ra: always send current hop limit

3 files changed, 12 insertions, 9 deletions

diff --git a/src/odhcpd.c b/src/odhcpd.c
index 52bca13..aad5b37 100644
--- a/src/odhcpd.c
+++ b/src/odhcpd.c
@@ -113,11 +113,11 @@ int odhcpd_open_rtnl(void)
 
 
 // Read IPv6 MTU for interface
-int odhcpd_get_interface_mtu(const char *ifname)
+int odhcpd_get_interface_config(const char *ifname, const char *what)
 {
 	char buf[64];
-	const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/mtu";
-	snprintf(buf, sizeof(buf), sysctl_pattern, ifname);
+	const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/%s";
+	snprintf(buf, sizeof(buf), sysctl_pattern, ifname, what);
 
 	int fd = open(buf, O_RDONLY);
 	ssize_t len = read(fd, buf, sizeof(buf) - 1);
@@ -126,10 +126,8 @@ int odhcpd_get_interface_mtu(const char *ifname)
 	if (len < 0)
 		return -1;
 
-
 	buf[len] = 0;
 	return atoi(buf);
-
 }
 
 
diff --git a/src/odhcpd.h b/src/odhcpd.h
index 21dc99f..5944661 100644
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -186,7 +186,7 @@ ssize_t odhcpd_get_interface_addresses(int ifindex,
 		struct odhcpd_ipaddr *addrs, size_t cnt);
 int odhcpd_get_preferred_interface_address(int ifindex, struct in6_addr *addr);
 struct interface* odhcpd_get_interface_by_name(const char *name);
-int odhcpd_get_interface_mtu(const char *ifname);
+int odhcpd_get_interface_config(const char *ifname, const char *what);
 int odhcpd_get_mac(const struct interface *iface, uint8_t mac[6]);
 struct interface* odhcpd_get_interface_by_index(int ifindex);
 struct interface* odhcpd_get_master_interface(void);
diff --git a/src/router.c b/src/router.c
index 60d6b3f..f942d8f 100644
--- a/src/router.c
+++ b/src/router.c
@@ -209,9 +209,11 @@ static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
 // Router Advert server mode
 static uint64_t send_router_advert(struct interface *iface, const struct in6_addr *from)
 {
-	int mtu = odhcpd_get_interface_mtu(iface->ifname);
-	if (mtu < 0)
-		mtu = 1500;
+	int mtu = odhcpd_get_interface_config(iface->ifname, "mtu");
+	int hlim = odhcpd_get_interface_config(iface->ifname, "hop_limit");
+
+	if (mtu < 1280)
+		mtu = 1280;
 
 	struct {
 		struct nd_router_advert h;
@@ -224,6 +226,9 @@ static uint64_t send_router_advert(struct interface *iface, const struct in6_add
 		.mtu = {ND_OPT_MTU, 1, 0, htonl(mtu)},
 	};
 
+	if (hlim > 0)
+		adv.h.nd_ra_curhoplimit = hlim;
+
 	if (iface->dhcpv6)
 		adv.h.nd_ra_flags_reserved = ND_RA_FLAG_OTHER;