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 27 import java.util.HashSet; 28 29 /** 30 * Performs an HTTP Options request to the Exchange server, in order to get the protocol 31 * version. 32 */ 33 public class EasOptions extends EasOperation { 34 private static final String LOG_TAG = Eas.LOG_TAG; 35 36 /** Result code indicating we successfully got a protocol version. */ 37 public static final int RESULT_OK = 1; 38 39 /** Set of Exchange protocol versions we understand. */ 40 private static final HashSet<String> SUPPORTED_PROTOCOL_VERSIONS = Sets.newHashSet( 41 Eas.SUPPORTED_PROTOCOL_EX2003, 42 Eas.SUPPORTED_PROTOCOL_EX2007, Eas.SUPPORTED_PROTOCOL_EX2007_SP1, 43 Eas.SUPPORTED_PROTOCOL_EX2010, Eas.SUPPORTED_PROTOCOL_EX2010_SP1); 44 45 private String mProtocolVersion = null; 46 EasOptions(final EasOperation parentOperation)47 public EasOptions(final EasOperation parentOperation) { 48 super(parentOperation); 49 } 50 51 /** 52 * Perform the server request. If successful, callers should use 53 * {@link #getProtocolVersionString} to get the actual protocol version value. 54 * @return A result code; {@link #RESULT_OK} is the only value that indicates success. 55 */ getProtocolVersionFromServer()56 public int getProtocolVersionFromServer() { 57 return performOperation(); 58 } 59 60 /** 61 * @return The protocol version to use, or null if we did not successfully get one. 62 */ getProtocolVersionString()63 public String getProtocolVersionString() { 64 return mProtocolVersion; 65 } 66 67 /** 68 * Note that this operation does not actually use this name when forming the request. 69 * @return A useful name for logging this operation. 70 */ 71 @Override getCommand()72 protected String getCommand() { 73 return "OPTIONS"; 74 } 75 76 @Override getRequestEntity()77 protected HttpEntity getRequestEntity() { 78 return null; 79 } 80 81 @Override handleResponse(final EasResponse response)82 protected int handleResponse(final EasResponse response) { 83 final Header commands = response.getHeader("MS-ASProtocolCommands"); 84 final Header versions = response.getHeader("ms-asprotocolversions"); 85 final boolean hasProtocolVersion; 86 if (commands == null || versions == null) { 87 LogUtils.e(LOG_TAG, "OPTIONS response without commands or versions"); 88 hasProtocolVersion = false; 89 } else { 90 mProtocolVersion = getProtocolVersionFromHeader(versions); 91 hasProtocolVersion = (mProtocolVersion != null); 92 } 93 if (!hasProtocolVersion) { 94 return RESULT_PROTOCOL_VERSION_UNSUPPORTED; 95 } 96 97 return RESULT_OK; 98 } 99 100 @Override getRequestUri()101 protected String getRequestUri() { 102 return null; 103 } 104 105 /** 106 * Find the best protocol version to use from the header. 107 * @param versionHeader The {@link Header} for the server's supported versions. 108 * @return The best protocol version we mutually support, or null if none found. 109 */ getProtocolVersionFromHeader(final Header versionHeader)110 private String getProtocolVersionFromHeader(final Header versionHeader) { 111 // The string is a comma separated list of EAS versions in ascending order 112 // e.g. 1.0,2.0,2.5,12.0,12.1,14.0,14.1 113 final String supportedVersions = versionHeader.getValue(); 114 LogUtils.d(LOG_TAG, "Server supports versions: %s", supportedVersions); 115 final String[] supportedVersionsArray = supportedVersions.split(","); 116 // Find the most recent version we support 117 String newProtocolVersion = null; 118 for (final String version: supportedVersionsArray) { 119 if (SUPPORTED_PROTOCOL_VERSIONS.contains(version)) { 120 newProtocolVersion = version; 121 } 122 } 123 return newProtocolVersion; 124 } 125 } 126