Go chat server

README.md

Installation

go run server.go

Usage

telnet localhost 9000 #A
# separate terminal
telnet localhost 9000 #B

Then chat between the users:

#A
SexyT
#B
Josh
Yo
#A
hi

Which should result in the following output:

#A should see:
The room is empty.
Username:
You've logged on as SexyT.
Josh has joined.
Josh: Yo
SexyT: hi

#B should see:
Username:
Participants: SexyT
You've logged on as Josh.
Josh: Yo
SexyT: hi

server.go

package main

import (
	"fmt"
	"net"
	"strings"
	"sync"
)

type message struct {
	user []byte
	body []byte
}

type client struct {
	user   []byte
	client net.Conn
	close  chan struct{}
}
type room struct {
	m       chan message
	clients []*client
	clientsMutex sync.Mutex // RWMutex might make more sense. Maybe.
}

func (c *client) sendMsg(b []byte) {
	fmt.Fprintf(c.client, "%s %s\n", c.user, b)
}

func (c *client) hear(msg message) {
	fmt.Fprintf(c.client, "%s:  %s", msg.user, msg.body)
}

func (r *room) handleConnection(conn net.Conn) {

	reqLen, err := fmt.Fprintf(conn, "Username: ")
	if err != nil {
		fmt.Println(err)
	}

	buf := make([]byte, 1024)
	reqLen, err = conn.Read(buf)
	user := client{
		user:   ([]byte)(strings.TrimSpace(string(buf[0:reqLen]))),
		client: conn,
	}

	r.addClient(user)
	fmt.Fprintf(conn, "You've logged on as %s\n", user.user)
	for {
		reqLen, err := conn.Read(buf)
		if err != nil {
			fmt.Println(err)
		}
		if strings.TrimSpace(string(buf[0:reqLen])) == "/quit" {

			conn.Close()
			return // can't write to this connection any more
		}
		m := message{
			user: user.user,
			body: buf[0:(reqLen - 1)],
		}
		r.m <- m
	}
}

func (r *room) addClient(c client) {
	//r.clientsMutex.Lock()
	//defer r.clientsMutex.Unlock()
	for i := range r.clients {
		fmt.Fprintf(r.clients[i].client, "%s has joined \n", c.user)
	}
	fmt.Fprintf(c.client, "Participants: %#v.\n", r.clients)
	r.clients = append(r.clients, &c)
}

func (r *room) broadcastMsg(m message) {
	for i := range r.clients {
		r.clients[i].hear(m)
	}
}

func (r *room) broadcast() {
	for {
		select {
		case i := <-r.m:
			r.broadcastMsg(i)
		}
	}
}

func (r *room) listener() {
	ln, err := net.Listen("tcp", ":9000")
	if err != nil {
		fmt.Println(err)
	}
	go r.broadcast()
	for {
		conn, err := ln.Accept()
		if err != nil {
			fmt.Println(err)
			continue
		}
		go r.handleConnection(conn)
	}

}

func main() {
	oneRoomToRuleThemAll := room{
		m: make(chan message),
	}
	oneRoomToRuleThemAll.listener()
}

Without this https://gist.github.com/tsnow/11385848#file-server-go-L52-L55 return I get the following panic:

bash-3.2$ go run server.go
use of closed network connection
panic: runtime error: slice bounds out of range

goroutine 5 [running]:
main.(*room).handleConnection(0xc200082040, 0xc200087060, 0xc2000000b8)
    /Users/tsnow/go/src/chat/server.go:59 +0x582
created by main.(*room).listener
    /Users/tsnow/go/src/chat/server.go:101 +0x1f6

goroutine 1 [IO wait]:
net.runtime_pollWait(0x28bf00, 0x72, 0x0)
    /usr/local/go/src/pkg/runtime/znetpoll_darwin_amd64.c:118 +0x82
net.(*pollDesc).WaitRead(0xc200083080, 0x23, 0xc20007b2d0)
    /usr/local/go/src/pkg/net/fd_poll_runtime.go:75 +0x31
net.(*netFD).accept(0xc200083000, 0x12ecd0, 0x0, 0xc20007b2d0, 0x23, ...)
    /usr/local/go/src/pkg/net/fd_unix.go:385 +0x2c1
net.(*TCPListener).AcceptTCP(0xc200000090, 0x2f56, 0x27ae90, 0x2f56)
    /usr/local/go/src/pkg/net/tcpsock_posix.go:229 +0x45
net.(*TCPListener).Accept(0xc200000090, 0xc200087060, 0xc2000000e8, 0x0, 0x0, ...)
    /usr/local/go/src/pkg/net/tcpsock_posix.go:239 +0x25
main.(*room).listener(0xc200082040)
    /Users/tsnow/go/src/chat/server.go:96 +0x12f
main.main()
    /Users/tsnow/go/src/chat/server.go:110 +0x8b

goroutine 2 [syscall]:

goroutine 4 [runnable]:
main.(*room).broadcast(0xc200082040)
    /Users/tsnow/go/src/chat/server.go:83 +0x4b
created by main.(*room).listener
    /Users/tsnow/go/src/chat/server.go:94 +0x119

goroutine 6 [IO wait]:
net.runtime_pollWait(0x28bdc0, 0x72, 0x0)
    /usr/local/go/src/pkg/runtime/znetpoll_darwin_amd64.c:118 +0x82
net.(*pollDesc).WaitRead(0xc2000831a0, 0x23, 0xc20007b2d0)
    /usr/local/go/src/pkg/net/fd_poll_runtime.go:75 +0x31
net.(*netFD).Read(0xc200083120, 0xc200052800, 0x400, 0x400, 0x0, ...)
    /usr/local/go/src/pkg/net/fd_unix.go:195 +0x2b3
net.(*conn).Read(0xc2000000e8, 0xc200052800, 0x400, 0x400, 0x29bea8, ...)
    /usr/local/go/src/pkg/net/net.go:123 +0xc3
main.(*room).handleConnection(0xc200082040, 0xc200087060, 0xc2000000e8)
    /Users/tsnow/go/src/chat/server.go:48 +0x3c3
created by main.(*room).listener
    /Users/tsnow/go/src/chat/server.go:101 +0x1f6
exit status 2

https://gist.github.com/anachronistic/4046c54ce1c46e2f0ddd