golang tcp chat anonymous multi-participant

package main

import (
	"bufio"
	"fmt"
	"log"
	"net"
	"sync"
)

type Conns struct {
	mu    sync.Mutex
	nodes map[string]net.Conn
}

func (c *Conns) AddNode(addr string, conn net.Conn) {

	if c.nodes == nil {
		c.nodes = make(map[string]net.Conn)
	}

	c.mu.Lock()
	defer c.mu.Unlock()
	c.nodes[addr] = conn
}

func (c *Conns) DelNode(addr string) {
	c.mu.Lock()
	defer c.mu.Unlock()
	if _, ok := c.nodes[addr]; ok {
		delete(c.nodes, addr)
	}
}

func (c *Conns) Map(function func(net.Conn)) {
	// c.mu.Lock()
	// defer c.mu.Unlock()
	for _, conn := range c.nodes {
		function(conn)
	}
}

func main() {
	l, err := net.Listen("tcp", ":9898")
	conns := Conns{}
	if err != nil {
		log.Fatal(err)
	}
	for {
		conn, err := l.Accept()
		if err != nil {
			log.Fatal(err)
		}
		conns.AddNode(conn.RemoteAddr().String(), conn)
		conns.Map(func(rCon net.Conn) {
			fmt.Fprintf(rCon, "%s joined the chat \n", conn.RemoteAddr().String())
		})
		go func() {
			defer conns.DelNode(conn.RemoteAddr().String())
			scanr := bufio.NewScanner(conn)
			for scanr.Scan() {
				conns.Map(func(rConn net.Conn) {
					msgBytes := scanr.Bytes()
					if string(msgBytes) == "/exit" {
						conn.Close()
						return
					}
					if rConn.RemoteAddr().String() != conn.RemoteAddr().String() {
						rConn.Write(msgBytes)
						rConn.Write([]byte("\n"))
					}
				})
			}
		}()
	}
}