- Add IPv6 over GRE.

- u_short -> u_int16_t
- Change default MTU to 1476 (same value that Cisco and other *BSD's use).
- Mark gre(4) interfaces as IFT_TUNNEL (Encapsulation interface).

From NetBSD

- Support setting the MTU

Be very careful when upgrading, the change in default MTU might cause
problems with an existing OpenBSD <-> OpenBSD setup.

Thanks to Stephen Marley <stephen dot marley at catwoman dot cl-is dot com>
for some testing.

2 files changed, 40 insertions, 16 deletions

diff --git a/sys/net/if_gre.c b/sys/net/if_gre.c
index fc20588a14c..f84091156a1 100644
--- a/sys/net/if_gre.c
+++ b/sys/net/if_gre.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: if_gre.c,v 1.32 2004/08/18 18:37:53 canacar Exp $ */
+/*      $OpenBSD: if_gre.c,v 1.33 2005/05/14 19:24:23 brad Exp $ */
 /*	$NetBSD: if_gre.c,v 1.9 1999/10/25 19:18:11 drochner Exp $ */
 
 /*
@@ -8,6 +8,8 @@
  * This code is derived from software contributed to The NetBSD Foundation
  * by Heiko W.Rupp <hwr@pilhuhn.de>
  *
+ * IPv6-over-GRE contributed by Gert Doering <gert@greenie.muc.de>
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ -93,11 +95,12 @@
 #define GRE_RECURSION_LIMIT	3   /* How many levels of recursion allowed */
 #endif /* GRE_RECURSION_LIMIT */
 
-#define GREMTU 1450	/* XXX this is below the standard MTU of
-                         1500 Bytes, allowing for headers,
-                         but we should possibly do path mtu discovery
-                         before changing if state to up to find the
-                         correct value */
+/*
+ * It is not easy to calculate the right value for a GRE MTU.
+ * We leave this task to the admin and use the same default that
+ * other vendors use.
+ */
+#define GREMTU 1476
 
 int	gre_clone_create(struct if_clone *, int);
 int	gre_clone_destroy(struct ifnet *);
@@ -141,7 +144,7 @@ gre_clone_create(struct if_clone *ifc, int unit)
 	snprintf(sc->sc_if.if_xname, sizeof sc->sc_if.if_xname, "%s%d",
 	    ifc->ifc_name, unit);
 	sc->sc_if.if_softc = sc;
-	sc->sc_if.if_type = IFT_OTHER;
+	sc->sc_if.if_type = IFT_TUNNEL;
 	sc->sc_if.if_addrlen = 0;
 	sc->sc_if.if_hdrlen = 24; /* IP + GRE */
 	sc->sc_if.if_mtu = GREMTU;
@@ -203,7 +206,8 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 	struct gre_softc *sc = (struct gre_softc *) (ifp->if_softc);
 	struct greip *gh = NULL;
 	struct ip *inp = NULL;
-	u_short etype = 0;
+	u_int8_t ip_tos = 0;
+	u_int16_t etype = 0;
 	struct mobile_h mob_h;
 	struct m_tag *mtag;
 
@@ -314,7 +318,7 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 			}
 
 			HTONS(mob_h.proto);
-			mob_h.hcrc = gre_in_cksum((u_short *) &mob_h, msiz);
+			mob_h.hcrc = gre_in_cksum((u_int16_t *) &mob_h, msiz);
 
 			/* Squeeze in the mobility header */
 			if ((m->m_data - msiz) < m->m_pktdat) {
@@ -377,6 +381,7 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 			}
 
 			inp = mtod(m, struct ip *);
+			ip_tos = inp->ip_tos;
 			etype = ETHERTYPE_IP;
 			break;
 #ifdef NETATALK
@@ -389,6 +394,11 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 			etype = ETHERTYPE_NS;
 			break;
 #endif
+#ifdef INET6
+		case AF_INET6:
+			etype = ETHERTYPE_IPV6;
+			break;
+#endif
 		default:
 			IF_DROP(&ifp->if_snd);
 			m_freem(m);
@@ -424,7 +434,7 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 		gh->gi_dst = sc->g_dst;
 		((struct ip *) gh)->ip_hl = (sizeof(struct ip)) >> 2;
 		((struct ip *) gh)->ip_ttl = ip_defttl;
-		((struct ip *) gh)->ip_tos = inp->ip_tos;
+		((struct ip *) gh)->ip_tos = ip_tos;
 		gh->gi_len = htons(m->m_pkthdr.len);
 	}
 
@@ -465,6 +475,16 @@ gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
 		else
 			sc->g_proto = IPPROTO_MOBILE;
 		break;
+	case SIOCSIFMTU:
+		if (ifr->ifr_mtu < 576) {
+			error = EINVAL;
+			break;
+		}
+		ifp->if_mtu = ifr->ifr_mtu;
+		break;
+	case SIOCGIFMTU:
+		ifr->ifr_mtu = sc->sc_if.if_mtu;
+		break;
 	case SIOCADDMULTI:
 	case SIOCDELMULTI:
 		if (ifr == 0) {
@@ -476,6 +496,10 @@ gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
 		case AF_INET:
 			break;
 #endif
+#ifdef INET6
+		case AF_INET6:
+			break;
+#endif
 		default:
 			error = EAFNOSUPPORT;
 			break;
@@ -665,10 +689,10 @@ gre_compute_route(struct gre_softc *sc)
  * do a checksum of a buffer - much like in_cksum, which operates on
  * mbufs.
  */
-u_short
-gre_in_cksum(u_short *p, u_int len)
+u_int16_t
+gre_in_cksum(u_int16_t *p, u_int len)
 {
-	u_int sum = 0;
+	u_int32_t sum = 0;
 	int nwords = len >> 1;
 
 	while (nwords-- != 0)
diff --git a/sys/net/if_gre.h b/sys/net/if_gre.h
index ed7fcbb67ca..d42429abaf0 100644
--- a/sys/net/if_gre.h
+++ b/sys/net/if_gre.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: if_gre.h,v 1.9 2003/12/03 14:52:23 markus Exp $ */
+/*      $OpenBSD: if_gre.h,v 1.10 2005/05/14 19:24:23 brad Exp $ */
 /*	$NetBSD: if_gre.h,v 1.5 1999/11/19 20:41:19 thorpej Exp $ */
 
 /*
@@ -147,7 +147,7 @@ extern  int ip_mobile_allow;
 void	greattach(int);
 int     gre_ioctl(struct ifnet *, u_long, caddr_t);
 int     gre_output(struct ifnet *, struct mbuf *, struct sockaddr *,
-	    struct rtentry *rt);
-u_short	gre_in_cksum(u_short *p, u_int len);
+	    struct rtentry *);
+u_int16_t gre_in_cksum(u_int16_t *, u_int);
 #endif /* _KERNEL */
 #endif /* _NET_IF_GRE_H_ */