Implements a proxy for UDP connections to a remote computer system.

TIdMappedPortUDP = class(TIdUDPServer)

TIdMappedPortUDP is a TIdUDPServer descendant that implements a proxy for connections to a remote computer system using the UDP protocol. TIdMappedPortUDP listens for connections on a designated host address and port number, and makes a surrogate connection to another server using a specified port number. This is useful for certain types of proxy programs. TIdMappedPortUDP also implements an event notification mechanism for new connection requests.

Identifies the host name or IP address for remote system.

property MappedHost: string;

MappedHost is a String property that identifies the host name or IP address for the connection to a remote system. MappedHost is used in DoUDPRead when the surrogate UDP connection is created for the current connection request.

Event handler for request to connect to a remote system.

property OnRequest: TNotifyEvent;

OnRequest is a TNotifyEvent event handler used to respond to connection requests using a surrogate UDP client connection to a remote system. Applications must assign a procedure to the event handler to allow response to the event notification.

OnRequest is triggered in DoUDPRead prior to establishing the surrogate connection to a remote system for the local UDP client.

Constructor for the object instance.

constructor Create(AOwner: TComponent); override;

Owner of the object instance.

Create is the Constructor for the object instance, and relies on the inherited Create method. Create also assigns the constant value IdPORT_DOMAIN to the DefaultPort property.

Implements transmission of data from a TStream descendant on a surrogate UDP client connection.

procedure DoUDPRead(AData: TStream; ABinding: TIdSocketHandle); override;

Stream containing data to be sent on the connection.

Socket binding generating the request.

DoUDPRead is an overridden procedure in TIdMappedPortUDP that extends the inherited method to allow transmission of data read from a TStream descendant on the surrogate UDP client connection.

DoUDPRead calls the inhertied DoUDPRead method, and generates the OnRequest event notification for the connection. DoUDPRead creates a private TIdUDPClient instance that acts as a surrogate connection to the remote system identified in MappedHost and MappedPort. DoUDPRead attempts to read all of the remaining contents in AData, transmit the data, and read any response from the remote system. If a response is received, the value is send to peer connection in ABinding.