From 66db0535ca71850f6d0617d444042cf38f6f1d13 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 23 Oct 1991 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1991-10-23

---
 port/devbit.c   |  2 +-
 port/devip.c    | 52 +++++++++++++++++++++++++++++++------------------
 port/ipdat.h    |  8 +++-----
 port/stil.c     | 28 +++++++++++++++++++-------
 port/stip.c     |  1 -
 port/tcpinput.c | 23 +++++-----------------
 6 files changed, 63 insertions(+), 51 deletions(-)

diff --git a/port/devbit.c b/port/devbit.c
index 1e4b77775f0b4f3160731446bf72929060df5d73..48f3d8e0ab50ef359ff4646254ab079a090344af 100644
--- a/port/devbit.c
+++ b/port/devbit.c
@@ -487,7 +487,7 @@ bitread(Chan *c, void *va, long n, ulong offset)
 		ws = 1<<(3-gscreen.ldepth);	/* pixels per byte */
 		l = (gscreen.r.max.x+ws-1)/ws - gscreen.r.min.x/ws;
 		t = offset-5*12;
-		miny = t/l;
+		miny = t/l;	/* unsigned computation */
 		maxy = (t+n)/l;
 		if(miny >= gscreen.r.max.y)
 			return 0;
diff --git a/port/devip.c b/port/devip.c
index 1ea2d848e4c65d7ed21253a4ef039981beb2c768..1918b6c0f8ac117914fe03becf43f3bc2300287b 100644
--- a/port/devip.c
+++ b/port/devip.c
@@ -225,6 +225,30 @@ ipclonecon(Chan *c)
 
 	base = ipconv[c->dev];
 	etab = &base[conf.ip];
+	for(new = base; new < etab; new++) {
+		new = ipincoming(c->dev);
+		if(new == 0)
+			error(Enodev);
+
+		c->qid.path = CHDIR|STREAMQID(new-base, ipchanqid);
+		devwalk(c, "ctl", 0, 0, streamgen);
+
+		streamopen(c, &ipinfo);
+		pushq(c->stream, new->stproto);
+		new->ref--;
+		return new;
+	}
+
+	error(Enodev);
+}
+
+Ipconv *
+ipincoming(int dev)
+{
+	Ipconv *base, *new, *etab;
+
+	base = ipconv[dev];
+	etab = &base[conf.ip];
 	for(new = base; new < etab; new++) {
 		if(new->ref == 0 && canqlock(new)) {
 			if(new->ref ||
@@ -234,18 +258,11 @@ ipclonecon(Chan *c)
 				continue;
 			}
 			new->ref++;
-			c->qid.path = CHDIR|STREAMQID(new-base, ipchanqid);
-			devwalk(c, "ctl", 0, 0, streamgen);
 			qunlock(new);
-
-			streamopen(c, &ipinfo);
-			pushq(c->stream, new->stproto);
-			new->ref--;
 			return new;
 		}	
 	}
-
-	error(Enodev);
+	return 0;
 }
 
 void
@@ -642,7 +659,7 @@ tcpstopen(Queue *q, Stream *s)
 }
 
 int
-tcp_havecon(Ipconv *s)
+iphavecon(Ipconv *s)
 {
 	return s->curlog;
 }
@@ -655,28 +672,25 @@ iplisten(Chan *c, Ipconv *s, Ipconv *base)
 	qlock(&s->listenq);
 
 	for(;;) {
-		sleep(&s->listenr, tcp_havecon, s);
-
-		/* Search for the new connection, clone the control channel and
-		 * return an open channel to the listener
-		 */
-		for(new = base, etab = &base[conf.ip]; new < etab; new++) {
-			if(new->psrc == s->psrc && new->pdst != 0 && 
-			   new->dst && (new->tcpctl.flags & CLONE) == 0) {
-				new->ref++;
+		sleep(&s->listenr, iphavecon, s);
 
+		new = base;
+ 		for(etab = &base[conf.ip]; new < etab; new++) {
+			if(new->newcon) {
 				/* Remove the listen channel reference */
 				streamclose(c);
 
 				s->curlog--;
+
 				/* Attach the control channel to the new connection */
+				new->newcon = 0;
 				c->qid.path = CHDIR|STREAMQID(new-base, ipchanqid);
 				devwalk(c, "ctl", 0, 0, streamgen);
 				streamopen(c, &ipinfo);
 				pushq(c->stream, new->stproto);
 				new->ref--;
-
 				qunlock(&s->listenq);
+
 				return;
 			}
 		}
diff --git a/port/ipdat.h b/port/ipdat.h
index a5afdd51411052df7b80b23388592390ee45aa98..8b9195e80e1c5a781d8a14ddc49655ea18bbc8b6 100644
--- a/port/ipdat.h
+++ b/port/ipdat.h
@@ -263,22 +263,19 @@ struct Ipconv
 	int 	ref;
 	Qinfo	*stproto;		/* Stream protocol for this device */
 	Ipaddr	dst;			/* Destination from connect */
-
 	Port	psrc;			/* Source port */
 	Port	pdst;			/* Destination port */
 
