tcp.h

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/* -*-  Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
/*
 * Copyright (c) 1991-1997 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 Computer Systems
 *      Engineering 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: /nfs/jade/vint/CVSROOT/ns-2/tcp/tcp.h,v 1.107 2003/02/12 04:16:10 sfloyd Exp $ (LBL)
 */
#ifndef ns_tcp_h
#define ns_tcp_h

#include "agent.h"
#include "packet.h"

//class EventTrace;

struct hdr_tcp {
#define NSA 3
        double ts_;             /* time packet generated (at source) */
        double ts_echo_;        /* the echoed timestamp (originally sent by
                                   the peer) */
        int seqno_;             /* sequence number */
        int reason_;            /* reason for a retransmit */
        int sack_area_[NSA+1][2];       /* sack blocks: start, end of block */
        int sa_length_;         /* Indicate the number of SACKs in this  *
                                 * packet.  Adds 2+sack_length*8 bytes   */ 
        int ackno_;             /* ACK number for FullTcp */
        int hlen_;              /* header len (bytes) for FullTcp */
        int tcp_flags_;         /* TCP flags for FullTcp */
        int last_rtt_;          /* more recent RTT measurement in ms, */
                                /*   for statistics only */

        static int offset_;     // offset for this header
        inline static int& offset() { return offset_; }
        inline static hdr_tcp* access(Packet* p) {
                return (hdr_tcp*) p->access(offset_);
        }

        /* per-field member functions */
        double& ts() { return (ts_); }
        double& ts_echo() { return (ts_echo_); }
        int& seqno() { return (seqno_); }
        int& reason() { return (reason_); }
        int& sa_left(int n) { return (sack_area_[n][0]); }
        int& sa_right(int n) { return (sack_area_[n][1]); }
        int& sa_length() { return (sa_length_); }
        int& hlen() { return (hlen_); }
        int& ackno() { return (ackno_); }  
        int& flags() { return (tcp_flags_); }
        int& last_rtt() { return (last_rtt_); }
};

/* these are used to mark packets as to why we xmitted them */
#define TCP_REASON_TIMEOUT      0x01
#define TCP_REASON_DUPACK       0x02
#define TCP_REASON_RBP          0x03   // used only in tcp-rbp.cc
#define TCP_REASON_PARTIALACK   0x04

/* these are reasons we adjusted our congestion window */

#define CWND_ACTION_DUPACK      1       // dup acks/fast retransmit
#define CWND_ACTION_TIMEOUT     2       // retransmission timeout
#define CWND_ACTION_ECN         3       // ECN bit [src quench if supported]

/* these are bits for how to change the cwnd and ssthresh values */

#define CLOSE_SSTHRESH_HALF     0x00000001
#define CLOSE_CWND_HALF         0x00000002
#define CLOSE_CWND_RESTART      0x00000004
#define CLOSE_CWND_INIT         0x00000008
#define CLOSE_CWND_ONE          0x00000010
#define CLOSE_SSTHRESH_HALVE    0x00000020
#define CLOSE_CWND_HALVE        0x00000040
#define THREE_QUARTER_SSTHRESH  0x00000080
#define CLOSE_CWND_HALF_WAY     0x00000100
#define CWND_HALF_WITH_MIN      0x00000200

/*
 * tcp_tick_:
 * default 0.1,
 * 0.3 for 4.3 BSD, 
 * 0.01 for new window algorithms,
 */

#define NUMDUPACKS 3            /* This is no longer used.  The variable */
                                /* numdupacks_ is used instead. */
#define TCP_MAXSEQ 1073741824   /* Number that curseq_ is set to for */
                                /* "infinite send" (2^30)            */

#define TCP_TIMER_RTX           0
#define TCP_TIMER_DELSND        1
#define TCP_TIMER_BURSTSND      2
#define TCP_TIMER_DELACK        3
#define TCP_TIMER_Q         4
#define TCP_TIMER_RESET        5 

class TcpAgent;

class RtxTimer : public TimerHandler {
public: 
        RtxTimer(TcpAgent *a) : TimerHandler() { a_ = a; }
protected:
        virtual void expire(Event *e);
        TcpAgent *a_;
};

class DelSndTimer : public TimerHandler {
public: 
        DelSndTimer(TcpAgent *a) : TimerHandler() { a_ = a; }
protected:
        virtual void expire(Event *e);
        TcpAgent *a_;
};

