001/*
002 * ====================================================================
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *   http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing,
014 * software distributed under the License is distributed on an
015 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
016 * KIND, either express or implied.  See the License for the
017 * specific language governing permissions and limitations
018 * under the License.
019 * ====================================================================
020 *
021 * This software consists of voluntary contributions made by many
022 * individuals on behalf of the Apache Software Foundation.  For more
023 * information on the Apache Software Foundation, please see
024 * <http://www.apache.org/>.
025 *
026 */
027
028package org.apache.http.conn.routing;
029
030import org.apache.http.annotation.Contract;
031import org.apache.http.annotation.ThreadingBehavior;
032import org.apache.http.util.Args;
033
034/**
035 * Basic {@link HttpRouteDirector} implementation.
036 *
037 * @since 4.0
038 */
039@Contract(threading = ThreadingBehavior.IMMUTABLE)
040public class BasicRouteDirector implements HttpRouteDirector {
041
042    /**
043     * Provides the next step.
044     *
045     * @param plan      the planned route
046     * @param fact      the currently established route, or
047     *                  {@code null} if nothing is established
048     *
049     * @return  one of the constants defined in this class, indicating
050     *          either the next step to perform, or success, or failure.
051     *          0 is for success, a negative value for failure.
052     */
053    @Override
054    public int nextStep(final RouteInfo plan, final RouteInfo fact) {
055        Args.notNull(plan, "Planned route");
056
057        int step = UNREACHABLE;
058
059        if ((fact == null) || (fact.getHopCount() < 1)) {
060            step = firstStep(plan);
061        } else if (plan.getHopCount() > 1) {
062            step = proxiedStep(plan, fact);
063        } else {
064            step = directStep(plan, fact);
065        }
066
067        return step;
068
069    } // nextStep
070
071
072    /**
073     * Determines the first step to establish a route.
074     *
075     * @param plan      the planned route
076     *
077     * @return  the first step
078     */
079    protected int firstStep(final RouteInfo plan) {
080
081        return (plan.getHopCount() > 1) ?
082            CONNECT_PROXY : CONNECT_TARGET;
083    }
084
085
086    /**
087     * Determines the next step to establish a direct connection.
088     *
089     * @param plan      the planned route
090     * @param fact      the currently established route
091     *
092     * @return  one of the constants defined in this class, indicating
093     *          either the next step to perform, or success, or failure
094     */
095    protected int directStep(final RouteInfo plan, final RouteInfo fact) {
096
097        if (fact.getHopCount() > 1) {
098            return UNREACHABLE;
099        }
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}