tcp流量转发到不同的后端

想把流量发个多个后端，每个后端都可以收到内容，但我写的，每次都只有一个后端收到内容，随机的

package main

import (
    "flag"
    "fmt"
    "io"
    "net"
    "strings"
)

var tcp_conn []net.Conn

func main() {
    var address *string
    var dst *string
    address = flag.String("listen_address", "127.0.0.1:8080", "listen address")
    dst = flag.String("target_address", "172.16.5.9:18061,172.16.5.9:18060", "目标地址,多个地址逗号分割")
    flag.Parse()
    listener, err := net.Listen("tcp", *address)
    if err != nil {
        fmt.Println(err)
    }
    ips := strings.Split(*dst, ",")
    if len(ips) == 0 {
        fmt.Println("目标地址不能为空")
        return
    }
    for _, ip := range ips {
        conn, err := net.Dial("tcp", ip)
        if err != nil {
            fmt.Println(err)
            continue
        }
        tcp_conn = append(tcp_conn, conn)
    }
    for {
        conn, err := listener.Accept()
        if err != nil {
            continue
        }
        go handler(conn)
    }

}

func handler(conn net.Conn) {
    // defer conn.Close()
    for _, dst_conn := range tcp_conn {
        go io.Copy(dst_conn, conn)
        go io.Copy(conn, dst_conn)
    }
}

该如何改呢，哪位大佬帮忙看看