/*  -*- C++ -*-
 *  Copyright (C) 2003,2005 Thiago Macieira <thiago@kde.org>
 *
 *
 *  Permission is hereby granted, free of charge, to any person obtaining
 *  a copy of this software and associated documentation files (the
 *  "Software"), to deal in the Software without restriction, including
 *  without limitation the rights to use, copy, modify, merge, publish,
 *  distribute, sublicense, and/or sell copies of the Software, and to
 *  permit persons to whom the Software is furnished to do so, subject to
 *  the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included
 *  in all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/*
 * Even before our #ifdef, clean up the namespace
 */
#ifdef socket
#undef socket
#endif

#ifdef bind
#undef bind
#endif

#ifdef listen
#undef listen
#endif

#ifdef connect
#undef connect
#endif

#ifdef accept
#undef accept
#endif

#ifdef getpeername
#undef getpeername
#endif

#ifdef getsockname
#undef getsockname
#endif

#ifndef KSOCKETBASE_H
#define KSOCKETBASE_H

#include <QtCore/QIODevice>
#include <QtCore/QString>

#include <kdelibs4support_export.h>
#include "k3socketaddress.h"

class QMutex;

namespace KNetwork
{

class KResolverEntry;
class KSocketDevice;

class KSocketBasePrivate;
/** @class KSocketBase k3socketbase.h k3socketbase.h
 *  @brief Basic socket functionality.
 *
 * This class provides the basic socket functionlity for descended classes.
 * Socket classes are thread-safe and provide a recursive mutex should it be
 * needed.
 *
 * @note This class is abstract.
 *
 * @author Thiago Macieira <thiago@kde.org>
 * @deprecated Use KSocketFactory or KLocalSocket instead
 */
class KDELIBS4SUPPORT_DEPRECATED_EXPORT KSocketBase
{
public:
    /**
     * Possible socket options.
     *
     * These are the options that may be set on a socket:
     *  - Blocking: whether the socket shall operate in blocking
     *    or non-blocking mode. This flag defaults to on.
     *    See setBlocking().
     *  - AddressReusable: whether the address used by this socket will
     *    be available for reuse by other sockets. This flag defaults to off.
     *    See setAddressReuseable().
     *  - IPv6Only: whether an IPv6 socket will accept IPv4 connections
     *    through a mapped address. This flag defaults to off.
     *    See setIPv6Only().
     *  - KeepAlive: whether TCP should send keepalive probes when a connection
     *    has gone idle for far too long.
     *  - Broadcast: whether this socket is allowed to send broadcast packets
     *    and will receive packets sent to broadcast.
     *  - NoDelay: disable the Nagle algorithm for socket types that support
     *    it.
     */
    enum SocketOptions {
        Blocking = 0x01,
        AddressReuseable = 0x02,
        IPv6Only = 0x04,
        Keepalive = 0x08,
        Broadcast = 0x10,
        NoDelay = 0x20
    };

    /**
     * Possible socket error codes.
     *
     * This is a list of possible error conditions that socket classes may
     * be expected to find.
     *
     * - NoError: no error has been detected
     * - LookupFailure: if a name lookup has failed
     * - AddressInUse: address is already in use
     * - AlreadyBound: cannot bind again
     * - AlreadyCreated: cannot recreate the socket
     * - NotBound: operation required socket to be bound and it isn't
     * - NotCreated: operation required socket to exist and it doesn't
     * - WouldBlock: requested I/O operation would block
     * - ConnectionRefused: connection actively refused
     * - ConnectionTimedOut: connection timed out
     * - InProgress: operation (connection) is already in progress
     * - NetFailure: a network failure occurred (no route, host down, host unreachable or similar)
     * - NotSupported: requested operation is not supported
     * - Timeout: a timed operation timed out
     * - UnknownError: an unknown/unexpected error has happened
     * - RemotelyDisconnected: when a connection is disconnected by the other end (since 3.4)
     *
     * @sa error, errorString
     */
    enum SocketError {
        NoError = 0,
        LookupFailure,
        AddressInUse,
        AlreadyCreated,
        AlreadyBound,
        AlreadyConnected,
        NotConnected,
        NotBound,
        NotCreated,
        WouldBlock,
        ConnectionRefused,
        ConnectionTimedOut,
        InProgress,
        NetFailure,
        NotSupported,
        Timeout,
        UnknownError,
        RemotelyDisconnected
    };

public:
    /**
     * Default constructor.
     */
    KSocketBase();

    /**
     * Destructor.
     */
    virtual ~KSocketBase();

