react/http

Event-driven, streaming plaintext HTTP and secure HTTPS server for ReactPHP

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github.com/reactphp/http

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v0.8.4 2019-01-16 07:26 UTC

README

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Event-driven, streaming plaintext HTTP and secure HTTPS server for ReactPHP.

Table of Contents

Quickstart example

This is an HTTP server which responds with Hello World! to every request.

$loop = React\EventLoop\Factory::create();

$server = new Server(function (ServerRequestInterface $request) {
    return new Response(
        200,
        array(
            'Content-Type' => 'text/plain'
        ),
        "Hello World!\n"
    );
});

$socket = new React\Socket\Server(8080, $loop);
$server->listen($socket);

$loop->run();

See also the examples.

Usage

Server

The Server class is responsible for handling incoming connections and then processing each incoming HTTP request.

It buffers and parses the complete incoming HTTP request in memory. Once the complete request has been received, it will invoke the request handler function. This request handler function needs to be passed to the constructor and will be invoked with the respective request object and expects a response object in return:

$server = new Server(function (ServerRequestInterface $request) {
    return new Response(
        200,
        array(
            'Content-Type' => 'text/plain'
        ),
        "Hello World!\n"
    );
});

Each incoming HTTP request message is always represented by the PSR-7 ServerRequestInterface, see also following request chapter for more details. Each outgoing HTTP response message is always represented by the PSR-7 ResponseInterface, see also following response chapter for more details.

In order to process any connections, the server needs to be attached to an instance of React\Socket\ServerInterface through the listen() method as described in the following chapter. In its most simple form, you can attach this to a React\Socket\Server in order to start a plaintext HTTP server like this:

$server = new Server($handler);

$socket = new React\Socket\Server('0.0.0.0:8080', $loop);
$server->listen($socket);

See also the listen() method and the first example for more details.

The Server class is built as a facade around the underlying StreamingServer to provide sane defaults for 80% of the use cases and is the recommended way to use this library unless you're sure you know what you're doing.

Unlike the underlying StreamingServer, this class buffers and parses the complete incoming HTTP request in memory. Once the complete request has been received, it will invoke the request handler function. This means the request passed to your request handler function will be fully compatible with PSR-7.

On the other hand, buffering complete HTTP requests in memory until they can be processed by your request handler function means that this class has to employ a number of limits to avoid consuming too much memory. In order to take the more advanced configuration out your hand, it respects setting from your php.ini to apply its default settings. This is a list of PHP settings this class respects with their respective default values:

memory_limit 128M
post_max_size 8M
enable_post_data_reading 1
max_input_nesting_level 64
max_input_vars 1000

file_uploads 1
upload_max_filesize 2M
max_file_uploads 20

In particular, the post_max_size setting limits how much memory a single HTTP request is allowed to consume while buffering its request body. On top of this, this class will try to avoid consuming more than 1/4 of your memory_limit for buffering multiple concurrent HTTP requests. As such, with the above default settings of 128M max, it will try to consume no more than 32M for buffering multiple concurrent HTTP requests. As a consequence, it will limit the concurrency to 4 HTTP requests with the above defaults.

It is imperative that you assign reasonable values to your PHP ini settings. It is usually recommended to either reduce the memory a single request is allowed to take (set post_max_size 1M or less) or to increase the total memory limit to allow for more concurrent requests (set memory_limit 512M or more). Failure to do so means that this class may have to disable concurrency and only handle one request at a time.

Internally, this class automatically assigns these limits to the middleware request handlers as described below. For more advanced use cases, you may also use the advanced StreamingServer and assign these middleware request handlers yourself as described in the following chapters.

StreamingServer

The advanced StreamingServer class is responsible for handling incoming connections and then processing each incoming HTTP request.

Unlike the Server class, it does not buffer and parse the incoming HTTP request body by default. This means that the request handler will be invoked with a streaming request body. Once the request headers have been received, it will invoke the request handler function. This request handler function needs to be passed to the constructor and will be invoked with the respective request object and expects a response object in return:

$server = new StreamingServer(function (ServerRequestInterface $request) {
    return new Response(
        200,
        array(
            'Content-Type' => 'text/plain'
        ),
        "Hello World!\n"
    );
});

Each incoming HTTP request message is always represented by the PSR-7 ServerRequestInterface, see also following request chapter for more details. Each outgoing HTTP response message is always represented by the PSR-7 ResponseInterface, see also following response chapter for more details.

In order to process any connections, the server needs to be attached to an instance of React\Socket\ServerInterface through the listen() method as described in the following chapter. In its most simple form, you can attach this to a React\Socket\Server in order to start a plaintext HTTP server like this:

$server = new StreamingServer($handler);

$socket = new React\Socket\Server('0.0.0.0:8080', $loop);
$server->listen($socket);

See also the listen() method and the first example for more details.

The StreamingServer class is considered advanced usage and unless you know what you're doing, you're recommended to use the Server class instead. The StreamingServer class is specifically designed to help with more advanced use cases where you want to have full control over consuming the incoming HTTP request body and concurrency settings.

