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958b66ea LP |
1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2015 Lennart Poettering | |
7 | ||
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. | |
12 | ||
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. | |
17 | ||
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/>. | |
20 | ***/ | |
21 | ||
958b66ea | 22 | #include <ctype.h> |
07630cea | 23 | #include <sys/utsname.h> |
958b66ea | 24 | |
3ffd4af2 | 25 | #include "fd-util.h" |
0d39fa9c | 26 | #include "fileio.h" |
3ffd4af2 | 27 | #include "hostname-util.h" |
07630cea | 28 | #include "string-util.h" |
958b66ea | 29 | #include "util.h" |
958b66ea LP |
30 | |
31 | bool hostname_is_set(void) { | |
32 | struct utsname u; | |
33 | ||
34 | assert_se(uname(&u) >= 0); | |
35 | ||
36 | if (isempty(u.nodename)) | |
37 | return false; | |
38 | ||
39 | /* This is the built-in kernel default host name */ | |
40 | if (streq(u.nodename, "(none)")) | |
41 | return false; | |
42 | ||
43 | return true; | |
44 | } | |
45 | ||
46 | char* gethostname_malloc(void) { | |
47 | struct utsname u; | |
48 | ||
49 | assert_se(uname(&u) >= 0); | |
50 | ||
51 | if (isempty(u.nodename) || streq(u.nodename, "(none)")) | |
52 | return strdup(u.sysname); | |
53 | ||
54 | return strdup(u.nodename); | |
55 | } | |
56 | ||
57 | static bool hostname_valid_char(char c) { | |
58 | return | |
59 | (c >= 'a' && c <= 'z') || | |
60 | (c >= 'A' && c <= 'Z') || | |
61 | (c >= '0' && c <= '9') || | |
62 | c == '-' || | |
63 | c == '_' || | |
64 | c == '.'; | |
65 | } | |
66 | ||
8fb49443 | 67 | /** |
b59abc4d | 68 | * Check if s looks like a valid host name or FQDN. This does not do |
8fb49443 ZJS |
69 | * full DNS validation, but only checks if the name is composed of |
70 | * allowed characters and the length is not above the maximum allowed | |
71 | * by Linux (c.f. dns_name_is_valid()). Trailing dot is allowed if | |
b59abc4d LP |
72 | * allow_trailing_dot is true and at least two components are present |
73 | * in the name. Note that due to the restricted charset and length | |
74 | * this call is substantially more conservative than | |
75 | * dns_domain_is_valid(). | |
8fb49443 | 76 | */ |
b59abc4d LP |
77 | bool hostname_is_valid(const char *s, bool allow_trailing_dot) { |
78 | unsigned n_dots = 0; | |
958b66ea LP |
79 | const char *p; |
80 | bool dot; | |
81 | ||
82 | if (isempty(s)) | |
83 | return false; | |
84 | ||
8fb49443 | 85 | /* Doesn't accept empty hostnames, hostnames with |
958b66ea LP |
86 | * leading dots, and hostnames with multiple dots in a |
87 | * sequence. Also ensures that the length stays below | |
88 | * HOST_NAME_MAX. */ | |
89 | ||
90 | for (p = s, dot = true; *p; p++) { | |
91 | if (*p == '.') { | |
92 | if (dot) | |
93 | return false; | |
94 | ||
95 | dot = true; | |
b59abc4d | 96 | n_dots ++; |
958b66ea LP |
97 | } else { |
98 | if (!hostname_valid_char(*p)) | |
99 | return false; | |
100 | ||
101 | dot = false; | |
102 | } | |
103 | } | |
104 | ||
b59abc4d | 105 | if (dot && (n_dots < 2 || !allow_trailing_dot)) |
958b66ea LP |
106 | return false; |
107 | ||
b59abc4d LP |
108 | if (p-s > HOST_NAME_MAX) /* Note that HOST_NAME_MAX is 64 on |
