/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.security.provider.certpath;

import java.io.InputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.net.URI;

import java.net.URL;

import java.net.HttpURLConnection;

import java.security.cert.CertificateException;

import java.security.cert.CertPathValidatorException;

import java.security.cert.CRLReason;

import java.security.cert.Extension;

import java.security.cert.X509Certificate;

import java.util.Arrays;

import java.util.Collections;

import java.util.Date;

import java.util.List;

import java.util.Map;

import static sun.security.provider.certpath.OCSPResponse.*;

import sun.security.util.Debug;

import sun.security.x509.AccessDescription;

import sun.security.x509.AuthorityInfoAccessExtension;

import sun.security.x509.GeneralName;

import sun.security.x509.GeneralNameInterface;

import sun.security.x509.URIName;

import sun.security.x509.X509CertImpl;

/**

 * This is a class that checks the revocation status of a certificate(s) using

 * OCSP. It is not a PKIXCertPathChecker and therefore can be used outside of

 * the CertPathValidator framework. It is useful when you want to

 * just check the revocation status of a certificate, and you don't want to

 * incur the overhead of validating all of the certificates in the

 * associated certificate chain.

 *

 * @author Sean Mullan

 */

public final class OCSP {

    private static final Debug debug = Debug.getInstance("certpath");

    private static final int CONNECT_TIMEOUT = 15000; // 15 seconds

    private OCSP() {}

    /**

     * Obtains the revocation status of a certificate using OCSP using the most

     * common defaults. The OCSP responder URI is retrieved from the

     * certificate's AIA extension. The OCSP responder certificate is assumed

     * to be the issuer's certificate (or issued by the issuer CA).

     *

     * @param cert the certificate to be checked

     * @param issuerCert the issuer certificate

     * @return the RevocationStatus

     * @throws IOException if there is an exception connecting to or

     *    communicating with the OCSP responder

     * @throws CertPathValidatorException if an exception occurs while

     *    encoding the OCSP Request or validating the OCSP Response

     */

    public static RevocationStatus check(X509Certificate cert,

        X509Certificate issuerCert)

        throws IOException, CertPathValidatorException {

        CertId certId = null;

        URI responderURI = null;

        try {

            X509CertImpl certImpl = X509CertImpl.toImpl(cert);

            responderURI = getResponderURI(certImpl);

            if (responderURI == null) {

                throw new CertPathValidatorException

                    ("No OCSP Responder URI in certificate");

            }

            certId = new CertId(issuerCert, certImpl.getSerialNumberObject());

        } catch (CertificateException ce) {

            throw new CertPathValidatorException

                ("Exception while encoding OCSPRequest", ce);

        } catch (IOException ioe) {

            throw new CertPathValidatorException

                ("Exception while encoding OCSPRequest", ioe);

        }

        OCSPResponse ocspResponse = check(Collections.singletonList(certId),

            responderURI, issuerCert, null);

        return (RevocationStatus) ocspResponse.getSingleResponse(certId);

    }

    /**

     * Obtains the revocation status of a certificate using OCSP.

     *

     * @param cert the certificate to be checked

     * @param issuerCert the issuer certificate

     * @param responderURI the URI of the OCSP responder

     * @param responderCert the OCSP responder's certificate

     * @param date the time the validity of the OCSP responder's certificate

     *    should be checked against. If null, the current time is used.

     * @return the RevocationStatus

     * @throws IOException if there is an exception connecting to or

     *    communicating with the OCSP responder

     * @throws CertPathValidatorException if an exception occurs while

     *    encoding the OCSP Request or validating the OCSP Response

     */

    public static RevocationStatus check(X509Certificate cert,

        X509Certificate issuerCert, URI responderURI, X509Certificate

        responderCert, Date date)

        throws IOException, CertPathValidatorException {

        CertId certId = null;

        try {

            X509CertImpl certImpl = X509CertImpl.toImpl(cert);

            certId = new CertId(issuerCert, certImpl.getSerialNumberObject());

        } catch (CertificateException ce) {

            throw new CertPathValidatorException

                ("Exception while encoding OCSPRequest", ce);

        } catch (IOException ioe) {

            throw new CertPathValidatorException

                ("Exception while encoding OCSPRequest", ioe);

        }

        OCSPResponse ocspResponse = check(Collections.singletonList(certId),

            responderURI, responderCert, date);

        return (RevocationStatus) ocspResponse.getSingleResponse(certId);

    }

    /**

     * Checks the revocation status of a list of certificates using OCSP.

     *

     * @param certs the CertIds to be checked

     * @param responderURI the URI of the OCSP responder

     * @param responderCert the OCSP responder's certificate

     * @param date the time the validity of the OCSP responder's certificate

     *    should be checked against. If null, the current time is used.

