# Class TBlockSocket

Description | Hierarchy | Fields | Methods | Properties

## Unit

blcksock

## Declaration

`type TBlockSocket = class(TObject)`

## Description

Basic IP object.

This is parent class for other class with protocol implementations. Do not use this class directly! Use TICMPBlockSocket, TRAWBlockSocket, TTCPBlockSocket or TUDPBlockSocket instead.

## Hierarchy

TBlockSocket > TObject

## Methods

### Overview

| `constructor Create;`
| `constructor CreateAlternate(Stub: string);`
| `destructor Destroy; override;`
| `class function GetErrorDesc(ErrorCode: Integer): string;`
| `procedure AbortSocket; virtual;`
| `procedure Bind(IP, Port: string);`
| `function CanRead(Timeout: Integer): Boolean; virtual;`
| `function CanReadEx(Timeout: Integer): Boolean; virtual;`
| `function CanWrite(Timeout: Integer): Boolean; virtual;`
| `procedure CloseSocket; virtual;`
| `procedure Connect(IP, Port: string); virtual;`
| `procedure CreateSocket;`
| `procedure CreateSocketByName(const Value: String);`
| `procedure EnableReuse(Value: Boolean);`
| `procedure ExceptCheck;`
| `function GetLocalSinIP: string; virtual;`
| `function GetLocalSinPort: Integer; virtual;`
| `function GetRemoteSinIP: string; virtual;`
| `function GetRemoteSinPort: Integer; virtual;`
| `procedure GetSinLocal;`
| `procedure GetSinRemote;`
| `procedure GetSins;`
| `function GetSocketProtocol: integer; Virtual;`
| `function GetSocketType: integer; Virtual;`
| `function GroupCanRead(const SocketList: TList; Timeout: Integer; const CanReadList: TList): Boolean;`
| `function IP6ToStr(const value: TSockAddrIn6): string;`
| `function LocalName: string;`
| `function PeekBuffer(Buffer: TMemory; Length: Integer): Integer; virtual;`
| `function PeekByte(Timeout: Integer): Byte; virtual;`
| `procedure Purge;`
| `function RecvBlock(Timeout: Integer): AnsiString; virtual;`
| `function RecvBuffer(Buffer: TMemory; Length: Integer): Integer; virtual;`
| `function RecvBufferEx(Buffer: Tmemory; Len: Integer; Timeout: Integer): Integer; virtual;`
| `function RecvBufferFrom(Buffer: TMemory; Length: Integer): Integer; virtual;`
| `function RecvBufferStr(Length: Integer; Timeout: Integer): AnsiString; virtual;`
| `function RecvByte(Timeout: Integer): Byte; virtual;`
| `function RecvInteger(Timeout: Integer): Integer; virtual;`
| `function RecvPacket(Timeout: Integer): AnsiString; virtual;`
| `procedure RecvStream(const Stream: TStream; Timeout: Integer); virtual;`
| `procedure RecvStreamIndy(const Stream: TStream; Timeout: Integer); virtual;`
| `procedure RecvStreamRaw(const Stream: TStream; Timeout: Integer); virtual;`
| `procedure RecvStreamSize(const Stream: TStream; Timeout: Integer; Size: Integer);`
| `function RecvString(Timeout: Integer): AnsiString; virtual;`
| `function RecvTerminated(Timeout: Integer; const Terminator: AnsiString): AnsiString; virtual;`
| `function ResolveIPToName(IP: string): string;`
| `function ResolveName(Name: string): string;`
| `procedure ResolveNameToIP(Name: string; const IPList: TStrings);`
| `function ResolvePort(Port: string): Word;`
| `procedure SendBlock(const Data: AnsiString); virtual;`
| `function SendBuffer(Buffer: Tmemory; Length: Integer): Integer; virtual;`
| `function SendBufferTo(Buffer: TMemory; Length: Integer): Integer; virtual;`
| `procedure SendByte(Data: Byte); virtual;`
| `procedure SendInteger(Data: integer); virtual;`
| `procedure SendStream(const Stream: TStream); virtual;`
| `procedure SendStreamIndy(const Stream: TStream); virtual;`
| `procedure SendStreamRaw(const Stream: TStream); virtual;`
| `procedure SendString(Data: AnsiString); virtual;`
| `procedure SetLinger(Enable: Boolean; Linger: Integer);`
| `procedure SetRecvTimeout(Timeout: Integer);`
| `procedure SetRemoteSin(IP, Port: string);`
| `procedure SetSendTimeout(Timeout: Integer);`
| `procedure SetTimeout(Timeout: Integer);`
| `function SockCheck(SockResult: Integer): Integer;`
| `function StrToIP6(const value: string): TSockAddrIn6;`
| `function WaitingData: Integer; virtual;`
| `function WaitingDataEx: Integer;`

