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Commit | Line | Data |
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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
958b66ea LP |
2 | /*** |
3 | This file is part of systemd. | |
4 | ||
5 | Copyright 2015 Lennart Poettering | |
958b66ea LP |
6 | ***/ |
7 | ||
11c3a366 TA |
8 | #include <errno.h> |
9 | #include <limits.h> | |
10 | #include <stdio.h> | |
11 | #include <string.h> | |
07630cea | 12 | #include <sys/utsname.h> |
11c3a366 | 13 | #include <unistd.h> |
958b66ea | 14 | |
f35cb39e LP |
15 | #include "alloc-util.h" |
16 | #include "def.h" | |
3ffd4af2 | 17 | #include "fd-util.h" |
0d39fa9c | 18 | #include "fileio.h" |
3ffd4af2 | 19 | #include "hostname-util.h" |
11c3a366 | 20 | #include "macro.h" |
07630cea | 21 | #include "string-util.h" |
958b66ea LP |
22 | |
23 | bool hostname_is_set(void) { | |
24 | struct utsname u; | |
25 | ||
26 | assert_se(uname(&u) >= 0); | |
27 | ||
28 | if (isempty(u.nodename)) | |
29 | return false; | |
30 | ||
31 | /* This is the built-in kernel default host name */ | |
32 | if (streq(u.nodename, "(none)")) | |
33 | return false; | |
34 | ||
35 | return true; | |
36 | } | |
37 | ||
38 | char* gethostname_malloc(void) { | |
39 | struct utsname u; | |
40 | ||
953d28cc ZJS |
41 | /* This call tries to return something useful, either the actual hostname |
42 | * or it makes something up. The only reason it might fail is OOM. | |
43 | * It might even return "localhost" if that's set. */ | |
8e1ad1ea | 44 | |
958b66ea LP |
45 | assert_se(uname(&u) >= 0); |
46 | ||
47 | if (isempty(u.nodename) || streq(u.nodename, "(none)")) | |
d91e8e1b | 48 | return strdup(FALLBACK_HOSTNAME); |
958b66ea LP |
49 | |
50 | return strdup(u.nodename); | |
51 | } | |
52 | ||
8e1ad1ea LP |
53 | int gethostname_strict(char **ret) { |
54 | struct utsname u; | |
55 | char *k; | |
56 | ||
57 | /* This call will rather fail than make up a name. It will not return "localhost" either. */ | |
58 | ||
59 | assert_se(uname(&u) >= 0); | |
60 | ||
61 | if (isempty(u.nodename)) | |
62 | return -ENXIO; | |
63 | ||
64 | if (streq(u.nodename, "(none)")) | |
65 | return -ENXIO; | |
66 | ||
67 | if (is_localhost(u.nodename)) | |
68 | return -ENXIO; | |
69 | ||
70 | k = strdup(u.nodename); | |
71 | if (!k) | |
72 | return -ENOMEM; | |
73 | ||
74 | *ret = k; | |
75 | return 0; | |
76 | } | |
77 | ||
958b66ea LP |
78 | static bool hostname_valid_char(char c) { |
79 | return | |
80 | (c >= 'a' && c <= 'z') || | |
81 | (c >= 'A' && c <= 'Z') || | |
82 | (c >= '0' && c <= '9') || | |
4c701096 | 83 | IN_SET(c, '-', '_', '.'); |
958b66ea LP |
84 | } |
85 | ||
8fb49443 | 86 | /** |
b59abc4d | 87 | * Check if s looks like a valid host name or FQDN. This does not do |
8fb49443 ZJS |
88 | * full DNS validation, but only checks if the name is composed of |
89 | * allowed characters and the length is not above the maximum allowed | |
90 | * by Linux (c.f. dns_name_is_valid()). Trailing dot is allowed if | |
b59abc4d LP |
91 | * allow_trailing_dot is true and at least two components are present |
