Receiver.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,
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 * THE SOFTWARE.
 */
 
#include "web/websocket/Receiver.h"
 
#ifndef DOXYGEN_SHOULD_SKIP_THIS
 
#include "log/Logger.h"
#include "utils/hexdump.h"
 
#include <endian.h>
#include <string>
 
#endif /* DOXYGEN_SHOULD_SKIP_THIS */
 
#ifndef MAX_PAYLOAD_CHUNK_LEN
#define MAX_PAYLOAD_CHUNK_LEN 16384
#endif
 
namespace web::websocket {
 
    Receiver::Receiver(bool maskingExpected)
        : maskingExpected(maskingExpected) {
    }
 
    Receiver::~Receiver() {
    }
 
    std::size_t Receiver::receive() {
        std::size_t ret = 0;
        std::size_t consumed = 0;
 
        // dumpFrame(chunk, chunkLen);
 
        do {
            switch (parserState) {
                case ParserState::BEGIN:
                    parserState = ParserState::OPCODE;
                    [[fallthrough]];
                case ParserState::OPCODE:
                    ret = readOpcode();
                    break;
                case ParserState::LENGTH:
                    ret = readLength();
                    break;
                case ParserState::ELENGTH:
                    ret = readELength();
                    break;
                case ParserState::MASKINGKEY:
                    ret = readMaskingKey();
                    break;
                case ParserState::PAYLOAD:
                    ret = readPayload();
                    break;
                case ParserState::ERROR:
                    onMessageError(errorState);
                    reset();
                    break;
            }
            consumed += ret;
        } while (ret > 0 && parserState != ParserState::BEGIN && parserState != ParserState::ERROR);
 
        return consumed;
    }
 
    std::size_t Receiver::getPayloadTotalRead() const {
        return payloadTotalRead;
    }
 
    std::size_t Receiver::readFrameData(char* chunk, std::size_t chunkLen) {
        return readFrameChunk(chunk, chunkLen);
    }
 
    std::size_t Receiver::readOpcode() {
        char byte = 0;
        const std::size_t ret = readFrameData(&byte, 1);
 
        if (ret > 0) {
            const uint8_t opCodeByte = static_cast<uint8_t>(byte);
 
            fin = (opCodeByte & 0b10000000) != 0;
            opCode = opCodeByte & 0b00001111;
 
            if (!continuation) {
                onMessageStart(opCode);
                parserState = ParserState::LENGTH;
            } else if (opCode == 0) {
                parserState = ParserState::LENGTH;
            } else {
                parserState = ParserState::ERROR;
                errorState = 1002;
                LOG(ERROR) << "WebSocket: Error opcode in continuation frame";
            }
            continuation = !fin;
        }
 
        return ret;
    }
 
    std::size_t Receiver::readLength() {
        char byte = 0;
        const std::size_t ret = readFrameData(&byte, 1);
 
        if (ret > 0) {
            const uint8_t lengthByte = static_cast<uint8_t>(byte);
 
            masked = (lengthByte & 0b10000000) != 0;
            if (masked == maskingExpected) {
                payloadNumBytes = payloadNumBytesLeft = lengthByte & 0b01111111;
 
                if (payloadNumBytes > 125) {
                    switch (payloadNumBytes) {
                        case 126:
                            elengthNumBytes = elengthNumBytesLeft = 2;
                            break;
                        case 127:
                            elengthNumBytes = elengthNumBytesLeft = 8;
                            break;
                    }
                    parserState = ParserState::ELENGTH;
                    payloadNumBytes = payloadNumBytesLeft = 0;
                } else {
                    if (masked) {
                        parserState = ParserState::MASKINGKEY;
                    } else if (payloadNumBytes > 0) {
                        parserState = ParserState::PAYLOAD;
                    } else {
                        if (fin) {
                            onMessageEnd();
                        }
                        reset();
                    }
                }
            } else {
                parserState = ParserState::ERROR;
            }
        }
 
        return ret;
    }
 
    std::size_t Receiver::readELength2() {
        char elengthChunk[2]{};
 
        const std::size_t ret = readFrameData(elengthChunk, elengthNumBytesLeft);
 
        const std::size_t cursor = static_cast<std::size_t>(elengthNumBytes - elengthNumBytesLeft);
        for (std::size_t i = 0; i < ret; i++) {
            eLength2.asBytes[cursor + i] = elengthChunk[i];
            elengthNumBytesLeft--;
        }
 
