src/lib/dnssd/wire/Query.h

/*
 *
 *    Copyright (c) 2020 Project CHIP Authors
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

#pragma once

#include <lib/support/BufferWriter.h>

#include <lib/dnssd/wire/Constants.h>
#include <lib/dnssd/wire/QName.h>
#include <lib/dnssd/wire/RecordWriter.h>

namespace chip {
namespace Dnssd {

/// Represents a MDNS Query: QName and flags
class Query
{
public:
    Query(FullQName name) : mQName(name) {}

    bool IsAnswerViaUnicast() const { return mAnswerViaUnicast; }
    Query & SetAnswerViaUnicast(bool value)
    {
        mAnswerViaUnicast = value;
        return *this;
    }

    QType GetType() const { return mType; }
    Query & SetType(QType value)
    {
        mType = value;
        return *this;
    }

    QClass GetClass() const { return mClass; }
    Query & SetClass(QClass value)
    {
        mClass = value;
        return *this;
    }

    const FullQName & GetName() const { return mQName; }

    /// Append the query to the specified buffer
    ///
    /// @param hdr will be updated with a query count
    /// @param out where to write the query data
    bool Append(HeaderRef & hdr, RecordWriter & out) const
    {
        // Questions can only be appended before any other data is added
        if ((hdr.GetAdditionalCount() != 0) || (hdr.GetAnswerCount() != 0) || (hdr.GetAuthorityCount() != 0))
        {
            return false;
        }

        out.WriteQName(mQName)
            .Put16(static_cast<uint16_t>(mType))
            .Put16(static_cast<uint16_t>(static_cast<uint16_t>(mClass) | (mAnswerViaUnicast ? kQClassUnicastAnswerFlag : 0)));

        if (!out.Fit())
        {
            return false;
        }

        hdr.SetQueryCount(static_cast<uint16_t>(hdr.GetQueryCount() + 1));
        return true;
    }

private:
    const FullQName mQName;
    QType mType            = QType::ANY;
    QClass mClass          = QClass::IN;
    bool mAnswerViaUnicast = true;
};

} // namespace Dnssd

} // namespace chip