Move route state into it's own flag.

Instead of setting the interface MTU directly, set the MTU for each of the
routes derived from the DHCP message in the same way we do for IPv6 RA.

dhcp.c

@@ -275,6 +275,23 @@ get_option_uint32(struct dhcpcd_ctx *ctx,
 	return 0;
 }
 
+static int
+get_option_uint16(struct dhcpcd_ctx *ctx,
+    uint16_t *i, const struct dhcp_message *dhcp, uint8_t option)
+{
+	const uint8_t *p;
+	size_t len;
+	uint16_t d;
+
+	p = get_option(ctx, dhcp, option, &len);
+	if (!p || len < (ssize_t)sizeof(d))
+		return -1;
+	memcpy(&d, p, sizeof(d));
+	if (i)
+		*i = ntohs(d);
+	return 0;
+}
+
 static int
 get_option_uint8(struct dhcpcd_ctx *ctx,
     uint8_t *i, const struct dhcp_message *dhcp, uint8_t option)
@@ -583,7 +600,7 @@ route_netmask(uint32_t ip_in)
 /* We need to obey routing options.
  * If we have a CSR then we only use that.
  * Otherwise we add static routes and then routers. */
-struct rt_head *
+static struct rt_head *
 get_option_routes(struct interface *ifp, const struct dhcp_message *dhcp)
 {
 	struct if_options *ifo = ifp->options;
@@ -689,6 +706,40 @@ get_option_routes(struct interface *ifp, const struct dhcp_message *dhcp)
 	return routes;
 }
 
+uint16_t
+dhcp_get_mtu(const struct interface *ifp)
+{
+	const struct dhcp_message *dhcp;
+	uint16_t mtu;
+
+	if ((dhcp = D_CSTATE(ifp)->new) == NULL ||
+	    has_option_mask(ifp->options->nomask, DHO_MTU) ||
+	    get_option_uint16(ifp->ctx, &mtu, dhcp, DHO_MTU) == -1)
+		return 0;
+	return mtu;
+}
+
+/* Grab our routers from the DHCP message and apply any MTU value
+ * the message contains */
+struct rt_head *
+dhcp_get_routes(struct interface *ifp)
+{
+	struct rt_head *routes;
+	uint16_t mtu;
+	const struct dhcp_message *dhcp;
+
+	dhcp = D_CSTATE(ifp)->new;
+	routes = get_option_routes(ifp, dhcp);
+	if ((mtu = dhcp_get_mtu(ifp)) != 0) {
+		struct rt *rt;
+
+		TAILQ_FOREACH(rt, routes, next) {
+			rt->mtu = mtu;
+		}
+	}
+	return routes;
+}
+
 #define PUTADDR(_type, _val)						      \
 	{								      \
 		*p++ = _type;						      \

dhcp.h

@@ -245,8 +245,8 @@ int get_option_addr(struct dhcpcd_ctx *,struct in_addr *,
     const struct dhcp_message *, uint8_t);
 #define IS_BOOTP(i, m) ((m) != NULL &&						    \
 	    get_option_uint8((i)->ctx, NULL, (m), DHO_MESSAGETYPE) == -1)
-struct rt_head *get_option_routes(struct interface *,
-    const struct dhcp_message *);
+uint16_t dhcp_get_mtu(const struct interface *);
+struct rt_head *dhcp_get_routes(struct interface *);
 ssize_t dhcp_env(char **, const char *, const struct dhcp_message *,
     const struct interface *);
 

dhcpcd-hooks/Makefile

@@ -4,7 +4,7 @@ include ${TOP}/iconfig.mk
 
 SCRIPTSDIR=	${LIBEXECDIR}/dhcpcd-hooks
 SCRIPTS=	01-test 02-dump
-SCRIPTS+=	10-mtu 10-wpa_supplicant 15-timezone 20-resolv.conf
+SCRIPTS+=	10-wpa_supplicant 15-timezone 20-resolv.conf
 SCRIPTS+=	29-lookup-hostname 30-hostname
 SCRIPTS+=	${HOOKSCRIPTS}
 

