/* Host name canonicalization
- Copyright (C) 1995 Free Software Foundation, Inc.
+ Copyright (C) 2005-2014 Free Software Foundation, Inc.
- Written by Miles Bader <miles@gnu.ai.mit.edu>
+ Written by Derek Price <derek@ximbiot.com>.
- 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 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 3, 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.
+ 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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_SYS_SOCKET_H
-# include <sys/socket.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. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+#include "canon-host.h"
+
+#include <string.h>
+#include <netdb.h>
+
+/* Store the last error for the single-threaded version of this function. */
+static int last_cherror;
+
+/* Single-threaded of wrapper for canon_host_r. After a NULL return, error
+ messages may be retrieved via ch_strerror(). */
char *
-canon_host (host)
- char *host;
+canon_host (const char *host)
{
-#ifdef HAVE_GETHOSTBYNAME
- struct hostent *he = gethostbyname (host);
+ return canon_host_r (host, &last_cherror);
+}
+
+/* Return a malloc'd string containing the canonical hostname associated with
+ HOST, or NULL if a canonical name cannot be determined. On NULL return,
+ if CHERROR is not NULL, set *CHERROR to an error code as returned by
+ getaddrinfo(). Use ch_strerror_r() or gai_strerror() to convert a *CHERROR
+ value to a string suitable for error messages.
+
+ WARNINGS
+ HOST must be a string representation of a resolvable name for this host.
+ Strings containing an IP address in dotted decimal notation will be
+ returned as-is, without further resolution.
- if (he)
+ The use of the word "canonical" in this context is unfortunate but
+ entrenched. The value returned by this function will be the end result
+ of the resolution of any CNAME chains in the DNS. There may only be one
+ such value for any given hostname, though the actual IP address
+ referenced by this value and the device using that IP address may each
+ actually have any number of such "canonical" hostnames. See the POSIX
+ getaddrinfo spec <http://www.opengroup.org/susv3xsh/getaddrinfo.html">,
+ RFC 1034 <http://www.faqs.org/rfcs/rfc1034.html>, & RFC 2181
+ <http://www.faqs.org/rfcs/rfc2181.html> for more on what this confusing
+ term really refers to. */
+char *
+canon_host_r (char const *host, int *cherror)
+{
+ char *retval = NULL;
+ static struct addrinfo hints;
+ struct addrinfo *res = NULL;
+ int status;
+
+ hints.ai_flags = AI_CANONNAME;
+ status = getaddrinfo (host, NULL, &hints, &res);
+ if (!status)
{
-# 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);
+ /* http://lists.gnu.org/archive/html/bug-coreutils/2006-09/msg00300.html
+ says Darwin 7.9.0 getaddrinfo returns 0 but sets
+ res->ai_canonname to NULL. */
+ retval = strdup (res->ai_canonname ? res->ai_canonname : host);
+ if (!retval && cherror)
+ *cherror = EAI_MEMORY;
+ freeaddrinfo (res);
}
-#endif /* HAVE_GETHOSTBYNAME */
- return 0;
+ else if (cherror)
+ *cherror = status;
+
+ return retval;
+}
+
+/* Return a string describing the last error encountered by canon_host. */
+const char *
+ch_strerror (void)
+{
+ return gai_strerror (last_cherror);
}
projects / gnulib.git / blobdiff