In particular, this class does not buffer and parse the incoming HTTP request in memory. It will invoke the request handler function once the HTTP request headers have been received, i.e. before receiving the potentially much larger HTTP request body. This means the request passed to your request handler function may not be fully compatible with PSR-7. See also streaming request below for more details.

listen()

The listen(React\Socket\ServerInterface $socket): void method can be used to start processing connections from the given socket server. The given React\Socket\ServerInterface is responsible for emitting the underlying streaming connections. This HTTP server needs to be attached to it in order to process any connections and pase incoming streaming data as incoming HTTP request messages. In its most common form, you can attach this to a React\Socket\Server in order to start a plaintext HTTP server like this:

$server = new Server($handler);
// or
$server = new StreamingServer($handler);

$socket = new React\Socket\Server('0.0.0.0:8080', $loop);
$server->listen($socket);

This example will start listening for HTTP requests on the alternative HTTP port 8080 on all interfaces (publicly). As an alternative, it is very common to use a reverse proxy and let this HTTP server listen on the localhost (loopback) interface only by using the listen address 127.0.0.1:8080 instead. This way, you host your application(s) on the default HTTP port 80 and only route specific requests to this HTTP server.

Likewise, it's usually recommended to use a reverse proxy setup to accept secure HTTPS requests on default HTTPS port 443 (TLS termination) and only route plaintext requests to this HTTP server. As an alternative, you can also accept secure HTTPS requests with this HTTP server by attaching this to a React\Socket\Server using a secure TLS listen address, a certificate file and optional passphrase like this:

$server = new Server($handler);
// or
$server = new StreamingServer($handler);

$socket = new React\Socket\Server('tls://0.0.0.0:8443', $loop, array(
    'local_cert' => __DIR__ . '/localhost.pem'
));
$server->listen($socket);

See also example #11 for more details.

Request

As seen above, the Server and StreamingServer classes are responsible for handling incoming connections and then processing each incoming HTTP request.

The request object will be processed once the request has been received by the client. This request object implements the PSR-7 ServerRequestInterface which in turn extends the PSR-7 RequestInterface and will be passed to the callback function like this.

$server = new Server(function (ServerRequestInterface $request) {
   $body = "The method of the request is: " . $request->getMethod();
   $body .= "The requested path is: " . $request->getUri()->getPath();

   return new Response(
       200,
       array(
           'Content-Type' => 'text/plain'
       ),
       $body
   );
});

For more details about the request object, also check out the documentation of PSR-7 ServerRequestInterface and PSR-7 RequestInterface.

Request parameters

The getServerParams(): mixed[] method can be used to get server-side parameters similar to the $_SERVER variable. The following parameters are currently available:

  • REMOTE_ADDR The IP address of the request sender
  • REMOTE_PORT Port of the request sender
  • SERVER_ADDR The IP address of the server
  • SERVER_PORT The port of the server
  • REQUEST_TIME Unix timestamp when the complete request header has been received, as integer similar to time()
  • REQUEST_TIME_FLOAT Unix timestamp when the complete request header has been received, as float similar to microtime(true)
  • HTTPS Set to 'on' if the request used HTTPS, otherwise it won't be set
$server = new Server(function (ServerRequestInterface $request) {
    $body = "Your IP is: " . $request->getServerParams()['REMOTE_ADDR'];

    return new Response(
        200,
        array(
            'Content-Type' => 'text/plain'
        ),
        $body
    );
});

See also example #3.

Advanced: Note that address parameters will not be set if you're listening on a Unix domain socket (UDS) path as this protocol lacks the concept of host/port.

Query parameters

The getQueryParams(): array method can be used to get the query parameters similiar to the $_GET variable.

$server = new Server(function (ServerRequestInterface $request) {
    $queryParams = $request->getQueryParams();

    $body = 'The query parameter "foo" is not set. Click the following link ';
    $body .= '<a href="/?foo=bar">to use query parameter in your request</a>';

    if (isset($queryParams['foo'])) {
        $body = 'The value of "foo" is: ' . htmlspecialchars($queryParams['foo']);
    }

    return new Response(
        200,
        array(
            'Content-Type' => 'text/html'
        ),
        $body
    );
});

The response in the above example will return a response body with a link. The URL contains the query parameter foo with the value bar. Use htmlentities like in this example to prevent Cross-Site Scripting (abbreviated as XSS).

See also example #4.

Request body

If you're using the Server, then the request object will be buffered and parsed in memory and contains the full request body. This includes the parsed request body and any file uploads.

If you're using the advanced StreamingServer class, jump to the next chapter to learn more about how to process a streaming request.

As stated above, each incoming HTTP request is always represented by the PSR-7 ServerRequestInterface. This interface provides several methods that are useful when working with the incoming request body as described below.

The getParsedBody(): null|array|object method can be used to get the parsed request body, similar to PHP's $_POST variable. This method may return a (possibly nested) array structure with all body parameters or a null value if the request body could not be parsed. By default, this method will only return parsed data for requests using Content-Type: application/x-www-form-urlencoded or Content-Type: multipart/form-data request headers (commonly used for POST requests for HTML form submission data).

$server = new Server(function (ServerRequestInterface $request) {
    $name = $request->getParsedBody()['name'] ?? 'anonymous';

    return new Response(
        200,
        array(),
        "Hello $name!\n"
    );
});

See also example #12 for more details.

