/ PHP 5.2.10 / cURL 7.19.4
			curl_setopt( $handle, CURLOPT_PROTOCOLS, CURLPROTO_HTTP | CURLPROTO_HTTPS );

		switch ( $r['method'] ) {
			case 'HEAD':
				curl_setopt( $handle, CURLOPT_NOBODY, true );
				break;
			case 'POST':
				curl_setopt( $handle, CURLOPT_POST, true );
				curl_setopt( $handle, CURLOPT_POSTFIELDS, $r['body'] );
				break;
			case 'PUT':
				curl_setopt( $handle, CURLOPT_CUSTOMREQUEST, 'PUT' );
				curl_setopt( $handle, CURLOPT_POSTFIELDS, $r['body'] );
				break;
			default:
				curl_setopt( $handle, CURLOPT_CUSTOMREQUEST, $r['method'] );
				if ( ! is_null( $r['body'] ) )
					curl_setopt( $handle, CURLOPT_POSTFIELDS, $r['body'] );
				break;
		}

		if ( true === $r['blocking'] ) {
			curl_setopt( $handle, CURLOPT_HEADERFUNCTION, array( $this, 'stream_headers' ) );
			curl_setopt( $handle, CURLOPT_WRITEFUNCTION, array( $this, 'stream_body' ) );
		}

		curl_setopt( $handle, CURLOPT_HEADER, false );

		if ( isset( $r['limit_response_size'] ) )
			$this->max_body_length = intval( $r['limit_response_size'] );
		else
			$this->max_body_length = false;

		// If streaming to a file open a file handle, and setup our curl streaming handler.
		if ( $r['stream'] ) {
			if ( ! WP_DEBUG )
				$this->stream_handle = @fopen( $r['filename'], 'w+' );
			else
				$this->stream_handle = fopen( $r['filename'], 'w+' );
			if ( ! $this->stream_handle )
				return new WP_Error( 'http_request_failed', sprintf( __( 'Could not open handle for fopen() to %s' ), $r['filename'] ) );
		} else {
			$this->stream_handle = false;
		}

		if ( !empty( $r['headers'] ) ) {
			// cURL expects full header strings in each element.
			$headers = array();
			foreach ( $r['headers'] as $name => $value ) {
				$headers[] = "{$name}: $value";
			}
			curl_setopt( $handle, CURLOPT_HTTPHEADER, $headers );
		}

		if ( $r['httpversion'] == '1.0' )
			curl_setopt( $handle, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_0 );
		else
			curl_setopt( $handle, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1 );

		/**
		 * Fires before the cURL request is executed.
		 *
		 * Cookies are not currently handled by the HTTP API. This action allows
		 * plugins to handle cookies themselves.
		 *
		 * @since 2.8.0
		 *
		 * @param resource &$handle The cURL handle returned by curl_init().
		 * @param array    $r       The HTTP request arguments.
		 * @param string   $url     The request URL.
		 */
		do_action_ref_array( 'http_api_curl', array( &$handle, $r, $url ) );

		// We don't need to return the body, so don't. Just execute request and return.
		if ( ! $r['blocking'] ) {
			curl_exec( $handle );

			if ( $curl_error = curl_error( $handle ) ) {
				curl_close( $handle );
				return new WP_Error( 'http_request_failed', $curl_error );
			}
			if ( in_array( curl_getinfo( $handle, CURLINFO_HTTP_CODE ), array( 301, 302 ) ) ) {
				curl_close( $handle );
				return new WP_Error( 'http_request_failed', __( 'Too many redirects.' ) );
			}

			curl_close( $handle );
			return array( 'headers' => array(), 'body' => '', 'response' => array('code' => false, 'message' => false), 'cookies' => array() );
		}

		curl_exec( $handle );
		$theHeaders = WP_Http::processHeaders( $this->headers, $url );
		$theBody = $this->body;
		$bytes_written_total = $this->bytes_written_total;

		$this->headers = '';
		$this->body = '';
		$this->bytes_written_total = 0;

		$curl_error = curl_errno( $handle );

