michael@0: /*
michael@0:  * ====================================================================
michael@0:  *
michael@0:  *  Licensed to the Apache Software Foundation (ASF) under one or more
michael@0:  *  contributor license agreements.  See the NOTICE file distributed with
michael@0:  *  this work for additional information regarding copyright ownership.
michael@0:  *  The ASF licenses this file to You under the Apache License, Version 2.0
michael@0:  *  (the "License"); you may not use this file except in compliance with
michael@0:  *  the License.  You may obtain a copy of the License at
michael@0:  *
michael@0:  *      http://www.apache.org/licenses/LICENSE-2.0
michael@0:  *
michael@0:  *  Unless required by applicable law or agreed to in writing, software
michael@0:  *  distributed under the License is distributed on an "AS IS" BASIS,
michael@0:  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
michael@0:  *  See the License for the specific language governing permissions and
michael@0:  *  limitations under the License.
michael@0:  * ====================================================================
michael@0:  *
michael@0:  * This software consists of voluntary contributions made by many
michael@0:  * individuals on behalf of the Apache Software Foundation.  For more
michael@0:  * information on the Apache Software Foundation, please see
michael@0:  * <http://www.apache.org/>.
michael@0:  *
michael@0:  */
michael@0: 
michael@0: package ch.boye.httpclientandroidlib.impl.auth;
michael@0: 
michael@0: import java.security.MessageDigest;
michael@0: import java.security.SecureRandom;
michael@0: import java.util.ArrayList;
michael@0: import java.util.Formatter;
michael@0: import java.util.List;
michael@0: import java.util.Locale;
michael@0: import java.util.StringTokenizer;
michael@0: 
michael@0: import ch.boye.httpclientandroidlib.annotation.NotThreadSafe;
michael@0: 
michael@0: import ch.boye.httpclientandroidlib.Header;
michael@0: import ch.boye.httpclientandroidlib.HttpRequest;
michael@0: import ch.boye.httpclientandroidlib.auth.AuthenticationException;
michael@0: import ch.boye.httpclientandroidlib.auth.Credentials;
michael@0: import ch.boye.httpclientandroidlib.auth.AUTH;
michael@0: import ch.boye.httpclientandroidlib.auth.MalformedChallengeException;
michael@0: import ch.boye.httpclientandroidlib.auth.params.AuthParams;
michael@0: import ch.boye.httpclientandroidlib.message.BasicNameValuePair;
michael@0: import ch.boye.httpclientandroidlib.message.BasicHeaderValueFormatter;
michael@0: import ch.boye.httpclientandroidlib.message.BufferedHeader;
michael@0: import ch.boye.httpclientandroidlib.util.CharArrayBuffer;
michael@0: import ch.boye.httpclientandroidlib.util.EncodingUtils;
michael@0: 
michael@0: /**
michael@0:  * Digest authentication scheme as defined in RFC 2617.
michael@0:  * Both MD5 (default) and MD5-sess are supported.
michael@0:  * Currently only qop=auth or no qop is supported. qop=auth-int
michael@0:  * is unsupported. If auth and auth-int are provided, auth is
michael@0:  * used.
michael@0:  * <p>
michael@0:  * Credential charset is configured via the
michael@0:  * {@link ch.boye.httpclientandroidlib.auth.params.AuthPNames#CREDENTIAL_CHARSET}
michael@0:  * parameter of the HTTP request.
michael@0:  * <p>
michael@0:  * Since the digest username is included as clear text in the generated
michael@0:  * Authentication header, the charset of the username must be compatible
michael@0:  * with the
michael@0:  * {@link ch.boye.httpclientandroidlib.params.CoreProtocolPNames#HTTP_ELEMENT_CHARSET
michael@0:  *        http element charset}.
