auto import from //depot/cupcake/@135843
diff --git a/libc/include/net/if_dl.h b/libc/include/net/if_dl.h
new file mode 100644
index 0000000..1f0c080
--- /dev/null
+++ b/libc/include/net/if_dl.h
@@ -0,0 +1,87 @@
+/* $NetBSD: if_dl.h,v 1.18 2005/12/11 23:05:24 thorpej Exp $ */
+
+/*
+ * Copyright (c) 1990, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * @(#)if_dl.h 8.1 (Berkeley) 6/10/93
+ */
+
+/*
+ * A Link-Level Sockaddr may specify the interface in one of two
+ * ways: either by means of a system-provided index number (computed
+ * anew and possibly differently on every reboot), or by a human-readable
+ * string such as "il0" (for managerial convenience).
+ *
+ * Census taking actions, such as something akin to SIOCGCONF would return
+ * both the index and the human name.
+ *
+ * High volume transactions (such as giving a link-level ``from'' address
+ * in a recvfrom or recvmsg call) may be likely only to provide the indexed
+ * form, (which requires fewer copy operations and less space).
+ *
+ * The form and interpretation of the link-level address is purely a matter
+ * of convention between the device driver and its consumers; however, it is
+ * expected that all drivers for an interface of a given if_type will agree.
+ */
+
+#ifndef _NET_IF_DL_H_
+#define _NET_IF_DL_H_
+
+#include <sys/socket.h>
+
+/*
+ * Structure of a Link-Level sockaddr:
+ */
+struct sockaddr_dl {
+ u_char sdl_len; /* Total length of sockaddr */
+ sa_family_t sdl_family; /* AF_LINK */
+ u_int16_t sdl_index; /* if != 0, system given index for interface */
+ u_char sdl_type; /* interface type */
+ u_char sdl_nlen; /* interface name length, no trailing 0 reqd. */
+ u_char sdl_alen; /* link level address length */
+ u_char sdl_slen; /* link layer selector length */
+ char sdl_data[12]; /* minimum work area, can be larger;
+ contains both if name and ll address */
+};
+
+/* We do arithmetic directly with these, so keep them char instead of void */
+#define LLADDR(s) ((char *)((s)->sdl_data + (s)->sdl_nlen))
+#define CLLADDR(s) ((const char *)((s)->sdl_data + (s)->sdl_nlen))
+
+#ifndef _KERNEL
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+void link_addr(const char *, struct sockaddr_dl *);
+char *link_ntoa(const struct sockaddr_dl *);
+__END_DECLS
+
+#endif /* !_KERNEL */
+
+#endif /* !_NET_IF_DL_H_ */