Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

===================================================================
RCS file: /ftp/cvs/cvsroot/src/sys/netinet/ip_input.c,v
rcsdiff: /ftp/cvs/cvsroot/src/sys/netinet/ip_input.c,v: warning: Unknown phrases like `commitid ...;' are present.
retrieving revision 1.203
retrieving revision 1.211
diff -u -p -r1.203 -r1.211
--- src/sys/netinet/ip_input.c	2004/05/25 04:34:00	1.203
+++ src/sys/netinet/ip_input.c	2005/02/03 22:56:42	1.211
@@ -1,4 +1,4 @@
-/*	$NetBSD: ip_input.c,v 1.203 2004/05/25 04:34:00 atatat Exp $	*/
+/*	$NetBSD: ip_input.c,v 1.211 2005/02/03 22:56:42 perry Exp $	*/
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -98,7 +98,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ip_input.c,v 1.203 2004/05/25 04:34:00 atatat Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ip_input.c,v 1.211 2005/02/03 22:56:42 perry Exp $");
 
 #include "opt_inet.h"
 #include "opt_gateway.h"
@@ -200,6 +200,7 @@ int	ipprintfs = 0;
 #endif
 
 int	ip_do_randomid = 0;
+int	ip_do_loopback_cksum = 0;
 
 /*
  * XXX - Setting ip_checkinterface mostly implements the receive side of
@@ -240,7 +241,7 @@ struct pfil_head inet_pfil_hook;
  * recalculate IP parameters derived from nmbclusters.
  */
 static int	ip_nmbclusters;			/* copy of nmbclusters */
-static void	ip_nmbclusters_changed __P((void));	/* recalc limits */
+static void	ip_nmbclusters_changed(void);	/* recalc limits */
 
 #define CHECK_NMBCLUSTER_PARAMS()				\
 do {								\
@@ -274,15 +275,15 @@ int	ip_maxfrags;		        /* limit on fr
  * repeatedly deleting single packets under heavy fragmentation load
  * (e.g., from lossy NFS peers).
  */
-static u_int	ip_reass_ttl_decr __P((u_int ticks)); 
-static void	ip_reass_drophalf __P((void));
+static u_int	ip_reass_ttl_decr(u_int ticks); 
+static void	ip_reass_drophalf(void);
 
 
-static __inline int ipq_lock_try __P((void));
-static __inline void ipq_unlock __P((void));
+static __inline int ipq_lock_try(void);
+static __inline void ipq_unlock(void);
 
 static __inline int
-ipq_lock_try()
+ipq_lock_try(void)
 {
 	int s;
 
@@ -301,7 +302,7 @@ ipq_lock_try()
 }
 
 static __inline void
-ipq_unlock()
+ipq_unlock(void)
 {
 	int s;
 
@@ -372,7 +373,7 @@ static	struct ip_srcrt {
 	struct	in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
 } ip_srcrt;
 
-static void save_rte __P((u_char *, struct in_addr));
+static void save_rte(u_char *, struct in_addr);
 
 #ifdef MBUFTRACE
 struct mowner ip_rx_mowner = { "internet", "rx" };
@@ -394,7 +395,7 @@ ip_nmbclusters_changed(void)
  * All protocols not implemented in kernel go to raw IP protocol handler.
  */
 void
-ip_init()
+ip_init(void)
 {
 	const struct protosw *pr;
 	int i;
@@ -451,7 +452,7 @@ struct	route ipforward_rt;
  * IP software interrupt routine
  */
 void
-ipintr()
+ipintr(void)
 {
 	int s;
 	struct mbuf *m;
@@ -572,10 +573,16 @@ ip_input(struct mbuf *m)
 		break;
 
 	default:
-		/* Must compute it ourselves. */
-		INET_CSUM_COUNTER_INCR(&ip_swcsum);
-		if (in_cksum(m, hlen) != 0)
-			goto bad;
+		/*
+		 * Must compute it ourselves.  Maybe skip checksum on
+		 * loopback interfaces.
+		 */
+		if (__predict_true(!(m->m_pkthdr.rcvif->if_flags &
+				     IFF_LOOPBACK) || ip_do_loopback_cksum)) {
+			INET_CSUM_COUNTER_INCR(&ip_swcsum);
+			if (in_cksum(m, hlen) != 0)
+				goto badcsum;
+		}
 		break;
 	}
 