The getBody(): StreamInterface method can be used to get the raw data from this request body, similar to PHP's php://input stream. This method returns an instance of the request body represented by the PSR-7 StreamInterface. This is particularly useful when using a custom request body that will not otherwise be parsed by default, such as a JSON (Content-Type: application/json) or an XML (Content-Type: application/xml) request body (which is commonly used for POST, PUT or PATCH requests in JSON-based or RESTful/RESTish APIs).

$server = new Server(function (ServerRequestInterface $request) {
    $data = json_decode((string)$request->getBody());
    $name = $data->name ?? 'anonymous';

    return new Response(
        200,
        array('Content-Type' => 'application/json'),
        json_encode(['message' => "Hello $name!"])
    );
});

See also example #9 for more details.

The getUploadedFiles(): array method can be used to get the uploaded files in this request, similar to PHP's $_FILES variable. This method returns a (possibly nested) array structure with all file uploads, each represented by the PSR-7 UploadedFileInterface. This array will only be filled when using the Content-Type: multipart/form-data request header (commonly used for POST requests for HTML file uploads).

$server = new Server(function (ServerRequestInterface $request) {
    $files = $request->getUploadedFiles();
    $name = isset($files['avatar']) ? $files['avatar']->getClientFilename() : 'nothing';

    return new Response(
        200,
        array(),
        "Uploaded $name\n"
    );
});

See also example #12 for more details.

The getSize(): ?int method can be used to get the size of the request body, similar to PHP's $_SERVER['CONTENT_LENGTH'] variable. This method returns the complete size of the request body measured in number of bytes as defined by the message boundaries. This value may be 0 if the request message does not contain a request body (such as a simple GET request). This method operates on the buffered request body, i.e. the request body size is always known, even when the request does not specify a Content-Length request header or when using Transfer-Encoding: chunked for HTTP/1.1 requests.

Note: The Server automatically takes care of handling requests with the additional Expect: 100-continue request header. When HTTP/1.1 clients want to send a bigger request body, they MAY send only the request headers with an additional Expect: 100-continue request header and wait before sending the actual (large) message body. In this case the server will automatically send an intermediary HTTP/1.1 100 Continue response to the client. This ensures you will receive the request body without a delay as expected.

Streaming request

If you're using the advanced StreamingServer, the request object will be processed once the request headers have been received. This means that this happens irrespective of (i.e. before) receiving the (potentially much larger) request body.

If you're using the Server class, jump to the previous chapter to learn more about how to process a buffered request body.

While this may be uncommon in the PHP ecosystem, this is actually a very powerful approach that gives you several advantages not otherwise possible:

  • React to requests before receiving a large request body, such as rejecting an unauthenticated request or one that exceeds allowed message lengths (file uploads).
  • Start processing parts of the request body before the remainder of the request body arrives or if the sender is slowly streaming data.
  • Process a large request body without having to buffer anything in memory, such as accepting a huge file upload or possibly unlimited request body stream.

The getBody(): StreamInterface method can be used to access the request body stream. In the streaming mode, this method returns a stream instance that implements both the PSR-7 StreamInterface and the ReactPHP ReadableStreamInterface. However, most of the PSR-7 StreamInterface methods have been designed under the assumption of being in control of a synchronous request body. Given that this does not apply to this server, the following PSR-7 StreamInterface methods are not used and SHOULD NOT be called: tell(), eof(), seek(), rewind(), write() and read(). If this is an issue for your use case and/or you want to access uploaded files, it's highly recommended to use a buffered request body or use the RequestBodyBufferMiddleware instead. The ReactPHP ReadableStreamInterface gives you access to the incoming request body as the individual chunks arrive:

$server = new StreamingServer(function (ServerRequestInterface $request) {
    return new Promise(function ($resolve, $reject) use ($request) {
        $contentLength = 0;
        $request->getBody()->on('data', function ($data) use (&$contentLength) {
            $contentLength += strlen($data);
        });

        $request->getBody()->on('end', function () use ($resolve, &$contentLength){
            $response = new Response(
                200,
                array(
                    'Content-Type' => 'text/plain'
                ),
                "The length of the submitted request body is: " . $contentLength
            );
            $resolve($response);
        });

        // an error occures e.g. on invalid chunked encoded data or an unexpected 'end' event
        $request->getBody()->on('error', function (\Exception $exception) use ($resolve, &$contentLength) {
            $response = new Response(
                400,
                array(
                    'Content-Type' => 'text/plain'
                ),
                "An error occured while reading at length: " . $contentLength
            );
            $resolve($response);
        });
    });
});

The above example simply counts the number of bytes received in the request body. This can be used as a skeleton for buffering or processing the request body.

See also example #13 for more details.

The data event will be emitted whenever new data is available on the request body stream. The server also automatically takes care of decoding any incoming requests using Transfer-Encoding: chunked and will only emit the actual payload as data.

The end event will be emitted when the request body stream terminates successfully, i.e. it was read until its expected end.

The error event will be emitted in case the request stream contains invalid data for Transfer-Encoding: chunked or when the connection closes before the complete request stream has been received. The server will automatically stop reading from the connection and discard all incoming data instead of closing it. A response message can still be sent (unless the connection is already closed).

A close event will be emitted after an error or end event.

