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group-ipc.h

/*
 * Copyright (c) 1991-1994 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and the Network Research Group at
 *      Lawrence Berkeley Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * @(#) $Header: group-ipc.h,v 1.7 95/10/07 18:14:53 mccanne Exp $ (LBL)
 */

#ifndef vat_group_ipc_h
#define vat_group_ipc_h

#include "config.h"
#include "inet.h"
#include "iohandler.h"

#define GIPC_MTU 512
#define GIPC_MAGIC 0x0ef5ee0a

#define           GIPC_AA_WANT            1
#define           GIPC_AA_RELEASE         2
#define           GIPC_RANK         3
#define           GIPC_TALK         4

struct ipchdr {
      u_int32_t magic;  /* detect bogus traffic from inpcb bug */
      u_short type;
      u_short pid;
};

class IPCHandler {
 protected:
      IPCHandler(int typemask);
 public:
      virtual void ipc_input(int type, int frompid,
                         u_char* msg, int len) = 0;
      IPCHandler* next_;
      inline int mask() const { return (mask_); }
 private:
      int mask_;
};

/*
 * A class for group ipc.  We use a IP multicast socket with ttl 0
 * to effect multi-process communication.  A single, reserved multicast
 * address and unique port numbers gives us a set of communication
 * "channels" (the port number is GROUP_IPC_PORT + channel).
 * The convention is that channel 0 is used globally, among all
 * conference applications, while other channels are private to
 * individual conferences.  Channels numbers only need to be unique
 * at the local host, and can be easily specified with a conference
 * control tool (e.g., sd).
 */
class GroupIPC : public IOHandler {
    public:
      GroupIPC(int channel);
      ~GroupIPC();
      void attach(IPCHandler*);
      void send(int type, int len);
      void send(int type, const char* msg);
      inline u_char* buffer() { return ((u_char*)buffer_ + sizeof(ipchdr)); }
    protected:
      virtual void dispatch(int);
    private:
      IPCHandler* handlers_;
      int rsock_;
      int ssock_;
      int pid_;
      u_long buffer_[GIPC_MTU / sizeof(u_long)];
};

#endif

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