tcp-sink.cc

ns2.31下的UWB（Ultra WideBand）实现

/* -*-	Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
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 *	This product includes software developed by the Computer Systems
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/* 8/02 Tom Kelly - Dynamic resizing of seen buffer */

#include "flags.h"
#include "ip.h"
#include "tcp-sink.h"
#include "hdr_qs.h"
// Dapeng
extern int global_flowid;
extern int flow_to_tag[];

static class TcpSinkClass : public TclClass {
public:
	TcpSinkClass() : TclClass("Agent/TCPSink") {}
	TclObject* create(int, const char*const*) {
		return (new TcpSink(new Acker));
	}
} class_tcpsink;

Acker::Acker() : next_(0), maxseen_(0), wndmask_(MWM), ecn_unacked_(0), 
	ts_to_echo_(0), last_ack_sent_(0)
{
	seen_ = new int[MWS];
	memset(seen_, 0, (sizeof(int) * (MWS)));
}

void Acker::reset() 
{
	next_ = 0;
	maxseen_ = 0;
	memset(seen_, 0, (sizeof(int) * (wndmask_ + 1)));
}	

// dynamically increase the seen buffer as needed
// size must be a factor of two for the wndmask_ to work...
void Acker::resize_buffers(int sz) { 
	int* new_seen = new int[sz];
	int new_wndmask = sz - 1;
	
	if(!new_seen){
		fprintf(stderr, "Unable to allocate buffer seen_[%i]\n", sz);
		exit(1);
	}
	
	memset(new_seen, 0, (sizeof(int) * (sz)));
	
	for(int i = next_; i <= maxseen_+1; i++){
		new_seen[i & new_wndmask] = seen_[i&wndmask_];
	}
	
	delete[] seen_;
	seen_ = new_seen;      
	wndmask_ = new_wndmask;
	return; 
}

void Acker::update_ts(int seqno, double ts, int rfc1323)
{
	// update timestamp if segment advances with ACK.
        // Code changed by Andrei Gurtov.
        if (rfc1323 && seqno == last_ack_sent_ + 1)
               ts_to_echo_ = ts;
        else if (ts >= ts_to_echo_ && seqno <= last_ack_sent_ + 1)
               //rfc1323-bis, update timestamps from duplicate segments
               ts_to_echo_ = ts;
}

// returns number of bytes that can be "delivered" to application
// also updates the receive window (i.e. next_, maxseen, and seen_ array)
int Acker::update(int seq, int numBytes)
{
	bool just_marked_as_seen = FALSE;
	is_dup_ = FALSE;
	// start by assuming the segment hasn't been received before
	if (numBytes <= 0)
		printf("Error, received TCP packet size <= 0\n");
	int numToDeliver = 0;
	while(seq + 1 - next_ >= wndmask_) {
		// next_ is next packet expected; wndmask_ is the maximum
		// window size minus 1; if somehow the seqno of the
		// packet is greater than the one we're expecting+wndmask_,
		// then resize the buffer.
		resize_buffers((wndmask_+1)*2);
	}

	if (seq > maxseen_) {
		// the packet is the highest one we've seen so far
		int i;
		for (i = maxseen_ + 1; i < seq; ++i)
			seen_[i & wndmask_] = 0;
		// we record the packets between the old maximum and
		// the new max as being "unseen" i.e. 0 bytes of each
		// packet have been received
		maxseen_ = seq;
		seen_[maxseen_ & wndmask_] = numBytes;
		// store how many bytes have been seen for this packet
		seen_[(maxseen_ + 1) & wndmask_] = 0;
		// clear the array entry for the packet immediately
		// after this one
		just_marked_as_seen = TRUE;
		// necessary so this packet isn't confused as being a duplicate
	}
	int next = next_;
	if (seq < next) {
		// Duplicate packet case 1: the packet is to the left edge of
		// the receive window; therefore we must have seen it
		// before
#ifdef DEBUGDSACK
		printf("%f\t Received duplicate packet %d\n",Scheduler::instance().clock(),seq);
#endif
		is_dup_ = TRUE;
	}

	if (seq >= next && seq <= maxseen_) {
		// next is the left edge of the recv window; maxseen_
		// is the right edge; execute this block if there are
		// missing packets in the recv window AND if current
		// packet falls within those gaps