For more details about the request body stream, check out the documentation of ReactPHP ReadableStreamInterface.

The getSize(): ?int method can be used to get the size of the request body, similar to PHP's $_SERVER['CONTENT_LENGTH'] variable. This method returns the complete size of the request body measured in number of bytes as defined by the message boundaries. This value may be 0 if the request message does not contain a request body (such as a simple GET request). This method operates on the streaming request body, i.e. the request body size may be unknown (null) when using Transfer-Encoding: chunked for HTTP/1.1 requests.

$server = new StreamingServer(function (ServerRequestInterface $request) {
    $size = $request->getBody()->getSize();
    if ($size === null) {
        $body = 'The request does not contain an explicit length.';
        $body .= 'This example does not accept chunked transfer encoding.';

        return new Response(
            411,
            array(
                'Content-Type' => 'text/plain'
            ),
            $body
        );
    }

    return new Response(
        200,
        array(
            'Content-Type' => 'text/plain'
        ),
        "Request body size: " . $size . " bytes\n"
    );
});

Note: The StreamingServer automatically takes care of handling requests with the additional Expect: 100-continue request header. When HTTP/1.1 clients want to send a bigger request body, they MAY send only the request headers with an additional Expect: 100-continue request header and wait before sending the actual (large) message body. In this case the server will automatically send an intermediary HTTP/1.1 100 Continue response to the client. This ensures you will receive the streaming request body without a delay as expected.

Request method

Note that the server supports any request method (including custom and non- standard ones) and all request-target formats defined in the HTTP specs for each respective method, including normal origin-form requests as well as proxy requests in absolute-form and authority-form. The getUri(): UriInterface method can be used to get the effective request URI which provides you access to individiual URI components. Note that (depending on the given request-target) certain URI components may or may not be present, for example the getPath(): string method will return an empty string for requests in asterisk-form or authority-form. Its getHost(): string method will return the host as determined by the effective request URI, which defaults to the local socket address if a HTTP/1.0 client did not specify one (i.e. no Host header). Its getScheme(): string method will return http or https depending on whether the request was made over a secure TLS connection to the target host.

The Host header value will be sanitized to match this host component plus the port component only if it is non-standard for this URI scheme.

You can use getMethod(): string and getRequestTarget(): string to check this is an accepted request and may want to reject other requests with an appropriate error code, such as 400 (Bad Request) or 405 (Method Not Allowed).

The CONNECT method is useful in a tunneling setup (HTTPS proxy) and not something most HTTP servers would want to care about. Note that if you want to handle this method, the client MAY send a different request-target than the Host header value (such as removing default ports) and the request-target MUST take precendence when forwarding.

Cookie parameters

The getCookieParams(): string[] method can be used to get all cookies sent with the current request.

$server = new Server(function (ServerRequestInterface $request) {
    $key = 'react\php';

    if (isset($request->getCookieParams()[$key])) {
        $body = "Your cookie value is: " . $request->getCookieParams()[$key];

        return new Response(
            200,
            array(
                'Content-Type' => 'text/plain'
            ),
            $body
        );
    }

    return new Response(
        200,
        array(
            'Content-Type' => 'text/plain',
            'Set-Cookie' => urlencode($key) . '=' . urlencode('test;more')
        ),
        "Your cookie has been set."
    );
});

The above example will try to set a cookie on first access and will try to print the cookie value on all subsequent tries. Note how the example uses the urlencode() function to encode non-alphanumeric characters. This encoding is also used internally when decoding the name and value of cookies (which is in line with other implementations, such as PHP's cookie functions).

See also example #5 for more details.

Invalid request

The Server and StreamingServer classes support both HTTP/1.1 and HTTP/1.0 request messages. If a client sends an invalid request message, uses an invalid HTTP protocol version or sends an invalid Transfer-Encoding request header value, the server will automatically send a 400 (Bad Request) HTTP error response to the client and close the connection. On top of this, it will emit an error event that can be used for logging purposes like this:

$server->on('error', function (Exception $e) {
    echo 'Error: ' . $e->getMessage() . PHP_EOL;
});

Note that the server will also emit an error event if you do not return a valid response object from your request handler function. See also invalid response for more details.

Response

The callback function passed to the constructor of the Server or advanced StreamingServer is responsible for processing the request and returning a response, which will be delivered to the client. This function MUST return an instance implementing PSR-7 ResponseInterface object or a ReactPHP Promise which will resolve a PSR-7 ResponseInterface object.

You will find a Response class which implements the PSR-7 ResponseInterface in this project. We use instantiation of this class in our projects, but feel free to use any implemantation of the PSR-7 ResponseInterface you prefer.

$server = new Server(function (ServerRequestInterface $request) {
    return new Response(
        200,
        array(
            'Content-Type' => 'text/plain'
        ),
        "Hello World!\n"
    );
});

Deferred response

The example above returns the response directly, because it needs no time to be processed. Using a database, the file system or long calculations (in fact every action that will take >=1ms) to create your response, will slow down the server. To prevent this you SHOULD use a ReactPHP Promise. This example shows how such a long-term action could look like:

$server = new Server(function (ServerRequestInterface $request) use ($loop) {
    return new Promise(function ($resolve, $reject) use ($loop) {
        $loop->addTimer(1.5, function() use ($resolve) {
            $response = new Response(
                200,
                array(
                    'Content-Type' => 'text/plain'
                ),
                "Hello world"
            );
            $resolve($response);
        });
    });
});

The above example will create a response after 1.5 second. This example shows that you need a promise, if your response needs time to created. The ReactPHP Promise will resolve in a Response object when the request body ends. If the client closes the connection while the promise is still pending, the promise will automatically be cancelled. The promise cancellation handler can be used to clean up any pending resources allocated in this case (if applicable). If a promise is resolved after the client closes, it will simply be ignored.

