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 /*
  * qca_securelayer.h - Qt Cryptographic Architecture
  * Copyright (C) 2003-2007  Justin Karneges <justin@affinix.com>
  * Copyright (C) 2004-2006  Brad Hards <bradh@frogmouth.net>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * This library 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  * 02110-1301  USA
  *
  */
 
 /**
    \file qca_securelayer.h
 
    Header file for SecureLayer and its subclasses
 
    \note You should not use this header directly from an
    application. You should just use <tt> \#include \<QtCrypto>
    </tt> instead.
 */
 #ifndef QCA_SECURELAYER_H
 #define QCA_SECURELAYER_H
 
 #include "qca_cert.h"
 #include "qca_core.h"
 #include "qca_publickey.h"
 #include <QObject>
 
 namespace QCA {
 
 /**
    Specify the lower-bound for acceptable TLS/SASL security layers
 
    For TLS, the interpretation of these levels is:
    - Any cipher suite that provides non-authenticated communications
    (usually anonymous Diffie-Hellman) is SL_Integrity.
    - Any cipher suite that is limited to 40 bits (export-version
    crippled forms of RC2, RC4 or DES) is SL_Export. Standard
    DES (56 bits) and some forms of RC4 (64 bits) are also SL_Export.
    - Any normal cipher (AES, Camellia, RC4 or similar) with 128 bits, or
    Elliptic Curve Ciphers with 283 bits, is SL_Baseline
    - AES or Camellia at least 192 bits, triple-DES and similar
    ciphers are SL_High.  ECC with 409 or more bits is also SL_High.
    - Highest does not have an equivalent strength. It
    indicates that the provider should use the strongest
    ciphers available (but not less than SL_High).
  */
 enum SecurityLevel
 {
     SL_None,      ///< indicates that no security is ok
     SL_Integrity, ///< must at least get integrity protection
     SL_Export,    ///< must be export level bits or more
     SL_Baseline,  ///< must be 128 bit or more
     SL_High,      ///< must be more than 128 bit
     SL_Highest    ///< SL_High or max possible, whichever is greater
 };
 
 /**
    \class SecureLayer qca_securelayer.h QtCrypto
 
    Abstract interface to a security layer
 
    SecureLayer is normally used between an application and a
    potentially insecure network. It provides secure
    communications over that network.
 
    The concept is that (after some initial setup), the
    application can write() some data to the SecureLayer
    implementation, and that data is encrypted (or otherwise
    protected, depending on the setup). The SecureLayer
    implementation then emits the readyReadOutgoing() signal,
    and the application uses readOutgoing() to retrieve the
    encrypted data from the SecureLayer implementation.  The
    encrypted data is then sent out on the network.
 
    When some encrypted data comes back from the network, the
    application does a writeIncoming() to the SecureLayer
    implementation. Some time later, the SecureLayer
    implementation may emit readyRead() to the application,
    which then read()s the decrypted data from the SecureLayer
    implementation.
 
    Note that sometimes data is sent or received between the
    SecureLayer implementation and the network without any data
    being sent between the application and the SecureLayer
    implementation. This is a result of the initial negotiation
    activities (which require network traffic to agree a
    configuration to use) and other overheads associated with
    the secure link.
 
    \ingroup UserAPI
 */
 class QCA_EXPORT SecureLayer : public QObject
 {
     Q_OBJECT
 public:
     /**
        Constructor for an abstract secure communications
        layer
 
        \param parent the parent object for this object
     */
     SecureLayer(QObject *parent = nullptr);
 
     /**
        Returns true if the layer has a meaningful "close".
     */
     virtual bool isClosable() const;
 
     /**
        Returns the number of bytes available to be read()
        on the application side.
     */
     virtual int bytesAvailable() const = 0;
 
     /**
        Returns the number of bytes available to be
        readOutgoing() on the network side.
     */
     virtual int bytesOutgoingAvailable() const = 0;
 
     /**
        Close the link. Note that this may not be
        meaningful / possible for all implementations.
 
