deprecated 4.4.0 Use wp_parse_url()
     * @see wp_parse_url()
     *
     * @param string $url The URL to parse.
     * @return bool|array False on failure; Array of URL components on success;
     *                    See parse_url()'s return values.
     */
    protected static function parse_url( $url ) {
        _deprecated_function( __METHOD__, '4.4.0', 'wp_parse_url()' );
        return wp_parse_url( $url );
    }

    /**
     * Converts a relative URL to an absolute URL relative to a given URL.
     *
     * If an Absolute URL is provided, no processing of that URL is done.
     *
     * @since 3.4.0
     *
     * @static
     *
     * @param string $maybe_relative_path The URL which might be relative
     * @param string $url                 The URL which $maybe_relative_path is relative to
     * @return string An Absolute URL, in a failure condition where the URL cannot be parsed, the relative URL will be returned.
     */
    public static function make_absolute_url( $maybe_relative_path, $url ) {
        if ( empty( $url ) )
            return $maybe_relative_path;

        if ( ! $url_parts = wp_parse_url( $url ) ) {
            return $maybe_relative_path;
        }

        if ( ! $relative_url_parts = wp_parse_url( $maybe_relative_path ) ) {
            return $maybe_relative_path;
        }

        // Check for a scheme on the 'relative' url
        if ( ! empty( $relative_url_parts['scheme'] ) ) {
            return $maybe_relative_path;
        }

        $absolute_path = $url_parts['scheme'] . '://';

        // Schemeless URL's will make it this far, so we check for a host in the relative url and convert it to a protocol-url
        if ( isset( $relative_url_parts['host'] ) ) {
            $absolute_path .= $relative_url_parts['host'];
            if ( isset( $relative_url_parts['port'] ) )
                $absolute_path .= ':' . $relative_url_parts['port'];
        } else {
            $absolute_path .= $url_parts['host'];
            if ( isset( $url_parts['port'] ) )
                $absolute_path .= ':' . $url_parts['port'];
        }

        // Start off with the Absolute URL path.
        $path = ! empty( $url_parts['path'] ) ? $url_parts['path'] : '/';

        // If it's a root-relative path, then great.
        if ( ! empty( $relative_url_parts['path'] ) && '/' == $relative_url_parts['path'][0] ) {
            $path = $relative_url_parts['path'];

        // Else it's a relative path.
        } elseif ( ! empty( $relative_url_parts['path'] ) ) {
            // Strip off any file components from the absolute path.
            $path = substr( $path, 0, strrpos( $path, '/' ) + 1 );

            // Build the new path.
            $path .= $relative_url_parts['path'];

            // Strip all /path/../ out of the path.
            while ( strpos( $path, '../' ) > 1 ) {
                $path = preg_replace( '![^/]+/\.\./!', '', $path );
            }

            // Strip any final leading ../ from the path.
            $path = preg_replace( '!^/(\.\./)+!', '', $path );
        }

        // Add the Query string.
        if ( ! empty( $relative_url_parts['query'] ) )
            $path .= '?' . $relative_url_parts['query'];

        return $absolute_path . '/' . ltrim( $path, '/' );
    }

    /**
     * Handles HTTP Redirects and follows them if appropriate.
     *
     * @since 3.7.0
     * @static
     *
     * @param string $url The URL which was requested.
     * @param array $args The Arguments which were used to make the request.
     * @param array $response The Response of the HTTP request.
     * @return false|object False if no redirect is present, a WP_HTTP or WP_Error result otherwise.
     */
    public static function handle_redirects( $url, $args, $response ) {
        // If no redirects are present, or, redirects were not requested, perform no action.
        if ( ! isset( $response['headers']['location'] ) || 0 === $args['_redirection'] )
            return false;

        // Only perform redirections on redirection http codes.
        if ( $response['response']['code'] > 399 || $response['response']['code'] < 300 )
            return false;

        // Don't redirect if we've run out of redirects.
        if ( $args['redirection']-- <= 0 )
            return new WP_Error( 'http_request_failed', __('Too many redirects.') );

        $redirect_location = $response['headers']['location'];

        // If there were multiple Location headers, use the last header specified.
        if ( is_array( $redirect_location ) )
            $redirect_location = array_pop( $redirect_location );

        $redirect_location = WP_Http::make_absolute_url( $redirect_location, $url );

        // POST requests should not POST to a redirected location.
        if ( 'POST' == $args['method'] ) {
            if ( in_array( $response['response']['code'], array( 302, 303 ) ) )
                $args['method'] = 'GET';
        }

        // Include valid cookies in the redirect process.
        if ( ! empty( $response['cookies'] ) ) {
            foreach ( $response['cookies'] as $cookie ) {
                if ( $cookie->test( $redirect_location ) )
                    $args['cookies'][] = $cookie;
            }
        }

        return wp_remote_request( $redirect_location, $args );
    }

    /**
     * Determines if a specified string represents an IP address or not.
     *
     * This function also detects the type of the IP address, returning either
     * '4' or '6' to represent a IPv4 and IPv6 address respectively.
     * This does not verify if the IP is a valid IP, only that it appears to be
     * an IP address.
     *
     * @link http://home.deds.nl/~aeron/regex/ for IPv6 regex
     *
     * @since 3.7.0
     * @static
     *
     * @param string $maybe_ip A suspected IP address
     * @return integer|bool Upon success, '4' or '6' to represent a IPv4 or IPv6 address, false upon failure
     */
    public static function is_ip_address( $maybe_ip ) {
        if ( preg_match( '/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/', $maybe_ip ) )
            return 4;

        if ( false !== strpos( $maybe_ip, ':' ) && preg_match( '/^(((?=.*(::))(?!.*\3.+\3))\3?|([\dA-F]{1,4}(\3|:\b|$)|\2))(?4){5}((?4){2}|(((2[0-4]|1\d|[1-9])?\d|25[0-5])\.?\b){4})$/i', trim( $maybe_ip, ' []' ) ) )
            return 6;

        return false;
    }

}