PaypalIPN.php

<?php

class PaypalIPN
{

    /**
     * @var bool $use_sandbox     Indicates if the sandbox endpoint is used.
     */
    private $use_sandbox = false;
    /**
     * @var bool $use_local_certs Indicates if the local certificates are used.
     */
    private $use_local_certs = true;

    /** Production Postback URL */
    const VERIFY_URI = 'https://ipnpb.paypal.com/cgi-bin/webscr';
    /** Sandbox Postback URL */
    const SANDBOX_VERIFY_URI = 'https://ipnpb.sandbox.paypal.com/cgi-bin/webscr';


    /** Response from PayPal indicating validation was successful */
    const VALID = 'VERIFIED';
    /** Response from PayPal indicating validation failed */
    const INVALID = 'INVALID';


    /**
     * Sets the IPN verification to sandbox mode (for use when testing,
     * should not be enabled in production).
     * @return void
     */
    public function useSandbox()
    {
        $this->use_sandbox = true;
    }

    /**
     * Sets curl to use php curl's built in certs (may be required in some
     * environments).
     * @return void
     */
    public function usePHPCerts()
    {
        $this->use_local_certs = false;
    }


    /**
     * Determine endpoint to post the verification data to.
     * @return string
     */
    public function getPaypalUri()
    {
        if ($this->use_sandbox) {
            return self::SANDBOX_VERIFY_URI;
        } else {
            return self::VERIFY_URI;
        }
    }


    /**
     * Verification Function
     * Sends the incoming post data back to PayPal using the cURL library.
     *
     * @return array or false
     * @throws Exception
     */
    public function verifyIPN()
    {
        if ( ! count($_POST)) {
            throw new Exception("Missing POST Data");
        }

        $raw_post_data = file_get_contents('php://input');
        $raw_post_array = explode('&', $raw_post_data);
        $myPost = array();
        $magic_quotes_enabled = false;
        if (function_exists('get_magic_quotes_gpc') && get_magic_quotes_gpc() == 1) {
            $magic_quotes_enabled = true;
        }
        foreach ($raw_post_array as $keyval) {
            $keyval = explode('=', $keyval);
            if (count($keyval) == 2) {
                // Since we do not want the plus signs in the date and email strings to be encoded to a space, we use rawurldecode instead of urldecode
                if (($keyval[0] === 'payment_date' && substr_count($keyval[1], '+') === 1) || strpos(rawurldecode($keyval[1]), ' ') !== false || ($_POST["test_ipn"] == 1 && filter_var($keyval[1], FILTER_VALIDATE_EMAIL))) {
                    // Keep plus signs
                    $myPost[$keyval[0]] = rawurldecode($keyval[1]);
                } else {
                    // Convert plus signs to spaces
                    $myPost[$keyval[0]] = urldecode($keyval[1]);
                    if ($magic_quotes_enabled) {
                        $myPost[$keyval[0]] = stripslashes($myPost[$keyval[0]]);
                    }
                }
            }
        }

        // Build the body of the verification post request, adding the _notify-validate command.
        $req = 'cmd=_notify-validate';
        foreach ($myPost as $key => $value) {
            $value = rawurlencode($value);
            $req .= "&$key=$value";
        }

        // Post the data back to PayPal, using curl. Throw exceptions if errors occur.
        $ch = curl_init($this->getPaypalUri());
        curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
        curl_setopt($ch, CURLOPT_SSLVERSION, 6);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);

        // This is often required if the server is missing a global cert bundle, or is using an outdated one.
        if ($this->use_local_certs) {
            curl_setopt($ch, CURLOPT_CAINFO, __DIR__ . "/cert/cacert.pem");
        }
        curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
        curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: Close'));
        $res = curl_exec($ch);
        if ( ! ($res)) {
            $errno = curl_errno($ch);
            $errstr = curl_error($ch);
            curl_close($ch);
            throw new Exception("cURL error: [$errno] $errstr");
        }

        $info = curl_getinfo($ch);
        $http_code = $info['http_code'];
        if ($http_code != 200) {
            throw new Exception("PayPal responded with http code $http_code");
        }

        curl_close($ch);

        // Check if PayPal verifies the IPN data, and if so, return data array.
        if ($res == self::VALID) {
            return $myPost;
        }
        return false;
    }
}