class BurstSndTimer : public TimerHandler {
public: 
        BurstSndTimer(TcpAgent *a) : TimerHandler() { a_ = a; }
protected:
        virtual void expire(Event *e);
        TcpAgent *a_;
};


class TcpAgent : public Agent {
public:
        TcpAgent();
        virtual void recv(Packet*, Handler*);
        virtual void timeout(int tno);
        virtual void timeout_nonrtx(int tno);
        int command(int argc, const char*const* argv);
        virtual void sendmsg(int nbytes, const char *flags = 0);

        void trace(TracedVar* v);
        virtual void advanceby(int delta);
protected:
        virtual int window();
        virtual double windowd();
        void print_if_needed(double memb_time);
        void traceAll();
        virtual void traceVar(TracedVar* v);
        virtual int headersize();   // a tcp header

        virtual void delay_bind_init_all();
        virtual int delay_bind_dispatch(const char *varName, const char *localName, TclObject *tracer);

        /*
         * State encompassing the round-trip-time estimate.
         * srtt and rttvar are stored as fixed point;
         * srtt has 3 bits to the right of the binary point, rttvar has 2.
         */
        TracedInt t_seqno_;     /* sequence number */
#define T_RTT_BITS 0
        TracedInt t_rtt_;       /* round trip time */
        int T_SRTT_BITS;        /* exponent of weight for updating t_srtt_ */
        TracedInt t_srtt_;      /* smoothed round-trip time */
        int srtt_init_;         /* initial value for computing t_srtt_ */
        int T_RTTVAR_BITS;      /* exponent of weight for updating t_rttvar_ */ 
        int rttvar_exp_;        /* exponent of multiple for t_rtxcur_ */
        TracedInt t_rttvar_;    /* variance in round-trip time */
        int rttvar_init_;       /* initial value for computing t_rttvar_ */
        double t_rtxcur_;       /* current retransmit value */
        double rtxcur_init_;    /* initial value for t_rtxcur_ */
        TracedInt t_backoff_;   /* current multiplier, 1 if not backed off */
        virtual void rtt_init();
        virtual double rtt_timeout();   /* provide RTO based on RTT estimates */
        virtual void rtt_update(double tao);    /* update RTT estimate */
        virtual void rtt_backoff();             /* double multiplier */

        double ts_peer_;        /* the most recent timestamp the peer sent */

        /* connection and packet dynamics */
        virtual void output(int seqno, int reason = 0);
        virtual void send_much(int force, int reason, int maxburst = 0);
        virtual void newtimer(Packet*);
        virtual void dupack_action();           /* do this on dupacks */
        virtual void send_one();                /* do this on 1-2 dupacks */
        double linear(double x, double x_1, double y_1, double x_2, double y_2);
        /* the "linear" function is for experimental highspeed TCP */
        void opencwnd();

        void slowdown(int how);                 /* reduce cwnd/ssthresh */
        void ecn(int seqno);            /* react to quench */
        virtual void set_initial_window();      /* set IW */
        double initial_window();                /* what is IW? */
        void reset();
        void newack(Packet*);
        void tcp_eln(Packet *pkt); /* reaction to ELN (usually wireless) */
        void finish(); /* called when the connection is terminated */
        void reset_qoption();   /* for QOption with EnblRTTCtr_ */
        void rtt_counting();    /* for QOption with EnblRTTCtr_ */
        int network_limited();  /* Sending limited by network? */
        double limited_slow_start(double cwnd, double max_ssthresh, double increment);
                                /* Limited slow-start for high windows */
        virtual int numdupacks(double cwnd);    /* for getting numdupacks_ */
        virtual void processQuickStart(Packet *pkt);
        virtual void endQuickStart();

        /* Helper functions. Currently used by tcp-asym */
        virtual void output_helper(Packet*) { return; }
        virtual void send_helper(int) { return; }
        virtual void send_idle_helper() { return; }
        virtual void recv_helper(Packet*) { return; }
        virtual void recv_newack_helper(Packet*);
        virtual void partialnewack_helper(Packet*) {};

