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      1 /*
      2  * Copyright (c) 2008-2009, Motorola, Inc.
      3  *
      4  * All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions are met:
      8  *
      9  * - Redistributions of source code must retain the above copyright notice,
     10  * this list of conditions and the following disclaimer.
     11  *
     12  * - Redistributions in binary form must reproduce the above copyright notice,
     13  * this list of conditions and the following disclaimer in the documentation
     14  * and/or other materials provided with the distribution.
     15  *
     16  * - Neither the name of the Motorola, Inc. nor the names of its contributors
     17  * may be used to endorse or promote products derived from this software
     18  * without specific prior written permission.
     19  *
     20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
     21  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     23  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
     24  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     30  * POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 package javax.obex;
     34 
     35 import java.io.IOException;
     36 
     37 import android.util.Log;
     38 
     39 /**
     40  * The <code>ObexSession</code> interface characterizes the term
     41  * "OBEX Connection" as defined in the IrDA Object Exchange Protocol v1.2, which
     42  * could be the server-side view of an OBEX connection, or the client-side view
     43  * of the same connection, which is established by server's accepting of a
     44  * client issued "CONNECT".
     45  * <P>
     46  * This interface serves as the common super class for
     47  * <CODE>ClientSession</CODE> and <CODE>ServerSession</CODE>.
     48  * @hide
     49  */
     50 public class ObexSession {
     51 
     52     private static final String TAG = "ObexSession";
     53     private static final boolean V = ObexHelper.VDBG;
     54 
     55     protected Authenticator mAuthenticator;
     56 
     57     protected byte[] mChallengeDigest;
     58 
     59     /**
     60      * Called when the server received an authentication challenge header. This
     61      * will cause the authenticator to handle the authentication challenge.
     62      * @param header the header with the authentication challenge
     63      * @return <code>true</code> if the last request should be resent;
     64      *         <code>false</code> if the last request should not be resent
     65      * @throws IOException
     66      */
     67     public boolean handleAuthChall(HeaderSet header) throws IOException {
     68         if (mAuthenticator == null) {
     69             return false;
     70         }
     71 
     72         /*
     73          * An authentication challenge is made up of one required and two
     74          * optional tag length value triplets. The tag 0x00 is required to be in
     75          * the authentication challenge and it represents the challenge digest
     76          * that was received. The tag 0x01 is the options tag. This tag tracks
     77          * if user ID is required and if full access will be granted. The tag
     78          * 0x02 is the realm, which provides a description of which user name
     79          * and password to use.
     80          */
     81         byte[] challenge = ObexHelper.getTagValue((byte)0x00, header.mAuthChall);
     82         byte[] option = ObexHelper.getTagValue((byte)0x01, header.mAuthChall);
     83         byte[] description = ObexHelper.getTagValue((byte)0x02, header.mAuthChall);
     84 
     85         String realm = null;
     86         if (description != null) {
     87             byte[] realmString = new byte[description.length - 1];
     88             System.arraycopy(description, 1, realmString, 0, realmString.length);
     89 
     90             switch (description[0] & 0xFF) {
     91 
     92                 case ObexHelper.OBEX_AUTH_REALM_CHARSET_ASCII:
     93                     // ASCII encoding
     94                     // Fall through
     95                 case ObexHelper.OBEX_AUTH_REALM_CHARSET_ISO_8859_1:
     96                     // ISO-8859-1 encoding
     97                     try {
     98                         realm = new String(realmString, "ISO8859_1");
     99                     } catch (Exception e) {
    100                         throw new IOException("Unsupported Encoding Scheme");
    101                     }
    102                     break;
    103 
    104                 case ObexHelper.OBEX_AUTH_REALM_CHARSET_UNICODE:
    105                     // UNICODE Encoding
    106                     realm = ObexHelper.convertToUnicode(realmString, false);
    107                     break;
    108 
    109                 default:
