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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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package com.sun.security.sasl;
import javax.security.sasl.*;
import javax.security.auth.callback.*;
import java.util.Random;
import java.util.Map;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.NoSuchAlgorithmException;
import java.util.logging.Logger;
import java.util.logging.Level;
/**
* Implements the CRAM-MD5 SASL server-side mechanism.
* (<A HREF="http://www.ietf.org/rfc/rfc2195.txt">RFC 2195</A>).
* CRAM-MD5 has no initial response.
*
* client <---- M={random, timestamp, server-fqdn} ------- server
* client ----- {username HMAC_MD5(pw, M)} --------------> server
*
* CallbackHandler must be able to handle the following callbacks:
* - NameCallback: default name is name of user for whom to get password
* - PasswordCallback: must fill in password; if empty, no pw
* - AuthorizeCallback: must setAuthorized() and canonicalized authorization id
* - auth id == authzid, but needed to get canonicalized authzid
*
* @author Rosanna Lee
*/
final class CramMD5Server extends CramMD5Base implements SaslServer {
private String fqdn;
private byte[] challengeData = null;
private String authzid;
private CallbackHandler cbh;
/**
* Creates a SASL mechanism with client credentials that it needs
* to participate in CRAM-MD5 authentication exchange with the server.
*
* @param authID A non-null string representing the principal
* being authenticated.
*
* @param pw A non-null String or byte[]
* containing the password. If it is an array, it is first cloned.
*/
CramMD5Server(String protocol, String serverFqdn, Map props,
CallbackHandler cbh) throws SaslException {
if (serverFqdn == null) {
throw new SaslException(
"CRAM-MD5: fully qualified server name must be specified");
}
fqdn = serverFqdn;
this.cbh = cbh;
}
/**
* Generates challenge based on response sent by client.
*
* CRAM-MD5 has no initial response.
* First call generates challenge.
* Second call verifies client response. If authentication fails, throws
* SaslException.
*
* @param responseData A non-null byte array containing the response
* data from the client.
* @return A non-null byte array containing the challenge to be sent to
* the client for the first call; null when 2nd call is successful.
* @throws SaslException If authentication fails.
*/
public byte[] evaluateResponse(byte[] responseData)
throws SaslException {
// See if we've been here before
if (completed) {
throw new IllegalStateException(
"CRAM-MD5 authentication already completed");
}
if (aborted) {
throw new IllegalStateException(
"CRAM-MD5 authentication previously aborted due to error");
}
try {
if (challengeData == null) {
if (responseData.length != 0) {
aborted = true;
throw new SaslException(
"CRAM-MD5 does not expect any initial response");
}
// Generate challenge {random, timestamp, fqdn}
Random random = new Random();
long rand = random.nextLong();
long timestamp = System.currentTimeMillis();
StringBuffer buf = new StringBuffer();
buf.append('<');
buf.append(rand);
buf.append('.');
buf.append(timestamp);
buf.append('@');
buf.append(fqdn);
buf.append('>');
String challengeStr = buf.toString();
logger.log(Level.FINE,
"CRAMSRV01:Generated challenge: {0}", challengeStr);
challengeData = challengeStr.getBytes("UTF8");
return challengeData.clone();
} else {
// Examine response to see if correctly encrypted challengeData
if(logger.isLoggable(Level.FINE)) {
logger.log(Level.FINE,
"CRAMSRV02:Received response: {0}",
new String(responseData, "UTF8"));
}
// Extract username from response
int ulen = 0;
for (int i = 0; i < responseData.length; i++) {
if (responseData[i] == ' ') {
ulen = i;
break;
}
}
if (ulen == 0) {
aborted = true;
throw new SaslException(
"CRAM-MD5: Invalid response; space missing");
}
String username = new String(responseData, 0, ulen, "UTF8");
logger.log(Level.FINE,
"CRAMSRV03:Extracted username: {0}", username);
// Get user's password
NameCallback ncb =
new NameCallback("CRAM-MD5 authentication ID: ", username);
PasswordCallback pcb =
new PasswordCallback("CRAM-MD5 password: ", false);
cbh.handle(new Callback[]{ncb,pcb});
char pwChars[] = pcb.getPassword();
if (pwChars == null || pwChars.length == 0) {
// user has no password; OK to disclose to server
aborted = true;
throw new SaslException(
"CRAM-MD5: username not found: " + username);
}
pcb.clearPassword();
String pwStr = new String(pwChars);
for (int i = 0; i < pwChars.length; i++) {
pwChars[i] = 0;
}
pw = pwStr.getBytes("UTF8");
// Generate a keyed-MD5 digest from the user's password and
// original challenge.
String digest = HMAC_MD5(pw, challengeData);
logger.log(Level.FINE,
"CRAMSRV04:Expecting digest: {0}", digest);
// clear pw when we no longer need it
clearPassword();
// Check whether digest is as expected
byte [] expectedDigest = digest.getBytes("UTF8");
int digestLen = responseData.length - ulen - 1;
if (expectedDigest.length != digestLen) {
aborted = true;
throw new SaslException("Invalid response");
}
int j = 0;
for (int i = ulen + 1; i < responseData.length ; i++) {
if (expectedDigest[j++] != responseData[i]) {
aborted = true;
throw new SaslException("Invalid response");
}
}
// All checks out, use AuthorizeCallback to canonicalize name
AuthorizeCallback acb = new AuthorizeCallback(username, username);
cbh.handle(new Callback[]{acb});
if (acb.isAuthorized()) {
authzid = acb.getAuthorizedID();
} else {
// Not authorized
aborted = true;
throw new SaslException(
"CRAM-MD5: user not authorized: " + username);
}
logger.log(Level.FINE,
"CRAMSRV05:Authorization id: {0}", authzid);
completed = true;
return null;
}
} catch (UnsupportedEncodingException e) {
aborted = true;
throw new SaslException("UTF8 not available on platform", e);
} catch (NoSuchAlgorithmException e) {
aborted = true;
throw new SaslException("MD5 algorithm not available on platform", e);
} catch (UnsupportedCallbackException e) {
aborted = true;
throw new SaslException("CRAM-MD5 authentication failed", e);
} catch (SaslException e) {
throw e; // rethrow
} catch (IOException e) {
aborted = true;
throw new SaslException("CRAM-MD5 authentication failed", e);
}
}
public String getAuthorizationID() {
if (completed) {
return authzid;
} else {
throw new IllegalStateException(
"CRAM-MD5 authentication not completed");
}
}
}