Add a route from the IPv4 address to the loopback address.

This allows for machine-internal communications to this address
can use the large loopback mtu.

diff --git a/if-bsd.c b/if-bsd.c
index 566ddeb4145631d0e2072df32285cdba06d5b6ba..96f483d92c94c1eb7b0455bacd801b2fb82d269c 100644 (file)
--- a/if-bsd.c
+++ b/if-bsd.c
@@ -260,6 +260,9 @@ if_route(const struct rt *rt, int action)
        if (rt->dest.s_addr == rt->gate.s_addr &&
            rt->net.s_addr == INADDR_BROADCAST)
                rtm.hdr.rtm_flags |= RTF_HOST;
+       else if (rt->gate.s_addr == htonl(INADDR_LOOPBACK) &&
+           rt->net.s_addr == INADDR_BROADCAST)
+               rtm.hdr.rtm_flags |= RTF_HOST | RTF_GATEWAY;
        else {
                rtm.hdr.rtm_addrs |= RTA_NETMASK;
                if (rtm.hdr.rtm_flags & RTF_STATIC)
@@ -269,7 +272,8 @@ if_route(const struct rt *rt, int action)
        }
 
        ADDADDR(&rt->dest);
-       if (rtm.hdr.rtm_flags & RTF_HOST ||
+       if ((rtm.hdr.rtm_flags & RTF_HOST &&
+           rt->gate.s_addr != htonl(INADDR_LOOPBACK)) ||
            !(rtm.hdr.rtm_flags & RTF_STATIC))
        {
                /* Make us a link layer socket for the host gateway */

diff --git a/ipv4.c b/ipv4.c
index 567a1f23eed2defd2c48178c06612f79364e8141..c2be11d32daa0741bd268b9f4fbf5f3e6547fff2 100644 (file)
--- a/ipv4.c
+++ b/ipv4.c
@@ -229,6 +229,10 @@ desc_route(const char *cmd, const struct rt *rt)
            rt->net.s_addr == INADDR_BROADCAST)
                syslog(LOG_INFO, "%s: %s host route to %s", ifname, cmd,
                    addr);
+       else if (rt->gate.s_addr == htonl(INADDR_LOOPBACK) &&
+           rt->net.s_addr == INADDR_BROADCAST)
+               syslog(LOG_INFO, "%s: %s host route to %s via %s", ifname, cmd,
+                   addr, inet_ntoa(rt->gate));
        else if (rt->dest.s_addr == INADDR_ANY && rt->net.s_addr == INADDR_ANY)
                syslog(LOG_INFO, "%s: %s default route via %s", ifname, cmd,
                    inet_ntoa(rt->gate));
@@ -341,6 +345,32 @@ add_subnet_route(struct rt_head *rt, const struct interface *ifp)
        return rt;
 }
 
+static struct rt_head *
+add_loopback_route(struct rt_head *rt, const struct interface *ifp)
+{
+       struct rt *r;
+       const struct dhcp_state *s;
+
+       if (rt == NULL) /* earlier malloc failed */
+               return NULL;
+
+       s = D_CSTATE(ifp);
+       if (s->addr.s_addr == INADDR_ANY)
+               return rt;
+
+       r = malloc(sizeof(*r));
+       if (r == NULL) {
+               syslog(LOG_ERR, "%s: %m", __func__);
+               ipv4_freeroutes(rt);
+               return NULL;
+       }
+       r->dest.s_addr = s->addr.s_addr;
+       r->net.s_addr = INADDR_BROADCAST;
+       r->gate.s_addr = htonl(INADDR_LOOPBACK);
+       TAILQ_INSERT_HEAD(rt, r, next);
+       return rt;
+}
+
 static struct rt_head *
 get_routes(struct interface *ifp)
 {
@@ -488,6 +518,7 @@ ipv4_buildroutes(void)
                dnr = get_routes(ifp);
                dnr = massage_host_routes(dnr, ifp);
                dnr = add_subnet_route(dnr, ifp);
+               dnr = add_loopback_route(dnr, ifp);
                if (ifp->options->options & DHCPCD_GATEWAY) {
                        dnr = add_router_host_route(dnr, ifp);
                        dnr = add_destination_route(dnr, ifp);