package main

import (
	"fmt"
	"net"
)

func main() {
	ln, err := net.Listen("tcp4", "127.0.0.1:0")
	if err != nil {
		fmt.Printf("Listen failed: %v\n", err)
		return
	}
	defer ln.Close()
	ch := make(chan error, 1)
	go func() {
		c, err := ln.Accept()
		if err != nil {
			ch <- fmt.Errorf("Accept failed: %v\n", err)
			return
		}
		defer c.Close()
		ch <- nil
	}()

	laddr, err := net.ResolveTCPAddr("tcp4", "127.0.0.1:0")
	if err != nil {
		fmt.Printf("ResolveTCPAddr failed: %v\n", err)
		return
	}
	d := &net.Dialer{LocalAddr: laddr}
	c, err := d.Dial("tcp4", ln.Addr().String())
	if err != nil {
		fmt.Printf("Dial failed: %v\n", err)
		return
	}
	defer c.Close()
	c.Read(make([]byte, 1))
	err = <-ch
	if err != nil {
		fmt.Println(err)
	}
}