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package sun.security.jgss.krb5;

import javax.security.auth.kerberos.KerberosTicket;
import javax.security.auth.kerberos.KerberosKey;
import javax.security.auth.kerberos.KerberosPrincipal;
import javax.security.auth.kerberos.KeyTab;
import javax.security.auth.Subject;
import javax.security.auth.login.LoginException;
import java.security.AccessControlContext;
import sun.security.jgss.GSSUtil;
import sun.security.jgss.GSSCaller;

import sun.security.krb5.Credentials;
import sun.security.krb5.EncryptionKey;
import sun.security.krb5.KrbException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import sun.security.krb5.KerberosSecrets;
import sun.security.krb5.PrincipalName;
Utilities for obtaining and converting Kerberos tickets.
/**
 * Utilities for obtaining and converting Kerberos tickets.
 *
 */
public class Krb5Util {

    static final boolean DEBUG =
        java.security.AccessController.doPrivileged(
            new sun.security.action.GetBooleanAction
            ("sun.security.krb5.debug")).booleanValue();

    
Default constructor
/**
     * Default constructor
     */
    private Krb5Util() {  // Cannot create one of these
    }

    
Retrieve the service ticket for serverPrincipal from caller's Subject
or from Subject obtained by logging in, or if not found, via the
Ticket Granting Service using the TGT obtained from the Subject.
Caller must have permission to:
   - access and update Subject's private credentials
   - create LoginContext
   - read the auth.login.defaultCallbackHandler security property
NOTE: This method is used by JSSE Kerberos Cipher Suites
/**
     * Retrieve the service ticket for serverPrincipal from caller's Subject
     * or from Subject obtained by logging in, or if not found, via the
     * Ticket Granting Service using the TGT obtained from the Subject.
     *
     * Caller must have permission to:
     *    - access and update Subject's private credentials
     *    - create LoginContext
     *    - read the auth.login.defaultCallbackHandler security property
     *
     * NOTE: This method is used by JSSE Kerberos Cipher Suites
     */
    public static KerberosTicket getTicketFromSubjectAndTgs(GSSCaller caller,
        String clientPrincipal, String serverPrincipal, String tgsPrincipal,
        AccessControlContext acc)
        throws LoginException, KrbException, IOException {

        // 1. Try to find service ticket in acc subject
        Subject accSubj = Subject.getSubject(acc);
        KerberosTicket ticket = SubjectComber.find(accSubj,
            serverPrincipal, clientPrincipal, KerberosTicket.class);

        if (ticket != null) {
            return ticket;  // found it
        }

        Subject loginSubj = null;
        if (!GSSUtil.useSubjectCredsOnly(caller)) {
            // 2. Try to get ticket from login
            try {
                loginSubj = GSSUtil.login(caller, GSSUtil.GSS_KRB5_MECH_OID);
                ticket = SubjectComber.find(loginSubj,
                    serverPrincipal, clientPrincipal, KerberosTicket.class);
                if (ticket != null) {
                    return ticket; // found it
                }
            } catch (LoginException e) {
                // No login entry to use
                // ignore and continue
            }
        }

        // Service ticket not found in subject or login
        // Try to get TGT to acquire service ticket

        // 3. Try to get TGT from acc subject
        KerberosTicket tgt = SubjectComber.find(accSubj,
            tgsPrincipal, clientPrincipal, KerberosTicket.class);

        boolean fromAcc;
        if (tgt == null && loginSubj != null) {
            // 4. Try to get TGT from login subject
            tgt = SubjectComber.find(loginSubj,
                tgsPrincipal, clientPrincipal, KerberosTicket.class);
            fromAcc = false;
        } else {
            fromAcc = true;
        }

        // 5. Try to get service ticket using TGT
        if (tgt != null) {
            Credentials tgtCreds = ticketToCreds(tgt);
            Credentials serviceCreds = Credentials.acquireServiceCreds(
                        serverPrincipal, tgtCreds);
            if (serviceCreds != null) {
                ticket = credsToTicket(serviceCreds);

