il.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

				ic->fasttimeout = 0;
				ic->rexmit = 0;
				goto established;
			}
			break;
		case Ilclose:
			if(ack == ic->start)
				ilhangup(s, "remote close");
			break;
		}
		freeblist(bp);
		break;
	case Ilestablished:
	established:
		switch(h->iltype) {
		case Ilsync:
			if(id != ic->rstart)
				ilhangup(s, "remote close");
			else
				ilsendctl(s, nil, Ilack, ic->next, ic->rstart, 0);
			freeblist(bp);	
			break;
		case Ildata:
			/*
			 * avoid consuming all the mount rpc buffers in the
			 * system.  if the input queue is too long, drop this
			 * packet.
			 */
			if (s->rq && qlen(s->rq) >= Maxrq) {
				priv->stats[DroppedMsgs]++;
				freeblist(bp);
				break;
			}

			ilackto(ic, ack, bp);
			iloutoforder(s, h, bp);
			ilpullup(s);
			break;
		case Ildataquery:
			ilackto(ic, ack, bp);
			iloutoforder(s, h, bp);
			ilpullup(s);
			ilsendctl(s, nil, Ilstate, ic->next, ic->recvd, h->ilspec);
			break;
		case Ilack:
			ilackto(ic, ack, bp);
			freeblist(bp);
			break;
		case Ilquery:
			ilackto(ic, ack, bp);
			ilsendctl(s, nil, Ilstate, ic->next, ic->recvd, h->ilspec);
			freeblist(bp);
			break;
		case Ilstate:
			if(ack >= ic->rttack)
				ic->rttack = 0;
			ilackto(ic, ack, bp);
			if(h->ilspec > Nqt)
				h->ilspec = 0;
			if(ic->qt[h->ilspec] > ack){
				ilrexmit(ic);
				ilsettimeout(ic);
			}
			freeblist(bp);
			break;
		case Ilclose:
			freeblist(bp);
			if(ack < ic->start || ack > ic->next) 
				break;
			ic->recvd = id;
			ilsendctl(s, nil, Ilclose, ic->next, ic->recvd, 0);
			ic->state = Ilclosing;
			ilsettimeout(ic);
			ilfreeq(ic);
			break;
		}
		break;
	case Illistening:
		freeblist(bp);
		break;
	case Ilclosing:
		switch(h->iltype) {
		case Ilclose:
			ic->recvd = id;
			ilsendctl(s, nil, Ilclose, ic->next, ic->recvd, 0);
			if(ack == ic->next)
				ilhangup(s, nil);
			break;
		default:
			break;
		}
		freeblist(bp);
		break;
	}
}

void
ilrexmit(Ilcb *ic)
{
	Ilhdr *h;
	Block *nb;
	Conv *c;
	ulong id;
	Ilpriv *priv;

	nb = nil;
	qlock(&ic->ackq);
	if(ic->unacked)
		nb = copyblock(ic->unacked, blocklen(ic->unacked));
	qunlock(&ic->ackq);

	if(nb == nil)
		return;

	h = (Ilhdr*)nb->rp;
	h->vihl = IP_VER4;

	h->iltype = Ildataquery;
	hnputl(h->ilack, ic->recvd);
	h->ilspec = ilnextqt(ic);
	h->ilsum[0] = 0;
	h->ilsum[1] = 0;
	hnputs(h->ilsum, ptclcsum(nb, IL_IPSIZE, nhgets(h->illen)));

	c = ic->conv;
	id = nhgetl(h->ilid);
	netlog(c->p->f, Logil, "il: rexmit %d %ud: %d %d: %i %d/%d\n", id, ic->recvd,
		ic->rexmit, ic->timeout,
		c->raddr, c->lport, c->rport);

	ilbackoff(ic);

	ipoput4(c->p->f, nb, 0, c->ttl, c->tos, c);

	/* statistics */
	ic->rxtot++;
	priv = c->p->priv;
	priv->rexmit++;
}

/* DEBUG */
void
ilprocess(Conv *s, Ilhdr *h, Block *bp)
{
	Ilcb *ic;

	ic = (Ilcb*)s->ptcl;

