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      1 /*
      2  * Copyright (C) 2013 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://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,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.exchange.eas;
     18 
     19 import com.android.exchange.Eas;
     20 import com.android.exchange.EasResponse;
     21 import com.android.mail.utils.LogUtils;
     22 import com.google.common.collect.Sets;
     23 
     24 import org.apache.http.Header;
     25 import org.apache.http.HttpEntity;
     26 import org.apache.http.client.methods.HttpUriRequest;
     27 
     28 import java.io.IOException;
     29 import java.util.HashSet;
     30 
     31 /**
     32  * Performs an HTTP Options request to the Exchange server, in order to get the protocol
     33  * version.
     34  */
     35 public class EasOptions extends EasOperation {
     36     private static final String LOG_TAG = Eas.LOG_TAG;
     37 
     38     /** Result code indicating we successfully got a protocol version. */
     39     public static final int RESULT_OK = 1;
     40 
     41     /** Set of Exchange protocol versions we understand. */
     42     private static final HashSet<String> SUPPORTED_PROTOCOL_VERSIONS = Sets.newHashSet(
     43             Eas.SUPPORTED_PROTOCOL_EX2003,
     44             Eas.SUPPORTED_PROTOCOL_EX2007, Eas.SUPPORTED_PROTOCOL_EX2007_SP1,
     45             Eas.SUPPORTED_PROTOCOL_EX2010, Eas.SUPPORTED_PROTOCOL_EX2010_SP1);
     46 
     47     private String mProtocolVersion = null;
     48 
     49     public EasOptions(final EasOperation parentOperation) {
     50         super(parentOperation);
     51     }
     52 
     53     /**
     54      * Perform the server request. If successful, callers should use
     55      * {@link #getProtocolVersionString} to get the actual protocol version value.
     56      * @return A result code; {@link #RESULT_OK} is the only value that indicates success.
     57      */
     58     public int getProtocolVersionFromServer() {
     59         return performOperation();
     60     }
     61 
     62     /**
     63      * @return The protocol version to use, or null if we did not successfully get one.
     64      */
     65     public String getProtocolVersionString() {
     66         return mProtocolVersion;
     67     }
     68 
     69     /**
     70      * Note that this operation does not actually use this name when forming the request.
     71      * @return A useful name for logging this operation.
     72      */
     73     @Override
     74     protected String getCommand() {
     75         return "OPTIONS";
     76     }
     77 
     78     @Override
     79     protected HttpEntity getRequestEntity() {
     80         return null;
     81     }
     82 
     83     @Override
     84     protected int handleResponse(final EasResponse response) {
     85         final Header commands = response.getHeader("MS-ASProtocolCommands");
     86         final Header versions = response.getHeader("ms-asprotocolversions");
     87         final boolean hasProtocolVersion;
     88         if (commands == null || versions == null) {
     89             LogUtils.e(LOG_TAG, "OPTIONS response without commands or versions");
     90             hasProtocolVersion = false;
     91         } else {
     92             mProtocolVersion = getProtocolVersionFromHeader(versions);
     93             hasProtocolVersion = (mProtocolVersion != null);
     94         }
     95         if (!hasProtocolVersion) {
     96             return RESULT_PROTOCOL_VERSION_UNSUPPORTED;
     97         }
     98 
     99         return RESULT_OK;
    100     }
    101 
    102     @Override
    103     protected String getRequestUri() {
    104         return null;
    105     }
    106 
    107     protected HttpUriRequest makeRequest() throws IOException, MessageInvalidException {
    108         return mConnection.makeOptions();
    109     }
    110     /**
    111      * Find the best protocol version to use from the header.
    112      * @param versionHeader The {@link Header} for the server's supported versions.
    113      * @return The best protocol version we mutually support, or null if none found.
    114      */
    115     private String getProtocolVersionFromHeader(final Header versionHeader) {
    116         // The string is a comma separated list of EAS versions in ascending order
    117         // e.g. 1.0,2.0,2.5,12.0,12.1,14.0,14.1
    118         final String supportedVersions = versionHeader.getValue();
    119         LogUtils.d(LOG_TAG, "Server supports versions: %s", supportedVersions);
    120         final String[] supportedVersionsArray = supportedVersions.split(",");
    121         // Find the most recent version we support
    122         String newProtocolVersion = null;
    123         for (final String version: supportedVersionsArray) {
    124             if (SUPPORTED_PROTOCOL_VERSIONS.contains(version)) {
    125                 newProtocolVersion = version;
    126             }
    127         }
    128         return newProtocolVersion;
    129     }
    130 }
    131