[net/dns] Serve requests from HOSTS file if possible.

net/base/host_resolver_impl.h

 // Copyright (c) 2012 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.
 
 #ifndef NET_BASE_HOST_RESOLVER_IMPL_H_
 #define NET_BASE_HOST_RESOLVER_IMPL_H_
 #pragma once
 
 #include <map>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/time.h"
 #include "net/base/capturing_net_log.h"
 #include "net/base/host_cache.h"
 #include "net/base/host_resolver.h"
 #include "net/base/host_resolver_proc.h"
 #include "net/base/net_export.h"
 #include "net/base/net_log.h"
 #include "net/base/network_change_notifier.h"
 #include "net/base/prioritized_dispatcher.h"
+#include "net/dns/dns_client.h"
 #include "net/dns/dns_config_service.h"
 
 namespace net {
 
-class DnsTransactionFactory;
-
 // For each hostname that is requested, HostResolver creates a
 // HostResolverImpl::Job. When this job gets dispatched it creates a ProcTask
 // which runs the given HostResolverProc on a WorkerPool thread. If requests for
 // that same host are made during the job's lifetime, they are attached to the
 // existing job rather than creating a new one. This avoids doing parallel
 // resolves for the same host.
 //
 // The way these classes fit together is illustrated by:
 //
 //
@@ skipping 105 matching lines @@
   virtual AddressFamily GetDefaultAddressFamily() const OVERRIDE;
   virtual void ProbeIPv6Support() OVERRIDE;
   virtual HostCache* GetHostCache() OVERRIDE;
 
   // Allows the tests to catch slots leaking out of the dispatcher.
   size_t num_running_jobs_for_tests() const {
     return dispatcher_.num_running_jobs();
   }
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(HostResolverImplTest, DnsTask);
+  FRIEND_TEST_ALL_PREFIXES(HostResolverImplTest, ServeFromHosts);
   class Job;
   class ProcTask;
   class IPv6ProbeJob;
   class DnsTask;
   class Request;
   typedef HostCache::Key Key;
   typedef std::map<Key, Job*> JobMap;
   typedef std::vector<Request*> RequestsList;
 
+  void set_dns_client_for_tests(scoped_ptr<DnsClient> client) {
+    dns_client_ = client.Pass();
+  }
+
   // Helper used by |Resolve()| and |ResolveFromCache()|.  Performs IP
-  // literal and cache lookup, returns OK if successful,
+  // literal, cache and HOSTS lookup (if enabled), returns OK if successful,
   // ERR_NAME_NOT_RESOLVED if either hostname is invalid or IP literal is
-  // incompatible, ERR_DNS_CACHE_MISS if entry was not found in cache.
+  // incompatible, ERR_DNS_CACHE_MISS if entry was not found in cache and HOSTS.
   int ResolveHelper(const Key& key,
                     const RequestInfo& info,
                     AddressList* addresses,
                     const BoundNetLog& request_net_log);
 
   // Tries to resolve |key| as an IP, returns true and sets |net_error| if
   // succeeds, returns false otherwise.
   bool ResolveAsIP(const Key& key,
                    const RequestInfo& info,
                    int* net_error,
                    AddressList* addresses);
 
   // If |key| is not found in cache returns false, otherwise returns
   // true, sets |net_error| to the cached error code and fills |addresses|
   // if it is a positive entry.
   bool ServeFromCache(const Key& key,
                       const RequestInfo& info,
-                      const BoundNetLog& request_net_log,
                       int* net_error,
                       AddressList* addresses);
 
+  // If |key| is not found in the HOSTS file or no HOSTS file known, returns
+  // false, otherwise returns true and fills |addresses|.
+  bool ServeFromHosts(const Key& key,
+                      const RequestInfo& info,
+                      AddressList* addresses);
+
   // Notifies IPv6ProbeJob not to call back, and discard reference to the job.
   void DiscardIPv6ProbeJob();
 
   // Callback from IPv6 probe activity.
   void IPv6ProbeSetDefaultAddressFamily(AddressFamily address_family);
 
   // Returns the (hostname, address_family) key to use for |info|, choosing an
   // "effective" address family by inheriting the resolver's default address
   // family when the request leaves it unspecified.
   Key GetEffectiveKeyForRequest(const RequestInfo& info) const;
 
   // Records the result in cache if cache is present.
   void CacheResult(const Key& key,
                    int net_error,
                    const AddressList& addr_list,
                    base::TimeDelta ttl);
 
   // Removes |job| from |jobs_|, only if it exists.
   void RemoveJob(Job* job);
 
   // Aborts all in progress jobs and notifies their requests.
   // Might start new jobs.
   void AbortAllInProgressJobs();
 
+  // Attempts to serve each Job in |jobs_| from the HOSTS file.
+  void TryServingAllJobsFromHosts();
+
   // NetworkChangeNotifier::IPAddressObserver:
   virtual void OnIPAddressChanged() OVERRIDE;
 
   // NetworkChangeNotifier::DNSObserver:
   virtual void OnDNSChanged(unsigned detail) OVERRIDE;
 
   // DnsConfigService::Observer:
   virtual void OnConfigChanged(const DnsConfig& dns_config) OVERRIDE;
 
+  // True if have fully configured DNS client.
+  bool HaveDnsConfig() const;
+
   // Cache of host resolution results.
   scoped_ptr<HostCache> cache_;
 
   // Map from HostCache::Key to a Job.
   JobMap jobs_;
 
   // Starts Jobs according to their priority and the configured limits.
   PrioritizedDispatcher dispatcher_;
 
   // Limit on the maximum number of jobs queued in |dispatcher_|.
   size_t max_queued_jobs_;
 
   // Parameters for ProcTask.
   ProcTaskParams proc_params_;
 
-  scoped_ptr<DnsTransactionFactory> dns_transaction_factory_;
-
   // Address family to use when the request doesn't specify one.
   AddressFamily default_address_family_;
 
+  scoped_ptr<DnsClient> dns_client_;
   scoped_ptr<DnsConfigService> dns_config_service_;
 
   // Indicate if probing is done after each network change event to set address
   // family.
   // When false, explicit setting of address family is used.
   bool ipv6_probe_monitoring_;
 
   // The last un-cancelled IPv6ProbeJob (if any).
   scoped_refptr<IPv6ProbeJob> ipv6_probe_job_;
 
   // Any resolver flags that should be added to a request by default.
   HostResolverFlags additional_resolver_flags_;
 
   NetLog* net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(HostResolverImpl);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_HOST_RESOLVER_IMPL_H_