From 60a9b49c675c8ab381d1bec8bef4b761df863a0a Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 18 Nov 1998 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1998-11-18

---
 ip/ip.h   |  7 +++++
 ip/rudp.c | 81 ++++++++++++++++++++++++++++++++++++-------------------
 ip/tcp.c  | 75 ++++++++++++++++++++++++++++++++++++++++-----------
 3 files changed, 119 insertions(+), 44 deletions(-)

diff --git a/ip/ip.h b/ip/ip.h
index 21cdb87e09e1597161adaa123243e303bf563414..1f7eacd25ddd2b6557baa47b7272a96207392e43 100644
--- a/ip/ip.h
+++ b/ip/ip.h
@@ -12,6 +12,7 @@ typedef struct	Ipmux	Ipmux;
 typedef struct	IProuter IProuter;
 typedef struct	Ipifc	Ipifc;
 typedef struct	Log	Log;
+typedef struct	Ifclog	Ifclog;
 typedef struct	Medium	Medium;
 typedef struct	Proto	Proto;
 typedef struct	Pstate	Pstate;
@@ -258,6 +259,7 @@ struct Fs
 	Route	*queue;			/* used as temp when reinjecting routes */
 
 	Log	*alog;
+	Ifclog	*ilog;
 };
 
 int	Fsconnected(Conv*, char*);
@@ -302,6 +304,11 @@ void	netlogclose(Fs*);
 char*	netlogctl(Fs*, char*, int);
 long	netlogread(Fs*, void*, ulong, long);
 void	netlog(Fs*, int, char*, ...);
+void	ifcloginit(Fs*);
+long	ifclogread(Fs*, Chan *,void*, ulong, long);
+void	ifclog(Fs*, uchar *, int);
+void	ifclogopen(Fs*, Chan*);
+void	ifclogclose(Fs*, Chan*);
 
 /*
  *  iproute.c
diff --git a/ip/rudp.c b/ip/rudp.c
index e296122c18f41480d2a0da7703ace09906778f99..fcf1a1a4f2505c681513c6908e496fd3d388d120 100644
--- a/ip/rudp.c
+++ b/ip/rudp.c
@@ -161,10 +161,6 @@ struct Rudppriv
 static ulong generation = 0;
 static Rendez rend;
 
-/* Used only for debugging */
-static ushort drop = 0;
-static ushort drop_rate = 10;
-
 /*
  *  protocol specific part of Conv
  */
@@ -173,6 +169,7 @@ struct Rudpcb
 {
 	QLock;
 	uchar	headers;
+	uchar	randdrop;
 	Reliable *r;
 };
 
@@ -261,6 +258,15 @@ rudpclose(Conv *c)
 	Rudpcb *ucb;
 	Reliable *r, *nr;
 
+	/* force out any delayed acks */
+	ucb = (Rudpcb*)c->ptcl;
+	qlock(ucb);
+	for(r = ucb->r; r; r = r->next){
+		if(r->acksent != r->rcvseq)
+			relsendack(c, r);
+	}
+	qunlock(ucb);
+
 	qclose(c->rq);
 	qclose(c->wq);
 	qclose(c->eq);
@@ -269,10 +275,12 @@ rudpclose(Conv *c)
 	c->lport = 0;
 	c->rport = 0;
 
-	ucb = (Rudpcb*)c->ptcl;
 	ucb->headers = 0;
+	ucb->randdrop = 0;
 	qlock(ucb);
 	for(r = ucb->r; r; r = nr){
+		if(r->acksent != r->rcvseq)
+			relsendack(c, r);
 		nr = r->next;
 		relhangup(c, r);
 		free(r);
@@ -284,6 +292,21 @@ rudpclose(Conv *c)
 	unlock(c);
 }
 
+/*
+ *  randomly don't send packets
+ */
+static void
+doipoput(Conv *c, Fs *f, Block *bp, int x, int ttl)
+{
+	Rudpcb *ucb;
+
+	ucb = (Rudpcb*)c->ptcl;
+	if(ucb->randdrop && nrand(10) == 1)
+		freeblist(bp);
+	else
+		ipoput(f, bp, x, ttl);
+}
+
 int
 flow(Reliable *r)
 {
@@ -411,7 +434,7 @@ rudpkick(Conv *c, int)
 	DPRINT("sent: %lud/%lud, %lud/%lud\n", 
 		r->sndseq, r->sndgen, r->rcvseq, r->rcvgen);
 
-	ipoput(f, bp, 0, c->ttl);
+	doipoput(c, f, bp, 0, c->ttl);
 
 	/* flow control of sorts */
 	qlock(&r->lock);
@@ -593,6 +616,9 @@ rudpctl(Conv *c, char **f, int n)
 		} else if(strcmp(f[0], "headers") == 0){
 			ucb->headers = 6;
 			return nil;
+		} else if(strcmp(f[0], "randdrop") == 0){
+			ucb->randdrop = 1;
+			return nil;
 		}
 	}
 	return "unknown control request";
@@ -802,6 +828,19 @@ reliput(Conv *c, Block *bp, uchar *addr, ushort port)
 	DPRINT("rcvd %lud/%lud, %lud/%lud, r->sndgen = %lud\n", 
 		seq, sgen, ack, agen, r->sndgen);
 