        \sa isClosable() for a test that verifies if the
        link can be %closed.
     */
     virtual void close();
 
     /**
        This method writes unencrypted (plain) data to
        the SecureLayer implementation. You normally
        call this function on the application side.
 
        \param a the source of the application-side data
     */
     virtual void write(const QByteArray &a) = 0;
 
     /**
        This method reads decrypted (plain) data from
        the SecureLayer implementation. You normally call
        this function on the application side after receiving
        the readyRead() signal.
     */
     virtual QByteArray read() = 0;
 
     /**
        This method accepts encoded (typically encrypted) data
        for processing. You normally call this function using
        data read from the network socket (e.g. using
        QTcpSocket::readAll()) after receiving a signal that
        indicates that the socket has data to read.
 
        \param a the ByteArray to take network-side data from
     */
     virtual void writeIncoming(const QByteArray &a) = 0;
 
     /**
        This method provides encoded (typically encrypted)
        data. You normally call this function to get data
        to write out to the network socket (e.g. using
        QTcpSocket::write()) after receiving the
        readyReadOutgoing() signal.
 
        \param plainBytes the number of bytes that were read.
     */
     virtual QByteArray readOutgoing(int *plainBytes = nullptr) = 0;
 
     /**
        This allows you to read data without having it
        decrypted first. This is intended to be used for
        protocols that close off the connection and return
        to plain text transfer. You do not normally need to
        use this function.
     */
     virtual QByteArray readUnprocessed();
 
     /**
        Convert encrypted bytes written to plain text bytes written
 
        \param encryptedBytes the number of bytes to convert
     */
     virtual int convertBytesWritten(qint64 encryptedBytes) = 0;
 
 Q_SIGNALS:
     /**
        This signal is emitted when SecureLayer has
        decrypted (application side) data ready to be
        read. Typically you will connect this signal to a
        slot that reads the data (using read()).
     */
     void readyRead();
 
     /**
        This signal is emitted when SecureLayer has encrypted
        (network side) data ready to be read. Typically you
        will connect this signal to a slot that reads the data
        (using readOutgoing()) and writes it to a network socket.
     */
     void readyReadOutgoing();
 
     /**
        This signal is emitted when the SecureLayer connection
        is %closed.
     */
     void closed();
 
     /**
        This signal is emitted when an error is detected. You
        can determine the error type using errorCode().
     */
     void error();
 
 private:
     Q_DISABLE_COPY(SecureLayer)
 };
 
 /**
    \class TLSSession qca_securelayer.h QtCrypto
 
    Session token, used for TLS resuming
 
    \ingroup UserAPI
 
 */
 class QCA_EXPORT TLSSession : public Algorithm
 {
 public:
     TLSSession();
 
     /**
        Copy constructor
 
        \param from the session token to copy from
     */
     TLSSession(const TLSSession &from);
 
     ~TLSSession() override;
 
     /**
        Assignment operator
 
        \param from the session token to assign from
     */
     TLSSession &operator=(const TLSSession &from);
 
     /**
        Test if the session token is valid
     */
     bool isNull() const;
 };
 
 /**
    \class TLS qca_securelayer.h QtCrypto
 
    Transport Layer Security / Secure Socket Layer
 
    Transport Layer Security (%TLS) is the current
    state-of-the-art in secure transport mechanisms over the
    internet. It can be used in a way where only one side of
    the link needs to authenticate to the other. This makes it
    very useful for servers to provide their identity to
    clients. Note that is is possible to use %TLS to
    authenticate both client and server.
 
    %TLS is a IETF standard (<a
    href="http://www.ietf.org/rfc/rfc2712.txt">RFC2712</a> for
    TLS version 1.0, and <a
    href="http://www.ietf.org/rfc/rfc4346.txt">RFC4346</a> for
    TLS version 1.1) based on earlier Netscape work on Secure
    Socket Layer (SSL version 2 and SSL version 3). New
    applications should use at least TLS 1.0, and SSL version 2
    should be avoided due to known security problems.
 
