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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * This code is free software; you can redistribute it and/or modify it

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 * 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).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

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 *

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package com.sun.security.sasl.gsskerb;

import javax.security.sasl.*;

import java.io.*;

import java.util.Map;

import java.util.logging.Level;

// JAAS

import javax.security.auth.callback.*;

// JGSS

import org.ietf.jgss.*;

/**

  * Implements the GSSAPI SASL server mechanism for Kerberos V5.

  * (<A HREF="http://www.ietf.org/rfc/rfc2222.txt">RFC 2222</A>,

  * <a HREF="http://www.ietf.org/internet-drafts/draft-ietf-cat-sasl-gssapi-00.txt">draft-ietf-cat-sasl-gssapi-00.txt</a>).

  *

  * Expects thread's Subject to contain server's Kerberos credentials

  * - If not, underlying KRB5 mech will attempt to acquire Kerberos creds

  *   by logging into Kerberos (via default TextCallbackHandler).

  * - These creds will be used for exchange with client.

  *

  * Required callbacks:

  * - AuthorizeCallback

  *      handler must verify that authid/authzids are allowed and set

  *      authorized ID to be the canonicalized authzid (if applicable).

  *

  * Environment properties that affect behavior of implementation:

  *

  * javax.security.sasl.qop

  * - quality of protection; list of auth, auth-int, auth-conf; default is "auth"

  * javax.security.sasl.maxbuf

  * - max receive buffer size; default is 65536

  * javax.security.sasl.sendmaxbuffer

  * - max send buffer size; default is 65536; (min with client max recv size)

  *

  * @author Rosanna Lee

  */

final class GssKrb5Server extends GssKrb5Base implements SaslServer {

    private static final String MY_CLASS_NAME = GssKrb5Server.class.getName();

    private int handshakeStage = 0;

    private String peer;

    private String me;

    private String authzid;

    private CallbackHandler cbh;

    // When serverName is null, the server will be unbound. We need to save and

    // check the protocol name after the context is established. This value

    // will be null if serverName is not null.

    private final String protocolSaved;

    /**

     * Creates a SASL mechanism with server credentials that it needs

     * to participate in GSS-API/Kerberos v5 authentication exchange

     * with the client.

     */

    GssKrb5Server(String protocol, String serverName,

        Map<String, ?> props, CallbackHandler cbh) throws SaslException {

        super(props, MY_CLASS_NAME);

        this.cbh = cbh;

        String service;

        if (serverName == null) {

            protocolSaved = protocol;

            service = null;

        } else {

            protocolSaved = null;

            service = protocol + "@" + serverName;

        }

        logger.log(Level.FINE, "KRB5SRV01:Using service name: {0}", service);

        try {

            GSSManager mgr = GSSManager.getInstance();

            // Create the name for the requested service entity for Krb5 mech

            GSSName serviceName = service == null ? null:

                    mgr.createName(service, GSSName.NT_HOSTBASED_SERVICE, KRB5_OID);

            GSSCredential cred = mgr.createCredential(serviceName,

                GSSCredential.INDEFINITE_LIFETIME,

                KRB5_OID, GSSCredential.ACCEPT_ONLY);

            // Create a context using the server's credentials

            secCtx = mgr.createContext(cred);

            if ((allQop&INTEGRITY_ONLY_PROTECTION) != 0) {

                // Might need integrity

                secCtx.requestInteg(true);

            }

            if ((allQop&PRIVACY_PROTECTION) != 0) {

                // Might need privacy

                secCtx.requestConf(true);

            }

        } catch (GSSException e) {

            throw new SaslException("Failure to initialize security context", e);

        }

        logger.log(Level.FINE, "KRB5SRV02:Initialization complete");

    }

    /**

     * Processes the response data.

     *

     * The client sends response data to which the server must

     * process using GSS_accept_sec_context.

     * As per RFC 2222, the GSS authenication completes (GSS_S_COMPLETE)

     * we do an extra hand shake to determine the negotiated security protection

     * and buffer sizes.

     *

     * @param responseData A non-null but possible empty byte array containing the

     * response data from the client.

     * @return A non-null byte array containing the challenge to be

     * sent to the client, or null when no more data is to be sent.

     */

    public byte[] evaluateResponse(byte[] responseData) throws SaslException {

        if (completed) {

            throw new SaslException(

                "SASL authentication already complete");

        }

        if (logger.isLoggable(Level.FINER)) {

            traceOutput(MY_CLASS_NAME, "evaluateResponse",

                "KRB5SRV03:Response [raw]:", responseData);

        }

        switch (handshakeStage) {

        case 1:

            return doHandshake1(responseData);

        case 2:

            return doHandshake2(responseData);

        default:

            // Security context not established yet; continue with accept

            try {

                byte[] gssOutToken = secCtx.acceptSecContext(responseData,

                    0, responseData.length);

                if (logger.isLoggable(Level.FINER)) {

                    traceOutput(MY_CLASS_NAME, "evaluateResponse",

                        "KRB5SRV04:Challenge: [after acceptSecCtx]", gssOutToken);

                }

                if (secCtx.isEstablished()) {

                    handshakeStage = 1;

                    peer = secCtx.getSrcName().toString();

                    me = secCtx.getTargName().toString();

                    logger.log(Level.FINE,

                            "KRB5SRV05:Peer name is : {0}, my name is : {1}",

                            new Object[]{peer, me});

                    // me might take the form of proto@host or proto/host

                    if (protocolSaved != null &&

                            !protocolSaved.equalsIgnoreCase(me.split("[/@]")[0])) {

                        throw new SaslException(

                                "GSS context targ name protocol error: " + me);

                    }

                    if (gssOutToken == null) {

                        return doHandshake1(EMPTY);