		if (seen_[seq & wndmask_] && !just_marked_as_seen) {
		// Duplicate case 2: the segment has already been
		// recorded as being received (AND not because we just
		// marked it as such)
			is_dup_ = TRUE;
#ifdef DEBUGDSACK
			printf("%f\t Received duplicate packet %d\n",Scheduler::instance().clock(),seq);
#endif
		}
		seen_[seq & wndmask_] = numBytes;
		// record the packet as being seen
		while (seen_[next & wndmask_]) {
			// this loop first gets executed if seq==next;
			// i.e., this is the next packet in order that
			// we've been waiting for.  the loop sets how
			// many bytes we can now deliver to the
			// application, due to this packet arriving
			// (and the prior arrival of any segments
			// immediately to the right)

			numToDeliver += seen_[next & wndmask_];
			++next;
		}
		next_ = next;
		// store the new left edge of the window
	}
	return numToDeliver;
}

TcpSink::TcpSink(Acker* acker) : Agent(PT_ACK), acker_(acker), save_(NULL),
	lastreset_(0.0)
{
	bytes_ = 0; 
	bind("bytes_", &bytes_);

	/*
	 * maxSackBlocks_ does wierd tracing things.
	 * don't make it delay-bound yet.
	 */
#if defined(TCP_DELAY_BIND_ALL) && 0
#else /* ! TCP_DELAY_BIND_ALL */
	bind("maxSackBlocks_", &max_sack_blocks_); // used only by sack
#endif /* TCP_DELAY_BIND_ALL */
	
	// Dapeng
	bind("nbytes_", &nbytes_);
	flow_id = global_flowid;
}

void
TcpSink::delay_bind_init_all()
{
        delay_bind_init_one("packetSize_");
        delay_bind_init_one("ts_echo_bugfix_");
	delay_bind_init_one("ts_echo_rfc1323_");
	delay_bind_init_one("bytes_"); // For throughput measurements in JOBS
        delay_bind_init_one("generateDSacks_"); // used only by sack
	delay_bind_init_one("qs_enabled_");
	delay_bind_init_one("RFC2581_immediate_ack_");
	delay_bind_init_one("ecn_syn_");
#if defined(TCP_DELAY_BIND_ALL) && 0
        delay_bind_init_one("maxSackBlocks_");
#endif /* TCP_DELAY_BIND_ALL */

	Agent::delay_bind_init_all();
}

int
TcpSink::delay_bind_dispatch(const char *varName, const char *localName, TclObject *tracer)
{
        if (delay_bind(varName, localName, "packetSize_", &size_, tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "ts_echo_bugfix_", &ts_echo_bugfix_, tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "ts_echo_rfc1323_", &ts_echo_rfc1323_, tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "generateDSacks_", &generate_dsacks_, tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "qs_enabled_", &qs_enabled_, tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "RFC2581_immediate_ack_", &RFC2581_immediate_ack_, tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "ecn_syn_", &ecn_syn_ ,tracer)) return TCL_OK;
#if defined(TCP_DELAY_BIND_ALL) && 0
        if (delay_bind(varName, localName, "maxSackBlocks_", &max_sack_blocks_, tracer)) return TCL_OK;
#endif /* TCP_DELAY_BIND_ALL */

        return Agent::delay_bind_dispatch(varName, localName, tracer);
}

void Acker::append_ack(hdr_cmn*, hdr_tcp*, int) const
{
}

void Acker::update_ecn_unacked(int value)
{
	ecn_unacked_ = value;
}

int TcpSink::command(int argc, const char*const* argv)
{
	if (argc == 2) {
		if (strcmp(argv[1], "reset") == 0) {
			reset();
			return (TCL_OK);
		}
		if (strcmp(argv[1], "resize_buffers") == 0) {
			// no need for this as seen buffer set dynamically
			fprintf(stderr,"DEPRECIATED: resize_buffers\n");
			return (TCL_OK);
		}
	}

	return (Agent::command(argc, argv));
}

void TcpSink::reset() 
{
	acker_->reset();	
	save_ = NULL;
	lastreset_ = Scheduler::instance().clock(); /* W.N. - for detecting */
				/* packets from previous incarnations */
}

void TcpSink::ack(Packet* opkt)
{
	Packet* npkt = allocpkt();
	// opkt is the "old" packet that was received
	// npkt is the "new" packet being constructed (for the ACK)
	double now = Scheduler::instance().clock();

	hdr_tcp *otcp = hdr_tcp::access(opkt);
	hdr_ip *oiph = hdr_ip::access(opkt);
	hdr_tcp *ntcp = hdr_tcp::access(npkt);

