panda.net.pop3.ExtendedPOP3Client Maven / Gradle / Ivy

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Panda Nets is a client side library of many basic Internet protocols.
There is a newer version: 1.8.0
package panda.net.pop3;

import java.io.IOException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

import panda.codec.binary.Base64;

/**
 * A POP3 Cilent class with protocol and authentication extensions support (RFC2449 and RFC2195).
 * 
 * @see POP3Client
 */
public class ExtendedPOP3Client extends POP3SClient {
	/**
	 * The default ExtendedPOP3Client constructor. Creates a new Extended POP3 Client.
	 * 
	 * @throws NoSuchAlgorithmException on error
	 */
	public ExtendedPOP3Client() throws NoSuchAlgorithmException {
		super();
	}

	/***
	 * Authenticate to the POP3 server by sending the AUTH command with the selected mechanism,
	 * using the given username and the given password.
	 * 
	 * 
	 * @param method the {@link AUTH_METHOD} to use
	 * @param username the user name
	 * @param password the password
	 * @return True if successfully completed, false if not.
	 * @exception IOException If an I/O error occurs while either sending a command to the server or
	 *                receiving a reply from the server.
	 * @exception NoSuchAlgorithmException If the CRAM hash algorithm cannot be instantiated by the
	 *                Java runtime system.
	 * @exception InvalidKeyException If the CRAM hash algorithm failed to use the given password.
	 * @exception InvalidKeySpecException If the CRAM hash algorithm failed to use the given
	 *                password.
	 ***/
	public boolean auth(AUTH_METHOD method, String username, String password) throws IOException,
			NoSuchAlgorithmException, InvalidKeyException, InvalidKeySpecException {
		if (sendCommand(POP3Command.AUTH, method.getAuthName()) != POP3Reply.OK_INT) {
			return false;
		}

		switch (method) {
		case PLAIN:
			// the server sends an empty response ("+ "), so we don't have to read it.
			return sendCommand(new String(Base64.encodeBase64(("\000" + username + "\000" + password)
				.getBytes(getCharsetName())), getCharsetName()) // Java 1.6 can use getCharset()
			) == POP3Reply.OK;
		case CRAM_MD5:
			// get the CRAM challenge
			byte[] serverChallenge = Base64.decodeBase64(getReplyString().substring(2).trim());
			// get the Mac instance
			Mac hmac_md5 = Mac.getInstance("HmacMD5");
			hmac_md5.init(new SecretKeySpec(password.getBytes(getCharsetName()), "HmacMD5")); // Java
																								// 1.6
																								// can
																								// use
																								// getCharset()
			// compute the result:
			// Java 1.6 can use getCharset()
			byte[] hmacResult = _convertToHexString(hmac_md5.doFinal(serverChallenge)).getBytes(getCharsetName());
			// join the byte arrays to form the reply
			byte[] usernameBytes = username.getBytes(getCharsetName()); // Java 1.6 can use
																		// getCharset()
			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 sendCommand(Base64.encodeBase64String(toEncode)) == POP3Reply.OK;
		default:
			return false;
		}
	}

	/**
	 * 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(byte[] a) {
		StringBuilder result = new StringBuilder(a.length * 2);
		for (byte element : a) {
			if ((element & 0x0FF) <= 15) {
				result.append("0");
			}
			result.append(Integer.toHexString(element & 0x0FF));
		}
		return result.toString();
	}

	/**
	 * The enumeration of currently-supported authentication methods.
	 */
	public static enum AUTH_METHOD {
		/** The standarised (RFC4616) PLAIN method, which sends the password unencrypted (insecure). */
		PLAIN("PLAIN"),

		/** The standarised (RFC2195) CRAM-MD5 method, which doesn't send the password (secure). */
		CRAM_MD5("CRAM-MD5");

		private final String methodName;

		AUTH_METHOD(String methodName) {
			this.methodName = methodName;
		}

		/**
		 * 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 this.methodName;
		}
	}
}