golang net package simulation

這是一個建立於 的文章，其中的資訊可能已經有所發展或是發生改變。

Let's make some fun to simulation  Server - Client.

 

1.  socket

I implement a echo server and use telnet to simulate the socket client.

in this way,  we don't need to implement our socket client but can test our client server in a standard way.

It can support multiple telnet clients concurrently. The behavior is as bellow.

when user input "BYE",  the connect to server shuts down.

code snippet:

 1 package main 2  3 import ( 4     "bufio" 5     "fmt" 6     "io" 7     "log" 8     "net" 9     "strings"10 )11 12 func main() {13     // Listen on TCP port 2000 on all interfaces.14     l, err := net.Listen("tcp", ":2000")15     if err != nil {16         log.Fatal(err)17     }18     defer l.Close()19 20     for {21         // Wait for a connection.22         conn, err := l.Accept()23         if err != nil {24             log.Fatal(err)25         }26         fmt.Println("INFO: accept a client")27 28         // Handle the connection in a new goroutine.29         go func(c net.Conn) {30             defer c.Close()31 32             rd := bufio.NewReader(c)33             for {34                 line, _, err := rd.ReadLine()35                 if err != nil && err != io.EOF {36                     log.Fatal(err)37                 }38 39                 s := string(line)40                 fmt.Println("LOG:", s)41 42                 //since rd.ReadLine() has trimed last "\n", append here to echo43                 _, err = conn.Write([]byte("ECHO:" + s + "\r\n"))44                 if err != nil {45                     log.Fatal(err)46                 }47 48                 if strings.ToLower(s) == "bye" {49                     fmt.Println("INFO: client closed")50                     break51                 }52             }53         }(conn)54     }55 }

 

2. http.Client