libifconfig: Add a function to get down reason

For use in ifconfig.

Reviewed by:	kp
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D28991

3 files changed, 20 insertions, 0 deletions

diff --git a/lib/libifconfig/Symbol.map b/lib/libifconfig/Symbol.map
index 4f82c8185d0b..b3e81d6ee497 100644
--- a/lib/libifconfig/Symbol.map
+++ b/lib/libifconfig/Symbol.map
@@ -31,6 +31,7 @@ FBSD_1.6 {
 	ifconfig_media_get_status;
 	ifconfig_media_get_subtype;
 	ifconfig_media_get_type;
+	ifconfig_media_get_downreason;
 	ifconfig_open;
 	ifconfig_set_capability;
 	ifconfig_set_description;
diff --git a/lib/libifconfig/libifconfig.h b/lib/libifconfig/libifconfig.h
index 46a13ae27d69..d8245ea13b23 100644
--- a/lib/libifconfig/libifconfig.h
+++ b/lib/libifconfig/libifconfig.h
@@ -207,6 +207,15 @@ const char *ifconfig_media_get_subtype(int ifmw);
 const char *ifconfig_media_get_status(const struct ifmediareq *ifmr);
 void ifconfig_media_get_options_string(int ifmw, char *buf, size_t buflen);
 
+/** Retrieve the reason the interface is down
+ * @param h	An open ifconfig state object
+ * @param name	The interface name
+ * @param ifdr	Return argument.
+ * @return	0 on success, nonzero on failure
+ */
+int ifconfig_media_get_downreason(ifconfig_handle_t *h, const char *name,
+    struct ifdownreason *ifdr);
+
 int ifconfig_carp_get_info(ifconfig_handle_t *h, const char *name,
     struct carpreq *carpr, int ncarpr);
 
diff --git a/lib/libifconfig/libifconfig_media.c b/lib/libifconfig/libifconfig_media.c
index f7302d8a9b24..d7ef507604be 100644
--- a/lib/libifconfig/libifconfig_media.c
+++ b/lib/libifconfig/libifconfig_media.c
@@ -392,3 +392,13 @@ ifconfig_media_get_options_string(int ifmw, char *buf, size_t buflen)
 		}
 	}
 }
+
+int
+ifconfig_media_get_downreason(ifconfig_handle_t *h, const char *name,
+    struct ifdownreason *ifdr)
+{
+
+	(void)memset(ifdr, 0, sizeof(*ifdr));
+	(void)strlcpy(ifdr->ifdr_name, name, sizeof(ifdr->ifdr_name));
+	return (ifconfig_ioctlwrap(h, AF_LOCAL, SIOCGIFDOWNREASON, ifdr));
+}