mavlink_ftp.h

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#pragma once

/// @file mavlink_ftp.h
///     @author px4dev, Don Gagne <don@thegagnes.com>

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

#include <px4_platform_common/defines.h>
#include <systemlib/err.h>
#include <drivers/drv_hrt.h>

#include "mavlink_bridge_header.h"

class MavlinkFtpTest;
class Mavlink;

/// MAVLink remote file server. Support FTP like commands using MAVLINK_MSG_ID_FILE_TRANSFER_PROTOCOL message.
class MavlinkFTP
{
public:
    MavlinkFTP(Mavlink *mavlink);
    ~MavlinkFTP();

    /**
     * Handle sending of messages. Call this regularly at a fixed frequency.
     * @param t current time
     */
    void send(const hrt_abstime t);

    /// Handle possible FTP message
    void handle_message(const mavlink_message_t *msg);

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

    /// @brief Sets up the server to run in unit test mode.
    /// @param rcvmsgFunc Function which will be called to handle outgoing mavlink messages.
    /// @param worker_data Data to pass to worker
    void set_unittest_worker(ReceiveMessageFunc_t rcvMsgFunc, void *worker_data);

    /// @brief This is the payload which is in mavlink_file_transfer_protocol_t.payload.
    /// This needs to be packed, because it's typecasted from mavlink_file_transfer_protocol_t.payload, which starts
    /// at a 3 byte offset, causing an unaligned access to seq_number and offset
    struct __attribute__((__packed__)) PayloadHeader {
        uint16_t    seq_number; ///< sequence number for message
        uint8_t     session;    ///< Session id for read and write commands
        uint8_t     opcode;     ///< Command opcode
        uint8_t     size;       ///< Size of data
        uint8_t     req_opcode; ///< Request opcode returned in kRspAck, kRspNak message
        uint8_t     burst_complete; ///< Only used if req_opcode=kCmdBurstReadFile - 1: set of burst packets complete, 0: More burst packets coming.
        uint8_t     padding;        ///< 32 bit aligment padding
        uint32_t    offset;     ///< Offsets for List and Read commands
        uint8_t     data[];     ///< command data, varies by Opcode
    };

    /// @brief Command opcodes
    enum Opcode : uint8_t {
        kCmdNone,       ///< ignored, always acked
        kCmdTerminateSession,   ///< Terminates open Read session
        kCmdResetSessions,  ///< Terminates all open Read sessions
        kCmdListDirectory,  ///< List files in <path> from <offset>
        kCmdOpenFileRO,     ///< Opens file at <path> for reading, returns <session>
        kCmdReadFile,       ///< Reads <size> bytes from <offset> in <session>
        kCmdCreateFile,     ///< Creates file at <path> for writing, returns <session>
        kCmdWriteFile,      ///< Writes <size> bytes to <offset> in <session>
        kCmdRemoveFile,     ///< Remove file at <path>
        kCmdCreateDirectory,    ///< Creates directory at <path>
        kCmdRemoveDirectory,    ///< Removes Directory at <path>, must be empty
        kCmdOpenFileWO,     ///< Opens file at <path> for writing, returns <session>
        kCmdTruncateFile,   ///< Truncate file at <path> to <offset> length
        kCmdRename,     ///< Rename <path1> to <path2>
        kCmdCalcFileCRC32,  ///< Calculate CRC32 for file at <path>
        kCmdBurstReadFile,  ///< Burst download session file

        kRspAck = 128,      ///< Ack response
        kRspNak         ///< Nak response
    };

    /// @brief Error codes returned in Nak response PayloadHeader.data[0].
    enum ErrorCode : uint8_t {
        kErrNone,
        kErrFail,           ///< Unknown failure
        kErrFailErrno,          ///< Command failed, errno sent back in PayloadHeader.data[1]
        kErrInvalidDataSize,        ///< PayloadHeader.size is invalid
        kErrInvalidSession,     ///< Session is not currently open
        kErrNoSessionsAvailable,    ///< All available Sessions in use
        kErrEOF,            ///< Offset past end of file for List and Read commands
        kErrUnknownCommand,     ///< Unknown command opcode
        kErrFailFileExists,     ///< File exists already
        kErrFailFileProtected       ///< File is write protected
    };

    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, uint8_t target_comp_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, uint8_t target_component_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);

    /**
     * make sure that the working buffers _work_buffer* are allocated
     * @return true if buffers exist, false if allocation failed
     */
    bool _ensure_buffers_exist();

    static const char   kDirentFile = 'F';  ///< Identifies File returned from List command
    static const char   kDirentDir = 'D';   ///< Identifies Directory returned from List command
    static const char   kDirentSkip = 'S';  ///< Identifies Skipped entry from List command

    /// @brief Maximum data size in RequestHeader::data
    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;
        uint8_t         stream_target_component_id;
        unsigned    stream_chunk_transmitted;
    };
    struct SessionInfo _session_info {};    ///< Session info, fd=-1 for no active session

    ReceiveMessageFunc_t    _utRcvMsgFunc{};    ///< Unit test override for mavlink message sending
    void            *_worker_data{nullptr}; ///< Additional parameter to _utRcvMsgFunc;

    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}; ///< timestamp when the buffers were last accessed

    // 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;
};