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e3bff60a MP |
1 | /*** |
2 | This file is part of systemd. | |
3 | ||
4 | Copyright 2015 Lennart Poettering | |
5 | ||
6 | systemd is free software; you can redistribute it and/or modify it | |
7 | under the terms of the GNU Lesser General Public License as published by | |
8 | the Free Software Foundation; either version 2.1 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | systemd is distributed in the hope that it will be useful, but | |
12 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public License | |
17 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
18 | ***/ | |
19 | ||
4c89c718 MP |
20 | #include <bits/local_lim.h> |
21 | #include <errno.h> | |
22 | #include <limits.h> | |
23 | #include <stdio.h> | |
24 | #include <string.h> | |
db2df898 | 25 | #include <sys/utsname.h> |
4c89c718 | 26 | #include <unistd.h> |
e3bff60a | 27 | |
db2df898 MP |
28 | #include "fd-util.h" |
29 | #include "fileio.h" | |
e3bff60a | 30 | #include "hostname-util.h" |
4c89c718 | 31 | #include "macro.h" |
db2df898 | 32 | #include "string-util.h" |
e3bff60a MP |
33 | |
34 | bool hostname_is_set(void) { | |
35 | struct utsname u; | |
36 | ||
37 | assert_se(uname(&u) >= 0); | |
38 | ||
39 | if (isempty(u.nodename)) | |
40 | return false; | |
41 | ||
42 | /* This is the built-in kernel default host name */ | |
43 | if (streq(u.nodename, "(none)")) | |
44 | return false; | |
45 | ||
46 | return true; | |
47 | } | |
48 | ||
49 | char* gethostname_malloc(void) { | |
50 | struct utsname u; | |
51 | ||
52 | assert_se(uname(&u) >= 0); | |
53 | ||
54 | if (isempty(u.nodename) || streq(u.nodename, "(none)")) | |
55 | return strdup(u.sysname); | |
56 | ||
57 | return strdup(u.nodename); | |
58 | } | |
59 | ||
60 | static bool hostname_valid_char(char c) { | |
61 | return | |
62 | (c >= 'a' && c <= 'z') || | |
63 | (c >= 'A' && c <= 'Z') || | |
64 | (c >= '0' && c <= '9') || | |
65 | c == '-' || | |
66 | c == '_' || | |
67 | c == '.'; | |
68 | } | |
69 | ||
13d276d0 MP |
70 | /** |
71 | * Check if s looks like a valid host name or FQDN. This does not do | |
72 | * full DNS validation, but only checks if the name is composed of | |
73 | * allowed characters and the length is not above the maximum allowed | |
74 | * by Linux (c.f. dns_name_is_valid()). Trailing dot is allowed if | |
75 | * allow_trailing_dot is true and at least two components are present | |
76 | * in the name. Note that due to the restricted charset and length | |
77 | * this call is substantially more conservative than | |
4c89c718 | 78 | * dns_name_is_valid(). |
13d276d0 MP |
79 | */ |
80 | bool hostname_is_valid(const char *s, bool allow_trailing_dot) { | |
81 | unsigned n_dots = 0; | |
e3bff60a MP |
82 | const char *p; |
83 | bool dot; | |
84 | ||
85 | if (isempty(s)) | |
86 | return false; | |
87 | ||
13d276d0 | 88 | /* Doesn't accept empty hostnames, hostnames with |
e3bff60a MP |
89 | * leading dots, and hostnames with multiple dots in a |
90 | * sequence. Also ensures that the length stays below | |
91 | * HOST_NAME_MAX. */ | |
92 | ||
93 | for (p = s, dot = true; *p; p++) { | |
94 | if (*p == '.') { | |
95 | if (dot) | |
96 | return false; | |
97 | ||
98 | dot = true; | |
13d276d0 | 99 | n_dots ++; |
e3bff60a MP |
100 | } else { |
101 | if (!hostname_valid_char(*p)) | |
102 | return false; | |
103 | ||