	// Dapeng
	flow_id = hdr_cmn::access(opkt)->_flowid_;

	if (qs_enabled_) {
		// QuickStart code from Srikanth Sundarrajan.
		hdr_qs *oqsh = hdr_qs::access(opkt);
		hdr_qs *nqsh = hdr_qs::access(npkt);
	        if (otcp->seqno() == 0 && oqsh->flag() == QS_REQUEST) {
	                nqsh->flag() = QS_RESPONSE;
	                nqsh->ttl() = (oiph->ttl() - oqsh->ttl()) % 256;
	                nqsh->rate() = oqsh->rate(); 
	        }
	        else {
	                nqsh->flag() = QS_DISABLE;
	        }
	}


	// get the tcp headers
	ntcp->seqno() = acker_->Seqno();
	// get the cumulative sequence number to put in the ACK; this
	// is just the left edge of the receive window - 1
	ntcp->ts() = now;
	// timestamp the packet

	if (ts_echo_bugfix_)  /* TCP/IP Illustrated, Vol. 2, pg. 870 */
		ntcp->ts_echo() = acker_->ts_to_echo();
	else
		ntcp->ts_echo() = otcp->ts();
	// echo the original's time stamp

	hdr_ip* oip = hdr_ip::access(opkt);
	hdr_ip* nip = hdr_ip::access(npkt);
	// get the ip headers
	nip->flowid() = oip->flowid();
	// copy the flow id
	
	hdr_flags* of = hdr_flags::access(opkt);
	hdr_flags* nf = hdr_flags::access(npkt);
	hdr_flags* sf;
	if (save_ != NULL)
		sf = hdr_flags::access(save_);
	else 
		sf = 0;
		// Look at delayed packet being acked. 
	if ( (sf != 0 && sf->cong_action()) || of->cong_action() ) 
		// Sender has responsed to congestion. 
		acker_->update_ecn_unacked(0);
	if ( (sf != 0 && sf->ect() && sf->ce())  || 
			(of->ect() && of->ce()) )
		// New report of congestion.  
		acker_->update_ecn_unacked(1);
	if ( (sf != 0 && sf->ect()) || of->ect() )
		// Set EcnEcho bit.  
		nf->ecnecho() = acker_->ecn_unacked();
	if (!of->ect() && of->ecnecho() ||
		(sf != 0 && !sf->ect() && sf->ecnecho()) ) {
		 // This is the negotiation for ECN-capability.
		 // We are not checking for of->cong_action() also. 
		 // In this respect, this does not conform to the 
		 // specifications in the internet draft 
		nf->ecnecho() = 1;
		if (ecn_syn_) 
			nf->ect() = 1;
	}
	acker_->append_ack(hdr_cmn::access(npkt),
			   ntcp, otcp->seqno());
	add_to_ack(npkt);
	// the above function is used in TcpAsymSink

        // Andrei Gurtov
        acker_->last_ack_sent_ = ntcp->seqno();
        // printf("ACK %d ts %f\n", ntcp->seqno(), ntcp->ts_echo());

	// Dapeng
	hdr_cmn::access(npkt)->_flowid_ = flow_id;
        hdr_cmn::access(npkt)->_tag_ = -1;
	
	send(npkt, 0);
	// send it
}

void TcpSink::add_to_ack(Packet*)
{
	return;
}


void TcpSink::recv(Packet* pkt, Handler*)
{
	int numToDeliver;
	int numBytes = hdr_cmn::access(pkt)->size();
	// number of bytes in the packet just received
	hdr_tcp *th = hdr_tcp::access(pkt);
	/* W.N. Check if packet is from previous incarnation */
	if (th->ts() < lastreset_) {
		// Remove packet and do nothing
		Packet::free(pkt);
		return;
	}
	acker_->update_ts(th->seqno(),th->ts(),ts_echo_rfc1323_);
	// update the timestamp to echo
	
      	numToDeliver = acker_->update(th->seqno(), numBytes);