/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2006 Georgia Tech Research Corporation

 *               2007 INRIA

 *

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

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * This program 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 for more details.

 *

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

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * Authors: George F. Riley<riley@ece.gatech.edu>

 *          Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 */

#ifndef __SOCKET_H__

#define __SOCKET_H__

#include "ns3/callback.h"

#include "ns3/ptr.h"

#include "ns3/tag.h"

#include "ns3/object.h"

#include "address.h"

#include <stdint.h>

namespace ns3 {

class Node;

class Packet;

/**

 * \ingroup node

 * \defgroup socket Socket

 */

/**

 * \brief A low-level Socket API based loosely on the BSD Socket API.

 * \ingroup socket

 *

 * A few things to keep in mind about this type of socket:

 * - it uses ns-3 API constructs such as class ns3::Address instead of

 *   C-style structs

 * - in contrast to the original BSD socket API, this API is asynchronous:

 *   it does not contain blocking calls.  Sending and receiving operations

 *   must make use of the callbacks provided. 

 * - It also uses class ns3::Packet as a fancy byte buffer, allowing 

 *   data to be passed across the API using an ns-3 Packet instead of 

 *   a raw data pointer.  

 * - Not all of the full POSIX sockets API is supported

 *

 * Other than that, it tries to stick to the BSD API to make it 

 * easier for those who know the BSD API to use this API.  

 * More details are provided in the ns-3 tutorial.

 */

class Socket : public Object

{

public:

  Socket (void);

  virtual ~Socket (void);

  enum SocketErrno {

    ERROR_NOTERROR,

    ERROR_ISCONN,

    ERROR_NOTCONN,

    ERROR_MSGSIZE,

    ERROR_AGAIN,

    ERROR_SHUTDOWN,

    ERROR_OPNOTSUPP,

    ERROR_AFNOSUPPORT,

    ERROR_INVAL,

    ERROR_BADF,

    ERROR_NOROUTETOHOST,

    SOCKET_ERRNO_LAST

  };

  /**

   * This method wraps the creation of sockets that is performed

   * by a socket factory on a given node based on a TypeId.

   * 

   * \return A smart pointer to a newly created socket.

   * 

   * \param node The node on which to create the socket

   * \param tid The TypeId of the socket to create

   */

  static Ptr<Socket> CreateSocket (Ptr<Node> node, TypeId tid);

  /**

   * \return the errno associated to the last call which failed in this

   *         socket. Each socket's errno is initialized to zero

   *         when the socket is created.

   */

  virtual enum Socket::SocketErrno GetErrno (void) const = 0;

  /**

   * \returns the node this socket is associated with.

   */

  virtual Ptr<Node> GetNode (void) const = 0;

  /**

   * \param connectionSucceeded this callback is invoked when the 

   *        connection request initiated by the user is successfully 

   *        completed. The callback is passed  back a pointer to 

   *        the same socket object.

   * \param connectionFailed this callback is invoked when the 

   *        connection request initiated by the user is unsuccessfully 

   *        completed. The callback is passed back a pointer to the 

   *        same socket object. 

   */

  void SetConnectCallback (Callback<void, Ptr<Socket> > connectionSucceeded,

                           Callback<void,  Ptr<Socket> > connectionFailed);

  /**

   * \brief Accept connection requests from remote hosts

   * \param connectionRequest Callback for connection request from peer. 

   *        This user callback is passed a pointer to this socket, the 

   *        ip address and the port number of the connection originator. 

   *        This callback must return true to accept the incoming connection,

   *        false otherwise. If the connection is accepted, the 

   *        "newConnectionCreated" callback will be invoked later to 

   *        give access to the user to the socket created to match 

   *        this new connection. If the user does not explicitly 

   *        specify this callback, all incoming  connections will be refused.

   * \param newConnectionCreated Callback for new connection: when a new

   *        is accepted, it is created and the corresponding socket is passed

   *        back to the user through this callback. This user callback is 

   *        passed a pointer to the new socket, and the ip address and 

   *        port number of the connection originator.

   */

  void SetAcceptCallback (Callback<bool, Ptr<Socket>, 

                            const Address &> connectionRequest,

                          Callback<void, Ptr<Socket>, 

                            const Address&> newConnectionCreated);

  /**

   * \brief Notify application when a packet has been sent from transport 

   *        protocol (non-standard socket call)

   * \param dataSent Callback for the event that data is sent from the

   *        underlying transport protocol.  This callback is passed a

   *        pointer to the socket, and the number of bytes sent.

