Added DnsQuery class

net/base/dns_response.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_DNS_RESPONSE_H_
+#define NET_BASE_DNS_RESPONSE_H_
+#pragma once
+
+#include "net/base/dns_query.h"
+
+namespace net{
+
+class AddressList;
+
+// A class that encapsulates bits and pieces related to DNS response
+// processing.
+class DnsResponse {

[cbentzel, 2011/06/01 17:17:03]

DnsResponse is a bit different than I expected. I thought it was going to just
parse the bytes over the network, determine if it's valid syntax, and add API's
for extracting RR's etc.

Then, a higher level function/class would determine whether it's a valid
response for the query.

However, I haven't seen this used yet. On it's own it seems fine, but I may ask
for the class design to change once I see it in use.

+ public:
+  // Constructs a response object with an IOBuffer large enough to read
+  // every possible; |query| is a pointer to the DnsQuery for which |this|
+  // is supposed to be a response.
+  DnsResponse(DnsQuery* query);

[cbentzel, 2011/06/01 17:17:03]

Mark this constructor as explicit.

[cbentzel, 2011/06/01 17:17:03]

You should specify what the lifetime expectations are for |query| - does
DNSResponse own it, should it last longer, etc.

[agayev, 2011/06/01 19:15:01]

Done.

+
+  // Internal buffer accessor into which actual bytes of response to be
+  // read.
+  IOBuffer* io_buffer() { return io_buffer_.get(); }
+
+  // Returns the size of the DNS response.
+  int size() const { return size_; }
+
+  // Parses response of size nbytes and puts address into |results|,
+  // returns whether succeeded or not.
+  bool Parse(int nbytes, AddressList* results);
+
+  // Error code accessor.
+  int error() const { return error_; }
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(DnsResponseTest, ResponseWithCnameA);
+
+  // Gives access to the response bytes directly, used by tests.
+  char* data() { return io_buffer_->data(); }
+
+  // Error code, currently either 0 or EAI_NONAME, will be amended with
+  // specific error codes in the future.
+  int error_;
+
+  // Size of the response; initially it is one byte larger than maximum DNS
+  // response size to allow reading all possible responses as well as
+  // detecting oversized ones, adjusted once the actual response is read.
+  int size_;
+
+  // The matching query; |this| is the response for this query.
+  DnsQuery* const query_;
+
+  // Buffer into which response bytes are read.
+  scoped_refptr<IOBufferWithSize> io_buffer_;
+
+  DISALLOW_COPY_AND_ASSIGN(DnsResponse);
+};
+
+}  // namespace net
+
+#endif  // NET_BASE_DNS_RESPONSE_H_