    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      https://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.net.pop3;
    019
    020import java.io.BufferedWriter;
    021import java.io.IOException;
    022import java.io.InputStreamReader;
    023import java.io.OutputStreamWriter;
    024
    025import javax.net.ssl.HostnameVerifier;
    026import javax.net.ssl.KeyManager;
    027import javax.net.ssl.SSLContext;
    028import javax.net.ssl.SSLException;
    029import javax.net.ssl.SSLHandshakeException;
    030import javax.net.ssl.SSLSocket;
    031import javax.net.ssl.SSLSocketFactory;
    032import javax.net.ssl.TrustManager;
    033
    034import org.apache.commons.net.io.CRLFLineReader;
    035import org.apache.commons.net.util.SSLContextUtils;
    036import org.apache.commons.net.util.SSLSocketUtils;
    037
    038/**
    039 * POP3 over SSL processing. Copied from FTPSClient.java and modified to suit POP3. If implicit mode is selected (NOT the default), SSL/TLS negotiation starts
    040 * right after the connection has been established. In explicit mode (the default), SSL/TLS negotiation starts when the user calls execTLS() and the server
    041 * accepts the command. Implicit usage: POP3SClient c = new POP3SClient(true); c.connect("127.0.0.1", 995); Explicit usage: POP3SClient c = new POP3SClient();
    042 * c.connect("127.0.0.1", 110); if (c.execTLS()) { /rest of the commands here/ }
    043 *
    044 * Warning: the hostname is not verified against the certificate by default, use {@link #setHostnameVerifier(HostnameVerifier)} or
    045 * {@link #setEndpointCheckingEnabled(boolean)} (on Java 1.7+) to enable verification.
    046 *
    047 * @since 3.0
    048 */
    049public class POP3SClient extends POP3Client {
    050    // from http://www.iana.org/assignments/port-numbers
    051
    052    // pop3s 995/tcp pop3 protocol over TLS/SSL (was spop3)
    053    // pop3s 995/udp pop3 protocol over TLS/SSL (was spop3)
    054
    055    private static final int DEFAULT_POP3S_PORT = 995;
    056
    057    /** Default secure socket protocol name, like TLS */
    058    private static final String DEFAULT_PROTOCOL = "TLS";
    059
    060    /** The security mode. True - Implicit Mode / False - Explicit Mode. */
    061    private final boolean isImplicit;
    062    /** The secure socket protocol to be used, like SSL/TLS. */
    063    private final String protocol;
    064    /** The context object. */
    065    private SSLContext context;
    066    /**
    067     * The cipher suites. SSLSockets have a default set of these anyway, so no initialization required.
    068     */
    069    private String[] suites;
    070    /** The protocol versions. */
    071    private String[] protocols // null;
    072    ; // {"SSLv2", "SSLv3", "TLSv1", "TLSv1.1", "SSLv2Hello"};
    073
    074    /** The FTPS {@link TrustManager} implementation, default null. */
    075    private TrustManager trustManager;
    076
    077    /** The {@link KeyManager}, default null. */
    078    private KeyManager keyManager;
    079
    080    /** The {@link HostnameVerifier} to use post-TLS, default null (i.e. no verification). */
    081    private HostnameVerifier hostnameVerifier;
    082
    083    /** Use Java 1.7+ HTTPS Endpoint Identification Algorithm. */
    084    private boolean tlsEndpointChecking;
    085
    086    /**
    087     * Constructor for POP3SClient, using {@link #DEFAULT_PROTOCOL} i.e. TLS Sets security mode to explicit.
    088     */
    089    public POP3SClient() {
    090        this(DEFAULT_PROTOCOL, false);
    091    }
    092
    093    /**
    094     * Constructor for POP3SClient, using {@link #DEFAULT_PROTOCOL} i.e. TLS
    095     *
    096     * @param implicit The security mode, {@code true} for implicit, {@code false} for explicit
    097     */
    098    public POP3SClient(final boolean implicit) {
    099        this(DEFAULT_PROTOCOL, implicit);
    100    }
    101
    102    /**
    103     * Constructor for POP3SClient, using {@link #DEFAULT_PROTOCOL} i.e. TLS
    104     *
    105     * @param implicit The security mode, {@code true} for implicit, {@code false} for explicit
    106     * @param ctx      A pre-configured SSL Context.
    107     */
    108    public POP3SClient(final boolean implicit, final SSLContext ctx) {
    109        this(DEFAULT_PROTOCOL, implicit, ctx);
    110    }
    111
    112    /**
    113     * Constructor for POP3SClient, using {@link #DEFAULT_PROTOCOL} - TLS - and isImplicit = false
    114     *
    115     * @param context A pre-configured SSL Context.
