Linux: Monitor resolv.conf for changes and use that to reload resolver.

net/base/host_resolver_proc.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/base/host_resolver_proc.h"
 
 #include "build/build_config.h"
 
 #include "base/logging.h"
 #include "net/base/address_list.h"
-#include "net/base/dns_reload_timer.h"
+#include "net/base/dns_reloader.h"
 #include "net/base/net_errors.h"
 #include "net/base/sys_addrinfo.h"
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
 #include <resolv.h>
 #endif
 
 namespace net {
 
 namespace {
@@ skipping 167 matching lines @@
   // loopback addresses.
   if (host_resolver_flags & HOST_RESOLVER_LOOPBACK_ONLY)
     hints.ai_flags &= ~AI_ADDRCONFIG;
 
   if (host_resolver_flags & HOST_RESOLVER_CANONNAME)
     hints.ai_flags |= AI_CANONNAME;
 
   // Restrict result set to only this socket type to avoid duplicates.
   hints.ai_socktype = SOCK_STREAM;
 
+#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD) && \

[eroman, 2011/07/25 20:13:03]

nit: I wander if it would be cleaner to internalize the platform checks into
DnsReloaderMaybeReload() itself -- i.e. define it on all platforms, but have it
be a no-op on platforms where it isn't necessary (or isn't supported).

[Craig, 2011/08/03 19:30:58]

I'll do this but I'm going to chase the symlink stuff around first and report
back on that.

+    !defined(OS_ANDROID)
+  DnsReloaderMaybeReload();
+#endif
   int err = getaddrinfo(host.c_str(), NULL, &hints, &ai);
   bool should_retry = false;
-#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD) && \
-    !defined(OS_ANDROID)
-  // If we fail, re-initialise the resolver just in case there have been any
-  // changes to /etc/resolv.conf and retry. See http://crbug.com/11380 for info.
-  if (err && DnsReloadTimerHasExpired()) {
-    // When there's no network connection, _res may not be initialized by
-    // getaddrinfo. Therefore, we call res_nclose only when there are ns
-    // entries.
-    if (_res.nscount > 0)
-      res_nclose(&_res);
-    if (!res_ninit(&_res))
-      should_retry = true;
-  }
-#endif
   // If the lookup was restricted (either by address family, or address
   // detection), and the results where all localhost of a single family,
   // maybe we should retry.  There were several bugs related to these
   // issues, for example http://crbug.com/42058 and http://crbug.com/49024
   if ((hints.ai_family != AF_UNSPEC || hints.ai_flags & AI_ADDRCONFIG) &&
       err == 0 && IsAllLocalhostOfOneFamily(ai)) {
     if (host_resolver_flags & HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6) {
       hints.ai_family = AF_UNSPEC;
       should_retry = true;
     }
@@ skipping 30 matching lines @@
 #endif
 
     return ERR_NAME_NOT_RESOLVED;
   }
 
   *addrlist = AddressList::CreateByAdoptingFromSystem(ai);
   return OK;
 }
 
 }  // namespace net