	USED(ic);
	netlog(s->p->f, Logilmsg, "%11s rcv %d/%d snt %d/%d pkt(%s id %d ack %d %d->%d) ",
		ilstates[ic->state],  ic->rstart, ic->recvd, ic->start, 
		ic->next, iltype[h->iltype], nhgetl(h->ilid), 
		nhgetl(h->ilack), nhgets(h->ilsrc), nhgets(h->ildst));

	_ilprocess(s, h, bp);

	netlog(s->p->f, Logilmsg, "%11s rcv %d snt %d\n", ilstates[ic->state], ic->recvd, ic->next);
}

void
ilhangup(Conv *s, char *msg)
{
	Ilcb *ic;
	int callout;

	netlog(s->p->f, Logil, "il: hangup! %I %d/%d: %s\n", s->raddr,
		s->lport, s->rport, msg?msg:"no reason");

	ic = (Ilcb*)s->ptcl;
	callout = ic->state == Ilsyncer;
	illocalclose(s);

	qhangup(s->rq, msg);
	qhangup(s->wq, msg);

	if(callout)
		Fsconnected(s, msg);
}

void
ilpullup(Conv *s)
{
	Ilcb *ic;
	Ilhdr *oh;
	Block *bp;
	ulong oid, dlen;
	Ilpriv *ipriv;

	ic = (Ilcb*)s->ptcl;
	if(ic->state != Ilestablished)
		return;

	qlock(&ic->outo);
	while(ic->outoforder) {
		bp = ic->outoforder;
		oh = (Ilhdr*)bp->rp;
		oid = nhgetl(oh->ilid);
		if(oid <= ic->recvd) {
			ic->outoforder = bp->list;
			freeblist(bp);
			continue;
		}
		if(oid != ic->recvd+1){
			ipriv = s->p->priv;
			ipriv->stats[OutOfOrder]++;
			break;
		}

		ic->recvd = oid;
		ic->outoforder = bp->list;

		bp->list = nil;
		dlen = nhgets(oh->illen)-IL_HDRSIZE;
		bp = trimblock(bp, IL_IPSIZE+IL_HDRSIZE, dlen);
		/*
		 * Upper levels don't know about multiple-block
		 * messages so copy all into one (yick).
		 */
		bp = concatblock(bp);
		if(bp == 0)
			panic("ilpullup");
		bp = packblock(bp);
		if(bp == 0)
			panic("ilpullup2");
		qpass(s->rq, bp);
	}
	qunlock(&ic->outo);
}

void
iloutoforder(Conv *s, Ilhdr *h, Block *bp)
{
	Ilcb *ic;
	uchar *lid;
	Block *f, **l;
	ulong id, newid;
	Ilpriv *ipriv;

	ipriv = s->p->priv;
	ic = (Ilcb*)s->ptcl;
	bp->list = nil;

	id = nhgetl(h->ilid);
	/* Window checks */
	if(id <= ic->recvd || id > ic->recvd+ic->window) {
		netlog(s->p->f, Logil, "il: message outside window %ud <%ud-%ud>: %i %d/%d\n",
			id, ic->recvd, ic->recvd+ic->window, s->raddr, s->lport, s->rport);
		freeblist(bp);
		return;
	}

	/* Packet is acceptable so sort onto receive queue for pullup */
	qlock(&ic->outo);
	if(ic->outoforder == nil)
		ic->outoforder = bp;
	else {
		l = &ic->outoforder;
		for(f = *l; f; f = f->list) {
			lid = ((Ilhdr*)(f->rp))->ilid;
			newid = nhgetl(lid);
			if(id <= newid) {
				if(id == newid) {
					ipriv->stats[DupMsg]++;
					ipriv->stats[DupBytes] += blocklen(bp);
					qunlock(&ic->outo);
					freeblist(bp);
					return;
				}
				bp->list = f;
				*l = bp;
				qunlock(&ic->outo);
				return;
			}
			l = &f->list;
		}
		*l = bp;
	}
	qunlock(&ic->outo);
}

void
ilsendctl(Conv *ipc, Ilhdr *inih, int type, ulong id, ulong ack, int ilspec)
{
	Ilhdr *ih;
	Ilcb *ic;
	Block *bp;
	int ttl, tos;

	bp = allocb(IL_IPSIZE+IL_HDRSIZE);
	bp->wp += IL_IPSIZE+IL_HDRSIZE;

	ih = (Ilhdr *)(bp->rp);
	ih->vihl = IP_VER4;

