From c42bebbdd1ab596db6ade9bd27589b0045d0a4d1 Mon Sep 17 00:00:00 2001
From: Roy Marples <roy@marples.name>
Date: Thu, 8 Aug 2019 17:38:21 +0100
Subject: [PATCH] net/if: introduce if_bylla to find an interface by hardware
 address

---
 sys/net/if.c     | 25 +++++++++++++++++++++++++
 sys/net/if_var.h |  1 +
 2 files changed, 26 insertions(+)

diff --git a/sys/net/if.c b/sys/net/if.c
index be6670c63a..d82d23f620 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -2815,6 +2815,31 @@ if_setlladdr(struct ifnet *ifp, const u_char *lladdr, int len)
 	return (0);
 }
 
+
+/*
+ * Locate an interface based on a complete address.
+ */
+struct ifnet *
+if_bylla(const void *lla, unsigned char lla_len)
+{
+	const struct ifnet_array *arr;
+	struct ifnet *ifp;
+	struct sockaddr_dl *sdl;
+	int i;
+
+	arr = ifnet_array_get();
+	for (i = 0; i < arr->ifnet_count; ++i) {
+		ifp = arr->ifnet_arr[i];
+		if (ifp->if_addrlen != lla_len)
+			continue;
+
+		sdl = IF_LLSOCKADDR(ifp);
+		if (memcmp(lla, LLADDR(sdl), lla_len) == 0)
+			return (ifp);
+	}
+	return (NULL);
+}
+
 struct ifmultiaddr *
 ifmaof_ifpforaddr(struct sockaddr *sa, struct ifnet *ifp)
 {
diff --git a/sys/net/if_var.h b/sys/net/if_var.h
index 4e2c7ca14d..1f26883568 100644
--- a/sys/net/if_var.h
+++ b/sys/net/if_var.h
@@ -945,6 +945,7 @@ struct ifnet *if_alloc(uint8_t);
 void	if_free(struct ifnet *);
 void	if_route(struct ifnet *, int flag, int fam);
 int	if_setlladdr(struct ifnet *, const u_char *, int);
+struct ifnet *if_bylla(const void *, unsigned char);
 void	if_unroute(struct ifnet *, int flag, int fam);
 void	if_up(struct ifnet *);
 /*void	ifinit(void);*/ /* declared in systm.h for main() */
-- 
2.41.0