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114 lines
3.2 KiB
C
114 lines
3.2 KiB
C
/* dnsmasq is Copyright (c) 2000-2014 Simon Kelley
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 dated June, 1991, or
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(at your option) version 3 dated 29 June, 2007.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "dnsmasq.h"
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#ifdef HAVE_LINUX_NETWORK
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#include <sys/inotify.h>
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/* the strategy is to set a inotify on the directories containing
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resolv files, for any files in the directory which are close-write
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or moved into the directory.
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When either of those happen, we look to see if the file involved
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is actually a resolv-file, and if so, call poll-resolv with
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the "force" argument, to ensure it's read.
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This adds one new error condition: the directories containing
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all specified resolv-files must exist at start-up, even if the actual
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files don't.
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*/
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static char *inotify_buffer;
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#define INOTIFY_SZ (sizeof(struct inotify_event) + NAME_MAX + 1)
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void inotify_dnsmasq_init()
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{
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struct resolvc *res;
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inotify_buffer = safe_malloc(INOTIFY_SZ);
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daemon->inotifyfd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
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if (daemon->inotifyfd == -1)
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die(_("failed to create inotify: %s"), NULL, EC_MISC);
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for (res = daemon->resolv_files; res; res = res->next)
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{
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char *d = NULL, *path;
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if (!(path = realpath(res->name, NULL)))
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{
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/* realpath will fail if the file doesn't exist, but
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dnsmasq copes with missing files, so fall back
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and assume that symlinks are not in use in that case. */
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if (errno == ENOENT)
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path = res->name;
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else
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die(_("cannot cannonicalise resolv-file %s: %s"), res->name, EC_MISC);
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}
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if ((d = strrchr(path, '/')))
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{
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*d = 0; /* make path just directory */
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res->wd = inotify_add_watch(daemon->inotifyfd, path, IN_CLOSE_WRITE | IN_MOVED_TO);
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res->file = d+1; /* pointer to filename */
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*d = '/';
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if (res->wd == -1 && errno == ENOENT)
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die(_("directory %s for resolv-file is missing, cannot poll"), res->name, EC_MISC);
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if (res->wd == -1)
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die(_("failed to create inotify for %s: %s"), res->name, EC_MISC);
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}
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}
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}
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int inotify_check(void)
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{
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int hit = 0;
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while (1)
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{
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int rc;
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char *p;
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struct resolvc *res;
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struct inotify_event *in;
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while ((rc = read(daemon->inotifyfd, inotify_buffer, INOTIFY_SZ)) == -1 && errno == EINTR);
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if (rc <= 0)
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break;
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for (p = inotify_buffer; rc - (p - inotify_buffer) >= (int)sizeof(struct inotify_event); p += sizeof(struct inotify_event) + in->len)
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{
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in = (struct inotify_event*)p;
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for (res = daemon->resolv_files; res; res = res->next)
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if (res->wd == in->wd && in->len != 0 && strcmp(res->file, in->name) == 0)
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hit = 1;
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}
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}
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return hit;
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}
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#endif
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