From 9d165d9f13f6e4f97fccd264ee769c999d95a226 Mon Sep 17 00:00:00 2001
From: Hartmut Brandt <harti@FreeBSD.org>
Date: Tue, 10 Jan 2006 11:59:31 +0000
Subject: [PATCH] Vendor fix: the routing table can change while we are
 fetching it from the kernel. Instead of complaining if we get an ENOMEM
 (meaning it got larger than our buffer is) reallocate the buffer and loop.

Submitted by: maxim
---
 contrib/bsnmp/snmp_mibII/mibII.c | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/contrib/bsnmp/snmp_mibII/mibII.c b/contrib/bsnmp/snmp_mibII/mibII.c
index 2f7881f92747..aa5cb8382709 100644
--- a/contrib/bsnmp/snmp_mibII/mibII.c
+++ b/contrib/bsnmp/snmp_mibII/mibII.c
@@ -1030,7 +1030,7 @@ u_char *
 mib_fetch_rtab(int af, int info, int arg, size_t *lenp)
 {
 	int name[6];
-	u_char *buf;
+	u_char *buf, *newbuf;
 
 	name[0] = CTL_NET;
 	name[1] = PF_ROUTE;
@@ -1041,6 +1041,7 @@ mib_fetch_rtab(int af, int info, int arg, size_t *lenp)
 
 	*lenp = 0;
 
+	/* initial estimate */
 	if (sysctl(name, 6, NULL, lenp, NULL, 0) == -1) {
 		syslog(LOG_ERR, "sysctl estimate (%d,%d,%d,%d,%d,%d): %m",
 		    name[0], name[1], name[2], name[3], name[4], name[5]);
@@ -1049,15 +1050,24 @@ mib_fetch_rtab(int af, int info, int arg, size_t *lenp)
 	if (*lenp == 0)
 		return (NULL);
 
-	if ((buf = malloc(*lenp)) == NULL) {
-		syslog(LOG_ERR, "sysctl buffer: %m");
-		return (NULL);
-	}
+	buf = NULL;
+	for (;;) {
+		if ((newbuf = realloc(buf, *lenp)) == NULL) {
+			syslog(LOG_ERR, "sysctl buffer: %m");
+			free(buf);
+			return (NULL);
+		}
+		buf = newbuf;
+			
+		if (sysctl(name, 6, buf, lenp, NULL, 0) == 0)
+			break;
 
-	if (sysctl(name, 6, buf, lenp, NULL, 0) == -1) {
-		syslog(LOG_ERR, "sysctl get: %m");
-		free(buf);
-		return (NULL);
+		if (errno != ENOMEM) {
+			syslog(LOG_ERR, "sysctl get: %m");
+			free(buf);
+			return (NULL);
+		}
+		*lenp += *lenp / 8 + 1;
 	}
 
 	return (buf);