Async HTTP proxy connector, use any TCP/IP-based protocol through an HTTP CONNECT proxy server, built on top of ReactPHP.
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README.md

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Async HTTP proxy connector, use any TCP/IP-based protocol through an HTTP CONNECT proxy server, built on top of ReactPHP.

HTTP CONNECT proxy servers (also commonly known as "HTTPS proxy" or "SSL proxy") are commonly used to tunnel HTTPS traffic through an intermediary ("proxy"), to conceal the origin address (anonymity) or to circumvent address blocking (geoblocking). While many (public) HTTP CONNECT proxy servers often limit this to HTTPS port 443 only, this can technically be used to tunnel any TCP/IP-based protocol (HTTP, SMTP, IMAP etc.). This library provides a simple API to create these tunneled connections for you. Because it implements ReactPHP's standard ConnectorInterface, it can simply be used in place of a normal connector. This makes it fairly simple to add HTTP CONNECT proxy support to pretty much any existing higher-level protocol implementation.

  • Async execution of connections - Send any number of HTTP CONNECT requests in parallel and process their responses as soon as results come in. The Promise-based design provides a sane interface to working with out of bound responses and possible connection errors.
  • Standard interfaces - Allows easy integration with existing higher-level components by implementing ReactPHP's standard ConnectorInterface.
  • Lightweight, SOLID design - Provides a thin abstraction that is just good enough and does not get in your way. Builds on top of well-tested components and well-established concepts instead of reinventing the wheel.
  • Good test coverage - Comes with an automated tests suite and is regularly tested against actual proxy servers in the wild.

Table of contents

Quickstart example

The following example code demonstrates how this library can be used to send a secure HTTPS request to google.com through a local HTTP proxy server:

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

$proxy = new ProxyConnector('127.0.0.1:8080', new Connector($loop));
$connector = new Connector($loop, array(
    'tcp' => $proxy,
    'timeout' => 3.0,
    'dns' => false
));

$connector->connect('tls://google.com:443')->then(function (ConnectionInterface $stream) {
    $stream->write("GET / HTTP/1.1\r\nHost: google.com\r\nConnection: close\r\n\r\n");
    $stream->on('data', function ($chunk) {
        echo $chunk;
    });
}, 'printf');

$loop->run();

See also the examples.

Usage

ProxyConnector

The ProxyConnector is responsible for creating plain TCP/IP connections to any destination by using an intermediary HTTP CONNECT proxy.

[you] -> [proxy] -> [destination]

Its constructor simply accepts an HTTP proxy URL and a connector used to connect to the proxy server address:

$connector = new Connector($loop);
$proxy = new ProxyConnector('http://127.0.0.1:8080', $connector);

The proxy URL may or may not contain a scheme and port definition. The default port will be 80 for HTTP (or 443 for HTTPS), but many common HTTP proxy servers use custom ports (often the alternative HTTP port 8080). In its most simple form, the given connector will be a \React\Socket\Connector if you want to connect to a given IP address as above.

This is the main class in this package. Because it implements ReactPHP's standard ConnectorInterface, it can simply be used in place of a normal connector. Accordingly, it provides only a single public method, the connect() method. The connect(string $uri): PromiseInterface<ConnectionInterface, Exception> method can be used to establish a streaming connection. It returns a Promise which either fulfills with a ConnectionInterface on success or rejects with an Exception on error.

This makes it fairly simple to add HTTP CONNECT proxy support to pretty much any higher-level component:

- $client = new SomeClient($connector);
+ $proxy = new ProxyConnector('http://127.0.0.1:8080', $connector);
+ $client = new SomeClient($proxy);

Plain TCP connections

HTTP CONNECT proxies are most frequently used to issue HTTPS requests to your destination. However, this is actually performed on a higher protocol layer and this connector is actually inherently a general-purpose plain TCP/IP connector. As documented above, you can simply invoke its connect() method to establish a streaming plain TCP/IP connection and use any higher level protocol like so:

$proxy = new ProxyConnector('http://127.0.0.1:8080', $connector);

$proxy->connect('tcp://smtp.googlemail.com:587')->then(function (ConnectionInterface $stream) {
    $stream->write("EHLO local\r\n");
    $stream->on('data', function ($chunk) use ($stream) {
        echo $chunk;
    });
});

