mavlink_ftp.h

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#pragma once


#include <dirent.h>
#include <queue.h>

#include <px4_defines.h>
#include <systemlib/err.h>
#include <drivers/drv_hrt.h>

#include "mavlink_bridge_header.h"

class MavlinkFtpTest;
class Mavlink;

class MavlinkFTP
{
public:
    MavlinkFTP(Mavlink *mavlink);
    ~MavlinkFTP();

    void send(const hrt_abstime t);

    void handle_message(const mavlink_message_t *msg);

    typedef void (*ReceiveMessageFunc_t)(const mavlink_file_transfer_protocol_t *ftp_req, void *worker_data);

    void set_unittest_worker(ReceiveMessageFunc_t rcvMsgFunc, void *worker_data);

    struct __attribute__((__packed__)) PayloadHeader {
        uint16_t    seq_number; 
        uint8_t     session;    
        uint8_t     opcode;     
        uint8_t     size;       
        uint8_t     req_opcode; 
        uint8_t     burst_complete; 
        uint8_t     padding;        
        uint32_t    offset;     
        uint8_t     data[];     
    };

    enum Opcode : uint8_t {
        kCmdNone,       
        kCmdTerminateSession,   
        kCmdResetSessions,  
        kCmdListDirectory,  
        kCmdOpenFileRO,     
        kCmdReadFile,       
        kCmdCreateFile,     
        kCmdWriteFile,      
        kCmdRemoveFile,     
        kCmdCreateDirectory,    
        kCmdRemoveDirectory,    
        kCmdOpenFileWO,     
        kCmdTruncateFile,   
        kCmdRename,     
        kCmdCalcFileCRC32,  
        kCmdBurstReadFile,  

        kRspAck = 128,      
        kRspNak         
    };

    enum ErrorCode : uint8_t {
        kErrNone,
        kErrFail,           
        kErrFailErrno,          
        kErrInvalidDataSize,        
        kErrInvalidSession,     
        kErrNoSessionsAvailable,    
        kErrEOF,            
        kErrUnknownCommand,     
        kErrFailFileExists,     
        kErrFailFileProtected       
    };

    unsigned get_size();

private:
    char        *_data_as_cstring(PayloadHeader *payload);

    void        _process_request(mavlink_file_transfer_protocol_t *ftp_req, uint8_t target_system_id);
    void        _reply(mavlink_file_transfer_protocol_t *ftp_req);
    int     _copy_file(const char *src_path, const char *dst_path, size_t length);

    ErrorCode   _workList(PayloadHeader *payload, bool list_hidden = false);
    ErrorCode   _workOpen(PayloadHeader *payload, int oflag);
    ErrorCode   _workRead(PayloadHeader *payload);
    ErrorCode   _workBurst(PayloadHeader *payload, uint8_t target_system_id);
    ErrorCode   _workWrite(PayloadHeader *payload);
    ErrorCode   _workTerminate(PayloadHeader *payload);
    ErrorCode   _workReset(PayloadHeader *payload);
    ErrorCode   _workRemoveDirectory(PayloadHeader *payload);
    ErrorCode   _workCreateDirectory(PayloadHeader *payload);
    ErrorCode   _workRemoveFile(PayloadHeader *payload);
    ErrorCode   _workTruncateFile(PayloadHeader *payload);
    ErrorCode   _workRename(PayloadHeader *payload);
    ErrorCode   _workCalcFileCRC32(PayloadHeader *payload);

    uint8_t _getServerSystemId(void);
    uint8_t _getServerComponentId(void);
    uint8_t _getServerChannel(void);

    bool _ensure_buffers_exist();

    static const char   kDirentFile = 'F';  
    static const char   kDirentDir = 'D';   
    static const char   kDirentSkip = 'S';  

    static const uint8_t    kMaxDataLength = MAVLINK_MSG_FILE_TRANSFER_PROTOCOL_FIELD_PAYLOAD_LEN - sizeof(PayloadHeader);

    struct SessionInfo {
        int     fd;
        uint32_t    file_size;
        bool        stream_download;
        uint32_t    stream_offset;
        uint16_t    stream_seq_number;
        uint8_t     stream_target_system_id;
        unsigned    stream_chunk_transmitted;
    };
    struct SessionInfo _session_info {};    

    ReceiveMessageFunc_t    _utRcvMsgFunc{};    
    void            *_worker_data{nullptr}; 

    Mavlink *_mavlink;

    /* do not allow copying this class */
    MavlinkFTP(const MavlinkFTP &);
    MavlinkFTP operator=(const MavlinkFTP &);

    /* work buffers: they're allocated as soon as we get the first request (lazy, since FTP is rarely used) */
    char *_work_buffer1{nullptr};
    static constexpr int _work_buffer1_len = kMaxDataLength;
    char *_work_buffer2{nullptr};
    static constexpr int _work_buffer2_len = 256;
    hrt_abstime _last_work_buffer_access{0}; 

    // prepend a root directory to each file/dir access to avoid enumerating the full FS tree (e.g. on Linux).
    // Note that requests can still fall outside of the root dir by using ../..
#ifdef MAVLINK_FTP_UNIT_TEST
    static constexpr const char _root_dir[] = "";
#else
    static constexpr const char _root_dir[] = PX4_ROOTFSDIR;
#endif
    static constexpr const int _root_dir_len = sizeof(_root_dir) - 1;

    bool _last_reply_valid = false;
    uint8_t _last_reply[MAVLINK_MSG_ID_FILE_TRANSFER_PROTOCOL_LEN - MAVLINK_MSG_FILE_TRANSFER_PROTOCOL_FIELD_PAYLOAD_LEN
                                      + sizeof(PayloadHeader) + sizeof(uint32_t)];

    // Mavlink test needs to be able to call send
    friend class MavlinkFtpTest;
};