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git.ipfire.org Git - thirdparty/systemd.git/blob - src/basic/hostname-util.c
1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2015 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
22 #include <sys/utsname.h>
26 #include "hostname-util.h"
28 bool hostname_is_set(void) {
31 assert_se(uname(&u
) >= 0);
33 if (isempty(u
.nodename
))
36 /* This is the built-in kernel default host name */
37 if (streq(u
.nodename
, "(none)"))
43 char* gethostname_malloc(void) {
46 assert_se(uname(&u
) >= 0);
48 if (isempty(u
.nodename
) || streq(u
.nodename
, "(none)"))
49 return strdup(u
.sysname
);
51 return strdup(u
.nodename
);
54 static bool hostname_valid_char(char c
) {
56 (c
>= 'a' && c
<= 'z') ||
57 (c
>= 'A' && c
<= 'Z') ||
58 (c
>= '0' && c
<= '9') ||
65 * Check if s looks like a valid host name or FQDN. This does not do
66 * full DNS validation, but only checks if the name is composed of
67 * allowed characters and the length is not above the maximum allowed
68 * by Linux (c.f. dns_name_is_valid()). Trailing dot is allowed if
69 * allow_trailing_dot is true and at least two components are present
70 * in the name. Note that due to the restricted charset and length
71 * this call is substantially more conservative than
72 * dns_domain_is_valid().
74 bool hostname_is_valid(const char *s
, bool allow_trailing_dot
) {
82 /* Doesn't accept empty hostnames, hostnames with
83 * leading dots, and hostnames with multiple dots in a
84 * sequence. Also ensures that the length stays below
87 for (p
= s
, dot
= true; *p
; p
++) {
95 if (!hostname_valid_char(*p
))
102 if (dot
&& (n_dots
< 2 || !allow_trailing_dot
))
105 if (p
-s
> HOST_NAME_MAX
) /* Note that HOST_NAME_MAX is 64 on
106 * Linux, but DNS allows domain names
107 * up to 255 characters */
113 char* hostname_cleanup(char *s
) {
119 for (p
= s
, d
= s
, dot
= true; *p
; p
++) {
126 } else if (hostname_valid_char(*p
)) {
138 strshorten(s
, HOST_NAME_MAX
);
143 bool is_localhost(const char *hostname
) {
146 /* This tries to identify local host and domain names
147 * described in RFC6761 plus the redhatism of .localdomain */
149 return strcaseeq(hostname
, "localhost") ||
150 strcaseeq(hostname
, "localhost.") ||
151 strcaseeq(hostname
, "localdomain.") ||
152 strcaseeq(hostname
, "localdomain") ||
153 endswith_no_case(hostname
, ".localhost") ||
154 endswith_no_case(hostname
, ".localhost.") ||
155 endswith_no_case(hostname
, ".localdomain") ||
156 endswith_no_case(hostname
, ".localdomain.");
159 bool is_gateway_hostname(const char *hostname
) {
162 /* This tries to identify the valid syntaxes for the our
163 * synthetic "gateway" host. */
166 strcaseeq(hostname
, "gateway") ||
167 strcaseeq(hostname
, "gateway.");
170 int sethostname_idempotent(const char *s
) {
171 char buf
[HOST_NAME_MAX
+ 1] = {};
175 if (gethostname(buf
, sizeof(buf
)) < 0)
181 if (sethostname(s
, strlen(s
)) < 0)
187 int read_hostname_config(const char *path
, char **hostname
) {
188 _cleanup_fclose_
FILE *f
= NULL
;
195 f
= fopen(path
, "re");
199 /* may have comments, ignore them */
200 FOREACH_LINE(l
, f
, return -errno
) {
202 if (l
[0] != '\0' && l
[0] != '#') {
203 /* found line with value */
204 name
= hostname_cleanup(l
);
213 /* no non-empty line found */