wohavg
Last Updated: March 20, 2017
·
42.49K
· donutdan4114
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Creating a simple TCP server in Go

package main

import (
    "fmt"
    "net"
    "os"
)

const (
    CONN_HOST = "localhost"
    CONN_PORT = "3333"
    CONN_TYPE = "tcp"
)

func main() {
    // Listen for incoming connections.
    l, err := net.Listen(CONN_TYPE, CONN_HOST+":"+CONN_PORT)
    if err != nil {
        fmt.Println("Error listening:", err.Error())
        os.Exit(1)
    }
    // Close the listener when the application closes.
    defer l.Close()
    fmt.Println("Listening on " + CONN_HOST + ":" + CONN_PORT)
    for {
        // Listen for an incoming connection.
        conn, err := l.Accept()
        if err != nil {
            fmt.Println("Error accepting: ", err.Error())
            os.Exit(1)
        }
        // Handle connections in a new goroutine.
        go handleRequest(conn)
    }
}

// Handles incoming requests.
func handleRequest(conn net.Conn) {
  // Make a buffer to hold incoming data.
  buf := make([]byte, 1024)
  // Read the incoming connection into the buffer.
  reqLen, err := conn.Read(buf)
  if err != nil {
    fmt.Println("Error reading:", err.Error())
  }
  // Send a response back to person contacting us.
  conn.Write([]byte("Message received."))
  // Close the connection when you're done with it.
  conn.Close()
}

If you build this and run it, you'll have a simple TCP server running on port 3333.
To test your server, send some raw data to that port:

echo -n "test out the server" | nc localhost 3333

You should get a response:

"Message received."
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15381
F3a6662b3cd161c3c2f13604965ed0f2

I just wrote an article that describes how to "dockerize" a Go app very similar on the one you described here. Obviously I mentioned this post. Let me know if you like it: http://loige.com/simple-echo-server-written-in-go-dockerized

over 1 year ago ·
23339
None

Just a little bug:

$ go run tcp_server.go

command-line-arguments

.\tcp_server.go:42: reqLen declared and not used

Regards!

over 1 year ago ·
25023
None

Change unused variables with underscore ( _ ). Compiler won't complain.

over 1 year ago ·