use mpls_ip_adjttl and mpls_ip6_adjttl in mpe instead of rolling it again.

mpls_ip_adjttl now patches the checksum rather than check it and
calculate it again. both mpls_ip_adjttl and mpls_ip6_adjttl now
rely on the caller to check the sysctls for whether they should run
or not, which paves the way for making it configurable in mpe via
the tunnel ioctls.

3 files changed, 47 insertions, 72 deletions

diff --git a/sys/net/if_mpe.c b/sys/net/if_mpe.c
index 1e556d96401..826cbdb1530 100644
--- a/sys/net/if_mpe.c
+++ b/sys/net/if_mpe.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: if_mpe.c,v 1.69 2019/01/27 04:54:06 dlg Exp $ */
+/* $OpenBSD: if_mpe.c,v 1.70 2019/01/27 05:13:04 dlg Exp $ */
 
 /*
  * Copyright (c) 2008 Pierre-Yves Ritschard <pyr@spootnik.org>
@@ -408,22 +408,9 @@ mpe_input(struct ifnet *ifp, struct mbuf *m)
 	switch (*mtod(n, uint8_t *) >> 4) {
 	case 4:
 		if (mpls_mapttl_ip) {
-			struct ip *ip;
-			uint16_t old, new, x;
-
-			if (m->m_len < sizeof(*ip)) {
-				m = m_pullup(m, sizeof(*ip));
-				if (m == NULL)
-					return;
-			}
-			ip = mtod(m, struct ip *);
-
-			old = htons(ip->ip_ttl << 8);
-			new = htons(ttl << 8);
-			x = ip->ip_sum + old - new;
-
-			ip->ip_ttl = ttl;
-			ip->ip_sum = (x) + (x >> 16);
+			m = mpls_ip_adjttl(m, ttl);
+			if (m == NULL)
+				return;
 		}
 		input = ipv4_input;
 		m->m_pkthdr.ph_family = AF_INET;
@@ -431,15 +418,9 @@ mpe_input(struct ifnet *ifp, struct mbuf *m)
 #ifdef INET6
 	case 6:
 		if (mpls_mapttl_ip6) {
-			struct ip6_hdr *ip6;
-
-			if (m->m_len < sizeof(*ip6)) {
-				m = m_pullup(m, sizeof(*ip6));
-				if (m == NULL)
-					return;
-			}
-			ip6 = mtod(m, struct ip6_hdr *);
-			ip6->ip6_hlim = ttl;
+			m = mpls_ip6_adjttl(m, ttl);
+			if (m == NULL)
+				return;
 		}
 		input = ipv6_input;
 		m->m_pkthdr.ph_family = AF_INET6;
diff --git a/sys/netmpls/mpls.h b/sys/netmpls/mpls.h
index bc6ee28196a..80116558739 100644
--- a/sys/netmpls/mpls.h
+++ b/sys/netmpls/mpls.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mpls.h,v 1.40 2019/01/27 04:20:59 dlg Exp $	*/
+/*	$OpenBSD: mpls.h,v 1.41 2019/01/27 05:13:04 dlg Exp $	*/
 
 /*
  * Copyright (C) 1999, 2000 and 2001 AYAME Project, WIDE Project.
@@ -155,7 +155,6 @@ struct ifmpwreq {
 
 extern	struct domain mplsdomain;
 
-
 extern int		mpls_defttl;
 extern int		mpls_mapttl_ip;
 extern int		mpls_mapttl_ip6;
@@ -166,6 +165,11 @@ struct mbuf	*mpls_shim_pop(struct mbuf *);
 struct mbuf	*mpls_shim_swap(struct mbuf *, struct rt_mpls *);
 struct mbuf	*mpls_shim_push(struct mbuf *, struct rt_mpls *);
 
+struct mbuf	*mpls_ip_adjttl(struct mbuf *, u_int8_t);
+#ifdef INET6
+struct mbuf	*mpls_ip6_adjttl(struct mbuf *, u_int8_t);
+#endif
+
 int		 mpls_output(struct ifnet *, struct mbuf *, struct sockaddr *,
 		    struct rtentry *);
 void		 mpls_input(struct ifnet *, struct mbuf *);
diff --git a/sys/netmpls/mpls_input.c b/sys/netmpls/mpls_input.c
index 57355e287cb..093d662246e 100644
--- a/sys/netmpls/mpls_input.c
+++ b/sys/netmpls/mpls_input.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mpls_input.c,v 1.72 2019/01/27 04:20:59 dlg Exp $	*/
+/*	$OpenBSD: mpls_input.c,v 1.73 2019/01/27 05:13:04 dlg Exp $	*/
 