109 | * Linux, but DNS allows domain names | |
110 | * up to 255 characters */ | |
958b66ea LP |
111 | return false; |
112 | ||
113 | return true; | |
114 | } | |
115 | ||
ae691c1d | 116 | char* hostname_cleanup(char *s) { |
958b66ea LP |
117 | char *p, *d; |
118 | bool dot; | |
119 | ||
120 | assert(s); | |
121 | ||
122 | for (p = s, d = s, dot = true; *p; p++) { | |
123 | if (*p == '.') { | |
124 | if (dot) | |
125 | continue; | |
126 | ||
127 | *(d++) = '.'; | |
128 | dot = true; | |
129 | } else if (hostname_valid_char(*p)) { | |
ae691c1d | 130 | *(d++) = *p; |
958b66ea LP |
131 | dot = false; |
132 | } | |
133 | ||
134 | } | |
135 | ||
136 | if (dot && d > s) | |
137 | d[-1] = 0; | |
138 | else | |
139 | *d = 0; | |
140 | ||
141 | strshorten(s, HOST_NAME_MAX); | |
142 | ||
143 | return s; | |
144 | } | |
145 | ||
146 | bool is_localhost(const char *hostname) { | |
147 | assert(hostname); | |
148 | ||
149 | /* This tries to identify local host and domain names | |
150 | * described in RFC6761 plus the redhatism of .localdomain */ | |
151 | ||
90365b04 ZJS |
152 | return strcaseeq(hostname, "localhost") || |
153 | strcaseeq(hostname, "localhost.") || | |
154 | strcaseeq(hostname, "localdomain.") || | |
155 | strcaseeq(hostname, "localdomain") || | |
156 | endswith_no_case(hostname, ".localhost") || | |
157 | endswith_no_case(hostname, ".localhost.") || | |
158 | endswith_no_case(hostname, ".localdomain") || | |
159 | endswith_no_case(hostname, ".localdomain."); | |
958b66ea LP |
160 | } |
161 | ||
46a5e0e7 LP |
162 | bool is_gateway_hostname(const char *hostname) { |
163 | assert(hostname); | |
164 | ||
165 | /* This tries to identify the valid syntaxes for the our | |
166 | * synthetic "gateway" host. */ | |
167 | ||
168 | return | |
169 | strcaseeq(hostname, "gateway") || | |
170 | strcaseeq(hostname, "gateway."); | |
171 | } | |
172 | ||
958b66ea LP |
173 | int sethostname_idempotent(const char *s) { |
174 | char buf[HOST_NAME_MAX + 1] = {}; | |
175 | ||
176 | assert(s); | |
177 | ||
178 | if (gethostname(buf, sizeof(buf)) < 0) | |
179 | return -errno; | |
180 | ||
181 | if (streq(buf, s)) | |
182 | return 0; | |
183 | ||
184 | if (sethostname(s, strlen(s)) < 0) | |
185 | return -errno; | |
186 | ||
187 | return 1; | |
188 | } | |
139e5336 MP |
189 | |
190 | int read_hostname_config(const char *path, char **hostname) { | |
191 | _cleanup_fclose_ FILE *f = NULL; | |
192 | char l[LINE_MAX]; | |
193 | char *name = NULL; | |
194 | ||
195 | assert(path); | |
196 | assert(hostname); | |
197 | ||
198 | f = fopen(path, "re"); | |
199 | if (!f) | |
200 | return -errno; | |
201 | ||
202 | /* may have comments, ignore them */ | |
203 | FOREACH_LINE(l, f, return -errno) { | |
204 | truncate_nl(l); | |
205 | if (l[0] != '\0' && l[0] != '#') { | |
206 | /* found line with value */ | |
ae691c1d | 207 | name = hostname_cleanup(l); |
139e5336 MP |
208 | name = strdup(name); |
209 | if (!name) | |
210 | return -ENOMEM; | |
211 | break; | |
212 | } | |
213 | } | |
214 | ||
215 | if (!name) | |
216 | /* no non-empty line found */ | |
217 | return -ENOENT; | |
218 | ||
219 | *hostname = name; | |
220 | return 0; | |
221 | } |