/* Host name canonicalization
- Copyright (C) 1995 Free Software Foundation, Inc.
+ Copyright (C) 1995, 1999, 2000, 2002, 2003, 2004, 2005 Free Software
+ Foundation, Inc.
Written by Miles Bader <miles@gnu.ai.mit.edu>
General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software
- Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
#ifdef HAVE_CONFIG_H
-#include <config.h>
+# include <config.h>
#endif
+#include <sys/types.h>
#ifdef HAVE_UNISTD_H
-#include <unistd.h>
+# include <unistd.h>
#endif
-#ifdef HAVE_STRING_H
+#include <stdlib.h>
#include <string.h>
-#endif
#ifdef HAVE_NETDB_H
-#include <netdb.h>
+# include <netdb.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+# include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
-#include <netinet/in.h>
+# include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
-#include <arpa/inet.h>
+# include <arpa/inet.h>
#endif
+#include "strdup.h"
+
/* Returns the canonical hostname associated with HOST (allocated in a static
- buffer), or 0 if it can't be determined. */
+ buffer), or NULL if it can't be determined. */
char *
-canon_host (host)
- char *host;
+canon_host (char const *host)
{
-#ifdef HAVE_GETHOSTBYNAME
- struct hostent *he = gethostbyname (host);
+ char *h_addr_copy = NULL;
+
+#if HAVE_GETADDRINFO
+ {
+ struct addrinfo hint = { 0, };
+ struct addrinfo *res = NULL;
+ hint.ai_flags = AI_CANONNAME;
+ if (getaddrinfo (host, NULL, &hint, &res) == 0)
+ {
+ h_addr_copy = strdup (res->ai_canonname);
+ freeaddrinfo (res);
+ }
+ }
+#elif HAVE_GETHOSTBYNAME
+ {
+ struct hostent *he = gethostbyname (host);
+
+ if (he)
+ {
+# ifdef HAVE_GETHOSTBYADDR
+ char *addr = NULL;
+
+ /* Try and get an ascii version of the numeric host address. */
+ switch (he->h_addrtype)
+ {
+# ifdef HAVE_INET_NTOA
+ case AF_INET:
+ addr = inet_ntoa (*(struct in_addr *) he->h_addr);
+ break;
+# endif /* HAVE_INET_NTOA */
+ }
+
+ if (addr && strcmp (he->h_name, addr) == 0)
+ {
+ /* gethostbyname has returned a string representation of the IP
+ address, for example, "127.0.0.1". So now, look up the host
+ name via the address. Although it may seem reasonable to look
+ up the host name via the address, we must not pass `he->h_addr'
+ directly to gethostbyaddr because on some systems he->h_addr
+ is located in a static library buffer that is reused in the
+ gethostbyaddr call. Make a copy and use that instead. */
+ h_addr_copy = (char *) malloc (he->h_length);
+ if (h_addr_copy == NULL)
+ he = NULL;
+ else
+ {
+ memcpy (h_addr_copy, he->h_addr, he->h_length);
+ he = gethostbyaddr (h_addr_copy, he->h_length, he->h_addrtype);
+ free (h_addr_copy);
+ }
+ }
+# endif /* HAVE_GETHOSTBYADDR */
- if (he)
+ if (he)
+ h_addr_copy = strdup (he->h_name);
+ }
+ }
+#endif /* HAVE_GETHOSTBYNAME */
+
+ return h_addr_copy;
+}
+
+#ifdef TEST_CANON_HOST
+int
+main (int argc, char **argv)
+{
+ int i;
+ for (i = 1; i < argc; i++)
{
-#ifdef HAVE_GETHOSTBYADDR
- char *addr = 0;
-
- /* Try and get an ascii version of the numeric host address. */
- switch (he->h_addrtype)
- {
-#ifdef HAVE_INET_NTOA
- case AF_INET:
- addr = inet_ntoa (*(struct in_addr *) he->h_addr);
- break;
-#endif /* HAVE_INET_NTOA */
- }
-
- if (addr && strcmp (he->h_name, addr) == 0)
- /* gethostbyname() cheated! Lookup the host name via the address
- this time to get the actual host name. */
- he = gethostbyaddr (he->h_addr, he->h_length, he->h_addrtype);
-#endif /* HAVE_GETHOSTBYADDR */
-
- if (he)
- return (char *) (he->h_name);
+ char *s = canon_host (argv[i]);
+ printf ("%s: %s\n", argv[i], (s ? s : "<undef>"));
}
-#endif /* HAVE_GETHOSTBYNAME */
- return 0;
+ exit (0);
}
+#endif /* TEST_CANON_HOST */