106 lines
2.5 KiB
C
Executable File
106 lines
2.5 KiB
C
Executable File
/* A slightly more convenient wrapper for gethostname
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Copyright (C) 1996, 1997, 2000 Free Software Foundation, Inc.
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Written by Miles Bader <miles@gnu.ai.mit.edu>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2, or (at
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your option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <unistd.h>
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#ifdef HAVE_MALLOC_H
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#include <malloc.h>
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#endif
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#if defined(STDC_HEADERS) || defined(HAVE_STDLIB_H)
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#include <stdlib.h>
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#endif
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#include <string.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netdb.h>
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#if __STDC__
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# define VOID void
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#else
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# define VOID char
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#endif
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extern VOID *xrealloc __P((VOID *p, size_t n));
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/* Return the name of the localhost. This is just a wrapper for gethostname,
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which takes care of allocating a big enough buffer, and caches the result
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after the first call (so the result should be copied before modification).
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If something goes wrong, 0 is returned, and errno set. */
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/* We know longer use static buffers, is to dangerous and
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cause subtile bugs. */
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char *
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localhost (void)
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{
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char *buf = NULL;
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size_t buf_len = 0;
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int status = 0;
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do
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{
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char *tmp;
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errno = 0;
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buf_len += 256; /* Initial guess */
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tmp = xrealloc (buf, buf_len);
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if (tmp == NULL)
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{
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errno = ENOMEM;
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free (buf);
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return 0;
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}
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else
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buf = tmp;
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} while (((status = gethostname(buf, buf_len)) == 0 && !memchr (buf, '\0', buf_len))
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#ifdef ENAMETOOLONG
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|| errno == ENAMETOOLONG
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#endif
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);
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if (status != 0 && errno != 0)
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/* gethostname failed, abort. */
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{
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free (buf);
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buf = 0;
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}
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/* Determine FQDN */
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{
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struct hostent *hp = gethostbyname(buf);
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if (hp)
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{
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struct in_addr addr;
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addr.s_addr = *(unsigned int*) hp->h_addr;
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hp = gethostbyaddr((char *) &addr, sizeof(addr), AF_INET);
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if (hp)
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{
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free(buf);
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buf = strdup(hp->h_name);
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}
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}
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}
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return buf;
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}
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