### Description

| `procedure AbortSocket; virtual;`

Abort any work on Socket and destroy them.

| `procedure Bind(IP, Port: string);`

Connects socket to local IP address and PORT. IP address may be numeric or symbolic ('192.168.74.50', 'cosi.nekde.cz', 'ff08::1'). The same for PORT - it may be number or mnemonic port ('23', 'telnet').

If port value is '0', system chooses itself and conects unused port in the range 1024 to 4096 (this depending by operating system!). Structure LocalSin is filled after calling this method.

Note: If you call this on non-created socket, then socket is created automaticly.

Warning: when you call : Bind('0.0.0.0','0'); then is nothing done! In this case is used implicit system bind instead.

| `function CanRead(Timeout: Integer): Boolean; virtual;`

Return `True`, if you can read any data from socket or is incoming connection on TCP based socket. Status is tested for time Timeout (in milliseconds). If value in Timeout is 0, status is only tested and continue. If value in Timeout is -1, run is breaked and waiting for read data maybe forever.

This function is need only on special cases, when you need use RecvBuffer function directly!

| `function CanReadEx(Timeout: Integer): Boolean; virtual;`

Same as CanRead, but additionally return `True` if is some data in LineBuffer.

| `function CanWrite(Timeout: Integer): Boolean; virtual;`

Return `True`, if you can to socket write any data (not full sending buffer). Status is tested for time Timeout (in milliseconds). If value in Timeout is 0, status is only tested and continue. If value in Timeout is -1, run is breaked and waiting for write data maybe forever.

This function is need only on special cases!

| `procedure CloseSocket; virtual;`

Destroy socket in use. This method is also automatically called from object destructor.

| `procedure Connect(IP, Port: string); virtual;`

Connects socket to remote IP address and PORT. The same rules as with Bind method are valid. The only exception is that PORT with 0 value will not be connected!

Structures LocalSin and RemoteSin will be filled with valid values.

When you call this on non-created socket, then socket is created automaticly. Type of created socket is by Family property. If is used SF_IP4, then is created socket for IPv4. If is used SF_IP6, then is created socket for IPv6. When you have family on SF_Any (default!), then type of created socket is determined by address resolving of destination address. (Not work properly on prilimitary winsock IPv6 support!)

| `constructor Create;`

| `constructor CreateAlternate(Stub: string);`

Create object and load all necessary socket library. What library is loaded is described by STUB parameter. If STUB is empty string, then is loaded default libraries.

| `procedure CreateSocket;`

If Family is not SF_Any, then create socket with type defined in Family property. If family is SF_Any, then do nothing! (socket is created automaticly when you know what type of socket you need to create. (i.e. inside Connect or Bind call.) When socket is created, then is aplyed all stored delayed socket options.

| `procedure CreateSocketByName(const Value: String);`

It create socket. Address resolving of Value tells what type of socket is created. If Value is resolved as IPv4 IP, then is created IPv4 socket. If value is resolved as IPv6 address, then is created IPv6 socket.

| `destructor Destroy; override;`

| `procedure EnableReuse(Value: Boolean);`

By this method you may turn address reuse mode for local Bind. It is good specially for UDP protocol. Using this with TCP protocol is hazardous!

| `procedure ExceptCheck;`

If LastError contains some error code and RaiseExcept property is `True`, raise adequate exception.