You can either use the ProxyConnector directly or you may want to wrap this connector in ReactPHP's Connector:

$connector = new Connector($loop, array(
    'tcp' => $proxy,
    'dns' => false
));

$connector->connect('tcp://smtp.googlemail.com:587')->then(function (ConnectionInterface $stream) {
    $stream->write("EHLO local\r\n");
    $stream->on('data', function ($chunk) use ($stream) {
        echo $chunk;
    });
});

Note that HTTP CONNECT proxies often restrict which ports one may connect to. Many (public) proxy servers do in fact limit this to HTTPS (443) only.

Secure TLS connections

This class can also be used if you want to establish a secure TLS connection (formerly known as SSL) between you and your destination, such as when using secure HTTPS to your destination site. You can simply wrap this connector in ReactPHP's Connector or the low-level SecureConnector:

$proxy = new ProxyConnector('http://127.0.0.1:8080', $connector);
$connector = new Connector($loop, array(
    'tcp' => $proxy,
    'dns' => false
));

$connector->connect('tls://smtp.googlemail.com:465')->then(function (ConnectionInterface $stream) {
    $stream->write("EHLO local\r\n");
    $stream->on('data', function ($chunk) use ($stream) {
        echo $chunk;
    });
});

Note how secure TLS connections are in fact entirely handled outside of this HTTP CONNECT client implementation.

HTTP requests

HTTP operates on a higher layer than this low-level HTTP CONNECT implementation. If you want to issue HTTP requests, you can add a dependency for clue/reactphp-buzz. It can interact with this library by issuing all HTTP requests through a HTTP CONNECT proxy server. This works for both plain HTTP and TLS-encrypted HTTPS requests.

Connection timeout

By default, the ProxyConnector does not implement any timeouts for establishing remote connections. Your underlying operating system may impose limits on pending and/or idle TCP/IP connections, anywhere in a range of a few minutes to several hours.

Many use cases require more control over the timeout and likely values much smaller, usually in the range of a few seconds only.

You can use ReactPHP's Connector or the low-level TimeoutConnector to decorate any given ConnectorInterface instance. It provides the same connect() method, but will automatically reject the underlying connection attempt if it takes too long:

$connector = new Connector($loop, array(
    'tcp' => $proxy,
    'dns' => false,
    'timeout' => 3.0
));

$connector->connect('tcp://google.com:80')->then(function ($stream) {
    // connection succeeded within 3.0 seconds
});

See also any of the examples.

Note how the connection timeout is in fact entirely handled outside of this HTTP CONNECT client implementation.

DNS resolution

By default, the ProxyConnector does not perform any DNS resolution at all and simply forwards any hostname you're trying to connect to the remote proxy server. The remote proxy server is thus responsible for looking up any hostnames via DNS (this default mode is thus called remote DNS resolution).

As an alternative, you can also send the destination IP to the remote proxy server. In this mode you either have to stick to using IPs only (which is ofen unfeasable) or perform any DNS lookups locally and only transmit the resolved destination IPs (this mode is thus called local DNS resolution).

The default remote DNS resolution is useful if your local ProxyConnector either can not resolve target hostnames because it has no direct access to the internet or if it should not resolve target hostnames because its outgoing DNS traffic might be intercepted.

As noted above, the ProxyConnector defaults to using remote DNS resolution. However, wrapping the ProxyConnector in ReactPHP's Connector actually performs local DNS resolution unless explicitly defined otherwise. Given that remote DNS resolution is assumed to be the preferred mode, all other examples explicitly disable DNS resolution like this:

$connector = new Connector($loop, array(
    'tcp' => $proxy,
    'dns' => false
));

If you want to explicitly use local DNS resolution, you can use the following code:

// set up Connector which uses Google's public DNS (8.8.8.8)
$connector = new Connector($loop, array(
    'tcp' => $proxy,
    'dns' => '8.8.8.8'
));

Note how local DNS resolution is in fact entirely handled outside of this HTTP CONNECT client implementation.

