flags.h

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/* -*-  Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
/*
 * Copyright (c) 1997 Regents of the University of California.
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 *  This product includes software developed by the MASH Research
 *  Group at the University of California Berkeley.
 * 4. Neither the name of the University nor of the Research Group may be
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 * @(#) $Header: /nfs/jade/vint/CVSROOT/ns-2/common/flags.h,v 1.19 2004/10/28 01:20:10 sfloyd Exp $
 */

/*
 * contains a "flags header", which is common to each packet
 */

#ifndef ns_flags_h
#define ns_flags_h

#include "config.h"
#include "packet.h"

struct hdr_flags {
    unsigned char ecn_;      /* transport receiver notifying
                      *  transport sender of ECN 
                      *  (ECN Echo bit in TCP header) */
    unsigned char ecn_to_echo_;  /* ecn to be echoed back in the *
                      * opposite direction *
                      * (CE bit in IP header) */
    unsigned char eln_;     /* explicit loss notification (snoop) */
    unsigned char fs_;  /* tcp fast start (work in progress --venkat) */
    unsigned char no_ts_;   /* don't use the tstamp of this pkt for rtt */
    unsigned char pri_; /* unused */
    unsigned char ecn_capable_;  /* an ecn-capable tranport *
                      * (ECT bit in IP header) */
    unsigned char cong_action_;  /* Congestion Action.  Transport 
                      * sender notifying transport
                      * receiver of responses to congestion.
                      * (CWR bit in TCP header) */
    unsigned char qs_;  /* Packet is from Quick-Start window, i.e.
                 * a window following an approved QS request.
                 */
    /*
     * these functions use the newer ECN names but leaves the actual field
     * names above to maintain backward compat
     */
    unsigned char& ect()    { return ecn_capable_; }
                      /* (ECT bit in IP header) */
    unsigned char& ecnecho() { return ecn_; }
                      /* (ECN Echo bit in TCP header) */
    unsigned char& ce() { return ecn_to_echo_; }
                      /* (CE bit in IP header) */
    unsigned char& cong_action() { return cong_action_; }
                      /* (CWR bit in TCP header-old name) */
    unsigned char& cwr() { return cong_action_; }
                      /* (CWR bit in TCP header) */

    unsigned char& qs() { return qs_; } /* Quick-Start packet */

    static int offset_;
    inline static int& offset() { return offset_; }
    inline static hdr_flags* access(const Packet* p) {
        return (hdr_flags*) p->access(offset_);
    }
};

#endif

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