    \ingroup UserAPI
 */
 class QCA_EXPORT TLS : public SecureLayer, public Algorithm
 {
     Q_OBJECT
 public:
     /**
        Operating mode
     */
     enum Mode
     {
         Stream,  ///< stream mode
         Datagram ///< datagram mode
     };
 
     /**
        Version of %TLS or SSL
     */
     enum Version
     {
         TLS_v1, ///< Transport Layer Security, version 1
         SSL_v3, ///< Secure Socket Layer, version 3
         SSL_v2, ///< Secure Socket Layer, version 2
         DTLS_v1 ///< Datagram Transport Layer Security, version 1
     };
 
     /**
        Type of error
     */
     enum Error
     {
         ErrorSignerExpired,   ///< local certificate is expired
         ErrorSignerInvalid,   ///< local certificate is invalid in some way
         ErrorCertKeyMismatch, ///< certificate and private key don't match
         ErrorInit,            ///< problem starting up %TLS
         ErrorHandshake,       ///< problem during the negotiation
         ErrorCrypt            ///< problem at anytime after
     };
 
     /**
        Type of identity
     */
     enum IdentityResult
     {
         Valid,              ///< identity is verified
         HostMismatch,       ///< valid cert provided, but wrong owner
         InvalidCertificate, ///< invalid cert
         NoCertificate       ///< identity unknown
     };
 
     /**
         Constructor for Transport Layer Security connection
 
         This produces a Stream (normal %TLS) rather than Datagram (DTLS)
         object.
         If you want to do DTLS, see below.
 
         \param parent the parent object for this object
         \param provider the name of the provider, if a specific provider
         is required
     */
     explicit TLS(QObject *parent = nullptr, const QString &provider = QString());
 
     /**
        Constructor for Transport Layer Security connection.
 
        This constructor can be used for both normal %TLS (set mode to TLS::Stream)
        or DTLS (set mode to TLS::Datagram).
 
        \param mode the connection Mode
        \param parent the parent object for this object
        \param provider the name of the provider, if a specific provider is
        required
     */
     explicit TLS(Mode mode, QObject *parent = nullptr, const QString &provider = QString());
 
     /**
        Destructor
     */
     ~TLS() override;
 
     /**
        Reset the connection
     */
     void reset();
 
     /**
        Get the list of cipher suites that are available for use.
 
        A cipher suite is a combination of key exchange,
        encryption and hashing algorithms that are agreed
        during the initial handshake between client and
        server.
 
        \param version the protocol Version that the cipher
        suites are required for
 
        \return list of the names of the cipher suites
        supported.
     */
     QStringList supportedCipherSuites(const Version &version = TLS_v1) const;
 
     /**
        The local certificate to use. This is the
        certificate that will be provided to the peer. This
        is almost always required on the server side
        (because the server has to provide a certificate to
        the client), and may be used on the client side.
 
        \param cert a chain of certificates that
        link the host certificate to a trusted root
        certificate.
        \param key the private key for the certificate
        chain
     */
     void setCertificate(const CertificateChain &cert, const PrivateKey &key);
 
     /**
        \overload
 
        Allows setting a certificate from a KeyBundle.
 
        \param kb key bundle containing the local certificate
        and associated private key.
     */
     void setCertificate(const KeyBundle &kb);
 
     /**
        Return the trusted certificates set for this object
     */
     CertificateCollection trustedCertificates() const;
 
     /**
        Set up the set of trusted certificates that will be used to verify
        that the certificate provided is valid.
 
        Typically, this will be the collection of root certificates from
        the system, which you can get using QCA::systemStore(), however you
        may choose to pass whatever certificates match your assurance
        needs.
 
        \param trusted a bundle of trusted certificates.
     */
     void setTrustedCertificates(const CertificateCollection &trusted);
 
     /**
        The security level required for this link
 
        \param s the level required for this link.
     */
     void setConstraints(SecurityLevel s);
 
     /**
        \overload
 
        \param minSSF the minimum Security Strength Factor
        required for this link.
        \param maxSSF the maximum Security Strength Factor
        required for this link.
     */
     void setConstraints(int minSSF, int maxSSF);
 
     /**
        \overload
 
        \param cipherSuiteList a list of the names of
        cipher suites that can be used for this link.
 