    /*
     * The following functions are shared by all descended classes and will have
     * to be reimplemented.
     */

protected:
    /**
     * Set the given socket options.
     *
     * The default implementation does nothing but store the mask internally.
     * Descended classes must override this function to achieve functionality and
     * must also call this implementation.
     *
     * @param opts    a mask of SocketOptions or-ed bits of options to set
     *            or unset
     * @returns true on success
     * @note this function sets the options corresponding to the bits enabled in @p opts
     *       but will also unset the optiosn corresponding to the bits not set.
     */
    virtual bool setSocketOptions(int opts);

    /**
     * Retrieves the socket options that have been set.
     *
     * The default implementation just retrieves the mask from an internal variable.
     * Descended classes may choose to override this function to read the values
     * from the operating system.
     *
     * @returns the mask of the options set
     */
    virtual int socketOptions() const;

public:
    /**
     * Sets this socket's blocking mode.
     *
     * In blocking operation, all I/O functions are susceptible to blocking --
     * i.e., will not return unless the I/O can be satisfied. In non-blocking
     * operation, if the I/O would block, the function will return an error
     * and set the corresponding error code.
     *
     * The default implementation toggles the Blocking flag with the current
     * socket options and calls setSocketOptions().
     *
     * @param enable      whether to set this socket to blocking mode
     * @returns whether setting this value was successful; it is NOT the
     *          final blocking mode.
     */
    virtual bool setBlocking(bool enable);

    /**
     * Retrieves this socket's blocking mode.
     *
     * @returns true if this socket is/will be operated in blocking mode,
     *          false if non-blocking.
     */
    bool blocking() const;

    /**
     * Sets this socket's address reuseable flag.
     *
     * When the address reuseable flag is active, the address used by
     * this socket is left reuseable for other sockets to bind. If
     * the flag is not active, no other sockets may reuse the same
     * address.
     *
     * The default implementation toggles the AddressReuseable flag with the current
     * socket options and calls setSocketOptions().
     *
     * @param enable      whether to set the flag on or off
     * @returns true if setting this flag was successful
     */
    virtual bool setAddressReuseable(bool enable);

    /**
     * Retrieves this socket's address reuseability flag.
     *
     * @returns true if this socket's address can be reused,
     *          false if it can't.
     */
    bool addressReuseable() const;

    /**
     * Sets this socket's IPv6 Only flag.
     *
     * When this flag is on, an IPv6 socket will only accept, connect, send to or
     * receive from IPv6 addresses. When it is off, it will also talk to
     * IPv4 addresses through v4-mapped addresses.
     *
     * This option has no effect on non-IPv6 sockets.
     *
     * The default implementation toggles the IPv6Only flag with the current
     * socket options and calls setSocketOptions().
     *
     * @param enable      whether to set the flag on or off
     * @returns true if setting this flag was successful
     */
    virtual bool setIPv6Only(bool enable);

    /**
     * Retrieves this socket's IPv6 Only flag.
     *
     * @returns true if this socket will ignore IPv4-compatible and IPv4-mapped
     *          addresses, false if it will accept them.
     */
    bool isIPv6Only() const;

    /**
     * Sets this socket Broadcast flag.
     *
     * Datagram-oriented sockets cannot normally send packets to broadcast
     * addresses, nor will they receive packets that were sent to a broadcast
     * address. To do so, you need to enable the Broadcast flag.
     *
     * This option has no effect on stream-oriented sockets.
     *
     * @returns true if setting this flag was successful.
     */
    virtual bool setBroadcast(bool enable);

    /**
     * Retrieves this socket's Broadcast flag.
     *
     * @returns true if this socket can send and receive broadcast packets,
     *          false if it can't.
     */
    bool broadcast() const;

    /**
     * Sets this socket's NoDelay flag.
     *
     * Stream-oriented protocols, like TCP, have an internal algorithm
     * (called Nagle's algorithm) that collects data in a buffer so that
     * the transmission doesn't occur after every single write operation.
     * The side-effect is that the transmission of short messages is
     * delayed.
     *
     * Setting NoDelay to 'true' will disable this algorithm.
     *
     * @returns true if setting this flag was successful.
     */
    virtual bool setNoDelay(bool enable);

    /**
     * Retrieves this socket's NoDelay flag.
     *
     * @returns true if this socket's Nagle algorithm is disabled.
     */
    bool noDelay() const;

    /**
     * Retrieves the socket implementation used on this socket.
     *
     * This function creates the device if none has been set
     * using the default factory.
     */
    KSocketDevice *socketDevice() const;