| `class function GetErrorDesc(ErrorCode: Integer): string;`

Return descriptive string for given error code. This is class function. You may call it without created object!

| `function GetLocalSinIP: string; virtual;`

Picks IP socket address from LocalSin.

| `function GetLocalSinPort: Integer; virtual;`

Picks socket PORT number from LocalSin.

| `function GetRemoteSinIP: string; virtual;`

Picks IP socket address from RemoteSin.

| `function GetRemoteSinPort: Integer; virtual;`

Picks socket PORT number from RemoteSin.

| `procedure GetSinLocal;`

Actualize values in LocalSin.

| `procedure GetSinRemote;`

Actualize values in RemoteSin.

| `procedure GetSins;`

Actualize values in LocalSin and RemoteSin.

| `function GetSocketProtocol: integer; Virtual;`

Return value of protocol type for socket creation.

| `function GetSocketType: integer; Virtual;`

Return value of socket type.

| `function GroupCanRead(const SocketList: TList; Timeout: Integer; const CanReadList: TList): Boolean;`

This function is for check for incoming data on set of sockets. Whitch sockets is checked is decribed by SocketList Tlist with TBlockSocket objects. TList may have maximal number of objects defined by FD_SETSIZE constant. Return `True`, if you can from some socket read any data or is incoming connection on TCP based socket. Status is tested for time Timeout (in milliseconds). If value in Timeout is 0, status is only tested and continue. If value in Timeout is -1, run is breaked and waiting for read data maybe forever. If is returned `True`, CanReadList TList is filled by all TBlockSocket objects what waiting for read.

| `function IP6ToStr(const value: TSockAddrIn6): string;`

Convert IPv6 address from binary to string form. This function working only on systems with IPv6 support!

| `function LocalName: string;`

Returns local computer name as numerical or symbolic value. It try get fully qualified domain name. Name is returned in the format acceptable by functions demanding IP as input parameter.

| `function PeekBuffer(Buffer: TMemory; Length: Integer): Integer; virtual;`

Same as RecvBuffer, but readed data stays in system input buffer. Warning: this function not respect data in LineBuffer! Is not recommended to use this function!

| `function PeekByte(Timeout: Integer): Byte; virtual;`

Same as RecvByte, but readed data stays in input system buffer. Warning: this function not respect data in LineBuffer! Is not recommended to use this function!

| `procedure Purge;`

Clear all waiting data for read from buffers.

| `function RecvBlock(Timeout: Integer): AnsiString; virtual;`

Read one block of data from socket. Each block begin with 4 bytes with length of data in block. This function read first 4 bytes for get lenght, then it wait for reported count of bytes.

| `function RecvBuffer(Buffer: TMemory; Length: Integer): Integer; virtual;`

Note: This is low-level receive function. You must be sure if data is waiting for read before call this function for avoid deadlock!

Waits until allocated buffer is filled by received data. Returns number of data received, which equals to LENGTH value under normal operation. If it is not equal the communication channel is possibly broken.

On stream oriented sockets if is received 0 bytes, it mean 'socket is closed!"

On datagram socket is readed first waiting datagram.

| `function RecvBufferEx(Buffer: Tmemory; Len: Integer; Timeout: Integer): Integer; virtual;`

Note: This is high-level receive function. It using internal LineBuffer and you can combine this function freely with other high-level functions!

Method waits until data is received. If no data is received within TIMEOUT (in milliseconds) period, LastError is set to WSAETIMEDOUT. Methods serves for reading any size of data (i.e. one megabyte...). This method is preffered for reading from stream sockets (like TCP).

| `function RecvBufferFrom(Buffer: TMemory; Length: Integer): Integer; virtual;`

Note: This is low-lever receive function. You must be sure if data is waiting for read before call this function for avoid deadlock!

Receives first waiting datagram to allocated buffer. If there is no waiting one, then waits until one comes. Returns length of datagram stored in BUFFER. If length exceeds buffer datagram is truncated. After this RemoteSin structure contains information about sender of UDP packet.

| `function RecvBufferStr(Length: Integer; Timeout: Integer): AnsiString; virtual;`

Similar to RecvBufferEx, but readed data is stored in binary string, not in memory buffer.

| `function RecvByte(Timeout: Integer): Byte; virtual;`

Note: This is high-level receive function. It using internal LineBuffer and you can combine this function freely with other high-level functions.

