A basic socket server in Ruby
My first bit of socket programming is a Ruby server that reads lines from the socket, and prints them. Not useful on its own, but a stepping stone to more exciting things!
I’m working on a new project that involves sockets, and I decided to try writing a basic socket server in Ruby. Here’s the code I wrote:
require 'socket'
class SocketServer
# Opens a server listening to `port` and returns a new
# `TCPServer` object.
#
# SocketServer.open(port) do |server|
# loop do
# client = server.accept
# … do stuff with client connection
# end
# end
#
# The server will automatically be shut down when the block completes.
def self.open(port)
server = TCPServer.new(port)
begin
yield(server)
rescue Interrupt
puts "\nShutting down server..."
ensure
server.close
puts "Server shut down"
end
end
# Manages a client connection on a socket.
#
# client = server.accept
#
# SocketServer.handle_client(client) do |connection|
# while line = connection.gets
# puts "Received #{line}
# … do other stuff with connection
# end
# end
#
# The connection will automatically be closed and cleaned up
# when the block completes.
def self.handle_client(client)
puts "New client connected from: #{client.remote_address.ip_address}"
begin
yield(client)
rescue Errno::ECONNRESET
puts "Client disconnected unexpectedly"
ensure
client.close
puts "Client disconnected"
end
end
end
SocketServer.open(port = 3000) do |server|
loop do
client = server.accept
SocketServer.handle_client(client) do |connection|
while line = connection.gets
line.chomp!
puts "Received: #{line}"
connection.puts "Received: #{line}"
end
end
end
end
Run it as:
$ ruby server.rb
You can send lines to the server with nc:
$ echo 'Hello world!' | nc localhost 3000
The server will print the messages sent to the socket, for example:
New client connected from: ::1
Received: Hello world!
Client disconnected
As well as my first time doing socket programming, this is the first time I’ve used Ruby’s begin … rescue … ensure blocks, which feel analogous to context managers in Python. Here’s a Stack Overflow answer by Jörg W Mittag which helped me understand what’s going on here.