Ruby Socket Programming

Socket programming is a method of communication between two computers using a network protocol, typically TCP/IP. In Ruby, the socket standard library provides the capabilities to create both server and client sockets for communication.

Here's a basic tutorial on socket programming in Ruby.

1. Basic TCP Server

require 'socket'

server = TCPServer.new(8080)

loop do
  socket = server.accept
  request = socket.gets
  STDERR.puts request

  response = "Hello World!\n"

  socket.print "HTTP/1.1 200 OK\r\n" +
               "Content-Type: text/plain\r\n" +
               "Content-Length: #{response.bytesize}\r\n" +
               "Connection: close\r\n"

  socket.print "\r\n"

  socket.print response
  socket.close
end

In this example, we're creating a basic HTTP server that listens on port 8080 and responds with "Hello World!" to any request.

2. Basic TCP Client

require 'socket'

socket = TCPSocket.new('localhost', 8080)
socket.print "GET / HTTP/1.1\r\nHost: localhost\r\n\r\n"
response = socket.read

headers, body = response.split("\r\n\r\n", 2)

print body

This client connects to the server we created above, sends a basic HTTP GET request, and then prints out the response body.

Some Notes

When we call TCPServer.new(8080), it binds a new TCP server to port 8080. The server will listen on this port for incoming connections.
The server.accept call is blocking, meaning it will wait until a client connects to the server. When a client connects, it returns a TCPSocket object that we can read from and write to.
The socket.gets call reads one line from the socket. In this case, it's reading the first line of the HTTP request.
We then create an HTTP response and write it to the socket with socket.print.
Finally, we close the socket. If we didn't do this, the client would continue waiting for a response.

This is a very basic introduction to socket programming in Ruby. There's much more you can do, including handling multiple clients at the same time, using non-blocking I/O, and more. However, this should give you a good starting point.

Creating sockets in Ruby: Use the Socket class to create sockets.

require 'socket'

server_socket = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM, 0)

TCP socket programming in Ruby: Create a TCP server and client for communication.

# TCP Server
server = TCPServer.new(2000)

# TCP Client
client = TCPSocket.new('localhost', 2000)

UDP socket programming in Ruby: Use UDP for connectionless communication.

# UDP Server
server = UDPSocket.new

# UDP Client
client = UDPSocket.new

Socket communication in Ruby: Send and receive data over sockets.

# Server
client_socket = server.accept
data = client_socket.recv(1024)

# Client
client.send('Hello, server!', 0, server_addr, server_port)

Ruby socket server example: Implement a basic TCP server.

require 'socket'

server = TCPServer.new(2000)

loop do
  client = server.accept
  client.puts 'Hello, client!'
  client.close
end

Ruby socket client example: Implement a basic TCP client.

require 'socket'

client = TCPSocket.new('localhost', 2000)
puts client.gets
client.close

Handling multiple connections in Ruby sockets: Use threads or event-driven frameworks to handle multiple connections.

# Using threads
loop do
  Thread.start(server.accept) do |client|
    client.puts 'Hello, client!'
    client.close
  end
end

Socket options and configurations in Ruby: Configure socket options for specific behaviors.
```
server.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, true)
```

Securing socket connections in Ruby: Use SSL/TLS for secure socket communication.

require 'openssl'

context = OpenSSL::SSL::SSLContext.new
context.cert = OpenSSL::X509::Certificate.new(File.open('server.crt'))
context.key = OpenSSL::PKey::RSA.new(File.open('server.key'))
ssl_server = OpenSSL::SSL::SSLServer.new(server, context)

Non-blocking socket programming in Ruby: Implement non-blocking I/O with IO.select or event-driven frameworks.
```
# Using IO.select
read, _, _ = IO.select([server])
client = read[0].accept
```

Ruby socket timeouts and retries: Set timeouts for socket operations and implement retry mechanisms.

require 'timeout'

begin
  Timeout.timeout(5) do
    client_socket.recv(1024)
  end
rescue Timeout::Error
  puts 'Operation timed out'
end

Broadcasting with sockets in Ruby: Broadcast data to multiple recipients.

# UDP Broadcast Server
server.setsockopt(Socket::SOL_SOCKET, Socket::SO_BROADCAST, true)

# UDP Broadcast Client
client.send('Broadcast message', 0, '255.255.255.255', server_port)

Socket programming for inter-process communication in Ruby: Use UNIX domain sockets or other IPC mechanisms for communication between processes.
```
# UNIX Domain Socket
server = UNIXServer.new('/tmp/socket.sock')
client = UNIXSocket.new('/tmp/socket.sock')
```