Ruby Web Server

Building a simple web server with Ruby socket. This web server is in its simplest form. Listening at port 4567, accept GET request, response with “Hello World”, reject all other request with “Forbidden”.

require 'socket'
def response(client, status, headers, body)
  client.print "HTTP/1.1 #{status}\r\n"
  headers.each do |key, value|
    client.print "#{key}: #{value}\r\n"
  end
  client.print "\r\n"
  body.each do |part|
    client.print part
  end
end
server=TCPServer.new 4567
puts "server started"
loop do
  Thread.start(server.accept) do |client|
    begin
      req=client.gets
      request_headers, request_body=client.readpartial(2048).split("\r\n\r\n",2)
      method, url=request.split(' ')
      if method=='GET'
        response(client,200,{'Content-Type'=>'text/plain'},['Hello World'])
      else
        response(client,403,{'Content-Type'=>'text/plain'},['Forbidden'])
      end
    rescue => e
      puts e
    ensure
      client.close
    end
  end
end

In its simplest form may not be the most best or efficient. Codes below are enhancement to the simplest form. Enhancements are

- Multi processes, so that slow connection does not hog up the web server.
- Ability to access the request header and query strings in a hash.
- Ability to detect URL path and process accordingly.
- Ability to get the request IP address.

require 'socket'
def str_query_strings_to_hash(str)
  hash=Hash.new
  unless str.nil?
    params=str.split('&')
    params.each do|param|
      pair=param.split('=',2)
      hash[pair[0].downcase]=pair[1]
    end
  end
  return hash
end
def str_headers_to_hash(str)
  hash=Hash.new
  lines=str.split("\r\n")
  lines.each do|line|
    pair=line.split(':')
    hash[pair[0].to_s.strip.downcase]=pair[1].to_s.strip
  end
  return hash
end
app = Proc.new do|param|
  headers=str_headers_to_hash(param['request_headers'])
  method=param["request_method"]
  path=param["path"]
  query_strings=str_query_strings_to_hash(param['query_strings'])
  ip=param["ip"]
  if method=='GET' and path == '/'
    ['200', {'Content-Type' => 'text/plain'}, ["Hello World"]]
  else
    ['403', {'Content-Type' => 'text/plain'}, ["Forbidden"]]
  end
end
def response(client, status, headers, body)
  client.print "HTTP/1.1 #{status}\r\n"
  headers.each do |key, value|
    client.print "#{key}: #{value}\r\n"
  end
  client.print "\r\n"
  body.each do |part|
    client.print part
  end
end
server=TCPServer.new 4567
puts "server started"
loop do
  Thread.start(server.accept) do |client|
    begin
      request=client.gets
      request_headers, request_body=client.readpartial(2048).split("\r\n\r\n",2)
      method, remainder=request.split(' ',2)
      remainder=remainder.split(' ')
      remainder.pop
      url=remainder.join(' ')
      path, query_strings=url.split('?',2)
      status, headers,body=app.call({
        'request_headers'=>request_headers,
        'request_method'=>method,
        'path'=>path,
        'query_strings'=>query_strings,
        'ip'=>client.peeraddr[3]
      })
      response(client, status, headers, body)
    rescue => e
      puts e
    ensure
      client.close
    end
  end
end

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