Http Component

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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.

For each request, it executes the callback function passed to the constructor with the respective request object and expects a respective response object in return.

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

In order to process any connections, the server needs to be attached to an instance of React\Socket\ServerInterface which emits underlying streaming connections in order to then parse incoming data as HTTP.

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(8080, $loop);
$server->listen($socket);

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

Similarly, you can also attach this to a React\Socket\SecureServer in order to start a secure HTTPS server like this:

$server = new Server($handler);

$socket = new React\Socket\Server(8080, $loop);
$socket = new React\Socket\SecureServer($socket, $loop, array(
    'local_cert' => __DIR__ . '/localhost.pem'
));

$server->listen($socket);

See also example #11 for more details.

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 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. The Response still needs to be created as described in the examples above.

See also request and response for more details (e.g. the request data body).

The Server supports 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 in the request header, it will emit an error event, send an HTTP error response to the client and close the connection:

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

The server will also emit an error event if you return an invalid type in the callback function or have a unhandled Exception or Throwable. If your callback function throws an Exception or Throwable, the Server will emit a RuntimeException and add the thrown exception as previous:

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

Note that the request object can also emit an error. Check out request for more details.

Request

An seen above, the Server class is responsible for handling incoming connections and then processing each incoming HTTP request.

The request object will be processed once the request headers have 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
   );
});

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 #2.

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 #3.

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

Currently the uploaded files are not added by the Server, but you can add these parameters by yourself using the given methods. The next versions of this project will cover these features.

Note that 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. 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() method can be used to access the request body stream. 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 the 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(). Instead, you should use the ReactPHP ReadableStreamInterface which gives you access to the incoming request body as the individual chunks arrive:

$server = new Server(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 #4 for more details.

The data event will be emitted whenever new data is available on the request body stream. The server automatically takes care of decoding chunked transfer encoding and will only emit the actual payload as data. In this case, the Transfer-Encoding header will be removed.

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 chunked data or the connection closes before the complete request stream has been received. The server will automatically pause() the connection 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 if you only want to know the request body size. This method returns the complete size of the request body 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). Note that this value may be null if the request body size is unknown in advance because the request message uses chunked transfer encoding.

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

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 #6 for more details.

Response

The callback function passed to the constructor of the Server 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"
    );
});

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, $reject) use ($request, $loop) {
        $loop->addTimer(1.5, function() use ($loop, $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.

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->emit('data', array(microtime(true) . PHP_EOL));
    });

    $loop->addTimer(5, function() use ($loop, $timer, $stream) {
        $loop->cancelTimer($timer);
        $stream->emit('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).

If the response body is a string, a Content-Length header will be added automatically. If the response body is a ReactPHP ReadableStreamInterface and you do not specify a Content-Length header, HTTP/1.1 responses will automatically use chunked transfer encoding and send the respective header (Transfer-Encoding: chunked) automatically. The server is responsible for handling Transfer-Encoding, so you SHOULD NOT pass this header yourself. If you know the length of your stream body, you MAY specify it like this instead:

$stream = new ThroughStream()
$server = new Server(function (ServerRequestInterface $request) use ($stream) {
    return new Response(
        200,
        array(
            'Content-Length' => '5',
            'Content-Type' => 'text/plain',
        ),
        $stream
    );
});

An invalid return value or an unhandled Exception or Throwable in the code of the callback function, will result in an 500 Internal Server Error message. Make sure to catch Exceptions or Throwables to create own response messages.

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

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.

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.

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.

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:^0.7.4

More details about version upgrades can be found in the CHANGELOG.

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.