Implementation of Go language Telnet echo server

package main

import (
  "fmt"
  "net"
  "bufio"
  "strings"
  "os"
)

func main() {

  // Create a channel for ending the program  exitChan := make(chan int)

  // Run the server concurrently  go server("127.0.0.1:7001", exitChan)

  // Channel blocking, waiting for the return value to be received  code := <-exitChan

  // Mark the program's return value and exit  (code)
}

// Service logic, incoming address and exit channelfunc server(address string, exitChan chan int) {

  // Listen according to the given address  l, err := ("tcp", address)

  // If an error occurs when listening, print the error and exit  if err != nil {
   (())
   exitChan <- 1
  }

  // Print the listening address, indicating that the listening is successful  ("listen: " + address)

  // Delay shutdown of the listener  defer ()

  // Listen to loop  for {

   // Accept is blocking when the new connection does not arrive   conn, err := ()

   // Any listening error occurs, print the error and exit the server   if err != nil {
     (())
     continue
   }

   // Open the session according to the connection, this process needs to be executed in parallel   go handleSession(conn, exitChan)
  }
}

// Connected session logicfunc handleSession(conn , exitChan chan int) {

  ("Session started:")

  // Create a network connection data reader  reader := (conn)

  // Receive data loop  for {

   // Read the string until it hits Enter and return   str, err := ('\n')

   // The data is read correctly   if err == nil {

     // Remove the carriage return at the end of the string     str = (str)

     // Process Telnet commands     if !processTelnetCommand(str, exitChan) {
      ()
      break
     }

     // Echo logic, what data should be sent, return as it is     ([]byte(str + "\r\n"))

   } else {
     // An error occurred     ("Session closed")
     ()
     break
   }
  }

}

//Command processingfunc processTelnetCommand(str string, exitChan chan int) bool {

  // @close command indicates the end of this session  if (str, "@close") {

   ("Session closed")

   // Tell the outside to disconnect   return false

   // @shutdown directive indicates the service process being terminated  } else if (str, "@shutdown") {

   ("Server shutdown")

   // Write 0 into the channel, blocking and waiting for the receiver to process   exitChan <- 0

   // Tell the outside to disconnect   return false
  }

  // Print the input string  (str)

  return true

}