Refactorings surrounding HostResolver:...

net/base/mock_host_resolver.cc

-// 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
-
-#include <list>
+#include "net/base/mock_host_resolver.h"
 
 #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"
 
 namespace net {
 
-// 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:
-//
-//   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!
-//
-// 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 {
- public:
-  // 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));
+MockHostResolver::MockHostResolver() {
+  Reset(NULL, 0, 0);
+}
+
+int MockHostResolver::Resolve(const RequestInfo& info,
+                              AddressList* addresses,
+                              CompletionCallback* callback,
+                              RequestHandle* out_req) {
+  return impl_->Resolve(info, addresses, callback, out_req);
+}
+
+void MockHostResolver::CancelRequest(RequestHandle req) {
+  impl_->CancelRequest(req);
+}
+
+void MockHostResolver::AddObserver(Observer* observer) {
+  impl_->AddObserver(observer);
+}
+
+void MockHostResolver::RemoveObserver(Observer* observer) {
+  impl_->RemoveObserver(observer);
+}
+
+void MockHostResolver::Shutdown() {
+  impl_->Shutdown();
+}
+
+void MockHostResolver::Reset(HostResolverProc* interceptor,
+                             int max_cache_entries,
+                             int max_cache_age_ms) {
+  // At the root of the chain, map everything to localhost.
+  scoped_refptr<RuleBasedHostResolverProc> catchall =
+      new RuleBasedHostResolverProc(NULL);
+  catchall->AddRule("*", "127.0.0.1");
+
+  // Next add a rules-based layer the use controls.
+  rules_ = new RuleBasedHostResolverProc(catchall);
+
+  HostResolverProc* proc = rules_;
+
+  // Lastly add the provided interceptor to the front of the chain.
+  if (interceptor) {
+    interceptor->set_previous_proc(proc);
+    proc = interceptor;
   }
 
-  void AddRuleWithLatency(const char* host_pattern, const char* replacement,
-                          int latency) {
-    rules_.push_back(Rule(host_pattern, replacement, latency));
-  }
+  impl_ = new HostResolverImpl(proc, max_cache_entries, max_cache_age_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));
-  }
+//-----------------------------------------------------------------------------
 
-  // Simulate a lookup failure for |host| (it also can be a pattern).
-  void AddSimulatedFailure(const char* host) {
-    AddRule(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);
-  }
-
- 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) {}
-  };
-  typedef std::list<Rule> RuleList;
-  RuleList rules_;
+struct RuleBasedHostResolverProc::Rule {
+  std::string host_pattern;
+  std::string replacement;
+  int latency_ms;  // In milliseconds.
+  bool direct;     // if true, don't mangle hostname and ignore replacement
+  Rule(const std::string& host_pattern, const std::string& replacement)
+      : host_pattern(host_pattern),
+        replacement(replacement),
+        latency_ms(0),
+        direct(false) {}
+  Rule(const std::string& host_pattern, const std::string& replacement,
+       const int latency_ms)
+      : host_pattern(host_pattern),
+        replacement(replacement),
+        latency_ms(latency_ms),
+        direct(false) {}
+  Rule(const std::string& host_pattern, const std::string& replacement,
+       const bool direct)
+      : host_pattern(host_pattern),
+        replacement(replacement),
+        latency_ms(0),
+        direct(direct) {}
 };
 
-// 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 {
- public:
-  WaitingHostMapper() : event_(false, false) {
+RuleBasedHostResolverProc::RuleBasedHostResolverProc(HostResolverProc* previous)
+    : HostResolverProc(previous) {
+}
+
+RuleBasedHostResolverProc::~RuleBasedHostResolverProc() {
+}
+
+void RuleBasedHostResolverProc::AddRule(const std::string& host_pattern,
+                                        const std::string& replacement) {
+  rules_.push_back(Rule(host_pattern, replacement));
+}
+
+void RuleBasedHostResolverProc::AddRuleWithLatency(
+    const std::string& host_pattern,
+    const std::string& replacement, int latency_ms) {
+  rules_.push_back(Rule(host_pattern, replacement, latency_ms));
+}
+
+void RuleBasedHostResolverProc::AllowDirectLookup(const std::string& host) {
+  rules_.push_back(Rule(host, "", true));
+}
+
+void RuleBasedHostResolverProc::AddSimulatedFailure(const std::string& host) {
+  AddRule(host, "");
+}
+
+int RuleBasedHostResolverProc::Resolve(const std::string& host,
+                                       AddressList* addrlist) {
+  RuleList::iterator r;
+  for (r = rules_.begin(); r != rules_.end(); ++r) {
+    if (MatchPattern(host, r->host_pattern)) {
+      if (r->latency_ms != 0) {
+        PlatformThread::Sleep(r->latency_ms);
+        // Hmm, this seems unecessary.
+        r->latency_ms = 1;
+      }
+      const std::string& effective_host = r->direct ? host : r->replacement;
+      if (effective_host.empty())
+        return ERR_NAME_NOT_RESOLVED;
+      return SystemHostResolverProc(effective_host, addrlist);
+    }
   }
+  return ResolveUsingPrevious(host, addrlist);
+}
 
-  void Signal() {
-    event_.Signal();
-  }
+//-----------------------------------------------------------------------------
 
- private:
-  virtual std::string Map(const std::string& host) {
-    event_.Wait();
-    return MapUsingPrevious(host);
-  }
+ScopedDefaultHostResolverProc::ScopedDefaultHostResolverProc(
+    HostResolverProc* proc) : current_proc_(proc) {
+  previous_proc_ = HostResolverProc::SetDefault(current_proc_);
+  current_proc_->set_previous_proc(previous_proc_);
+}
 
-  base::WaitableEvent event_;
-};
+ScopedDefaultHostResolverProc::~ScopedDefaultHostResolverProc() {
+  HostResolverProc* old_proc = HostResolverProc::SetDefault(previous_proc_);
+  // The lifetimes of multiple instances must be nested.
+  CHECK(old_proc == current_proc_);
+}
 
-// 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 {
- 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());
-  }
-
-  ScopedHostMapper() {}
-
-  ~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());
-  }
-
- private:
-  scoped_refptr<HostMapper> current_host_mapper_;
-  scoped_refptr<HostMapper> previous_host_mapper_;
-};
+void ScopedDefaultHostResolverProc::Init(HostResolverProc* proc) {
+  current_proc_ = proc;
+  previous_proc_ = HostResolverProc::SetDefault(current_proc_);
+  current_proc_->set_previous_proc(previous_proc_);
+}
 
 }  // namespace net
-
-#endif  // UNIT_TEST
-
-#endif  // NET_BASE_HOST_RESOLVER_UNITTEST_H_