Cronet: Use stale DNS cache entries experimentally.

components/cronet/stale_host_resolver_unittest.cc

Index: components/cronet/stale_host_resolver_unittest.cc
diff --git a/components/cronet/stale_host_resolver_unittest.cc b/components/cronet/stale_host_resolver_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..cf3d6976952976ab9cff4f4caeafefcb07f5195e
--- /dev/null
+++ b/components/cronet/stale_host_resolver_unittest.cc
@@ -0,0 +1,496 @@
+// Copyright 2016 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 "components/cronet/stale_host_resolver.h"
+
+#include "base/callback_helpers.h"
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "base/memory/ref_counted.h"
+#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
+#include "base/test/test_timeouts.h"
+#include "base/values.h"
+#include "components/cronet/url_request_context_config.h"
+#include "net/base/net_errors.h"
+#include "net/cert/cert_verifier.h"
+#include "net/dns/host_resolver_proc.h"
+#include "net/http/http_network_session.h"
+#include "net/proxy/proxy_config.h"
+#include "net/proxy/proxy_config_service_fixed.h"
+#include "net/url_request/url_request_context.h"
+#include "net/url_request/url_request_context_builder.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cronet {
+
+namespace {
+
+const char kHostname[] = "example.com";
+const char kCacheAddress[] = "1.1.1.1";
+const char kNetworkAddress[] = "2.2.2.2";
+const char kUninitializedAddress[] = "3.3.3.3";
+const int kCacheEntryTTLSec = 300;
+
+const int kNoStaleDelaySec = 0;
+const int kLongStaleDelaySec = 3600;
+const uint16_t kPort = 12345;
+
+const int kAgeFreshSec = 0;
+const int kAgeExpiredSec = kCacheEntryTTLSec * 2;
+
+// How long to wait for resolve calls to return. If the tests are working
+// correctly, we won't end up waiting this long -- it's just a backup.
+const int kWaitTimeoutSec = 1;
+
+net::AddressList MakeAddressList(const char* ip_address_str) {
+  net::IPAddress address;
+  bool rv = address.AssignFromIPLiteral(ip_address_str);
+  DCHECK(rv);
+
+  net::AddressList address_list;
+  address_list.push_back(net::IPEndPoint(address, 0u));
+  return address_list;
+}
+
+class MockHostResolverProc : public net::HostResolverProc {
+ public:
+  MockHostResolverProc() : HostResolverProc(nullptr) {}
+
+  ~MockHostResolverProc() override {}
+
+  int Resolve(const std::string& hostname,
+              net::AddressFamily address_family,
+              net::HostResolverFlags host_resolver_flags,
+              net::AddressList* address_list,
+              int* os_error) override {
+    *address_list = MakeAddressList(kNetworkAddress);
+    return net::OK;
+  }
+};
+
+class StaleHostResolverTest : public testing::Test {
+ protected:
+  StaleHostResolverTest()
+      : mock_proc_(new MockHostResolverProc()),
+        resolver_(nullptr),
+        resolve_pending_(false),
+        resolve_complete_(false) {}
+
+  ~StaleHostResolverTest() {}
+
+  void SetStaleDelay(int stale_delay_sec) {
+    DCHECK(!resolver_);
+
+    options_.delay = base::TimeDelta::FromSeconds(stale_delay_sec);
+  }
+
+  void SetStaleUsability(int max_expired_time_sec,
+                         int max_stale_uses,
+                         bool allow_other_network) {
+    DCHECK(!resolver_);
+
+    options_.max_expired_time =
+        base::TimeDelta::FromSeconds(max_expired_time_sec);
+    options_.max_stale_uses = max_stale_uses;
+    options_.allow_other_network = allow_other_network;
+  }
+
+  void CreateResolver() {
+    DCHECK(!resolver_);
+
+    std::unique_ptr<net::HostResolverImpl> inner_resolver(
+        net::HostResolver::CreateDefaultResolverImpl(nullptr));
+
+    net::HostResolverImpl::ProcTaskParams proc_params(mock_proc_.get(), 1u);
+    inner_resolver->set_proc_params_for_test(proc_params);
+
+    stale_resolver_ = base::WrapUnique(
+        new StaleHostResolver(std::move(inner_resolver), options_));
+    resolver_ = stale_resolver_.get();
+  }
+
+  void DestroyResolver() {
+    DCHECK(stale_resolver_);
+
+    stale_resolver_.reset();
+    resolver_ = nullptr;
+  }
+
+  void SetResolver(net::HostResolver* resolver) {
+    DCHECK(!resolver_);
+
+    resolver_ = resolver;
+  }
+
+  void ClearResolver() {
+    DCHECK(resolver_);
+    DCHECK(!stale_resolver_);
+
+    resolver_ = nullptr;
+  }
+
+  // Creates a cache entry for |kHostname| that is |age_sec| seconds old.
