procedure TFtpServer.TriggerStorDataAvailable(
    Client : TFtpCtrlSocket;
    Data   : TWSocket;
    Buf    : PChar;
    Len    : LongInt;
    Error  : Word);
begin
    if Assigned(FOnStorDataAvailable) then
        FOnStorDataAvailable(Self, Client, Data, Buf, Len, Error);
end;


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procedure TFtpServer.TriggerRetrDataSent(
    Client : TFtpCtrlSocket;
    Data   : TWSocket;
    Error  : Word);
begin
    if Assigned(FOnRetrDataSent) then
        FOnRetrDataSent(Self, Client, Data, Error);
end;


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procedure TFtpServer.CommandUSER(
    Client      : TFtpCtrlSocket;
    var Keyword : TFtpString;
    var Params  : TFtpString;
    var Answer  : TFtpString);
begin
    Client.CurCmdType := ftpcUSER;
    Client.UserName   := Trim(Params);
    Client.FtpState   := ftpcWaitingPassword;
    Answer            := Format(msgPassRequired, [Client.UserName]);
end;


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procedure TFtpServer.CommandPASS(
    Client      : TFtpCtrlSocket;
    var Keyword : TFtpString;
    var Params  : TFtpString;
    var Answer  : TFtpString);
var
    Authenticated : Boolean;
begin
    if Client.FtpState <> ftpcWaitingPassword then
        Answer := msgNoUser
    else begin
        Client.CurCmdType    := ftpcPASS;
        Client.PassWord      := Trim(Params);
        Authenticated        := TRUE;
        TriggerAuthenticate(Client, Client.UserName, Client.PassWord, Authenticated);
        if Authenticated then begin
            Client.FtpState  := ftpcReady;
            Client.Directory := Client.HomeDir;
            Answer           := Format(msgLogged, [Client.UserName])
        end
        else begin
            Client.FtpState  := ftpcWaitingUserCode;
            Answer           := msgLoginFailed;
        end;
    end;
end;


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procedure TFtpServer.CommandCDUP(
    Client      : TFtpCtrlSocket;
    var Keyword : TFtpString;
    var Params  : TFtpString;
    var Answer  : TFtpString);
begin
    if Client.FtpState <> ftpcReady then begin
        Answer := msgNotLogged;
        Exit;
    end;
    Client.CurCmdType := ftpcCDUP;
    Params := '..';
    CommandChangeDir(Client, Keyword, Params, Answer);
end;


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procedure TFtpServer.CommandCWD(
    Client      : TFtpCtrlSocket;
    var Keyword : TFtpString;
    var Params  : TFtpString;
    var Answer  : TFtpString);
begin
    if Client.FtpState <> ftpcReady then begin
        Answer := msgNotLogged;
        Exit;
    end;
    Client.CurCmdType    := ftpcCWD;
    CommandChangeDir(Client, Keyword, Params, Answer);
end;


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function SlashesToBackSlashes(const S : String) : String;
var
    I : Integer;
begin
    Result := S;
    for I := 1 to Length(Result) do begin
        if Result [I] = '/' then
            Result[I] := '\';
    end;
end;


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function BackSlashesToSlashes(const S : String) : String;
var
    I : Integer;
begin
    Result := S;
    for I := 1 to Length(Result) do begin
        if Result [I] = '\' then
            Result[I] := '/';
    end;
end;


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procedure TFtpServer.CommandChangeDir(
    Client      : TFtpCtrlSocket;
    var Keyword : TFtpString;
    var Params  : TFtpString;
    var Answer  : TFtpString);
var
    Allowed : Boolean;
    OldDir  : String;
begin
    OldDir := Client.Directory;
    try
        Params               := SlashesToBackSlashes(Params);
        Client.Directory     := Trim(Params);
        Allowed              := TRUE;
        TriggerChangeDirectory(Client, Client.Directory, Allowed);
        if Allowed then
            Answer           := Format(msgCWDSuccess,
                                       [BackSlashesToSlashes(Client.Directory)])
        else begin
            Client.Directory := OldDir;
            Answer           := Format(msgCWDFailed, ['No permission']);
        end;
    except
        on E:Exception do begin
            Client.Directory := OldDir;
            Answer           := Format(msgCWDFailed, [E.Message]);
        end;
    end;
end;


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procedure TFtpServer.CommandXPWD(
    Client      : TFtpCtrlSocket;
    var Keyword : TFtpString;
    var Params  : TFtpString;
    var Answer  : TFtpString);
begin
    if Client.FtpState <> ftpcReady then begin
        Answer := msgNotLogged;
        Exit;
    end;

    Client.CurCmdType := ftpcXPWD;
    Answer            := Format(msgPWDSuccess,
                                [BackSlashesToSlashes(Client.Directory)]);
end;


