77 lines
2.6 KiB
C++
77 lines
2.6 KiB
C++
// SPDX-FileCopyrightText: 2018 Citra Emulator Project
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// SPDX-License-Identifier: GPL-2.0-or-later
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#include <cstddef>
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#include <cstring>
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#include "common/logging/log.h"
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#include "input_common/helpers/udp_protocol.h"
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namespace InputCommon::CemuhookUDP {
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static constexpr std::size_t GetSizeOfResponseType(Type t) {
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switch (t) {
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case Type::Version:
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return sizeof(Response::Version);
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case Type::PortInfo:
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return sizeof(Response::PortInfo);
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case Type::PadData:
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return sizeof(Response::PadData);
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}
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return 0;
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}
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namespace Response {
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/**
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* Returns Type if the packet is valid, else none
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*
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* Note: Modifies the buffer to zero out the crc (since that's the easiest way to check without
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* copying the buffer)
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*/
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std::optional<Type> Validate(u8* data, std::size_t size) {
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if (size < sizeof(Header)) {
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return std::nullopt;
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}
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Header header{};
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std::memcpy(&header, data, sizeof(Header));
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if (header.magic != SERVER_MAGIC) {
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LOG_ERROR(Input, "UDP Packet has an unexpected magic value");
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return std::nullopt;
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}
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if (header.protocol_version != PROTOCOL_VERSION) {
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LOG_ERROR(Input, "UDP Packet protocol mismatch");
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return std::nullopt;
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}
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if (header.type < Type::Version || header.type > Type::PadData) {
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LOG_ERROR(Input, "UDP Packet is an unknown type");
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return std::nullopt;
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}
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// Packet size must equal sizeof(Header) + sizeof(Data)
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// and also verify that the packet info mentions the correct size. Since the spec includes the
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// type of the packet as part of the data, we need to include it in size calculations here
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// ie: payload_length == sizeof(T) + sizeof(Type)
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const std::size_t data_len = GetSizeOfResponseType(header.type);
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if (header.payload_length != data_len + sizeof(Type) || size < data_len + sizeof(Header)) {
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LOG_ERROR(
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Input,
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"UDP Packet payload length doesn't match. Received: {} PayloadLength: {} Expected: {}",
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size, header.payload_length, data_len + sizeof(Type));
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return std::nullopt;
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}
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const u32 crc32 = header.crc;
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boost::crc_32_type result;
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// zero out the crc in the buffer and then run the crc against it
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std::memset(&data[offsetof(Header, crc)], 0, sizeof(u32_le));
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result.process_bytes(data, data_len + sizeof(Header));
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if (crc32 != result.checksum()) {
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LOG_ERROR(Input, "UDP Packet CRC check failed. Offset: {}", offsetof(Header, crc));
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return std::nullopt;
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}
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return header.type;
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}
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} // namespace Response
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} // namespace InputCommon::CemuhookUDP
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