michael@0:  * <p>
michael@0:  * The following parameters can be used to customize the behavior of this
michael@0:  * class:
michael@0:  * <ul>
michael@0:  *  <li>{@link ch.boye.httpclientandroidlib.auth.params.AuthPNames#CREDENTIAL_CHARSET}</li>
michael@0:  * </ul>
michael@0:  *
michael@0:  * @since 4.0
michael@0:  */
michael@0: @NotThreadSafe
michael@0: public class DigestScheme extends RFC2617Scheme {
michael@0: 
michael@0:     /**
michael@0:      * Hexa values used when creating 32 character long digest in HTTP DigestScheme
michael@0:      * in case of authentication.
michael@0:      *
michael@0:      * @see #encode(byte[])
michael@0:      */
michael@0:     private static final char[] HEXADECIMAL = {
michael@0:         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
michael@0:         'e', 'f'
michael@0:     };
michael@0: 
michael@0:     /** Whether the digest authentication process is complete */
michael@0:     private boolean complete;
michael@0: 
michael@0:     private static final int QOP_UNKNOWN = -1;
michael@0:     private static final int QOP_MISSING = 0;
michael@0:     private static final int QOP_AUTH_INT = 1;
michael@0:     private static final int QOP_AUTH = 2;
michael@0: 
michael@0:     private String lastNonce;
michael@0:     private long nounceCount;
michael@0:     private String cnonce;
michael@0:     private String a1;
michael@0:     private String a2;
michael@0: 
michael@0:     /**
michael@0:      * Default constructor for the digest authetication scheme.
michael@0:      */
michael@0:     public DigestScheme() {
michael@0:         super();
michael@0:         this.complete = false;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Processes the Digest challenge.
michael@0:      *
michael@0:      * @param header the challenge header
michael@0:      *
michael@0:      * @throws MalformedChallengeException is thrown if the authentication challenge
michael@0:      * is malformed
michael@0:      */
michael@0:     @Override
michael@0:     public void processChallenge(
michael@0:             final Header header) throws MalformedChallengeException {
michael@0:         super.processChallenge(header);
michael@0: 
michael@0:         if (getParameter("realm") == null) {
michael@0:             throw new MalformedChallengeException("missing realm in challenge");
michael@0:         }
michael@0:         if (getParameter("nonce") == null) {
michael@0:             throw new MalformedChallengeException("missing nonce in challenge");
michael@0:         }
michael@0:         this.complete = true;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Tests if the Digest authentication process has been completed.
michael@0:      *
michael@0:      * @return <tt>true</tt> if Digest authorization has been processed,
michael@0:      *   <tt>false</tt> otherwise.
michael@0:      */
michael@0:     public boolean isComplete() {
michael@0:         String s = getParameter("stale");
michael@0:         if ("true".equalsIgnoreCase(s)) {
michael@0:             return false;
michael@0:         } else {
michael@0:             return this.complete;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Returns textual designation of the digest authentication scheme.
michael@0:      *
michael@0:      * @return <code>digest</code>
michael@0:      */
michael@0:     public String getSchemeName() {
michael@0:         return "digest";
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Returns <tt>false</tt>. Digest authentication scheme is request based.
michael@0:      *
michael@0:      * @return <tt>false</tt>.
michael@0:      */
michael@0:     public boolean isConnectionBased() {
michael@0:         return false;
michael@0:     }
michael@0: 
michael@0:     public void overrideParamter(final String name, final String value) {
michael@0:         getParameters().put(name, value);
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Produces a digest authorization string for the given set of
michael@0:      * {@link Credentials}, method name and URI.
