Performance-oriented silly text-based protocol server in go.

sillyproto.go

package main

import (
	"bufio"
	"flag"
	"fmt"
	"io"
	"log"
	"net"
	"net/textproto"
	"runtime"
)

// Flags used to modify default behavior.
var (
	address  = flag.String("a", "0.0.0.0", "the IP address to listen on.")
	port     = flag.Int("p", 31337, "the port to listen on.")
	maxprocs = flag.Int("n", 1, "the number of CPUs to use simultaneously.")
)

// The main function listens for connections and dispatches them to handleClient via a goroutine.
func main() {
	// Parse flags and set GOMAXPROCS.
	flag.Parse()
	runtime.GOMAXPROCS(*maxprocs)

	// Create a listener on the specified address:port.
	listener, err := net.Listen("tcp", fmt.Sprintf("%s:%d", *address, *port))
	if err != nil {
		log.Fatal(err)
	}

	log.Printf("Serving silly protocols on %s:%d", *address, *port)

	// Dispatch each incoming request.
	for {
		conn, err := listener.Accept()
		defer conn.Close()
		if err != nil {
			log.Println(err)
		}
		go handleClient(conn, conn)
	}
}

// Handle a connection, respond as needed, return when the connection closes.
func handleClient(in io.Reader, out io.Writer) {
	// Set up readers and writers.
	reader := bufio.NewReader(in)
	writer := bufio.NewWriter(out)
	textreader := textproto.NewReader(reader)
	textwriter := textproto.NewWriter(writer)

	for {
		// Handle a line.
		line, err := textreader.ReadLine()

		// Handle possible errors.
		switch err {
		default:
			// Log the error.
			log.Println(err)
		case nil:
			// Do nothing.
		case io.EOF:
			// Connection closed on the other end so we return.
			return
		}

		log.Println(line)

		// Handle the incoming line based on several silly text protocol requests and responses.
		// If we don't understand the request, the proper response is DUNNO\r\n
		switch line {
		default:
			textwriter.PrintfLine("DUNNO")
		case "ORLY":
			textwriter.PrintfLine("YA RLY")
		case "HERP":
			textwriter.PrintfLine("DERP")
		case "NOWAI":
			textwriter.PrintfLine("YESWAI")
		case "OHAI":
			textwriter.PrintfLine("OHAI")
		case "NOM":
			textwriter.PrintfLine("NOM NOM NOM")
		case "OMG":
			textwriter.PrintfLine("WTF")
		case "WTF":
			textwriter.PrintfLine("BBQ")
		case "OMGWTFBBQ":
			textwriter.PrintfLine("LOLLERSKATES")
		}
	}
	return
}