Waits until one data byte is received which is also returned as function result. If no data is received within TIMEOUT (in milliseconds)period, LastError is set to WSAETIMEDOUT and result have value 0.

| `function RecvInteger(Timeout: Integer): Integer; virtual;`

Note: This is high-level receive function. It using internal LineBuffer and you can combine this function freely with other high-level functions.

Waits until one four bytes are received and return it as one Ineger Value. If no data is received within TIMEOUT (in milliseconds)period, LastError is set to WSAETIMEDOUT and result have value 0.

| `function RecvPacket(Timeout: Integer): AnsiString; virtual;`

Note: This is high-level receive function. It using internal LineBuffer and you can combine this function freely with other high-level functions.

Method reads all data waiting for read. If no data is received within TIMEOUT (in milliseconds) period, LastError is set to WSAETIMEDOUT. Methods serves for reading unknown size of data. Because before call this function you don't know size of received data, returned data is stored in dynamic size binary string. This method is preffered for reading from stream sockets (like TCP). It is very goot for receiving datagrams too! (UDP protocol)

| `procedure RecvStream(const Stream: TStream; Timeout: Integer); virtual;`

Receive data to stream. It using RecvBlock method.

| `procedure RecvStreamIndy(const Stream: TStream; Timeout: Integer); virtual;`

Receive data to stream. This function is compatible with similar function in Indy library. It using RecvBlock method.

| `procedure RecvStreamRaw(const Stream: TStream; Timeout: Integer); virtual;`

Read all data from socket to stream until socket is closed (or any error occured.)

| `procedure RecvStreamSize(const Stream: TStream; Timeout: Integer; Size: Integer);`

Read requested count of bytes from socket to stream.

| `function RecvString(Timeout: Integer): AnsiString; virtual;`

Note: This is high-level receive function. It using internal LineBuffer and you can combine this function freely with other high-level functions.

Method waits until data string is received. This string is terminated by CR-LF characters. The resulting string is returned without this termination (CR-LF)! If ConvertLineEnd is used, then CR-LF sequence may not be exactly CR-LF. See ConvertLineEnd description. If no data is received within TIMEOUT (in milliseconds) period, LastError is set to WSAETIMEDOUT. You may also specify maximum length of reading data by MaxLineLength property.

| `function RecvTerminated(Timeout: Integer; const Terminator: AnsiString): AnsiString; virtual;`

Note: This is high-level receive function. It using internal LineBuffer and you can combine this function freely with other high-level functions.

Method waits until data string is received. This string is terminated by Terminator string. The resulting string is returned without this termination. If no data is received within TIMEOUT (in milliseconds) period, LastError is set to WSAETIMEDOUT. You may also specify maximum length of reading data by MaxLineLength property.

| `function ResolveIPToName(IP: string): string;`

Try resolve IP to their primary domain name. If IP not have domain name, then is returned original IP.

| `function ResolveName(Name: string): string;`

Try resolve name to primary IP address. i.e. If you pass as name result of LocalName method, you get primary IP addresses used by local system.

| `procedure ResolveNameToIP(Name: string; const IPList: TStrings);`

Try resolve name to all possible IP address. i.e. If you pass as name result of LocalName method, you get all IP addresses used by local system.

| `function ResolvePort(Port: string): Word;`

Try resolve symbolic port name to port number. (i.e. 'Echo' to 8)

| `procedure SendBlock(const Data: AnsiString); virtual;`

Send data as one block to socket. Each block begin with 4 bytes with length of data in block. This 4 bytes is added automaticly by this function.

| `function SendBuffer(Buffer: Tmemory; Length: Integer): Integer; virtual;`

Sends data of LENGTH from BUFFER address via connected socket. System automatically splits data to packets.

| `function SendBufferTo(Buffer: TMemory; Length: Integer): Integer; virtual;`

Same as SendBuffer, but send datagram to address from RemoteSin. Usefull for sending reply to datagram received by function RecvBufferFrom.

