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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  
32  /**
33   * Basic implementation of an {@link HttpRouteDirector HttpRouteDirector}.
34   * This implementation is stateless and therefore thread-safe.
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(RouteInfo plan, RouteInfo fact) {
53          if (plan == null) {
54              throw new IllegalArgumentException
55                  ("Planned route may not be null.");
56          }
57  
58          int step = UNREACHABLE;
59  
60          if ((fact == null) || (fact.getHopCount() < 1))
61              step = firstStep(plan);
62          else if (plan.getHopCount() > 1)
63              step = proxiedStep(plan, fact);
64          else
65              step = directStep(plan, fact);
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(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(RouteInfo plan, RouteInfo fact) {
96  
97          if (fact.getHopCount() > 1)
98              return UNREACHABLE;
99          if (!plan.getTargetHost().equals(fact.getTargetHost()))
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         // Should we tolerate if security is better than planned?
107         // (plan.isSecure() && !fact.isSecure())
108         if (plan.isSecure() != fact.isSecure())
109             return UNREACHABLE;
110 
111         // Local address has to match only if the plan specifies one.
112         if ((plan.getLocalAddress() != null) &&
113             !plan.getLocalAddress().equals(fact.getLocalAddress())
114             )
115             return UNREACHABLE;
116 
117         return COMPLETE;
118     }
119 
120 
121     /**
122      * Determines the next step to establish a connection via proxy.
123      *
124      * @param plan      the planned route
125      * @param fact      the currently established route
126      *
127      * @return  one of the constants defined in this class, indicating
128      *          either the next step to perform, or success, or failure
129      */
130     protected int proxiedStep(RouteInfo plan, RouteInfo fact) {
131 
132         if (fact.getHopCount() <= 1)
133             return UNREACHABLE;
134         if (!plan.getTargetHost().equals(fact.getTargetHost()))
135             return UNREACHABLE;
136         final int phc = plan.getHopCount();
137         final int fhc = fact.getHopCount();
138         if (phc < fhc)
139             return UNREACHABLE;
140 
141         for (int i=0; i<fhc-1; i++) {
142             if (!plan.getHopTarget(i).equals(fact.getHopTarget(i)))
143                 return UNREACHABLE;
144         }
145         // now we know that the target matches and proxies so far are the same
146         if (phc > fhc)
147             return TUNNEL_PROXY; // need to extend the proxy chain
148 
149         // proxy chain and target are the same, check tunnelling and layering
150         if ((fact.isTunnelled() && !plan.isTunnelled()) ||
151             (fact.isLayered()   && !plan.isLayered()))
152             return UNREACHABLE;
153 
154         if (plan.isTunnelled() && !fact.isTunnelled())
155             return TUNNEL_TARGET;
156         if (plan.isLayered() && !fact.isLayered())
157             return LAYER_PROTOCOL;
158 
159         // tunnel and layering are the same, remains to check the security
160         // Should we tolerate if security is better than planned?
161         // (plan.isSecure() && !fact.isSecure())
162         if (plan.isSecure() != fact.isSecure())
163             return UNREACHABLE;
164 
165         return COMPLETE;
166     }
167 
168 }