michael@0:      *
michael@0:      * @param credentials A set of credentials to be used for athentication
michael@0:      * @param request    The request being authenticated
michael@0:      *
michael@0:      * @throws ch.boye.httpclientandroidlib.auth.InvalidCredentialsException if authentication credentials
michael@0:      *         are not valid or not applicable for this authentication scheme
michael@0:      * @throws AuthenticationException if authorization string cannot
michael@0:      *   be generated due to an authentication failure
michael@0:      *
michael@0:      * @return a digest authorization string
michael@0:      */
michael@0:     public Header authenticate(
michael@0:             final Credentials credentials,
michael@0:             final HttpRequest request) throws AuthenticationException {
michael@0: 
michael@0:         if (credentials == null) {
michael@0:             throw new IllegalArgumentException("Credentials may not be null");
michael@0:         }
michael@0:         if (request == null) {
michael@0:             throw new IllegalArgumentException("HTTP request may not be null");
michael@0:         }
michael@0: 
michael@0:         // Add method name and request-URI to the parameter map
michael@0:         getParameters().put("methodname", request.getRequestLine().getMethod());
michael@0:         getParameters().put("uri", request.getRequestLine().getUri());
michael@0:         String charset = getParameter("charset");
michael@0:         if (charset == null) {
michael@0:             charset = AuthParams.getCredentialCharset(request.getParams());
michael@0:             getParameters().put("charset", charset);
michael@0:         }
michael@0:         return createDigestHeader(credentials);
michael@0:     }
michael@0: 
michael@0:     private static MessageDigest createMessageDigest(
michael@0:             final String digAlg) throws UnsupportedDigestAlgorithmException {
michael@0:         try {
michael@0:             return MessageDigest.getInstance(digAlg);
michael@0:         } catch (Exception e) {
michael@0:             throw new UnsupportedDigestAlgorithmException(
michael@0:               "Unsupported algorithm in HTTP Digest authentication: "
michael@0:                + digAlg);
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Creates digest-response header as defined in RFC2617.
michael@0:      *
michael@0:      * @param credentials User credentials
michael@0:      *
michael@0:      * @return The digest-response as String.
michael@0:      */
michael@0:     private Header createDigestHeader(
michael@0:             final Credentials credentials) throws AuthenticationException {
michael@0:         String uri = getParameter("uri");
michael@0:         String realm = getParameter("realm");
michael@0:         String nonce = getParameter("nonce");
michael@0:         String opaque = getParameter("opaque");
michael@0:         String method = getParameter("methodname");
michael@0:         String algorithm = getParameter("algorithm");
michael@0:         if (uri == null) {
michael@0:             throw new IllegalStateException("URI may not be null");
michael@0:         }
michael@0:         if (realm == null) {
michael@0:             throw new IllegalStateException("Realm may not be null");
michael@0:         }
michael@0:         if (nonce == null) {
michael@0:             throw new IllegalStateException("Nonce may not be null");
michael@0:         }
michael@0: 
michael@0:         //TODO: add support for QOP_INT
michael@0:         int qop = QOP_UNKNOWN;
michael@0:         String qoplist = getParameter("qop");
michael@0:         if (qoplist != null) {
michael@0:             StringTokenizer tok = new StringTokenizer(qoplist, ",");
michael@0:             while (tok.hasMoreTokens()) {
michael@0:                 String variant = tok.nextToken().trim();
michael@0:                 if (variant.equals("auth")) {
michael@0:                     qop = QOP_AUTH;
michael@0:                     break;
michael@0:                 }
michael@0:             }
michael@0:         } else {
michael@0:             qop = QOP_MISSING;
michael@0:         }
michael@0: 
michael@0:         if (qop == QOP_UNKNOWN) {
michael@0:             throw new AuthenticationException("None of the qop methods is supported: " + qoplist);
michael@0:         }
michael@0: 
michael@0:         // If an algorithm is not specified, default to MD5.
michael@0:         if (algorithm == null) {
michael@0:             algorithm = "MD5";
michael@0:         }
michael@0:         // If an charset is not specified, default to ISO-8859-1.