        \note the names are the same as the names in the
        applicable IETF RFCs (or Internet Drafts if there
        is no applicable RFC).
     */
     void setConstraints(const QStringList &cipherSuiteList);
 
     /**
        Retrieve the list of allowed issuers by the server,
        if the server has provided them.  Only DN types will
        be present.
 
        \code
 Certificate someCert = ...
 PrivateKey someKey = ...
 
 // see if the server will take our cert
 CertificateInfoOrdered issuerInfo = someCert.issuerInfoOrdered().dnOnly();
 foreach(const CertificateInfoOrdered &info, tls->issuerList())
 {
     if(info == issuerInfo)
     {
         // server will accept someCert, let's present it
         tls->setCertificate(someCert, someKey);
         break;
     }
 }
        \endcode
     */
     QList<CertificateInfoOrdered> issuerList() const;
 
     /**
        Sets the issuer list to present to the client.  For
        use with servers only.  Only DN types are allowed.
 
        \param issuers the list of valid issuers to be used.
     */
     void setIssuerList(const QList<CertificateInfoOrdered> &issuers);
 
     /**
        Resume a %TLS session using the given session object
 
        \param session the session state to use for resumption.
     */
     void setSession(const TLSSession &session);
 
     /**
        Test if the link can use compression
 
        \return true if the link can use compression
     */
     bool canCompress() const;
 
     /**
        Test if the link can specify a hostname (Server Name
        Indication)
 
        \return true if the link can specify a hostname
     */
     bool canSetHostName() const;
 
     /**
        Returns true if compression is enabled
 
        This only indicates whether or not the object is configured to use
        compression, not whether or not the link is actually compressed.
        Use isCompressed() for that.
     */
     bool compressionEnabled() const;
 
     /**
        Set the link to use compression
 
        \param b true if the link should use compression, or false to
        disable compression
     */
     void setCompressionEnabled(bool b);
 
     /**
        Returns the host name specified or an empty string if no host
        name is specified.
     */
     QString hostName() const;
 
     /**
        Start the %TLS/SSL connection as a client
 
        Typically, you'll want to perform RFC 2818 validation on the
        server's certificate, based on the hostname you're intending
        to connect to.  Pass a value for \a host in order to have the
        validation for you.  If you want to bypass this behavior and
        do the validation yourself, pass an empty string for \a host.
 
        If the host is an internationalized domain name, then it must be
        provided in unicode format, not in IDNA ACE/punycode format.
 
        \param host the hostname that you want to connect to
 
        \note The hostname will be used for Server Name Indication
        extension (see
        <a href="http://www.ietf.org/rfc/rfc3546.txt">RFC 3546</a> Section
        3.1) if supported by the backend provider.
     */
     void startClient(const QString &host = QString());
 
     /**
        Start the %TLS/SSL connection as a server.
     */
     void startServer();
 
     /**
        Resumes %TLS processing.
 
        Call this function after hostNameReceived(), certificateRequested()
        peerCertificateAvailable() or handshaken() is emitted.  By
        requiring this function to be called in order to proceed,
        applications are given a chance to perform user interaction between
        steps in the %TLS process.
     */
     void continueAfterStep();
 
     /**
        test if the handshake is complete
 
        \return true if the handshake is complete
 
        \sa handshaken
     */
     bool isHandshaken() const;
 
     /**
        test if the link is compressed
 
        \return true if the link is compressed
     */
     bool isCompressed() const;
 
     /**
        The protocol version that is in use for this connection.
     */
     Version version() const;
 
     /**
        The cipher suite that has been negotiated for this connection.
 
        The name returned here is the name used in the applicable RFC
        (or Internet Draft, where there is no RFC).
     */
     QString cipherSuite() const;
 
     /**
        The number of effective bits of security being used for this
        connection.
 