   * \returns whether or not this socket supports this callback.  Note 

   *        that this is a non-standard socket call.  Some socket 

   *        implementations in ns-3 may not support this call, so the

   *        user should check this return value to confirm that the

   *        callback is supported.

   */

  bool SetDataSentCallback (Callback<void, Ptr<Socket>, 

                            uint32_t> dataSent);

  /**

   * \brief Notify application when space in transmit buffer is added

   *

   *        This callback is intended to notify a 

   *        socket that would have been blocked in a blocking socket model

   *        that space is available in the transmit buffer and that it

   *        can call Send() again.  

   *

   * \param sendCb Callback for the event that the socket transmit buffer

   *        fill level has decreased.  This callback is passed a pointer to

   *        the socket, and the number of bytes available for writing

   *        into the buffer (an absolute value).  If there is no transmit

   *        buffer limit, a maximum-sized integer is always returned.

   */

  void SetSendCallback (Callback<void, Ptr<Socket>, uint32_t> sendCb);

  /**

   * \brief Notify application when new data is available to be read.

   *

   *        This callback is intended to notify a socket that would

   *        have been blocked in a blocking socket model that data

   *        is available to be read.

   */

  void SetRecvCallback (Callback<void, Ptr<Socket> >);

  /** 

   * \param address the address to try to allocate

   * \returns 0 on success, -1 on failure.

   *

   * Allocate a local endpoint for this socket.

   */

  virtual int Bind (const Address &address) = 0;

  /** 

   * Allocate a local endpoint for this socket.

   *

   * \returns 0 on success, -1 on failure.

   */

  virtual int Bind () = 0;

  /** 

   * \brief Close a socket.

   *

   * After the Close call, the socket is no longer valid, and cannot

   * safely be used for subsequent operations.

   */

  virtual int Close (void) = 0;

  /**

   * \returns zero on success, -1 on failure.

   *

   * Do not allow any further Send calls. This method is typically

   * implemented for Tcp sockets by a half close.

   */

  virtual int ShutdownSend (void) = 0;

  /**

   * \returns zero on success, -1 on failure.

   *

   * Do not allow any further Recv calls. This method is typically

   * implemented for Tcp sockets by a half close.

   */

  virtual int ShutdownRecv (void) = 0;

  /**

   * \brief Initiate a connection to a remote host

   * \param address Address of remote.

   */

  virtual int Connect (const Address &address) = 0;

  /**

   * \brief Listen for incoming connections.

   * \param queueLimit maximum number of incoming request to queue

   * \returns 0 on success, -1 on error (in which case errno is set).

   */

  virtual int Listen (uint32_t queueLimit) = 0;

  /**

   * \brief Returns the number of bytes which can be sent in a single call

   * to Send. 

   * 

   * For datagram sockets, this returns the number of bytes that

   * can be passed atomically through the underlying protocol.

   *

   * For stream sockets, this returns the available space in bytes

   * left in the transmit buffer.

   */

  virtual uint32_t GetTxAvailable (void) const = 0;

  /**

   * \brief Send data (or dummy data) to the remote host

   *

   * This function matches closely in semantics to the send() function

   * call in the standard C library (libc):

   *   ssize_t send (int s, const void *msg, size_t len, int flags);

   * except that the send I/O is asynchronous.  This is the

   * primary Send method at this low-level API and must be implemented 

   * by subclasses.

   * 

   * In a typical blocking sockets model, this call would block upon

   * lack of space to hold the message to be sent.  In ns-3 at this

   * API, the call returns immediately in such a case, but the callback

   * registered with SetSendCallback() is invoked when the socket

   * has space (when it conceptually unblocks); this is an asynchronous

   * I/O model for send().

   * 

   * This variant of Send() uses class ns3::Packet to encapsulate

   * data, rather than providing a raw pointer and length field.  

   * This allows an ns-3 application to attach tags if desired (such

   * as a flow ID) and may allow the simulator to avoid some data

   * copies.  Despite the appearance of sending Packets on a stream

   * socket, just think of it as a fancy byte buffer with streaming

   * semantics.    

