AuthenticatingIMAPClient.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.net.imap;
import java.io.IOException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.util.Base64;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import javax.net.ssl.SSLContext;
/**
* An IMAP Client class with authentication support.
*
* @see IMAPSClient
*/
public class AuthenticatingIMAPClient extends IMAPSClient {
/**
* The enumeration of currently-supported authentication methods.
*/
public enum AUTH_METHOD {
/** The standardized (RFC4616) PLAIN method, which sends the password unencrypted (insecure). */
PLAIN("PLAIN"),
/** The standardized (RFC2195) CRAM-MD5 method, which doesn't send the password (secure). */
CRAM_MD5("CRAM-MD5"),
/** The standardized Microsoft LOGIN method, which sends the password unencrypted (insecure). */
LOGIN("LOGIN"),
/** XOAUTH */
XOAUTH("XOAUTH"),
/** XOAUTH 2 */
XOAUTH2("XOAUTH2");
private final String authName;
AUTH_METHOD(final String name) {
this.authName = name;
}
/**
* Gets the name of the given authentication method suitable for the server.
*
* @return The name of the given authentication method suitable for the server.
*/
public final String getAuthName() {
return authName;
}
}
/** {@link Mac} algorithm. */
private static final String MAC_ALGORITHM = "HmacMD5";
/**
* Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient. Sets security mode to explicit (isImplicit = false).
*/
public AuthenticatingIMAPClient() {
this(DEFAULT_PROTOCOL, false);
}
/**
* Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
*
* @param implicit The security mode (Implicit/Explicit).
*/
public AuthenticatingIMAPClient(final boolean implicit) {
this(DEFAULT_PROTOCOL, implicit);
}
/**
* Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
*
* @param implicit The security mode(Implicit/Explicit).
* @param ctx A pre-configured SSL Context.
*/
public AuthenticatingIMAPClient(final boolean implicit, final SSLContext ctx) {
this(DEFAULT_PROTOCOL, implicit, ctx);
}
/**
* Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
*
* @param context A pre-configured SSL Context.
*/
public AuthenticatingIMAPClient(final SSLContext context) {
this(false, context);
}
/**
* Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
*
* @param proto the protocol.
*/
public AuthenticatingIMAPClient(final String proto) {
this(proto, false);
}
/**
* Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
*
* @param proto the protocol.
* @param implicit The security mode(Implicit/Explicit).
*/
public AuthenticatingIMAPClient(final String proto, final boolean implicit) {
this(proto, implicit, null);
}
/**
* Constructor for AuthenticatingIMAPClient that delegates to IMAPSClient.
*
* @param proto the protocol.
* @param implicit The security mode(Implicit/Explicit).
* @param ctx the context
*/
public AuthenticatingIMAPClient(final String proto, final boolean implicit, final SSLContext ctx) {
super(proto, implicit, ctx);
}
/**
* Authenticate to the IMAP server by sending the AUTHENTICATE command with the selected mechanism, using the given user and the given password.
*
* @param method the method name
* @param user user
* @param password password
* @return True if successfully completed, false if not.
* @throws IOException If an I/O error occurs while either sending a command to the server or receiving a reply from the server.
* @throws NoSuchAlgorithmException If the CRAM hash algorithm cannot be instantiated by the Java runtime system.
* @throws InvalidKeyException If the CRAM hash algorithm failed to use the given password.
* @throws InvalidKeySpecException If the CRAM hash algorithm failed to use the given password.
*/
public boolean auth(final AuthenticatingIMAPClient.AUTH_METHOD method, final String user, final String password)
throws IOException, NoSuchAlgorithmException, InvalidKeyException, InvalidKeySpecException {
if (!IMAPReply.isContinuation(sendCommand(IMAPCommand.AUTHENTICATE, method.getAuthName()))) {
return false;
}
switch (method) {
case PLAIN: {
// the server sends an empty response ("+ "), so we don't have to read it.
final int result = sendData(Base64.getEncoder().encodeToString(("\000" + user + "\000" + password).getBytes(getCharset())));
if (result == IMAPReply.OK) {
setState(IMAP.IMAPState.AUTH_STATE);
}
return result == IMAPReply.OK;
}
case CRAM_MD5: {
// get the CRAM challenge (after "+ ")
final byte[] serverChallenge = Base64.getDecoder().decode(getReplyString().substring(2).trim());
// get the Mac instance
final Mac hmacMd5 = Mac.getInstance(MAC_ALGORITHM);
hmacMd5.init(new SecretKeySpec(password.getBytes(getCharset()), MAC_ALGORITHM));
// compute the result:
final byte[] hmacResult = convertToHexString(hmacMd5.doFinal(serverChallenge)).getBytes(getCharset());
// join the byte arrays to form the reply
final byte[] usernameBytes = user.getBytes(getCharset());
final byte[] toEncode = new byte[usernameBytes.length + 1 /* the space */ + hmacResult.length];
System.arraycopy(usernameBytes, 0, toEncode, 0, usernameBytes.length);
toEncode[usernameBytes.length] = ' ';
System.arraycopy(hmacResult, 0, toEncode, usernameBytes.length + 1, hmacResult.length);
// send the reply and read the server code:
final int result = sendData(Base64.getEncoder().encodeToString(toEncode));
if (result == IMAPReply.OK) {
setState(IMAP.IMAPState.AUTH_STATE);
}
return result == IMAPReply.OK;
}
case LOGIN: {
// the server sends fixed responses (base64("UserName") and
// base64("Password")), so we don't have to read them.
if (sendData(Base64.getEncoder().encodeToString(user.getBytes(getCharset()))) != IMAPReply.CONT) {
return false;
}
final int result = sendData(Base64.getEncoder().encodeToString(password.getBytes(getCharset())));
if (result == IMAPReply.OK) {
setState(IMAP.IMAPState.AUTH_STATE);
}
return result == IMAPReply.OK;
}
case XOAUTH:
case XOAUTH2: {
final int result = sendData(user);
if (result == IMAPReply.OK) {
setState(IMAP.IMAPState.AUTH_STATE);
}
return result == IMAPReply.OK;
}
}
return false; // safety check
}
/**
* Authenticate to the IMAP server by sending the AUTHENTICATE command with the selected mechanism, using the given user and the given password.
*
* @param method the method name
* @param user user
* @param password password
* @return True if successfully completed, false if not.
* @throws IOException If an I/O error occurs while either sending a command to the server or receiving a reply from the server.
* @throws NoSuchAlgorithmException If the CRAM hash algorithm cannot be instantiated by the Java runtime system.
* @throws InvalidKeyException If the CRAM hash algorithm failed to use the given password.
* @throws InvalidKeySpecException If the CRAM hash algorithm failed to use the given password.
*/
public boolean authenticate(final AuthenticatingIMAPClient.AUTH_METHOD method, final String user, final String password)
throws IOException, NoSuchAlgorithmException, InvalidKeyException, InvalidKeySpecException {
return auth(method, user, password);
}
/**
* Converts the given byte array to a String containing the hexadecimal values of the bytes. For example, the byte 'A' will be converted to '41', because
* this is the ASCII code (and the byte value) of the capital letter 'A'.
*
* @param a The byte array to convert.
* @return The resulting String of hexadecimal codes.
*/
private String convertToHexString(final byte[] a) {
final StringBuilder result = new StringBuilder(a.length * 2);
for (final byte element : a) {
if ((element & 0x0FF) <= 15) {
result.append("0");
}
result.append(Integer.toHexString(element & 0x0FF));
}
return result.toString();
}
}