Implements an input and output handler using socket handles.

TIdIOHandlerSocket = class(TIdIOHandler)

TIdIOHandlerSocket is a TIdIOHandler descendant that implements the framework used to perform input and output operations for Indy components using a socket handle as the source or destination.

TIdIOHandlerSocket implements abstract virtual methods inherited from TIdIOHandler that allow the handler to prepare and establish a connection to remote computer system, determine when the handler is ready to perform an IO operation, and perform the data transmission or receipt required for a component.

TIdIOHandlerSocket also exposes properties that allow acccess to the Binding for the socket connection, and use of the Nagle algorithm while performing IO operations.

Represents the socket handle used for a connection.

property Binding: TIdSocketHandle;

Binding is a read-only TIdSocketHandle property that represents the socket handle used for a connection to another computer system. Binding provides the mechanism used to determine when the handler is ready to perform its IO operation, and the physical conduit used in calls to the Send and Recv methods.

Use Open to insure that the Binding contains a valid socket handle data type.

Use ConnectClient to allocate the socket handle in Binding, and to spawn a TIdConnectThread that establishes the connection using Socks proxy and Timeout input parameters.

Use Close to insure that Binding is disconnected and freed.

Implements support for proxied client connection in the IO handler.

property SocksInfo: TIdSocksInfo;

SocksInfo is a TIdSocksInfo property that provides support for proxied client connections for the system identified in Host and Port. SocksInfo is used when ConnectClient is called to establish the client connection to a remote computer system, and provides the actual Host address and port number used for the client connection for SOCKS version 4 and 5 support using the TIdSocksInfo.MakeSocksConnection method.

Reading the value of SocksInfo will insure that an object instance is created at runtime when a SocksInfo has not been assigned for the IO Handler.

Assigning SocksInfo for the IO Handler will insure that a previous TIdSocksInfo object instance, created at runtime or owned by a different form than the current object, is freed and released prior to assigning the new value.

SocksInfo will be freed in Destroy when the object instance has been created at runtime and theowner form has not been assigned.

Indicates the socket connection can use the Nagle algorithm.

property UseNagle: boolean;

UseNagle is a Boolean property that indicates if the socket connection in Binding can use the Nagle algorithm for send coalescing during output operations to the handle. The default value for UseNagle is True, as assigned in the Create constructor.

UseNagle is used in ConnectClient to determine if the Binding must set socket options that reflect the use of the algorithm during output operations.

Closes and frees the socket handle used for input/output operations.

procedure Close; override;

Close is an overridden procedure that closes and frees the socket handle in Binding used for input and output operations. Use Open to insure that the Binding contains a valid socket handle data type. Use ConnectClient to allocate the socket handle in Binding, and to spawn a TIdConnectThread that establishes the connection using Socks proxy and Timeout input parameters.

Establisheds a remote connection for the input/output handler.

procedure ConnectClient(const AHost: string; const APort: Integer; const ABoundIP: string; const ABoundPort: Integer; const ABoundPortMin: Integer; const ABoundPortMax: Integer; const ATimeout: Integer = IdTimeoutDefault); override;

Address of the remote system for the client connection.

Port number for the remote connection.

IP Address bound to the local system.

Port number bound to the local computer.

Minimum bound port number for the local system.

Maximum bound port number for the local system.

Number of milliseconds to wait before a connection attempt fails. Default value is IdTimeoutDefault.

ConnectClient is an overriden procedure in TIdIOHandlerSocket that implements the mechanism that allows an input/output handler to prepare and establish a client connection to a remote computer system using the input parameters.

ConnectClient calls the inherited ConnectClient method, allocates and Binds the socket handle in Binding using the values specified in ABoundIP, ABoundPort, ABoundPortMin, and ABoundPortMax.

If the value in AHost is a host name instead of an IP address, ConnectClient will trigger the OnStatus event to indicate that the address will be resolved prior to setting the peer address and port number for the physical connection in Binding.

ConnectClient will also set the socket options required for UseNage support.

ConnectClient also triggers the OnStatus event handler to indicate that the connection will be opened to the peer client connection prior to trying to open the connection with the timeout value specified in ATimeout.

ConnectClient uses a thread to connect to the remote computer system to allow use of a timeout value in Connect while respecting the operation of the TIdAntifreeze component when present. If the connection thread is terminated with an exception message, ConnectClient can raise an EIdConnectException exception with the exception messasge from the threaded connection. If the connection thread is terminated without an exception message prior to being Connected, ConnectClient can raise an EIdConnectTimeout exception.

Use Connected to detemine if the physical connection has been established after a call to ConnectClient.

Indicates if the physical connection for the handler is prepared and opened.

function Connected: Boolean; override;

Boolean - True when the handler connection is prepared and opened.

Connected is an overriden Boolean function in TIdIOHandlerSocket that implements the method used to determine when the physical connection for the handler has been established, and is available for input/output operations.

Connected will indicate when the socket handle in Binding has been assigned and allocated.

Use Open to prepare the physical connection for the handler, and ConnectClient to establish the connection used by the handler.

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 constructor. Create also sets the default value of UseNagle to True, to indicate that use of the Nagle algorithm for send coalescing is allowed.

Frees the object instance.

destructor Destroy; override;

Destroy is the destructor for the object instance. Destroy will free and release resources allocated to SocksInfo when it has been created at runtime without an owner form. Destroy calls the inherited Destroy method prior to exiting.

Prepares an input/output source for the handler.

procedure Open; override;

Open is a overridden procedure that prepares an input/output source for the handler. Open calls the inherited Open method, and will insure that the socket handle in Binding for the physical connection has been assigned.

Use ConnectClient to establish the connection on the coket handle used by the handler.

Indicates that the socket handle is ready to read data.

function Readable(AMSec: integer = IdTimeoutDefault): boolean; override;

Milliseconds to wait for the socket connection to become ready. Default value is IdTimeoutDefault.

Boolean - True when ready.

Readable is an overidden Boolean function that indicates if the socket handle in Binding is ready for input operations. Readable uses Binding to call the Readable method in the TIdSocketHandle object property with the value specified in AMSec.

Use Recv to perform the input operation using the socket handle in Binding.

Performs an input operation using a socket handle.

function Recv(var ABuf; ALen: integer): integer; override;

Destination buffer for values read from the connection.

Number of bytes to read from the connection.

Integer - Acutal number of bytes read from the connection.

Recv is an overridden Integer function that performs an input operation using the socket handle in Binding. Recv calls the TIdSocketHandle.Recv method, using the input parameters ABuf and ALen, to perform the read operation.

ABuf is the destination for values read from the socket handle in Binding.

ALen indicates the number of bytes expected from the input operation.

The return value for the method is the actual number of bytes read using the socket handle.

Performs an output operation using a socket handle.

function Send(var ABuf; ALen: integer): integer; override;

Values to be written on the connection.

Number of bytes to be written on the connection.

Integer - Acutal number of bytes written using the connection.

Send is an overridden Integer function that performs an output operation using the socket handle in Binding. Send calls the TIdSocketHandle.Send method, using the input parameters ABuf and ALen, to perform the write operation.

ABuf is the buffer containing values to be written to the socket handle in Binding.

ALen indicates the number of bytes to be written in the output operation.

The return value for the method is the actual number of bytes written using the socket handle.