        /* Timers */
        RtxTimer rtx_timer_;
        DelSndTimer delsnd_timer_;
        BurstSndTimer burstsnd_timer_;
        virtual void cancel_timers() {
                rtx_timer_.force_cancel();
                burstsnd_timer_.force_cancel();
                delsnd_timer_.force_cancel();
        }
        virtual void cancel_rtx_timer() {
                rtx_timer_.force_cancel();
        }
        virtual void set_rtx_timer();
        void reset_rtx_timer(int mild, int backoff = 1);
        int timerfix_;          /* set to true to update timer *after* */
                                /* update the RTT, instead of before   */
        int rfc2988_;           /* Use updated RFC 2988 timers */
        double boot_time_;      /* where between 'ticks' this sytem came up */
        double overhead_;
        double wnd_;
        double wnd_const_;
        double wnd_th_;         /* window "threshold" */
        double wnd_init_;
        double wnd_restart_;
        double tcp_tick_;       /* clock granularity */
        int wnd_option_;
        int wnd_init_option_;   /* 1 for using wnd_init_ */
                                /* 2 for using large initial windows */
        double decrease_num_;   /* factor for multiplicative decrease */
        double increase_num_;   /* factor for additive increase */
        double k_parameter_;     /* k parameter in binomial controls */
        double l_parameter_;     /* l parameter in binomial controls */
        int precision_reduce_;  /* non-integer reduction of cwnd */
        int syn_;               /* 1 for modeling SYN/ACK exchange */
        int delay_growth_;      /* delay opening cwnd until 1st data recv'd */
        int tcpip_base_hdr_size_;  /* size of base TCP/IP header */
        int ts_option_size_;    // header bytes in a ts option
        int bug_fix_;           /* 1 for multiple-fast-retransmit fix */
        int less_careful_;      /* 1 for Less Careful variant of bug_fix_, */
                                /*  for illustration only  */
        int ts_option_;         /* use RFC1323-like timestamps? */
        int maxburst_;          /* max # packets can send back-2-back */
        int maxcwnd_;           /* max # cwnd can ever be */
        int numdupacks_;        /* dup ACKs before fast retransmit */
        int numdupacksFrac_;    /* for a larger numdupacks_ with large */
                                /* windows */
        double maxrto_;         /* max value of an RTO */
        double minrto_;         /* min value of an RTO */
        int old_ecn_;           /* For backwards compatibility with the 
                                 * old ECN implementation, which never
                                 * reduced the congestion window below
                                 * one packet. */ 
        FILE *plotfile_;
        /*
         * Dynamic state.
         */
        TracedInt dupacks_;     /* number of duplicate acks */
        TracedInt curseq_;      /* highest seqno "produced by app" */
        int last_ack_;          /* largest consecutive ACK, frozen during
                                 *              Fast Recovery */
        TracedInt highest_ack_; /* not frozen during Fast Recovery */
        int recover_;           /* highest pkt sent before dup acks, */
                                /*   timeout, or source quench/ecn */
        int last_cwnd_action_;  /* CWND_ACTION_{TIMEOUT,DUPACK,ECN} */
        TracedDouble cwnd_;     /* current window */
        double base_cwnd_;      /* base window (for experimental purposes) */
        double awnd_;           /* averaged window */
        TracedInt ssthresh_;    /* slow start threshold */
        int count_;             /* used in window increment algorithms */
        double fcnt_;           /* used in window increment algorithms */
        int rtt_active_;        /* 1 if a rtt sample is pending */
        int rtt_seq_;           /* seq # of timed seg if rtt_active_ is 1 */
        double rtt_ts_;         /* time at which rtt_seq_ was sent */
        TracedInt maxseq_;      /* used for Karn algorithm */
                                /* highest seqno sent so far */
        int ecn_;               /* Explicit Congestion Notification */
        int cong_action_;       /* Congestion Action.  True to indicate
                                   that the sender responded to congestion. */
        int ecn_burst_;         /* True when the previous ACK packet
                                 *  carried ECN-Echo. */
        int ecn_backoff_;       /* True when retransmit timer should begin
                                    to be backed off.  */
        int ect_;               /* turn on ect bit now? */
        int eln_;               /* Explicit Loss Notification (wireless) */
        int eln_rxmit_thresh_;  /* Threshold for ELN-triggered rxmissions */
        int eln_last_rxmit_;    /* Last packet rxmitted due to ELN info */
        double firstsent_;      /* When first packet was sent  --Allman */
        double lastreset_;      /* W.N. Last time connection was reset - for */
                                /* detecting pkts from previous incarnations */
        int slow_start_restart_; /* boolean: re-init cwnd after connection 
                                    goes idle.  On by default. */
        int restart_bugfix_;    /* ssthresh is cut down because of
                                   timeouts during a connection's idle period.
                                   Setting this boolean fixes this problem.
                                   For now, it is off by default. */ 
        int closed_;            /* whether this connection has closed */
        TracedInt ndatapack_;   /* number of data packets sent */
        TracedInt ndatabytes_;  /* number of data bytes sent */
        TracedInt nackpack_;    /* number of ack packets received */
        TracedInt nrexmit_;     /* number of retransmit timeouts 
                                   when there was data outstanding */
        TracedInt nrexmitpack_; /* number of retransmited packets */
        TracedInt nrexmitbytes_; /* number of retransmited bytes */
        TracedInt necnresponses_; /* number of times cwnd was reduced
                                   in response to an ecn packet -- sylvia */
        TracedInt ncwndcuts_;   /* number of times cwnd was reduced 
                                   for any reason -- sylvia */
        int trace_all_oneline_; /* TCP tracing vars all in one line or not? */
        int nam_tracevar_;      /* Output nam's variable trace or just plain 
                                   text variable trace? */
        int first_decrease_;    /* First decrease of congestion window.  */
                                /* Used for decrease_num_ != 0.5. */
        TracedInt singledup_;   /* Send on a single dup ack.  */
        int noFastRetrans_;     /* No Fast Retransmit option.  */
        int oldCode_;           /* Use old code. */
        int useHeaders_;        /* boolean: Add TCP/IP header sizes */

