I) usage description
--------------------

This feature only works in active mode and if you have both "dctc link" 
and "direct download" options enabled.

The goal of the UNODE system is the sharing of UADDR client database and
the relaying of search queries between clients not located on the same
computer.

Using it, if you have DCTC clients running on more than one computer or
if you want to share your UADDR database with friends, you just have to
put the address (hostname or IP) in the UNODE list and they have to put
your address in their UNODE list. 

After these operations, each search you made is sent as usual to the hubs
you are connected to but also to the hubs where remote clients are
connected to.

If you try to download from someone not present on all your contacted hubs
and you also do not have its address, your UNODE will contact all others
UNODE it knows and ask them if they have this user address.



II) Technical description:
--------------------------

* The local unix socket understand 2 commands:
$Search (same syntax as DC)|
    works like the normal search
$UADDR? nick|
    ask to other node if they know "nick".

When these commands arrive, they are relayed to other UNODEs.

* The local internet socket understand 3 commands:
$Search (same syntax as DC)|
    the search query is send to local client using "dctc link".
$UADDR? nick|
    if the user is unknown, nothing happens, else, the following
    result is sent: "$UADDR |host:ip|nick|" to the UNODE requesting it.
$UADDR |host:ip|nick|
    the host:ip and the nick is inserted into the local UADDR base.


NOTE: there is no \n at the end of the line */
NOTE2: for security reason, packets coming from untrusted hosts are discarded.

    