Streaming response

The Response class in this project supports to add an instance which implements the ReactPHP ReadableStreamInterface for the response body. So you are able stream data directly into the response body. Note that other implementations of the PSR-7 ResponseInterface likely only support strings.

$server = new Server(function (ServerRequestInterface $request) use ($loop) {
    $stream = new ThroughStream();

    $timer = $loop->addPeriodicTimer(0.5, function () use ($stream) {
        $stream->write(microtime(true) . PHP_EOL);
    });

    $loop->addTimer(5, function() use ($loop, $timer, $stream) {
        $loop->cancelTimer($timer);
        $stream->end();
    });

    return new Response(
        200,
        array(
            'Content-Type' => 'text/plain'
        ),
        $stream
    );
});

The above example will emit every 0.5 seconds the current Unix timestamp with microseconds as float to the client and will end after 5 seconds. This is just a example you could use of the streaming, you could also send a big amount of data via little chunks or use it for body data that needs to calculated.

If the request handler resolves with a response stream that is already closed, it will simply send an empty response body. If the client closes the connection while the stream is still open, the response stream will automatically be closed. If a promise is resolved with a streaming body after the client closes, the response stream will automatically be closed. The close event can be used to clean up any pending resources allocated in this case (if applicable).

Note that special care has to be taken if you use a body stream instance that implements ReactPHP's DuplexStreamInterface (such as the ThroughStream in the above example).

For most cases, this will simply only consume its readable side and forward (send) any data that is emitted by the stream, thus entirely ignoring the writable side of the stream. If however this is either a 101 (Switching Protocols) response or a 2xx (Successful) response to a CONNECT method, it will also write data to the writable side of the stream. This can be avoided by either rejecting all requests with the CONNECT method (which is what most normal origin HTTP servers would likely do) or or ensuring that only ever an instance of ReadableStreamInterface is used.

The 101 (Switching Protocols) response code is useful for the more advanced Upgrade requests, such as upgrading to the WebSocket protocol or implementing custom protocol logic that is out of scope of the HTTP specs and this HTTP library. If you want to handle the Upgrade: WebSocket header, you will likely want to look into using Ratchet instead. If you want to handle a custom protocol, you will likely want to look into the HTTP specs and also see examples #31 and #32 for more details. In particular, the 101 (Switching Protocols) response code MUST NOT be used unless you send an Upgrade response header value that is also present in the corresponding HTTP/1.1 Upgrade request header value. The server automatically takes care of sending a Connection: upgrade header value in this case, so you don't have to.

The CONNECT method is useful in a tunneling setup (HTTPS proxy) and not something most origin HTTP servers would want to care about. The HTTP specs define an opaque "tunneling mode" for this method and make no use of the message body. For consistency reasons, this library uses a DuplexStreamInterface in the response body for tunneled application data. This implies that that a 2xx (Successful) response to a CONNECT request can in fact use a streaming response body for the tunneled application data, so that any raw data the client sends over the connection will be piped through the writable stream for consumption. Note that while the HTTP specs make no use of the request body for CONNECT requests, one may still be present. Normal request body processing applies here and the connection will only turn to "tunneling mode" after the request body has been processed (which should be empty in most cases). See also example #22 for more details.

Response length

If the response body size is known, a Content-Length response header will be added automatically. This is the most common use case, for example when using a string response body like this:

$server = new Server(function (ServerRequestInterface $request) {
    return new Response(
        200,
        array(
            'Content-Type' => 'text/plain'
        ),
        "Hello World!\n"
    );
});

If the response body size is unknown, a Content-Length response header can not be added automatically. When using a streaming response without an explicit Content-Length response header, outgoing HTTP/1.1 response messages will automatically use Transfer-Encoding: chunked while legacy HTTP/1.0 response messages will contain the plain response body. If you know the length of your streaming response body, you MAY want to specify it explicitly like this:

$server = new Server(function (ServerRequestInterface $request) use ($loop) {
    $stream = new ThroughStream();

    $loop->addTimer(2.0, function () use ($stream) {
        $stream->end("Hello World!\n");
    });

    return new Response(
        200,
        array(
            'Content-Length' => '13',
            'Content-Type' => 'text/plain',
        ),
        $stream
    );
});

Any response to a HEAD request and any response with a 1xx (Informational), 204 (No Content) or 304 (Not Modified) status code will not include a message body as per the HTTP specs. This means that your callback does not have to take special care of this and any response body will simply be ignored.

Similarly, any 2xx (Successful) response to a CONNECT request, any response with a 1xx (Informational) or 204 (No Content) status code will not include a Content-Length or Transfer-Encoding header as these do not apply to these messages. Note that a response to a HEAD request and any response with a 304 (Not Modified) status code MAY include these headers even though the message does not contain a response body, because these header would apply to the message if the same request would have used an (unconditional) GET.

