From f64a30f1baf253b75432f1c465b2a1843b640a31 Mon Sep 17 00:00:00 2001
From: deraadt <deraadt@openbsd.org>
Date: Sun, 26 Nov 1995 23:40:17 +0000
Subject: [PATCH] add sysctl net.inet.ip.sourceroute option; default to 0.
 copied from freebsd

---
 sys/netinet/in.h       |  4 +++-
 sys/netinet/ip_input.c | 21 ++++++++++++++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/sys/netinet/in.h b/sys/netinet/in.h
index 0a784031333..deda496b68e 100644
--- a/sys/netinet/in.h
+++ b/sys/netinet/in.h
@@ -243,7 +243,8 @@ struct ip_mreq {
 #ifdef notyet
 #define	IPCTL_DEFMTU		4	/* default MTU */
 #endif
-#define	IPCTL_MAXID		5
+#define IPCTL_SOURCEROUTE	5	/* may perform source routes */
+#define	IPCTL_MAXID		6
 
 #define	IPCTL_NAMES { \
 	{ 0, 0 }, \
@@ -251,6 +252,7 @@ struct ip_mreq {
 	{ "redirect", CTLTYPE_INT }, \
 	{ "ttl", CTLTYPE_INT }, \
 	{ "mtu", CTLTYPE_INT }, \
+	{ "sourceroute", CTLTYPE_INT }, \
 }
 
 
diff --git a/sys/netinet/ip_input.c b/sys/netinet/ip_input.c
index 363254d2589..5fbc1d79265 100644
--- a/sys/netinet/ip_input.c
+++ b/sys/netinet/ip_input.c
@@ -45,6 +45,7 @@
 #include <sys/errno.h>
 #include <sys/time.h>
 #include <sys/kernel.h>
+#include <sys/syslog.h>
 
 #include <net/if.h>
 #include <net/route.h>
@@ -69,6 +70,7 @@
 #endif
 int	ipforwarding = IPFORWARDING;
 int	ipsendredirects = IPSENDREDIRECTS;
+int	ip_dosourceroute = 0;	/* no source routing unless sysctl'd to enable */
 int	ip_defttl = IPDEFTTL;
 #ifdef DIAGNOSTIC
 int	ipprintfs = 0;
@@ -702,6 +704,21 @@ ip_dooptions(m)
 				save_rte(cp, ip->ip_src);
 				break;
 			}
+
+			if (!ip_dosourceroute) {
+#if 0
+				char buf[4*sizeof "123"];
+				strcpy(buf, inet_ntoa(ip->ip_dst));
+
+				log(LOG_WARNING,
+				    "attempted source route from %s to %s\n",
+				    inet_ntoa(ip->ip_src), buf);
+#endif
+				type = ICMP_UNREACH;
+				code = ICMP_UNREACH_SRCFAIL;
+				goto bad;
+			}
+
 			/*
 			 * locate outgoing interface
 			 */
@@ -1069,7 +1086,7 @@ ip_forward(m, srcrt)
 		    code = ICMP_REDIRECT_HOST;
 #ifdef DIAGNOSTIC
 		    if (ipprintfs)
-		        printf("redirect (%d) to %lx\n", code, (u_int32_t)dest);
+			printf("redirect (%d) to %lx\n", code, (u_int32_t)dest);
 #endif
 		}
 	}
@@ -1151,6 +1168,8 @@ ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
 	case IPCTL_DEFMTU:
 		return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu));
 #endif
+	case IPCTL_SOURCEROUTE:
+		return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_dosourceroute));
 	default:
 		return (EOPNOTSUPP);
 	}
-- 
2.20.1