        This can differ from the actual number of bits in
        the cipher for certain
        older "export ciphers" that are deliberately crippled. If you
        want that information, use cipherMaxBits().
     */
     int cipherBits() const;
 
     /**
        The number of bits of security that the cipher could use.
 
        This is normally the same as cipherBits(), but can be greater
        for older "export ciphers".
     */
     int cipherMaxBits() const;
 
     /**
        The session object of the %TLS connection, which can be used
        for resuming.
     */
     TLSSession session() const;
 
     /**
        This method returns the type of error that has
        occurred. You should only need to check this if the
        error() signal is emitted.
     */
     Error errorCode() const;
 
     /**
        After the SSL/%TLS handshake is complete, this
        method allows you to determine if the other end
        of the connection (if the application is a client,
        this is the server; if the application is a server,
        this is the client) has a valid identity.
 
        Note that the security of %TLS/SSL depends on
        checking this. It is not enough to check that the
        certificate is valid - you must check that the
        certificate is valid for the entity that you are
        trying to communicate with.
 
        \note If this returns QCA::TLS::InvalidCertificate,
        you may wish to use peerCertificateValidity() to
        determine whether to proceed or not.
     */
     IdentityResult peerIdentityResult() const;
 
     /**
        After the SSL/%TLS handshake is valid, this method
        allows you to check if the received certificate
        from the other end is valid. As noted in
        peerIdentityResult(), you also need to check that
        the certificate matches the entity you are trying
        to communicate with.
     */
     Validity peerCertificateValidity() const;
 
     /**
        The CertificateChain for the local host
        certificate.
     */
     CertificateChain localCertificateChain() const;
 
     /**
        The PrivateKey for the local host
        certificate.
     */
     PrivateKey localPrivateKey() const;
 
     /**
        The CertificateChain from the peer (other end of
        the connection to the trusted root certificate).
     */
     CertificateChain peerCertificateChain() const;
 
     // reimplemented
     bool       isClosable() const override;
     int        bytesAvailable() const override;
     int        bytesOutgoingAvailable() const override;
     void       close() override;
     void       write(const QByteArray &a) override;
     QByteArray read() override;
     void       writeIncoming(const QByteArray &a) override;
     QByteArray readOutgoing(int *plainBytes = nullptr) override;
     QByteArray readUnprocessed() override;
     int        convertBytesWritten(qint64 encryptedBytes) override;
 
     /**
        Determine the number of packets available to be
        read on the application side.
 
        \note this is only used with DTLS.
     */
     int packetsAvailable() const;
 
     /**
        Determine the number of packets available to be
        read on the network side.
 
        \note this is only used with DTLS.
     */
     int packetsOutgoingAvailable() const;
 
     /**
        Return the currently configured maximum packet size
 
        \note this is only used with DTLS
     */
     int packetMTU() const;
 
     /**
        Set the maximum packet size to use.
 
        \param size the number of bytes to set as the MTU.
 
        \note this is only used with DTLS.
     */
     void setPacketMTU(int size) const;
 
 Q_SIGNALS:
     /**
        Emitted if a host name is set by the client.  At
        this time, the server can inspect the hostName().
 
        You must call continueAfterStep() in order for %TLS
        processing to resume after this signal is emitted.
 
        This signal is only emitted in server mode.
 
        \sa continueAfterStep
     */
     void hostNameReceived();
 
     /**
        Emitted when the server requests a certificate.  At
        this time, the client can inspect the issuerList().
 
        You must call continueAfterStep() in order for %TLS
        processing to resume after this signal is emitted.
 
        This signal is only emitted in client mode.
 
        \sa continueAfterStep
     */
     void certificateRequested();
 
     /**
        Emitted when a certificate is received from the peer.
        At this time, you may inspect peerIdentityResult(),
        peerCertificateValidity(), and peerCertificateChain().
 
        You must call continueAfterStep() in order for %TLS
        processing to resume after this signal is emitted.
 
        \sa continueAfterStep
     */
     void peerCertificateAvailable();
 
     /**
        Emitted when the protocol handshake is complete.  At
        this time, all available information about the %TLS
        session can be inspected.
 