| `procedure SendByte(Data: Byte); virtual;`

One data BYTE is sent via connected socket.

| `procedure SendInteger(Data: integer); virtual;`

Send integer as four bytes to socket.

| `procedure SendStream(const Stream: TStream); virtual;`

Send content of stream to socket. It using SendBlock method

| `procedure SendStreamIndy(const Stream: TStream); virtual;`

Send content of stream to socket. It using SendBlock method and this is compatible with streams in Indy library.

| `procedure SendStreamRaw(const Stream: TStream); virtual;`

Send data from stream to socket.

| `procedure SendString(Data: AnsiString); virtual;`

Send data string via connected socket. Any terminator is not added! If you need send true string with CR-LF termination, you must add CR-LF characters to sended string! Because any termination is not added automaticly, you can use this function for sending any binary data in binary string.

| `procedure SetLinger(Enable: Boolean; Linger: Integer);`

Sets linger. Enabled linger means that the system waits another LINGER (in milliseconds) time for delivery of sent data. This function is only for stream type of socket! (TCP)

| `procedure SetRecvTimeout(Timeout: Integer);`

Try set timeout for all receiving operations, if socket provider can do it. (It not supported by all socket providers!)

| `procedure SetRemoteSin(IP, Port: string);`

Set information about remote side socket. It is good for seting remote side for sending UDP packet, etc.

| `procedure SetSendTimeout(Timeout: Integer);`

Try set timeout for all sending operations, if socket provider can do it. (It not supported by all socket providers!)

| `procedure SetTimeout(Timeout: Integer);`

Try set timeout for all sending and receiving operations, if socket provider can do it. (It not supported by all socket providers!)

| `function SockCheck(SockResult: Integer): Integer;`

If you "manually" call Socket API functions, forward their return code as parameter to this function, which evaluates it, eventually calls GetLastError and found error code returns and stores to LastError.

| `function StrToIP6(const value: string): TSockAddrIn6;`

Convert IPv6 address from their string form to binary. This function working only on systems with IPv6 support!

| `function WaitingData: Integer; virtual;`

On stream sockets it returns number of received bytes waiting for picking. 0 is returned when there is no such data. On datagram socket it returns length of the first waiting datagram. Returns 0 if no datagram is waiting.

| `function WaitingDataEx: Integer;`

Same as WaitingData, but if exists some of data in LineBuffer, return their length instead.

## Properties

### Overview

| `property ConvertLineEnd: Boolean;`
| `property Family: TSocketFamily;`
| `property InterPacketTimeout: Boolean;`
| `property IP6used: Boolean;`
| `property LastError: Integer;`
| `property LastErrorDesc: string;`
| `property LineBuffer: string;`
| `property LocalSin: TVarSin;`
| `property MaxBandwidth: Integer;`
| `property MaxLineLength: Integer;`
| `property MaxRecvBandwidth: Integer;`
| `property MaxSendBandwidth: Integer;`
| `property NonBlockMode: Boolean;`
| `property OnCreateSocket: THookCreateSocket;`
| `property OnReadFilter: THookDataFilter;`
| `property OnStatus: THookSocketStatus;`
| `property OnWriteFilter: THookDataFilter;`
| `property PreferIP4: Boolean;`
| `property RaiseExcept: Boolean;`
| `property RecvCounter: Integer;`
| `property RemoteSin: TVarSin;`
| `property SendCounter: Integer;`
| `property SendMaxChunk: Integer;`
| `property SizeRecvBuffer: Integer;`
| `property SizeSendBuffer: Integer;`
| `property Socket: TSocket;`
| `property StopFlag: Boolean;`
| `property Tag: Integer;`
| `property TTL: Integer;`
| `property WSAData: TWSADATA;`

### Description

| `property ConvertLineEnd: Boolean;`

Do a conversion of non-standard line terminators to CRLF. (Off by default) If `True`, then terminators like sigle CR, single LF or LFCR are converted to CRLF internally. This have effect only in RecvString method!

