1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "net/dns/dns_query.h"
6
7 #include <limits>
8
9 #include "base/sys_byteorder.h"
10 #include "net/base/big_endian.h"
11 #include "net/base/dns_util.h"
12 #include "net/base/io_buffer.h"
13 #include "net/dns/dns_protocol.h"
14
15 namespace net {
16
17 // DNS query consists of a 12-byte header followed by a question section.
18 // For details, see RFC 1035 section 4.1.1. This header template sets RD
19 // bit, which directs the name server to pursue query recursively, and sets
20 // the QDCOUNT to 1, meaning the question section has a single entry.
DnsQuery(uint16 id,const base::StringPiece & qname,uint16 qtype)21 DnsQuery::DnsQuery(uint16 id, const base::StringPiece& qname, uint16 qtype)
22 : qname_size_(qname.size()) {
23 DCHECK(!DNSDomainToString(qname).empty());
24 // QNAME + QTYPE + QCLASS
25 size_t question_size = qname_size_ + sizeof(uint16) + sizeof(uint16);
26 io_buffer_ = new IOBufferWithSize(sizeof(dns_protocol::Header) +
27 question_size);
28 dns_protocol::Header* header =
29 reinterpret_cast<dns_protocol::Header*>(io_buffer_->data());
30 memset(header, 0, sizeof(dns_protocol::Header));
31 header->id = base::HostToNet16(id);
32 header->flags = base::HostToNet16(dns_protocol::kFlagRD);
33 header->qdcount = base::HostToNet16(1);
34
35 // Write question section after the header.
36 BigEndianWriter writer(reinterpret_cast<char*>(header + 1), question_size);
37 writer.WriteBytes(qname.data(), qname.size());
38 writer.WriteU16(qtype);
39 writer.WriteU16(dns_protocol::kClassIN);
40 }
41
~DnsQuery()42 DnsQuery::~DnsQuery() {
43 }
44
CloneWithNewId(uint16 id) const45 DnsQuery* DnsQuery::CloneWithNewId(uint16 id) const {
46 return new DnsQuery(*this, id);
47 }
48
id() const49 uint16 DnsQuery::id() const {
50 const dns_protocol::Header* header =
51 reinterpret_cast<const dns_protocol::Header*>(io_buffer_->data());
52 return base::NetToHost16(header->id);
53 }
54
qname() const55 base::StringPiece DnsQuery::qname() const {
56 return base::StringPiece(io_buffer_->data() + sizeof(dns_protocol::Header),
57 qname_size_);
58 }
59
qtype() const60 uint16 DnsQuery::qtype() const {
61 uint16 type;
62 ReadBigEndian<uint16>(io_buffer_->data() +
63 sizeof(dns_protocol::Header) +
64 qname_size_, &type);
65 return type;
66 }
67
question() const68 base::StringPiece DnsQuery::question() const {
69 return base::StringPiece(io_buffer_->data() + sizeof(dns_protocol::Header),
70 qname_size_ + sizeof(uint16) + sizeof(uint16));
71 }
72
DnsQuery(const DnsQuery & orig,uint16 id)73 DnsQuery::DnsQuery(const DnsQuery& orig, uint16 id) {
74 qname_size_ = orig.qname_size_;
75 io_buffer_ = new IOBufferWithSize(orig.io_buffer()->size());
76 memcpy(io_buffer_.get()->data(), orig.io_buffer()->data(),
77 io_buffer_.get()->size());
78 dns_protocol::Header* header =
79 reinterpret_cast<dns_protocol::Header*>(io_buffer_->data());
80 header->id = base::HostToNet16(id);
81 }
82
set_flags(uint16 flags)83 void DnsQuery::set_flags(uint16 flags) {
84 dns_protocol::Header* header =
85 reinterpret_cast<dns_protocol::Header*>(io_buffer_->data());
86 header->flags = flags;
87 }
88
89 } // namespace net
90