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124 lines
4.1 KiB
C++
124 lines
4.1 KiB
C++
// Copyright 2011 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef NET_DNS_DNS_QUERY_H_
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#define NET_DNS_DNS_QUERY_H_
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#include <stddef.h>
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#include <stdint.h>
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#include <memory>
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#include <string>
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#include "base/containers/span.h"
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#include "base/memory/raw_ptr.h"
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#include "base/memory/scoped_refptr.h"
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#include "base/strings/string_piece.h"
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#include "net/base/net_export.h"
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namespace base {
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class BigEndianReader;
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} // namespace base
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namespace net {
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class OptRecordRdata;
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namespace dns_protocol {
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struct Header;
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} // namespace dns_protocol
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class IOBufferWithSize;
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// Represents on-the-wire DNS query message as an object.
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class NET_EXPORT_PRIVATE DnsQuery {
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public:
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enum class PaddingStrategy {
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// Query will not be padded. Recommended strategy when query will not be
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// encrypted.
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NONE,
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// Query will be padded to the next multiple of 128 octets. Recommended
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// strategy (per RFC 8467) when query will be encrypted, e.g. through
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// DNS-over-HTTPS.
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BLOCK_LENGTH_128,
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};
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// Constructs a query message from |qname| which *MUST* be in a valid
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// DNS name format, and |qtype|. The qclass is set to IN.
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// If |opt_rdata| is not null, an OPT record will be added to the "Additional"
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// section of the query.
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DnsQuery(uint16_t id,
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base::span<const uint8_t> qname,
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uint16_t qtype,
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const OptRecordRdata* opt_rdata = nullptr,
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PaddingStrategy padding_strategy = PaddingStrategy::NONE);
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// Constructs an empty query from a raw packet in |buffer|. If the raw packet
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// represents a valid DNS query in the wire format (RFC 1035), Parse() will
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// populate the empty query.
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explicit DnsQuery(scoped_refptr<IOBufferWithSize> buffer);
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// Copies are constructed with an independent cloned, not mirrored, buffer.
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DnsQuery(const DnsQuery& query);
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DnsQuery& operator=(const DnsQuery& query);
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~DnsQuery();
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// Clones |this| verbatim, with ID field of the header set to |id|.
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std::unique_ptr<DnsQuery> CloneWithNewId(uint16_t id) const;
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// Returns true and populates the query if the internally stored raw packet
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// can be parsed. This should only be called when DnsQuery is constructed from
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// the raw buffer.
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// |valid_bytes| indicates the number of initialized bytes in the raw buffer.
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// E.g. if the buffer holds a packet received from the network, the buffer may
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// be allocated with the maximum size of a UDP packet, but |valid_bytes|
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// indicates the number of bytes actually received from the network. If the
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// parsing requires reading more than the number of initialized bytes, this
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// method fails and returns false.
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bool Parse(size_t valid_bytes);
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// DnsQuery field accessors.
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uint16_t id() const;
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base::span<const uint8_t> qname() const;
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uint16_t qtype() const;
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// Returns the Question section of the query. Used when matching the
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// response.
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base::StringPiece question() const;
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// Returns the size of the question section.
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size_t question_size() const;
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// IOBuffer accessor to be used for writing out the query. The buffer has
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// the same byte layout as the DNS query wire format.
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IOBufferWithSize* io_buffer() const { return io_buffer_.get(); }
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void set_flags(uint16_t flags);
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private:
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DnsQuery(const DnsQuery& orig, uint16_t id);
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void CopyFrom(const DnsQuery& orig);
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bool ReadHeader(base::BigEndianReader* reader, dns_protocol::Header* out);
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// After read, |out| is in the DNS format, e.g.
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// "\x03""www""\x08""chromium""\x03""com""\x00". Use DNSDomainToString to
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// convert to the dotted format "www.chromium.com" with no trailing dot.
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bool ReadName(base::BigEndianReader* reader, std::string* out);
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// Size of the DNS name (*NOT* hostname) we are trying to resolve; used
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// to calculate offsets.
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size_t qname_size_ = 0;
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// Contains query bytes to be consumed by higher level Write() call.
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scoped_refptr<IOBufferWithSize> io_buffer_;
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// Pointer to the dns header section.
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raw_ptr<dns_protocol::Header> header_ = nullptr;
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};
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} // namespace net
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#endif // NET_DNS_DNS_QUERY_H_
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