Authentication

If your HTTP proxy server requires authentication, you may pass the username and password as part of the HTTP proxy URL like this:

$proxy = new ProxyConnector('http://user:pass@127.0.0.1:8080', $connector);

Note that both the username and password must be percent-encoded if they contain special characters:

$user = 'he:llo';
$pass = 'p@ss';

$proxy = new ProxyConnector(
    rawurlencode($user) . ':' . rawurlencode($pass) . '@127.0.0.1:8080',
    $connector
);

The authentication details will be used for basic authentication and will be transferred in the Proxy-Authorization HTTP request header for each connection attempt. If the authentication details are missing or not accepted by the remote HTTP proxy server, it is expected to reject each connection attempt with a 407 (Proxy Authentication Required) response status code and an exception error code of SOCKET_EACCES (13).

Advanced HTTP headers

The ProxyConnector constructor accepts an optional array of custom request headers to send in the CONNECT request. This can be useful if you're using a custom proxy setup or authentication scheme if the proxy server does not support basic authentication as documented above. This is rarely used in practice, but may be useful for some more advanced use cases. In this case, you may simply pass an assoc array of additional request headers like this:

$proxy = new ProxyConnector('127.0.0.1:8080', $connector, array(
    'Proxy-Authorization' =>  'Bearer abc123',
    'User-Agent' => 'ReactPHP'
));

Advanced secure proxy connections

Note that communication between the client and the proxy is usually via an unencrypted, plain TCP/IP HTTP connection. Note that this is the most common setup, because you can still establish a TLS connection between you and the destination host as above.

If you want to connect to a (rather rare) HTTPS proxy, you may want use the https:// scheme (HTTPS default port 443) and use ReactPHP's Connector or the low-level SecureConnector instance to create a secure connection to the proxy:

$connector = new Connector($loop);
$proxy = new ProxyConnector('https://127.0.0.1:443', $connector);

$proxy->connect('tcp://smtp.googlemail.com:587');

Advanced Unix domain sockets

HTTP CONNECT proxy servers support forwarding TCP/IP based connections and higher level protocols. In some advanced cases, it may be useful to let your HTTP CONNECT proxy server listen on a Unix domain socket (UDS) path instead of a IP:port combination. For example, this allows you to rely on file system permissions instead of having to rely on explicit authentication.

You can simply use the http+unix:// URI scheme like this:

$proxy = new ProxyConnector('http+unix:///tmp/proxy.sock', $connector);

$proxy->connect('tcp://google.com:80')->then(function (ConnectionInterface $stream) {
    // connected…
});

Similarly, you can also combine this with authentication like this:

$proxy = new ProxyConnector('http+unix://user:pass@/tmp/proxy.sock', $connector);

Note that Unix domain sockets (UDS) are considered advanced usage and PHP only has limited support for this. In particular, enabling secure TLS may not be supported.

Note that the HTTP CONNECT protocol does not support the notion of UDS paths. The above works reasonably well because UDS is only used for the connection between client and proxy server and the path will not actually passed over the protocol. This implies that this does not support connecting to UDS destination paths.

Install

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

This project follows SemVer. This will install the latest supported version:

$ composer require clue/http-proxy-react:^1.4

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

The test suite contains tests that rely on a working internet connection, alternatively you can also run it like this:

$ php vendor/bin/phpunit --exclude-group internet

License

This project is released under the permissive MIT license.

Did you know that I offer custom development services and issuing invoices for sponsorships of releases and for contributions? Contact me (@clue) for details.

More

  • If you want to learn more about how the ConnectorInterface and its usual implementations look like, refer to the documentation of the underlying react/socket component.
  • If you want to learn more about processing streams of data, refer to the documentation of the underlying react/stream component.
  • As an alternative to an HTTP CONNECT proxy, you may also want to look into using a SOCKS (SOCKS4/SOCKS5) proxy instead. You may want to use clue/reactphp-socks which also provides an implementation of the same ConnectorInterface so that supporting either proxy protocol should be fairly trivial.
  • If you're dealing with public proxies, you'll likely have to work with mixed quality and unreliable proxies. You may want to look into using clue/reactphp-connection-manager-extra which allows retrying unreliable ones, implying connection timeouts, concurrently working with multiple connectors and more.
  • If you're looking for an end-user HTTP CONNECT proxy server daemon, you may want to use LeProxy.