+	/* make sure we're not talking to a new remote side */
+	if(r->rcvgen != sgen){
+		if(seq != 1)
+			return -1;
+
+		/* new connection */
+		if(r->rcvgen != 0){
+			DPRINT("new con r->rcvgen = %lud, sgen = %lud\n", r->rcvgen, sgen);
+			relhangup(c, r);
+		}
+		r->rcvgen = sgen;
+	}
+
 	/* dequeue acked packets */
 	if(ack && agen == r->sndgen){
 		ackreal = 0;
@@ -833,29 +872,10 @@ reliput(Conv *c, Block *bp, uchar *addr, ushort port)
 		
 	}
 
-	/* make sure we're not talking to a new remote side */
-	if(r->rcvgen != sgen){
-		if(seq != 1)
-			return -1;
-
-		/* new connection */
-		if(r->rcvgen != 0){
-			DPRINT("new con r->rcvgen = %lud, sgen = %lud\n", r->rcvgen, sgen);
-			relhangup(c, r);
-		}
-		r->rcvgen = sgen;
-	}
-
 	/* no message or input queue full */
 	if(seq == 0 || qfull(c->rq))
 		return -1;
 
-	if(DEBUG && ++drop == drop_rate){
-		DPRINT("drop pkt on purpose\n");
-		drop = 0;
-		return -1;
-	}
-
 	/* refuse out of order delivery */
 	if(seq != NEXTSEQ(r->rcvseq)){
 		relsendack(c, r);	/* tell him we got it already */
@@ -913,16 +933,21 @@ relsendack(Conv *c, Reliable *r)
 	hnputs(uh->udpcksum, ptclcsum(bp, UDP_IPHDR, UDP_RHDRSIZE));
 
 	DPRINT("sendack: %lud/%lud, %lud/%lud\n", 0L, r->sndgen, r->rcvseq, r->rcvgen);
-	ipoput(f, bp, 0, c->ttl);
+	doipoput(c, f, bp, 0, c->ttl);
 }
 
 /*
  *  called with ucb locked (and c locked if user initiated close)
  */
 void
-relhangup(Conv *, Reliable *r)
+relhangup(Conv *c, Reliable *r)
 {
+	int n;
 	Block *bp;
+	char hup[ERRLEN];
+
+	n = snprint(hup, sizeof(hup), "hangup %I!%d", r->addr, r->port);
+	qproduce(c->eq, hup, n);
 
 	/*
 	 *  dump any unacked outgoing messages
@@ -965,5 +990,5 @@ relrexmit(Conv *c, Reliable *r)
 	upriv->rxmits++;
 	np = copyblock(r->unacked, blocklen(r->unacked));
 	DPRINT("rxmit r->ackrvcd+1 = %lud\n", r->ackrcvd+1);
-	ipoput(f, np, 0, c->ttl);
+	doipoput(c, f, np, 0, c->ttl);
 }
diff --git a/ip/tcp.c b/ip/tcp.c
index e1684c13153cb8e1f4570c8d0cc3d47a944d0c9c..09a25012077aeb7e7029cc0c34bba64a1bc2183b 100644
--- a/ip/tcp.c
+++ b/ip/tcp.c
@@ -38,6 +38,7 @@ enum
 	MSPTICK		= 50,		/* Milliseconds per timer tick */
 	DEF_MSS		= 1024,		/* Default mean segment */
 	DEF_RTT		= 150,		/* Default round trip */
+	DEF_KAT		= 10000,	/* Default keep alive trip in ms */
 	TCP_LISTEN	= 0,		/* Listen connection */
 	TCP_CONNECT	= 1,		/* Outgoing connection */
 
@@ -171,11 +172,11 @@ struct Tcpctl
 	Timer	timer;			/* Activity timer */
 	Timer	acktimer;		/* Acknowledge timer */
 	Timer	rtt_timer;		/* Round trip timer */
+	Timer	katimer;		/* keep alive timer */
 	ulong	rttseq;			/* Round trip sequence */
 	int	srtt;			/* Shortened round trip */
 	int	mdev;			/* Mean deviation of round trip */
 	int	kacounter;		/* count down for keep alive */
-	int	f2counter;		/* count down for finwait2 state */
 	uint	sndsyntime;		/* time syn sent */
 
 	Tcphdr	protohdr;		/* prototype header */
@@ -237,6 +238,7 @@ void	tcptimeout(void*);
 void	tcpsndsyn(Tcpctl*);
 void	tcprcvwin(Conv*);
 void	tcpacktimer(Conv*);
+void	tcpkeepalive(Conv*);
 
 void
 tcpsetstate(Conv *s, uchar newstate)
@@ -554,6 +556,7 @@ localclose(Conv *s, char *reason)	 /*  called with tcb locked */
 	tcphalt(tpriv, &tcb->timer);
 	tcphalt(tpriv, &tcb->rtt_timer);
 	tcphalt(tpriv, &tcb->acktimer);
+	tcphalt(tpriv, &tcb->katimer);
 