   *

   * If either the message buffer within the Packet is too long to pass 

   * atomically through the underlying protocol (for datagram sockets), 

   * or the message buffer cannot entirely fit in the transmit buffer

   * (for stream sockets), -1 is returned and SocketErrno is set 

   * to ERROR_MSGSIZE.  If the packet does not fit, the caller can

   * split the Packet (based on information obtained from 

   * GetTxAvailable) and reattempt to send the data.

   *

   * The flags argument is formed by or'ing one or more of the values:     

   *        MSG_OOB        process out-of-band data 

   *        MSG_DONTROUTE  bypass routing, use direct interface 

   * These flags are _unsupported_ as of ns-3.1.  

   *

   * \param p ns3::Packet to send

   * \param flags Socket control flags

   * \returns the number of bytes accepted for transmission if no error

   *          occurs, and -1 otherwise.

   *

   * \see SetSendCallback

   */

  virtual int Send (Ptr<Packet> p, uint32_t flags) = 0;

  /**

   * \brief Send data to a specified peer.

   *

   * This method has similar semantics to Send () but subclasses may

   * want to provide checks on socket state, so the implementation is

   * pushed to subclasses.

   *

   * \param p packet to send

   * \param flags Socket control flags

   * \param toAddress IP Address of remote host

   * \returns -1 in case of error or the number of bytes copied in the 

   *          internal buffer and accepted for transmission.

   */

  virtual int SendTo (Ptr<Packet> p, uint32_t flags, 

    const Address &toAddress) = 0;

  /**

   * Return number of bytes which can be returned from one or 

   * multiple calls to Recv.

   * Must be possible to call this method from the Recv callback.

   */

  virtual uint32_t GetRxAvailable (void) const = 0;

  /**

   * \brief Read data from the socket

   *

   * This function matches closely in semantics to the recv() function

   * call in the standard C library (libc):

   *   ssize_t recv (int s, void *buf, size_t len, int flags);

   * except that the receive I/O is asynchronous.  This is the

   * primary Recv method at this low-level API and must be implemented 

   * by subclasses.

   * 

   * This method is normally used only on a connected socket.

   * In a typical blocking sockets model, this call would block until

   * at least one byte is returned or the connection closes.  

   * In ns-3 at this API, the call returns immediately in such a case

   * and returns 0 if nothing is available to be read.

   * However, an application can set a callback, ns3::SetRecvCallback,

   * to be notified of data being available to be read

   * (when it conceptually unblocks); this is an asynchronous

   * I/O model for recv().

   * 

   * This variant of Recv() uses class ns3::Packet to encapsulate

   * data, rather than providing a raw pointer and length field.  

   * This allows an ns-3 application to attach tags if desired (such

   * as a flow ID) and may allow the simulator to avoid some data

   * copies.  Despite the appearance of receiving Packets on a stream

   * socket, just think of it as a fancy byte buffer with streaming

   * semantics.    

   *

   * The semantics depend on the type of socket.  For a datagram socket,

   * each Recv() returns the data from at most one Send(), and order

   * is not necessarily preserved.  For a stream socket, the bytes

   * are delivered in order, and on-the-wire packet boundaries are

   * not preserved.  

   * 

   * The flags argument is formed by or'ing one or more of the values:     

   *        MSG_OOB        process out-of-band data

   *        MSG_PEEK       peek at incoming message

   * These flags are _unsupported_ as of ns-3.1.  

   *

   * Some variants of Recv() are supported as additional API,

   * including RecvFrom(), overloaded Recv() without arguments,

   * and variants that use raw character buffers.

   *

   * \param maxSize reader will accept packet up to maxSize

   * \param flags Socket control flags

   * \returns Ptr<Packet> of the next in-sequence packet.  Returns

   * 0 if the socket cannot return a next in-sequence packet conforming

   * to the maxSize and flags.

   *

   * \see SetRecvCallback

   */

  virtual Ptr<Packet> Recv (uint32_t maxSize, uint32_t flags) = 0;

  /**

   * \brief Read a single packet from the socket and retrieve the sender 

   * address.

   *

   * Calls Recv(maxSize, flags) with maxSize

   * implicitly set to maximum sized integer, and flags set to zero.

   *

   * This method has similar semantics to Recv () but subclasses may   

   * want to provide checks on socket state, so the implementation is   

   * pushed to subclasses.