                // Store service ticket in acc's Subject
                if (fromAcc && accSubj != null && !accSubj.isReadOnly()) {
                    accSubj.getPrivateCredentials().add(ticket);
                }
            }
        }
        return ticket;
    }

    
Retrieves the ticket corresponding to the client/server principal
pair from the Subject in the specified AccessControlContext.
/**
     * Retrieves the ticket corresponding to the client/server principal
     * pair from the Subject in the specified AccessControlContext.
     */
    static KerberosTicket getServiceTicket(GSSCaller caller,
        String clientPrincipal, String serverPrincipal,
        AccessControlContext acc) throws LoginException {

        // Try to get ticket from acc's Subject
        Subject accSubj = Subject.getSubject(acc);
        KerberosTicket ticket =
            SubjectComber.find(accSubj, serverPrincipal, clientPrincipal,
                  KerberosTicket.class);

        return ticket;
    }

    
Retrieves the initial TGT corresponding to the client principal
from the Subject in the specified AccessControlContext.
If the ticket can not be found in the Subject, and if
useSubjectCredsOnly is false, then obtain ticket from
a LoginContext.
/**
     * Retrieves the initial TGT corresponding to the client principal
     * from the Subject in the specified AccessControlContext.
     * If the ticket can not be found in the Subject, and if
     * useSubjectCredsOnly is false, then obtain ticket from
     * a LoginContext.
     */
    static KerberosTicket getInitialTicket(GSSCaller caller,
            String clientPrincipal,
            AccessControlContext acc) throws LoginException {

        // Try to get ticket from acc's Subject
        Subject accSubj = Subject.getSubject(acc);
        KerberosTicket ticket =
                SubjectComber.find(accSubj, null, clientPrincipal,
                        KerberosTicket.class);

        // Try to get ticket from Subject obtained from GSSUtil
        if (ticket == null && !GSSUtil.useSubjectCredsOnly(caller)) {
            Subject subject = GSSUtil.login(caller, GSSUtil.GSS_KRB5_MECH_OID);
            ticket = SubjectComber.find(subject,
                    null, clientPrincipal, KerberosTicket.class);
        }
        return ticket;
    }

    
Retrieves the caller's Subject, or Subject obtained by logging in
via the specified caller.
Caller must have permission to:
   - access the Subject
   - create LoginContext
   - read the auth.login.defaultCallbackHandler security property
NOTE: This method is used by JSSE Kerberos Cipher Suites
/**
     * Retrieves the caller's Subject, or Subject obtained by logging in
     * via the specified caller.
     *
     * Caller must have permission to:
     *    - access the Subject
     *    - create LoginContext
     *    - read the auth.login.defaultCallbackHandler security property
     *
     * NOTE: This method is used by JSSE Kerberos Cipher Suites
     */
    public static Subject getSubject(GSSCaller caller,
        AccessControlContext acc) throws LoginException {

        // Try to get the Subject from acc
        Subject subject = Subject.getSubject(acc);

        // Try to get Subject obtained from GSSUtil
        if (subject == null && !GSSUtil.useSubjectCredsOnly(caller)) {
            subject = GSSUtil.login(caller, GSSUtil.GSS_KRB5_MECH_OID);
        }
        return subject;
    }

    
Retrieves the ServiceCreds for the specified server principal from
the Subject in the specified AccessControlContext. If not found, and if
useSubjectCredsOnly is false, then obtain from a LoginContext.
NOTE: This method is also used by JSSE Kerberos Cipher Suites
/**
     * Retrieves the ServiceCreds for the specified server principal from
     * the Subject in the specified AccessControlContext. If not found, and if
     * useSubjectCredsOnly is false, then obtain from a LoginContext.
     *
     * NOTE: This method is also used by JSSE Kerberos Cipher Suites
     */
    public static ServiceCreds getServiceCreds(GSSCaller caller,
        String serverPrincipal, AccessControlContext acc)
                throws LoginException {

