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