anchor.diff:             (header-length (* (ldb (byte 4 12) flags-and-data-offset) 4))
              (data-length (- end (+ start header-length))))
         (case (tcp-connection-state connection)
  +        (:listen
  +         ;; Remote has start new connection.
  +         ;; Not much to do here, just waiting for the application to accept or decline new connection.
  +         )
           (:syn-sent
            (cond ((and (logtest flags +tcp4-flag-ack+)
                        (logtest flags +tcp4-flag-syn+)
  
positive.code: 
  (defvar *tcp-connections* nil)
  (defvar *tcp-connection-lock* (mezzano.supervisor:make-mutex "TCP connection list"))
  (defvar *allocated-tcp-ports* nil)
  
  (defvar *server-alist* '())
  
  (defclass tcp-connection ()
    ((%state :accessor tcp-connection-%state :initarg :%state)
  
negative.code:   `(mezzano.supervisor:with-mutex ((tcp-connection-lock ,connection))
       ,@body))
  
  (defun get-tcp-listener (local-ip local-port)
    (mezzano.supervisor:with-mutex (*tcp-listener-lock*)
      (dolist (listener *tcp-listeners*)
        (when (and (or (mezzano.network.ip:address-equal
                        (tcp-listener-local-ip listener) local-ip)
                       (mezzano.network.ip:address-equal
                        (mezzano.network.ip:make-ipv4-address "0.0.0.0")
                        (tcp-listener-local-ip listener)))
                   (eql (tcp-listener-local-port listener) local-port))
          (return listener)))))
  
  (defun get-tcp-connection (remote-ip remote-port local-ip local-port)
    (mezzano.supervisor:with-mutex (*tcp-connection-lock*)
      (dolist (connection *tcp-connections*)
  