From 978935491a36c19e3c43436a3a0a89ddf5590277 Mon Sep 17 00:00:00 2001
From: benno <benno@openbsd.org>
Date: Sun, 11 Feb 2018 02:26:55 +0000
Subject: [PATCH] Add a ROUTE_PRIOFILTER socket option for roueing sockets that
 allows filtering on the priority of the route. All routes up to the specified
 value will be passed. ok claudio, ok henning previous version, feedback and
 manpage from sthen.

---
 share/man/man4/route.4 | 39 +++++++++++++++++++++++++++++++++++++--
 sys/net/route.h        |  5 ++++-
 sys/net/rtsock.c       | 22 ++++++++++++++++++++--
 3 files changed, 61 insertions(+), 5 deletions(-)

diff --git a/share/man/man4/route.4 b/share/man/man4/route.4
index 654b9a1505a..7051c421e54 100644
--- a/share/man/man4/route.4
+++ b/share/man/man4/route.4
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: route.4,v 1.44 2018/01/12 04:36:44 deraadt Exp $
+.\"	$OpenBSD: route.4,v 1.45 2018/02/11 02:26:55 benno Exp $
 .\"	$NetBSD: route.4,v 1.3 1994/11/30 16:22:31 jtc Exp $
 .\"
 .\" Copyright (c) 1990, 1991, 1993
@@ -30,7 +30,7 @@
 .\"
 .\"     @(#)route.4	8.6 (Berkeley) 4/19/94
 .\"
-.Dd $Mdocdate: January 12 2018 $
+.Dd $Mdocdate: February 11 2018 $
 .Dt ROUTE 4
 .Os
 .Sh NAME
@@ -210,6 +210,41 @@ if (setsockopt(routefd, PF_ROUTE, ROUTE_MSGFILTER,
 	err(1, "setsockopt(ROUTE_MSGFILTER)");
 .Ed
 .Pp
+Similarly, a process can specify that it is only interested in messages
+relating to routes where the priority is no more than a certain value
+by issuing a setsockopt call with the
+.Dv ROUTE_PRIOFILTER
+option.
+For example, to select only local, directly connected and static routes:
+.Bd -literal -offset indent
+unsigned int maxprio = RTP_STATIC;
+
+if (setsockopt(routefd, PF_ROUTE, ROUTE_PRIOFILTER,
+    &maxprio, sizeof(maxprio)) == -1)
+	err(1, "setsockopt(ROUTE_PRIOFILTER)");
+.Ed
+.Pp
+The predefined constants for the routing priorities are:
+.Bd -literal
+#define RTP_NONE	0	/* unset priority use sane default */
+#define RTP_LOCAL	1	/* local address routes (must be the highest) */
+#define RTP_CONNECTED	4	/* directly connected routes */
+#define RTP_STATIC	8	/* static routes base priority */
+#define RTP_EIGRP	28	/* EIGRP routes */
+#define RTP_OSPF	32	/* OSPF routes */
+#define RTP_ISIS	36	/* IS-IS routes */
+#define RTP_RIP		40	/* RIP routes */
+#define RTP_BGP		48	/* BGP routes */
+#define RTP_DEFAULT	56	/* routes that have nothing set */
+#define RTP_PROPOSAL_STATIC	57
+#define RTP_PROPOSAL_DHCLIENT	58
+#define RTP_PROPOSAL_SLAAC	59
+#define RTP_MAX		63	/* maximum priority */
+#define RTP_ANY		64	/* any of the above */
+#define RTP_MASK	0x7f
+#define RTP_DOWN	0x80	/* route/link is down */
+.Ed
+.Pp
 If a route is in use when it is deleted,
 the routing entry will be marked down and removed from the routing table,
 but the resources associated with it will not
diff --git a/sys/net/route.h b/sys/net/route.h
index 1ca0a22c45f..9f5459a9a62 100644
--- a/sys/net/route.h
+++ b/sys/net/route.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: route.h,v 1.167 2017/08/02 08:38:28 mpi Exp $	*/
+/*	$OpenBSD: route.h,v 1.168 2018/02/11 02:26:55 benno Exp $	*/
 /*	$NetBSD: route.h,v 1.9 1996/02/13 22:00:49 christos Exp $	*/
 
 /*
@@ -297,6 +297,9 @@ struct rt_msghdr {
 				   sent to the client. */
 #define ROUTE_TABLEFILTER 2	/* change routing table the socket is listening
 				   on, RTABLE_ANY listens on all tables. */
+#define ROUTE_PRIOFILTER 3	/* only pass updates with a priority higher or
+				   equal (actual value lower) to the specified
+				   priority. */
 
 #define ROUTE_FILTER(m)	(1 << (m))
 #define RTABLE_ANY	0xffffffff
diff --git a/sys/net/rtsock.c b/sys/net/rtsock.c
index 35bdd09d143..70497d29a93 100644
--- a/sys/net/rtsock.c
+++ b/sys/net/rtsock.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtsock.c,v 1.260 2018/02/08 22:24:41 claudio Exp $	*/
+/*	$OpenBSD: rtsock.c,v 1.261 2018/02/11 02:26:55 benno Exp $	*/
 /*	$NetBSD: rtsock.c,v 1.18 1996/03/29 00:32:10 cgd Exp $	*/
 
 /*
@@ -141,6 +141,7 @@ struct routecb {
 	unsigned int		msgfilter;
 	unsigned int		flags;
 	u_int			rtableid;
+	u_char			priority;
 };
 #define	sotoroutecb(so)	((struct routecb *)(so)->so_pcb)
 
@@ -308,7 +309,7 @@ route_ctloutput(int op, struct socket *so, int level, int optname,
 {
 	struct routecb *rop = sotoroutecb(so);
 	int error = 0;
-	unsigned int tid;
+	unsigned int tid, prio;
 
 	if (level != AF_ROUTE)
 		return (EINVAL);
@@ -333,6 +334,17 @@ route_ctloutput(int op, struct socket *so, int level, int optname,
 			else
 				rop->rtableid = tid;
 			break;
+		case ROUTE_PRIOFILTER:
+			if (m == NULL || m->m_len != sizeof(unsigned int)) {
+				error = EINVAL;
+				break;
+			}
+			prio = *mtod(m, unsigned int *);
+			if (prio > RTP_MAX)
+				error = EINVAL;
+			else
+				rop->priority = prio;
+			break;
 		default:
 			error = ENOPROTOOPT;
 			break;
@@ -348,6 +360,10 @@ route_ctloutput(int op, struct socket *so, int level, int optname,
 			m->m_len = sizeof(unsigned int);
 			*mtod(m, unsigned int *) = rop->rtableid;
 			break;
+		case ROUTE_PRIOFILTER:
+			m->m_len = sizeof(unsigned int);
+			*mtod(m, unsigned int *) = rop->priority;
+			break;
 		default:
 			error = ENOPROTOOPT;
 			break;
@@ -431,6 +447,8 @@ route_input(struct mbuf *m0, struct socket *so, sa_family_t sa_family)
 		if (rtm->rtm_type != RTM_DESYNC && rop->msgfilter != 0 &&
 		    !(rop->msgfilter & (1 << rtm->rtm_type)))
 			continue;
+		if (rop->priority != 0 && rop->priority < rtm->rtm_priority)
+			continue;
 		switch (rtm->rtm_type) {
 		case RTM_IFANNOUNCE:
 		case RTM_DESYNC:
-- 
2.20.1