Dart SocketOption
last modified April 4, 2025
The SocketOption class in Dart provides a way to configure socket
options for network communication. It's part of Dart's dart:io
library and works with both TCP and UDP sockets.
Socket options control various low-level behaviors of network sockets, such as timeout settings, buffer sizes, and protocol-specific configurations. They're essential for fine-tuning network performance.
Basic Definition
SocketOption represents a socket-level configuration option that
can be applied to sockets. Each option has a level and name that identify it.
The class provides predefined constants for common options and allows creating custom options. Options are applied using socket's setOption method.
Setting Socket Timeout
This example demonstrates setting a receive timeout on a socket.
import 'dart:io';
void main() async {
var socket = await Socket.connect('example.com', 80);
// Set receive timeout to 5 seconds
socket.setOption(SocketOption.tcpNoDelay, true);
socket.setOption(SocketOption.receiveTimeout, Duration(seconds: 5));
print('Socket options configured');
await socket.close();
}
We create a TCP socket and set two options: TCP_NODELAY and receive timeout. The timeout will cause the socket to throw an exception if no data is received.
$ dart main.dart Socket options configured
Enabling Broadcast on UDP Socket
This example shows how to enable broadcast on a UDP socket.
import 'dart:io';
void main() async {
var socket = await RawDatagramSocket.bind(InternetAddress.anyIPv4, 0);
// Enable broadcast
socket.setOption(SocketOption.broadcast, true);
print('Broadcast enabled on UDP socket');
socket.close();
}
We create a UDP socket and enable broadcast capability. This allows sending packets to the broadcast address of the local network.
$ dart main.dart Broadcast enabled on UDP socket
Configuring Keep-Alive
This example demonstrates enabling TCP keep-alive on a socket.
import 'dart:io';
void main() async {
var socket = await Socket.connect('example.com', 80);
// Enable TCP keep-alive
socket.setOption(SocketOption.keepAlive, true);
print('Keep-alive enabled');
await socket.close();
}
TCP keep-alive periodically checks if the connection is still alive. This helps detect broken connections when no data is being transmitted.
$ dart main.dart Keep-alive enabled
Setting Custom Socket Option
This example shows how to set a custom socket option not predefined in Dart.
import 'dart:io';
void main() async {
var socket = await Socket.connect('example.com', 80);
// Create custom socket option (IP_TOS on Linux)
var customOption = SocketOption(SocketOption.levelIP, 1, 0x10);
socket.setOption(customOption, true);
print('Custom socket option set');
await socket.close();
}
We create a custom socket option by specifying level, option name, and value. This example sets the IP Type of Service (TOS) field for quality of service.
$ dart main.dart Custom socket option set
Configuring Socket Buffer Sizes
This example demonstrates setting socket send and receive buffer sizes.
import 'dart:io';
void main() async {
var socket = await Socket.connect('example.com', 80);
// Set buffer sizes
socket.setOption(SocketOption.sendBufferSize, 8192);
socket.setOption(SocketOption.receiveBufferSize, 16384);
print('Socket buffer sizes configured');
await socket.close();
}
We configure the socket's send and receive buffer sizes. Larger buffers can improve performance for high-bandwidth connections but use more memory.
$ dart main.dart Socket buffer sizes configured
Best Practices
- Set early: Configure options immediately after socket creation
- Check support: Some options may not be available on all platforms
- Document: Clearly document custom socket options
- Test: Verify option effects in your specific environment
Source
Dart SocketOption Documentation
This tutorial covered Dart's SocketOption class with practical examples showing common socket configurations and custom options for network programming.
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