     * @return the OCSPResponse

     * @throws IOException if there is an exception connecting to or

     *    communicating with the OCSP responder

     * @throws CertPathValidatorException if an exception occurs while

     *    encoding the OCSP Request or validating the OCSP Response

     */

    static OCSPResponse check(List<CertId> certIds, URI responderURI,

        X509Certificate responderCert, Date date)

        throws IOException, CertPathValidatorException {

        byte[] bytes = null;

        try {

            OCSPRequest request = new OCSPRequest(certIds);

            bytes = request.encodeBytes();

        } catch (IOException ioe) {

            throw new CertPathValidatorException

                ("Exception while encoding OCSPRequest", ioe);

        }

        InputStream in = null;

        OutputStream out = null;

        byte[] response = null;

        try {

            URL url = responderURI.toURL();

            if (debug != null) {

                debug.println("connecting to OCSP service at: " + url);

            }

            HttpURLConnection con = (HttpURLConnection)url.openConnection();

            con.setConnectTimeout(CONNECT_TIMEOUT);

            con.setReadTimeout(CONNECT_TIMEOUT);

            con.setDoOutput(true);

            con.setDoInput(true);

            con.setRequestMethod("POST");

            con.setRequestProperty

                ("Content-type", "application/ocsp-request");

            con.setRequestProperty

                ("Content-length", String.valueOf(bytes.length));

            out = con.getOutputStream();

            out.write(bytes);

            out.flush();

            // Check the response

            if (debug != null &&

                con.getResponseCode() != HttpURLConnection.HTTP_OK) {

                debug.println("Received HTTP error: " + con.getResponseCode()

                    + " - " + con.getResponseMessage());

            }

            in = con.getInputStream();

            int contentLength = con.getContentLength();

            if (contentLength == -1) {

                contentLength = Integer.MAX_VALUE;

            }

            response = new byte[contentLength > 2048 ? 2048 : contentLength];

            int total = 0;

            while (total < contentLength) {

                int count = in.read(response, total, response.length - total);

                if (count < 0)

                    break;

                total += count;

                if (total >= response.length && total < contentLength) {

                    response = Arrays.copyOf(response, total * 2);

                }

            }

            response = Arrays.copyOf(response, total);

        } finally {

            if (in != null) {

                try {

                    in.close();

                } catch (IOException ioe) {

                    throw ioe;

                }

            }

            if (out != null) {

                try {

                    out.close();

                } catch (IOException ioe) {

                    throw ioe;

                }

            }

        }

        OCSPResponse ocspResponse = null;

        try {

            ocspResponse = new OCSPResponse(response, date, responderCert);

        } catch (IOException ioe) {

            // response decoding exception

            throw new CertPathValidatorException(ioe);

        }

        if (ocspResponse.getResponseStatus() != ResponseStatus.SUCCESSFUL) {

            throw new CertPathValidatorException

                ("OCSP response error: " + ocspResponse.getResponseStatus());

        }

        // Check that the response includes a response for all of the

        // certs that were supplied in the request

        for (CertId certId : certIds) {

            SingleResponse sr = ocspResponse.getSingleResponse(certId);

            if (sr == null) {

                if (debug != null) {

                    debug.println("No response found for CertId: " + certId);

                }

                throw new CertPathValidatorException(

                    "OCSP response does not include a response for a " +

                    "certificate supplied in the OCSP request");

            }

            if (debug != null) {

                debug.println("Status of certificate (with serial number " +

                    certId.getSerialNumber() + ") is: " + sr.getCertStatus());

            }

        }

        return ocspResponse;

    }

    /**

     * Returns the URI of the OCSP Responder as specified in the

     * certificate's Authority Information Access extension, or null if

     * not specified.

     *

     * @param cert the certificate

     * @return the URI of the OCSP Responder, or null if not specified

     */

    public static URI getResponderURI(X509Certificate cert) {

        try {

            return getResponderURI(X509CertImpl.toImpl(cert));

        } catch (CertificateException ce) {

            // treat this case as if the cert had no extension

            return null;

        }

    }

    static URI getResponderURI(X509CertImpl certImpl) {

        // Examine the certificate's AuthorityInfoAccess extension

        AuthorityInfoAccessExtension aia =

            certImpl.getAuthorityInfoAccessExtension();

        if (aia == null) {

            return null;

        }

        List<AccessDescription> descriptions = aia.getAccessDescriptions();

        for (AccessDescription description : descriptions) {

                AccessDescription.Ad_OCSP_Id)) {

                GeneralName generalName = description.getAccessLocation();

                if (generalName.getType() == GeneralNameInterface.NAME_URI) {

                    URIName uri = (URIName) generalName.getName();

                    return uri.getURI();

                }

            }

        }

        return null;

    }

    /**

     * The Revocation Status of a certificate.

     */

    public static interface RevocationStatus {

        public enum CertStatus { GOOD, REVOKED, UNKNOWN };

        /**

         * Returns the revocation status.

         */

        CertStatus getCertStatus();

        /**

         * Returns the time when the certificate was revoked, or null

         * if it has not been revoked.

         */

        Date getRevocationTime();

        /**

         * Returns the reason the certificate was revoked, or null if it

         * has not been revoked.

         */

        CRLReason getRevocationReason();

        /**

         * Returns a Map of additional extensions.

         */

        Map<String, Extension> getSingleExtensions();

    }

}