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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.
*/
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.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
#define _addr(a) (((struct sockaddr_in*)a->ai_addr)->sin_addr.s_addr)
long int gethostid(void)
{
char host[HOST_NAME_MAX + 1];
int fd, id = 0;
/* 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) {
int i = read_not_cancel(fd, &id, sizeof(id));
close_not_cancel_no_status(fd);
if (i > 0)
return id;
}
/* 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, HOST_NAME_MAX) >= 0 && *host) {
struct addrinfo hints = {.ai_family = AF_INET}, *results, *addr;
if (!getaddrinfo(host, NULL, &hints, &results)) {
for (addr = results; addr; addr = results->ai_next) {
/* Just so it doesn't look exactly like the
IP addr */
id = _addr(addr) << 16 | _addr(addr) >> 16;
break;
}
freeaddrinfo(results);
}
}
return id;
}
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