 /*
  * Copyright (c) 2008 Claudio Jeker <claudio@openbsd.org>
@@ -45,11 +45,6 @@
 #define MPLS_TTL_GET(l)		(ntohl((l) & MPLS_TTL_MASK))
 #endif
 
-struct mbuf	*mpls_ip_adjttl(struct mbuf *, u_int8_t);
-#ifdef INET6
-struct mbuf	*mpls_ip6_adjttl(struct mbuf *, u_int8_t);
-#endif
-
 struct mbuf	*mpls_do_error(struct mbuf *, int, int, int);
 void		 mpls_input_local(struct rtentry *, struct mbuf *);
 
@@ -128,15 +123,21 @@ mpls_input(struct ifnet *ifp, struct mbuf *m)
 			switch (ntohl(smpls->smpls_label)) {
 			case MPLS_LABEL_IPV4NULL:
 do_v4:
-				if ((m = mpls_ip_adjttl(m, ttl)) == NULL)
-					return;
+				if (mpls_mapttl_ip) {
+					m = mpls_ip_adjttl(m, ttl);
+					if (m == NULL)
+						return;
+				}
 				ipv4_input(ifp, m);
 				return;
 #ifdef INET6
 			case MPLS_LABEL_IPV6NULL:
 do_v6:
-				if ((m = mpls_ip6_adjttl(m, ttl)) == NULL)
-					return;
+				if (mpls_mapttl_ip6) {
+					m = mpls_ip6_adjttl(m, ttl);
+					if (m == NULL)
+						return;
+				}
 				ipv6_input(ifp, m);
 				return;
 #endif	/* INET6 */
@@ -302,52 +303,41 @@ struct mbuf *
 mpls_ip_adjttl(struct mbuf *m, u_int8_t ttl)
 {
 	struct ip *ip;
-	int hlen;
+	uint16_t old, new, x;
 
-	if (mpls_mapttl_ip) {
-		if (m->m_len < sizeof(struct ip) &&
-		    (m = m_pullup(m, sizeof(struct ip))) == NULL)
-			return NULL;
-		ip = mtod(m, struct ip *);
-		hlen = ip->ip_hl << 2;
-		if (m->m_len < hlen) {
-			if ((m = m_pullup(m, hlen)) == NULL)
-				return NULL;
-			ip = mtod(m, struct ip *);
-		}
-		/* make sure we have a valid header */
-		if (in_cksum(m, hlen) != 0) {
-			m_freem(m);
-			return NULL;
-		}
+	if (m->m_len < sizeof(*ip)) {
+		m = m_pullup(m, sizeof(*ip));
+		if (m == NULL)
+			return (NULL);
+	}
+	ip = mtod(m, struct ip *);
 
-		/* set IP ttl from MPLS ttl */
-		ip->ip_ttl = ttl;
+	old = htons(ip->ip_ttl << 8);
+	new = htons(ttl << 8);
+	x = ip->ip_sum + old - new;
 
-		/* recalculate checksum */
-		ip->ip_sum = 0;
-		ip->ip_sum = in_cksum(m, hlen);
-	}
-	return m;
+	ip->ip_ttl = ttl;
+	ip->ip_sum = (x) + (x >> 16);
+
+	return (m);
 }
 
 #ifdef INET6
 struct mbuf *
 mpls_ip6_adjttl(struct mbuf *m, u_int8_t ttl)
 {
-	struct ip6_hdr *ip6hdr;
+	struct ip6_hdr *ip6;
 
-	if (mpls_mapttl_ip6) {
-		if (m->m_len < sizeof(struct ip6_hdr) &&
-		    (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL)
-			return NULL;
+	if (m->m_len < sizeof(*ip6)) {
+		m = m_pullup(m, sizeof(*ip6));
+		if (m == NULL)
+			return (NULL);
+	}
+	ip6 = mtod(m, struct ip6_hdr *);
 
-		ip6hdr = mtod(m, struct ip6_hdr *);
+	ip6->ip6_hlim = ttl;
 
-		/* set IPv6 ttl from MPLS ttl */
-		ip6hdr->ip6_hlim = ttl;
-	}
-	return m;
+	return (m);
 }
 #endif	/* INET6 */