	/* Ip fields */
	ih->proto = IP_ILPROTO;
	hnputs(ih->illen, IL_HDRSIZE);
	ih->frag[0] = 0;
	ih->frag[1] = 0;
	if(inih) {
		hnputl(ih->dst, nhgetl(inih->src));
		hnputl(ih->src, nhgetl(inih->dst));
		hnputs(ih->ilsrc, nhgets(inih->ildst));
		hnputs(ih->ildst, nhgets(inih->ilsrc));
		hnputl(ih->ilid, nhgetl(inih->ilack));
		hnputl(ih->ilack, nhgetl(inih->ilid));
		ttl = MAXTTL;
		tos = DFLTTOS;
	}
	else {
		v6tov4(ih->dst, ipc->raddr);
		v6tov4(ih->src, ipc->laddr);
		hnputs(ih->ilsrc, ipc->lport);
		hnputs(ih->ildst, ipc->rport);
		hnputl(ih->ilid, id);
		hnputl(ih->ilack, ack);
		ic = (Ilcb*)ipc->ptcl;
		ic->acksent = ack;
		ic->acktime = NOW;
		ttl = ipc->ttl;
		tos = ipc->tos;
	}
	ih->iltype = type;
	ih->ilspec = ilspec;
	ih->ilsum[0] = 0;
	ih->ilsum[1] = 0;

	if(ilcksum)
		hnputs(ih->ilsum, ptclcsum(bp, IL_IPSIZE, IL_HDRSIZE));

if(ipc==nil)
	panic("ipc is nil caller is %.8lux", getcallerpc(&ipc));
if(ipc->p==nil)
	panic("ipc->p is nil");

	netlog(ipc->p->f, Logilmsg, "ctl(%s id %d ack %d %d->%d)\n",
		iltype[ih->iltype], nhgetl(ih->ilid), nhgetl(ih->ilack), 
		nhgets(ih->ilsrc), nhgets(ih->ildst));

	ipoput4(ipc->p->f, bp, 0, ttl, tos, ipc);
}

void
ilreject(Fs *f, Ilhdr *inih)
{
	Ilhdr *ih;
	Block *bp;

	bp = allocb(IL_IPSIZE+IL_HDRSIZE);
	bp->wp += IL_IPSIZE+IL_HDRSIZE;

	ih = (Ilhdr *)(bp->rp);
	ih->vihl = IP_VER4;

	/* Ip fields */
	ih->proto = IP_ILPROTO;
	hnputs(ih->illen, IL_HDRSIZE);
	ih->frag[0] = 0;
	ih->frag[1] = 0;
	hnputl(ih->dst, nhgetl(inih->src));
	hnputl(ih->src, nhgetl(inih->dst));
	hnputs(ih->ilsrc, nhgets(inih->ildst));
	hnputs(ih->ildst, nhgets(inih->ilsrc));
	hnputl(ih->ilid, nhgetl(inih->ilack));
	hnputl(ih->ilack, nhgetl(inih->ilid));
	ih->iltype = Ilclose;
	ih->ilspec = 0;
	ih->ilsum[0] = 0;
	ih->ilsum[1] = 0;

	if(ilcksum)
		hnputs(ih->ilsum, ptclcsum(bp, IL_IPSIZE, IL_HDRSIZE));

	ipoput4(f, bp, 0, MAXTTL, DFLTTOS, nil);
}

void
ilsettimeout(Ilcb *ic)
{
	ulong pt;

	pt = (ic->delay>>LogAGain)
		+ ic->unackedbytes/(ic->rate>>LogAGain)
		+ (ic->mdev>>(LogDGain-1))
		+ AckDelay;
	if(pt > MaxTimeout)
		pt = MaxTimeout;
	ic->timeout = NOW + pt;
}

void
ilbackoff(Ilcb *ic)
{
	ulong pt;
	int i;

