ipv4: Make rt->fl.iif tests lest obscure.

When we test rt->fl.iif against zero, we're seeing if it's
an output or an input route.

Make that explicit with some helper functions.

Signed-off-by: David S. Miller <davem@davemloft.net>

7 files changed, 22 insertions, 20 deletions

diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index 94a9eb1d313e..474d54dd08c2 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -1181,7 +1181,7 @@ static int __dn_route_output_key(struct dst_entry **pprt, const struct flowi *fl
                         if ((flp->fld_dst == rt->fl.fld_dst) &&
                             (flp->fld_src == rt->fl.fld_src) &&
                             (flp->mark == rt->fl.mark) &&
-                            (rt->fl.iif == 0) &&
+                            dn_is_output_route(rt) &&
                             (rt->fl.oif == flp->oif)) {
                                 dst_use(&rt->dst, jiffies);
                                 rcu_read_unlock_bh();
@@ -1512,7 +1512,7 @@ static int dn_rt_fill_info(struct sk_buff *skb, u32 pid, u32 seq,
         if (rtnl_put_cacheinfo(skb, &rt->dst, 0, 0, 0, expires,
                                rt->dst.error) < 0)
                 goto rtattr_failure;
-        if (rt->fl.iif)
+        if (dn_is_input_route(rt))
                 RTA_PUT(skb, RTA_IIF, sizeof(int), &rt->fl.iif);
 
         nlh->nlmsg_len = skb_tail_pointer(skb) - b;
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 96bc7f9475a3..c6e2affafbd3 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -506,8 +506,8 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
                 struct net_device *dev = NULL;
 
                 rcu_read_lock();
-                if (rt->fl.iif &&
-                        net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
+                if (rt_is_input_route(rt) &&
+                    net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
                         dev = dev_get_by_index_rcu(net, rt->fl.iif);
 
                 if (dev)
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index c8877c6c7216..08d0d81ffc15 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -961,7 +961,7 @@ int igmp_rcv(struct sk_buff *skb)
         case IGMP_HOST_MEMBERSHIP_REPORT:
         case IGMPV2_HOST_MEMBERSHIP_REPORT:
                 /* Is it our report looped back? */
-                if (skb_rtable(skb)->fl.iif == 0)
+                if (rt_is_output_route(skb_rtable(skb)))
                         break;
                 /* don't rely on MC router hearing unicast reports */
                 if (skb->pkt_type == PACKET_MULTICAST ||
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 70ff77f02eee..cab2057d5430 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -634,7 +634,7 @@ static int ipgre_rcv(struct sk_buff *skb)
 #ifdef CONFIG_NET_IPGRE_BROADCAST
                 if (ipv4_is_multicast(iph->daddr)) {
                         /* Looped back packet, drop it! */
-                        if (skb_rtable(skb)->fl.iif == 0)
+                        if (rt_is_output_route(skb_rtable(skb)))
                                 goto drop;
                         tunnel->dev->stats.multicast++;
                         skb->pkt_type = PACKET_BROADCAST;
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 86dd5691af46..ef2b0089e0ea 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1654,7 +1654,7 @@ static int ip_mr_forward(struct net *net, struct mr_table *mrt,
         if (mrt->vif_table[vif].dev != skb->dev) {
                 int true_vifi;
 
-                if (skb_rtable(skb)->fl.iif == 0) {
+                if (rt_is_output_route(skb_rtable(skb))) {
                         /* It is our own packet, looped back.
                          * Very complicated situation...
                          *
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 5955965c7953..66610ea3c87b 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -623,7 +623,7 @@ static inline int rt_fast_clean(struct rtable *rth)
         /* Kill broadcast/multicast entries very aggresively, if they
            collide in hash table with more useful entries */
         return (rth->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) &&
-                rth->fl.iif && rth->dst.rt_next;
+                rt_is_input_route(rth) && rth->dst.rt_next;
 }
 
 static inline int rt_valuable(struct rtable *rth)
@@ -668,7 +668,7 @@ static inline u32 rt_score(struct rtable *rt)
         if (rt_valuable(rt))
                 score |= (1<<31);
 
-        if (!rt->fl.iif ||
+        if (rt_is_output_route(rt) ||
             !(rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST|RTCF_LOCAL)))
                 score |= (1<<30);
 
