From 05e2df41cafcb95cf73b24d9cbc448349071bed2 Mon Sep 17 00:00:00 2001
From: Poul-Henning Kamp <phk@FreeBSD.org>
Date: Sun, 30 Aug 1992 00:00:00 +0000
Subject: [PATCH] CLEAN UP SLIP INTERFACE TO KEEP FROM HANGING

Here is a patch to clean up the interface between the tty-drivers, in
particular the com driver, and the sl# interfaces, this is not a work-around
but a genuine bug-fix.

Symptoms: after a number of "com#: silo overflow" SLIP ceases to work.

Overview of the problem:  the slip interface will disregard any notice
from the tty-driver on problems (parity errors, framing errors or overruns),
which basicly means the one might as well throw the packet away right away.
Also overrun in the packetizing will go relatively unnotized.

AUTHOR:         Poul-Henning Kamp (phk@data.fls.dk)
386BSD-Patchkit: patch00019
---
 usr/src/sys.386bsd/i386/isa/com.c |  7 +++++--
 usr/src/sys.386bsd/net/if_sl.c    | 17 ++++++++++++++++-
 usr/src/sys.386bsd/net/if_slvar.h |  8 ++++++++
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/usr/src/sys.386bsd/i386/isa/com.c b/usr/src/sys.386bsd/i386/isa/com.c
index 5b1c5fd53f..b370f30488 100644
--- a/usr/src/sys.386bsd/i386/isa/com.c
+++ b/usr/src/sys.386bsd/i386/isa/com.c
@@ -34,9 +34,10 @@
  *
  * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
  * --------------------         -----   ----------------------
- * CURRENT PATCH LEVEL:         1       00018
+ * CURRENT PATCH LEVEL:         2       00019
  * --------------------         -----   ----------------------
  *
+ * 30 Aug 92	Poul-Henning Kamp	Stabilize SLIP on lossy lines/UARTS
  * 09 Aug 92	Christoph Robitschko	Correct minor number on com ports
  */
 static char rcsid[] = "$Header: /usr/bill/working/sys/i386/isa/RCS/com.c,v 1.2 92/01/21 14:34:11 william Exp $";
@@ -375,8 +376,10 @@ comeint(unit, stat, com)
 		c |= TTY_FE;
 	else if (stat & LSR_PE)
 		c |= TTY_PE;
-	else if (stat & LSR_OE)
+	else if (stat & LSR_OE) {			/* 30 Aug 92*/
+		c |= TTY_PE;	/* Ought to have it's own define... */
 		log(LOG_WARNING, "com%d: silo overflow\n", unit);
+	}
 	(*linesw[tp->t_line].l_rint)(c, tp);
 }
 
diff --git a/usr/src/sys.386bsd/net/if_sl.c b/usr/src/sys.386bsd/net/if_sl.c
index 733c7b27e8..7e97e07f07 100644
--- a/usr/src/sys.386bsd/net/if_sl.c
+++ b/usr/src/sys.386bsd/net/if_sl.c
@@ -31,6 +31,13 @@
  * SUCH DAMAGE.
  *
  *	@(#)if_sl.c	7.22 (Berkeley) 4/20/91
+ *
+ * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
+ * --------------------         -----   ----------------------
+ * CURRENT PATCH LEVEL:         1       00019
+ * --------------------         -----   ----------------------
+ *
+ * 30 Aug 92    Poul-Henning Kamp       Stabilize SLIP on lossy lines/UARTS
  */
 
 /*
@@ -623,8 +630,10 @@ slinput(c, tp)
 	sc = (struct sl_softc *)tp->t_sc;
 	if (sc == NULL)
 		return;
-	if (!(tp->t_state&TS_CARR_ON))	/* XXX */
+	if (c > 255 || !(tp->t_state&TS_CARR_ON)) {       /* XXX 30 Aug 92*/
+		sc->sc_flags |= SC_ERROR;
 		return;
+	}
 
 	++sc->sc_bytesrcvd;
 	++sc->sc_if.if_ibytes;
@@ -674,7 +683,12 @@ slinput(c, tp)
 		return;
 
 	case FRAME_END:
+		if(sc->sc_flags & SC_ERROR) {			/* 30 Aug 92*/
+			sc->sc_flags &= ~SC_ERROR;
+			goto newpack;
+		}
 		len = sc->sc_mp - sc->sc_buf;
+
 		if (len < 3)
 			/* less than min length packet - ignore */
 			goto newpack;
@@ -730,6 +744,7 @@ slinput(c, tp)
 		sc->sc_escape = 0;
 		return;
 	}
+	sc->sc_flags |= SC_ERROR;			/* 30 Aug 92*/
 error:
 	sc->sc_if.if_ierrors++;
 newpack:
diff --git a/usr/src/sys.386bsd/net/if_slvar.h b/usr/src/sys.386bsd/net/if_slvar.h
index 076c0518f4..8fc81937bf 100644
--- a/usr/src/sys.386bsd/net/if_slvar.h
+++ b/usr/src/sys.386bsd/net/if_slvar.h
@@ -33,6 +33,13 @@
  *	@(#)if_slvar.h	7.7 (Berkeley) 5/7/91
  *
  * $Header: if_slvar.h,v 1.3 89/05/31 02:25:18 van Exp $
+ *
+ * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
+ * --------------------         -----   ----------------------
+ * CURRENT PATCH LEVEL:         1       00019
+ * --------------------         -----   ----------------------
+ *
+ * 30 Aug 92    Poul-Henning Kamp       Stabilize SLIP on lossy lines/UARTS
  */
 
 /*
@@ -65,6 +72,7 @@ struct sl_softc {
 #define	SC_NOICMP	0x0004		/* supress ICMP traffic */
 #define	SC_AUTOCOMP	0x0008		/* auto-enable TCP compression */
 /* internal flags (should be separate) */
+#define	SC_ERROR	0x08000		/* had an input error - 30 Aug 92*/
 #define	SC_ABORT	0x10000		/* have been sent an abort request */
 
 /* this stuff doesn't belong here... */
-- 
2.20.1