Index: net/base/host_resolver.cc |
diff --git a/net/base/host_resolver.cc b/net/base/host_resolver.cc |
index 23a1c00940e75c1c9a5fcf36ad386789eb48b3ad..ec693eedf74a807ee7a9c79164130620d685e6d9 100644 |
--- a/net/base/host_resolver.cc |
+++ b/net/base/host_resolver.cc |
@@ -21,6 +21,12 @@ |
#include "net/base/address_list.h" |
#include "net/base/net_errors.h" |
+#if defined(OS_LINUX) |
+#include "base/singleton.h" |
+#include "base/thread_local_storage.h" |
+#include "base/time.h" |
+#endif |
+ |
#if defined(OS_WIN) |
#include "net/base/winsock_init.h" |
#endif |
@@ -40,6 +46,70 @@ HostMapper* SetHostMapper(HostMapper* value) { |
return value; |
} |
+#if defined(OS_LINUX) |
+// On Linux changes to /etc/resolv.conf can go unnoticed thus resulting in |
+// DNS queries failing either because nameservers are unknown on startup |
+// or because nameserver info has changed as a result of e.g. connecting to |
+// a new network. Some distributions patch glibc to stat /etc/resolv.conf |
+// to try to automatically detect such changes but these patches are not |
+// universal and even patched systems such as Jaunty appear to need calls |
+// to res_ninit to reload the nameserver information in different threads. |
+// |
+// We adopt the Mozilla solution here which is to call res_ninit when |
+// lookups fail and to rate limit the reloading to once per second per |
+// thread. |
+ |
+// Keep a timer per calling thread to rate limit the calling of res_ninit. |
+class DnsReloadTimer { |
+ public: |
+ DnsReloadTimer() { |
+ tls_index_.Initialize(SlotReturnFunction); |
+ } |
+ |
+ ~DnsReloadTimer() { } |
+ |
+ // Check if the timer for the calling thread has expired. When no |
+ // timer exists for the calling thread, create one. |
+ bool Expired() { |
+ const base::TimeDelta kRetryTime = base::TimeDelta::FromSeconds(1); |
+ base::TimeTicks now = base::TimeTicks::Now(); |
+ base::TimeTicks* timer_ptr = |
+ static_cast<base::TimeTicks*>(tls_index_.Get()); |
+ |
+ if (!timer_ptr) { |
+ timer_ptr = new base::TimeTicks(); |
+ *timer_ptr = base::TimeTicks::Now(); |
+ tls_index_.Set(timer_ptr); |
+ // Return true to reload dns info on the first call for each thread. |
+ return true; |
+ } else if (now - *timer_ptr > kRetryTime) { |
+ *timer_ptr = now; |
+ return true; |
+ } else { |
+ return false; |
+ } |
+ } |
+ |
+ // Free the allocated timer. |
+ static void SlotReturnFunction(void* data) { |
+ base::TimeTicks* tls_data = static_cast<base::TimeTicks*>(data); |
+ delete tls_data; |
+ } |
+ |
+ private: |
+ // We use thread local storage to identify which base::TimeTicks to |
+ // interact with. |
+ static ThreadLocalStorage::Slot tls_index_ ; |
+ |
+ DISALLOW_COPY_AND_ASSIGN(DnsReloadTimer); |
+}; |
+ |
+// A TLS slot to the TimeTicks for the current thread. |
+// static |
+ThreadLocalStorage::Slot DnsReloadTimer::tls_index_(base::LINKER_INITIALIZED); |
+ |
+#endif // defined(OS_LINUX) |
+ |
static int HostResolverProc( |
const std::string& host, const std::string& port, struct addrinfo** out) { |
struct addrinfo hints = {0}; |
@@ -76,10 +146,14 @@ static int HostResolverProc( |
int err = getaddrinfo(host.c_str(), port.c_str(), &hints, out); |
#if defined(OS_LINUX) |
+ net::DnsReloadTimer* dns_timer = Singleton<net::DnsReloadTimer>::get(); |
// 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 && !res_init()) |
- err = getaddrinfo(host.c_str(), port.c_str(), &hints, out); |
+ if (err && dns_timer->Expired()) { |
+ res_nclose(&_res); |
+ if (!res_ninit(&_res)) |
+ err = getaddrinfo(host.c_str(), port.c_str(), &hints, out); |
+ } |
#endif |
return err ? ERR_NAME_NOT_RESOLVED : OK; |