michael@0:         String charset = getParameter("charset");
michael@0:         if (charset == null) {
michael@0:             charset = "ISO-8859-1";
michael@0:         }
michael@0: 
michael@0:         String digAlg = algorithm;
michael@0:         if (digAlg.equalsIgnoreCase("MD5-sess")) {
michael@0:             digAlg = "MD5";
michael@0:         }
michael@0: 
michael@0:         MessageDigest digester;
michael@0:         try {
michael@0:             digester = createMessageDigest(digAlg);
michael@0:         } catch (UnsupportedDigestAlgorithmException ex) {
michael@0:             throw new AuthenticationException("Unsuppported digest algorithm: " + digAlg);
michael@0:         }
michael@0: 
michael@0:         String uname = credentials.getUserPrincipal().getName();
michael@0:         String pwd = credentials.getPassword();
michael@0: 
michael@0:         if (nonce.equals(this.lastNonce)) {
michael@0:             nounceCount++;
michael@0:         } else {
michael@0:             nounceCount = 1;
michael@0:             cnonce = null;
michael@0:             lastNonce = nonce;
michael@0:         }
michael@0:         StringBuilder sb = new StringBuilder(256);
michael@0:         Formatter formatter = new Formatter(sb, Locale.US);
michael@0:         formatter.format("%08x", nounceCount);
michael@0:         String nc = sb.toString();
michael@0: 
michael@0:         if (cnonce == null) {
michael@0:             cnonce = createCnonce();
michael@0:         }
michael@0: 
michael@0:         a1 = null;
michael@0:         a2 = null;
michael@0:         // 3.2.2.2: Calculating digest
michael@0:         if (algorithm.equalsIgnoreCase("MD5-sess")) {
michael@0:             // H( unq(username-value) ":" unq(realm-value) ":" passwd )
michael@0:             //      ":" unq(nonce-value)
michael@0:             //      ":" unq(cnonce-value)
michael@0: 
michael@0:             // calculated one per session
michael@0:             sb.setLength(0);
michael@0:             sb.append(uname).append(':').append(realm).append(':').append(pwd);
michael@0:             String checksum = encode(digester.digest(EncodingUtils.getBytes(sb.toString(), charset)));
michael@0:             sb.setLength(0);
michael@0:             sb.append(checksum).append(':').append(nonce).append(':').append(cnonce);
michael@0:             a1 = sb.toString();
michael@0:         } else {
michael@0:             // unq(username-value) ":" unq(realm-value) ":" passwd
michael@0:             sb.setLength(0);
michael@0:             sb.append(uname).append(':').append(realm).append(':').append(pwd);
michael@0:             a1 = sb.toString();
michael@0:         }
michael@0: 
michael@0:         String hasha1 = encode(digester.digest(EncodingUtils.getBytes(a1, charset)));
michael@0: 
michael@0:         if (qop == QOP_AUTH) {
michael@0:             // Method ":" digest-uri-value
michael@0:             a2 = method + ':' + uri;
michael@0:         } else if (qop == QOP_AUTH_INT) {
michael@0:             // Method ":" digest-uri-value ":" H(entity-body)
michael@0:             //TODO: calculate entity hash if entity is repeatable
michael@0:             throw new AuthenticationException("qop-int method is not suppported");
michael@0:         } else {
michael@0:             a2 = method + ':' + uri;
michael@0:         }
michael@0: 
michael@0:         String hasha2 = encode(digester.digest(EncodingUtils.getBytes(a2, charset)));
michael@0: 
michael@0:         // 3.2.2.1
michael@0: 
michael@0:         String digestValue;
michael@0:         if (qop == QOP_MISSING) {
michael@0:             sb.setLength(0);
michael@0:             sb.append(hasha1).append(':').append(nonce).append(':').append(hasha2);
michael@0:             digestValue = sb.toString();
michael@0:         } else {
michael@0:             sb.setLength(0);
michael@0:             sb.append(hasha1).append(':').append(nonce).append(':').append(nc).append(':')
