src/patches/dnsmasq/0009-Use-inotify-instead-of-polling-on-Linux.patch

   1 From 193de4abf59e49c6b70d54cfe9720fcb95ca2f71 Mon Sep 17 00:00:00 2001
   2 From: Simon Kelley <simon@thekelleys.org.uk>
   3 Date: Wed, 10 Dec 2014 17:32:16 +0000
   4 Subject: [PATCH 09/55] Use inotify instead of polling on Linux.
   5
   6 This should solve problems people are seeing when a file changes
   7 twice within a second and thus is missed for polling.
   8 ---
   9  Makefile       |   2 +-
  10  bld/Android.mk |   2 +-
  11  src/dnsmasq.c  |  25 ++++++++++++--
  12  src/dnsmasq.h  |  11 ++++++-
  13  src/inotify.c  | 102 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  14  5 files changed, 137 insertions(+), 5 deletions(-)
  15  create mode 100644 src/inotify.c
  16
  17 diff --git a/Makefile b/Makefile
  18 index 58a7975f60b5..c340f1c7b59a 100644
  19 --- a/Makefile
  20 +++ b/Makefile
  21 @@ -69,7 +69,7 @@ objs = cache.o rfc1035.o util.o option.o forward.o network.o \
  22         dnsmasq.o dhcp.o lease.o rfc2131.o netlink.o dbus.o bpf.o \
  23         helper.o tftp.o log.o conntrack.o dhcp6.o rfc3315.o \
  24         dhcp-common.o outpacket.o radv.o slaac.o auth.o ipset.o \
  25 -       domain.o dnssec.o blockdata.o tables.o loop.o
  26 +       domain.o dnssec.o blockdata.o tables.o loop.o inotify.o
  27
  28  hdrs = dnsmasq.h config.h dhcp-protocol.h dhcp6-protocol.h \
  29         dns-protocol.h radv-protocol.h ip6addr.h
  30 diff --git a/bld/Android.mk b/bld/Android.mk
  31 index d855094eb264..d627796e8edc 100644
  32 --- a/bld/Android.mk
  33 +++ b/bld/Android.mk
  34 @@ -10,7 +10,7 @@ LOCAL_SRC_FILES :=  bpf.c cache.c dbus.c dhcp.c dnsmasq.c \
  35                     dhcp6.c rfc3315.c dhcp-common.c outpacket.c \
  36                     radv.c slaac.c auth.c ipset.c domain.c \
  37                     dnssec.c dnssec-openssl.c blockdata.c tables.c \
  38 -                   loop.c
  39 +                   loop.c inotify.c
  40
  41  LOCAL_MODULE := dnsmasq
  42
  43 diff --git a/src/dnsmasq.c b/src/dnsmasq.c
  44 index f4a89fc38183..bf2e25a55780 100644
  45 --- a/src/dnsmasq.c
  46 +++ b/src/dnsmasq.c
  47 @@ -315,9 +315,15 @@ int main (int argc, char **argv)
  48    if (daemon->port != 0)
  49      {
  50        cache_init();
  51 +
  52  #ifdef HAVE_DNSSEC
  53        blockdata_init();
  54  #endif
  55 +
  56 +#ifdef HAVE_LINUX_NETWORK
  57 +      if (!option_bool(OPT_NO_POLL))
  58 +       inotify_dnsmasq_init();
  59 +#endif
  60      }
  61
  62    if (option_bool(OPT_DBUS))
  63 @@ -793,6 +799,11 @@ int main (int argc, char **argv)
  64
  65    pid = getpid();
  66
  67 +#ifdef HAVE_LINUX_NETWORK
  68 +  /* Using inotify, have to select a resolv file at startup */
  69 +  poll_resolv(1, 0, now);
  70 +#endif
  71 +
  72    while (1)
  73      {
  74        int maxfd = -1;
  75 @@ -862,11 +873,16 @@ int main (int argc, char **argv)
  76  #if defined(HAVE_LINUX_NETWORK)
  77        FD_SET(daemon->netlinkfd, &rset);
  78        bump_maxfd(daemon->netlinkfd, &maxfd);
  79 +      if (daemon->port != 0 && !option_bool(OPT_NO_POLL))
  80 +       {
  81 +         FD_SET(daemon->inotifyfd, &rset);
  82 +         bump_maxfd(daemon->inotifyfd, &maxfd);
  83 +       }
  84  #elif defined(HAVE_BSD_NETWORK)
  85        FD_SET(daemon->routefd, &rset);
  86        bump_maxfd(daemon->routefd, &maxfd);
  87  #endif
  88 -
  89 +
  90        FD_SET(piperead, &rset);
  91        bump_maxfd(piperead, &maxfd);
  92
  93 @@ -929,6 +945,10 @@ int main (int argc, char **argv)
  94         route_sock();
  95  #endif
  96
  97 +#ifdef HAVE_LINUX_NETWORK
  98 +      if (daemon->port != 0 && !option_bool(OPT_NO_POLL) && FD_ISSET(daemon->inotifyfd, &rset) && inotify_check())
  99 +       poll_resolv(1, 1, now);
 100 +#else
 101        /* Check for changes to resolv files once per second max. */
 102        /* Don't go silent for long periods if the clock goes backwards. */
 103        if (daemon->last_resolv == 0 ||
 104 @@ -941,7 +961,8 @@ int main (int argc, char **argv)
 105           poll_resolv(0, daemon->last_resolv != 0, now);
 106           daemon->last_resolv = now;
 107         }
 108 -
 109 +#endif
 110 +
 111        if (FD_ISSET(piperead, &rset))
 112         async_event(piperead, now);
 113
 114 diff --git a/src/dnsmasq.h b/src/dnsmasq.h
 115 index e74b15a5459a..ebb6b957812f 100644
 116 --- a/src/dnsmasq.h
 117 +++ b/src/dnsmasq.h
 118 @@ -541,6 +541,10 @@ struct resolvc {
 119    int is_default, logged;
 120    time_t mtime;
 121    char *name;
 122 +#ifdef HAVE_LINUX_NETWORK
