MFC:

AF_LINK support for getnameinfo().

Obtained from:	NetBSD

lib/libc/net/getnameinfo.3

@@ -18,7 +18,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd December 20, 2004
+.Dd February 28, 2007
 .Dt GETNAMEINFO 3
 .Os
 .Sh NAME
@@ -47,15 +47,29 @@ functions and is the converse of the
 .Xr getaddrinfo 3
 function.
 .Pp
+If a link-layer address is passed to
+.Fn getnameinfo ,
+its ASCII representation will be stored in
+.Fa host .
+The string pointed to by
+.Fa serv
+will be set to the empty string if non-NULL;
+.Fa flags
+will always be ignored.
+This is intended as a replacement for the legacy
+.Xr link_ntoa 3
+function.
+.Pp
 The
 .Li sockaddr
 structure
 .Fa sa
 should point to either a
-.Li sockaddr_in
-or
+.Li sockaddr_in ,
 .Li sockaddr_in6
-structure (for IPv4 or IPv6 respectively) that is
+or
+.Li sockaddr_dl
+structure (for IPv4, IPv6 or link-layer respectively) that is
 .Fa salen
 bytes long.
 .Pp
@@ -166,6 +180,7 @@ printf("host=%s\en", hbuf);
 .Xr gethostbyaddr 3 ,
 .Xr getservbyport 3 ,
 .Xr inet_ntop 3 ,
+.Xr link_ntoa 3 ,
 .Xr resolver 3 ,
 .Xr hosts 5 ,
 .Xr resolv.conf 5 ,

lib/libc/net/getnameinfo.c

@@ -2,6 +2,7 @@
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
+ * Copyright (c) 2000 Ben Harris.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -49,6 +50,8 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <net/if.h>
+#include <net/if_dl.h>
+#include <net/if_types.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <arpa/nameser.h>
@@ -58,6 +61,38 @@ __FBSDID("$FreeBSD$");
 #include <stddef.h>
 #include <errno.h>
 
+static int	getnameinfo_inet(const struct sockaddr *, socklen_t, char *,
+    size_t, char *, size_t, int);
+#ifdef INET6
+static int ip6_parsenumeric(const struct sockaddr *, const char *, char *,
+    size_t, int);
+static int ip6_sa2str(const struct sockaddr_in6 *, char *, size_t, int);
+#endif
+static int	getnameinfo_link(const struct sockaddr *, socklen_t, char *,
+    size_t, char *, size_t, int);
+static int	hexname(const u_int8_t *, size_t, char *, size_t);
+
+int
+getnameinfo(const struct sockaddr *sa, socklen_t salen,
+    char *host, size_t hostlen, char *serv, size_t servlen,
+    int flags)
+{
+
+	switch (sa->sa_family) {
+	case AF_INET:
+#ifdef INET6
+	case AF_INET6:
+#endif
+		return getnameinfo_inet(sa, salen, host, hostlen, serv,
+		    servlen, flags);
+	case AF_LINK:
+		return getnameinfo_link(sa, salen, host, hostlen, serv,
+		    servlen, flags);
+	default:
+		return EAI_FAMILY;
+	}
+}
+
 static const struct afd {
 	int a_af;
 	size_t a_addrlen;
@@ -79,14 +114,8 @@ struct sockinet {
 	u_short	si_port;
 };
 
-#ifdef INET6
-static int ip6_parsenumeric(const struct sockaddr *, const char *, char *,
-    size_t, int);
-static int ip6_sa2str(const struct sockaddr_in6 *, char *, size_t, int);
-#endif
-
-int
-getnameinfo(const struct sockaddr *sa, socklen_t salen,
+static int
+getnameinfo_inet(const struct sockaddr *sa, socklen_t salen,
     char *host, size_t hostlen, char *serv, size_t servlen,
     int flags)
 {
@@ -343,3 +372,82 @@ ip6_sa2str(const struct sockaddr_in6 *sa6, char *buf, size_t bufsiz, int flags)
 		return n;
 }
 #endif /* INET6 */
+
+/*
+ * getnameinfo_link():
+ * Format a link-layer address into a printable format, paying attention to
+ * the interface type.
+ */
+/* ARGSUSED */
+static int
+getnameinfo_link(const struct sockaddr *sa, socklen_t salen,
+    char *host, size_t hostlen, char *serv, size_t servlen, int flags)
+{
+	const struct sockaddr_dl *sdl =
+	    (const struct sockaddr_dl *)(const void *)sa;
+	int n;
+
+	if (serv != NULL && servlen > 0)
+		*serv = '\0';
+
+	if (sdl->sdl_nlen == 0 && sdl->sdl_alen == 0 && sdl->sdl_slen == 0) {
+		n = snprintf(host, hostlen, "link#%d", sdl->sdl_index);
+		if (n > hostlen) {
+			*host = '\0';
+			return EAI_MEMORY;
+		}
+		return 0;
+	}
+
+	switch (sdl->sdl_type) {
+	/*
+	 * The following have zero-length addresses.
+	 * IFT_ATM	(net/if_atmsubr.c)
+	 * IFT_FAITH	(net/if_faith.c)
+	 * IFT_GIF	(net/if_gif.c)
+	 * IFT_LOOP	(net/if_loop.c)
+	 * IFT_PPP	(net/if_ppp.c, net/if_spppsubr.c)
+	 * IFT_SLIP	(net/if_sl.c, net/if_strip.c)
+	 * IFT_STF	(net/if_stf.c)
+	 * IFT_L2VLAN	(net/if_vlan.c)
+	 * IFT_BRIDGE (net/if_bridge.h>
+	 */
+	/*
+	 * The following use IPv4 addresses as link-layer addresses:
+	 * IFT_OTHER	(net/if_gre.c)
+	 * IFT_OTHER	(netinet/ip_ipip.c)
+	 */
+	/* default below is believed correct for all these. */
+	case IFT_ARCNET:
+	case IFT_ETHER:
+	case IFT_FDDI:
+	case IFT_HIPPI:
+	case IFT_ISO88025:
+	default:
+		return hexname((u_int8_t *)LLADDR(sdl), (size_t)sdl->sdl_alen,
+		    host, hostlen);
+	}
+}
+
+static int
+hexname(cp, len, host, hostlen)
+	const u_int8_t *cp;
+	char *host;
+	size_t len, hostlen;
+{
+	int i, n;
+	char *outp = host;
+
+	*outp = '\0';
+	for (i = 0; i < len; i++) {
+		n = snprintf(outp, hostlen, "%s%02x",
+		    i ? ":" : "", cp[i]);
+		if (n < 0 || n >= hostlen) {
+			*host = '\0';
+			return EAI_MEMORY;
+		}
+		outp += n;
+		hostlen -= n;
+	}
+	return 0;
+}