dhcpcd.8.in

@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd July 3, 2015
+.Dd July 28, 2015
 .Dt DHCPCD 8
 .Os
 .Sh NAME
@@ -551,8 +551,8 @@ Matches full name, or prefixed with 2 numbers optionally ending with
 .Pp
 So to stop
 .Nm
-from touching your DNS or MTU settings you would do:-
-.D1 dhcpcd -C resolv.conf -C mtu eth0
+from touching your DNS settings you would do:-
+.D1 dhcpcd -C resolv.conf eth0
 .It Fl G , Fl Fl nogateway
 Don't set any default routes.
 .It Fl H , Fl Fl xidhwaddr

dhcpcd.conf

@@ -28,9 +28,8 @@ option domain_name_servers, domain_name, domain_search, host_name
 option classless_static_routes
 # Most distributions have NTP support.
 option ntp_servers
-# Respect the network MTU.
-# Some interface drivers reset when changing the MTU so disabled by default.
-#option interface_mtu
+# Respect the network MTU. This is applied to DHCP routes.
+option interface_mtu
 
 # A ServerID is required by RFC2131.
 require dhcp_server_identifier

dhcpcd.conf.5.in

@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd July 22, 2015
+.Dd July 28, 2015
 .Dt DHCPCD.CONF 5
 .Os
 .Sh NAME
@@ -430,8 +430,8 @@ Matches full name, or prefixed with 2 numbers optionally ending with
 .Pp
 So to stop
 .Nm dhcpcd
-from touching your DNS or MTU settings you would do:-
-.D1 nohook resolv.conf, mtu
+from touching your DNS settings or starting wpa_supplicant you would do:-
+.D1 nohook resolv.conf, wpa_supplicant
 .It Ic noipv4
 Don't attempt to configure an IPv4 address.
 .It Ic noipv4ll

if-bsd.c

@@ -500,6 +500,7 @@ if_copyrt(struct dhcpcd_ctx *ctx, struct rt *rt, struct rt_msghdr *rtm)
 
 	get_addrs(rtm->rtm_addrs, cp, rti_info);
 	memset(rt, 0, sizeof(*rt));
+	rt->flags = (unsigned int)rtm->rtm_flags;
 	COPYOUT(rt->dest, rti_info[RTAX_DST]);
 	if (rtm->rtm_addrs & RTA_NETMASK)
 		COPYOUT(rt->net, rti_info[RTAX_NETMASK]);
@@ -508,6 +509,9 @@ if_copyrt(struct dhcpcd_ctx *ctx, struct rt *rt, struct rt_msghdr *rtm)
 	COPYOUT(rt->gate, rti_info[RTAX_GATEWAY]);
 	COPYOUT(rt->src, rti_info[RTAX_IFA]);
 
+	if (rtm->rtm_inits & RTV_MTU)
+		rt->mtu = (unsigned int)rtm->rtm_rmx.rmx_mtu;
+
 	if (rtm->rtm_index)
 		rt->iface = if_findindex(ctx->ifaces, rtm->rtm_index);
 	else if (rtm->rtm_addrs & RTA_IFP) {
@@ -516,6 +520,7 @@ if_copyrt(struct dhcpcd_ctx *ctx, struct rt *rt, struct rt_msghdr *rtm)
 		sdl = (struct sockaddr_dl *)(void *)rti_info[RTAX_IFP];
 		rt->iface = if_findsdl(ctx, sdl);
 	}
+
 	/* If we don't have an interface and it's a host route, it maybe
 	 * to a local ip via the loopback interface. */
 	if (rt->iface == NULL &&
@@ -658,6 +663,11 @@ if_route(unsigned char cmd, const struct rt *rt)
 
 		if (rtm.hdr.rtm_addrs & RTA_IFA)
 			ADDADDR(&state->addr);
+
+		if (rt->mtu) {
+			rtm.hdr.rtm_inits |= RTV_MTU;
+			rtm.hdr.rtm_rmx.rmx_mtu = rt->mtu;
+		}
 	}
 
 #undef ADDADDR
@@ -897,6 +907,9 @@ if_copyrt6(struct dhcpcd_ctx *ctx, struct rt6 *rt, struct rt_msghdr *rtm)
 		ipv6_mask(&rt->net, 128);
 	COPYOUT6(rt->gate, rti_info[RTAX_GATEWAY]);
 
