HostResolver: don't interpret NULL callback argument as a request to do synchronous resolution.

net/base/host_resolver_impl.h

 // 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.
 
 #ifndef NET_BASE_HOST_RESOLVER_IMPL_H_
 #define NET_BASE_HOST_RESOLVER_IMPL_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 119 matching lines @@
   //                            ERR_HOST_RESOLVER_QUEUE_TOO_LARGE.
   void SetPoolConstraints(JobPoolIndex pool_index,
                           size_t max_outstanding_jobs,
                           size_t max_pending_requests);
 
   // HostResolver methods:
   virtual int Resolve(const RequestInfo& info,
                       AddressList* addresses,
                       CompletionCallback* callback,
                       RequestHandle* out_req,
-                      const BoundNetLog& source_net_log);
-  virtual void CancelRequest(RequestHandle req);
-  virtual void AddObserver(HostResolver::Observer* observer);
-  virtual void RemoveObserver(HostResolver::Observer* observer);
+                      const BoundNetLog& source_net_log) OVERRIDE;
+  virtual int ResolveFromCache(const RequestInfo& info,
+                               AddressList* addresses,
+                               const BoundNetLog& source_net_log) OVERRIDE;
+  virtual void CancelRequest(RequestHandle req) OVERRIDE;
+  virtual void AddObserver(HostResolver::Observer* observer) OVERRIDE;
+  virtual void RemoveObserver(HostResolver::Observer* observer) OVERRIDE;
 
   // Set address family, and disable IPv6 probe support.
-  virtual void SetDefaultAddressFamily(AddressFamily address_family);
-  virtual AddressFamily GetDefaultAddressFamily() const;
+  virtual void SetDefaultAddressFamily(AddressFamily address_family) OVERRIDE;
+  virtual AddressFamily GetDefaultAddressFamily() const OVERRIDE;
 
-  virtual HostResolverImpl* GetAsHostResolverImpl();
+  virtual HostResolverImpl* GetAsHostResolverImpl() OVERRIDE;
 
  private:
   // Allow tests to access our innards for testing purposes.
   friend class LookupAttemptHostResolverProc;
 
   // Allow tests to access our innards for testing purposes.
   FRIEND_TEST_ALL_PREFIXES(HostResolverImplTest, MultipleAttempts);
 
   class Job;
   class JobPool;
   class IPv6ProbeJob;
   class Request;
   typedef std::vector<Request*> RequestsList;
   typedef HostCache::Key Key;
   typedef std::map<Key, scoped_refptr<Job> > JobMap;
   typedef std::vector<HostResolver::Observer*> ObserversList;
 
+  // Helper used by |Resolve()| and |ResolveFromCache()|.  Performs IP
+  // literal and cache lookup, returns OK if successfull,
+  // 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.
+  int ResolveHelper(int request_id,
+                    const Key& key,
+                    const RequestInfo& info,
+                    AddressList* addresses,
+                    const BoundNetLog& request_net_log,
+                    const BoundNetLog& source_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);
+
   // Returns the HostResolverProc to use for this instance.
   HostResolverProc* effective_resolver_proc() const {
     return resolver_proc_ ?
         resolver_proc_.get() : HostResolverProc::GetDefault();
   }
 
   // Adds a job to outstanding jobs list.
   void AddOutstandingJob(Job* job);
 
   // Returns the outstanding job for |key|, or NULL if there is none.
@@ skipping 157 matching lines @@
   HostResolverFlags additional_resolver_flags_;
 
   NetLog* net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(HostResolverImpl);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_HOST_RESOLVER_IMPL_H_