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/* dnsmasq is Copyright (c) 2000-2014 Simon Kelley
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 dated June, 1991, or
(at your option) version 3 dated 29 June, 2007.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "dnsmasq.h"
#ifdef HAVE_LINUX_NETWORK
#include <sys/inotify.h>
#ifdef HAVE_DHCP
static void check_for_dhcp_inotify(struct inotify_event *in, time_t now);
#endif
/* the strategy is to set a inotify on the directories containing
resolv files, for any files in the directory which are close-write
or moved into the directory.
When either of those happen, we look to see if the file involved
is actually a resolv-file, and if so, call poll-resolv with
the "force" argument, to ensure it's read.
This adds one new error condition: the directories containing
all specified resolv-files must exist at start-up, even if the actual
files don't.
*/
static char *inotify_buffer;
#define INOTIFY_SZ (sizeof(struct inotify_event) + NAME_MAX + 1)
void inotify_dnsmasq_init()
{
struct resolvc *res;
inotify_buffer = safe_malloc(INOTIFY_SZ);
daemon->inotifyfd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
if (daemon->inotifyfd == -1)
die(_("failed to create inotify: %s"), NULL, EC_MISC);
for (res = daemon->resolv_files; res; res = res->next)
{
char *d = NULL, *path;
if (!(path = realpath(res->name, NULL)))
{
/* realpath will fail if the file doesn't exist, but
dnsmasq copes with missing files, so fall back
and assume that symlinks are not in use in that case. */
if (errno == ENOENT)
path = res->name;
else
die(_("cannot cannonicalise resolv-file %s: %s"), res->name, EC_MISC);
}
if ((d = strrchr(path, '/')))
{
*d = 0; /* make path just directory */
res->wd = inotify_add_watch(daemon->inotifyfd, path, IN_CLOSE_WRITE | IN_MOVED_TO);
res->file = d+1; /* pointer to filename */
*d = '/';
if (res->wd == -1 && errno == ENOENT)
die(_("directory %s for resolv-file is missing, cannot poll"), res->name, EC_MISC);
if (res->wd == -1)
die(_("failed to create inotify for %s: %s"), res->name, EC_MISC);
}
}
}
int inotify_check(time_t now)
{
int hit = 0;
while (1)
{
int rc;
char *p;
struct resolvc *res;
struct inotify_event *in;
while ((rc = read(daemon->inotifyfd, inotify_buffer, INOTIFY_SZ)) == -1 && errno == EINTR);
if (rc <= 0)
break;
for (p = inotify_buffer; rc - (p - inotify_buffer) >= (int)sizeof(struct inotify_event); p += sizeof(struct inotify_event) + in->len)
{
in = (struct inotify_event*)p;
for (res = daemon->resolv_files; res; res = res->next)
if (res->wd == in->wd && in->len != 0 && strcmp(res->file, in->name) == 0)
hit = 1;
#ifdef HAVE_DHCP
if (daemon->dhcp || daemon->doing_dhcp6)
check_for_dhcp_inotify(in, now);
#endif
}
}
return hit;
}
#ifdef HAVE_DHCP
/* initialisation for dhcp-hostdir. Set inotify watch for each directory, and read pre-existing files */
void set_dhcp_inotify(void)
{
struct hostsfile *ah;
for (ah = daemon->inotify_hosts; ah; ah = ah->next)
{
DIR *dir_stream = NULL;
struct dirent *ent;
struct stat buf;
if (stat(ah->fname, &buf) == -1 || !(S_ISDIR(buf.st_mode)))
{
my_syslog(LOG_ERR, _("bad directory in dhcp-hostsdir %s"), ah->fname);
continue;
}
if (!(ah->flags & AH_WD_DONE))
{
ah->wd = inotify_add_watch(daemon->inotifyfd, ah->fname, IN_CLOSE_WRITE | IN_MOVED_TO);
ah->flags |= AH_WD_DONE;
}
/* Read contents of dir _after_ calling add_watch, in the ho[e of avoiding
a race which misses files being added as we start */
if (ah->wd == -1 || !(dir_stream = opendir(ah->fname)))
{
my_syslog(LOG_ERR, _("failed to create inotify for %s"), ah->fname);
continue;
}
while ((ent = readdir(dir_stream)))
{
size_t lendir = strlen(ah->fname);
size_t lenfile = strlen(ent->d_name);
char *path;
/* ignore emacs backups and dotfiles */
if (lenfile == 0 ||
ent->d_name[lenfile - 1] == '~' ||
(ent->d_name[0] == '#' && ent->d_name[lenfile - 1] == '#') ||
ent->d_name[0] == '.')
continue;
if ((path = whine_malloc(lendir + lenfile + 2)))
{
strcpy(path, ah->fname);
strcat(path, "/");
strcat(path, ent->d_name);
/* ignore non-regular files */
if (stat(path, &buf) != -1 && S_ISREG(buf.st_mode))
option_read_hostsfile(path);
free(path);
}
}
}
}
static void check_for_dhcp_inotify(struct inotify_event *in, time_t now)
{
struct hostsfile *ah;
/* ignore emacs backups and dotfiles */
if (in->len == 0 ||
in->name[in->len - 1] == '~' ||
(in->name[0] == '#' && in->name[in->len - 1] == '#') ||
in->name[0] == '.')
return;
for (ah = daemon->inotify_hosts; ah; ah = ah->next)
if (ah->wd == in->wd)
{
size_t lendir = strlen(ah->fname);
char *path;
if ((path = whine_malloc(lendir + in->len + 2)))
{
strcpy(path, ah->fname);
strcat(path, "/");
strcat(path, in->name);
if (option_read_hostsfile(path))
{
/* Propogate the consequences of loading a new dhcp-host */
dhcp_update_configs(daemon->dhcp_conf);
lease_update_from_configs();
lease_update_file(now);
lease_update_dns(1);
}
free(path);
}
return;
}
}
#endif /* DHCP */
#endif /* LINUX_NETWORK */
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