Invalid response

As stated above, each outgoing HTTP response is always represented by the PSR-7 ResponseInterface. If your request handler function returns an invalid value or throws an unhandled Exception or Throwable, the server will automatically send a 500 (Internal Server Error) HTTP error response to the client. On top of this, it will emit an error event that can be used for logging purposes like this:

$server->on('error', function (Exception $e) {
    echo 'Error: ' . $e->getMessage() . PHP_EOL;
    if ($e->getPrevious() !== null) {
        echo 'Previous: ' . $e->getPrevious()->getMessage() . PHP_EOL;
    }
});

Note that the server will also emit an error event if the client sends an invalid HTTP request that never reaches your request handler function. See also invalid request for more details. Additionally, a streaming request body can also emit an error event on the request body.

The server will only send a very generic 500 (Interval Server Error) HTTP error response without any further details to the client if an unhandled error occurs. While we understand this might make initial debugging harder, it also means that the server does not leak any application details or stack traces to the outside by default. It is usually recommended to catch any Exception or Throwable within your request handler function or alternatively use a middleware to avoid this generic error handling and create your own HTTP response message instead.

Default response headers

After the return in the callback function the response will be processed by the Server or StreamingServer respectively. They will add the protocol version of the request, so you don't have to.

A Date header will be automatically added with the system date and time if none is given. You can add a custom Date header yourself like this:

$server = new Server(function (ServerRequestInterface $request) {
    return new Response(
        200,
        array(
            'Date' => date('D, d M Y H:i:s T')
        )
    );
});

If you don't have a appropriate clock to rely on, you should unset this header with an empty string:

$server = new Server(function (ServerRequestInterface $request) {
    return new Response(
        200,
        array(
            'Date' => ''
        )
    );
});

Note that it will automatically assume a X-Powered-By: react/alpha header unless your specify a custom X-Powered-By header yourself:

$server = new Server(function (ServerRequestInterface $request) {
    return new Response(
        200,
        array(
            'X-Powered-By' => 'PHP 3'
        )
    );
});

If you do not want to send this header at all, you can use an empty string as value like this:

$server = new Server(function (ServerRequestInterface $request) {
    return new Response(
        200,
        array(
            'X-Powered-By' => ''
        )
    );
});

Note that persistent connections (Connection: keep-alive) are currently not supported. As such, HTTP/1.1 response messages will automatically include a Connection: close header, irrespective of what header values are passed explicitly.

Middleware

As documented above, the Server and advanced StreamingServer accept a single request handler argument that is responsible for processing an incoming HTTP request and then creating and returning an outgoing HTTP response.

Many common use cases involve validating, processing, manipulating the incoming HTTP request before passing it to the final business logic request handler. As such, this project supports the concept of middleware request handlers.

A middleware request handler is expected to adhere the following rules:

  • It is a valid callable.
  • It accepts ServerRequestInterface as first argument and an optional callable as second argument.
  • It returns either:
    • An instance implementing ResponseInterface for direct consumption.
    • Any promise which can be consumed by Promise\resolve() resolving to a ResponseInterface for deferred consumption.
    • It MAY throw an Exception (or return a rejected promise) in order to signal an error condition and abort the chain.
  • It calls $next($request) to continue processing the next middleware request handler or returns explicitly without calling $next to abort the chain.
    • The $next request handler (recursively) invokes the next request handler from the chain with the same logic as above and returns (or throws) as above.
    • The $request may be modified prior to calling $next($request) to change the incoming request the next middleware operates on.
    • The $next return value may be consumed to modify the outgoing response.
    • The $next request handler MAY be called more than once if you want to implement custom "retry" logic etc.

Note that this very simple definition allows you to use either anonymous functions or any classes that use the magic __invoke() method. This allows you to easily create custom middleware request handlers on the fly or use a class based approach to ease using existing middleware implementations.

While this project does provide the means to use middleware implementations, it does not aim to define how middleware implementations should look like. We realize that there's a vivid ecosystem of middleware implementations and ongoing effort to standardize interfaces between these with PSR-15 (HTTP Server Request Handlers) and support this goal. As such, this project only bundles a few middleware implementations that are required to match PHP's request behavior (see below) and otherwise actively encourages Third-Party Middleware implementations.

In order to use middleware request handlers, simply pass an array with all callables as defined above to the Server or StreamingServer respectively. The following example adds a middleware request handler that adds the current time to the request as a header (Request-Time) and a final request handler that always returns a 200 code without a body:

$server = new Server(array(
    function (ServerRequestInterface $request, callable $next) {
        $request = $request->withHeader('Request-Time', time());
        return $next($request);
    },
    function (ServerRequestInterface $request) {
        return new Response(200);
    }
));

Note how the middleware request handler and the final request handler have a very simple (and similar) interface. The only difference is that the final request handler does not receive a $next handler.