        You must call continueAfterStep() in order for %TLS
        processing to resume after this signal is emitted.
 
        \sa continueAfterStep
        \sa isHandshaken
     */
     void handshaken();
 
 protected:
     /**
        Called when a connection is made to a particular signal
 
        \param signal the name of the signal that has been
        connected to.
     */
     void connectNotify(const QMetaMethod &signal) override;
 
     /**
        Called when a connection is removed from a particular signal
 
        \param signal the name of the signal that has been
        disconnected from.
     */
     void disconnectNotify(const QMetaMethod &signal) override;
 
 private:
     Q_DISABLE_COPY(TLS)
 
     class Private;
     friend class Private;
     Private *d;
 };
 
 /**
    \class SASL qca_securelayer.h QtCrypto
 
    Simple Authentication and Security Layer protocol implementation
 
    This class implements the Simple Authenication and Security Layer protocol,
    which is described in RFC2222 - see
    <a href="http://www.ietf.org/rfc/rfc2222.txt">http://www.ietf.org/rfc/rfc2222.txt</a>.
 
    As the name suggests, %SASL provides authentication (eg, a "login" of some
    form), for a connection oriented protocol, and can also provide protection
    for the subsequent connection.
 
    The %SASL protocol is designed to be extensible, through a range of
    "mechanisms", where a mechanism is the actual authentication method.
    Example mechanisms include Anonymous, LOGIN, Kerberos V4, and GSSAPI.
    Mechanisms can be added (potentially without restarting the server
    application) by the system administrator.
 
    It is important to understand that %SASL is neither "network aware" nor
    "protocol aware".  That means that %SASL does not understand how the client
    connects to the server, and %SASL does not understand the actual
    application protocol.
 
    \ingroup UserAPI
 
 */
 class QCA_EXPORT SASL : public SecureLayer, public Algorithm
 {
     Q_OBJECT
 public:
     /**
        Possible errors that may occur when using %SASL
     */
     enum Error
     {
         ErrorInit,      ///< problem starting up %SASL
         ErrorHandshake, ///< problem during the authentication process
         ErrorCrypt      ///< problem at anytime after
     };
 
     /**
        Possible authentication error states
     */
     enum AuthCondition
     {
         AuthFail,         ///< Generic authentication failure
         NoMechanism,      ///< No compatible/appropriate authentication mechanism
         BadProtocol,      ///< Bad protocol or cancelled
         BadServer,        ///< Server failed mutual authentication (client side only)
         BadAuth,          ///< Authentication failure (server side only)
         NoAuthzid,        ///< Authorization failure (server side only)
         TooWeak,          ///< Mechanism too weak for this user (server side only)
         NeedEncrypt,      ///< Encryption is needed in order to use mechanism (server side only)
         Expired,          ///< Passphrase expired, has to be reset (server side only)
         Disabled,         ///< Account is disabled (server side only)
         NoUser,           ///< User not found (server side only)
         RemoteUnavailable ///< Remote service needed for auth is gone (server side only)
     };
 
     /**
        Authentication requirement flag values
     */
     enum AuthFlags
     {
         AuthFlagsNone          = 0x00,
         AllowPlain             = 0x01,
         AllowAnonymous         = 0x02,
         RequireForwardSecrecy  = 0x04,
         RequirePassCredentials = 0x08,
         RequireMutualAuth      = 0x10,
         RequireAuthzidSupport  = 0x20 // server-only
     };
 
     /**
        Mode options for client side sending
     */
     enum ClientSendMode
     {
         AllowClientSendFirst,
         DisableClientSendFirst
     };
 
     /**
        Mode options for server side sending
     */
     enum ServerSendMode
     {
         AllowServerSendLast,
         DisableServerSendLast
     };
 
     /**
        \class Params qca_securelayer.h QtCrypto
 
        Parameter flags for the %SASL authentication
 
        This is used to indicate which parameters are needed by %SASL
        in order to complete the authentication process.
 
