Use inotify instead of polling on Linux.
This should solve problems people are seeing when a file changes
twice within a second and thus is missed for polling.
diff --git a/Makefile b/Makefile
index 58a7975..c340f1c 100644
--- a/Makefile
+++ b/Makefile
@@ -69,7 +69,7 @@
dnsmasq.o dhcp.o lease.o rfc2131.o netlink.o dbus.o bpf.o \
helper.o tftp.o log.o conntrack.o dhcp6.o rfc3315.o \
dhcp-common.o outpacket.o radv.o slaac.o auth.o ipset.o \
- domain.o dnssec.o blockdata.o tables.o loop.o
+ domain.o dnssec.o blockdata.o tables.o loop.o inotify.o
hdrs = dnsmasq.h config.h dhcp-protocol.h dhcp6-protocol.h \
dns-protocol.h radv-protocol.h ip6addr.h
diff --git a/bld/Android.mk b/bld/Android.mk
index d855094..d627796 100644
--- a/bld/Android.mk
+++ b/bld/Android.mk
@@ -10,7 +10,7 @@
dhcp6.c rfc3315.c dhcp-common.c outpacket.c \
radv.c slaac.c auth.c ipset.c domain.c \
dnssec.c dnssec-openssl.c blockdata.c tables.c \
- loop.c
+ loop.c inotify.c
LOCAL_MODULE := dnsmasq
diff --git a/src/dnsmasq.c b/src/dnsmasq.c
index f4a89fc..bf2e25a 100644
--- a/src/dnsmasq.c
+++ b/src/dnsmasq.c
@@ -315,9 +315,15 @@
if (daemon->port != 0)
{
cache_init();
+
#ifdef HAVE_DNSSEC
blockdata_init();
#endif
+
+#ifdef HAVE_LINUX_NETWORK
+ if (!option_bool(OPT_NO_POLL))
+ inotify_dnsmasq_init();
+#endif
}
if (option_bool(OPT_DBUS))
@@ -793,6 +799,11 @@
pid = getpid();
+#ifdef HAVE_LINUX_NETWORK
+ /* Using inotify, have to select a resolv file at startup */
+ poll_resolv(1, 0, now);
+#endif
+
while (1)
{
int maxfd = -1;
@@ -862,11 +873,16 @@
#if defined(HAVE_LINUX_NETWORK)
FD_SET(daemon->netlinkfd, &rset);
bump_maxfd(daemon->netlinkfd, &maxfd);
+ if (daemon->port != 0 && !option_bool(OPT_NO_POLL))
+ {
+ FD_SET(daemon->inotifyfd, &rset);
+ bump_maxfd(daemon->inotifyfd, &maxfd);
+ }
#elif defined(HAVE_BSD_NETWORK)
FD_SET(daemon->routefd, &rset);
bump_maxfd(daemon->routefd, &maxfd);
#endif
-
+
FD_SET(piperead, &rset);
bump_maxfd(piperead, &maxfd);
@@ -929,6 +945,10 @@
route_sock();
#endif
+#ifdef HAVE_LINUX_NETWORK
+ if (daemon->port != 0 && !option_bool(OPT_NO_POLL) && FD_ISSET(daemon->inotifyfd, &rset) && inotify_check())
+ poll_resolv(1, 1, now);
+#else
/* Check for changes to resolv files once per second max. */
/* Don't go silent for long periods if the clock goes backwards. */
if (daemon->last_resolv == 0 ||
@@ -941,7 +961,8 @@
poll_resolv(0, daemon->last_resolv != 0, now);
daemon->last_resolv = now;
}
-
+#endif
+
if (FD_ISSET(piperead, &rset))
async_event(piperead, now);
diff --git a/src/dnsmasq.h b/src/dnsmasq.h
index e74b15a..ebb6b95 100644
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -541,6 +541,10 @@
int is_default, logged;
time_t mtime;
char *name;
+#ifdef HAVE_LINUX_NETWORK
+ int wd; /* inotify watch descriptor */
+ char *file; /* pointer to file part if path */
+#endif
};
/* adn-hosts parms from command-line (also dhcp-hostsfile and dhcp-optsfile */
@@ -998,7 +1002,7 @@
/* DHCP state */
int dhcpfd, helperfd, pxefd;
#if defined(HAVE_LINUX_NETWORK)
- int netlinkfd;
+ int netlinkfd, inotifyfd;
#elif defined(HAVE_BSD_NETWORK)
int dhcp_raw_fd, dhcp_icmp_fd, routefd;
#endif
@@ -1469,3 +1473,8 @@
int detect_loop(char *query, int type);
#endif
+/* inotify.c */
+#ifdef HAVE_LINUX_NETWORK
+void inotify_dnsmasq_init();
+int inotify_check(void);
+#endif
diff --git a/src/inotify.c b/src/inotify.c
new file mode 100644
index 0000000..a022344
--- /dev/null
+++ b/src/inotify.c
@@ -0,0 +1,102 @@
+/* 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"
+#include <sys/inotify.h>
+
+#ifdef HAVE_LINUX_NETWORK
+
+/* 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 = strrchr(res->name, '/');
+
+ if (!d)
+ die(_("resolv-file %s not an absolute path"), res->name, EC_MISC);
+
+ *d = 0; /* make ->name just directory */
+ res->wd = inotify_add_watch(daemon->inotifyfd, res->name, IN_CLOSE_WRITE | IN_MOVED_TO);
+ res->file = d+1; /* pointer to filename */
+
+ if (res->wd == -1 && errno == ENOENT)
+ die(_("directory %s for resolv-file is missing, cannot poll"), res->name, EC_MISC);
+
+ *d = '/'; /* restore name */
+
+ if (res->wd == -1)
+ die(_("failed to create inotify for %s: %s"), res->name, EC_MISC);
+ }
+}
+
+int inotify_check(void)
+{
+ 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;
+ }
+ }
+
+ return hit;
+}
+
+#endif
+
+
+