    116     * @see #POP3SClient(boolean, SSLContext)
    117     */
    118    public POP3SClient(final SSLContext context) {
    119        this(false, context);
    120    }
    121
    122    /**
    123     * Constructor for POP3SClient. Sets security mode to explicit.
    124     *
    125     * @param proto the protocol.
    126     */
    127    public POP3SClient(final String proto) {
    128        this(proto, false);
    129    }
    130
    131    /**
    132     * Constructor for POP3SClient.
    133     *
    134     * @param proto    the protocol.
    135     * @param implicit The security mode, {@code true} for implicit, {@code false} for explicit
    136     */
    137    public POP3SClient(final String proto, final boolean implicit) {
    138        this(proto, implicit, null);
    139    }
    140
    141    /**
    142     * Constructor for POP3SClient. Sets the default port to {@link #DEFAULT_POP3S_PORT} - 995 - if using implicit mode
    143     *
    144     * @param proto    the protocol.
    145     * @param implicit The security mode, {@code true} for implicit, {@code false} for explicit
    146     * @param ctx      the context to be used
    147     */
    148    public POP3SClient(final String proto, final boolean implicit, final SSLContext ctx) {
    149        protocol = proto;
    150        isImplicit = implicit;
    151        context = ctx;
    152        if (isImplicit) {
    153            setDefaultPort(DEFAULT_POP3S_PORT);
    154        }
    155    }
    156
    157    /**
    158     * Because there are so many connect() methods, the _connectAction_() method is provided as a means of performing some action immediately after establishing
    159     * a connection, rather than reimplementing all the connect() methods.
    160     *
    161     * @throws IOException If it is thrown by _connectAction_().
    162     * @see org.apache.commons.net.SocketClient#_connectAction_()
    163     */
    164    @Override
    165    protected void _connectAction_() throws IOException {
    166        // Implicit mode.
    167        if (isImplicit) {
    168            applySocketAttributes();
    169            performSSLNegotiation();
    170        }
    171        super._connectAction_();
    172        // Explicit mode - don't do anything. The user calls execTLS()
    173    }
    174
    175    /**
    176     * The TLS command execution.
    177     *
    178     * @throws SSLException If the server reply code is not positive.
    179     * @throws IOException  If an I/O error occurs while sending the command or performing the negotiation.
    180     * @return TRUE if the command and negotiation succeeded.
    181     */
    182    public boolean execTLS() throws SSLException, IOException {
    183        if (sendCommand("STLS") != POP3Reply.OK) {
    184            return false;
    185            // throw new SSLException(getReplyString());
    186        }
    187        performSSLNegotiation();
    188        return true;
    189    }
    190
    191    /**
    192     * Gets the names of the cipher suites which could be enabled for use on this connection. When the underlying {@link java.net.Socket Socket} is not an
    193     * {@link SSLSocket} instance, returns null.
    194     *
    195     * @return An array of cipher suite names, or {@code null}.
    196     */
    197    public String[] getEnabledCipherSuites() {
    198        if (_socket_ instanceof SSLSocket) {
    199            return ((SSLSocket) _socket_).getEnabledCipherSuites();
    200        }
    201        return null;
    202    }
    203
    204    /**
    205     * Gets the names of the protocol versions which are currently enabled for use on this connection. When the underlying {@link java.net.Socket Socket} is
    206     * not an {@link SSLSocket} instance, returns null.
    207     *
    208     * @return An array of protocols, or {@code null}.
    209     */
    210    public String[] getEnabledProtocols() {
    211        if (_socket_ instanceof SSLSocket) {
    212            return ((SSLSocket) _socket_).getEnabledProtocols();
    213        }
    214        return null;
    215    }
    216
    217    /**
    218     * Gets the currently configured {@link HostnameVerifier}.
    219     *
    220     * @return A HostnameVerifier instance.
    221     * @since 3.4
    222     */
    223    public HostnameVerifier getHostnameVerifier() {
    224        return hostnameVerifier;
    225    }
    226
    227    /**
    228     * Gets the {@link KeyManager} instance.
    229     *
    230     * @return The current {@link KeyManager} instance.
    231     */
    232    private KeyManager getKeyManager() {
    233        return keyManager;
    234    }
    235
    236    /**
    237     * Gets the currently configured {@link TrustManager}.
    238     *
    239     * @return A TrustManager instance.
    240     */
    241    public TrustManager getTrustManager() {
    242        return trustManager;
    243    }
    244
    245    /**
    246     * Performs a lazy init of the SSL context.