+  void CreateCacheEntry(int age_sec) {
+    DCHECK(resolver_);
+    DCHECK(resolver_->GetHostCache());
+
+    base::TimeDelta ttl(base::TimeDelta::FromSeconds(kCacheEntryTTLSec));
+    net::HostCache::Key key(kHostname, net::ADDRESS_FAMILY_IPV4, 0);
+    net::HostCache::Entry entry(net::OK, MakeAddressList(kCacheAddress), ttl);
+    base::TimeDelta age = base::TimeDelta::FromSeconds(age_sec);
+    base::TimeTicks then = base::TimeTicks::Now() - age;
+    resolver_->GetHostCache()->Set(key, entry, then, ttl);
+  }
+
+  void OnNetworkChange() {
+    DCHECK(resolver_);
+    DCHECK(resolver_->GetHostCache());
+
+    resolver_->GetHostCache()->OnNetworkChange();
+  }
+
+  void LookupStale() {
+    DCHECK(resolver_);
+    DCHECK(resolver_->GetHostCache());
+
+    net::HostCache::Key key(kHostname, net::ADDRESS_FAMILY_IPV4, 0);
+    base::TimeTicks now = base::TimeTicks::Now();
+    const net::HostCache::Entry* entry;
+    net::HostCache::EntryStaleness stale;
+    entry = resolver_->GetHostCache()->LookupStale(key, now, &stale);
+    EXPECT_TRUE(entry);
+    EXPECT_TRUE(stale.is_stale());
+  }
+
+  void Resolve() {
+    DCHECK(resolver_);
+    EXPECT_FALSE(resolve_pending_);
+
+    net::HostResolver::RequestInfo info(net::HostPortPair(kHostname, kPort));
+    info.set_address_family(net::ADDRESS_FAMILY_IPV4);
+
+    resolve_pending_ = true;
+    resolve_complete_ = false;
+    resolve_addresses_ = MakeAddressList(kUninitializedAddress);
+    resolve_error_ = net::ERR_UNEXPECTED;
+
+    int rv =
+        resolver_->Resolve(info, net::DEFAULT_PRIORITY, &resolve_addresses_,
+                           base::Bind(&StaleHostResolverTest::OnResolveComplete,
+                                      base::Unretained(this)),
+                           &request_, net::BoundNetLog());
+    if (rv != net::ERR_IO_PENDING) {
+      resolve_pending_ = false;
+      resolve_complete_ = true;
+      resolve_error_ = rv;
+    }
+  }
+
+  void WaitForResolve() {
+    if (!resolve_pending_)
+      return;
+
+    base::RunLoop run_loop;
+
+    // Run until resolve completes or timeout.
+    resolve_closure_ = run_loop.QuitWhenIdleClosure();
+    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+        FROM_HERE, run_loop.QuitWhenIdleClosure(),
+        base::TimeDelta::FromSeconds(kWaitTimeoutSec));
+    run_loop.Run();
+  }
+
+  void WaitForIdle() {
+    base::RunLoop run_loop;
+
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, run_loop.QuitWhenIdleClosure());
+    run_loop.Run();
+  }
+
+  void Cancel() {
+    DCHECK(resolver_);
+    EXPECT_TRUE(resolve_pending_);
+
+    delete request_.release();
+
+    resolve_pending_ = false;
+  }
+
+  void OnResolveComplete(int error) {
+    EXPECT_TRUE(resolve_pending_);
+
+    request_.reset();
+
+    resolve_error_ = error;
+    resolve_pending_ = false;
+    resolve_complete_ = true;
+
+    if (!resolve_closure_.is_null())
+      base::ResetAndReturn(&resolve_closure_).Run();
+  }
+
+  bool resolve_complete() const { return resolve_complete_; }
+  int resolve_error() const { return resolve_error_; }
+  const net::AddressList& resolve_addresses() const {
+    return resolve_addresses_;
+  }
+
+ private:
+  // Needed for HostResolver to run HostResolverProc callbacks.
+  base::MessageLoopForIO message_loop_for_io_;
+  scoped_refptr<MockHostResolverProc> mock_proc_;
+
+  net::HostResolver* resolver_;
+  StaleHostResolver::StaleOptions options_;
+  std::unique_ptr<StaleHostResolver> stale_resolver_;
+
+  base::TimeTicks now_;
+  std::unique_ptr<net::HostResolver::Request> request_;
+  bool resolve_pending_;
+  bool resolve_complete_;
+  net::AddressList resolve_addresses_;
+  int resolve_error_;
+
+  base::Closure resolve_closure_;
+};
+
+// Make sure that test harness can be created and destroyed without crashing.
