1 /* dnsmasq is Copyright (c) 2000-2022 Simon Kelley
3 This program is free software; you can redistribute it and/or modify
4 it under the terms of the GNU General Public License as published by
5 the Free Software Foundation; version 2 dated June, 1991, or
6 (at your option) version 3 dated 29 June, 2007.
8 This program is distributed in the hope that it will be useful,
9 but WITHOUT ANY WARRANTY; without even the implied warranty of
10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 GNU General Public License for more details.
13 You should have received a copy of the GNU General Public License
14 along with this program. If not, see <http://www.gnu.org/licenses/>.
20 #include <sys/inotify.h>
21 #include <sys/param.h> /* For MAXSYMLINKS */
23 /* the strategy is to set an inotify on the directories containing
24 resolv files, for any files in the directory which are close-write
25 or moved into the directory.
27 When either of those happen, we look to see if the file involved
28 is actually a resolv-file, and if so, call poll-resolv with
29 the "force" argument, to ensure it's read.
31 This adds one new error condition: the directories containing
32 all specified resolv-files must exist at start-up, even if the actual
36 static char *inotify_buffer;
37 #define INOTIFY_SZ (sizeof(struct inotify_event) + NAME_MAX + 1)
39 /* If path is a symbolic link, return the path it
40 points to, made absolute if relative.
41 If path doesn't exist or is not a symlink, return NULL.
42 Return value is malloc'ed */
43 static char *my_readlink(char *path)
45 ssize_t rc, size = 64;
50 buf = safe_malloc(size);
51 rc = readlink(path, buf, (size_t)size);
55 /* Not link or doesn't exist. */
56 if (errno == EINVAL || errno == ENOENT)
62 die(_("cannot access path %s: %s"), path, EC_MISC);
69 if (buf[0] != '/' && ((d = strrchr(path, '/'))))
71 /* Add path to relative link */
72 char *new_buf = safe_malloc((d - path) + strlen(buf) + 2);
74 strcpy(new_buf, path);
82 /* Buffer too small, increase and retry */
88 void inotify_dnsmasq_init()
91 inotify_buffer = safe_malloc(INOTIFY_SZ);
92 daemon->inotifyfd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
94 if (daemon->inotifyfd == -1)
95 die(_("failed to create inotify: %s"), NULL, EC_MISC);
97 if (option_bool(OPT_NO_RESOLV))
100 for (res = daemon->resolv_files; res; res = res->next)
102 char *d, *new_path, *path = safe_malloc(strlen(res->name) + 1);
103 int links = MAXSYMLINKS;
105 strcpy(path, res->name);
107 /* Follow symlinks until we reach a non-symlink, or a non-existent file. */
108 while ((new_path = my_readlink(path)))
111 die(_("too many symlinks following %s"), res->name, EC_MISC);
118 if ((d = strrchr(path, '/')))
120 *d = 0; /* make path just directory */
121 res->wd = inotify_add_watch(daemon->inotifyfd, path, IN_CLOSE_WRITE | IN_MOVED_TO);
123 res->file = d+1; /* pointer to filename */
126 if (res->wd == -1 && errno == ENOENT)
127 die(_("directory %s for resolv-file is missing, cannot poll"), res->name, EC_MISC);
131 die(_("failed to create inotify for %s: %s"), res->name, EC_MISC);
136 static struct hostsfile *dyndir_addhosts(struct dyndir *dd, char *path)
138 /* Check if this file is already known in dd->files */
139 struct hostsfile *ah = NULL;
140 for(ah = dd->files; ah; ah = ah->next)
141 if(ah && ah->fname && strcmp(path, ah->fname) == 0)
144 /* Not known, create new hostsfile record for this dyndir */
145 struct hostsfile *newah = NULL;
146 if(!(newah = whine_malloc(sizeof(struct hostsfile))))
149 /* Add this file to the tip of the linked list */
150 newah->next = dd->files;
153 /* Copy flags, set index and the full file path */
154 newah->flags = dd->flags;
155 newah->index = daemon->host_index++;
162 /* initialisation for dynamic-dir. Set inotify watch for each directory, and read pre-existing files */
163 void set_dynamic_inotify(int flag, int total_size, struct crec **rhash, int revhashsz)
167 for (dd = daemon->dynamic_dirs; dd; dd = dd->next)
169 DIR *dir_stream = NULL;
173 if (!(dd->flags & flag))
176 if (stat(dd->dname, &buf) == -1)
178 my_syslog(LOG_ERR, _("bad dynamic directory %s: %s"),
179 dd->dname, strerror(errno));
183 if (!(S_ISDIR(buf.st_mode)))
185 my_syslog(LOG_ERR, _("bad dynamic directory %s: %s"),
186 dd->dname, _("not a directory"));
190 if (!(dd->flags & AH_WD_DONE))
192 dd->wd = inotify_add_watch(daemon->inotifyfd, dd->dname, IN_CLOSE_WRITE | IN_MOVED_TO | IN_DELETE);
193 dd->flags |= AH_WD_DONE;
196 /* Read contents of dir _after_ calling add_watch, in the hope of avoiding
197 a race which misses files being added as we start */
198 if (dd->wd == -1 || !(dir_stream = opendir(dd->dname)))
200 my_syslog(LOG_ERR, _("failed to create inotify for %s: %s"),
201 dd->dname, strerror(errno));
205 while ((ent = readdir(dir_stream)))
207 size_t lendir = strlen(dd->dname);
208 size_t lenfile = strlen(ent->d_name);
211 /* ignore emacs backups and dotfiles */
213 ent->d_name[lenfile - 1] == '~' ||
214 (ent->d_name[0] == '#' && ent->d_name[lenfile - 1] == '#') ||
215 ent->d_name[0] == '.')