Similarly, you can use the result of the $next middleware request handler function to modify the outgoing response. Note that as per the above documentation, the $next middleware request handler may return a ResponseInterface directly or one wrapped in a promise for deferred resolution. In order to simplify handling both paths, you can simply wrap this in a Promise\resolve() call like this:

$server = new Server(array(
    function (ServerRequestInterface $request, callable $next) {
        $promise = React\Promise\resolve($next($request));
        return $promise->then(function (ResponseInterface $response) {
            return $response->withHeader('Content-Type', 'text/html');
        });
    },
    function (ServerRequestInterface $request) {
        return new Response(200);
    }
));

Note that the $next middleware request handler may also throw an Exception (or return a rejected promise) as described above. The previous example does not catch any exceptions and would thus signal an error condition to the Server. Alternatively, you can also catch any Exception to implement custom error handling logic (or logging etc.) by wrapping this in a Promise like this:

$server = new Server(array(
    function (ServerRequestInterface $request, callable $next) {
        $promise = new React\Promise\Promise(function ($resolve) use ($next, $request) {
            $resolve($next($request));
        });
        return $promise->then(null, function (Exception $e) {
            return new Response(
                500,
                array(),
                'Internal error: ' . $e->getMessage()
            );
        });
    },
    function (ServerRequestInterface $request) {
        if (mt_rand(0, 1) === 1) {
            throw new RuntimeException('Database error');
        }
        return new Response(200);
    }
));

LimitConcurrentRequestsMiddleware

The LimitConcurrentRequestsMiddleware can be used to limit how many next handlers can be executed concurrently.

If this middleware is invoked, it will check if the number of pending handlers is below the allowed limit and then simply invoke the next handler and it will return whatever the next handler returns (or throws).

If the number of pending handlers exceeds the allowed limit, the request will be queued (and its streaming body will be paused) and it will return a pending promise. Once a pending handler returns (or throws), it will pick the oldest request from this queue and invokes the next handler (and its streaming body will be resumed).

The following example shows how this middleware can be used to ensure no more than 10 handlers will be invoked at once:

$server = new Server(array(
    new LimitConcurrentRequestsMiddleware(10),
    $handler
));

Similarly, this middleware is often used in combination with the RequestBodyBufferMiddleware (see below) to limit the total number of requests that can be buffered at once:

$server = new StreamingServer(array(
    new LimitConcurrentRequestsMiddleware(100), // 100 concurrent buffering handlers
    new RequestBodyBufferMiddleware(2 * 1024 * 1024), // 2 MiB per request
    new RequestBodyParserMiddleware(),
    $handler
));

More sophisticated examples include limiting the total number of requests that can be buffered at once and then ensure the actual request handler only processes one request after another without any concurrency:

$server = new StreamingServer(array(
    new LimitConcurrentRequestsMiddleware(100), // 100 concurrent buffering handlers
    new RequestBodyBufferMiddleware(2 * 1024 * 1024), // 2 MiB per request
    new RequestBodyParserMiddleware(),
    new LimitConcurrentRequestsMiddleware(1), // only execute 1 handler (no concurrency)
    $handler
));

RequestBodyBufferMiddleware

One of the built-in middleware is the RequestBodyBufferMiddleware which can be used to buffer the whole incoming request body in memory. This can be useful if full PSR-7 compatibility is needed for the request handler and the default streaming request body handling is not needed. The constructor accepts one optional argument, the maximum request body size. When one isn't provided it will use post_max_size (default 8 MiB) from PHP's configuration. (Note that the value from your matching SAPI will be used, which is the CLI configuration in most cases.)

Any incoming request that has a request body that exceeds this limit will be accepted, but its request body will be discarded (empty request body). This is done in order to avoid having to keep an incoming request with an excessive size (for example, think of a 2 GB file upload) in memory. This allows the next middleware handler to still handle this request, but it will see an empty request body. This is similar to PHP's default behavior, where the body will not be parsed if this limit is exceeded. However, unlike PHP's default behavior, the raw request body is not available via php://input.

The RequestBodyBufferMiddleware will buffer requests with bodies of known size (i.e. with Content-Length header specified) as well as requests with bodies of unknown size (i.e. with Transfer-Encoding: chunked header).

All requests will be buffered in memory until the request body end has been reached and then call the next middleware handler with the complete, buffered request. Similarly, this will immediately invoke the next middleware handler for requests that have an empty request body (such as a simple GET request) and requests that are already buffered (such as due to another middleware).

Note that the given buffer size limit is applied to each request individually. This means that if you allow a 2 MiB limit and then receive 1000 concurrent requests, up to 2000 MiB may be allocated for these buffers alone. As such, it's highly recommended to use this along with the LimitConcurrentRequestsMiddleware (see above) to limit the total number of concurrent requests.

Usage:

$server = new StreamingServer(array(
    new LimitConcurrentRequestsMiddleware(100), // 100 concurrent buffering handlers
    new RequestBodyBufferMiddleware(16 * 1024 * 1024), // 16 MiB
    function (ServerRequestInterface $request) {
        // The body from $request->getBody() is now fully available without the need to stream it 
        return new Response(200);
    },
));

RequestBodyParserMiddleware

The RequestBodyParserMiddleware takes a fully buffered request body (generally from RequestBodyBufferMiddleware), and parses the form values and file uploads from the incoming HTTP request body.

