Transmitter.cpp

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/*
 * SNode.C - A Slim Toolkit for Network Communication
 * Copyright (C) Volker Christian <me@vchrist.at>
 *               2020, 2021, 2022, 2023, 2024, 2025
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
/*
 * MIT License
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
 
#include "web/websocket/Transmitter.h"
 
#ifndef DOXYGEN_SHOULD_SKIP_THIS
 
#include "log/Logger.h"
#include "utils/hexdump.h"
 
#include <endian.h>
#include <string>
#include <vector>
 
#endif /* DOXYGEN_SHOULD_SKIP_THIS */
 
#ifndef WSMAXFRAMEPAYLOADLENGTH
#define WSMAXFRAMEPAYLOADLENGTH 16384
#endif
 
namespace web::websocket {
 
    Transmitter::Transmitter(bool masking)
        : masking(masking) {
    }
 
    Transmitter::~Transmitter() {
    }
 
    void Transmitter::sendMessage(uint8_t opCode, const char* message, std::size_t messageLength) {
        send(true, opCode, message, messageLength);
    }
 
    void Transmitter::sendMessageStart(uint8_t opCode, const char* message, std::size_t messageLength) {
        send(false, opCode, message, messageLength);
    }
 
    void Transmitter::sendMessageFrame(const char* message, std::size_t messageLength) {
        send(false, 0, message, messageLength);
    }
 
    void Transmitter::sendMessageEnd(const char* message, std::size_t messageLength) {
        send(true, 0, message, messageLength);
    }
 
    std::size_t Transmitter::getPayloadTotalSent() const {
        return payloadTotalSent;
    }
 
    void Transmitter::send(bool end, uint8_t opCode, const char* message, std::size_t messageLength) {
        std::size_t messageOffset = 0;
 
        do {
            const std::size_t sendFrameLength =
                (messageLength - messageOffset <= WSMAXFRAMEPAYLOADLENGTH) ? messageLength - messageOffset : WSMAXFRAMEPAYLOADLENGTH;
 
            const bool fin = (sendFrameLength == messageLength - messageOffset) && end;
 
            sendFrame(fin, opCode, message + messageOffset, sendFrameLength);
 
            messageOffset += sendFrameLength;
 
            opCode = 0; // continuation
        } while (messageLength - messageOffset > 0);
 
        payloadTotalSent += messageLength;
    }
 
    void Transmitter::sendFrame(bool fin, uint8_t opCode, const char* payload, uint64_t payloadLength) {
        uint64_t length = 0;
 
        if (payloadLength < 126) {
            length = payloadLength;
        } else if (payloadLength < 0x10000) {
            length = 126;
        } else {
            length = 127;
        }
 
        char header[2];
        header[0] = static_cast<char>((fin ? 0b10000000 : 0) | opCode);
 
        header[1] = static_cast<char>((masking ? 0b10000000 : 0) | length);
 
        sendFrameData(header, 2);
 
        switch (length) {
            case 126:
                sendFrameData(static_cast<uint16_t>(payloadLength));
                break;
            case 127:
                sendFrameData(payloadLength);
                break;
        }
 
        union MaskingKey {
            uint32_t keyAsValue;
            char keyAsBytes[4];
        };
 
        MaskingKey maskingKeyAsArray = {.keyAsValue = distribution(randomDevice)};
 
        if (payloadLength > 0) {
            LOG(TRACE) << "WebSocket send: Frame data\n" << utils::hexDump(payload, payloadLength, 32, true);
        }
 
        if (masking) {
            sendFrameData(maskingKeyAsArray.keyAsBytes, 4);
 
            std::vector<char> maskedPayload(payload, payload + payloadLength);
            for (uint64_t i = 0; i < payloadLength; i++) {
                maskedPayload[static_cast<std::size_t>(i)] =
                    static_cast<char>(maskedPayload[static_cast<std::size_t>(i)] ^ maskingKeyAsArray.keyAsBytes[i % 4]);
            }
            sendFrameData(maskedPayload.data(), payloadLength);
        } else {
            sendFrameData(payload, payloadLength);
        }
    }
 
    void Transmitter::sendFrameData(uint8_t data) const {
        if (!closeSent) {
            sendFrameData(reinterpret_cast<char*>(&data), sizeof(uint8_t));
        }
    }
 
    void Transmitter::sendFrameData(uint16_t data) const {
        if (!closeSent) {
            uint16_t sendData = htobe16(data);
            sendFrameData(reinterpret_cast<char*>(&sendData), sizeof(uint16_t));
        }
    }
 
    void Transmitter::sendFrameData(uint32_t data) const {
        if (!closeSent) {
            uint32_t sendData = htobe32(data);
            sendFrameData(reinterpret_cast<char*>(&sendData), sizeof(uint32_t));
        }
    }
 
    void Transmitter::sendFrameData(uint64_t data) const {
        if (!closeSent) {
            uint64_t sendData = htobe64(data);
            sendFrameData(reinterpret_cast<char*>(&sendData), sizeof(uint64_t));
        }
    }
 
    void Transmitter::sendFrameData(const char* frame, uint64_t frameLength) const {
        if (!closeSent) {
            uint64_t frameOffset = 0;
 
            do {
                const std::size_t sendChunkLen =
                    (frameLength - frameOffset <= SIZE_MAX) ? static_cast<std::size_t>(frameLength - frameOffset) : SIZE_MAX;
 
                sendFrameChunk(frame + frameOffset, sendChunkLen);
 
                frameOffset += sendChunkLen;
            } while (frameLength - frameOffset > 0);
        }
    }
 
} // namespace web::websocket