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1   /*
2    * Copyright 2022 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   https://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.ssl.ocsp;
17  
18  import io.netty.channel.ChannelHandlerContext;
19  import io.netty.channel.ChannelInboundHandlerAdapter;
20  import io.netty.handler.ssl.SslHandler;
21  import io.netty.handler.ssl.SslHandshakeCompletionEvent;
22  import io.netty.resolver.dns.DnsNameResolver;
23  import io.netty.resolver.dns.DnsNameResolverBuilder;
24  import io.netty.util.AttributeKey;
25  import io.netty.util.concurrent.Future;
26  import io.netty.util.concurrent.GenericFutureListener;
27  import io.netty.util.concurrent.Promise;
28  import org.bouncycastle.cert.ocsp.BasicOCSPResp;
29  import org.bouncycastle.cert.ocsp.OCSPException;
30  import org.bouncycastle.cert.ocsp.RevokedStatus;
31  import org.bouncycastle.cert.ocsp.SingleResp;
32  
33  import java.security.cert.Certificate;
34  import java.security.cert.X509Certificate;
35  import java.util.Date;
36  
37  import static io.netty.util.internal.ObjectUtil.checkNotNull;
38  
39  /**
40   * {@link OcspServerCertificateValidator} validates incoming server's certificate
41   * using OCSP. Once TLS handshake is completed, {@link SslHandshakeCompletionEvent#SUCCESS} is fired, validator
42   * will perform certificate validation using OCSP over HTTP/1.1 with the server's certificate issuer OCSP responder.
43   */
44  public class OcspServerCertificateValidator extends ChannelInboundHandlerAdapter {
45      /**
46       * An attribute used to mark all channels created by the {@link OcspServerCertificateValidator}.
47       */
48      public static final AttributeKey<Boolean> OCSP_PIPELINE_ATTRIBUTE =
49              AttributeKey.newInstance("io.netty.handler.ssl.ocsp.pipeline");
50  
51      private final boolean closeAndThrowIfNotValid;
52      private final boolean validateNonce;
53      private final IoTransport ioTransport;
54      private final DnsNameResolver dnsNameResolver;
55  
56      /**
57       * Create a new {@link OcspServerCertificateValidator} instance without nonce validation
58       * on OCSP response, using default {@link IoTransport#DEFAULT} instance,
59       * default {@link DnsNameResolver} implementation and with {@link #closeAndThrowIfNotValid}
60       * set to {@code true}
61       */
62      public OcspServerCertificateValidator() {
63          this(false);
64      }
65  
66      /**
67       * Create a new {@link OcspServerCertificateValidator} instance with
68       * default {@link IoTransport#DEFAULT} instance and default {@link DnsNameResolver} implementation
69       * and {@link #closeAndThrowIfNotValid} set to {@code true}.
70       *
71       * @param validateNonce Set to {@code true} if we should force nonce validation on
72       *                      OCSP response else set to {@code false}
73       */
74      public OcspServerCertificateValidator(boolean validateNonce) {
75          this(validateNonce, IoTransport.DEFAULT);
76      }
77  
78      /**
79       * Create a new {@link OcspServerCertificateValidator} instance
80       *
81       * @param validateNonce Set to {@code true} if we should force nonce validation on
82       *                      OCSP response else set to {@code false}
83       * @param ioTransport   {@link IoTransport} to use
84       */
85      public OcspServerCertificateValidator(boolean validateNonce, IoTransport ioTransport) {
86          this(validateNonce, ioTransport, createDefaultResolver(ioTransport));
87      }
88  
89      /**
90       * Create a new {@link IoTransport} instance with {@link #closeAndThrowIfNotValid} set to {@code true}
91       *
92       * @param validateNonce   Set to {@code true} if we should force nonce validation on
93       *                        OCSP response else set to {@code false}
94       * @param ioTransport     {@link IoTransport} to use
95       * @param dnsNameResolver {@link DnsNameResolver} implementation to use
96       */
97      public OcspServerCertificateValidator(boolean validateNonce, IoTransport ioTransport,
98                                            DnsNameResolver dnsNameResolver) {
99          this(true, validateNonce, ioTransport, dnsNameResolver);
100     }
101 
102     /**
103      * Create a new {@link IoTransport} instance
104      *
105      * @param closeAndThrowIfNotValid If set to {@code true} then we will close the channel and throw an exception
106      *                                when certificate is not {@link OcspResponse.Status#VALID}.