        \ingroup UserAPI
     */
     class QCA_EXPORT Params
     {
     public:
         Params();
 
         /**
            Standard constructor.
 
            The concept behind this is that you set each of the
            flags depending on which parameters are needed.
 
            \param user the username is required
            \param authzid the authorization identity is required
            \param pass the password is required
            \param realm the realm is required
         */
         Params(bool user, bool authzid, bool pass, bool realm);
 
         /**
            Standard copy constructor
 
            \param from the Params object to copy
         */
         Params(const Params &from);
         ~Params();
 
         /**
            Standard assignment operator
 
            \param from the Params object to assign from
         */
         Params &operator=(const Params &from);
 
         /**
            User is needed
         */
         bool needUsername() const;
 
         /**
            An Authorization ID can be sent if desired
         */
         bool canSendAuthzid() const;
 
         /**
            Password is needed
         */
         bool needPassword() const;
 
         /**
            A Realm can be sent if desired
         */
         bool canSendRealm() const;
 
     private:
         class Private;
         Private *d;
     };
 
     /**
        Standard constructor
 
        \param parent the parent object for this %SASL connection
        \param provider if specified, the provider to use. If not
        specified, or specified as empty, then any provider is
        acceptable.
     */
     explicit SASL(QObject *parent = nullptr, const QString &provider = QString());
 
     ~SASL() override;
 
     /**
        Reset the %SASL mechanism
     */
     void reset();
 
     /**
        Specify connection constraints
 
        %SASL supports a range of authentication requirements, and
        a range of security levels. This method allows you to
        specify the requirements for your connection.
 
        \param f the authentication requirements, which you typically
        build using a binary OR function (eg AllowPlain | AllowAnonymous)
        \param s the security level of the encryption, if used. See
        SecurityLevel for details of what each level provides.
     */
     void setConstraints(AuthFlags f, SecurityLevel s = SL_None);
 
     /**
        \overload
 
        Unless you have a specific reason for directly specifying a
        strength factor, you probably should use the method above.
 
        \param f the authentication requirements, which you typically
        build using a binary OR function (eg AllowPlain | AllowAnonymous)
        \param minSSF the minimum security strength factor that is required
        \param maxSSF the maximum security strength factor that is required
 
        \note Security strength factors are a rough approximation to key
        length in the encryption function (eg if you are securing with
        plain DES, the security strength factor would be 56).
     */
     void setConstraints(AuthFlags f, int minSSF, int maxSSF);
 
     /**
        Specify the local address.
 
        \param addr the address of the local part of the connection
        \param port the port number of the local part of the connection
     */
     void setLocalAddress(const QString &addr, quint16 port);
 
     /**
        Specify the peer address.
 
        \param addr the address of the peer side of the connection
        \param port the port number of the peer side of the connection
     */
     void setRemoteAddress(const QString &addr, quint16 port);
 
     /**
        Specify the id of the externally secured connection
 
        \param authid the id of the connection
     */
     void setExternalAuthId(const QString &authid);
 
     /**
        Specify a security strength factor for an externally secured
        connection
 
        \param strength the security strength factor of the connection
     */
     void setExternalSSF(int strength);
 
     /**
        Initialise the client side of the connection
 
        startClient must be called on the client side of the connection.
        clientStarted will be emitted when the operation is completed.
 
        \param service the name of the service
        \param host the client side host name
        \param mechlist the list of mechanisms which can be used
        \param mode the mode to use on the client side
     */
     void startClient(const QString     &service,
                      const QString     &host,
                      const QStringList &mechlist,
                      ClientSendMode     mode = AllowClientSendFirst);
 
     /**
        Initialise the server side of the connection
 
        startServer must be called on the server side of the connection.
        serverStarted will be emitted when the operation is completed.
 
        \param service the name of the service
        \param host the server side host name
        \param realm the realm to use
        \param mode which mode to use on the server side
     */
     void startServer(const QString &service,
                      const QString &host,
                      const QString &realm,
                      ServerSendMode mode = DisableServerSendLast);
 
     /**
        Process the first step in server mode (server)
 
        Call this with the mechanism selected by the client.  If there
        is initial client data, call the other version of this function
        instead.
 
