Refactorings surrounding HostResolver:...

net/base/mock_host_resolver.h

-// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2009 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_UNITTEST_H_
-#define NET_BASE_HOST_RESOLVER_UNITTEST_H_
-
-#ifdef UNIT_TEST
+#ifndef NET_BASE_MOCK_HOST_RESOLVER_H_
+#define NET_BASE_MOCK_HOST_RESOLVER_H_
 
 #include <list>
 
-#include "base/string_util.h"
-#include "base/platform_thread.h"
-#include "base/ref_counted.h"
 #include "base/waitable_event.h"
-#include "net/base/host_resolver.h"
-#include "net/base/net_errors.h"
+#include "net/base/host_resolver_impl.h"
+#include "net/base/host_resolver_proc.h"
 
 namespace net {
 
+class RuleBasedHostResolverProc;
+
 // In most cases, it is important that unit tests avoid making actual DNS
 // queries since the resulting tests can be flaky, especially if the network is
 // unreliable for some reason.  To simplify writing tests that avoid making
-// actual DNS queries, the following helper class may be used:
+// actual DNS queries, pass a MockHostResolver as the HostResolver dependency.
+// The socket addresses returned can be configured using the
+// RuleBasedHostResolverProc:
 //
-//   scoped_refptr<RuleBasedHostMapper> host_mapper = new RuleBasedHostMapper();
-//   host_mapper->AddRule("foo.com", "1.2.3.4");
-//   host_mapper->AddRule("bar.com", "2.3.4.5");
-//
-// Don't forget to actually set your mapper, probably with ScopedHostMapper!
+//   host_resolver->rules()->AddRule("foo.com", "1.2.3.4");
+//   host_resolver->rules()->AddRule("bar.com", "2.3.4.5");
 //
 // The above rules define a static mapping from hostnames to IP address
 // literals.  The first parameter to AddRule specifies a host pattern to match
 // against, and the second parameter indicates what value should be used to
 // replace the given hostname.  So, the following is also supported:
 //
 //   host_mapper->AddRule("*.com", "127.0.0.1");
 //
 // Replacement doesn't have to be string representing an IP address. It can
 // re-map one hostname to another as well.
-class RuleBasedHostMapper : public HostMapper {
+class MockHostResolver : public HostResolver {
  public:
+  // Creates a MockHostResolver that does NOT cache entries
+  // (the HostResolverProc will be called for every lookup). If you need
+  // caching behavior, call Reset() with non-zero cache size.
+  MockHostResolver();
+
+  virtual ~MockHostResolver() {}
+
+  // HostResolver methods:
+  virtual int Resolve(const RequestInfo& info, AddressList* addresses,
+                      CompletionCallback* callback, RequestHandle* out_req);
+  virtual void CancelRequest(RequestHandle req);
+  virtual void AddObserver(Observer* observer);
+  virtual void RemoveObserver(Observer* observer);
+  // TODO(eroman): temp hack for http://crbug.com/15513
+  virtual void Shutdown();
+
+  RuleBasedHostResolverProc* rules() { return rules_; }
+
+  // Resets the mock.
+  void Reset(HostResolverProc* interceptor,
+             int max_cache_entries,
+             int max_cache_age_ms);
+
+ private:
+  scoped_refptr<HostResolverImpl> impl_;
+  scoped_refptr<RuleBasedHostResolverProc> rules_;
+};
+
+// RuleBasedHostResolverProc applies a set of rules to map a host string to
+// a replacement host string. It then uses the system host resolver to return
+// a socket address. Generally the replacement should be an IPv4 literal so
+// there is no network dependency.
+class RuleBasedHostResolverProc : public HostResolverProc {
+ public:
+  explicit RuleBasedHostResolverProc(HostResolverProc* previous);
+  ~RuleBasedHostResolverProc();
+
   // Any hostname matching the given pattern will be replaced with the given
   // replacement value.  Usually, replacement should be an IP address literal.
-  void AddRule(const char* host_pattern, const char* replacement) {
-    rules_.push_back(Rule(host_pattern, replacement));
-  }
+  void AddRule(const std::string& host_pattern,
+               const std::string& replacement);
 
-  void AddRuleWithLatency(const char* host_pattern, const char* replacement,
-                          int latency) {
-    rules_.push_back(Rule(host_pattern, replacement, latency));
-  }
+  void AddRuleWithLatency(const std::string& host_pattern,
+                          const std::string& replacement,
+                          int latency_ms);
 
   // Make sure that |host| will not be re-mapped or even processed by underlying
-  // host mappers. It can also be a pattern.
-  void AllowDirectLookup(const char* host) {
-    rules_.push_back(Rule(host, "", true));
-  }
+  // host resolver procedures. It can also be a pattern.
+  void AllowDirectLookup(const std::string& host);
 
   // Simulate a lookup failure for |host| (it also can be a pattern).
-  void AddSimulatedFailure(const char* host) {
-    AddRule(host, "");
-  }
+  void AddSimulatedFailure(const std::string& host);
 