-	uchar	ptype;			/* Source port type */
 	Ipifc	*ipinterface;		/* Ip protocol interface */
 	Queue	*readq;			/* Pointer to upstream read q */
-
 	QLock	listenq;		/* List of people waiting incoming cons */
 	Rendez	listenr;		/* Some where to sleep while waiting */
-	Ipconv	*listen;
 		
 	char	err;			/* Async protocol error */
 	int	backlog;		/* Maximum number of waiting connections */
 	int	curlog;			/* Number of waiting connections */
-	int 	contype;
+	int 	newcon;			/* Flags that this is the start of a connection */
+
 	union {
 		Tcpctl	tcpctl;			/* Tcp control block */
 		Ilcb	ilctl;			/* Il control block */
@@ -476,6 +473,7 @@ int	seq_gt(int, int);
 void	appendb(Block **, Block *);
 Ipconv	*ip_conn(Ipconv *, Port, Port, Ipaddr dest, char proto);
 void	ipmkdir(Qinfo *, Dirtab *, Ipconv *);
+Ipconv	*ipincoming(Ipconv*);
 int	inb_window(Tcpctl *, int);
 Block	*htontcp(Tcp *, Block *, Tcphdr *);
 void	start_timer(Timer *);
diff --git a/port/stil.c b/port/stil.c
index 7962f033de43761b2277ac5550a8c9fdee2f3be1..4976d5a7fbf611c23dcd212eac3f51c003292d32 100644
--- a/port/stil.c
+++ b/port/stil.c
@@ -12,10 +12,9 @@
 #include 	"ipdat.h"
 
 #define DPRINT if(pip)print
-int ilcksum = 1;
-
-static int initseq = 25000;
-char *ilstate[] = { "Closed", "Syncer", "Syncee", "Established", "Listening", "Closing" };
+int 	ilcksum = 1;
+static 	int initseq = 25000;
+char	*ilstate[] = { "Closed", "Syncer", "Syncee", "Established", "Listening", "Closing" };
 
 void	ilrcvmsg(Ipconv*, Block*);
 void	ilackproc(void*);
@@ -186,7 +185,7 @@ ilrcvmsg(Ipconv *ipc, Block *bp)
 {
 	Ilhdr *ih;
 	int plen;
-	Ipconv *s, *etab;
+	Ipconv *s, *etab, *new;
 	short sp, dp;
 
 	ih = (Ilhdr *)bp;
@@ -210,13 +209,29 @@ ilrcvmsg(Ipconv *ipc, Block *bp)
 		}
 			
 	}
+
 	for(s = ipc; s < etab; s++) {
 		if(s->ilctl.state == Illistening && s->psrc == 0) {
 			/* Do the listener stuff */
-			ilprocess(s, ih, bp);
+			new = ipincoming(ipc);
+			if(new == 0) 
+				goto reset;
+			if(ih->type != Ilsync)
+				goto reset;
+
+			new->newcon = 1;
+			new->ipinterface = s->ipinterface;
+			s->ipinterface->ref++;
+			new->psrc = sp;
+			new->pdst = dp;
+			new->dst = nhgetl(ih->src);
+			ilprocess(new, ih, bp);
+
+			wakeup(&s->listenr);
 			return;
 		}
 	}
+reset:
 	ilsendctl(0, ih, Ilreset, 0);
 drop:
 	freeb(bp);
@@ -333,5 +348,4 @@ ilstart(Ipconv *ipc, int type, int window)
 		ilsendctl(ipc, 0, Ilsync, 1);
 		break;
 	}
-
 }
diff --git a/port/stip.c b/port/stip.c
index 1b7dedab466ac7d8407756ec4094962306bf7c3a..db51a48fadd36bb27db86299fb7196d3f175d75d 100644
--- a/port/stip.c
+++ b/port/stip.c
@@ -555,7 +555,6 @@ ip_csum(uchar *addr)
 
 	sum = (sum & 0xffff) + (sum >> 16);
 	sum = (sum & 0xffff) + (sum >> 16);
-
 	return (sum^0xffff);
 }
 
diff --git a/port/tcpinput.c b/port/tcpinput.c
index c8bdc2ca49319c4103c2f1610f8144af817cee31..99143d0a132215eaea5647ce81e3b2f04585628c 100644
--- a/port/tcpinput.c
+++ b/port/tcpinput.c
@@ -34,7 +34,7 @@ tcpinit(void)
 void
 tcp_input(Ipconv *ipc, Block *bp)
 {
-	Ipconv *s, *new, *etab;
+	Ipconv *s, *new;
 	Tcpctl *tcb;		
 	Tcphdr *h;
 	Tcp seg;
@@ -108,21 +108,8 @@ tcp_input(Ipconv *ipc, Block *bp)
 			goto clear;
 		}
 
-		/* Find a conversation to clone onto */
-		etab = &ipc[conf.ip];
-		for(new = ipc; new < etab; new++) {
-			if(new->ref == 0 && canqlock(new)) {
-				if(new->ref || new->tcpctl.state != CLOSED) {
-					qunlock(new);
-					continue;
-				}
-				new->ref++;
-				qunlock(new);
-				break;
-			}
-		}
-
-		if(new == etab)
+		new = ipincoming(ipc);
+		if(new == 0)
 			goto clear;
 
 		s->curlog++;
@@ -137,11 +124,11 @@ tcp_input(Ipconv *ipc, Block *bp)
 		new->tcpctl.acktimer.arg = new;
 		new->tcpctl.acktimer.state = TIMER_STOP;
 
+		new->newcon = 1;
 		new->ipinterface = s->ipinterface;
 		s->ipinterface->ref++;
-
-		/* Wake the sleeping dodo */
 		wakeup(&s->listenr);
+
 		s = new;
 	}