        if (elengthNumBytesLeft == 0) {
            payloadNumBytes = payloadNumBytesLeft = be16toh(eLength2.asValue);
        }
 
        return ret;
    }
 
    std::size_t Receiver::readELength8() {
        char elengthChunk[8]{};
 
        const std::size_t ret = readFrameData(elengthChunk, elengthNumBytesLeft);
 
        const std::size_t cursor = static_cast<std::size_t>(elengthNumBytes - elengthNumBytesLeft);
        for (std::size_t i = 0; i < ret; i++) {
            eLength8.asBytes[cursor + i] = elengthChunk[i];
            elengthNumBytesLeft--;
        }
 
        if (elengthNumBytesLeft == 0) {
            payloadNumBytes = payloadNumBytesLeft = be64toh(eLength8.asValue);
        }
 
        return ret;
    }
 
    std::size_t Receiver::readELength() {
        std::size_t ret = 0;
 
        switch (elengthNumBytes) {
            case 2:
                ret = readELength2();
                break;
            case 8:
                ret = readELength8();
                break;
        }
 
        if (elengthNumBytesLeft == 0) {
            if ((payloadNumBytes & static_cast<uint64_t>(0x01) << 63) != 0) {
                parserState = ParserState::ERROR;
                errorState = 1004;
            } else if (masked) {
                parserState = ParserState::MASKINGKEY;
            } else {
                parserState = ParserState::PAYLOAD;
            }
        }
 
        return ret;
    }
 
    std::size_t Receiver::readMaskingKey() {
        char maskingKeyChunk[4]{};
 
        const std::size_t ret = readFrameData(maskingKeyChunk, maskingKeyNumBytesLeft);
 
        const std::size_t cursor = static_cast<std::size_t>(maskingKeyNumBytes - maskingKeyNumBytesLeft);
        for (std::size_t i = 0; i < ret; i++) {
            maskingKey[cursor + i] = maskingKeyChunk[i];
            maskingKeyNumBytesLeft -= 1;
        }
 
        if (maskingKeyNumBytesLeft == 0) {
            if (payloadNumBytes > 0) {
                parserState = ParserState::PAYLOAD;
            } else {
                if (fin) {
                    onMessageEnd();
                }
                reset();
            }
        }
 
        return ret;
    }
 
    std::size_t Receiver::readPayload() {
        char payloadChunk[MAX_PAYLOAD_CHUNK_LEN]{};
 
        const std::size_t payloadChunkLeft = (MAX_PAYLOAD_CHUNK_LEN <= payloadNumBytesLeft)
                                                 ? static_cast<std::size_t>(MAX_PAYLOAD_CHUNK_LEN)
                                                 : static_cast<std::size_t>(payloadNumBytesLeft);
        const std::size_t ret = readFrameData(payloadChunk, payloadChunkLeft);
 
        if (ret > 0) {
            const std::size_t payloadChunkLen = static_cast<std::size_t>(ret);
 
            if (masked) {
                for (std::size_t i = 0; i < payloadChunkLen; i++) {
                    *(payloadChunk + i) = *(payloadChunk + i) ^ *(maskingKey + (i + payloadNumBytes - payloadNumBytesLeft) % 4);
                }
            }
 
            LOG(TRACE) << "WebSocket receive: Frame data\n" << utils::hexDump(payloadChunk, payloadChunkLen, 32, true);
 
            onMessageData(payloadChunk, payloadChunkLen);
 
            payloadNumBytesLeft -= payloadChunkLen;
            payloadTotalRead += payloadChunkLen;
        }
 
        if (payloadNumBytesLeft == 0) {
            if (fin) {
                onMessageEnd();
            }
            reset();
        }
 
        return ret;
    }
 
    void Receiver::reset() {
        parserState = ParserState::BEGIN;
 
        fin = false;
        continuation = false;
        masked = false;
 
        opCode = 0;
 
        elengthNumBytes = 0;
        elengthNumBytesLeft = 0;
 
        payloadNumBytes = 0;
        payloadNumBytesLeft = 0;
 
        maskingKeyNumBytes = 4;
        maskingKeyNumBytesLeft = 4;
 
        errorState = 0;
    }
 
} // namespace web::websocket