    247     *
    248     * @throws IOException When could not initialize the SSL context.
    249     */
    250    private void initSSLContext() throws IOException {
    251        if (context == null) {
    252            context = SSLContextUtils.createSSLContext(protocol, getKeyManager(), getTrustManager());
    253        }
    254    }
    255
    256    /**
    257     * Tests whether or not endpoint identification using the HTTPS algorithm on Java 1.7+ is enabled. The default behavior is for this to be disabled.
    258     *
    259     * @return True if enabled, false if not.
    260     * @since 3.4
    261     */
    262    public boolean isEndpointCheckingEnabled() {
    263        return tlsEndpointChecking;
    264    }
    265
    266    /**
    267     * SSL/TLS negotiation. Acquires an SSL socket of a connection and carries out handshake processing.
    268     *
    269     * @throws IOException If server negotiation fails.
    270     */
    271    private void performSSLNegotiation() throws IOException {
    272        initSSLContext();
    273
    274        final SSLSocketFactory ssf = context.getSocketFactory();
    275        final String host = _hostname_ != null ? _hostname_ : getRemoteAddress().getHostAddress();
    276        final int port = getRemotePort();
    277        final SSLSocket socket = (SSLSocket) ssf.createSocket(_socket_, host, port, true);
    278        socket.setEnableSessionCreation(true);
    279        socket.setUseClientMode(true);
    280
    281        if (tlsEndpointChecking) {
    282            SSLSocketUtils.enableEndpointNameVerification(socket);
    283        }
    284
    285        if (protocols != null) {
    286            socket.setEnabledProtocols(protocols);
    287        }
    288        if (suites != null) {
    289            socket.setEnabledCipherSuites(suites);
    290        }
    291        socket.startHandshake();
    292
    293        // TODO the following setup appears to duplicate that in the super class methods
    294        _socket_ = socket;
    295        _input_ = socket.getInputStream();
    296        _output_ = socket.getOutputStream();
    297        reader = new CRLFLineReader(new InputStreamReader(_input_, DEFAULT_ENCODING));
    298        writer = new BufferedWriter(new OutputStreamWriter(_output_, DEFAULT_ENCODING));
    299
    300        if (hostnameVerifier != null && !hostnameVerifier.verify(host, socket.getSession())) {
    301            throw new SSLHandshakeException("Hostname doesn't match certificate");
    302        }
    303    }
    304
    305    /**
    306     * Sets which particular cipher suites are enabled for use on this connection. Called before server negotiation.
    307     *
    308     * @param cipherSuites The cipher suites.
    309     */
    310    public void setEnabledCipherSuites(final String[] cipherSuites) {
    311        suites = cipherSuites.clone();
    312    }
    313
    314    /**
    315     * Sets which particular protocol versions are enabled for use on this connection. I perform setting before a server negotiation.
    316     *
    317     * @param protocolVersions The protocol versions.
    318     */
    319    public void setEnabledProtocols(final String[] protocolVersions) {
    320        protocols = protocolVersions.clone();
    321    }
    322
    323    /**
    324     * Sets automatic endpoint identification checking using the HTTPS algorithm is supported on Java 1.7+. The default behavior is for this to be disabled.
    325     *
    326     * @param enable Enable automatic endpoint identification checking using the HTTPS algorithm on Java 1.7+.
    327     * @since 3.4
    328     */
    329    public void setEndpointCheckingEnabled(final boolean enable) {
    330        tlsEndpointChecking = enable;
    331    }
    332
    333    /**
    334     * Sets to override the default {@link HostnameVerifier} to use.
    335     *
    336     * @param newHostnameVerifier The HostnameVerifier implementation to set or {@code null} to disable.
    337     * @since 3.4
    338     */
    339    public void setHostnameVerifier(final HostnameVerifier newHostnameVerifier) {
    340        hostnameVerifier = newHostnameVerifier;
    341    }
    342
    343    /**
    344     * Sets a {@link KeyManager} to use.
    345     *
    346     * @param newKeyManager The KeyManager implementation to set.
    347     * @see org.apache.commons.net.util.KeyManagerUtils
    348     */
    349    public void setKeyManager(final KeyManager newKeyManager) {
    350        keyManager = newKeyManager;
    351    }
    352
    353    /**
    354     * Sets to override the default {@link TrustManager} to use.
    355     *
    356     * @param newTrustManager The TrustManager implementation to set.
    357     * @see org.apache.commons.net.util.TrustManagerUtils
    358     */
    359    public void setTrustManager(final TrustManager newTrustManager) {
    360        trustManager = newTrustManager;
    361    }
    362}
    363