Create a TCP and UDP Client and Server using Go Proposed Changes

Link: https://linode.com/docs/development/go/developing-udp-and-tcp-clients-and-servers-in-go/

Issue

The example programs create and discard bufio.Readers in inner loops. Any data buffered in the bufio.Reader is also discarded. The discarded data may not be an issue in your tests cases, but people are copying your code to their own applications where things break.

This error is common in network programming questions on StackOverflow. I suspect that many of the questioners are getting their code from this page.

Suggested Fix

Change code like this:

   for {
            reader := bufio.NewReader(os.Stdin)
            fmt.Print(">> ")
            text, _ := reader.ReadString('\n')
            fmt.Fprintf(c, text+"\n")

            message, _ := bufio.NewReader(c).ReadString('\n')
            fmt.Print("->: " + message)
            if strings.TrimSpace(string(text)) == "STOP" {
                    fmt.Println("TCP client exiting...")
                    return
            }
    }

To

   inReader := bufio.NewReader(os.Stdin)
   cReader := bufio.NewReader(c)
   for {
            fmt.Print(">> ")
            text, _ := inReader.ReadString('\n')
            fmt.Fprintf(c, text+"\n")

            message, _ := cReader.ReadString('\n')
            fmt.Print("->: " + message)
            if strings.TrimSpace(string(text)) == "STOP" {
                    fmt.Println("TCP client exiting...")
                    return
            }
    }

All uses of bufio.NewReader in the example programs have this problem. Fix all of them.

Hall of Shame (SO questions that follow the bad advice in the Linode article):

• 2020-07-31
• 2020-08-05
• 2020-08-10
• to be continued

Start with the linked Go TCP and UDP clients and servers article and inspect every example using bufio.NewReader. Keep readers reused across inner loops as shown in the issue, then verify that all example programs no longer recreate readers inside those loops.