idintercept.pas

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{ $Log:  11944: IdIntercept.pas 
{
{   Rev 1.8    2004.02.03 4:16:44 PM  czhower
{ For unit name changes.
}
{
{   Rev 1.7    2004.01.20 10:03:24 PM  czhower
{ InitComponent
}
{
{   Rev 1.6    5/12/2003 12:33:32 AM  GGrieve
{ add Data from BlockCipher descendent
}
{
{   Rev 1.5    2003.10.14 1:26:48 PM  czhower
{ Uupdates + Intercept support
}
{
{   Rev 1.4    2003.10.11 5:48:16 PM  czhower
{ -VCL fixes for servers
{ -Chain suport for servers (Super core)
{ -Scheduler upgrades
{ -Full yarn support
}
{
{   Rev 1.3    10/5/2003 3:20:46 PM  BGooijen
{ .net
}
{
{   Rev 1.2    2003.10.01 1:12:34 AM  czhower
{ .Net
}
{
    Rev 1.1    3/5/2003 10:59:48 PM  BGooijen
  Fixed (i know, the SendBuffer looks bad)
}
{
{   Rev 1.0    11/13/2002 08:44:42 AM  JPMugaas
}
unit IdIntercept;
{
2002-03-01 - Andrew P.Rybin
  - Nested Intercept support (ex: ->logging->compression->encryption)
2002-04-09 - Chuck Smith
  - set ABuffer.Position := 0; in OnSend/OnReceive for Nested Stream send/receive
}
interface

uses
  Classes,
  IdGlobal, IdBaseComponent, IdBuffer, IdException;

type
  EIdInterceptCircularLink = class(EIdException);
  TIdConnectionIntercept = class;
  TIdInterceptNotifyEvent = procedure(ASender: TIdConnectionIntercept) of object;
  TIdInterceptStreamEvent = procedure(
    ASender: TIdConnectionIntercept;
    var ABuffer: TIdBytes
    ) of object;

  TIdConnectionIntercept = class(TIdBaseComponent)
  protected
    FConnection: TComponent;
    FIntercept: TIdConnectionIntercept;
    FIsClient: Boolean;
    FData: TObject;

    FOnConnect: TIdInterceptNotifyEvent;
    FOnDisconnect: TIdInterceptNotifyEvent;
    FOnReceive: TIdInterceptStreamEvent;
    FOnSend: TIdInterceptStreamEvent;
    //
    procedure InitComponent; override;
    procedure Notification(AComponent: TComponent; Operation: TOperation); override;
    procedure SetIntercept(AValue: TIdConnectionIntercept);
    //
    property Intercept: TIdConnectionIntercept read FIntercept write SetIntercept;
  public
    procedure Connect(AConnection: TComponent); virtual;
    procedure Disconnect;
      virtual;
    procedure Receive(
      var ABuffer: TIdBytes
      ); virtual;
    procedure Send(
      var ABuffer: TIdBytes
      ); virtual;
    //
    property Connection: TComponent read FConnection;
    property IsClient: Boolean read FIsClient;
    property Data: TObject read FData write FData; // user can use this to keep context
  published
    property OnConnect: TIdInterceptNotifyEvent read FOnConnect write FOnConnect;
    property OnDisconnect: TIdInterceptNotifyEvent read FOnDisconnect write FOnDisconnect;
    property OnReceive: TIdInterceptStreamEvent read FOnReceive write FOnReceive;
    property OnSend: TIdInterceptStreamEvent read FOnSend write FOnSend;
  end;

  TIdServerIntercept = class(TIdBaseComponent)
  public
    procedure Init; virtual; abstract;
    function Accept(AConnection: TComponent): TIdConnectionIntercept; virtual; abstract;
  end;

implementation
uses
  IdResourceStringsCore,
  SysUtils;

{ TIdIntercept }

procedure TIdConnectionIntercept.Disconnect;
begin
  if Intercept <> nil then begin
    Intercept.Disconnect;
  end;
  if Assigned(OnDisconnect) then begin
    OnDisconnect(Self);
  end;
  FConnection := nil;
end;

procedure TIdConnectionIntercept.Connect(AConnection: TComponent);
begin
  FConnection := AConnection;
  if Assigned(OnConnect) then begin
    OnConnect(Self);
  end;
  if Intercept <> nil then begin
    Intercept.Connect(AConnection);
  end;
end;

procedure TIdConnectionIntercept.Receive(var ABuffer: TIdBytes);
begin
  if Intercept <> nil then begin
    Intercept.Receive(ABuffer);
  end;
  if Assigned(OnReceive) then begin
    OnReceive(Self, ABuffer);
  end;
end;

procedure TIdConnectionIntercept.Send(var ABuffer: TIdBytes);
begin
  if Assigned(OnSend) then begin
    OnSend(Self, ABuffer);
  end;
  if Intercept <> nil then begin
    Intercept.Send(ABuffer);
  end;
end;

procedure TIdConnectionIntercept.SetIntercept(AValue: TIdConnectionIntercept);
var
  LIntercept: TIdConnectionIntercept;
Begin
  LIntercept := AValue;
  while Assigned(LIntercept) do begin
    if LIntercept = SELF then begin //recursion
      raise EIdInterceptCircularLink.Create(Format(RSInterceptCircularLink,[ClassName])); // TODO: Resource string and more english
    end;
    LIntercept := LIntercept.Intercept;
  end;

  Intercept := AValue;
  // add self to the Intercept's free notification list    {Do not Localize}
  if Assigned(Intercept) then begin
    Intercept.FreeNotification(Self);
  end;
End;

procedure TIdConnectionIntercept.Notification(AComponent: TComponent;
  Operation: TOperation);
begin
  inherited Notification(AComponent, OPeration);

  if (Operation = opRemove) and (AComponent = Intercept) then begin
    FIntercept := NIL;
  end;
end;

procedure TIdConnectionIntercept.InitComponent;
begin
  inherited;
  FIsClient := True;
end;

end.