# Poco::Net

# class DialogSocket

Library: Net
Package: Sockets
Header: Poco/Net/DialogSocket.h

## Description

DialogSocket is a subclass of StreamSocket that can be used for implementing request-response based client server connections.

A request is always a single-line command terminated by CR-LF.

A response can either be a single line of text terminated by CR-LF, or multiple lines of text in the format used by the FTP and SMTP protocols.

Limited support for the TELNET protocol (RFC 854) is available.

Warning: Do not call receiveBytes() on a DialogSocket. Due to internal buffering in DialogSocket, receiveBytes() may return an unexpected result and interfere with DialogSocket's buffering. Use receiveRawBytes() instead.

## Inheritance

Direct Base Classes: StreamSocket

All Base Classes: Socket, StreamSocket

## Member Summary

Member Functions: allocBuffer, get, operator =, peek, receiveLine, receiveMessage, receiveRawBytes, receiveStatusLine, receiveStatusMessage, refill, sendByte, sendMessage, sendString, sendTelnetCommand, synch

Inherited Functions: address, available, bind, close, connect, connectNB, destroyBufVec, error, fromFileDescriptor, getBlocking, getError, getKeepAlive, getLinger, getNoDelay, getOOBInline, getOption, getReceiveBufferSize, getReceiveTimeout, getReuseAddress, getReusePort, getSendBufferSize, getSendTimeout, impl, init, isDatagram, isNull, isRaw, isStream, lastError, lastErrorDesc, makeBufVec, makeBuffer, operator !=, operator <, operator <=, operator =, operator ==, operator >, operator >=, peerAddress, poll, receiveBytes, secure, select, sendBytes, sendFile, sendUrgent, setBlocking, setKeepAlive, setLinger, setNoDelay, setOOBInline, setOption, setReceiveBufferSize, setReceiveTimeout, setReuseAddress, setReusePort, setSendBufferSize, setSendTimeout, shutdown, shutdownReceive, shutdownSend, sockfd, supportsIPv4, supportsIPv6, type

## Enumerations

### TelnetCodes

TELNET_SE = 240

TELNET_NOP = 241

TELNET_DM = 242

TELNET_BRK = 243

TELNET_IP = 244

TELNET_AO = 245

TELNET_AYT = 246

TELNET_EC = 247

TELNET_EL = 248

TELNET_GA = 249

TELNET_SB = 250

TELNET_WILL = 251

TELNET_WONT = 252

TELNET_DO = 253

TELNET_DONT = 254

TELNET_IAC = 255

## Constructors

### DialogSocket

DialogSocket();

Creates an unconnected stream socket.

Before sending or receiving data, the socket must be connected with a call to connect().

### DialogSocket

explicit DialogSocket(
const SocketAddress & address
);

Creates a stream socket and connects it to the socket specified by address.

### DialogSocket

DialogSocket(
const Socket & socket
);

Creates the DialogSocket with the SocketImpl from another socket. The SocketImpl must be a StreamSocketImpl, otherwise an InvalidArgumentException will be thrown.

### DialogSocket

DialogSocket(
const DialogSocket & socket
);

Creates the DialogSocket as copy of another dialog socket.

## Destructor

### ~DialogSocket

~DialogSocket() override;

Destroys the DialogSocket.

## Member Functions

### get

int get();

Reads one character from the connection.

Returns -1 (EOF_CHAR) if no more characters are available.

### operator =

DialogSocket & operator = (
const Socket & socket
);

Assignment operator.

Releases the socket's SocketImpl and attaches the SocketImpl from the other socket and increments the reference count of the SocketImpl.

### operator =

DialogSocket & operator = (
const DialogSocket & socket
);

Assignment operator.

### peek

int peek();

Returns the character that would be returned by the next call to get(), without actually extracting the character from the buffer.

Returns -1 (EOF_CHAR) if no more characters are available.

### receiveMessage

bool receiveMessage(
std::string & message
);

Receives a single-line message, terminated by CR-LF, from the socket connection and appends it to response.

Returns true if a message has been read or false if the connection has been closed by the peer.

### receiveRawBytes

int receiveRawBytes(
void * buffer,
int length
);

Read up to length bytes from the connection and place them into buffer. If there are data bytes in the internal buffer, these bytes are returned first.

Use this member function instead of receiveBytes().

Returns the number of bytes read, which may be less than requested.

### receiveStatusMessage

int receiveStatusMessage(
std::string & message
);

Receives a single-line or multi-line response from the socket connection. The format must be according to one of the response formats specified in the FTP (RFC 959) or SMTP (RFC 2821) specifications.

The first line starts with a 3-digit status code. Following the status code is either a space character (' ' ) (in case of a single-line response) or a minus character ('-') in case of a multi-line response. The following lines can have a three-digit status code followed by a minus-sign and some text, or some arbitrary text only. The last line again begins with a three-digit status code (which must be the same as the one in the first line), followed by a space and some arbitrary text. All lines must be terminated by a CR-LF sequence.

The response contains all response lines, separated by a newline character, including the status code. The status code is returned. If the response line does not contain a status code, 0 is returned.

### sendByte

void sendByte(
unsigned char ch
);

Sends a single byte over the socket connection.

### sendMessage

void sendMessage(
const std::string & message
);

Appends a CR-LF sequence to the message and sends it over the socket connection.

### sendMessage

void sendMessage(
const std::string & message,
const std::string & arg
);

Concatenates message and arg, separated by a space, appends a CR-LF sequence, and sends the result over the socket connection.

### sendMessage

void sendMessage(
const std::string & message,
const std::string & arg1,
const std::string & arg2
);

Concatenates message and args, separated by a space, appends a CR-LF sequence, and sends the result over the socket connection.

### sendString

void sendString(
const char * str
);

Sends the given null-terminated string over the socket connection.

### sendString

void sendString(
const std::string & str
);

Sends the given string over the socket connection.

### sendTelnetCommand

void sendTelnetCommand(
unsigned char command
);

Sends a TELNET command sequence (TELNET_IAC followed by the given command) over the connection.

### sendTelnetCommand

void sendTelnetCommand(
unsigned char command,
unsigned char arg
);

Sends a TELNET command sequence (TELNET_IAC followed by the given command, followed by arg) over the connection.

### synch

void synch();

Sends a TELNET SYNCH signal over the connection.

According to RFC 854, a TELNET_DM char is sent via sendUrgent().

### allocBuffer

void allocBuffer();

### receiveLine

bool receiveLine(
std::string & line,
std::size_t lineLengthLimit = 0
);

### receiveStatusLine

int receiveStatusLine(
std::string & line,
std::size_t lineLengthLimit = 0
);

### refill

void refill();