Revert "Revert 295285 which was an MFC of the tryforward work (r290383,295282,295283)"

We are keeping tryforward enabled on pfSense since we do not use IPFW +
NAT

This reverts commit b899cad3faf3673f41a3fcf021164dcd7ee19a7e.

1 files changed, 5 insertions, 112 deletions

diff --git a/sys/netinet/ip_fastfwd.c b/sys/netinet/ip_fastfwd.c
index 3db6311..9c3ea66 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;