        Subject accSubj = Subject.getSubject(acc);
        ServiceCreds sc = null;
        if (accSubj != null) {
            sc = ServiceCreds.getInstance(accSubj, serverPrincipal);
        }
        if (sc == null && !GSSUtil.useSubjectCredsOnly(caller)) {
            Subject subject = GSSUtil.login(caller, GSSUtil.GSS_KRB5_MECH_OID);
            sc = ServiceCreds.getInstance(subject, serverPrincipal);
        }
        return sc;
    }

    public static KerberosTicket credsToTicket(Credentials serviceCreds) {
        EncryptionKey sessionKey =  serviceCreds.getSessionKey();
        KerberosTicket kt = new KerberosTicket(
            serviceCreds.getEncoded(),
            new KerberosPrincipal(serviceCreds.getClient().getName()),
            new KerberosPrincipal(serviceCreds.getServer().getName(),
                                KerberosPrincipal.KRB_NT_SRV_INST),
            sessionKey.getBytes(),
            sessionKey.getEType(),
            serviceCreds.getFlags(),
            serviceCreds.getAuthTime(),
            serviceCreds.getStartTime(),
            serviceCreds.getEndTime(),
            serviceCreds.getRenewTill(),
            serviceCreds.getClientAddresses());
        PrincipalName clientAlias = serviceCreds.getClientAlias();
        PrincipalName serverAlias = serviceCreds.getServerAlias();
        if (clientAlias != null) {
            KerberosSecrets.getJavaxSecurityAuthKerberosAccess()
                    .kerberosTicketSetClientAlias(kt, new KerberosPrincipal(
                            clientAlias.getName(), clientAlias.getNameType()));
        }
        if (serverAlias != null) {
            KerberosSecrets.getJavaxSecurityAuthKerberosAccess()
                    .kerberosTicketSetServerAlias(kt, new KerberosPrincipal(
                            serverAlias.getName(), serverAlias.getNameType()));
        }
        return kt;
    };

    public static Credentials ticketToCreds(KerberosTicket kerbTicket)
            throws KrbException, IOException {
        KerberosPrincipal clientAlias = KerberosSecrets
                .getJavaxSecurityAuthKerberosAccess()
                .kerberosTicketGetClientAlias(kerbTicket);
        KerberosPrincipal serverAlias = KerberosSecrets
                .getJavaxSecurityAuthKerberosAccess()
                .kerberosTicketGetServerAlias(kerbTicket);
        return new Credentials(
            kerbTicket.getEncoded(),
            kerbTicket.getClient().getName(),
            (clientAlias != null ? clientAlias.getName() : null),
            kerbTicket.getServer().getName(),
            (serverAlias != null ? serverAlias.getName() : null),
            kerbTicket.getSessionKey().getEncoded(),
            kerbTicket.getSessionKeyType(),
            kerbTicket.getFlags(),
            kerbTicket.getAuthTime(),
            kerbTicket.getStartTime(),
            kerbTicket.getEndTime(),
            kerbTicket.getRenewTill(),
            kerbTicket.getClientAddresses());
    }

    
A helper method to get a sun..KeyTab from a javax..KeyTab
Params:
ktab – the javax..KeyTab object
Returns:
the sun..KeyTab object/**
     * A helper method to get a sun..KeyTab from a javax..KeyTab
     * @param ktab the javax..KeyTab object
     * @return the sun..KeyTab object
     */
    public static sun.security.krb5.internal.ktab.KeyTab
            snapshotFromJavaxKeyTab(KeyTab ktab) {
        return KerberosSecrets.getJavaxSecurityAuthKerberosAccess()
                .keyTabTakeSnapshot(ktab);
    }

    
A helper method to get EncryptionKeys from a javax..KeyTab
Params:
ktab – the javax..KeyTab object
cname – the PrincipalName
Returns:
the EKeys, never null, might be empty/**
     * A helper method to get EncryptionKeys from a javax..KeyTab
     * @param ktab the javax..KeyTab object
     * @param cname the PrincipalName
     * @return the EKeys, never null, might be empty
     */
    public static EncryptionKey[] keysFromJavaxKeyTab(
            KeyTab ktab, PrincipalName cname) {
        return snapshotFromJavaxKeyTab(ktab).readServiceKeys(cname);
    }
}