	pt = (ic->delay>>LogAGain)
		+ ic->unackedbytes/(ic->rate>>LogAGain)
		+ (ic->mdev>>(LogDGain-1))
		+ AckDelay;
	for(i = 0; i < ic->rexmit; i++)
		pt = pt + (pt>>1);
	if(pt > MaxTimeout)
		pt = MaxTimeout;
	ic->timeout = NOW + pt;

	if(ic->fasttimeout)
		ic->timeout = NOW+Iltickms;

	ic->rexmit++;
}

// complain if two numbers not within an hour of each other
#define Tfuture (1000*60*60)
int
later(ulong t1, ulong t2, char *x)
{
	int dt;

	dt = t1 - t2;
	if(dt > 0) {
		if(x != nil && dt > Tfuture)
			print("%s: way future %d\n", x, dt);
		return 1;
	}
	if(dt < -Tfuture) {
		if(x != nil)
			print("%s: way past %d\n", x, -dt);
		return 1;
	}
	return 0;
}

void
ilackproc(void *x)
{
	Ilcb *ic;
	Conv **s, *p;
	Proto *il;

	il = x;

loop:
	tsleep(&up->sleep, return0, 0, Iltickms);
	for(s = il->conv; s && *s; s++) {
		p = *s;
		ic = (Ilcb*)p->ptcl;

		switch(ic->state) {
		case Ilclosed:
		case Illistening:
			break;
		case Ilclosing:
			if(later(NOW, ic->timeout, "timeout0")) {
				if(ic->rexmit > MaxRexmit){
					ilhangup(p, nil);
					break;
				}
				ilsendctl(p, nil, Ilclose, ic->next, ic->recvd, 0);
				ilbackoff(ic);
			}
			break;

		case Ilsyncee:
		case Ilsyncer:
			if(later(NOW, ic->timeout, "timeout1")) {
				if(ic->rexmit > MaxRexmit){
					ilhangup(p, etime);
					break;
				}
				ilsendctl(p, nil, Ilsync, ic->start, ic->recvd, 0);
				ilbackoff(ic);
			}
			break;

		case Ilestablished:
			if(ic->recvd != ic->acksent)
			if(later(NOW, ic->acktime, "acktime"))
				ilsendctl(p, nil, Ilack, ic->next, ic->recvd, 0);

			if(later(NOW, ic->querytime, "querytime")){
				if(later(NOW, ic->lastrecv+DeathTime, "deathtime")){
					netlog(il->f, Logil, "il: hangup: deathtime\n");
					ilhangup(p, etime);
					break;
				}
				ilsendctl(p, nil, Ilquery, ic->next, ic->recvd, ilnextqt(ic));
				ic->querytime = NOW + QueryTime;
			}

			if(ic->unacked != nil)
			if(later(NOW, ic->timeout, "timeout2")) {
				if(ic->rexmit > MaxRexmit){
					netlog(il->f, Logil, "il: hangup: too many rexmits\n");
					ilhangup(p, etime);
					break;
				}
				ilsendctl(p, nil, Ilquery, ic->next, ic->recvd, ilnextqt(ic));
				ic->rxquery++;
				ilbackoff(ic);
			}
			break;
		}
	}
	goto loop;
}

void
ilcbinit(Ilcb *ic)
{
	ic->start = nrand(0x1000000);
	ic->next = ic->start+1;
	ic->recvd = 0;
	ic->window = Defaultwin;
	ic->unackedbytes = 0;
	ic->unacked = nil;
	ic->outoforder = nil;
	ic->rexmit = 0;
	ic->rxtot = 0;
	ic->rxquery = 0;
	ic->qtx = 1;
	ic->fasttimeout = 0;