    110                     throw new IOException("Unsupported Encoding Scheme");
    111             }
    112         }
    113 
    114         boolean isUserIDRequired = false;
    115         boolean isFullAccess = true;
    116         if (option != null) {
    117             if ((option[0] & 0x01) != 0) {
    118                 isUserIDRequired = true;
    119             }
    120 
    121             if ((option[0] & 0x02) != 0) {
    122                 isFullAccess = false;
    123             }
    124         }
    125 
    126         PasswordAuthentication result = null;
    127         header.mAuthChall = null;
    128 
    129         try {
    130             result = mAuthenticator
    131                     .onAuthenticationChallenge(realm, isUserIDRequired, isFullAccess);
    132         } catch (Exception e) {
    133             if (V) Log.d(TAG, "Exception occured - returning false", e);
    134             return false;
    135         }
    136 
    137         /*
    138          * If no password is provided then we not resent the request
    139          */
    140         if (result == null) {
    141             return false;
    142         }
    143 
    144         byte[] password = result.getPassword();
    145         if (password == null) {
    146             return false;
    147         }
    148 
    149         byte[] userName = result.getUserName();
    150 
    151         /*
    152          * Create the authentication response header. It includes 1 required and
    153          * 2 option tag length value triples. The required triple has a tag of
    154          * 0x00 and is the response digest. The first optional tag is 0x01 and
    155          * represents the user ID. If no user ID is provided, then no user ID
    156          * will be sent. The second optional tag is 0x02 and is the challenge
    157          * that was received. This will always be sent
    158          */
    159         if (userName != null) {
    160             header.mAuthResp = new byte[38 + userName.length];
    161             header.mAuthResp[36] = (byte)0x01;
    162             header.mAuthResp[37] = (byte)userName.length;
    163             System.arraycopy(userName, 0, header.mAuthResp, 38, userName.length);
    164         } else {
    165             header.mAuthResp = new byte[36];
    166         }
    167 
    168         // Create the secret String
    169         byte[] digest = new byte[challenge.length + password.length + 1];
    170         System.arraycopy(challenge, 0, digest, 0, challenge.length);
    171         // Insert colon between challenge and password
    172         digest[challenge.length] = (byte)0x3A;
    173         System.arraycopy(password, 0, digest, challenge.length + 1, password.length);
    174 
    175         // Add the Response Digest
    176         header.mAuthResp[0] = (byte)0x00;
    177         header.mAuthResp[1] = (byte)0x10;
    178 
    179         System.arraycopy(ObexHelper.computeMd5Hash(digest), 0, header.mAuthResp, 2, 16);
    180 
    181         // Add the challenge
    182         header.mAuthResp[18] = (byte)0x02;
    183         header.mAuthResp[19] = (byte)0x10;
    184         System.arraycopy(challenge, 0, header.mAuthResp, 20, 16);
    185 
    186         return true;
    187     }
    188 
    189     /**
    190      * Called when the server received an authentication response header. This
    191      * will cause the authenticator to handle the authentication response.
    192      * @param authResp the authentication response
    193      * @return <code>true</code> if the response passed; <code>false</code> if
    194      *         the response failed
    195      */
    196     public boolean handleAuthResp(byte[] authResp) {
    197         if (mAuthenticator == null) {
    198             return false;
    199         }
    200         // get the correct password from the application
    201         byte[] correctPassword = mAuthenticator.onAuthenticationResponse(ObexHelper.getTagValue(
    202                 (byte)0x01, authResp));
    203         if (correctPassword == null) {
    204             return false;
    205         }
    206 
    207         byte[] temp = new byte[correctPassword.length + 16];
    208 
    209         System.arraycopy(mChallengeDigest, 0, temp, 0, 16);
    210         System.arraycopy(correctPassword, 0, temp, 16, correctPassword.length);
    211 
    212         byte[] correctResponse = ObexHelper.computeMd5Hash(temp);
    213         byte[] actualResponse = ObexHelper.getTagValue((byte)0x00, authResp);
    214 
    215         // compare the MD5 hash array .
    216         for (int i = 0; i < 16; i++) {
    217             if (correctResponse[i] != actualResponse[i]) {
    218                 return false;
    219             }
    220         }
    221 
    222         return true;
    223     }
    224 }
    225