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
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
|
/***
This file is part of systemd.
Copyright 2015 Lennart Poettering
systemd 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.
systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <bits/local_lim.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>
#include <sys/utsname.h>
#include <unistd.h>
#include "fd-util.h"
#include "fileio.h"
#include "hostname-util.h"
#include "macro.h"
#include "string-util.h"
bool hostname_is_set(void) {
struct utsname u;
assert_se(uname(&u) >= 0);
if (isempty(u.nodename))
return false;
/* This is the built-in kernel default host name */
if (streq(u.nodename, "(none)"))
return false;
return true;
}
char* gethostname_malloc(void) {
struct utsname u;
assert_se(uname(&u) >= 0);
if (isempty(u.nodename) || streq(u.nodename, "(none)"))
return strdup(u.sysname);
return strdup(u.nodename);
}
static bool hostname_valid_char(char c) {
return
(c >= 'a' && c <= 'z') ||
(c >= 'A' && c <= 'Z') ||
(c >= '0' && c <= '9') ||
c == '-' ||
c == '_' ||
c == '.';
}
/**
* Check if s looks like a valid host name or FQDN. This does not do
* full DNS validation, but only checks if the name is composed of
* allowed characters and the length is not above the maximum allowed
* by Linux (c.f. dns_name_is_valid()). Trailing dot is allowed if
* allow_trailing_dot is true and at least two components are present
* in the name. Note that due to the restricted charset and length
* this call is substantially more conservative than
* dns_name_is_valid().
*/
bool hostname_is_valid(const char *s, bool allow_trailing_dot) {
unsigned n_dots = 0;
const char *p;
bool dot;
if (isempty(s))
return false;
/* Doesn't accept empty hostnames, hostnames with
* leading dots, and hostnames with multiple dots in a
* sequence. Also ensures that the length stays below
* HOST_NAME_MAX. */
for (p = s, dot = true; *p; p++) {
if (*p == '.') {
if (dot)
return false;
dot = true;
n_dots ++;
} else {
if (!hostname_valid_char(*p))
return false;
dot = false;
}
}
if (dot && (n_dots < 2 || !allow_trailing_dot))
return false;
if (p-s > HOST_NAME_MAX) /* Note that HOST_NAME_MAX is 64 on
* Linux, but DNS allows domain names
* up to 255 characters */
return false;
return true;
}
char* hostname_cleanup(char *s) {
char *p, *d;
bool dot;
assert(s);
for (p = s, d = s, dot = true; *p; p++) {
if (*p == '.') {
if (dot)
continue;
*(d++) = '.';
dot = true;
} else if (hostname_valid_char(*p)) {
*(d++) = *p;
dot = false;
}
}
if (dot && d > s)
d[-1] = 0;
else
*d = 0;
strshorten(s, HOST_NAME_MAX);
return s;
}
bool is_localhost(const char *hostname) {
assert(hostname);
/* This tries to identify local host and domain names
* described in RFC6761 plus the redhatism of localdomain */
return strcaseeq(hostname, "localhost") ||
strcaseeq(hostname, "localhost.") ||
strcaseeq(hostname, "localhost.localdomain") ||
strcaseeq(hostname, "localhost.localdomain.") ||
endswith_no_case(hostname, ".localhost") ||
endswith_no_case(hostname, ".localhost.") ||
endswith_no_case(hostname, ".localhost.localdomain") ||
endswith_no_case(hostname, ".localhost.localdomain.");
}
bool is_gateway_hostname(const char *hostname) {
assert(hostname);
/* This tries to identify the valid syntaxes for the our
* synthetic "gateway" host. */
return
strcaseeq(hostname, "gateway") ||
strcaseeq(hostname, "gateway.");
}
int sethostname_idempotent(const char *s) {
char buf[HOST_NAME_MAX + 1] = {};
assert(s);
if (gethostname(buf, sizeof(buf)) < 0)
return -errno;
if (streq(buf, s))
return 0;
if (sethostname(s, strlen(s)) < 0)
return -errno;
return 1;
}
int read_hostname_config(const char *path, char **hostname) {
_cleanup_fclose_ FILE *f = NULL;
char l[LINE_MAX];
char *name = NULL;
assert(path);
assert(hostname);
f = fopen(path, "re");
if (!f)
return -errno;
/* may have comments, ignore them */
FOREACH_LINE(l, f, return -errno) {
truncate_nl(l);
if (l[0] != '\0' && l[0] != '#') {
/* found line with value */
name = hostname_cleanup(l);
name = strdup(name);
if (!name)
return -ENOMEM;
break;
}
}
if (!name)
/* no non-empty line found */
return -ENOENT;
*hostname = name;
return 0;
}
|