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procedure TFtpServer.CommandPWD(
    Client      : TFtpCtrlSocket;
    var Keyword : TFtpString;
    var Params  : TFtpString;
    var Answer  : TFtpString);
begin
    if Client.FtpState <> ftpcReady then begin
        Answer := msgNotLogged;
        Exit;
    end;

    Client.CurCmdType := ftpcPWD;
    Answer            := Format(msgPWDSuccess,
                                [BackSlashesToSlashes(Client.Directory)]);
end;


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procedure TFtpServer.CommandQUIT(
    Client      : TFtpCtrlSocket;
    var Keyword : TFtpString;
    var Params  : TFtpString;
    var Answer  : TFtpString);
begin
    Client.CurCmdType := ftpcQUIT;
    Answer            := msgQuit;
    PostMessage(FWindowHandle, WM_FTPSRV_CLOSE_REQUEST, 0, LongInt(Client));
end;


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function GetInteger(var I : Integer; const Src : String) : LongInt;
begin
    { Skip leading white spaces }
    while (I <= Length(Src)) and (Src[I] in [' ' , #9]) do
        Inc(I);
    Result := 0;
    while (I <= Length(Src)) and (Src[I] in ['0'..'9']) do begin
        Result := Result * 10 + Ord(Src[I]) - Ord('0');
        Inc(I);
    end;
    { Skip trailing white spaces }
    while (I <= Length(Src)) and (Src[I] in [' ' , #9]) do
        Inc(I);
    { Check if end of string of comma. If not, error, returns -1 }
    if I <= Length(Src) then begin
        if Src[I] = ',' then
            Inc(I)        { skip comma           }
        else
            raise Exception.Create('unexpected char'); { error, must be comma }
    end;
end;


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procedure TFtpServer.CommandPORT(
    Client      : TFtpCtrlSocket;
    var Keyword : TFtpString;
    var Params  : TFtpString;
    var Answer  : TFtpString);
var
    I : Integer;
    N : LongInt;
begin
    if Client.FtpState <> ftpcReady then begin
        Answer := msgNotLogged;
        Exit;
    end;

    try
        Client.CurCmdType := ftpcPORT;
        I                 := 1;
        Client.DataAddr   := IntToStr(GetInteger(I, Params));
        Client.DataAddr   := Client.DataAddr + '.' + IntToStr(GetInteger(I, Params));
        Client.DataAddr   := Client.DataAddr + '.' + IntToStr(GetInteger(I, Params));
        Client.DataAddr   := Client.DataAddr + '.' + IntToStr(GetInteger(I, Params));
        N := GetInteger(I, Params);
        N := (N shl 8) + GetInteger(I, Params);
        Client.DataPort := IntToStr(N);
        Answer := msgPortSuccess;
    except
        Answer := msgPortFailed;
    end;
end;


{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}
procedure TFtpServer.CommandSTOR(
    Client      : TFtpCtrlSocket;
    var Keyword : TFtpString;
    var Params  : TFtpString;
    var Answer  : TFtpString);
var
    Allowed  : Boolean;
    FilePath : TFtpString;
begin
    if Client.FtpState <> ftpcReady then begin
        Answer := msgNotLogged;
        Exit;
    end;

    try
        Client.CurCmdType       := ftpcSTOR;
        Client.FileName         := SlashesToBackSlashes(Params);
        Client.HasOpenedFile    := FALSE;
        Client.AbortingTransfer := FALSE;
        Client.TransferError    := 'Transfer Ok';
        Allowed                 := TRUE;
        FilePath                := BuildFilePath(Client.Directory, Client.FileName);
        TriggerValidatePut(Client, FilePath, Allowed);
        if not Allowed then begin
            Answer := msgStorDisabled;
            Exit;
        end;
        Client.FilePath := FilePath;
        if Client.PassiveMode then begin
            Client.DataSocket.OnSessionConnected  := ClientStorSessionConnected;
            Client.DataSocket.OnSessionClosed     := ClientStorSessionClosed;
            Client.DataSocket.OnDataAvailable     := ClientStorDataAvailable;
            Client.DataSocket.OnDataSent          := nil;
            if Client.PassiveConnected then
                Client.DataSocket.OnSessionConnected(Client.DataSocket, 0)
            else
                Client.PassiveStart := TRUE;
        end
        else begin
            Client.DataSocket.Proto               := 'tcp';
            Client.DataSocket.Addr                := Client.DataAddr;
            Client.DataSocket.Port                := Client.DataPort;
            Client.DataSocket.OnSessionConnected  := ClientStorSessionConnected;
            Client.DataSocket.OnSessionClosed     := ClientStorSessionClosed;
            Client.DataS