+TEST_F(StaleHostResolverTest, Null) {}
+
+// Make sure that resolver can be created and destroyed without crashing.
+TEST_F(StaleHostResolverTest, Create) {
+  CreateResolver();
+}
+
+TEST_F(StaleHostResolverTest, Network) {
+  CreateResolver();
+
+  Resolve();
+  WaitForResolve();
+
+  EXPECT_TRUE(resolve_complete());
+  EXPECT_EQ(net::OK, resolve_error());
+  EXPECT_EQ(1u, resolve_addresses().size());
+  EXPECT_EQ(kNetworkAddress, resolve_addresses()[0].ToStringWithoutPort());
+}
+
+TEST_F(StaleHostResolverTest, FreshCache) {
+  CreateResolver();
+  CreateCacheEntry(kAgeFreshSec);
+
+  Resolve();
+
+  EXPECT_TRUE(resolve_complete());
+  EXPECT_EQ(net::OK, resolve_error());
+  EXPECT_EQ(1u, resolve_addresses().size());
+  EXPECT_EQ(kCacheAddress, resolve_addresses()[0].ToStringWithoutPort());
+
+  WaitForIdle();
+}
+
+TEST_F(StaleHostResolverTest, StaleCache) {
+  SetStaleDelay(kNoStaleDelaySec);
+  CreateResolver();
+  CreateCacheEntry(kAgeExpiredSec);
+
+  Resolve();
+  WaitForResolve();
+
+  EXPECT_TRUE(resolve_complete());
+  EXPECT_EQ(net::OK, resolve_error());
+  EXPECT_EQ(1u, resolve_addresses().size());
+  EXPECT_EQ(kCacheAddress, resolve_addresses()[0].ToStringWithoutPort());
+}
+
+TEST_F(StaleHostResolverTest, NetworkWithStaleCache) {
+  SetStaleDelay(kLongStaleDelaySec);
+  CreateResolver();
+  CreateCacheEntry(kAgeExpiredSec);
+
+  Resolve();
+  WaitForResolve();
+
+  EXPECT_TRUE(resolve_complete());
+  EXPECT_EQ(net::OK, resolve_error());
+  EXPECT_EQ(1u, resolve_addresses().size());
+  EXPECT_EQ(kNetworkAddress, resolve_addresses()[0].ToStringWithoutPort());
+}
+
+TEST_F(StaleHostResolverTest, CancelWithNoCache) {
+  SetStaleDelay(kNoStaleDelaySec);
+  CreateResolver();
+
+  Resolve();
+
+  Cancel();
+
+  EXPECT_FALSE(resolve_complete());
+
+  // Make sure there's no lingering |OnResolveComplete()| callback waiting.
+  WaitForIdle();
+}
+
+TEST_F(StaleHostResolverTest, CancelWithStaleCache) {
+  SetStaleDelay(kLongStaleDelaySec);
+  CreateResolver();
+  CreateCacheEntry(kAgeExpiredSec);
+
+  Resolve();
+
+  Cancel();
+
+  EXPECT_FALSE(resolve_complete());
+
+  // Make sure there's no lingering |OnResolveComplete()| callback waiting.
+  WaitForIdle();
+}
+
+// CancelWithFreshCache makes no sense; the request would've returned
+// synchronously.
+
+TEST_F(StaleHostResolverTest, StaleUsability) {
+  const struct {
+    int max_expired_time_sec;
+    int max_stale_uses;
+    bool allow_other_network;
+
+    int age_sec;
+    int stale_use;
+    int network_changes;
+
+    bool usable;
+  } kUsabilityTestCases[] = {
+      // Fresh data always accepted.
+      {0, 0, true, -1, 1, 0, true},
+      {1, 1, false, -1, 1, 0, true},
+
+      // Unlimited expired time accepts non-zero time.
+      {0, 0, true, 1, 1, 0, true},
+
+      // Limited expired time accepts before but not after limit.
+      {2, 0, true, 1, 1, 0, true},
+      {2, 0, true, 3, 1, 0, false},
+
+      // Unlimited stale uses accepts first and later uses.
+      {2, 0, true, 1, 1, 0, true},
+      {2, 0, true, 1, 9, 0, true},
+
+      // Limited stale uses accepts up to and including limit.
