mirror of
https://github.com/coreutils/coreutils.git
synced 2024-12-12 11:23:43 +08:00
126 lines
3.2 KiB
C
126 lines
3.2 KiB
C
/* Host name canonicalization
|
|
|
|
Copyright (C) 1995, 1999, 2000, 2002, 2003, 2004, 2005 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
|
|
|
|
#ifdef HAVE_CONFIG_H
|
|
# include <config.h>
|
|
#endif
|
|
|
|
#include <sys/types.h>
|
|
#include <unistd.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#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
|
|
|
|
#include "strdup.h"
|
|
|
|
/* Returns the canonical hostname associated with HOST (allocated in a static
|
|
buffer), or NULL if it can't be determined. */
|
|
char *
|
|
canon_host (char const *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)
|
|
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++)
|
|
{
|
|
char *s = canon_host (argv[i]);
|
|
printf ("%s: %s\n", argv[i], (s ? s : "<undef>"));
|
|
}
|
|
exit (0);
|
|
}
|
|
#endif /* TEST_CANON_HOST */
|