1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
|
/* Copyright (C) 1995-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <alloca.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <netdb.h>
#include <not-cancel.h>
#include <stdbool.h>
#define HOSTIDFILE "/etc/hostid"
#ifdef SET_PROCEDURE
int
sethostid (long int id)
{
int fd;
ssize_t written;
int32_t id32 = id;
/* Test for appropriate rights to set host ID. */
if (__libc_enable_secure)
{
__set_errno (EPERM);
return -1;
}
/* Make sure the ID is not too large. Needed for bi-arch support. */
if (id32 != id)
{
__set_errno (EOVERFLOW);
return -1;
}
/* Open file for writing. Everybody is allowed to read this file. */
fd = __open_nocancel (HOSTIDFILE, O_CREAT|O_WRONLY|O_TRUNC, 0644);
if (fd < 0)
return -1;
written = __write_nocancel (fd, &id32, sizeof (id32));
__close_nocancel_nostatus (fd);
return written != sizeof (id32) ? -1 : 0;
}
#else
# include <string.h>
# include <sys/param.h>
# include <resolv/netdb.h>
# include <netinet/in.h>
# include <scratch_buffer.h>
long int
gethostid (void)
{
char hostname[MAXHOSTNAMELEN + 1];
struct hostent hostbuf, *hp;
int32_t id;
struct in_addr in;
int herr;
int fd;
/* First try to get the ID from a former invocation of sethostid. */
fd = __open_nocancel (HOSTIDFILE, O_RDONLY|O_LARGEFILE, 0);
if (fd >= 0)
{
ssize_t n = __read_nocancel (fd, &id, sizeof (id));
__close_nocancel_nostatus (fd);
if (n == sizeof (id))
return id;
}
/* Getting from the file was not successful. An intelligent guess
for a unique number of a host is its IP address. To get the IP
address we need to know the host name. */
if (__gethostname (hostname, MAXHOSTNAMELEN) < 0 || hostname[0] == '\0')
/* This also fails. Return and arbitrary value. */
return 0;
/* Determine the IP address of the host name. */
struct scratch_buffer tmpbuf;
scratch_buffer_init (&tmpbuf);
while (true)
{
int ret = __gethostbyname_r (hostname, &hostbuf,
tmpbuf.data, tmpbuf.length, &hp, &herr);
if (ret == 0 && hp != NULL)
break;
else
{
/* Enlarge the buffer on ERANGE. */
if (ret != 0 && herr == NETDB_INTERNAL && errno == ERANGE)
{
if (!scratch_buffer_grow (&tmpbuf))
return 0;
}
/* Other errors are a failure. Return an arbitrary value. */
else
{
scratch_buffer_free (&tmpbuf);
return 0;
}
}
}
in.s_addr = 0;
memcpy (&in, hp->h_addr,
(int) sizeof (in) < hp->h_length ? (int) sizeof (in) : hp->h_length);
scratch_buffer_free (&tmpbuf);
/* For the return value to be not exactly the IP address we do some
bit fiddling. */
return (int32_t) (in.s_addr << 16 | in.s_addr >> 16);
}
#endif
|
