X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=lib%2Fcanon-host.c;h=dd1f88b0b4ffb622b4ea43022c22467fdedfd904;hb=118ba24d049832db7affcd30bed4209cb37b2b30;hp=f302f5736cef675bd9dca2e59495a00d2edb4a4b;hpb=96d1a464b72f0e9851984f901eaf2c456c5561fd;p=gnulib.git

diff --git a/lib/canon-host.c b/lib/canon-host.c
index f302f5736..dd1f88b0b 100644
--- a/lib/canon-host.c
+++ b/lib/canon-host.c
@@ -1,6 +1,7 @@
 /* Host name canonicalization
 
-   Copyright (C) 1995 Free Software Foundation, Inc.
+   Copyright (C) 1995, 1999, 2000, 2002, 2003, 2004 Free Software
+   Foundation, Inc.
 
    Written by Miles Bader <miles@gnu.ai.mit.edu>
 
@@ -15,63 +16,112 @@
    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 */