transfercmd

# File lib/net/ftp.rb, line 402
    def transfercmd(cmd, rest_offset = nil) # :nodoc:
      if @passive
        host, port = makepasv
        conn = open_socket(host, port)
        if @resume and rest_offset
          resp = sendcmd("REST " + rest_offset.to_s)
          if resp[0] != 33
            raise FTPReplyError, resp
          end
        end
        resp = sendcmd(cmd)
        # skip 2XX for some ftp servers
        resp = getresp if resp[0] == 22
        if resp[0] != 11
          raise FTPReplyError, resp
        end
      else
        sock = makeport
        begin
          sendport(sock.addr[3], sock.addr[1])
          if @resume and rest_offset
            resp = sendcmd("REST " + rest_offset.to_s)
            if resp[0] != 33
              raise FTPReplyError, resp
            end
          end
          resp = sendcmd(cmd)
          # skip 2XX for some ftp servers
          resp = getresp if resp[0] == 22
          if resp[0] != 11
            raise FTPReplyError, resp
          end
          conn = BufferedSocket.new(sock.accept)
          conn.read_timeout = @read_timeout
          sock.shutdown(Socket::SHUT_WR) rescue nil
          sock.read rescue nil
        ensure
          sock.close
        end
      end
      return conn
    end