This middleware handler takes care of applying values from HTTP requests that use Content-Type: application/x-www-form-urlencoded or Content-Type: multipart/form-data to resemble PHP's default superglobals $_POST and $_FILES. Instead of relying on these superglobals, you can use the $request->getParsedBody() and $request->getUploadedFiles() methods as defined by PSR-7.

Accordingly, each file upload will be represented as instance implementing UploadedFileInterface. Due to its blocking nature, the moveTo() method is not available and throws a RuntimeException instead. You can use $contents = (string)$file->getStream(); to access the file contents and persist this to your favorite data store.

$handler = function (ServerRequestInterface $request) {
    // If any, parsed form fields are now available from $request->getParsedBody()
    $body = $request->getParsedBody();
    $name = isset($body['name']) ? $body['name'] : 'unnamed';

    $files = $request->getUploadedFiles();
    $avatar = isset($files['avatar']) ? $files['avatar'] : null;
    if ($avatar instanceof UploadedFileInterface) {
        if ($avatar->getError() === UPLOAD_ERR_OK) {
            $uploaded = $avatar->getSize() . ' bytes';
        } elseif ($avatar->getError() === UPLOAD_ERR_INI_SIZE) {
            $uploaded = 'file too large';
        } else {
            $uploaded = 'with error';
        }
    } else {
        $uploaded = 'nothing';
    }

    return new Response(
        200,
        array(
            'Content-Type' => 'text/plain'
        ),
        $name . ' uploaded ' . $uploaded
    );
};

$server = new StreamingServer(array((
    new LimitConcurrentRequestsMiddleware(100), // 100 concurrent buffering handlers
    new RequestBodyBufferMiddleware(16 * 1024 * 1024), // 16 MiB
    new RequestBodyParserMiddleware(),
    $handler
));

See also example #12 for more details.

By default, this middleware respects the upload_max_filesize (default 2M) ini setting. Files that exceed this limit will be rejected with an UPLOAD_ERR_INI_SIZE error. You can control the maximum filesize for each individual file upload by explicitly passing the maximum filesize in bytes as the first parameter to the constructor like this:

new RequestBodyParserMiddleware(8 * 1024 * 1024); // 8 MiB limit per file

By default, this middleware respects the file_uploads (default 1) and max_file_uploads (default 20) ini settings. These settings control if any and how many files can be uploaded in a single request. If you upload more files in a single request, additional files will be ignored and the getUploadedFiles() method returns a truncated array. Note that upload fields left blank on submission do not count towards this limit. You can control the maximum number of file uploads per request by explicitly passing the second parameter to the constructor like this:

new RequestBodyParserMiddleware(10 * 1024, 100); // 100 files with 10 KiB each

Note that this middleware handler simply parses everything that is already buffered in the request body. It is imperative that the request body is buffered by a prior middleware handler as given in the example above. This previous middleware handler is also responsible for rejecting incoming requests that exceed allowed message sizes (such as big file uploads). The RequestBodyBufferMiddleware used above simply discards excessive request bodies, resulting in an empty body. If you use this middleware without buffering first, it will try to parse an empty (streaming) body and may thus assume an empty data structure. See also RequestBodyBufferMiddleware for more details.

PHP's MAX_FILE_SIZE hidden field is respected by this middleware. Files that exceed this limit will be rejected with an UPLOAD_ERR_FORM_SIZE error.

This middleware respects the max_input_vars (default 1000) and max_input_nesting_level (default 64) ini settings.

Note that this middleware ignores the enable_post_data_reading (default 1) ini setting because it makes little sense to respect here and is left up to higher-level implementations. If you want to respect this setting, you have to check its value and effectively avoid using this middleware entirely.

Third-Party Middleware

While this project does provide the means to use middleware implementations (see above), it does not aim to define how middleware implementations should look like. We realize that there's a vivid ecosystem of middleware implementations and ongoing effort to standardize interfaces between these with PSR-15 (HTTP Server Request Handlers) and support this goal. As such, this project only bundles a few middleware implementations that are required to match PHP's request behavior (see above) and otherwise actively encourages third-party middleware implementations.

While we would love to support PSR-15 directy in react/http, we understand that this interface does not specifically target async APIs and as such does not take advantage of promises for deferred responses. The gist of this is that where PSR-15 enforces a ResponseInterface return value, we also accept a PromiseInterface<ResponseInterface>. As such, we suggest using the external PSR-15 middleware adapter that uses on the fly monkey patching of these return values which makes using most PSR-15 middleware possible with this package without any changes required.

Other than that, you can also use the above middleware definition to create custom middleware. A non-exhaustive list of third-party middleware can be found at the middleware wiki. If you build or know a custom middleware, make sure to let the world know and feel free to add it to this list.

Install

The recommended way to install this library is through Composer. New to Composer?

This will install the latest supported version:

$ composer require react/http:^0.8.4

See also the CHANGELOG for details about version upgrades.

This project aims to run on any platform and thus does not require any PHP extensions and supports running on legacy PHP 5.3 through current PHP 7+ and HHVM. It's highly recommended to use PHP 7+ for this project.

Tests

To run the test suite, you first need to clone this repo and then install all dependencies through Composer:

$ composer install

To run the test suite, go to the project root and run:

$ php vendor/bin/phpunit

License

MIT, see LICENSE file.