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// Copyright 2019 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 CAST_COMMON_MDNS_MDNS_WRITER_H_
#define CAST_COMMON_MDNS_MDNS_WRITER_H_
#include <unordered_map>
#include "absl/strings/string_view.h"
#include "cast/common/mdns/mdns_records.h"
#include "util/big_endian.h"
namespace cast {
namespace mdns {
class MdnsWriter : public openscreen::BigEndianWriter {
public:
using BigEndianWriter::BigEndianWriter;
using BigEndianWriter::Write;
// The following methods return true if the method was able to successfully
// write the value to the underlying buffer and advances current() to point
// right past the written data. Returns false if the method failed to write
// the value to the underlying buffer, current() remains unchanged.
bool Write(absl::string_view value);
bool Write(const std::string& value);
bool Write(const DomainName& name);
bool Write(const RawRecordRdata& rdata);
bool Write(const SrvRecordRdata& rdata);
bool Write(const ARecordRdata& rdata);
bool Write(const AAAARecordRdata& rdata);
bool Write(const PtrRecordRdata& rdata);
bool Write(const TxtRecordRdata& rdata);
// Writes a DNS resource record with its RDATA.
// The correct type of RDATA to be written is contained in the type
// specified in the record.
bool Write(const MdnsRecord& record);
bool Write(const MdnsQuestion& question);
// Writes multiple mDNS questions and records that are a part of
// a mDNS message being read
bool Write(const MdnsMessage& message);
private:
bool Write(const IPAddress& address);
bool Write(const Rdata& rdata);
bool Write(const Header& header);
template <class ItemType>
bool Write(const std::vector<ItemType>& collection) {
Cursor cursor(this);
for (const ItemType& entry : collection) {
if (!Write(entry)) {
return false;
}
}
cursor.Commit();
return true;
}
// Domain name compression dictionary.
// Maps hashes of previously written domain (sub)names
// to the label pointers of the first occurences in the underlying buffer.
// Compression of multiple domain names is supported on the same instance of
// the MdnsWriter. Underlying buffer may contain other data in addition to the
// domain names. The compression dictionary persists between calls to
// Write.
// Label pointer is only 16 bits in size as per RFC 1035. Only lower 14 bits
// are allocated for storing the offset.
std::unordered_map<uint64_t, uint16_t> dictionary_;
};
} // namespace mdns
} // namespace cast
#endif // CAST_COMMON_MDNS_MDNS_WRITER_H_
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