Author: eri
Date: Wed Jul 29 17:46:16 2015
New Revision: 286025
URL: https://svnweb.freebsd.org/changeset/base/286025

Log:
  MFC r285051
  Avoid doing multiple route lookups for the same destination IP during 
forwarding.
  
  Differential Revision:        https://reviews.freebsd.org/D2964

Modified:
  stable/10/sys/netinet/ip_input.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/netinet/ip_input.c
==============================================================================
--- stable/10/sys/netinet/ip_input.c    Wed Jul 29 17:34:26 2015        
(r286024)
+++ stable/10/sys/netinet/ip_input.c    Wed Jul 29 17:46:16 2015        
(r286025)
@@ -1345,6 +1345,7 @@ ip_forward(struct mbuf *m, int srcrt)
        struct ip *ip = mtod(m, struct ip *);
        struct in_ifaddr *ia;
        struct mbuf *mcopy;
+       struct sockaddr_in *sin;
        struct in_addr dest;
        struct route ro;
        int error, type = 0, code = 0, mtu = 0;
@@ -1366,7 +1367,22 @@ ip_forward(struct mbuf *m, int srcrt)
        }
 #endif
 
-       ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
+       bzero(&ro, sizeof(ro));
+       sin = (struct sockaddr_in *)&ro.ro_dst;
+       sin->sin_family = AF_INET;
+       sin->sin_len = sizeof(*sin);
+       sin->sin_addr = ip->ip_dst;
+#ifdef RADIX_MPATH
+       rtalloc_mpath_fib(&ro,
+           ntohl(ip->ip_src.s_addr ^ ip->ip_dst.s_addr),
+           M_GETFIB(m));
+#else
+       in_rtalloc_ign(&ro, 0, M_GETFIB(m));
+#endif
+       if (ro.ro_rt != NULL) {
+               ia = ifatoia(ro.ro_rt->rt_ifa);
+               ifa_ref(&ia->ia_ifa);
+       }
 #ifndef IPSEC
        /*
         * 'ia' may be NULL if there is no route for this destination.
@@ -1375,6 +1391,7 @@ ip_forward(struct mbuf *m, int srcrt)
         */
        if (!srcrt && ia == NULL) {
                icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
+               RO_RTFREE(&ro);
                return;
        }
 #endif
@@ -1431,16 +1448,8 @@ ip_forward(struct mbuf *m, int srcrt)
        dest.s_addr = 0;
        if (!srcrt && V_ipsendredirects &&
            ia != NULL && ia->ia_ifp == m->m_pkthdr.rcvif) {
-               struct sockaddr_in *sin;
                struct rtentry *rt;
 
-               bzero(&ro, sizeof(ro));
-               sin = (struct sockaddr_in *)&ro.ro_dst;
-               sin->sin_family = AF_INET;
-               sin->sin_len = sizeof(*sin);
-               sin->sin_addr = ip->ip_dst;
-               in_rtalloc_ign(&ro, 0, M_GETFIB(m));
-
                rt = ro.ro_rt;
 
                if (rt && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
@@ -1459,16 +1468,8 @@ ip_forward(struct mbuf *m, int srcrt)
                                code = ICMP_REDIRECT_HOST;
                        }
                }
-               if (rt)
-                       RTFREE(rt);
        }
 
-       /*
-        * Try to cache the route MTU from ip_output so we can consider it for
-        * the ICMP_UNREACH_NEEDFRAG "Next-Hop MTU" field described in RFC1191.
-        */
-       bzero(&ro, sizeof(ro));
-
        error = ip_output(m, NULL, &ro, IP_FORWARDING, NULL, NULL);
 
        if (error == EMSGSIZE && ro.ro_rt)
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