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/*
* Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
*
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
#define __FORCE_GLIBC
#include <features.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/param.h>
#include <netinet/in.h>
#include <netdb.h>
#include <fcntl.h>
#include <unistd.h>
#include <not-cancel.h>
#define HOSTID "/etc/hostid"
#ifdef __USE_BSD
int sethostid(long int new_id)
{
int fd;
int ret;
if (geteuid() || getuid())
return __set_errno(EPERM);
fd = open_not_cancel(HOSTID, O_CREAT|O_WRONLY, 0644);
if (fd < 0)
return fd;
ret = write_not_cancel(fd, &new_id, sizeof(new_id)) == sizeof(new_id) ? 0 : -1;
close_not_cancel_no_status (fd);
return ret;
}
#endif
long int gethostid(void)
{
char host[MAXHOSTNAMELEN + 1];
int fd, id;
/* If hostid was already set then we can return that value.
* It is not an error if we cannot read this file. It is not even an
* error if we cannot read all the bytes, we just carry on trying...
*/
fd = open_not_cancel_2(HOSTID, O_RDONLY);
if (fd >= 0 && read_not_cancel(fd, &id, sizeof(id)))
{
close_not_cancel_no_status (fd);
return id;
}
if (fd >= 0) close_not_cancel_no_status (fd);
/* Try some methods of returning a unique 32 bit id. Clearly IP
* numbers, if on the internet, will have a unique address. If they
* are not on the internet then we can return 0 which means they should
* really set this number via a sethostid() call. If their hostname
* returns the loopback number (i.e. if they have put their hostname
* in the /etc/hosts file with 127.0.0.1) then all such hosts will
* have a non-unique hostid, but it doesn't matter anyway and
* gethostid() will return a non zero number without the need for
* setting one anyway.
* Mitch
*/
if (gethostname(host, MAXHOSTNAMELEN) >= 0 && *host) {
struct hostent *hp;
struct in_addr in;
struct hostent ghbn_h;
char ghbn_buf[sizeof(struct in_addr) +
sizeof(struct in_addr *)*2 +
sizeof(char *)*((2 + 5/*MAX_ALIASES*/ +
1)/*ALIAS_DIM*/) +
256/*namebuffer*/ + 32/* margin */];
int ghbn_errno;
/* replace gethostbyname() with gethostbyname_r() - ron@zing.net */
/*if ((hp = gethostbyname(host)) == (struct hostent *)NULL)*/
gethostbyname_r(host, &ghbn_h, ghbn_buf, sizeof(ghbn_buf), &hp, &ghbn_errno);
if (hp == NULL) {
/* This is not a error if we get here, as all it means is that
* this host is not on a network and/or they have not
* configured their network properly. So we return the unset
* hostid which should be 0, meaning that they should set it !!
*/
return 0;
}
memcpy(&in, hp->h_addr, hp->h_length);
/* Just so it doesn't look exactly like the IP addr */
return (in.s_addr<<16 | in.s_addr>>16);
}
return 0;
}
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