[tor-dev] How Exit node decide which relay dedicated for particular http response.

[Ian Goldberg]

On Thu, Jan 22, 2015 at 04:19:55PM +0100, Mohiuddin Ebna Kawsar wrote:
> Hi,
> 
> Suppose an exit node is acting as Exit for 2 different client connected by
> 2 different middle and guard node.
> suppose one of the client make http get request which will pass through
> Exit and TCP packet Header will be then [SENDER: EXIT NODE IP, RECEIVER:
> WEB-SERVER IP].
> Now we have a reply from web-server. TCP HEADER  [SENDER:WEB-SERVER IP ,
> RECEIVER: EXIT NODE IP].
> 
> as this packet receiver is Exit node now how Exit node decide which relay
> it should pass the response data. means which client this response is for?

You've shown the IP headers above, not the TCP headers.  The TCP header
will show different destination port numbers for the reply packets; the
OS will use those to put the data on the correct socket, and tor knows
which socket belongs to which stream, and so to which circuit.

   - Ian