phptek / silverstripe-verifiable

src/Backend/Chainpoint/Gateway.php

<?php

/**
 * @author  Russell Michell 2018 <russ@theruss.com>
 * @package silverstripe-verifiable
 */

namespace PhpTek\Verifiable\Backend\Chainpoint;

use SilverStripe\Core\Config\Configurable;
use GuzzleHttp\Client;
use GuzzleHttp\Exception\RequestException;
use PhpTek\Verifiable\Exception\VerifiableBackendException;
use PhpTek\Verifiable\Exception\VerifiableValidationException;
use PhpTek\Verifiable\Backend\GatewayProvider;

/**
 * Calls the endpoints of the Tierion network's ChainPoint service.
 *
 * @see https://app.swaggerhub.com/apis/chainpoint/node/1.0.0
 * @see https://chainpoint.org
 */
class Gateway implements GatewayProvider
{
    use Configurable;

    /**
     * An array of nodes for submitting hashes to.
     *
     * @var array
     */
    protected static $discovered_nodes = [];

    /**
     * @return string
     */
    public function name() : string
    {
        return 'chainpoint';
    }

    /**
     * @return string
     */
    public function hashFunc() : string
    {
        return 'sha256';
    }

    /**
     * Send a single hash_id_node to retrieve a proof in binary format from the
     * Tierion network.
     *
     * GETs to the: "/proofs" REST API endpoint.
     *
     * @param  string $hashIdNode
     * @return string A v3 ChainpointProof
     */
    public function proofs(string $hashIdNode) : string
    {
        $response = $this->client("/proofs/$hashIdNode", 'GET');

        return $response->getBody()->getContents() ?? '[]';
    }

    /**
     * Send an array of hashes for anchoring.
     *
     * POSTs to the: "/hashes" REST API endpoint.
     *
     * @param  array $hashes
     * @return string (From GuzzleHttp\Stream::getContents()
     */
    public function hashes(array $hashes) : string
    {
        $response = $this->client('/hashes', 'POST', ['hashes' => $hashes]);

        return $response->getBody()->getContents() ?? '[]';
    }

    /**
     * Submit a chainpoint proof to the backend for verification.
     *
     * @param  string $proof A partial or full JSON string, originally received from,
     *                       or generated on behalf of a backend.
     * @return string
     * @todo See the returned proof's "uris" key, to be able to call a specific URI for proof verification.
     */
    public function verify(string $proof) : string
    {
        $response = $this->client('/verify', 'POST', ['proofs' => [$proof]]);

        return $response->getBody()->getContents() ?? '[]';
    }

    /**
     * Return a client to use for all RPC traffic to this backend.
     *
     * @param  string   $url     The absolute or relative URL to make a request to.
     * @param  string   $verb    The HTTP verb to use e.g. GET or POST.
     * @param  array    $payload The payload to be sent along in GET/POST requests.
     * @param  bool     $rel     Is $url relative? If so, pass "base_uri" to {@link Client}.
     * @return Response Guzzle   Response object

The type PhpTek\Verifiable\Backend\Chainpoint\Response was not found. Maybe you did not declare it correctly or list all dependencies?

     * @throws VerifiableBackendException
     */
    protected function client(string $url, string $verb, array $payload = [], bool $rel = true)
    {
        if ($rel && !$this->getDiscoveredNodes()) {
            $this->setDiscoveredNodes();

            if (!$this->getDiscoveredNodes()) {
                // This should _never_ happen..
                throw new VerifiableValidationException('No chainpoint nodes discovered!');
            }
        }

        $verb = strtoupper($verb);
        $method = strtolower($verb);
        $config = $this->config()->get('client_config');
        $client = new Client([
            'base_uri' => $rel ? $this->getDiscoveredNodes()[0] : '', // Use a single address only
            'verify' => true,
            'timeout'  => $config['timeout'],
            'connect_timeout'  => $config['connect_timeout'],
            'allow_redirects' => false,
        ]);

        try {
            // json_encodes POSTed data and sends correct Content-Type header
            if ($payload && $verb === 'POST') {

The expression $payload of type array is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

                $payload['json'] = $payload;
            }

            if ($rel) {
                $url = ($rel ? $this->getDiscoveredNodes()[0] : '')  . $url;

The condition $rel is always true.

            }

            return $client->$method($url, $payload);
        } catch (RequestException $e) {
            throw new VerifiableValidationException(sprintf('Upstream network problem: %s', $e->getMessage()));
        }
    }

    /**
     * The Tierion network comprises many nodes, some of which may or may not be
     * online. We therefore randomly select a source of curated (audited) node-IPs
     * and for each IP, we ping it until we receive a 200 OK response. For each such
     * node, it is then set to $discovered_nodes.
     *
     * @param  array $usedNodes  Optionally pass some "pre-known" chainpoint nodes
     * @return mixed void | null
     * @throws VerifiableBackendException
     */
    public function setDiscoveredNodes($usedNodes = null)
    {
        if ($usedNodes) {
            static::$discovered_nodes = $usedNodes;

            return;
        }

        if (count(static::$discovered_nodes)) {
            return;
        }

        $limit = (int) $this->config()->get('discover_node_count') ?: 1;
        $chainpointUrls = $this->config()->get('chainpoint_urls');
        $url = $chainpointUrls[rand(0, 2)];
        $response = $this->client($url, 'GET', [], false);

        if ($response->getStatusCode() !== 200) {
            throw new VerifiableBackendException('Bad response from node source URL');
        }

        $i = 0;

        foreach (json_decode($response->getBody(), true) as $candidate) {
            $response = $this->client($candidate['public_uri'], 'GET', [], false);

            if ($response->getStatusCode() !== 200) {
                continue;
            }

            ++$i; // Only increment with succesful requests

            static::$discovered_nodes[] = $candidate['public_uri'];

            if ($i === $limit) {
                break;
            }
        }
    }

    /**
     * @return array
     */
    public function getDiscoveredNodes()
    {
        return static::$discovered_nodes;
    }
}