raw_socket.h

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#ifndef RAW_SOCKET_CLASS
#define RAW_SOCKET_CLASS

/*****************************************************************************\
*                                                                             *
*  Name   : raw_socket                                                        *
*  Author : Chris Koeritz                                                     *
*                                                                             *
*  Purpose:                                                                   *
*                                                                             *
*    Provides access to the operating system's socket methods.                *
*                                                                             *
*******************************************************************************
* Copyright (c) 1991-$now By Author.  This program is free software; you can  *
* redistribute it and/or modify it under the terms of the GNU General Public  *
* License as published by the Free Software Foundation; either version 2 of   *
* the License or (at your option) any later version.  This is online at:      *
*     http://www.fsf.org/copyleft/gpl.html                                    *
* Please send any updates to: fred@gruntose.com                               *
\*****************************************************************************/

// NOTE: This class does not provide any sort of synchronization of the
// sockets involved.  If you have multiple threads arbitrarily calling select
// and read, then some selects will claim the socket was disconnected (since
// the other thread might have grabbed the data that seemed to be ready but
// then wasn't--a sign of a disconnect).  Ensure that your accesses of the
// socket are serialized.

#include "sockets_dll.h"

#include <basis/object_base.h>

// forward.
class fd_set_wrapper;
class tcpip_stack;

class SOCKETS_CLASS_STYLE raw_socket : public virtual object_base
{
public:
  raw_socket();

  ~raw_socket();

  IMPLEMENT_CLASS_NAME("raw_socket");

//  int open(
//hmmm...

  int close(u_int &socket);
    // disconnects, destroys and resets the "socket" to zero.

  int ioctl(u_int socket, int request, void *argp) const;
    // manipulates the device parameters for the "socket".

  bool set_non_blocking(u_int socket, bool non_blocking = true);
    // makes the "socket" into a non-blocking socket if "non_blocking" is true.
    // if "non_blocking" is false, then the socket is reset to blocking mode.

  bool set_nagle_algorithm(u_int socket, bool use_nagle = true);
    // sets the nagle algorithm on "socket" if "use_nagle" is true.  note that
    // true is the default when a socket is created; to change that for the
    // socket, "use_nagle" should be false.

  bool set_broadcast(u_int socket, bool broadcasting = true);
    // sets broadcast mode on the socket so that it can receive packets that
    // are broadcast to the network.

  bool set_reuse_address(u_int socket, bool reuse = true);
    // sets the socket to allow an address to be re-used when it's already
    // in use, rather than getting a bind error.

  bool set_keep_alive(u_int socket, bool keep_alive = true);
    // marks a connected-mode socket so that keep alive packets will be sent
    // occasionally to ensure that a disconnection is noticed.

  static istring interest_name(int to_name);
    // returns the textual form for the interests set in "to_name".

  // outlines any special constraints on the select invocation.
  enum select_types {
    SELECTING_JUST_WRITE = 0x1,
    SELECTING_JUST_READ = 0x2
  };

  int select(u_int socket, int selection_mode, int timeout = 0) const;
    // this is similar to the low-level select on a bsd socket.  usually this
    // will return events of any type--read, write and exception.  exceptions
    // will always be cause for a return, but if you just want to look at a
    // read condition, include the JUST_READ flag in the "selection_mode".  to
    // just check for write, add the JUST_WRITE flag.  this function returns a
    // bitwise ORed value from the different types of 'socket_interests' (see
    // tcpip definitions, which is where the enum is currently stored).  if
    // there are no special conditions noted on the socket, then zero is
    // returned.  if the "timeout" is zero, the function will return right
    // away.  if "timeout" (measured in milliseconds) is non-zero, then the
    // function will wait until the condition becomes true or the "timeout"
    // elapses.  note: no infinite timeouts are provided here.

  int select(int_array &read_sox, int_array &write_sox, int timeout = 0) const;
    // similar to select above, but operates on a list of sockets in the
    // "read_sox" and "write_sox".  the "read_sox" are checked to see whether
    // those sockets have data pending that could be read.  the "write_sox" are
    // checked to see if the sockets are currently writable without blocking.
    // if any sockets have events applicable to the "selection_mode", then they
    // will still be present in the lists when the call returns.  zero is
    // returned if absolutely nothing happened during the "timeout" period;
    // otherwise, a non-zero number is returned but the individual sockets
    // must still be inspected to determine what happened.

  int analyze_select_result(u_int socket, int mode, fd_set_wrapper &read_list,
          fd_set_wrapper &write_list, fd_set_wrapper &exceptions) const;
    // examines the "socket" in the fd_sets passed in and returns a result
    // based on those sets and the "mode".

private:
  tcpip_stack *_stack;

  int test_readability(u_int socket) const;
    // checks on the readability state for the "socket", assuming that select()
    // reported the socket as readable, and returns either SI_ERRONEOUS,
    // SI_READABLE or SI_DISCONNECTED based on what ioctl() says about it.

  int inner_select(u_int socket, int selection_mode, int timeout,
          fd_set_wrapper &read_list, fd_set_wrapper &write_list,
          fd_set_wrapper &exceptions) const;
    // intermediate function that doesn't attempt to fully analyze the select
    // result.  the returned value will be non-zero if something interesting
    // is happening on the socket.  if that value is SI_ERRONEOUS, then
    // something bad happened to the socket.  the other non-zero value is
    // SI_BASELINE, which means the socket has something to report in the
    // fd_set parameters.
};

#endif

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