Re: Implementation sketch for Ncat caretaker processes

[venkat sanaka <venkatsanaka () gmail com>]

The above technique costs two processes per connection. You could do it

> with less overhead if you create the pipes and fork a subprocess when a
> connection is received, then add the read end of the pipe connected to
> stdout of the child process to the select set. When select indicates
> that a decriptor is ready, there would be four cases:
>
>        1. The listening socket
>        2. A connected client socket.
>        3. The server's own stdin.
>        4. The stdout of a child process.
>
> In case 2, you would read from the socket and write to the pipe of its
> corresponding process. In case 4, you would read from the pipe and write
> to its corresponding socket.

This approach will have a overhead of maintaining the pipe information
corresponding to a socket and retrieving it in case 2 for writing to the
pipe.
In case 4, we use the same pipe info to check whether the ready descriptor
is, stdout of child process(read end of the pipe) or not.
   I too think, this technique has less overhead when compared to the other
one.
We need to change the existing read and write functions, where reading
from only STDIN and writing to all connected sockets(broadcast) is happening
as of now.Also we have to add pipe info to fdinfo struct present in util.h,
  I am working on this approach and it's almost done.I will commit it to my
nmap-exp branch for your review, after testing it once.

Regards
Venkat
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