+	if (rtm->rtm_inits & RTV_MTU)
+		rt->mtu = (unsigned int)rtm->rtm_rmx.rmx_mtu;
+
 	if (rtm->rtm_index)
 		rt->iface = if_findindex(ctx->ifaces, rtm->rtm_index);
 	else if (rtm->rtm_addrs & RTA_IFP) {

if-linux.c

@@ -922,6 +922,27 @@ add_attr_32(struct nlmsghdr *n, unsigned short maxlen, unsigned short type,
 	return 0;
 }
 
+static int
+rta_add_attr_32(struct rtattr *rta, unsigned short maxlen,
+    unsigned short type, uint32_t data)
+{
+	unsigned short len = RTA_LENGTH(sizeof(data));
+	struct rtattr *subrta;
+
+	if (RTA_ALIGN(rta->rta_len) + len > maxlen) {
+		errno = ENOBUFS;
+		return -1;
+	}
+
+	subrta = (struct rtattr*)(void *)
+	    (((char*)rta) + RTA_ALIGN(rta->rta_len));
+	subrta->rta_type = type;
+	subrta->rta_len = len;
+	memcpy(RTA_DATA(subrta), &data, sizeof(data));
+	rta->rta_len = (unsigned short)(NLMSG_ALIGN(rta->rta_len) + len);
+	return 0;
+}
+
 #ifdef HAVE_NL80211_H
 static struct nlattr *
 nla_next(struct nlattr *nla, size_t *rem)
@@ -1374,6 +1395,17 @@ if_route(unsigned char cmd, const struct rt *rt)
 	if (rt->metric)
 		add_attr_32(&nlm.hdr, sizeof(nlm), RTA_PRIORITY, rt->metric);
 
+	if (cmd != RTM_DELETE && rt->mtu) {
+		char metricsbuf[32];
+		struct rtattr *metrics = (void *)metricsbuf;
+
+		metrics->rta_type = RTA_METRICS;
+		metrics->rta_len = RTA_LENGTH(0);
+		rta_add_attr_32(metrics, sizeof(metricsbuf), RTAX_MTU, rt->mtu);
+		add_attr_l(&nlm.hdr, sizeof(nlm), RTA_METRICS,
+		    RTA_DATA(metrics), (unsigned short)RTA_PAYLOAD(metrics));
+	}
+
 	if (send_netlink(rt->iface->ctx, NULL,
 	    NETLINK_ROUTE, &nlm.hdr, NULL) == -1)
 		retval = -1;
@@ -1488,27 +1520,6 @@ if_address6(const struct ipv6_addr *ap, int action)
 	return retval;
 }
 
-static int
-rta_add_attr_32(struct rtattr *rta, unsigned short maxlen,
-    unsigned short type, uint32_t data)
-{
-	unsigned short len = RTA_LENGTH(sizeof(data));
-	struct rtattr *subrta;
-
-	if (RTA_ALIGN(rta->rta_len) + len > maxlen) {
-		errno = ENOBUFS;
-		return -1;
-	}
-
-	subrta = (struct rtattr*)(void *)
-	    (((char*)rta) + RTA_ALIGN(rta->rta_len));
-	subrta->rta_type = type;
-	subrta->rta_len = len;
-	memcpy(RTA_DATA(subrta), &data, sizeof(data));
-	rta->rta_len = (unsigned short)(NLMSG_ALIGN(rta->rta_len) + len);
-	return 0;
-}
-
 int
 if_route6(unsigned char cmd, const struct rt6 *rt)
 {
@@ -1565,7 +1576,7 @@ if_route6(unsigned char cmd, const struct rt6 *rt)
 			add_attr_32(&nlm.hdr, sizeof(nlm),
 			    RTA_PRIORITY, rt->metric);
 	}
-	if (cmd == RTM_ADD && rt->mtu) {
+	if (cmd != RTM_DELETE && rt->mtu) {
 		char metricsbuf[32];
 		struct rtattr *metrics = (void *)metricsbuf;