From cdb877c33d6cc233b12f3f889f372a15d70559e4 Mon Sep 17 00:00:00 2001
From: Garrett Wollman <wollman@FreeBSD.org>
Date: Mon, 6 Jan 1997 17:24:50 +0000
Subject: [PATCH] Quoth Vern:

ftp.sgi.com:sgi/src/routed.tar.Z has a fix that has been cooking for a week
or so and that fixes a problem in the new hash tables for zillions of
interface aliases.  The bug was that interfaces that come and go, such
as for SLIP and PPP, would get permanently lost.

Submitted by:	Vernon J. Schryver <vjs@mica.denver.sgi.com>
---
 sbin/routed/if.c    | 47 +++++++++++++++++++++++----------------------
 sbin/routed/input.c |  2 +-
 2 files changed, 25 insertions(+), 24 deletions(-)

diff --git a/sbin/routed/if.c b/sbin/routed/if.c
index 860c07537ac7..b68ff52a9134 100644
--- a/sbin/routed/if.c
+++ b/sbin/routed/if.c
@@ -36,7 +36,7 @@ static char sccsid[] = "@(#)if.c	8.1 (Berkeley) 6/5/93";
 #elif defined(__NetBSD__)
 static char rcsid[] = "$NetBSD$";
 #endif
-#ident "$Revision: 1.22 $"
+#ident "$Revision: 1.23 $"
 
 #include "defs.h"
 #include "pathnames.h"
@@ -49,12 +49,12 @@ struct interface *ifnet;		/* all interfaces */
  * by name or address.
  */
 #define AHASH_LEN 211			/* must be prime */
-#define AHASH(a) &ahash[(a)%AHASH_LEN]
-struct interface *ahash[AHASH_LEN];
+#define AHASH(a) &ahash_tbl[(a)%AHASH_LEN]
+struct interface *ahash_tbl[AHASH_LEN];
 
 #define BHASH_LEN 211			/* must be prime */
-#define BHASH(a) &bhash[(a)%BHASH_LEN]
-struct interface *bhash[BHASH_LEN];
+#define BHASH(a) &bhash_tbl[(a)%BHASH_LEN]
+struct interface *bhash_tbl[BHASH_LEN];
 
 struct interface *remote_if;		/* remote interfaces */
 
@@ -63,7 +63,7 @@ struct interface *remote_if;		/* remote interfaces */
  * aliases are put on the end of the hash chains.
  */
 #define NHASH_LEN 97
-struct interface *nhash[NHASH_LEN];
+struct interface *nhash_tbl[NHASH_LEN];
 
 int	tot_interfaces;			/* # of remote and local interfaces */
 int	rip_interfaces;			/* # of interfaces doing RIP */
@@ -77,13 +77,24 @@ int	have_ripv1_out;			/* have a RIPv1 interface */
 int	have_ripv1_in;
 
 
+static struct interface**
+nhash(register char *p)
+{
+	register u_int i;
+
+	for (i = 0; *p != '\0'; p++) {
+		i = ((i<<1) & 0x7fffffff) | ((i>>31) & 1);
+		i ^= *p;
+	}
+	return &nhash_tbl[i % NHASH_LEN];
+}
+
+
 /* Link a new interface into the lists and hash tables.
  */
 void
 if_link(struct interface *ifp)
 {
-	int i;
-	char *p;
 	struct interface **hifp;
 
 	ifp->int_prev = &ifnet;
@@ -94,14 +105,12 @@ if_link(struct interface *ifp)
 
 	hifp = AHASH(ifp->int_addr);
 	ifp->int_ahash_prev = hifp;
-	ifp->int_ahash = *hifp;
 	if ((ifp->int_ahash = *hifp) != 0)
 		(*hifp)->int_ahash_prev = &ifp->int_ahash;
 	*hifp = ifp;
 
 	if (ifp->int_if_flags & IFF_BROADCAST) {
 		hifp = BHASH(ifp->int_brdaddr);
-		ifp->int_bhash = *hifp;
 		ifp->int_bhash_prev = hifp;
 		if ((ifp->int_bhash = *hifp) != 0)
 			(*hifp)->int_bhash_prev = &ifp->int_bhash;
@@ -116,15 +125,12 @@ if_link(struct interface *ifp)
 		remote_if = ifp;
 	}
 
-	for (i = 0, p = ifp->int_name; *p != '\0'; p++)
-		i += *p;
-	hifp = &nhash[i % NHASH_LEN];
+	hifp = nhash(ifp->int_name);
 	if (ifp->int_state & IS_ALIAS) {
 		/* put aliases on the end of the hash chain */
 		while (*hifp != 0)
 			hifp = &(*hifp)->int_nhash;
 	}
-	ifp->int_nhash = *hifp;
 	ifp->int_nhash_prev = hifp;
 	if ((ifp->int_nhash = *hifp) != 0)
 		(*hifp)->int_nhash_prev = &ifp->int_nhash;
@@ -177,15 +183,9 @@ ifwithname(char *name,			/* "ec0" or whatever */
 	   naddr addr)			/* 0 or network address */
 {
 	struct interface *ifp;
-	int i;
-	char *p;
 
 	for (;;) {
-		for (i = 0, p = name; *p != '\0'; p++)
-			i += *p;
-		ifp = nhash[i % NHASH_LEN];
-
-		while (ifp != 0) {
+		for (ifp = *nhash(name); ifp != 0; ifp = ifp->int_nhash) {
 			/* If the network address is not specified,
 			 * ignore any alias interfaces.  Otherwise, look
 			 * for the interface with the target name and address.
@@ -194,10 +194,8 @@ ifwithname(char *name,			/* "ec0" or whatever */
 			    && ((addr == 0 && !(ifp->int_state & IS_ALIAS))
 				|| (ifp->int_addr == addr)))
 				return ifp;
-			ifp = ifp->int_nhash;
 		}
 
-
 		/* If there is no known interface, maybe there is a
 		 * new interface.  So just once look for new interfaces.
 		 */
@@ -445,6 +443,9 @@ ifdel(struct interface *ifp)
 	*ifp->int_ahash_prev = ifp->int_ahash;
 	if (ifp->int_ahash != 0)
 		ifp->int_ahash->int_ahash_prev = ifp->int_ahash_prev;
+	*ifp->int_nhash_prev = ifp->int_nhash;
+	if (ifp->int_nhash != 0)
+		ifp->int_nhash->int_nhash_prev = ifp->int_nhash_prev;
 	if (ifp->int_if_flags & IFF_BROADCAST) {
 		*ifp->int_bhash_prev = ifp->int_bhash;
 		if (ifp->int_bhash != 0)
diff --git a/sbin/routed/input.c b/sbin/routed/input.c
index cfc680db8065..0e2c16fd7414 100644
--- a/sbin/routed/input.c
+++ b/sbin/routed/input.c
@@ -36,7 +36,7 @@ static char sccsid[] = "@(#)input.c	8.1 (Berkeley) 6/5/93";
 #elif defined(__NetBSD__)
 static char rcsid[] = "$NetBSD$";
 #endif
-#ident "$Revision: 1.20 $"
+#ident "$Revision: 1.21 $"
 
 #include "defs.h"