104 | dot = false; | |
105 | } | |
106 | } | |
107 | ||
13d276d0 | 108 | if (dot && (n_dots < 2 || !allow_trailing_dot)) |
e3bff60a MP |
109 | return false; |
110 | ||
13d276d0 MP |
111 | if (p-s > HOST_NAME_MAX) /* Note that HOST_NAME_MAX is 64 on |
112 | * Linux, but DNS allows domain names | |
113 | * up to 255 characters */ | |
e3bff60a MP |
114 | return false; |
115 | ||
116 | return true; | |
117 | } | |
118 | ||
13d276d0 | 119 | char* hostname_cleanup(char *s) { |
e3bff60a MP |
120 | char *p, *d; |
121 | bool dot; | |
122 | ||
123 | assert(s); | |
124 | ||
125 | for (p = s, d = s, dot = true; *p; p++) { | |
126 | if (*p == '.') { | |
127 | if (dot) | |
128 | continue; | |
129 | ||
130 | *(d++) = '.'; | |
131 | dot = true; | |
132 | } else if (hostname_valid_char(*p)) { | |
13d276d0 | 133 | *(d++) = *p; |
e3bff60a MP |
134 | dot = false; |
135 | } | |
136 | ||
137 | } | |
138 | ||
139 | if (dot && d > s) | |
140 | d[-1] = 0; | |
141 | else | |
142 | *d = 0; | |
143 | ||
144 | strshorten(s, HOST_NAME_MAX); | |
145 | ||
146 | return s; | |
147 | } | |
148 | ||
149 | bool is_localhost(const char *hostname) { | |
150 | assert(hostname); | |
151 | ||
152 | /* This tries to identify local host and domain names | |
153 | * described in RFC6761 plus the redhatism of .localdomain */ | |
154 | ||
13d276d0 MP |
155 | return strcaseeq(hostname, "localhost") || |
156 | strcaseeq(hostname, "localhost.") || | |
157 | strcaseeq(hostname, "localdomain.") || | |
158 | strcaseeq(hostname, "localdomain") || | |
159 | endswith_no_case(hostname, ".localhost") || | |
160 | endswith_no_case(hostname, ".localhost.") || | |
161 | endswith_no_case(hostname, ".localdomain") || | |
162 | endswith_no_case(hostname, ".localdomain."); | |
163 | } | |
164 | ||
165 | bool is_gateway_hostname(const char *hostname) { | |
166 | assert(hostname); | |
167 | ||
168 | /* This tries to identify the valid syntaxes for the our | |
169 | * synthetic "gateway" host. */ | |
170 | ||
171 | return | |
172 | strcaseeq(hostname, "gateway") || | |
173 | strcaseeq(hostname, "gateway."); | |
e3bff60a MP |
174 | } |
175 | ||
176 | int sethostname_idempotent(const char *s) { | |
177 | char buf[HOST_NAME_MAX + 1] = {}; | |
178 | ||
179 | assert(s); | |
180 | ||
181 | if (gethostname(buf, sizeof(buf)) < 0) | |
182 | return -errno; | |
183 | ||
184 | if (streq(buf, s)) | |
185 | return 0; | |
186 | ||
187 | if (sethostname(s, strlen(s)) < 0) | |
188 | return -errno; | |
189 | ||
190 | return 1; | |
191 | } | |
192 | ||
193 | int read_hostname_config(const char *path, char **hostname) { | |
194 | _cleanup_fclose_ FILE *f = NULL; | |
195 | char l[LINE_MAX]; | |
196 | char *name = NULL; | |
197 | ||
198 | assert(path); | |
199 | assert(hostname); | |
200 | ||
201 | f = fopen(path, "re"); | |
202 | if (!f) | |
203 | return -errno; | |
204 | ||
205 | /* may have comments, ignore them */ | |
206 | FOREACH_LINE(l, f, return -errno) { | |
207 | truncate_nl(l); | |
208 | if (l[0] != '\0' && l[0] != '#') { | |
209 | /* found line with value */ | |
13d276d0 | 210 | name = hostname_cleanup(l); |
e3bff60a MP |
211 | name = strdup(name); |
212 | if (!name) | |
213 | return -ENOMEM; | |
214 | break; | |
215 | } | |
216 | } | |
217 | ||
218 | if (!name) | |
219 | /* no non-empty line found */ | |
220 | return -ENOENT; | |
221 | ||
222 | *hostname = name; | |
223 | return 0; | |
224 | } |