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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.Immutable;
31  import org.apache.http.util.Args;
32  
33  /**
34   * Basic {@link HttpRouteDirector} implementation.
35   *
36   * @since 4.0
37   */
38  @Immutable
39  public class BasicRouteDirector implements HttpRouteDirector {
40  
41      /**
42       * Provides the next step.
43       *
44       * @param plan      the planned route
45       * @param fact      the currently established route, or
46       *                  <code>null</code> if nothing is established
47       *
48       * @return  one of the constants defined in this class, indicating
49       *          either the next step to perform, or success, or failure.
50       *          0 is for success, a negative value for failure.
51       */
52      public int nextStep(final RouteInfo plan, final RouteInfo fact) {
53          Args.notNull(plan, "Planned route");
54  
55          int step = UNREACHABLE;
56  
57          if ((fact == null) || (fact.getHopCount() < 1)) {
58              step = firstStep(plan);
59          } else if (plan.getHopCount() > 1) {
60              step = proxiedStep(plan, fact);
61          } else {
62              step = directStep(plan, fact);
63          }
64  
65          return step;
66  
67      } // nextStep
68  
69  
70      /**
71       * Determines the first step to establish a route.
72       *
73       * @param plan      the planned route
74       *
75       * @return  the first step
76       */
77      protected int firstStep(final RouteInfo plan) {
78  
79          return (plan.getHopCount() > 1) ?
80              CONNECT_PROXY : CONNECT_TARGET;
81      }
82  
83  
84      /**
85       * Determines the next step to establish a direct connection.
86       *
87       * @param plan      the planned route
88       * @param fact      the currently established route
89       *
90       * @return  one of the constants defined in this class, indicating
91       *          either the next step to perform, or success, or failure
92       */
93      protected int directStep(final RouteInfo plan, final RouteInfo fact) {
94  
95          if (fact.getHopCount() > 1) {
96              return UNREACHABLE;
97          }
98          if (!plan.getTargetHost().equals(fact.getTargetHost()))
99           {
100             return UNREACHABLE;
101         // If the security is too low, we could now suggest to layer
102         // a secure protocol on the direct connection. Layering on direct
103         // connections has not been supported in HttpClient 3.x, we don't
104         // consider it here until there is a real-life use case for it.
105         }
106 
107         // Should we tolerate if security is better than planned?
108         // (plan.isSecure() && !fact.isSecure())
109         if (plan.isSecure() != fact.isSecure()) {
110             return UNREACHABLE;
111         }
112 
113         // Local address has to match only if the plan specifies one.
114         if ((plan.getLocalAddress() != null) &&
115             !plan.getLocalAddress().equals(fact.getLocalAddress())
116             ) {
117             return UNREACHABLE;
118         }
119 
120         return COMPLETE;
121     }
122 
123 
124     /**
125      * Determines the next step to establish a connection via proxy.
126      *
127      * @param plan      the planned route
128      * @param fact      the currently established route
129      *
130      * @return  one of the constants defined in this class, indicating
131      *          either the next step to perform, or success, or failure
132      */
133     protected int proxiedStep(final RouteInfo plan, final RouteInfo fact) {
134 
135         if (fact.getHopCount() <= 1) {
136             return UNREACHABLE;
137         }
138         if (!plan.getTargetHost().equals(fact.getTargetHost())) {
139             return UNREACHABLE;
140         }
141         final int phc = plan.getHopCount();
142         final int fhc = fact.getHopCount();
143         if (phc < fhc) {
144             return UNREACHABLE;
145         }
146 
147         for (int i=0; i<fhc-1; i++) {
148             if (!plan.getHopTarget(i).equals(fact.getHopTarget(i))) {
149                 return UNREACHABLE;
150             }
151         }
152         // now we know that the target matches and proxies so far are the same
153         if (phc > fhc)
154          {
155             return TUNNEL_PROXY; // need to extend the proxy chain
156         }
157 
158         // proxy chain and target are the same, check tunnelling and layering
159         if ((fact.isTunnelled() && !plan.isTunnelled()) ||
160             (fact.isLayered()   && !plan.isLayered())) {
161             return UNREACHABLE;
162         }
163 
164         if (plan.isTunnelled() && !fact.isTunnelled()) {
165             return TUNNEL_TARGET;
166         }
167         if (plan.isLayered() && !fact.isLayered()) {
168             return LAYER_PROTOCOL;
169         }
170 
171         // tunnel and layering are the same, remains to check the security
172         // Should we tolerate if security is better than planned?
173         // (plan.isSecure() && !fact.isSecure())
174         if (plan.isSecure() != fact.isSecure()) {
175             return UNREACHABLE;
176         }
177 
178         return COMPLETE;
179     }
180 
181 }