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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 *    must display the following acknowledgement:
 *      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 1.18 2001/09/04 23:34:55 kfall 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) */
        /*
         * 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) */

        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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