    /**
     * Sets the socket implementation to be used on this socket.
     *
     * Note: it is an error to set this if the socket device has
     * already been set once.
     *
     * This function is provided virtual so that derived classes can catch
     * the setting of a device and properly set their own states and internal
     * variables. The parent class must be called.
     *
     * This function is called by socketDevice() above when the socket is
     * first created.
     */
    virtual void setSocketDevice(KSocketDevice *device);

    /**
     * Sets the internally requested capabilities for a socket device.
     *
     * Most socket classes can use any back-end implementation. However, a few
     * may require specific capabilities not provided in the default
     * implementation. By using this function, derived classes can request
     * that a backend with those capabilities be created when necessary.
     *
     * For the possible flags, see KSocketDevice::Capabilities. However, note
     * that only the Can* flags make sense in this context.
     *
     * @note Since socketDevice must always return a valid backend object, it
     *       is is possible that the created device does not conform to all
     *       requirements requested. Implementations sensitive to this fact
     *       should test the object returned by socketDevice() (through
     *       KSocketDevice::capabilities(), for instance) the availability.
     *
     * @param add     mask of KSocketDevice::Capabilities to add
     * @param remove  mask of bits to remove from the requirements
     * @return the current mask of requested capabilities
     */
    int setRequestedCapabilities(int add, int remove = 0);

protected:
    /**
     * Returns true if the socket device has been initialised in this
     * object, either by calling socketDevice() or setSocketDevice()
     */
    bool hasDevice() const;

    /**
     * Sets the socket's error code.
     *
     * @param error       the error code
     */
    void setError(SocketError error);

    /**
     * Resets the socket error code and the I/O Device's status.
     */
    void resetError();

public:
    /**
     * Retrieves the socket error code.
     * @sa errorString
     */
    SocketError error() const;

    /**
     * Returns the error string corresponding to this error condition.
     */
    QString errorString() const;

    /**
     * Returns the internal mutex for this class.
     *
     * Note on multithreaded use of sockets:
     * the socket classes are thread-safe by design, but you should be aware of
     * problems regarding socket creation, connection and destruction in
     * multi-threaded programs. The classes are guaranteed to work while
     * the socket exists, but it's not wise to call connect in multiple
     * threads.
     *
     * Also, this mutex must be unlocked before the object is destroyed, which
     * means you cannot use it to guard against other threads accessing the object
     * while destroying it. You must ensure there are no further references to this
     * object when deleting it.
     */
    QMutex *mutex() const;

public:
    /**
     * Returns the string describing the given error code, i18n'ed.
     *
     * @param code        the error code
     */
    static QString errorString(SocketError code);

    /**
     * Returns true if the given error code is a fatal one, false
     * otherwise. The parameter here is of type int so that
     * casting isn't necessary when using the parameter to signal
     * QClientSocketBase::gotError.
     *
     * @param code        the code to test
     */
    static bool isFatalError(int code);

private:
    /// @internal
    /// called by KSocketDevice
    void unsetSocketDevice();

    KSocketBase(const KSocketBase &);
    KSocketBase &operator =(const KSocketBase &);

    KSocketBasePrivate *const d;

    friend class KSocketDevice;
};

/**
 * @class KActiveSocketBase k3socketbase.h k3socketbase.h
 * @brief Abstract class for active sockets
 *
 * This class provides the standard interfaces for active sockets, i.e.,
 * sockets that are used to connect to external addresses.
 *
 * @author Thiago Macieira <thiago@kde.org>
 * @deprecated Use KSocketFactory or KLocalSocket instead
 */
class KDELIBS4SUPPORT_DEPRECATED_EXPORT KActiveSocketBase: public QIODevice, virtual public KSocketBase
{
    Q_OBJECT
public:
    /**
     * Constructor.
     */
    KActiveSocketBase(QObject *parent);

    /**
     * Destructor.
     */
    virtual ~KActiveSocketBase();

    /**
     * Unshadow errorString from QIODevice
     */
    QString errorString() const;

    /**
     * @reimp
     */
    void setSocketDevice(KSocketDevice *device) override;

    /**
     * Reimplemented from QIODevice.
     */
    bool open(OpenMode mode) override;

    /**
     * Binds this socket to the given address.
     *
     * The socket will be constructed with the address family,
     * socket type and protocol as those given in the
     * @p address object.
     *
     * @param address     the address to bind to
     * @returns true if the binding was successful, false otherwise
     */
    virtual bool bind(const KResolverEntry &address) = 0;