        \param mech the mechanism to be used.
     */
     void putServerFirstStep(const QString &mech);
 
     /**
        Process the first step in server mode (server)
 
        Call this with the mechanism selected by the client, and initial
        client data.  If there is no initial client data, call the other
        version of this function instead.
 
        \param mech the mechanism to be used
        \param clientInit the initial data provided by the client side
     */
     void putServerFirstStep(const QString &mech, const QByteArray &clientInit);
 
     /**
        Process an authentication step
 
        Call this with authentication data received from the network.
        The only exception is the first step in server mode, in which
        case putServerFirstStep must be called.
 
        \param stepData the authentication data from the network
     */
     void putStep(const QByteArray &stepData);
 
     /**
        Return the mechanism selected (client)
     */
     QString mechanism() const;
 
     /**
        Return the mechanism list (server)
     */
     QStringList mechanismList() const;
 
     /**
        Return the realm list, if available (client)
     */
     QStringList realmList() const;
 
     /**
        Return the security strength factor of the connection
     */
     int ssf() const;
 
     /**
        Return the error code
     */
     Error errorCode() const;
 
     /**
        Return the reason for authentication failure
     */
     AuthCondition authCondition() const;
 
     /**
        Specify the username to use in authentication
 
        \param user the username to use
     */
     void setUsername(const QString &user);
 
     /**
        Specify the authorization identity to use in authentication
 
        \param auth the authorization identity to use
     */
     void setAuthzid(const QString &auth);
 
     /**
        Specify the password to use in authentication
 
        \param pass the password to use
     */
     void setPassword(const SecureArray &pass);
 
     /**
        Specify the realm to use in authentication
 
        \param realm the realm to use
     */
     void setRealm(const QString &realm);
 
     /**
        Continue negotiation after parameters have been set (client)
     */
     void continueAfterParams();
 
     /**
        Continue negotiation after auth ids have been checked (server)
     */
     void continueAfterAuthCheck();
 
     // reimplemented
     int        bytesAvailable() const override;
     int        bytesOutgoingAvailable() const override;
     void       write(const QByteArray &a) override;
     QByteArray read() override;
     void       writeIncoming(const QByteArray &a) override;
     QByteArray readOutgoing(int *plainBytes = nullptr) override;
     int        convertBytesWritten(qint64 encryptedBytes) override;
 
 Q_SIGNALS:
     /**
        This signal is emitted when the client has been successfully
        started
 
        \param clientInit true if the client should send an initial
        response to the server
        \param clientInitData the initial response to send to the server.
        Do note that there is a difference in SASL between an empty initial
        response and no initial response, and so even if clientInitData is
        an empty array, you still need to send an initial response if
        clientInit is true.
     */
     void clientStarted(bool clientInit, const QByteArray &clientInitData);
 
     /**
        This signal is emitted after the server has been
        successfully started
     */
     void serverStarted();
 
     /**
        This signal is emitted when there is data required
        to be sent over the network to complete the next
        step in the authentication process.
 
        \param stepData the data to send over the network
     */
     void nextStep(const QByteArray &stepData);
 
     /**
        This signal is emitted when the client needs
        additional parameters
 
        After receiving this signal, the application should set
        the required parameter values appropriately and then call
        continueAfterParams().
 
        \param params the parameters that are required by the client
     */
     void needParams(const QCA::SASL::Params &params);
 
     /**
        This signal is emitted when the server needs to
        perform the authentication check
 
        If the user and authzid are valid, call continueAfterAuthCheck().
 
        \param user the user identification name
        \param authzid the user authorization name
     */
     void authCheck(const QString &user, const QString &authzid);
 
     /**
        This signal is emitted when authentication is complete.
     */
     void authenticated();
 
 private:
     Q_DISABLE_COPY(SASL)
 
     class Private;
     friend class Private;
     Private *d;
 };
 
 }
 
 #endif