Isolates generic DnsClient from AsyncHostResolver.

net/dns/dns_query.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_DNS_DNS_QUERY_H_
 #define NET_DNS_DNS_QUERY_H_
 #pragma once
 
-#include <string>
-
+#include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
+#include "base/string_piece.h"
 #include "net/base/net_export.h"
-#include "net/base/rand_callback.h"
 
 namespace net {
 
 class IOBufferWithSize;
 
 // Represents on-the-wire DNS query message as an object.
+// TODO(szym): add support for the OPT pseudo-RR (EDNS0/DNSSEC).
 class NET_EXPORT_PRIVATE DnsQuery {
  public:
   // Constructs a query message from |qname| which *MUST* be in a valid
-  // DNS name format, and |qtype| which must be either kDNS_A or kDNS_AAAA.
-
-  // Every generated object has a random ID, hence two objects generated
-  // with the same set of constructor arguments are generally not equal;
-  // there is a 1/2^16 chance of them being equal due to size of |id_|.
-  DnsQuery(const std::string& qname,
-           uint16 qtype,
-           const RandIntCallback& rand_int_cb);
+  // DNS name format, and |qtype|. The qclass is set to IN.
+  DnsQuery(uint16 id, const base::StringPiece& qname, uint16 qtype);
   ~DnsQuery();
 
-  // Clones |this| verbatim, with ID field of the header regenerated.
-  DnsQuery* CloneWithNewId() const;
+  // Clones |this| verbatim, with ID field of the header set to |id|.
+  DnsQuery* CloneWithNewId(uint16 id) const;
 
   // DnsQuery field accessors.
   uint16 id() const;
+  base::StringPiece qname() const;
   uint16 qtype() const;
 
-  // Returns the size of the Question section of the query.  Used when
-  // matching the response.
-  size_t question_size() const;
-
-  // Returns pointer to the Question section of the query.  Used when
-  // matching the response.
-  const char* question_data() const;
+  // Returns the Question section of the query.  Used when matching the
+  // response.
+  base::StringPiece question() const;
 
   // IOBuffer accessor to be used for writing out the query.
   IOBufferWithSize* io_buffer() const { return io_buffer_; }
 
  private:
-  const std::string qname() const;
-
-  // Randomizes ID field of the query message.
-  void RandomizeId();
+  DnsQuery(const DnsQuery& orig, uint16 id);
 
   // Size of the DNS name (*NOT* hostname) we are trying to resolve; used
   // to calculate offsets.
   size_t qname_size_;
 
   // Contains query bytes to be consumed by higher level Write() call.
   scoped_refptr<IOBufferWithSize> io_buffer_;
 
-  // PRNG function for generating IDs.
-  RandIntCallback rand_int_cb_;
-
   DISALLOW_COPY_AND_ASSIGN(DnsQuery);
 };
 
 }  // namespace net
 
 #endif  // NET_DNS_DNS_QUERY_H_