// 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 #include #include #include #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 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 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 io_buffer_; // Pointer to the dns header section. dns_protocol::Header* header_ = nullptr; }; } // namespace net #endif // NET_DNS_DNS_QUERY_H_