AuthenticatingSMTPClient.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.smtp;
import java.io.IOException;
import java.net.InetAddress;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.util.Arrays;
import java.util.Base64;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import javax.net.ssl.SSLContext;
/**
* An SMTP Client class with authentication support (RFC4954).
*
* @see SMTPClient
* @since 3.0
*/
public class AuthenticatingSMTPClient extends SMTPSClient {
/** {@link Mac} algorithm. */
private static final String MAC_ALGORITHM = "HmacMD5";
/**
* The enumeration of currently-supported authentication methods.
*/
public enum AUTH_METHOD {
/** The standardized (RFC4616) PLAIN method, which sends the password unencrypted (insecure). */
PLAIN,
/** The standardized (RFC2195) CRAM-MD5 method, which doesn't send the password (secure). */
CRAM_MD5,
/** The non-standarized Microsoft LOGIN method, which sends the password unencrypted (insecure). */
LOGIN,
/** XOAuth method which accepts a signed and base64ed OAuth URL. */
XOAUTH,
/** XOAuth 2 method which accepts a signed and base64ed OAuth JSON. */
XOAUTH2;
/**
* Gets the name of the given authentication method suitable for the server.
*
* @param method The authentication method to get the name for.
* @return The name of the given authentication method suitable for the server.
*/
public static final String getAuthName(final AUTH_METHOD method) {
if (method.equals(AUTH_METHOD.PLAIN)) {
return "PLAIN";
}
if (method.equals(AUTH_METHOD.CRAM_MD5)) {
return "CRAM-MD5";
}
if (method.equals(AUTH_METHOD.LOGIN)) {
return "LOGIN";
}
if (method.equals(AUTH_METHOD.XOAUTH)) {
return "XOAUTH";
}
if (method.equals(AUTH_METHOD.XOAUTH2)) {
return "XOAUTH2";
}
return null;
}
}
/**
* The default AuthenticatingSMTPClient constructor. Creates a new Authenticating SMTP Client.
*/
public AuthenticatingSMTPClient() {
}
/**
* Overloaded constructor that takes the implicit argument, and using {@link #DEFAULT_PROTOCOL} i.e. TLS
*
* @param implicit The security mode, {@code true} for implicit, {@code false} for explicit
* @param ctx A pre-configured SSL Context.
* @since 3.3
*/
public AuthenticatingSMTPClient(final boolean implicit, final SSLContext ctx) {
super(implicit, ctx);
}
/**
* Overloaded constructor that takes a protocol specification
*
* @param protocol The protocol to use
*/
public AuthenticatingSMTPClient(final String protocol) {
super(protocol);
}
/**
* Overloaded constructor that takes a protocol specification and the implicit argument
*
* @param proto the protocol.
* @param implicit The security mode, {@code true} for implicit, {@code false} for explicit
* @since 3.3
*/
public AuthenticatingSMTPClient(final String proto, final boolean implicit) {
super(proto, implicit);
}
/**
* Overloaded constructor that takes the protocol specification, the implicit argument and encoding
*
* @param proto the protocol.
* @param implicit The security mode, {@code true} for implicit, {@code false} for explicit
* @param encoding the encoding
* @since 3.3
*/
public AuthenticatingSMTPClient(final String proto, final boolean implicit, final String encoding) {
super(proto, implicit, encoding);
}
/**
* Overloaded constructor that takes a protocol specification and encoding
*
* @param protocol The protocol to use
* @param encoding The encoding to use
* @since 3.3
*/
public AuthenticatingSMTPClient(final String protocol, final String encoding) {
super(protocol, false, encoding);
}
/**
* Authenticate to the SMTP server by sending the AUTH command with the selected mechanism, using the given user and the given password.
*
* @param method the method to use, one of the {@link AuthenticatingSMTPClient.AUTH_METHOD} enum values
* @param user the user name. If the method is XOAUTH/XOAUTH2, then this is used as the plain text oauth protocol parameter string which is
* Base64-encoded for transmission.
* @param password the password for the username. Ignored for XOAUTH/XOAUTH2.
*
* @return True if successfully completed, false if not.