92 | * in the name. Note that due to the restricted charset and length | |
93 | * this call is substantially more conservative than | |
06d91ad7 | 94 | * dns_name_is_valid(). |
8fb49443 | 95 | */ |
b59abc4d LP |
96 | bool hostname_is_valid(const char *s, bool allow_trailing_dot) { |
97 | unsigned n_dots = 0; | |
958b66ea LP |
98 | const char *p; |
99 | bool dot; | |
100 | ||
101 | if (isempty(s)) | |
102 | return false; | |
103 | ||
8fb49443 | 104 | /* Doesn't accept empty hostnames, hostnames with |
958b66ea LP |
105 | * leading dots, and hostnames with multiple dots in a |
106 | * sequence. Also ensures that the length stays below | |
107 | * HOST_NAME_MAX. */ | |
108 | ||
109 | for (p = s, dot = true; *p; p++) { | |
110 | if (*p == '.') { | |
111 | if (dot) | |
112 | return false; | |
113 | ||
114 | dot = true; | |
313cefa1 | 115 | n_dots++; |
958b66ea LP |
116 | } else { |
117 | if (!hostname_valid_char(*p)) | |
118 | return false; | |
119 | ||
120 | dot = false; | |
121 | } | |
122 | } | |
123 | ||
b59abc4d | 124 | if (dot && (n_dots < 2 || !allow_trailing_dot)) |
958b66ea LP |
125 | return false; |
126 | ||
b59abc4d LP |
127 | if (p-s > HOST_NAME_MAX) /* Note that HOST_NAME_MAX is 64 on |
128 | * Linux, but DNS allows domain names | |
129 | * up to 255 characters */ | |
958b66ea LP |
130 | return false; |
131 | ||
132 | return true; | |
133 | } | |
134 | ||
ae691c1d | 135 | char* hostname_cleanup(char *s) { |
958b66ea LP |
136 | char *p, *d; |
137 | bool dot; | |
138 | ||
139 | assert(s); | |
140 | ||
46e1a227 TB |
141 | strshorten(s, HOST_NAME_MAX); |
142 | ||
958b66ea LP |
143 | for (p = s, d = s, dot = true; *p; p++) { |
144 | if (*p == '.') { | |
145 | if (dot) | |
146 | continue; | |
147 | ||
148 | *(d++) = '.'; | |
149 | dot = true; | |
150 | } else if (hostname_valid_char(*p)) { | |
ae691c1d | 151 | *(d++) = *p; |
958b66ea LP |
152 | dot = false; |
153 | } | |
958b66ea LP |
154 | } |
155 | ||
156 | if (dot && d > s) | |
157 | d[-1] = 0; | |
158 | else | |
159 | *d = 0; | |
160 | ||
958b66ea LP |
161 | return s; |
162 | } | |
163 | ||
164 | bool is_localhost(const char *hostname) { | |
165 | assert(hostname); | |
166 | ||
167 | /* This tries to identify local host and domain names | |
63003524 | 168 | * described in RFC6761 plus the redhatism of localdomain */ |
958b66ea | 169 | |
90365b04 ZJS |
170 | return strcaseeq(hostname, "localhost") || |
171 | strcaseeq(hostname, "localhost.") || | |
63003524 DH |
172 | strcaseeq(hostname, "localhost.localdomain") || |
173 | strcaseeq(hostname, "localhost.localdomain.") || | |
90365b04 ZJS |
174 | endswith_no_case(hostname, ".localhost") || |
175 | endswith_no_case(hostname, ".localhost.") || | |
63003524 DH |
176 | endswith_no_case(hostname, ".localhost.localdomain") || |
177 | endswith_no_case(hostname, ".localhost.localdomain."); | |
958b66ea LP |
178 | } |
179 | ||
46a5e0e7 LP |
180 | bool is_gateway_hostname(const char *hostname) { |
181 | assert(hostname); | |
182 | ||
183 | /* This tries to identify the valid syntaxes for the our | |
