A simple, incomplete, peer-to-peer chat server in Go written at Go Toronto

main.go

package main

import (
  "net"
	"strings"
	"bufio"
	"fmt"
)

const (
	MsgSize = 1024
	MaxPeers = 1024
)

type OID string;
type MID string;

type Message struct {
	oid OID
	mid MID
	msg string
}

type Peer struct {
	id int
	cxn net.Conn
	active bool
}

func (p *Peer) Close() {
	p.active = false
	println("Peer going away:", p.id)
}

type Server struct {
	peers []Peer
	seenMIDs map[MID]bool
}

func (s *Server) Handle(peerCxn net.Conn) {
	peer := Peer{len(s.peers), peerCxn, true}
	println("Peer connected:", peer.id)
	defer peer.Close()
	s.peers = append(s.peers, peer)
	reader := bufio.NewReader(peerCxn)
	for {
		line, err := reader.ReadString('\n')
		if err != nil {
			println("Read error from peer:", err.Error())
			return
		}
		line = line[0:len(line) - 1]
		println("got line:", line)
		bits := strings.SplitN(line, " ", 3)
		if len(bits) != 3 {
			fmt.Printf("Error: invalid line: %v\n", bits)
			continue
		}
		msg := Message{OID(bits[0]), MID(bits[1]), bits[2]}
		s.SendMessage(msg)
	}
}

func (s *Server) SendMessage(m Message) {
	if s.seenMIDs[m.mid] {
		return
	}
	s.seenMIDs[m.mid] = true
	println("Got message:", m.msg)
	toWrite := []byte(string(m.oid) + " " + string(m.mid) + " " + m.msg + "\n")
	for _, peer := range s.peers {
		if !peer.active {
			continue
		}
		_, err := peer.cxn.Write(toWrite)
		if err != nil {
			println("Error writing to peer:", err.Error());
			peer.Close()
		}
	}
}

func main() {
	svr := Server{make([]Peer, 0, MaxPeers), make(map[MID]bool)}
	ln, err := net.Listen("tcp", ":6060")
	if err != nil {
		println("Listen error:", err.Error())
		return
	}
	for {
		cxn, err := ln.Accept()
		if err != nil {
			println("Accept error:", err.Error())
			continue
		}
		go svr.Handle(cxn)
	}
}