| `property Family: TSocketFamily;`

Specified Family of this socket. When you are using Windows preliminary support for IPv6, then I recommend to set this property!

| `property InterPacketTimeout: Boolean;`

By dafault (`False`) is all timeouts used as timeout between two packets in reading operations. If you set this to `True`, then Timeouts is for overall reading operation!

| `property IP6used: Boolean;`

If is `True`, then class in in IPv6 mode.

| `property LastError: Integer;`

Last socket operation error code. Error codes are described in socket documentation. Human readable error description is stored in LastErrorDesc property.

| `property LastErrorDesc: string;`

Human readable error description of LastError code.

| `property LineBuffer: string;`

Buffer used by all high-level receiving functions. This buffer is used for optimized reading of data from socket. In normal cases you not need access to this buffer directly!

| `property LocalSin: TVarSin;`

Structure describing local socket side.

| `property MaxBandwidth: Integer;`

Define maximal bandwidth for all sending and receiving operations in bytes per second. If value is 0 (default), bandwidth limitation is not used.

| `property MaxLineLength: Integer;`

Define maximum length in bytes of LineBuffer for high-level receiving functions. If this functions try to read more data then this limit, error is returned! If value is 0 (default), no limitation is used. This is very good protection for stupid attacks to your server by sending lot of data without proper terminator... until all your memory is allocated by LineBuffer!

Note: This maximum length is checked only in functions, what read unknown number of bytes! (like RecvString or RecvTerminated)

| `property MaxRecvBandwidth: Integer;`

Define maximal bandwidth for all receiving operations in bytes per second. If value is 0 (default), bandwidth limitation is not used.

| `property MaxSendBandwidth: Integer;`

Define maximal bandwidth for all sending operations in bytes per second. If value is 0 (default), bandwidth limitation is not used.

| `property NonBlockMode: Boolean;`

If `True`, turn class to non-blocking mode. Not all functions are working properly in this mode, you must know exactly what you are doing! However when you have big experience with non-blocking programming, then you can optimise your program by non-block mode!

| `property OnCreateSocket: THookCreateSocket;`

This event is called after real socket creation for setting special socket options, because you not know when socket is created. (it is depended on Ipv4, IPv6 or automatic mode)

| `property OnReadFilter: THookDataFilter;`

this event is good for some internal thinks about filtering readed datas. It is used by telnet client by example.

| `property OnStatus: THookSocketStatus;`

This event is called by various reasons. It is good for monitoring socket, create gauges for data transfers, etc.

| `property OnWriteFilter: THookDataFilter;`

This event is good for some internal thinks about filtering writed datas.

| `property PreferIP4: Boolean;`

When resolving of domain name return both IPv4 and IPv6 addresses, then specify if is used IPv4 (dafault - `True`) or IPv6.

| `property RaiseExcept: Boolean;`

If `True`, winsock errors raises exception. Otherwise is setted LastError value only and you must check it from your program! Default value is `False`.

| `property RecvCounter: Integer;`

Return count of received bytes on this socket from begin of current connection.

| `property RemoteSin: TVarSin;`

Structure describing remote socket side.

| `property SendCounter: Integer;`

Return count of sended bytes on this socket from begin of current connection.

| `property SendMaxChunk: Integer;`

All sended datas was splitted by this value.

| `property SizeRecvBuffer: Integer;`

Size of Winsock receive buffer. If it is not supported by socket provider, it return as size one kilobyte.

| `property SizeSendBuffer: Integer;`

Size of Winsock send buffer. If it is not supported by socket provider, it return as size one kilobyte.

| `property Socket: TSocket;`

Socket handler. Suitable for "manual" calls to socket API or manual connection of socket to a previously created socket (i.e by Accept method on TCP socket)

| `property StopFlag: Boolean;`

By setting this property to `True` you can stop any communication. You can use this property for soft abort of communication.

| `property Tag: Integer;`

this value is for free use.

| `property TTL: Integer;`

Set Time-to-live value. (if system supporting it!)

| `property WSAData: TWSADATA;`

WSA structure with information about socket provider. On linux is this structure simulated!

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