184 | * synthetic "gateway" host. */ | |
185 | ||
186 | return | |
5248e7e1 ZJS |
187 | strcaseeq(hostname, "_gateway") || strcaseeq(hostname, "_gateway.") |
188 | #if ENABLE_COMPAT_GATEWAY_HOSTNAME | |
189 | || strcaseeq(hostname, "gateway") || strcaseeq(hostname, "gateway.") | |
190 | #endif | |
191 | ; | |
46a5e0e7 LP |
192 | } |
193 | ||
958b66ea LP |
194 | int sethostname_idempotent(const char *s) { |
195 | char buf[HOST_NAME_MAX + 1] = {}; | |
196 | ||
197 | assert(s); | |
198 | ||
199 | if (gethostname(buf, sizeof(buf)) < 0) | |
200 | return -errno; | |
201 | ||
202 | if (streq(buf, s)) | |
203 | return 0; | |
204 | ||
205 | if (sethostname(s, strlen(s)) < 0) | |
206 | return -errno; | |
207 | ||
208 | return 1; | |
209 | } | |
139e5336 | 210 | |
2de2abad LB |
211 | int shorten_overlong(const char *s, char **ret) { |
212 | char *h, *p; | |
213 | ||
214 | /* Shorten an overlong name to HOST_NAME_MAX or to the first dot, | |
215 | * whatever comes earlier. */ | |
216 | ||
217 | assert(s); | |
218 | ||
219 | h = strdup(s); | |
220 | if (!h) | |
221 | return -ENOMEM; | |
222 | ||
223 | if (hostname_is_valid(h, false)) { | |
224 | *ret = h; | |
225 | return 0; | |
226 | } | |
227 | ||
228 | p = strchr(h, '.'); | |
229 | if (p) | |
230 | *p = 0; | |
231 | ||
232 | strshorten(h, HOST_NAME_MAX); | |
233 | ||
234 | if (!hostname_is_valid(h, false)) { | |
235 | free(h); | |
236 | return -EDOM; | |
237 | } | |
238 | ||
239 | *ret = h; | |
240 | return 1; | |
241 | } | |
242 | ||
f35cb39e LP |
243 | int read_etc_hostname_stream(FILE *f, char **ret) { |
244 | int r; | |
139e5336 | 245 | |
f35cb39e LP |
246 | assert(f); |
247 | assert(ret); | |
139e5336 | 248 | |
f35cb39e LP |
249 | for (;;) { |
250 | _cleanup_free_ char *line = NULL; | |
251 | char *p; | |
252 | ||
253 | r = read_line(f, LONG_LINE_MAX, &line); | |
254 | if (r < 0) | |
255 | return r; | |
256 | if (r == 0) /* EOF without any hostname? the file is empty, let's treat that exactly like no file at all: ENOENT */ | |
257 | return -ENOENT; | |
139e5336 | 258 | |
f35cb39e LP |
259 | p = strstrip(line); |
260 | ||
261 | /* File may have empty lines or comments, ignore them */ | |
262 | if (!IN_SET(*p, '\0', '#')) { | |
263 | char *copy; | |
264 | ||
265 | hostname_cleanup(p); /* normalize the hostname */ | |
266 | ||
267 | if (!hostname_is_valid(p, true)) /* check that the hostname we return is valid */ | |
268 | return -EBADMSG; | |
269 | ||
270 | copy = strdup(p); | |
271 | if (!copy) | |
139e5336 | 272 | return -ENOMEM; |
f35cb39e LP |
273 | |
274 | *ret = copy; | |
275 | return 0; | |
139e5336 MP |
276 | } |
277 | } | |
f35cb39e | 278 | } |
139e5336 | 279 | |
f35cb39e LP |
280 | int read_etc_hostname(const char *path, char **ret) { |
281 | _cleanup_fclose_ FILE *f = NULL; | |
282 | ||
283 | assert(ret); | |
284 | ||
285 | if (!path) | |
286 | path = "/etc/hostname"; | |
287 | ||
288 | f = fopen(path, "re"); | |
289 | if (!f) | |
290 | return -errno; | |
291 | ||
292 | return read_etc_hostname_stream(f, ret); | |
139e5336 | 293 | |
139e5336 | 294 | } |