    /**
     * Connect to a remote host.
     *
     * This will make this socket try to connect to the remote host.
     * If the socket is not yet created, it will be created using the
     * address family, socket type and protocol specified in the
     * @p address object.
     *
     * If this function returns with error InProgress, calling it
     * again with the same address after a time will cause it to test
     * if the connection has succeeded in the mean time.
     *
     * @param address     the address to connect to
     * @param mode                mode for connection, from QIODevice
     *
     * @returns true if the connection was successful or has been successfully
     *          queued; false if an error occurred.
     */
    virtual bool connect(const KResolverEntry &address,
                         OpenMode mode = ReadWrite) = 0;

    /**
     * Disconnects this socket from a connection, if possible.
     *
     * If this socket was connected to an endpoint, the connection
     * is severed, but the socket is not closed. If the socket wasn't
     * connected, this function does nothing.
     *
     * If the socket hadn't yet been created, this function does nothing
     * either.
     *
     * Not all socket types can disconnect. Most notably, only
     * connectionless datagram protocols such as UDP support this operation.
     *
     * @return true if the socket is now disconnected or false on error.
     */
    virtual bool disconnect() = 0;

    /**
     * Sockets are sequential
     */
    bool isSequential() const override;

    /**
     * This call is not supported on sockets. Reimplemented from QIODevice.
     * This will always return 0.
     */
    qint64 size() const override;

    /**
     * This call is not supported on sockets. Reimplemented from QIODevice.
     * This will always return 0.
     */
    qint64 pos() const override;

    /**
     * This call is not supported on sockets. Reimplemented from QIODevice.
     * This will always return false.
     */
    bool seek(qint64) override;

    /**
     * This call is not supported on sockets. Reimplemented from QIODevice.
     * This will always return true.
     */
    bool atEnd() const override;

    /**
     * Reads data from the socket.
     *
     * Reimplemented from QIODevice. See QIODevice::read for
     * more information.
     */
    qint64 read(char *data, qint64 maxlen);

    /**
     * Reads data from the socket.
     *
     * Reimplemented from QIODevice. See QIODevice::read for
     * more information.
     */
    QByteArray read(qint64 len);

    /** @overload
     * Receives data and the source address.
     *
     * This call will read data in the socket and will also
     * place the sender's address in @p from object.
     *
     * @param data        where to write the read data to
     * @param maxlen      the maximum number of bytes to read
     * @param from        the address of the sender will be stored here
     * @returns the actual number of bytes read
     */
    qint64 read(char *data, qint64 maxlen, KSocketAddress &from);

    /**
     * Peeks the data in the socket and the source address.
     *
     * This call will allow you to peek the data to be received without actually
     * receiving it -- that is, it will be available for further peekings and
     * for the next read call.
     *
     * @param data        where to write the peeked data to
     * @param maxlen      the maximum number of bytes to peek
     * @returns the actual number of bytes copied into @p data
     */
    qint64 peek(char *data, qint64 maxlen);

    /**
     * @overload
     * Peeks the data in the socket and the source address.
     *
     * This call will allow you to peek the data to be received without actually
     * receiving it -- that is, it will be available for further peekings and
     * for the next read call.
     *
     * @param data        where to write the peeked data to
     * @param maxlen      the maximum number of bytes to peek
     * @param from        the address of the sender will be stored here
     * @returns the actual number of bytes copied into @p data
     */
    qint64 peek(char *data, qint64 maxlen, KSocketAddress &from);

    /**
     * Writes the given data to the socket.
     *
     * Reimplemented from QIODevice. See QIODevice::write for
     * more information.
     */
    qint64 write(const char *data, qint64 len);

    /**
     * Writes the given data to the socket.
     *
     * Reimplemented from QIODevice. See QIODevice::write for
     * more information.
     */
    qint64 write(const QByteArray &data);

    /** @overload
     * Writes the given data to the destination address.
     *
     * Note that not all socket connections allow sending data to different
     * addresses than the one the socket is connected to.
     *
     * @param data        the data to write
     * @param len         the length of the data
     * @param to          the address to send to
     * @returns the number of bytes actually sent
     */
    qint64 write(const char *data, qint64 len, const KSocketAddress &to);

    /**
     * Waits up to @p msecs for more data to be available on this socket.
     *
     * If msecs is -1, this call will block indefinetely until more data
     * is indeed available; if it's 0, this function returns immediately.
     *
     * If @p timeout is not NULL, this function will set it to indicate
     * if a timeout occurred.
     *
     * @returns the number of bytes available
     */
    virtual qint64 waitForMore(int msecs, bool *timeout = nullptr) = 0;

    /**
     * This call is not supported on sockets. Reimplemented from QIODevice.
     */
    void ungetChar(char);

    /**
     * Returns this socket's local address.
     */
    virtual KSocketAddress localAddress() const = 0;

