Guzzle Message Integrity Subscriber

Verifies the integrity of HTTP responses using customizable validators.

This plugin can be used, for example, to validate the message integrity of responses based on the Content-MD5 header. The plugin offers a convenience method for validating a Content-MD5 header.

use GuzzleHttp\Client();
use GuzzleHttp\Subscriber\MessageIntegrity\ResponseIntegrity;

$subscriber = ResponseIntegrity::createForContentMd5();
$client = new Client();
$client->getEmitter()->attach($subscriber);

Installing

This project can be installed using Composer. Add the following to your composer.json:

{
    "require": {
        "guzzlehttp/message-integrity-subscriber": "0.1.0"
    }
}

Constructor Options

The GuzzleHttp\Subscriber\MessageIntegrity\ResponseIntegrity class accepts an associative array of options:

expected

(callable) A function that returns the hash that is expected for a response. The function accepts a ResponseInterface objects and returns a string that is compared against the calculated rolling hash.

hash

(GuzzleHttp\Subscriber\MessageIntegrity\HashInterface) A hash object used to compute a hash of the response body. The result created by the has is then compared against the extracted header value.

size_cutoff

(integer) If specified, the message integrity will only be validated if the response size is less than the size_cutoff value (in bytes).

use GuzzleHttp\Client();
use GuzzleHttp\Message\ResponseInterface;
use GuzzleHttp\Subscriber\MessageIntegrity\ResponseIntegrity;

$subscriber = new ResponseIntegrity([
    'hash' => new PhpHash('md5', ['base64' => true])
    'expected' => function (ResponseInterface $response) {
        return $response->getHeader('Content-MD5');
    }
]);

$client = new Client();
$client->getEmitter()->attach($subscriber);

Handling Errors

If the calculated hash of the response body does not match the extracted responses header, then a GuzzleHttp\Subscriber\MessageIntegrity\MessageIntegrityException is thrown. This exception extends from GuzzleHttp\Exception\RequestException so it contains a request accessed via getRequest() and a response via getResponse().

use GuzzleHttp\Client();
use GuzzleHttp\Subscriber\MessageIntegrity\ResponseIntegrity;
use GuzzleHttp\Subscriber\MessageIntegrity\MessageIntegrityException;

$subscriber = ResponseIntegrity::createForContentMd5();
$client = new Client();
$client->getEmitter()->attach($subscriber);

try {
    $client->get('http://httpbin.org/get');
} catch (MessageIntegrityException $e) {
    echo $e->getRequest() . "\n";
    echo $e->getResponse() . "\n";
}

Limitations

• Only works with seekable responses or streaming responses.
• Does not currently work with responses that use a Transfer-Encoding header.
• Does not currently work with responses that use a Content-Encoding header.