1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
|
// 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_CLIENT_H_
#define NET_DNS_DNS_CLIENT_H_
#pragma once
#include <string>
#include "base/basictypes.h"
#include "base/callback.h"
#include "base/memory/weak_ptr.h"
#include "net/base/net_export.h"
namespace base {
class StringPiece;
}
namespace net {
class BoundNetLog;
class ClientSocketFactory;
class DnsResponse;
class DnsSession;
// DnsClient performs asynchronous DNS queries. DnsClient takes care of
// retransmissions, DNS server fallback (or round-robin), suffix search, and
// simple response validation ("does it match the query") to fight poisoning.
// It does NOT perform caching, aggregation or prioritization of requests.
//
// Destroying DnsClient does NOT affect any already created Requests.
//
// TODO(szym): consider adding flags to MakeRequest to indicate options:
// -- don't perform suffix search
// -- query both A and AAAA at once
// -- accept truncated response (and/or forbid TCP)
class NET_EXPORT_PRIVATE DnsClient {
public:
class Request;
// Callback for complete requests. Note that DnsResponse might be NULL if
// the DNS server(s) could not be reached.
typedef base::Callback<void(Request* req,
int result,
const DnsResponse* resp)> RequestCallback;
// A data-holder for a request made to the DnsClient.
// Destroying the request cancels the underlying network effort.
class NET_EXPORT_PRIVATE Request {
public:
Request(const base::StringPiece& qname,
uint16 qtype,
const RequestCallback& callback);
virtual ~Request();
const std::string& qname() const { return qname_; }
uint16 qtype() const { return qtype_; }
virtual int Start() = 0;
void DoCallback(int result, const DnsResponse* response) {
callback_.Run(this, result, response);
}
private:
std::string qname_;
uint16 qtype_;
RequestCallback callback_;
DISALLOW_COPY_AND_ASSIGN(Request);
};
virtual ~DnsClient() {}
// Makes asynchronous DNS query for the given |qname| and |qtype| (assuming
// QCLASS == IN). The caller is responsible for destroying the returned
// request whether to cancel it or after its completion.
// (Destroying DnsClient does not abort the requests.)
virtual Request* CreateRequest(
const base::StringPiece& qname,
uint16 qtype,
const RequestCallback& callback,
const BoundNetLog& source_net_log) WARN_UNUSED_RESULT = 0;
// Creates a socket-based DnsClient using the |session|.
static DnsClient* CreateClient(DnsSession* session) WARN_UNUSED_RESULT;
};
} // namespace net
#endif // NET_DNS_DNS_CLIENT_H_
|
