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