 123 +  int wd; /* inotify watch descriptor */
 124 +  char *file; /* pointer to file part if path */
 125 +#endif
 126  };
 127
 128  /* adn-hosts parms from command-line (also dhcp-hostsfile and dhcp-optsfile */
 129 @@ -998,7 +1002,7 @@ extern struct daemon {
 130    /* DHCP state */
 131    int dhcpfd, helperfd, pxefd;
 132  #if defined(HAVE_LINUX_NETWORK)
 133 -  int netlinkfd;
 134 +  int netlinkfd, inotifyfd;
 135  #elif defined(HAVE_BSD_NETWORK)
 136    int dhcp_raw_fd, dhcp_icmp_fd, routefd;
 137  #endif
 138 @@ -1469,3 +1473,8 @@ void loop_send_probes();
 139  int detect_loop(char *query, int type);
 140  #endif
 141
 142 +/* inotify.c */
 143 +#ifdef HAVE_LINUX_NETWORK
 144 +void inotify_dnsmasq_init();
 145 +int inotify_check(void);
 146 +#endif
 147 diff --git a/src/inotify.c b/src/inotify.c
 148 new file mode 100644
 149 index 000000000000..a0223443d6b6
 150 --- /dev/null
 151 +++ b/src/inotify.c
 152 @@ -0,0 +1,102 @@
 153 +/* dnsmasq is Copyright (c) 2000-2014 Simon Kelley
 154 +
 155 +   This program is free software; you can redistribute it and/or modify
 156 +   it under the terms of the GNU General Public License as published by
 157 +   the Free Software Foundation; version 2 dated June, 1991, or
 158 +   (at your option) version 3 dated 29 June, 2007.
 159 +
 160 +   This program is distributed in the hope that it will be useful,
 161 +   but WITHOUT ANY WARRANTY; without even the implied warranty of
 162 +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 163 +   GNU General Public License for more details.
 164 +
 165 +   You should have received a copy of the GNU General Public License
 166 +   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 167 +*/
 168 +
 169 +#include "dnsmasq.h"
 170 +#include <sys/inotify.h>
 171 +
 172 +#ifdef HAVE_LINUX_NETWORK
 173 +
 174 +/* the strategy is to set a inotify on the directories containing
 175 +   resolv files, for any files in the directory which are close-write
 176 +   or moved into the directory.
 177 +
 178 +   When either of those happen, we look to see if the file involved
 179 +   is actually a resolv-file, and if so, call poll-resolv with
 180 +   the "force" argument, to ensure it's read.
 181 +
 182 +   This adds one new error condition: the directories containing
 183 +   all specified resolv-files must exist at start-up, even if the actual
 184 +   files don't.
 185 +*/
 186 +
 187 +static char *inotify_buffer;
 188 +#define INOTIFY_SZ (sizeof(struct inotify_event) + NAME_MAX + 1)
 189 +
 190 +void inotify_dnsmasq_init()
 191 +{
 192 +  struct resolvc *res;
 193 +
 194 +  inotify_buffer = safe_malloc(INOTIFY_SZ);
 195 +
 196 +  daemon->inotifyfd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
 197 +
 198 +  if (daemon->inotifyfd == -1)
 199 +    die(_("failed to create inotify: %s"), NULL, EC_MISC);
 200 +
 201 +  for (res = daemon->resolv_files; res; res = res->next)
 202 +    {
 203 +      char *d = strrchr(res->name, '/');
 204 +
 205 +      if (!d)
 206 +       die(_("resolv-file %s not an absolute path"), res->name, EC_MISC);
 207 +
 208 +      *d = 0; /* make ->name just directory */
 209 +      res->wd = inotify_add_watch(daemon->inotifyfd, res->name, IN_CLOSE_WRITE | IN_MOVED_TO);
 210 +      res->file = d+1; /* pointer to filename */
 211 +
 212 +      if (res->wd == -1 && errno == ENOENT)
 213 +       die(_("directory %s for resolv-file is missing, cannot poll"), res->name, EC_MISC);
 214 +
 215 +      *d = '/'; /* restore name */
 216 +
 217 +      if (res->wd == -1)
 218 +       die(_("failed to create inotify for %s: %s"), res->name, EC_MISC);
 219 +    }
 220 +}
 221 +
 222 +int inotify_check(void)
 223 +{
 224 +  int hit = 0;
 225 +
 226 +  while (1)
 227 +    {
 228 +      int rc;
 229 +      char *p;
 230 +      struct resolvc *res;
 231 +      struct inotify_event *in;
 232 +
 233 +      while ((rc = read(daemon->inotifyfd, inotify_buffer, INOTIFY_SZ)) == -1 && errno == EINTR);
 234 +
 235 +      if (rc <= 0)
 236 +       break;
 237 +
 238 +      for (p = inotify_buffer; rc - (p - inotify_buffer) >= (int)sizeof(struct inotify_event); p += sizeof(struct inotify_event) + in->len)
 239 +       {
 240 +         in = (struct inotify_event*)p;
 241 +
 242 +         for (res = daemon->resolv_files; res; res = res->next)
 243 +           if (res->wd == in->wd && in->len != 0 && strcmp(res->file, in->name) == 0)
 244 +             hit = 1;
 245 +       }
 246 +    }
 247 +
 248 +  return hit;
 249 +}
 250 +
 251 +#endif
 252 +
 253 +
 254 +
 255 --
 256 2.1.0
 257