* @throws SMTPConnectionClosedException If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason
* causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or
* independently as itself.
* @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 AuthenticatingSMTPClient.AUTH_METHOD method, final String user, final String password)
throws IOException, NoSuchAlgorithmException, InvalidKeyException, InvalidKeySpecException {
if (!SMTPReply.isPositiveIntermediate(sendCommand(SMTPCommand.AUTH, AUTH_METHOD.getAuthName(method)))) {
return false;
}
if (method.equals(AUTH_METHOD.PLAIN)) {
// the server sends an empty response ("334 "), so we don't have to read it.
return SMTPReply
.isPositiveCompletion(sendCommand(Base64.getEncoder().encodeToString(("\000" + user + "\000" + password).getBytes(getCharset()))));
}
if (method.equals(AUTH_METHOD.CRAM_MD5)) {
// get the CRAM challenge
final byte[] serverChallenge = Base64.getDecoder().decode(getReplyString().substring(4).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:
return SMTPReply.isPositiveCompletion(sendCommand(Base64.getEncoder().encodeToString(toEncode)));
}
if (method.equals(AUTH_METHOD.LOGIN)) {
// the server sends fixed responses (base64("Username") and
// base64("Password")), so we don't have to read them.
if (!SMTPReply.isPositiveIntermediate(sendCommand(Base64.getEncoder().encodeToString(user.getBytes(getCharset()))))) {
return false;
}
return SMTPReply.isPositiveCompletion(sendCommand(Base64.getEncoder().encodeToString(password.getBytes(getCharset()))));
}
if (method.equals(AUTH_METHOD.XOAUTH) || method.equals(AUTH_METHOD.XOAUTH2)) {
return SMTPReply.isPositiveIntermediate(sendCommand(Base64.getEncoder().encodeToString(user.getBytes(getCharset()))));
}
return false; // safety check
}
/**
* Converts the given byte array to a String containing the hex 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 hex 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();
}
/**
* A convenience method to send the ESMTP EHLO command to the server, receive the reply, and return the reply code.
*
* @param hostname The hostname of the sender.
* @return The reply code received from the server.
* @throws SMTPConnectionClosedException If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason
* causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or
* independently as itself.
* @throws IOException If an I/O error occurs while either sending the command or receiving the server reply.
*/
public int ehlo(final String hostname) throws IOException {
return sendCommand(SMTPCommand.EHLO, hostname);
}
/**
* Login to the ESMTP server by sending the EHLO command with the client hostname as an argument. Before performing any mail commands, you must first login.
*
* @return True if successfully completed, false if not.
* @throws SMTPConnectionClosedException If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason
* causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or
* independently as itself.
* @throws IOException If an I/O error occurs while either sending a command to the server or receiving a reply from the server.
*/
public boolean elogin() throws IOException {
final String name;
final InetAddress host;
host = getLocalAddress();
name = host.getHostName();
if (name == null) {
return false;
}
return SMTPReply.isPositiveCompletion(ehlo(name));
}
/**
* Login to the ESMTP server by sending the EHLO command with the given hostname as an argument. Before performing any mail commands, you must first login.
*
* @param hostname The hostname with which to greet the SMTP server.
* @return True if successfully completed, false if not.
* @throws SMTPConnectionClosedException If the SMTP server prematurely closes the connection as a result of the client being idle or some other reason
* causing the server to send SMTP reply code 421. This exception may be caught either as an IOException or
* independently as itself.
* @throws IOException If an I/O error occurs while either sending a command to the server or receiving a reply from the server.
*/
public boolean elogin(final String hostname) throws IOException {
return SMTPReply.isPositiveCompletion(ehlo(hostname));
}
/**
* Returns the integer values of the enhanced reply code of the last SMTP reply.
*
* @return The integer values of the enhanced reply code of the last SMTP reply. First digit is in the first array element.
*/
public int[] getEnhancedReplyCode() {
final String reply = getReplyString().substring(4);
final String[] parts = reply.substring(0, reply.indexOf(' ')).split("\\.");
final int[] res = new int[parts.length];
Arrays.setAll(res, i -> Integer.parseInt(parts[i]));
return res;
}
}