        /* for experimental high-speed TCP */
        /* These four parameters define the HighSpeed response function. */
        int low_window_;        /* window for turning on high-speed TCP */
        int high_window_;       /* target window for new response function */
        double high_p_;         /* target drop rate for new response function */
        double high_decrease_;  /* decrease rate at target window */
        /* The next parameter is for Limited Slow-Start. */
        int max_ssthresh_;      /* max value for ssthresh_ */

        /* These three functions are just an easy structuring of the code. */ 
        double increase_param();  /* get increase parameter for current cwnd */
        double decrease_param();  /* get decrease parameter for current cwnd */
        double compute_p();     /* compute p for calculating parameters */
        /* The next three parameters are for CPU overhead, for computing */
        /*   the HighSpeed parameters less frequently.  A better solution */
        /*   might be just to have a look-up array.  */
        double cwnd_last_;      /* last cwnd for computed parameters */
        double increase_last_;  /* increase param for cwnd_last_ */
        double cwnd_frac_;      /* for determining when to recompute params. */
        /* end of section for experimental high-speed TCP */

        /* for Quick-Start, experimental. */
        int rate_request_;      /* Rate request in pps, for QuickStart. */
        int qs_enabled_; /* to enable QuickStart. */
        int qs_requested_;
        int qs_approved_;
        int ttl_diff_;
        /* end of section for Quick-Start. */

        /* support for event-tracing */
        //EventTrace *et_;
        void trace_event(char *eventtype);

        /* these function are now obsolete, see other above */
        void closecwnd(int how);
        void quench(int how);

        void process_qoption_after_send() ;
        void process_qoption_after_ack(int seqno) ;

        int QOption_ ; /* TCP quiescence option */
        int EnblRTTCtr_ ; /* are we using a corase grained timer? */
        int T_full ; /* last time the window was full */
        int T_last ;
        int T_prev ;
        int T_start ;
        int RTT_count ;
        int RTT_prev ;
        int RTT_goodcount ;
        int F_counting ;
        int W_used ; 
        int W_timed ;
        int F_full ; 
        int Backoffs ;

        int control_increase_ ; /* If true, don't increase cwnd if sender */
                                /*  is not window-limited.  */
        int prev_highest_ack_ ; /* Used to determine if sender is */
                                /*  window-limited.  */
};

/* TCP Reno */
class RenoTcpAgent : public virtual TcpAgent {
 public:
        RenoTcpAgent();
        virtual int window();
        virtual double windowd();
        virtual void recv(Packet *pkt, Handler*);
        virtual void timeout(int tno);
        virtual void dupack_action();
 protected:
        int allow_fast_retransmit(int last_cwnd_action_);
        unsigned int dupwnd_;
};