                    }

                }

                return gssOutToken;

            } catch (GSSException e) {

                throw new SaslException("GSS initiate failed", e);

            }

        }

    }

    private byte[] doHandshake1(byte[] responseData) throws SaslException {

        try {

            // Security context already established. responseData

            // should contain no data

            if (responseData != null && responseData.length > 0) {

                throw new SaslException(

                    "Handshake expecting no response data from server");

            }

            // Construct 4 octets of data:

            // First octet contains bitmask specifying protections supported

            // 2nd-4th octets contains max receive buffer of server

            byte[] gssInToken = new byte[4];

            gssInToken[0] = allQop;

            intToNetworkByteOrder(recvMaxBufSize, gssInToken, 1, 3);

            if (logger.isLoggable(Level.FINE)) {

                logger.log(Level.FINE,

                    "KRB5SRV06:Supported protections: {0}; recv max buf size: {1}",

                    new Object[]{allQop,

                                 recvMaxBufSize});

            }

            handshakeStage = 2;  // progress to next stage

            if (logger.isLoggable(Level.FINER)) {

                traceOutput(MY_CLASS_NAME, "doHandshake1",

                    "KRB5SRV07:Challenge [raw]", gssInToken);

            }

            byte[] gssOutToken = secCtx.wrap(gssInToken, 0, gssInToken.length,

                new MessageProp(0 /* gop */, false /* privacy */));

            if (logger.isLoggable(Level.FINER)) {

                traceOutput(MY_CLASS_NAME, "doHandshake1",

                    "KRB5SRV08:Challenge [after wrap]", gssOutToken);

            }

            return gssOutToken;

        } catch (GSSException e) {

            throw new SaslException("Problem wrapping handshake1", e);

        }

    }

    private byte[] doHandshake2(byte[] responseData) throws SaslException {

        try {

            // Expecting 4 octets from client selected protection

            // and client's receive buffer size

            byte[] gssOutToken = secCtx.unwrap(responseData, 0,

                responseData.length, new MessageProp(0, false));

            if (logger.isLoggable(Level.FINER)) {

                traceOutput(MY_CLASS_NAME, "doHandshake2",

                    "KRB5SRV09:Response [after unwrap]", gssOutToken);

            }

            // First octet is a bit-mask specifying the selected protection

            byte selectedQop = gssOutToken[0];

            if ((selectedQop&allQop) == 0) {

                throw new SaslException("Client selected unsupported protection: "

                    + selectedQop);

            }

            if ((selectedQop&PRIVACY_PROTECTION) != 0) {

                privacy = true;

                integrity = true;

            } else if ((selectedQop&INTEGRITY_ONLY_PROTECTION) != 0) {

                integrity = true;

            }

            // 2nd-4th octets specifies maximum buffer size expected by

            // client (in network byte order). This is the server's send

            // buffer maximum.

            int clntMaxBufSize = networkByteOrderToInt(gssOutToken, 1, 3);

            // Determine the max send buffer size based on what the

            // client is able to receive and our specified max

            sendMaxBufSize = (sendMaxBufSize == 0) ? clntMaxBufSize :

                Math.min(sendMaxBufSize, clntMaxBufSize);

            // Update context to limit size of returned buffer

            rawSendSize = secCtx.getWrapSizeLimit(JGSS_QOP, privacy,

                sendMaxBufSize);

            if (logger.isLoggable(Level.FINE)) {

                logger.log(Level.FINE,

            "KRB5SRV10:Selected protection: {0}; privacy: {1}; integrity: {2}",

                    new Object[]{selectedQop,

                                 Boolean.valueOf(privacy),

                                 Boolean.valueOf(integrity)});

                logger.log(Level.FINE,

"KRB5SRV11:Client max recv size: {0}; server max send size: {1}; rawSendSize: {2}",

                    new Object[] {clntMaxBufSize,

                                  sendMaxBufSize,

                                  rawSendSize});

            }

            // Get authorization identity, if any

            if (gssOutToken.length > 4) {

                try {

                    authzid = new String(gssOutToken, 4,

                        gssOutToken.length - 4, "UTF-8");

                } catch (UnsupportedEncodingException uee) {

                    throw new SaslException ("Cannot decode authzid", uee);

                }

            } else {

                authzid = peer;

            }

            logger.log(Level.FINE, "KRB5SRV12:Authzid: {0}", authzid);

            AuthorizeCallback acb = new AuthorizeCallback(peer, authzid);

            // In Kerberos, realm is embedded in peer name

            cbh.handle(new Callback[] {acb});

            if (acb.isAuthorized()) {

                authzid = acb.getAuthorizedID();

                completed = true;

            } else {

                // Authorization failed

                throw new SaslException(peer +

                    " is not authorized to connect as " + authzid);

            }

            return null;

        } catch (GSSException e) {

            throw new SaslException("Final handshake step failed", e);

        } catch (IOException e) {

            throw new SaslException("Problem with callback handler", e);

        } catch (UnsupportedCallbackException e) {

            throw new SaslException("Problem with callback handler", e);

        }

    }

    public String getAuthorizationID() {

        if (completed) {

            return authzid;

        } else {

            throw new IllegalStateException("Authentication incomplete");

        }

    }

    public Object getNegotiatedProperty(String propName) {

        if (!completed) {

            throw new IllegalStateException("Authentication incomplete");

        }

        Object result;

        switch (propName) {

            case Sasl.BOUND_SERVER_NAME:

                try {

                    // me might take the form of proto@host or proto/host

                    result = me.split("[/@]")[1];

                } catch (Exception e) {

                    result = null;

                }

                break;

            default:

                result = super.getNegotiatedProperty(propName);

        }

        return result;

    }

}