218 if ((path = whine_malloc(lendir + lenfile + 2)))
220 struct hostsfile *ah;
222 strcpy(path, dd->dname);
224 strcat(path, ent->d_name);
226 if (!(ah = dyndir_addhosts(dd, path)))
232 /* ignore non-regular files */
233 if (stat(path, &buf) != -1 && S_ISREG(buf.st_mode))
235 if (dd->flags & AH_HOSTS)
236 total_size = read_hostsfile(path, ah->index, total_size, rhash, revhashsz);
238 else if (dd->flags & (AH_DHCP_HST | AH_DHCP_OPT))
239 option_read_dynfile(path, dd->flags);
245 closedir(dir_stream);
249 int inotify_check(time_t now)
259 struct inotify_event *in;
261 while ((rc = read(daemon->inotifyfd, inotify_buffer, INOTIFY_SZ)) == -1 && errno == EINTR);
266 for (p = inotify_buffer; rc - (p - inotify_buffer) >= (int)sizeof(struct inotify_event); p += sizeof(struct inotify_event) + in->len)
270 in = (struct inotify_event*)p;
272 /* ignore emacs backups and dotfiles */
273 if (in->len == 0 || (namelen = strlen(in->name)) == 0 ||
274 in->name[namelen - 1] == '~' ||
275 (in->name[0] == '#' && in->name[namelen - 1] == '#') ||
279 for (res = daemon->resolv_files; res; res = res->next)
280 if (res->wd == in->wd && strcmp(res->file, in->name) == 0)
283 for (dd = daemon->dynamic_dirs; dd; dd = dd->next)
284 if (dd->wd == in->wd)
286 size_t lendir = strlen(dd->dname);
289 if ((path = whine_malloc(lendir + in->len + 2)))
291 struct hostsfile *ah = NULL;
293 strcpy(path, dd->dname);
295 strcat(path, in->name);
297 /* Is this is a deletion event? */
298 if (in->mask & IN_DELETE)
299 my_syslog(LOG_INFO, _("inotify: %s removed"), path);
301 my_syslog(LOG_INFO, _("inotify: %s new or modified"), path);
303 if (dd->flags & AH_HOSTS)
305 if ((ah = dyndir_addhosts(dd, path)))
307 const unsigned int removed = cache_remove_uid(ah->index);
309 my_syslog(LOG_INFO, _("inotify: flushed %u names read from %s"), removed, path);
311 /* (Re-)load hostsfile only if this event isn't triggered by deletion */
312 if (!(in->mask & IN_DELETE))
313 read_hostsfile(path, ah->index, 0, NULL, 0);
315 if (daemon->dhcp || daemon->doing_dhcp6)
317 /* Propagate the consequences of loading a new dhcp-host */
318 dhcp_update_configs(daemon->dhcp_conf);
319 lease_update_from_configs();
320 lease_update_file(now);
327 else if (dd->flags & AH_DHCP_HST)
329 if (option_read_dynfile(path, AH_DHCP_HST))
331 /* Propagate the consequences of loading a new dhcp-host */
332 dhcp_update_configs(daemon->dhcp_conf);
333 lease_update_from_configs();
334 lease_update_file(now);
338 else if (dd->flags & AH_DHCP_OPT)
339 option_read_dynfile(path, AH_DHCP_OPT);