    /**
     * Return this socket's peer address, if we are connected.
     * If the address cannot be retrieved, the returned object will contain
     * an invalid address.
     */
    virtual KSocketAddress peerAddress() const = 0;

    // FIXME KDE 4.0:
    // enable this function
#if 0
    /**
     * Returns this socket's externally-visible address, if known.
     */
    virtual KSocketAddress externalAddress() const = 0;
#endif

protected:
    /**
     * Reads data from the socket.
     *
     * Reimplemented from QIODevice. See QIODevice::readData for
     * more information.
     */
    qint64 readData(char *data, qint64 len) override;

    /** @overload
     * Receives data and the source address.
     *
     * This call will read data in the socket and will also
     * place the sender's address in @p from object.
     *
     * @param data        where to write the read data to
     * @param maxlen      the maximum number of bytes to read
     * @param from        the address of the sender will be stored here
     * @returns the actual number of bytes read
     */
    virtual qint64 readData(char *data, qint64 maxlen, KSocketAddress *from) = 0;

    /**
     * Peeks the data in the socket and the source address.
     *
     * This call will allow you to peek the data to be received without actually
     * receiving it -- that is, it will be available for further peekings and
     * for the next read call.
     *
     * @param data        where to write the peeked data to
     * @param maxlen      the maximum number of bytes to peek
     * @param from        the address of the sender will be stored here
     * @returns the actual number of bytes copied into @p data
     */
    virtual qint64 peekData(char *data, qint64 maxlen, KSocketAddress *from) = 0;

    /**
     * Writes the given data to the socket.
     *
     * Reimplemented from QIODevice. See QIODevice::writeData for
     * more information.
     */
    qint64 writeData(const char *data, qint64 len) override;

    /** @overload
     * Writes the given data to the destination address.
     *
     * Note that not all socket connections allow sending data to different
     * addresses than the one the socket is connected to.
     *
     * @param data        the data to write
     * @param len         the length of the data
     * @param to          the address to send to
     * @returns the number of bytes actually sent
     */
    virtual qint64 writeData(const char *data, qint64 len, const KSocketAddress *to) = 0;

    /**
     * Sets the socket's error code.
     *
     * @param error       the error code
     */
    void setError(SocketError error);

    /**
     * Resets the socket error code and the I/O Device's status.
     */
    void resetError();
};

/**
 * @class KPassiveSocketBase k3socketbase.h k3socketbase.h
 * @brief Abstract base class for passive sockets.
 *
 * This socket provides the initial functionality for passive sockets,
 * i.e., sockets that accept incoming connections.
 *
 * @author Thiago Macieira <thiago@kde.org>
 * @deprecated Use KSocketFactory or KLocalSocket instead
 */
class KDELIBS4SUPPORT_DEPRECATED_EXPORT KPassiveSocketBase: virtual public KSocketBase
{
public:
    /**
     * Constructor
     */
    KPassiveSocketBase();

    /**
     * Destructor
     */
    virtual ~KPassiveSocketBase();

    /**
     * Binds this socket to the given address.
     *
     * The socket will be constructed with the address family,
     * socket type and protocol as those given in the
     * @p address object.
     *
     * @param address     the address to bind to
     * @returns true if the binding was successful, false otherwise
     */
    virtual bool bind(const KResolverEntry &address) = 0;

    /**
     * Puts this socket into listening mode.
     *
     * Placing a socket in listening mode means that it will
     * be allowed to receive incoming connections from
     * remote hosts.
     *
     * Note that some socket types or protocols cannot be
     * put in listening mode.
     *
     * @param backlog     the number of accepted connections to
     *                hold before starting to refuse
     * @returns true if the socket is now in listening mode
     */
    virtual bool listen(int backlog) = 0;

    /**
     * Closes this socket. All resources used are freed. Note that closing
     * a passive socket does not close the connections accepted with it.
     */
    virtual void close() = 0;

    /**
     * Accepts a new incoming connection.
     *
     * If this socket was in listening mode, you can call this
     * function to accept an incoming connection.
     *
     * If this function cannot accept a new connection (either
     * because it is not listening for one or because the operation
     * would block), it will return NULL.
     *
     * Also note that descended classes will override this function
     * to return specialized socket classes.
     */
    virtual KActiveSocketBase *accept() = 0;

    /**
     * Returns this socket's local address.
     */
    virtual KSocketAddress localAddress() const = 0;

    /**
     * Returns this socket's externally-visible address if known.
     */
    virtual KSocketAddress externalAddress() const = 0;

private:
    KPassiveSocketBase(const KPassiveSocketBase &);
    KPassiveSocketBase &operator = (const KPassiveSocketBase &);
};

}               // namespace KNetwork

#endif
