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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  
28  package org.apache.http.conn.routing;
29  
30  import org.apache.http.annotation.Contract;
31  import org.apache.http.annotation.ThreadingBehavior;
32  import org.apache.http.util.Args;
33  
34  /**
35   * Basic {@link HttpRouteDirector} implementation.
36   *
37   * @since 4.0
38   */
39  @Contract(threading = ThreadingBehavior.IMMUTABLE)
40  public class BasicRouteDirector implements HttpRouteDirector {
41  
42      /**
43       * Provides the next step.
44       *
45       * @param plan      the planned route
46       * @param fact      the currently established route, or
47       *                  {@code null} if nothing is established
48       *
49       * @return  one of the constants defined in this class, indicating
50       *          either the next step to perform, or success, or failure.
51       *          0 is for success, a negative value for failure.
52       */
53      @Override
54      public int nextStep(final RouteInfo plan, final RouteInfo fact) {
55          Args.notNull(plan, "Planned route");
56  
57          int step = UNREACHABLE;
58  
59          if ((fact == null) || (fact.getHopCount() < 1)) {
60              step = firstStep(plan);
61          } else if (plan.getHopCount() > 1) {
62              step = proxiedStep(plan, fact);
63          } else {
64              step = directStep(plan, fact);
65          }
66  
67          return step;
68  
69      } // nextStep
70  
71  
72      /**
73       * Determines the first step to establish a route.
74       *
75       * @param plan      the planned route
76       *
77       * @return  the first step
78       */
79      protected int firstStep(final RouteInfo plan) {
80  
81          return (plan.getHopCount() > 1) ?
82              CONNECT_PROXY : CONNECT_TARGET;
83      }
84  
85  
86      /**
87       * Determines the next step to establish a direct connection.
88       *
89       * @param plan      the planned route
90       * @param fact      the currently established route
91       *
92       * @return  one of the constants defined in this class, indicating
93       *          either the next step to perform, or success, or failure
94       */
95      protected int directStep(final RouteInfo plan, final RouteInfo fact) {
96  
97          if (fact.getHopCount() > 1) {
98              return UNREACHABLE;
99          }
100         if (!plan.getTargetHost().equals(fact.getTargetHost()))
101          {
102             return UNREACHABLE;
103         // If the security is too low, we could now suggest to layer
104         // a secure protocol on the direct connection. Layering on direct
105         // connections has not been supported in HttpClient 3.x, we don't
106         // consider it here until there is a real-life use case for it.
107         }
108 
109         // Should we tolerate if security is better than planned?
110         // (plan.isSecure() && !fact.isSecure())
111         if (plan.isSecure() != fact.isSecure()) {
112             return UNREACHABLE;
113         }
114 
115         // Local address has to match only if the plan specifies one.
116         if ((plan.getLocalAddress() != null) &&
117             !plan.getLocalAddress().equals(fact.getLocalAddress())
118             ) {
119             return UNREACHABLE;
120         }
121 
122         return COMPLETE;
123     }
124 
125 
126     /**
127      * Determines the next step to establish a connection via proxy.
128      *
129      * @param plan      the planned route
130      * @param fact      the currently established route
131      *
132      * @return  one of the constants defined in this class, indicating
133      *          either the next step to perform, or success, or failure
134      */
135     protected int proxiedStep(final RouteInfo plan, final RouteInfo fact) {
136 
137         if (fact.getHopCount() <= 1) {
138             return UNREACHABLE;
139         }
140         if (!plan.getTargetHost().equals(fact.getTargetHost())) {
141             return UNREACHABLE;
142         }
143         final int phc = plan.getHopCount();
144         final int fhc = fact.getHopCount();
145         if (phc < fhc) {
146             return UNREACHABLE;
147         }
148 
149         for (int i=0; i<fhc-1; i++) {
150             if (!plan.getHopTarget(i).equals(fact.getHopTarget(i))) {
151                 return UNREACHABLE;
152             }
153         }
154         // now we know that the target matches and proxies so far are the same
155         if (phc > fhc)
156          {
157             return TUNNEL_PROXY; // need to extend the proxy chain
158         }
159 
160         // proxy chain and target are the same, check tunnelling and layering
161         if ((fact.isTunnelled() && !plan.isTunnelled()) ||
162             (fact.isLayered()   && !plan.isLayered())) {
163             return UNREACHABLE;
164         }
165 
166         if (plan.isTunnelled() && !fact.isTunnelled()) {
167             return TUNNEL_TARGET;
168         }
169         if (plan.isLayered() && !fact.isLayered()) {
170             return LAYER_PROTOCOL;
171         }
172 
173         // tunnel and layering are the same, remains to check the security
174         // Should we tolerate if security is better than planned?
175         // (plan.isSecure() && !fact.isSecure())
176         if (plan.isSecure() != fact.isSecure()) {
177             return UNREACHABLE;
178         }
179 
180         return COMPLETE;
181     }
182 
183 }