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crossdesk/src/tools/file_transfer.h

122 lines
3.7 KiB
C++

/*
* @Author: DI JUNKUN
* @Date: 2025-12-18
* Copyright (c) 2025 by DI JUNKUN, All Rights Reserved.
*/
#ifndef _FILE_TRANSFER_H_
#define _FILE_TRANSFER_H_
#include <cstdint>
#include <filesystem>
#include <fstream>
#include <functional>
#include <string>
#include <unordered_map>
#include <vector>
namespace crossdesk {
// Magic constants for file transfer protocol
constexpr uint32_t kFileChunkMagic = 0x4A4E544D; // 'JNTM'
constexpr uint32_t kFileAckMagic = 0x4A4E5443; // 'JNTC'
#pragma pack(push, 1)
struct FileChunkHeader {
uint32_t magic; // magic to identify file-transfer chunks
uint32_t file_id; // unique id per file transfer
uint64_t offset; // offset in file
uint64_t total_size; // total file size
uint32_t chunk_size; // payload size in this chunk
uint16_t name_len; // filename length (bytes), only set on first chunk
uint8_t flags; // bit0: is_first, bit1: is_last, others reserved
};
struct FileTransferAck {
uint32_t magic; // magic to identify file-transfer ack
uint32_t file_id; // must match FileChunkHeader.file_id
uint64_t acked_offset; // received offset
uint64_t total_size; // total file size
uint32_t flags; // bit0: completed, bit1: error
};
#pragma pack(pop)
class FileSender {
public:
using SendFunc = std::function<int(const char* data, size_t size)>;
public:
FileSender() = default;
// generate a new file id
static uint32_t NextFileId();
// synchronously send a file using the provided send function.
// `path` : full path to the local file.
// `label` : logical filename to send (usually path.filename()).
// `send` : callback that pushes one encoded chunk into the data channel.
// `file_id` : file id to use (0 means auto-generate).
// Return 0 on success, <0 on error.
int SendFile(const std::filesystem::path& path, const std::string& label,
const SendFunc& send, std::size_t chunk_size = 64 * 1024,
uint32_t file_id = 0);
// build a single encoded chunk buffer according to FileChunkHeader protocol.
static std::vector<char> BuildChunk(uint32_t file_id, uint64_t offset,
uint64_t total_size, const char* data,
uint32_t data_size,
const std::string* file_name,
bool is_first, bool is_last);
};
class FileReceiver {
public:
struct FileContext {
std::string file_name;
uint64_t total_size = 0;
uint64_t received = 0;
std::ofstream ofs;
};
using OnFileComplete =
std::function<void(const std::filesystem::path& saved_path)>;
using OnSendAck = std::function<int(const FileTransferAck& ack)>;
public:
// save to default desktop directory.
FileReceiver();
// save to a specified directory.
explicit FileReceiver(const std::filesystem::path& output_dir);
// process one received data buffer (one chunk).
// return true if parsed and processed successfully, false otherwise.
bool OnData(const char* data, size_t size);
void SetOnSendAck(OnSendAck cb) { on_send_ack_ = cb; }
const std::filesystem::path& OutputDir() const { return output_dir_; }
void SetOutputDir(const std::filesystem::path& dir) {
output_dir_ = dir;
if (!output_dir_.empty()) {
std::error_code ec;
std::filesystem::create_directories(output_dir_, ec);
}
}
private:
static std::filesystem::path GetDefaultDesktopPath();
bool HandleChunk(const FileChunkHeader& header, const char* payload,
size_t payload_size, const std::string* file_name);
private:
std::filesystem::path output_dir_;
std::unordered_map<uint32_t, FileContext> contexts_;
OnSendAck on_send_ack_ = nullptr;
};
} // namespace crossdesk
#endif