summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJim Meyering <jim@meyering.net>1996-02-04 12:47:33 +0000
committerJim Meyering <jim@meyering.net>1996-02-04 12:47:33 +0000
commit2d882a72007b918bd51076d72424fb9cd3b78c59 (patch)
treeb36bd9c03561ea958da745cae483896bf3cf4d24
parentd2a3720ad06d950f30272ce30600d0ccea5d0f22 (diff)
downloadcoreutils-2d882a72007b918bd51076d72424fb9cd3b78c59.tar.xz
.
-rw-r--r--lib/canon-host.c79
1 files changed, 79 insertions, 0 deletions
diff --git a/lib/canon-host.c b/lib/canon-host.c
new file mode 100644
index 000000000..180c86a07
--- /dev/null
+++ b/lib/canon-host.c
@@ -0,0 +1,79 @@
+/* Host name canonicalization
+
+ Copyright (C) 1995 Free Software Foundation, Inc.
+
+ Written by Miles Bader <miles@gnu.ai.mit.edu>
+
+ This program is free software; you can redistribute it and/or
+ modify it under the terms of the GNU General Public License as
+ published by the Free Software Foundation; either version 2, or (at
+ your option) any later version.
+
+ This program is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ 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. */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#ifdef HAVE_STRING_H
+#include <string.h>
+#endif
+#ifdef HAVE_NETDB_H
+#include <netdb.h>
+#endif
+
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+#ifdef HAVE_ARPA_INET_H
+#include <arpa/inet.h>
+#endif
+
+/* Returns the canonical hostname associated with HOST (allocated in a static
+ buffer), or 0 if it can't be determined. */
+char *
+canon_host (host)
+ char *host;
+{
+#ifdef HAVE_GETHOSTBYNAME
+ struct hostent *he = gethostbyname (host);
+
+ if (he)
+ {
+#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 he->h_name;
+ }
+
+#else /* ! HAVE_GETHOSTBYNAME */
+ return 0;
+#endif /* HAVE_GETHOSTBYNAME */
+}