		// If an error occurred, or, no response.
		if ( $curl_error || ( 0 == strlen( $theBody ) && empty( $theHeaders['headers'] ) ) ) {
			if ( CURLE_WRITE_ERROR /* 23 */ == $curl_error ) {
				if ( ! $this->max_body_length || $this->max_body_length != $bytes_written_total ) {
					if ( $r['stream'] ) {
						curl_close( $handle );
						fclose( $this->stream_handle );
						return new WP_Error( 'http_request_failed', __( 'Failed to write request to temporary file.' ) );
					} else {
						curl_close( $handle );
						return new WP_Error( 'http_request_failed', curl_error( $handle ) );
					}
				}
			} else {
				if ( $curl_error = curl_error( $handle ) ) {
					curl_close( $handle );
					return new WP_Error( 'http_request_failed', $curl_error );
				}
			}
			if ( in_array( curl_getinfo( $handle, CURLINFO_HTTP_CODE ), array( 301, 302 ) ) ) {
				curl_close( $handle );
				return new WP_Error( 'http_request_failed', __( 'Too many redirects.' ) );
			}
		}

		curl_close( $handle );

		if ( $r['stream'] )
			fclose( $this->stream_handle );

		$response = array(
			'headers' => $theHeaders['headers'],
			'body' => null,
			'response' => $theHeaders['response'],
			'cookies' => $theHeaders['cookies'],
			'filename' => $r['filename']
		);

		// Handle redirects.
		if ( false !== ( $redirect_response = WP_HTTP::handle_redirects( $url, $r, $response ) ) )
			return $redirect_response;

		if ( true === $r['decompress'] && true === WP_Http_Encoding::should_decode($theHeaders['headers']) )
			$theBody = WP_Http_Encoding::decompress( $theBody );

		$response['body'] = $theBody;

		return $response;
	}

	/**
	 * Grabs the headers of the cURL request.
	 *
	 * Each header is sent individually to this callback, so we append to the `$header` property
	 * for temporary storage
	 *
	 * @since 3.2.0
	 * @access private
	 *
	 * @param resource $handle  cURL handle.
	 * @param string   $headers cURL request headers.
	 * @return int Length of the request headers.
	 */
	private function stream_headers( $handle, $headers ) {
		$this->headers .= $headers;
		return strlen( $headers );
	}

	/**
	 * Grabs the body of the cURL request.
	 *
	 * The contents of the document are passed in chunks, so we append to the `$body`
	 * property for temporary storage. Returning a length shorter than the length of
	 * `$data` passed in will cause cURL to abort the request with `CURLE_WRITE_ERROR`.
	 *
	 * @since 3.6.0
	 * @access private
	 *
	 * @param resource $handle  cURL handle.
	 * @param string   $data    cURL request body.
	 * @return int Total bytes of data written.
	 */
	private function stream_body( $handle, $data ) {
		$data_length = strlen( $data );

		if ( $this->max_body_length && ( $this->bytes_written_total + $data_length ) > $this->max_body_length ) {
			$data_length = ( $this->max_body_length - $this->bytes_written_total );
			$data = substr( $data, 0, $data_length );
		}

		if ( $this->stream_handle ) {
			$bytes_written = fwrite( $this->stream_handle, $data );
		} else {
			$this->body .= $data;
			$bytes_written = $data_length;
		}

		$this->bytes_written_total += $bytes_written;

		// Upon event of this function returning less than strlen( $data ) curl will error with CURLE_WRITE_ERROR.
		return $bytes_written;
	}

	/**
	 * Determines whether this class can be used for retrieving a URL.
	 *
	 * @static
	 * @since 2.7.0
	 *
	 * @param array $args Optional. Array of request arguments. Default empty array.
	 * @return bool False means this class can not be used, true means it can.
	 */
	public static function test( $args = array() ) {
		if ( ! function_exists( 'curl_init' ) || ! function_exists( 'curl_exec' ) )
			return false;

		$is_ssl = isset( $args['ssl'] ) && $args['ssl'];

		if ( $is_ssl ) {
			$curl_version = curl_version();
			// Check whether this cURL version support SSL requests.
			if ( ! (CURL_VERSION_SSL & $curl_version['features']) )
				return false;
		}

		/**
		 * Filters whether cURL can be used as a transport for retrieving a URL.
		 *
		 * @since 2.7.0
		 *
		 * @param bool  $use_class Whether the class can be used. Default true.
		 * @param array $args      An array of request arguments.
		 */
		return apply_filters( 'use_curl_transport', true, $args );
	}
}