   *

   * \param maxSize reader will accept packet up to maxSize

   * \param flags Socket control flags

   * \param fromAddress output parameter that will return the

   * address of the sender of the received packet, if any.  Remains

   * untouched if no packet is received.

   * \returns Ptr<Packet> of the next in-sequence packet.  Returns

   * 0 if the socket cannot return a next in-sequence packet.

   */

  virtual Ptr<Packet> RecvFrom (uint32_t maxSize, uint32_t flags,  

    Address &fromAddress) = 0;

  /////////////////////////////////////////////////////////////////////

  //   The remainder of these public methods are overloaded methods  //

  //   or variants of Send() and Recv(), and they are non-virtual    //

  /////////////////////////////////////////////////////////////////////

  /**

   * \brief Send data (or dummy data) to the remote host

   * 

   * Overloaded version of Send(..., flags) with flags set to zero.

   *

   * \param p ns3::Packet to send

   * \returns the number of bytes accepted for transmission if no error

   *          occurs, and -1 otherwise.

   */

  int Send (Ptr<Packet> p);

  /**

   * \brief Send data (or dummy data) to the remote host

   * 

   * This method is provided so as to have an API which is closer in 

   * appearance to that of real network or BSD sockets.  

   *

   * \param buf A pointer to a raw byte buffer of some data to send.  If 

   * this buffer is 0, we send dummy data whose size is specified by the 

   * second parameter

   * \param size the number of bytes to copy from the buffer

   * \param flags Socket control flags

   */

  int Send (const uint8_t* buf, uint32_t size, uint32_t flags);

  /**

   * \brief Send data to a specified peer.

   *

   * This method is provided so as to have an API which is closer in 

   * appearance to that of real network or BSD sockets.  

   *

   * \param buf A pointer to a raw byte buffer of some data to send.  

   * If this is 0, we send dummy data whose size is specified by the 

   * third parameter

   * \param size the number of bytes to copy from the buffer

   * \param flags Socket control flags

   * \param address IP Address of remote host

   * \returns -1 in case of error or the number of bytes copied in the 

   *          internal buffer and accepted for transmission.

   *

   */

  int SendTo (const uint8_t* buf, uint32_t size, uint32_t flags, 

              const Address &address); 

  /**

   * \brief Read a single packet from the socket

   *

   * Overloaded version of Recv(maxSize, flags) with maxSize

   * implicitly set to maximum sized integer, and flags set to zero.

   *

   * \returns Ptr<Packet> of the next in-sequence packet.  Returns

   * 0 if the socket cannot return a next in-sequence packet.

   */

   Ptr<Packet> Recv (void);

  /**

   * \brief Recv data (or dummy data) from the remote host

   *

   * This method is provided so as to have an API which is closer in 

   * appearance to that of real network or BSD sockets.  

   * 

   * If the underlying packet was carring null (fake) data, this buffer

   * will be zeroed up to the length specified by the return value.

   *

   * \param buf A pointer to a raw byte buffer to write the data to. 

   * \param size Number of bytes (at most) to copy to buf

   * \param flags any flags to pass to the socket

   * \returns number of bytes copied into buf

   */

  int Recv (uint8_t* buf, uint32_t size, uint32_t flags);

  /**

   * \brief Read a single packet from the socket and retrieve the sender 

   * address.

   *

   * Calls RecvFrom (maxSize, flags, fromAddress) with maxSize

   * implicitly set to maximum sized integer, and flags set to zero.

   *

   * \param fromAddress output parameter that will return the

   * address of the sender of the received packet, if any.  Remains

   * untouched if no packet is received.

   * \returns Ptr<Packet> of the next in-sequence packet.  Returns

   * 0 if the socket cannot return a next in-sequence packet.

   */

  Ptr<Packet> RecvFrom (Address &fromAddress);

  /**

   * \brief Read a single packet from the socket and retrieve the sender

   * address.

   *

   * This method is provided so as to have an API which is closer in 

   * appearance to that of real network or BSD sockets.  

   * 

   * \param buf A pointer to a raw byte buffer to write the data to. 

   * If the underlying packet was carring null (fake) data, this buffer

   * will be zeroed up to the length specified by the return value.

   * \param size Number of bytes (at most) to copy to buf

   * \param flags any flags to pass to the socket

   * \param fromAddress output parameter that will return the

   * address of the sender of the received packet, if any.  Remains

   * untouched if no packet is received.