-  virtual std::string Map(const std::string& host) {
-    RuleList::iterator r;
-    for (r = rules_.begin(); r != rules_.end(); ++r) {
-      if (MatchPattern(host, r->host_pattern)) {
-        if (r->latency != 0) {
-          PlatformThread::Sleep(r->latency);
-          r->latency = 1;  // Simulate cache warmup.
-        }
-        return r->direct ? host : r->replacement;
-      }
-    }
-
-    return MapUsingPrevious(host);
-  }
+  // HostResolverProc methods:
+  virtual int Resolve(const std::string& host, AddressList* addrlist);
 
  private:
-  struct Rule {
-    std::string host_pattern;
-    std::string replacement;
-    int latency;  // in milliseconds
-    bool direct;  // if true, don't mangle hostname and ignore replacement
-    Rule(const char* h, const char* r)
-        : host_pattern(h),
-          replacement(r),
-          latency(0),
-          direct(false) {}
-    Rule(const char* h, const char* r, const int l)
-        : host_pattern(h),
-          replacement(r),
-          latency(l),
-          direct(false) {}
-    Rule(const char* h, const char* r, const bool d)
-        : host_pattern(h),
-          replacement(r),
-          latency(0),
-          direct(d) {}
-  };
+  struct Rule;
   typedef std::list<Rule> RuleList;
   RuleList rules_;
 };
 
-// Using WaitingHostMapper you can simulate very long lookups, for example
-// to test code which cancels a request. Example usage:
-//
-//   scoped_refptr<WaitingHostMapper> mapper = new WaitingHostMapper();
-//   ScopedHostMapper scoped_mapper(mapper.get());
-//
-//   (start the lookup asynchronously)
-//   (cancel the lookup)
-//
-//   mapper->Signal();
-class WaitingHostMapper : public HostMapper {
+// Using WaitingHostResolverProc you can simulate very long lookups.
+class WaitingHostResolverProc : public HostResolverProc {
  public:
-  WaitingHostMapper() : event_(false, false) {
-  }
+  explicit WaitingHostResolverProc(HostResolverProc* previous)
+      : HostResolverProc(previous), event_(false, false) {}
 
   void Signal() {
     event_.Signal();
   }
 
- private:
-  virtual std::string Map(const std::string& host) {
+  // HostResolverProc methods:
+  virtual int Resolve(const std::string& host, AddressList* addrlist) {
     event_.Wait();
-    return MapUsingPrevious(host);
+    return ResolveUsingPrevious(host, addrlist);
   }
 
   base::WaitableEvent event_;
 };
 
-// This class sets the HostMapper for a particular scope. If there are multiple
-// ScopedHostMappers in existence, then the last one allocated will be used.
-// However, if it does not provide a matching rule, then it should delegate
-// to the previously set HostMapper (see SetHostMapper). This is true for all
-// mappers defined in this file. If no HostMapper matches a given hostname, then
-// the hostname will be unmodified.
-class ScopedHostMapper {
+// This class sets the HostResolverProc for a particular scope. If there are
+// multiple ScopedDefaultHostResolverProc in existence, then the last one
+// allocated will be used. However, if it does not provide a matching rule,
+// then it should delegate to the previously set HostResolverProc.
+//
+// NOTE: Only use this as a catch-all safety net. Individual tests should use
+// MockHostResolver.
+class ScopedDefaultHostResolverProc {
  public:
-  ScopedHostMapper(HostMapper* mapper) : current_host_mapper_(mapper) {
-    previous_host_mapper_ = SetHostMapper(current_host_mapper_.get());
-    current_host_mapper_->set_previous_mapper(previous_host_mapper_.get());
-  }
+  ScopedDefaultHostResolverProc() {}
+  explicit ScopedDefaultHostResolverProc(HostResolverProc* proc);
 
-  ScopedHostMapper() {}
+  ~ScopedDefaultHostResolverProc();
 
-  ~ScopedHostMapper() {
-    HostMapper* old_mapper = SetHostMapper(previous_host_mapper_.get());
-    // The lifetimes of multiple instances must be nested.
-    CHECK(old_mapper == current_host_mapper_.get());
-  }
-
-  void Init(HostMapper* mapper) {
-    current_host_mapper_ = mapper;
-    previous_host_mapper_ = SetHostMapper(current_host_mapper_.get());
-    current_host_mapper_->set_previous_mapper(previous_host_mapper_.get());
-  }
+  void Init(HostResolverProc* proc);
 
  private:
-  scoped_refptr<HostMapper> current_host_mapper_;
-  scoped_refptr<HostMapper> previous_host_mapper_;
+  scoped_refptr<HostResolverProc> current_proc_;
+  scoped_refptr<HostResolverProc> previous_proc_;
 };
 
 }  // namespace net
 
-#endif  // UNIT_TEST
-
-#endif  // NET_BASE_HOST_RESOLVER_UNITTEST_H_
+#endif  // NET_BASE_MOCK_HOST_RESOLVER_H_