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