MFC: r290383,295282,295283

Replace the fastforward path with tryforward which does not require a
sysctl and will always be on. The former split between default and
fast forwarding is removed by this commit while preserving the ability
to use all network stack features.

Differential Revision:	https://reviews.freebsd.org/D4042
Reviewed by:	ae, melifaro, olivier, rwatson
Approved by:	re (glebius)
Sponsored by:	Rubicon Communications (Netgate)

1 files changed, 5 insertions, 112 deletions

diff --git a/sys/netinet/ip_fastfwd.c b/sys/netinet/ip_fastfwd.c
index 0772cf0..13c5785 100644
--- a/sys/netinet/ip_fastfwd.c
+++ b/sys/netinet/ip_fastfwd.c
@@ -109,12 +109,6 @@ __FBSDID("$FreeBSD$");
 
 #include <machine/in_cksum.h>
 
-static VNET_DEFINE(int, ipfastforward_active);
-#define	V_ipfastforward_active		VNET(ipfastforward_active)
-
-SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, fastforwarding, CTLFLAG_RW,
-    &VNET_NAME(ipfastforward_active), 0, "Enable fast IP forwarding");
-
 static struct sockaddr_in *
 ip_findroute(struct route *ro, struct in_addr dest, struct mbuf *m)
 {
@@ -159,7 +153,7 @@ ip_findroute(struct route *ro, struct in_addr dest, struct mbuf *m)
  * to ip_input for full processing.
  */
 struct mbuf *
-ip_fastforward(struct mbuf *m)
+ip_tryforward(struct mbuf *m)
 {
 	struct ip *ip;
 	struct mbuf *m0 = NULL;
@@ -167,119 +161,20 @@ ip_fastforward(struct mbuf *m)
 	struct sockaddr_in *dst = NULL;
 	struct ifnet *ifp;
 	struct in_addr odest, dest;
-	uint16_t sum, ip_len, ip_off;
+	uint16_t ip_len, ip_off;
 	int error = 0;
-	int hlen, mtu;
+	int mtu;
 	struct m_tag *fwd_tag = NULL;
 
 	/*
 	 * Are we active and forwarding packets?
 	 */
-	if (!V_ipfastforward_active || !V_ipforwarding)
-		return m;
 
 	M_ASSERTVALID(m);
 	M_ASSERTPKTHDR(m);
 
 	bzero(&ro, sizeof(ro));
 
-	/*
-	 * Step 1: check for packet drop conditions (and sanity checks)
-	 */
-
-	/*
-	 * Is entire packet big enough?
-	 */
-	if (m->m_pkthdr.len < sizeof(struct ip)) {
-		IPSTAT_INC(ips_tooshort);
-		goto drop;
-	}
-
-	/*
-	 * Is first mbuf large enough for ip header and is header present?
-	 */
-	if (m->m_len < sizeof (struct ip) &&
-	   (m = m_pullup(m, sizeof (struct ip))) == NULL) {
-		IPSTAT_INC(ips_toosmall);
-		return NULL;	/* mbuf already free'd */
-	}
-
-	ip = mtod(m, struct ip *);
-
-	/*
-	 * Is it IPv4?
-	 */
-	if (ip->ip_v != IPVERSION) {
-		IPSTAT_INC(ips_badvers);
-		goto drop;
-	}
-
-	/*
-	 * Is IP header length correct and is it in first mbuf?
-	 */
-	hlen = ip->ip_hl << 2;
-	if (hlen < sizeof(struct ip)) {	/* minimum header length */
-		IPSTAT_INC(ips_badhlen);
-		goto drop;
-	}
-	if (hlen > m->m_len) {
-		if ((m = m_pullup(m, hlen)) == NULL) {
-			IPSTAT_INC(ips_badhlen);
-			return NULL;	/* mbuf already free'd */
-		}
-		ip = mtod(m, struct ip *);
-	}
-
-	/*
-	 * Checksum correct?
-	 */
-	if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED)
-		sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
-	else {
-		if (hlen == sizeof(struct ip))
-			sum = in_cksum_hdr(ip);
-		else
-			sum = in_cksum(m, hlen);
-	}
-	if (sum) {
-		IPSTAT_INC(ips_badsum);
-		goto drop;
-	}
-
-	/*
-	 * Remember that we have checked the IP header and found it valid.
-	 */
-	m->m_pkthdr.csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
-
-	ip_len = ntohs(ip->ip_len);
-
-	/*
-	 * Is IP length longer than packet we have got?
-	 */
-	if (m->m_pkthdr.len < ip_len) {
-		IPSTAT_INC(ips_tooshort);
-		goto drop;
-	}
-
-	/*
-	 * Is packet longer than IP header tells us? If yes, truncate packet.
-	 */
-	if (m->m_pkthdr.len > ip_len) {
-		if (m->m_len == m->m_pkthdr.len) {
-			m->m_len = ip_len;
-			m->m_pkthdr.len = ip_len;
-		} else
-			m_adj(m, ip_len - m->m_pkthdr.len);
-	}
-
-	/*
-	 * Is packet from or to 127/8?
-	 */
-	if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
-	    (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
-		IPSTAT_INC(ips_badaddr);
-		goto drop;
-	}
 
 #ifdef ALTQ
 	/*
@@ -290,12 +185,10 @@ ip_fastforward(struct mbuf *m)
 #endif
 
 	/*
-	 * Step 2: fallback conditions to normal ip_input path processing
-	 */
-
-	/*
 	 * Only IP packets without options
 	 */
+	ip = mtod(m, struct ip *);
+
 	if (ip->ip_hl != (sizeof(struct ip) >> 2)) {
 		if (V_ip_doopts == 1)
 			return m;