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') ||
64 bool hostname_is_valid(const char *s) {
71 /* Doesn't accept empty hostnames, hostnames with trailing or
72 * leading dots, and hostnames with multiple dots in a
73 * sequence. Also ensures that the length stays below
76 for (p = s, dot = true; *p; p++) {
83 if (!hostname_valid_char(*p))
93 if (p-s > HOST_NAME_MAX)
99 char* hostname_cleanup(char *s, bool lowercase) {
105 for (p = s, d = s, dot = true; *p; p++) {
112 } else if (hostname_valid_char(*p)) {
113 *(d++) = lowercase ? tolower(*p) : *p;
124 strshorten(s, HOST_NAME_MAX);
129 bool is_localhost(const char *hostname) {
132 /* This tries to identify local host and domain names
133 * described in RFC6761 plus the redhatism of .localdomain */
135 return streq(hostname, "localhost") ||
136 streq(hostname, "localhost.") ||
137 streq(hostname, "localdomain.") ||
138 streq(hostname, "localdomain") ||
139 endswith(hostname, ".localhost") ||
140 endswith(hostname, ".localhost.") ||
141 endswith(hostname, ".localdomain") ||
142 endswith(hostname, ".localdomain.");
145 int sethostname_idempotent(const char *s) {
146 char buf[HOST_NAME_MAX + 1] = {};
150 if (gethostname(buf, sizeof(buf)) < 0)
156 if (sethostname(s, strlen(s)) < 0)
162 int read_hostname_config(const char *path, char **hostname) {
163 _cleanup_fclose_ FILE *f = NULL;
170 f = fopen(path, "re");
174 /* may have comments, ignore them */
175 FOREACH_LINE(l, f, return -errno) {
177 if (l[0] != '\0' && l[0] != '#') {
178 /* found line with value */
179 name = hostname_cleanup(l, false);
188 /* no non-empty line found */