	/* timers */
	ic->delay = DefRtt<<LogAGain;
	ic->mdev = DefRtt<<LogDGain;
	ic->rate = DefByteRate<<LogAGain;
	ic->querytime = NOW + QueryTime;
	ic->lastrecv = NOW;	/* or we'll timeout right away */
	ilsettimeout(ic);
}

char*
ilstart(Conv *c, int type, int fasttimeout)
{
	Ilcb *ic;
	Ilpriv *ipriv;
	char kpname[KNAMELEN];

	ipriv = c->p->priv;

	if(ipriv->ackprocstarted == 0){
		qlock(&ipriv->apl);
		if(ipriv->ackprocstarted == 0){
			sprint(kpname, "#I%dilack", c->p->f->dev);
			kproc(kpname, ilackproc, c->p);
			ipriv->ackprocstarted = 1;
		}
		qunlock(&ipriv->apl);
	}

	ic = (Ilcb*)c->ptcl;
	ic->conv = c;

	if(ic->state != Ilclosed)
		return nil;

	ilcbinit(ic);

	if(fasttimeout){
		/* timeout if we can't connect quickly */
		ic->fasttimeout = 1;
		ic->timeout = NOW+Iltickms;
		ic->rexmit = MaxRexmit - 4;
	};

	switch(type) {
	default:
		netlog(c->p->f, Logil, "il: start: type %d\n", type);
		break;
	case IL_LISTEN:
		ic->state = Illistening;
		iphtadd(&ipriv->ht, c);
		break;
	case IL_CONNECT:
		ic->state = Ilsyncer;
		iphtadd(&ipriv->ht, c);
		ilsendctl(c, nil, Ilsync, ic->start, ic->recvd, 0);
		break;
	}

	return nil;
}

void
ilfreeq(Ilcb *ic)
{
	Block *bp, *next;

	qlock(&ic->ackq);
	for(bp = ic->unacked; bp; bp = next) {
		next = bp->list;
		freeblist(bp);
	}
	ic->unacked = nil;
	qunlock(&ic->ackq);

	qlock(&ic->outo);
	for(bp = ic->outoforder; bp; bp = next) {
		next = bp->list;
		freeblist(bp);
	}
	ic->outoforder = nil;
	qunlock(&ic->outo);
}

void
iladvise(Proto *il, Block *bp, char *msg)
{
	Ilhdr *h;
	Ilcb *ic;		
	uchar source[IPaddrlen], dest[IPaddrlen];
	ushort psource;
	Conv *s, **p;

	h = (Ilhdr*)(bp->rp);

	v4tov6(dest, h->dst);
	v4tov6(source, h->src);
	psource = nhgets(h->ilsrc);


	/* Look for a connection, unfortunately the destination port is missing */
	qlock(il);
	for(p = il->conv; *p; p++) {
		s = *p;
		if(s->lport == psource)
		if(ipcmp(s->laddr, source) == 0)
		if(ipcmp(s->raddr, dest) == 0){
			qunlock(il);
			ic = (Ilcb*)s->ptcl;
			switch(ic->state){
			case Ilsyncer:
				ilhangup(s, msg);
				break;
			}
			freeblist(bp);
			return;
		}
	}
	qunlock(il);
	freeblist(bp);
}

int
ilnextqt(Ilcb *ic)
{
	int x;

	qlock(&ic->ackq);
	x = ic->qtx;
	if(++x > Nqt)
		x = 1;
	ic->qtx = x;
	ic->qt[x] = ic->next-1;	/* highest xmitted packet */
	ic->qt[0] = ic->qt[x];	/* compatibility with old implementations */
	qunlock(&ic->ackq);

	return x;
}

/* calculate scale constants that converts fast ticks to ms (more or less) */
static void
inittimescale(void)
{
	uvlong hz;

	fastticks(&hz);
	if(hz > 1000){
		scalediv = hz/1000;
		scalemul = 1;
	} else {
		scalediv = 1;
		scalemul = 1000/hz;
	}
}

void
ilinit(Fs *f)
{
	Proto *il;

	inittimescale();

	il = smalloc(sizeof(Proto));
	il->priv = smalloc(sizeof(Ilpriv));
	il->name = "il";
	il->connect = ilconnect;
	il->announce = ilannounce;
	il->state = ilstate;
	il->create = ilcreate;
	il->close = ilclose;
	il->rcv = iliput;
	il->ctl = nil;
	il->advise = iladvise;
	il->stats = ilxstats;
	il->inuse = ilinuse;
	il->gc = nil;
	il->ipproto = IP_ILPROTO;
	il->nc = scalednconv();
	il->ptclsize = sizeof(Ilcb);
	Fsproto(f, il);
}