# Parasite - live along side a process. Die when it dies.
## Example: Serving a HTTP from /bin/sleep.
% PARASITE_RUBY=./sinatra-example.rb LD_PRELOAD=./parasite.so sleep 360
Parasite initialized by hooking 'malloc'
== Sinatra/1.1.0 has taken the stage on 4567 for development with backup from Thin
>> Thin web server (v1.2.7 codename No Hup)
>> Maximum connections set to 1024
>> Listening on 0.0.0.0:4567, CTRL+C to stop
127.0.0.1 - - [01/Feb/2011 19:10:25] "GET / HTTP/1.1" 200 12 0.0019
127.0.0.1 - - [01/Feb/2011 19:10:25] "GET /favicon.ico HTTP/1.1" 404 420 0.0008
% curl localhost:4567; echo
User time: 0.78<br>
System time: 0.16
## Possible use cases:
* Expose internal-process data from any process over HTTP, etc, without needing
to modify said program - and without requiring root access necessarily to access it.
* Allow coordinated handoff of server sockets without modifying the main
program (this will be tricky, but should work nicely)
* Embed a script runtime (ruby, python, perl, nodejs, etc) into any running program.
## Example: Inspect netcat's socket.
% PARASITE_RUBY=irb-example.rb LD_PRELOAD=./parasite.so nc -l 192.168.0.97 8888
Parasite initialized by hooking 'malloc'
>> require "socket"
=> true
>> sock = Socket.for_fd(3)
=> #<Socket:0x7f8a795833c8>
>> port, address = Socket.unpack_sockaddr_in(sock.getsockname)
=> [8888, "192.168.0.97"]