@@ -649,6 +656,20 @@ ip_input(struct mbuf *m)
 			return;
 		ip = mtod(m, struct ip *);
 		hlen = ip->ip_hl << 2;
+		/*
+		 * XXX The setting of "srcrt" here is to prevent ip_forward()
+		 * from generating ICMP redirects for packets that have
+		 * been redirected by a hook back out on to the same LAN that
+		 * they came from and is not an indication that the packet
+		 * is being inffluenced by source routing options.  This
+		 * allows things like
+		 * "rdr tlp0 0/0 port 80 -> 1.1.1.200 3128 tcp"
+		 * where tlp0 is both on the 1.1.1.0/24 network and is the
+		 * default route for hosts on 1.1.1.0/24.  Of course this
+		 * also requires a "map tlp0 ..." to complete the story.
+		 * One might argue whether or not this kind of network config.
+		 * should be supported in this manner... 
+		 */
 		srcrt = (odst.s_addr != ip->ip_dst.s_addr);
 	}
 #endif /* PFIL_HOOKS */
@@ -712,7 +733,7 @@ ip_input(struct mbuf *m)
 	if (ia != NULL)
 		goto ours;
 	if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
-		TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrlist, ifa_list) {
+		IFADDR_FOREACH(ifa, m->m_pkthdr.rcvif) {
 			if (ifa->ifa_addr->sa_family != AF_INET)
 				continue;
 			ia = ifatoia(ifa);
@@ -1023,10 +1044,7 @@ badcsum:
  * is given as fp; otherwise have to make a chain.
  */
 struct mbuf *
-ip_reass(ipqe, fp, ipqhead)
-	struct ipqent *ipqe;
-	struct ipq *fp;
-	struct ipqhead *ipqhead;
+ip_reass(struct ipqent *ipqe, struct ipq *fp, struct ipqhead *ipqhead)
 {
 	struct mbuf *m = ipqe->ipqe_m;
 	struct ipqent *nq, *p, *q;
@@ -1226,8 +1244,7 @@ dropfrag:
  * associated datagrams.
  */
 void
-ip_freef(fp)
-	struct ipq *fp;
+ip_freef(struct ipq *fp)
 {
 	struct ipqent *q, *p;
 	u_int nfrags = 0;
@@ -1324,7 +1341,7 @@ ip_reass_drophalf(void)
  * queue, discard it.
  */
 void
-ip_slowtimo()
+ip_slowtimo(void)
 {
 	static u_int dropscanidx = 0;
 	u_int i;
@@ -1381,7 +1398,7 @@ ip_slowtimo()
  * Drain off all datagram fragments.
  */
 void
-ip_drain()
+ip_drain(void)
 {
 
 	/*
@@ -1408,8 +1425,7 @@ ip_drain()
  * 0 if the packet should be processed further.
  */
 int
-ip_dooptions(m)
-	struct mbuf *m;
+ip_dooptions(struct mbuf *m)
 {
 	struct ip *ip = mtod(m, struct ip *);
 	u_char *cp, *cp0;
@@ -1638,8 +1654,7 @@ bad:
  * return internet address info of interface to be used to get there.
  */
 struct in_ifaddr *
-ip_rtaddr(dst)
-	 struct in_addr dst;
+ip_rtaddr(struct in_addr dst)
 {
 	struct sockaddr_in *sin;
 
@@ -1666,9 +1681,7 @@ ip_rtaddr(dst)
  * to be picked up later by ip_srcroute if the receiver is interested.
  */
 void
-save_rte(option, dst)
-	u_char *option;
-	struct in_addr dst;
+save_rte(u_char *option, struct in_addr dst)
 {
 	unsigned olen;
 
@@ -1690,7 +1703,7 @@ save_rte(option, dst)
  * The first hop is placed before the options, will be removed later.
  */
 struct mbuf *
-ip_srcroute()
+ip_srcroute(void)
 {
 	struct in_addr *p, *q;
 	struct mbuf *m;
@@ -1762,9 +1775,7 @@ ip_srcroute()
  * XXX should be deleted; last arg currently ignored.
  */
 void
-ip_stripoptions(m, mopt)
-	struct mbuf *m;
-	struct mbuf *mopt;
+ip_stripoptions(struct mbuf *m, struct mbuf *mopt)
 {
 	int i;
 	struct ip *ip = mtod(m, struct ip *);
@@ -1806,9 +1817,7 @@ const int inetctlerrmap[PRC_NCMDS] = {
  * via a source route.
  */
 void
-ip_forward(m, srcrt)
-	struct mbuf *m;
-	int srcrt;
+ip_forward(struct mbuf *m, int srcrt)
 {
 	struct ip *ip = mtod(m, struct ip *);
 	struct sockaddr_in *sin;
@@ -2036,11 +2045,8 @@ ip_forward(m, srcrt)
 }
 
 void
-ip_savecontrol(inp, mp, ip, m)
-	struct inpcb *inp;
-	struct mbuf **mp;
-	struct ip *ip;
-	struct mbuf *m;
+ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
+    struct mbuf *m)
 {
 
 	if (inp->inp_socket->so_options & SO_TIMESTAMP) {
@@ -2328,4 +2334,11 @@ SYSCTL_SETUP(sysctl_net_inet_ip_setup, "
 		       NULL, 0, &ip_do_randomid, 0,
 		       CTL_NET, PF_INET, IPPROTO_IP,
 		       IPCTL_RANDOMID, CTL_EOL);
+	sysctl_createv(clog, 0, NULL, NULL,
+		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
+		       CTLTYPE_INT, "do_loopback_cksum",
+		       SYSCTL_DESCR("Perform IP checksum on loopback"),
+		       NULL, 0, &ip_do_loopback_cksum, 0,
+		       CTL_NET, PF_INET, IPPROTO_IP,
+		       IPCTL_LOOPBACKCKSUM, CTL_EOL);
 }