107      *                                If set to {@code false} then we will simply pass the {@link OcspValidationEvent}
108      *                                to the next handler in pipeline and let it decide what to do.
109      * @param validateNonce           Set to {@code true} if we should force nonce validation on
110      *                                OCSP response else set to {@code false}
111      * @param ioTransport             {@link IoTransport} to use
112      * @param dnsNameResolver         {@link DnsNameResolver} implementation to use
113      */
114     public OcspServerCertificateValidator(boolean closeAndThrowIfNotValid, boolean validateNonce,
115                                           IoTransport ioTransport, DnsNameResolver dnsNameResolver) {
116         this.closeAndThrowIfNotValid = closeAndThrowIfNotValid;
117         this.validateNonce = validateNonce;
118         this.ioTransport = checkNotNull(ioTransport, "IoTransport");
119         this.dnsNameResolver = checkNotNull(dnsNameResolver, "DnsNameResolver");
120     }
121 
122     protected static DnsNameResolver createDefaultResolver(final IoTransport ioTransport) {
123         return new DnsNameResolverBuilder()
124                 .eventLoop(ioTransport.eventLoop())
125                 .channelFactory(ioTransport.datagramChannel())
126                 .socketChannelFactory(ioTransport.socketChannel())
127                 .build();
128     }
129 
130     @Override
131     public void userEventTriggered(final ChannelHandlerContext ctx, final Object evt) throws Exception {
132         ctx.fireUserEventTriggered(evt);
133 
134         if (evt instanceof SslHandshakeCompletionEvent) {
135             SslHandshakeCompletionEvent sslHandshakeCompletionEvent = (SslHandshakeCompletionEvent) evt;
136 
137             // If TLS handshake was successful then only we will perform OCSP certificate validation.
138             // If not, then just forward the event to next handler in pipeline and remove ourselves from pipeline.
139             if (sslHandshakeCompletionEvent.isSuccess()) {
140                 Certificate[] certificates = ctx.pipeline().get(SslHandler.class)
141                         .engine()
142                         .getSession()
143                         .getPeerCertificates();
144 
145                 assert certificates.length >= 2 : "There must an end-entity certificate and issuer certificate";
146 
147                 Promise<BasicOCSPResp> ocspRespPromise = OcspClient.query((X509Certificate) certificates[0],
148                         (X509Certificate) certificates[1], validateNonce, ioTransport, dnsNameResolver);
149 
150                 ocspRespPromise.addListener(new GenericFutureListener<Future<BasicOCSPResp>>() {
151                     @Override
152                     public void operationComplete(Future<BasicOCSPResp> future) throws Exception {
153                         // If Future is success then we have successfully received OCSP response
154                         // from OCSP responder. We will validate it now and process.
155                         if (future.isSuccess()) {
156                             SingleResp response = future.get().getResponses()[0];
157 
158                             Date current = new Date();
159                             if (!(current.after(response.getThisUpdate()) &&
160                                     current.before(response.getNextUpdate()))) {
161                                 ctx.fireExceptionCaught(new IllegalStateException("OCSP Response is out-of-date"));
162                             }
163 
164                             OcspResponse.Status status;
165                             if (response.getCertStatus() == null) {
166                                 // 'null' means certificate is valid
167                                 status = OcspResponse.Status.VALID;
168                             } else if (response.getCertStatus() instanceof RevokedStatus) {
169                                 status = OcspResponse.Status.REVOKED;
170                             } else {
171                                 status = OcspResponse.Status.UNKNOWN;
172                             }
173 
174                             ctx.fireUserEventTriggered(new OcspValidationEvent(
175                                     new OcspResponse(status, response.getThisUpdate(), response.getNextUpdate())));
176 
177                             // If Certificate is not VALID and 'closeAndThrowIfNotValid' is set
178                             // to 'true' then close the channel and throw an exception.
179                             if (status != OcspResponse.Status.VALID && closeAndThrowIfNotValid) {
180                                 ctx.channel().close();
181                                 // Certificate is not valid. Throw
182                                 ctx.fireExceptionCaught(new OCSPException(
183                                         "Certificate not valid. Status: " + status));
184                             }
185                         } else {
186                             ctx.fireExceptionCaught(future.cause());
187                         }
188                     }
189                 });
190             }
191             // Lets remove ourselves from the pipeline because we are done processing validation.
192             ctx.pipeline().remove(this);
193         }
194     }
195 
196     @Override
197     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
198         ctx.channel().close();
199     }
200 }