Simple Client Server using tidwall/sds

clientserver.go

package main

import (
	"errors"
	"log"
	"net"
	"os"
	"time"

	"github.com/tidwall/sds"
)

func main() {
	if len(os.Args) > 1 && os.Args[1] == "server" {
		log.Printf("server at :9999")
		log.Fatal(server(":9999"))
	} else {
		log.Printf("client at :9999")
		log.Fatal(client(":9999"))
	}
}

func server(addr string) error {
	ln, err := net.Listen("tcp", addr)
	if err != nil {
		return err
	}
	for {
		c, err := ln.Accept()
		if err != nil {
			if errors.Is(err, net.ErrClosed) {
				return nil
			}
			log.Printf("%s\n", err.Error())
			continue
		}
		log.Printf("client connected from %s", c.RemoteAddr())
		go func(c net.Conn) {
			defer func() {
				c.Close()
				log.Printf("client disconnected from %s", c.RemoteAddr())
			}()
			r := sds.NewReader(c)
			w := sds.NewWriter(c)
			for {
				msg, err := r.ReadBytes()
				if err != nil {
					return
				}
				// TODO: something rad with message, but in this case we'll
				// just echo it back to the client.
				println(string(msg))
				if err := w.WriteBytes(msg); err != nil {
					return
				}
				if err := w.Flush(); err != nil {
					return
				}
			}
		}(c)
	}
}

func client(addr string) error {
	c, err := net.Dial("tcp", addr)
	if err != nil {
		return err
	}
	defer c.Close()
	r := sds.NewReader(c)
	w := sds.NewWriter(c)
	for {
		if err := w.WriteBytes([]byte(time.Now().String())); err != nil {
			return err
		}
		if err := w.Flush(); err != nil {
			return err
		}
		msg, err := r.ReadBytes()
		if err != nil {
			return err
		}
		println(string(msg))
		time.Sleep(time.Second)
	}
}

In terminal 1:

go run clientserver.go server

In terminal 2:

go run clientserver.go client