 	/* Flush reassembly queue; nothing more can arrive */
 	for(rp = tcb->reseq; rp != nil; rp = rp1) {
@@ -594,6 +597,10 @@ inittcpctl(Conv *s)
 	tcb->acktimer.start = TCP_ACK / MSPTICK;
 	tcb->acktimer.func = tcpacktimer;
 	tcb->acktimer.arg = s;
+	tcb->kacounter = 0;
+	tcb->katimer.start = DEF_KAT / MSPTICK;
+	tcb->katimer.func = tcpkeepalive;
+	tcb->katimer.arg = s;
 
 	/* create a prototype(pseudo) header */
 	if(ipcmp(s->laddr, IPnoaddr) == 0)
@@ -1007,8 +1014,6 @@ update(Conv *s, Tcp *seg)
 	tpriv = s->p->priv;
 	tcb = (Tcpctl*)s->ptcl;
 
-	tcb->kacounter = MAXBACKOFF;	/* keep alive count down */
-
 	if(seq_gt(seg->ack, tcb->snd.nxt)) {
 		tcb->flags |= FORCE;
 		return;
@@ -1224,6 +1229,9 @@ tcpiput(Proto *tcp, uchar*, Block *bp)
 	tcb = (Tcpctl*)s->ptcl;
 	qlock(tcb);
 
+	if(tcb->kacounter > 0)
+		tcb->kacounter = MAXBACKOFF;
+
 	switch(tcb->state) {
 	case Closed:
 		sndrst(tcp, source, dest, length, &seg);
@@ -1343,9 +1351,9 @@ tcpiput(Proto *tcp, uchar*, Block *bp)
 		case Finwait1:
 			update(s, &seg);
 			if(tcb->sndcnt == 0){
-				tcb->f2counter = MAXBACKOFF;
+				tcb->kacounter = MAXBACKOFF;
 				tcpsetstate(s, Finwait2);
-				tcb->timer.start = MSL2 * (1000 / MSPTICK);
+				tcb->katimer.start = MSL2 * (1000 / MSPTICK);
 				tcpgo(tpriv, &tcb->timer);
 			}
 			break;
@@ -1686,6 +1694,8 @@ tcpoutput(Conv *s)
 		}
 
 		tpriv->tstats.tcpOutSegs++;
+		if(tcb->kacounter > 0)
+			tcpgo(tpriv, &tcb->katimer);
 		ipoput(f, hbp, 0, s->ttl);
 	}
 }
@@ -1694,7 +1704,7 @@ tcpoutput(Conv *s)
  *  the BSD convention (hack?) for keep alives.  resend last uchar acked.
  */
 void
-tcpkeepalive(Conv *s)
+tcpsendka(Conv *s)
 {
 	Tcp seg;
 	Tcpctl *tcb;
@@ -1730,6 +1740,47 @@ tcpkeepalive(Conv *s)
 	ipoput(s->p->f, hbp, 0, s->ttl);
 }
 
+/*
+ *  if we've timed out, close the connection
+ *  otherwise, send a keepalive and restart the timer
+ */
+void
+tcpkeepalive(Conv *s)
+{
+	Tcpctl *tcb;
+
+	tcb = (Tcpctl*)s->ptcl;
+	if(--(tcb->kacounter) <= 0)
+		localclose(s, Etimedout);
+	else {
+		qlock(tcb);
+		tcpsendka(s);
+		qunlock(tcb);
+		tcpgo(s->p->priv, &tcb->katimer);
+	}
+}
+
+/*
+ *  start keepalive timer
+ */
+char*
+tcpstartka(Conv *s, char **f, int n)
+{
+	Tcpctl *tcb;
+	int x;
+
+	tcb = (Tcpctl*)s->ptcl;
+	if(n > 1){
+		x = atoi(f[1]);
+		if(x >= MSPTICK)
+			tcb->katimer.start = x/MSPTICK;
+	}
+	tcb->kacounter = MAXBACKOFF;
+	tcpgo(s->p->priv, &tcb->katimer);
+
+	return nil;
+}
+
 void
 tcprxmit(Conv *s)
 {
@@ -1782,16 +1833,6 @@ tcptimeout(void *arg)
 		}
 		tcprxmit(s);
 		break;
-	case Finwait2:
-		if(--(tcb->f2counter) <= 0)
-			localclose(s, Etimedout);
-		else {
-			qlock(tcb);
-			tcpkeepalive(s);
-			qunlock(tcb);
-			tcpgo(s->p->priv, &tcb->timer);
-		}
-		break;
 	case Time_wait:
 		localclose(s, nil);
 		break;
@@ -2001,6 +2042,8 @@ tcpctl(Conv* c, char** f, int n)
 {
 	if(n == 1 && strcmp(f[0], "hangup") == 0)
 		return tcphangup(c);
+	if(n >= 1 && strcmp(f[0], "keepalive") == 0)
+		return tcpstartka(c, f, n);
 	return "unknown control request";
 }