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 or perhaps ::1). Logging of connection information to standard output is recommended.

The implementation must be able to handle simultaneous connections from multiple clients. A multi-threaded or multi-process solution may be used. Each connection must be able to echo more than a single line.

The implementation must not stop responding to other clients if one client sends a partial line or stops reading responses.

include unix/socket.fs
 
128 constant size
 
: (echo) ( sock buf -- sock buf )
  begin
    cr ." waiting..."
    2dup 2dup size read-socket nip
    dup 0>
  while
    ."  got: " 2dup type
    rot write-socket
  repeat
  drop drop drop ;
 
create buf size allot
 
: echo-server ( port -- )
  cr ." Listening on " dup .
  create-server
  dup 4 listen
  begin
    dup accept-socket
    cr ." Connection!"
    buf ['] (echo) catch
    cr ." Disconnected (" . ." )"
    drop close-socket
  again ;
 
12321 echo-server