michael@0:                 .append(cnonce).append(':').append(qop == QOP_AUTH_INT ? "auth-int" : "auth")
michael@0:                 .append(':').append(hasha2);
michael@0:             digestValue = sb.toString();
michael@0:         }
michael@0: 
michael@0:         String digest = encode(digester.digest(EncodingUtils.getAsciiBytes(digestValue)));
michael@0: 
michael@0:         CharArrayBuffer buffer = new CharArrayBuffer(128);
michael@0:         if (isProxy()) {
michael@0:             buffer.append(AUTH.PROXY_AUTH_RESP);
michael@0:         } else {
michael@0:             buffer.append(AUTH.WWW_AUTH_RESP);
michael@0:         }
michael@0:         buffer.append(": Digest ");
michael@0: 
michael@0:         List<BasicNameValuePair> params = new ArrayList<BasicNameValuePair>(20);
michael@0:         params.add(new BasicNameValuePair("username", uname));
michael@0:         params.add(new BasicNameValuePair("realm", realm));
michael@0:         params.add(new BasicNameValuePair("nonce", nonce));
michael@0:         params.add(new BasicNameValuePair("uri", uri));
michael@0:         params.add(new BasicNameValuePair("response", digest));
michael@0: 
michael@0:         if (qop != QOP_MISSING) {
michael@0:             params.add(new BasicNameValuePair("qop", qop == QOP_AUTH_INT ? "auth-int" : "auth"));
michael@0:             params.add(new BasicNameValuePair("nc", nc));
michael@0:             params.add(new BasicNameValuePair("cnonce", cnonce));
michael@0:         }
michael@0:         if (algorithm != null) {
michael@0:             params.add(new BasicNameValuePair("algorithm", algorithm));
michael@0:         }
michael@0:         if (opaque != null) {
michael@0:             params.add(new BasicNameValuePair("opaque", opaque));
michael@0:         }
michael@0: 
michael@0:         for (int i = 0; i < params.size(); i++) {
michael@0:             BasicNameValuePair param = params.get(i);
michael@0:             if (i > 0) {
michael@0:                 buffer.append(", ");
michael@0:             }
michael@0:             boolean noQuotes = "nc".equals(param.getName()) || "qop".equals(param.getName());
michael@0:             BasicHeaderValueFormatter.DEFAULT.formatNameValuePair(buffer, param, !noQuotes);
michael@0:         }
michael@0:         return new BufferedHeader(buffer);
michael@0:     }
michael@0: 
michael@0:     String getCnonce() {
michael@0:         return cnonce;
michael@0:     }
michael@0: 
michael@0:     String getA1() {
michael@0:         return a1;
michael@0:     }
michael@0: 
michael@0:     String getA2() {
michael@0:         return a2;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Encodes the 128 bit (16 bytes) MD5 digest into a 32 characters long
michael@0:      * <CODE>String</CODE> according to RFC 2617.
michael@0:      *
michael@0:      * @param binaryData array containing the digest
michael@0:      * @return encoded MD5, or <CODE>null</CODE> if encoding failed
michael@0:      */
michael@0:     private static String encode(byte[] binaryData) {
michael@0:         int n = binaryData.length;
michael@0:         char[] buffer = new char[n * 2];
michael@0:         for (int i = 0; i < n; i++) {
michael@0:             int low = (binaryData[i] & 0x0f);
michael@0:             int high = ((binaryData[i] & 0xf0) >> 4);
michael@0:             buffer[i * 2] = HEXADECIMAL[high];
michael@0:             buffer[(i * 2) + 1] = HEXADECIMAL[low];
michael@0:         }
michael@0: 
michael@0:         return new String(buffer);
michael@0:     }
michael@0: 
michael@0: 
michael@0:     /**
michael@0:      * Creates a random cnonce value based on the current time.
michael@0:      *
michael@0:      * @return The cnonce value as String.
michael@0:      */
michael@0:     public static String createCnonce() {
michael@0:         SecureRandom rnd = new SecureRandom();
michael@0:         byte[] tmp = new byte[8];
michael@0:         rnd.nextBytes(tmp);
michael@0:         return encode(tmp);
michael@0:     }
michael@0: 
michael@0: }