+      {2, 2, true, 1, 1, 0, true},
+      {2, 2, true, 1, 2, 0, true},
+      {2, 2, true, 1, 3, 0, false},
+      {2, 2, true, 1, 9, 0, false},
+
+      // Allowing other networks accepts zero or more network changes.
+      {2, 0, true, 1, 1, 0, true},
+      {2, 0, true, 1, 1, 1, true},
+      {2, 0, true, 1, 1, 9, true},
+
+      // Disallowing other networks only accepts zero network changes.
+      {2, 0, false, 1, 1, 0, true},
+      {2, 0, false, 1, 1, 1, false},
+      {2, 0, false, 1, 1, 9, false},
+  };
+
+  SetStaleDelay(kNoStaleDelaySec);
+
+  for (size_t i = 0; i < arraysize(kUsabilityTestCases); ++i) {
+    const auto& test_case = kUsabilityTestCases[i];
+
+    SetStaleUsability(test_case.max_expired_time_sec, test_case.max_stale_uses,
+                      test_case.allow_other_network);
+    CreateResolver();
+    CreateCacheEntry(kCacheEntryTTLSec + test_case.age_sec);
+    for (int j = 0; j < test_case.network_changes; ++j)
+      OnNetworkChange();
+    for (int j = 0; j < test_case.stale_use - 1; ++j)
+      LookupStale();
+
+    Resolve();
+    WaitForResolve();
+    EXPECT_TRUE(resolve_complete()) << i;
+    EXPECT_EQ(net::OK, resolve_error()) << i;
+    EXPECT_EQ(1u, resolve_addresses().size()) << i;
+    {
+      const char* expected = test_case.usable ? kCacheAddress : kNetworkAddress;
+      EXPECT_EQ(expected, resolve_addresses()[0].ToStringWithoutPort()) << i;
+    }
+
+    DestroyResolver();
+  }
+}
+
+TEST_F(StaleHostResolverTest, CreatedByContext) {
+  URLRequestContextConfig config(
+      // Enable QUIC.
+      true,
+      // QUIC User Agent ID.
+      "Default QUIC User Agent ID",
+      // Enable SPDY.
+      true,
+      // Enable SDCH.
+      false,
+      // Type of http cache.
+      URLRequestContextConfig::HttpCacheType::DISK,
+      // Max size of http cache in bytes.
+      1024000,
+      // Disable caching for HTTP responses. Other information may be stored in
+      // the cache.
+      false,
+      // Storage path for http cache and cookie storage.
+      "/data/data/org.chromium.net/app_cronet_test/test_storage",
+      // User-Agent request header field.
+      "fake agent",
+      // JSON encoded experimental options.
+      "{\"AsyncDNS\":{\"enable\":false},"
+      "\"StaleDNS\":{\"enable\":true,"
+      "\"delay_ms\":0,"
+      "\"max_expired_time_ms\":0,"
+      "\"max_stale_uses\":0}}",
+      // Data reduction proxy key.
+      "",
+      // Data reduction proxy.
+      "",
+      // Fallback data reduction proxy.
+      "",
+      // Data reduction proxy secure proxy check URL.
+      "",
+      // MockCertVerifier to use for testing purposes.
+      std::unique_ptr<net::CertVerifier>(),
+      // Enable network quality estimator.
+      false,
+      // Enable Public Key Pinning bypass for local trust anchors.
+      true,
+      // Certificate verifier cache data.
+      "");
+
+  net::URLRequestContextBuilder builder;
+  net::NetLog net_log;
+  config.ConfigureURLRequestContextBuilder(&builder, &net_log, nullptr);
+  // Set a ProxyConfigService to avoid DCHECK failure when building.
+  builder.set_proxy_config_service(base::WrapUnique(
+      new net::ProxyConfigServiceFixed(net::ProxyConfig::CreateDirect())));
+  std::unique_ptr<net::URLRequestContext> context(builder.Build());
+
+  // Duplicate StaleCache test case to ensure StaleHostResolver was created:
+
+  // Note: Experimental config above sets 0ms stale delay.
+  SetResolver(context->host_resolver());
+  CreateCacheEntry(kAgeExpiredSec);
+
+  Resolve();
+  EXPECT_FALSE(resolve_complete());
+  WaitForResolve();
+
+  EXPECT_TRUE(resolve_complete());
+  EXPECT_EQ(net::OK, resolve_error());
+  EXPECT_EQ(1u, resolve_addresses().size());
+  EXPECT_EQ(kCacheAddress, resolve_addresses()[0].ToStringWithoutPort());
+}
+
+}  // namespace
+
+}  // namespace cronet