/* TCP New Reno */
class NewRenoTcpAgent : public virtual RenoTcpAgent {
 public:
        NewRenoTcpAgent();
        virtual void recv(Packet *pkt, Handler*);
        virtual void partialnewack_helper(Packet* pkt);
        virtual void dupack_action();
 protected:
        int newreno_changes_;   /* 0 for fixing unnecessary fast retransmits */
                                /* 1 for additional code from Allman, */
                                /* to implement other algorithms from */
                                /* Hoe's paper, including sending a new */
                                /* packet for every two duplicate ACKs. */
                                /* The default is set to 0. */
        int newreno_changes1_;  /* Newreno_changes1_ set to 0 gives the */
                                /* Slow-but-Steady variant of NewReno from */
                                /* RFC 2582, with the retransmit timer reset */
                                /* after each partial new ack. */  
                                /* Newreno_changes1_ set to 1 gives the */
                                /* Impatient variant of NewReno from */
                                /* RFC 2582, with the retransmit timer reset */
                                /* only for the first partial new ack. */
                                /* The default is set to 0 */
        void partialnewack(Packet *pkt);
        int allow_fast_retransmit(int last_cwnd_action_);
        int acked_, new_ssthresh_;  /* used if newreno_changes_ == 1 */
        double ack2_, ack3_, basertt_; /* used if newreno_changes_ == 1 */
        int firstpartial_;      /* For the first partial ACK. */ 
        int partial_window_deflation_; /* 0 if set cwnd to ssthresh upon */
                                       /* partial new ack (default) */
                                       /* 1 if deflate (cwnd + dupwnd) by */
                                       /* amount of data acked */
                                       /* "Partial window deflation" is */
                                       /* discussed in RFC 2582. */
        int exit_recovery_fix_;  /* 0 for setting cwnd to ssthresh upon */
                                 /* leaving fast recovery (default) */
                                 /* 1 for setting cwnd to min(ssthresh, */
                                 /* amnt. of data in network) when leaving */
};

/* TCP vegas (VegasTcpAgent) */
class VegasTcpAgent : public virtual TcpAgent {
 public:
        VegasTcpAgent();
        ~VegasTcpAgent();
        virtual void recv(Packet *pkt, Handler *);
        virtual void timeout(int tno);
protected:
        double vegastime() {
                return(Scheduler::instance().clock() - firstsent_);
        }
        virtual void output(int seqno, int reason = 0);
        virtual void recv_newack_helper(Packet*);
        int vegas_expire(Packet*); 
        void reset();
        void vegas_inflate_cwnd(int win, double current_time);

        virtual void delay_bind_init_all();
        virtual int delay_bind_dispatch(const char *varName, const char *localName, TclObject *tracer);

        double t_cwnd_changed_; // last time cwnd changed
        double firstrecv_;      // time recv the 1st ack

        int    v_alpha_;        // vegas thruput thresholds in pkts
        int    v_beta_;                 

        int    v_gamma_;        // threshold to change from slow-start to
                                // congestion avoidance, in pkts

        int    v_slowstart_;    // # of pkts to send after slow-start, deflt(2)
        int    v_worried_;      // # of pkts to chk after dup ack (1 or 2)

        double v_timeout_;      // based on fine-grained timer
        double v_rtt_;          
        double v_sa_;           
        double v_sd_;   

        int    v_cntRTT_;       // # of rtt measured within one rtt
        double v_sumRTT_;       // sum of rtt measured within one rtt

        double v_begtime_;      // tagged pkt sent
        int    v_begseq_;       // tagged pkt seqno

        double* v_sendtime_;    // each unacked pkt's sendtime is recorded.
        int*   v_transmits_;    // # of retx for an unacked pkt

        int    v_maxwnd_;       // maxwnd size for v_sendtime_[]
        double v_newcwnd_;      // record un-inflated cwnd

        double v_baseRTT_;      // min of all rtt

        double v_incr_;         // amount cwnd is increased in the next rtt
        int    v_inc_flag_;     // if cwnd is allowed to incr for this rtt

        double v_actual_;       // actual send rate (pkt/s; needed for tcp-rbp)

        int ns_vegas_fix_level_;   // see comment at end of tcp-vegas.cc for details of fixes
};

// Local Variables:
// mode:c++
// End:

#endif

---