From: Roy Marples <roy@marples.name>
Date: Wed, 19 Jun 2013 16:02:19 +0000 (+0000)
Subject: Add a route from the IPv4 address to the loopback address.
X-Git-Tag: v6.0.0~5
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=bc349b818558ab09dabcbfc1a2dd724fe2df2c12;p=thirdparty%2Fdhcpcd.git

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 566ddeb4..96f483d9 100644
--- 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 567a1f23..c2be11d3 100644
--- 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);