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

net/dns/dns_test_util.cc

+// 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.
+
+#include <netinet/in.h>
+
+#include <string>
+
+#include "base/bind.h"
+#include "base/memory/weak_ptr.h"
+#include "base/message_loop.h"
+#include "net/base/big_endian.h"
+#include "net/base/dns_util.h"
+#include "net/base/io_buffer.h"
+#include "net/base/net_errors.h"
+#include "net/dns/dns_client.h"
+#include "net/dns/dns_config_service.h"
+#include "net/dns/dns_protocol.h"
+#include "net/dns/dns_query.h"
+#include "net/dns/dns_response.h"
+#include "net/dns/dns_transaction.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+
+// A DnsTransactionFactory which responds with 127.0.0.1 to all queries
+// starting with "ok", fails synchronously on all queries starting with "er",
+// and NXDOMAIN to all others.
+class MockTransactionFactory : public DnsTransactionFactory {

[mmenke, 2012/03/12 16:23:31]

nit:  This should all be in an anonymous namespace, except for
CreateMockDnsClient.

+ public:
+  // Using WeakPtr to support cancellation.
+  class MockTransaction : public DnsTransaction,
+                          public base::SupportsWeakPtr<MockTransaction> {

[mmenke, 2012/03/12 16:23:31]

nit:  To make the code a little easier to follow, I suggest you move this inner
class outside of MockTransactionFactory (Or don't inline the functions).

+   public:
+    MockTransaction(const std::string& hostname,
+                    uint16 qtype,
+                    const DnsTransactionFactory::CallbackType& callback)
+        : hostname_(hostname),
+          qtype_(qtype),
+          callback_(callback),
+          started_(false) {
+    }
+
+    virtual const std::string& GetHostname() const OVERRIDE {
+      return hostname_;
+    }
+
+    virtual uint16 GetType() const OVERRIDE {
+      return qtype_;
+    }
+
+    virtual int Start() OVERRIDE {
+      EXPECT_FALSE(started_);
+      started_ = true;
+      if (hostname_.substr(0, 2) == "er")
+        return ERR_NAME_NOT_RESOLVED;
+      MessageLoop::current()->PostTask(
+          FROM_HERE,
+          base::Bind(&MockTransaction::Finish, AsWeakPtr()));
+      return ERR_IO_PENDING;
+    }
+
+   private:
+    void Finish() {
+      if (hostname_.substr(0, 2) == "ok") {
+        std::string qname;
+        DNSDomainFromDot(hostname_, &qname);
+        DnsQuery query(0, qname, qtype_);
+
+        DnsResponse response;
+        char* buffer = response.io_buffer()->data();
+        int nbytes = query.io_buffer()->size();
+        memcpy(buffer, query.io_buffer()->data(), nbytes);
+        reinterpret_cast<dns_protocol::Header*>(buffer)->ancount = htons(1);
+
+        const uint16 kPointerToQueryName =
+            static_cast<uint16>(0xc000 | sizeof(net::dns_protocol::Header));
+
+        const uint32 kTTL = 86400;  // One day.
+
+        // Size of RDATA which is a IPv4 or IPv6 address.
+        size_t rdata_size = qtype_ == net::dns_protocol::kTypeA ?
+                            net::kIPv4AddressSize : net::kIPv6AddressSize;
+
+        // 12 is the sum of sizes of the compressed name reference, TYPE,
+        // CLASS, TTL and RDLENGTH.
+        size_t answer_size = 12 + rdata_size;
+
+        // Write 127.0.0.1 answer

[mmenke, 2012/03/12 16:23:31]

nit:  Suggest you say "loopback address", since IPv6 is supported.

+        BigEndianWriter writer(buffer + nbytes, answer_size);
+        writer.WriteU16(kPointerToQueryName);
+        writer.WriteU16(qtype_);
+        writer.WriteU16(net::dns_protocol::kClassIN);
+        writer.WriteU32(kTTL);
+        writer.WriteU16(rdata_size);
+        if (qtype_ == net::dns_protocol::kTypeA)
+          writer.WriteU32(INADDR_LOOPBACK);
+        else
+          writer.WriteBytes(&in6addr_loopback, sizeof(in6_addr));
+
+        EXPECT_TRUE(response.InitParse(nbytes + answer_size, query));
+        callback_.Run(this, OK, &response);
+      } else {
+        callback_.Run(this, ERR_NAME_NOT_RESOLVED, NULL);
+      }
+    }
+
+    const std::string hostname_;
+    const uint16 qtype_;
+    DnsTransactionFactory::CallbackType callback_;
+    bool started_;
+  };
+
+  typedef std::pair<std::string, uint16> Key;
+
+  MockTransactionFactory() : num_requests_(0) {}
+  virtual ~MockTransactionFactory() {}
+
+  virtual scoped_ptr<DnsTransaction> CreateTransaction(
+      const std::string& hostname,
+      uint16 qtype,
+      const DnsTransactionFactory::CallbackType& callback,
+      const BoundNetLog&) OVERRIDE {
+    ++num_requests_;
+    return scoped_ptr<DnsTransaction>(
+        new MockTransaction(hostname, qtype, callback));
+  }
+
+  int num_requests() const { return num_requests_; }
+
+ private:
+  int num_requests_;
+};
+
+// MockDnsClient provides MockTransactionFactory.
+class MockDnsClient : public DnsClient {
+ public:
+  virtual ~MockDnsClient() {}
+
+  virtual void SetConfig(const DnsConfig& config) OVERRIDE {
+    config_ = config;
+  }
+
+  virtual const DnsConfig* GetConfig() const OVERRIDE {
+    return config_.IsValid() ? &config_ : NULL;
+  }
+
+  virtual DnsTransactionFactory* GetTransactionFactory() OVERRIDE {
+    return &factory_;
+  }
+
+ private:
+  DnsConfig config_;
+  MockTransactionFactory factory_;
+};
+
+
+// static
+scoped_ptr<DnsClient> CreateMockDnsClient() {
+  return scoped_ptr<DnsClient>(new MockDnsClient());
+}
+
+}  // namespace net