6 files changed, 61 insertions(+), 3 deletions(-)

M ip/devip.c
M ip/icmp.c
M ip/il.c
M ip/ip.h
M ip/tcp.c
M ip/udp.c

@@ 1084,6 1084,7 @@ Fsprotoclone(Proto *p, char *user)
 {
 	Conv *c, **pp, **ep;
 
+retry:
 	c = nil;
 	ep = &p->conv[p->nc];
 	for(pp = p->conv; pp < ep; pp++) {


@@ 1120,6 1121,8 @@ Fsprotoclone(Proto *p, char *user)
 		}
 	}
 	if(pp >= ep) {
+		if(p->gc != nil && (*p->gc)(p))
+			goto retry;
 		return nil;
 	}
 

@@ 465,6 465,7 @@ icmpinit(Fs *fs)
 	icmp->stats = icmpstats;
 	icmp->ctl = nil;
 	icmp->advise = icmpadvise;
+	icmp->gc = nil;
 	icmp->ipproto = IP_ICMPPROTO;
 	icmp->nc = 16;
 	icmp->ptclsize = 0;

@@ 1341,6 1341,7 @@ ilinit(Fs *f)
 	il->advise = iladvise;
 	il->stats = ilxstats;
 	il->inuse = ilinuse;
+	il->gc = nil;
 	il->ipproto = IP_ILPROTO;
 	il->nc = Nchans;
 	il->ptclsize = sizeof(Ilcb);

@@ 27,7 27,7 @@ enum
 	Maxproto=	20,
 	Nhash=		64,
 	Maxincall=	5,
-	Nchans=		256,
+	Nchans=		512,
 	MAClen=		16,		/* longest mac address */
 
 	MAXTTL=		255,


@@ 218,6 218,7 @@ struct Proto
 	int		(*local)(Conv*, char*, int);
 	int		(*remote)(Conv*, char*, int);
 	int		(*inuse)(Conv*);
+	int		(*gc)(Proto*);	/* returns true if any conversations are freed */
 
 	Fs		*f;		/* file system this proto is part of */
 	Conv		**conv;		/* array of conversations */

@@ 123,7 123,7 @@ struct	Tcp
 	ushort	wnd;
 	ushort	urg;
 	ushort	mss;
-        ushort  len;  /* size of data */
+        ushort  len;	/* size of data */
 };
 
 typedef struct Reseq Reseq;


@@ 188,6 188,7 @@ struct Tcpctl
 	int	mdev;			/* Mean deviation of round trip */
 	int	kacounter;		/* count down for keep alive */
 	uint	sndsyntime;		/* time syn sent */
+	ulong	time;			/* time Finwait2 or Syn_received was sent */
 
 	Tcphdr	protohdr;		/* prototype header */
 };


@@ 1340,6 1341,7 @@ tcpiput(Proto *tcp, uchar*, Block *bp)
 		if(seg.flags & SYN) {
 			procsyn(s, &seg);
 			tcpsndsyn(tcb);
+			tcb->time = msec;
 			tcpsetstate(s, Syn_received);
 			if(length != 0 || (seg.flags & FIN))
 				break;


@@ 1365,8 1367,10 @@ tcpiput(Proto *tcp, uchar*, Block *bp)
 				tcpsynackrtt(s);
 				tcpsetstate(s, Established);
 			}
-			else
+			else {
+				tcb->time = msec;
 				tcpsetstate(s, Syn_received);
+			}
 
 			if(length != 0 || (seg.flags & FIN))
 				break;


@@ 1460,6 1464,7 @@ tcpiput(Proto *tcp, uchar*, Block *bp)
 				tcphalt(tpriv, &tcb->rtt_timer);
 				tcphalt(tpriv, &tcb->acktimer);
 				tcpsetkacounter(tcb);
+				tcb->time = msec;
 				tcpsetstate(s, Finwait2);
 				tcb->katimer.start = MSL2 * (1000 / MSPTICK);
 				tcpgo(tpriv, &tcb->katimer);


@@ 2238,6 2243,51 @@ tcpstats(Proto *tcp, char *buf, int len)
 		tpriv->tstats.OutRsts);
 }
 
+/*
+ *  garbage collect any stale conversations:
+ *	- SYN received but no SYN-ACK after 5 seconds (could be the SYN attack)
+ *	- Finwait2 after 5 minutes
+ *
+ *  this is called whenever we run out of channels.  Both checks are
+ *  of questionable validity so we try to use them only when we're
+ *  up against the wall.
+ */
+int
+tcpgc(Proto *tcp)
+{
+	Conv *c, **pp, **ep;
+	int n;
+	Tcpctl *tcb;
+
+
+	n = 0;
+	ep = &tcp->conv[tcp->nc];
+	for(pp = tcp->conv; pp < ep; pp++) {
+		c = *pp;
+		if(c == nil)
+			break;
+		if(!canqlock(c))
+			continue;
+		tcb = (Tcpctl*)c->ptcl;
+		switch(tcb->state){
+		case Syn_received:
+			if(msec - tcb->time > 5000){
+				localclose(c, "timed out");
+				n++;
+			}
+			break;
+		case Finwait2:
+			if(msec - tcb->time > 5*60*1000){
+				localclose(c, "timed out");
+				n++;
+			}
+			break;
+		}
+		qunlock(c);
+	}
+	return n;
+}
+
 void
 tcpinit(Fs *fs)
 {


@@ 2258,6 2308,7 @@ tcpinit(Fs *fs)
 	tcp->advise = tcpadvise;
 	tcp->stats = tcpstats;
 	tcp->inuse = tcpinuse;
+	tcp->gc = tcpgc;
 	tcp->ipproto = IP_TCPPROTO;
 	tcp->nc = Nchans;
 	tcp->ptclsize = sizeof(Tcpctl);

@@ 497,6 497,7 @@ udpinit(Fs *fs)
 	udp->rcv = udpiput;
 	udp->advise = udpadvise;
 	udp->stats = udpstats;
+	udp->gc = nil;
 	udp->ipproto = IP_UDPPROTO;
 	udp->nc = Nchans;
 	udp->ptclsize = sizeof(Udpcb);