@@ -1126,7 +1126,7 @@ restart:
                  */
 
                 rt->dst.flags |= DST_NOCACHE;
-                if (rt->rt_type == RTN_UNICAST || rt->fl.iif == 0) {
+                if (rt->rt_type == RTN_UNICAST || rt_is_output_route(rt)) {
                         int err = arp_bind_neighbour(&rt->dst);
                         if (err) {
                                 if (net_ratelimit())
@@ -1224,7 +1224,7 @@ restart:
         /* Try to bind route to arp only if it is output
            route or unicast forwarding path.
          */
-        if (rt->rt_type == RTN_UNICAST || rt->fl.iif == 0) {
+        if (rt->rt_type == RTN_UNICAST || rt_is_output_route(rt)) {
                 int err = arp_bind_neighbour(&rt->dst);
                 if (err) {
                         spin_unlock_bh(rt_hash_lock_addr(hash));
@@ -1406,7 +1406,7 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
                                 if (rth->fl.fl4_dst != daddr ||
                                     rth->fl.fl4_src != skeys[i] ||
                                     rth->fl.oif != ikeys[k] ||
-                                    rth->fl.iif != 0 ||
+                                    rt_is_input_route(rth) ||
                                     rt_is_expired(rth) ||
                                     !net_eq(dev_net(rth->dst.dev), net)) {
                                         rthp = &rth->dst.rt_next;
@@ -1666,7 +1666,7 @@ unsigned short ip_rt_frag_needed(struct net *net, struct iphdr *iph,
                                     rth->rt_dst != daddr ||
                                     rth->rt_src != iph->saddr ||
                                     rth->fl.oif != ikeys[k] ||
-                                    rth->fl.iif != 0 ||
+                                    rt_is_input_route(rth) ||
                                     dst_metric_locked(&rth->dst, RTAX_MTU) ||
                                     !net_eq(dev_net(rth->dst.dev), net) ||
                                     rt_is_expired(rth))
@@ -1770,7 +1770,7 @@ void ip_rt_get_source(u8 *addr, struct rtable *rt)
         __be32 src;
         struct fib_result res;
 
-        if (rt->fl.iif == 0)
+        if (rt_is_output_route(rt))
                 src = rt->rt_src;
         else {
                 rcu_read_lock();
@@ -2669,7 +2669,7 @@ int __ip_route_output_key(struct net *net, struct rtable **rp,
                 rth = rcu_dereference_bh(rth->dst.rt_next)) {
                 if (rth->fl.fl4_dst == flp->fl4_dst &&
                     rth->fl.fl4_src == flp->fl4_src &&
-                    rth->fl.iif == 0 &&
+                    rt_is_output_route(rth) &&
                     rth->fl.oif == flp->oif &&
                     rth->fl.mark == flp->mark &&
                     !((rth->fl.fl4_tos ^ flp->fl4_tos) &
@@ -2824,7 +2824,7 @@ static int rt_fill_info(struct net *net,
         if (rt->dst.tclassid)
                 NLA_PUT_U32(skb, RTA_FLOW, rt->dst.tclassid);
 #endif
-        if (rt->fl.iif)
+        if (rt_is_input_route(rt))
                 NLA_PUT_BE32(skb, RTA_PREFSRC, rt->rt_spec_dst);
         else if (rt->rt_src != rt->fl.fl4_src)
                 NLA_PUT_BE32(skb, RTA_PREFSRC, rt->rt_src);
@@ -2849,7 +2849,7 @@ static int rt_fill_info(struct net *net,
                 }
         }
 
-        if (rt->fl.iif) {
+        if (rt_is_input_route(rt)) {
 #ifdef CONFIG_IP_MROUTE
                 __be32 dst = rt->rt_dst;
 
diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index de04ea39cde8..10bd39c0ae2d 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -169,7 +169,7 @@ __ip_vs_reroute_locally(struct sk_buff *skb)
         struct net *net = dev_net(dev);
         struct iphdr *iph = ip_hdr(skb);
 
-        if (rt->fl.iif) {
+        if (rt_is_input_route(rt)) {
                 unsigned long orefdst = skb->_skb_refdst;
 
                 if (ip_route_input(skb, iph->daddr, iph->saddr,
@@ -552,7 +552,8 @@ ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 #endif
 
         /* From world but DNAT to loopback address? */
-        if (local && ipv4_is_loopback(rt->rt_dst) && skb_rtable(skb)->fl.iif) {
+        if (local && ipv4_is_loopback(rt->rt_dst) &&
+            rt_is_input_route(skb_rtable(skb))) {
                 IP_VS_DBG_RL_PKT(1, AF_INET, pp, skb, 0, "ip_vs_nat_xmit(): "
                                  "stopping DNAT to loopback address");
                 goto tx_error_put;
@@ -1165,7 +1166,8 @@ ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 #endif
 
         /* From world but DNAT to loopback address? */
-        if (local && ipv4_is_loopback(rt->rt_dst) && skb_rtable(skb)->fl.iif) {
+        if (local && ipv4_is_loopback(rt->rt_dst) &&
+            rt_is_input_route(skb_rtable(skb))) {
                 IP_VS_DBG(1, "%s(): "
                           "stopping DNAT to loopback %pI4\n",
                           __func__, &cp->daddr.ip);