content-control / classes / Base / Stream.php

Stream.php in Content Control – The Ultimate Content Restriction Plugin! Restrict Content, Create Conditional Blocks & More trunk, at classes/Base/Stream.php

186 lines 4.2 KB

Raw Download Zip

1	<?php
2	/**
3	* Plugin controller.
4	*
5	* @copyright (c) 2021, Code Atlantic LLC.
6	*
7	* @package ContentControl
8	*/
9
10	namespace ContentControl\Base;
11
12	defined( 'ABSPATH' ) \|\| exit;
13
14	/**
15	* HTTP Stream class.
16	*
17	* This class writes the `text/event-stream` wire format, not HTML. HTML
18	* escaping would corrupt SSE framing. Event names are reduced to the
19	* characters permitted by this implementation, non-string payloads are JSON
20	* encoded, and every payload line is emitted as a separate `data:` field.
21	* Content Control uses this only from capability- and nonce-protected
22	* administrative upgrade handlers.
23	*/
24	class Stream {
25
26	/**
27	* Stream name.
28	*
29	* @var string
30	*/
31	protected $stream_name;
32
33	/**
34	* Version.
35	*
36	* @var string
37	*/
38	const VERSION = '1.0.0';
39
40	/**
41	* Stream constructor.
42	*
43	* @param string $stream_name Stream name.
44	*/
45	public function __construct( $stream_name = 'stream' ) {
46	$this->stream_name = sanitize_key( $stream_name );
47
48	if ( empty( $this->stream_name ) ) {
49	$this->stream_name = 'stream';
50	}
51	}
52
53	/**
54	* Start SSE stream.
55	*
56	* @return void
57	*/
58	public function start() {
59	if ( headers_sent() ) {
60	// Do not start the stream if headers have already been sent.
61	return;
62	}
63
64	// Disable default disconnect checks.
65	ignore_user_abort( true );
66
67	// phpcs:disable WordPress.PHP.IniSet.Risky, WordPress.PHP.NoSilencedErrors.Discouraged
68	@ini_set( 'zlib.output_compression', '0' );
69	@ini_set( 'implicit_flush', '1' );
70
71	@ob_end_clean();
72	set_time_limit( 0 );
73	// phpcs:enable WordPress.PHP.IniSet.Risky, WordPress.PHP.NoSilencedErrors.Discouraged
74
75	$this->send_headers();
76	}
77
78	/**
79	* Send SSE headers.
80	*
81	* @return void
82	*/
83	public function send_headers() {
84	header( 'Content-Type: text/event-stream' );
85	header( 'Stream-Name: ' . $this->stream_name );
86	header( 'Cache-Control: no-cache' );
87	header( 'Connection: keep-alive' );
88	// Nginx: unbuffered responses suitable for Comet and HTTP streaming applications.
89	header( 'X-Accel-Buffering: no' );
90	$this->flush_buffers();
91	}
92
93	/**
94	* Flush buffers.
95	*
96	* Uses a micro delay to prevent the stream from flushing too quickly.
97	*
98	* @return void
99	*/
100	protected function flush_buffers() {
101	// This is for the buffer achieve the minimum size in order to flush data.
102
103	// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
104	echo str_repeat( ' ', 1024 * 8 ) . PHP_EOL;
105
106	flush(); // Unless both are called. Some browsers will still cache.
107
108	// Neccessary to prevent the stream from flushing too quickly.
109	usleep( 1000 );
110	}
111
112	/**
113	* Send general message/data to the client.
114	*
115	* @param mixed $data Data to send.
116	*
117	* @return void
118	*/
119	public function send_data( $data ) {
120	// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
121	echo $this->format_data( $data );
122	echo PHP_EOL;
123
124	$this->flush_buffers();
125	}
126
127	/**
128	* Send an event to the client.
129	*
130	* @param string $event Event name.
131	* @param mixed $data Data to send.
132	*
133	* @return void
134	*/
135	public function send_event( $event, $data = '' ) {
136	$event = preg_replace( '/[^a-zA-Z0-9_.:-]/', '', (string) $event );
137	$event = empty( $event ) ? 'message' : $event;
138
139	// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
140	echo 'event: ' . $event . PHP_EOL;
141	// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
142	echo $this->format_data( $data );
143	echo PHP_EOL;
144
145	$this->flush_buffers();
146	}
147
148	/**
149	* Format a value as one or more SSE data fields.
150	*
151	* @param mixed $data Data to format.
152	*
153	* @return string
154	*/
155	protected function format_data( $data ) {
156	$data = is_string( $data ) ? $data : \wp_json_encode( $data );
157	$data = is_string( $data ) ? $data : '';
158	$data = str_replace( [ "\r\n", "\r" ], "\n", $data );
159	$lines = explode( "\n", $data );
160
161	return implode( PHP_EOL, array_map( static function ( $line ) {
162	return 'data: ' . $line;
163	}, $lines ) ) . PHP_EOL;
164	}
165
166	/**
167	* Send an error to the client.
168	*
169	* @param array{message:string}\|string $error Error message.
170	*
171	* @return void
172	*/
173	public function send_error( $error ) {
174	$this->send_event( 'error', $error );
175	}
176
177	/**
178	* Check if the connection should abort.
179	*
180	* @return bool
181	*/
182	public function should_abort() {
183	return (bool) connection_aborted();
184	}
185	}
186