Echo server

Echo server
You are encouraged to solve this task according to the task description, using any language you may know.

Create a network service that sits on TCP port 12321, which accepts connections on that port, and which echoes complete lines (using a carriage-return/line-feed sequence as line separator) back to clients. No error handling is required. For the purposes of testing, it is only necessary to support connections from localhost (127.0.0.1). Logging of connection information to standard output is recommended.

Tcl

<lang tcl># How to handle an incoming new connection proc acceptEcho {chan host port} {

   puts "opened connection from $host:$port"
   fconfigure $chan -blocking 0 -buffering line -translation crlf
   fileevent $chan readable [list echo $chan $host $port]

}

1. How to handle an incoming message on a connection

proc echo {chan host port} {

   if {[gets $chan line] >= 0} {
       puts $chan $line
   } elseif {[eof $chan]} {
       close $chan
       puts "closed connection from $host:$port"
   }
   # Other conditions causing a short read need no action

}

1. Make the server socket and wait for connections

socket -server acceptEcho -myaddr localhost 12321 vwait forever</lang>