I'm working on a patch for antinat, to make it do some cool/weird stuff that it can't do at the moment.
In case you're wondering antinat is a great implementation of a socks server. It supports socks4, socks5 with user/password authentication, accept/reject acls based on user or ip, easy configuration in an XML file and it's also multithreaded ( ok maybe this is not so great for some but I like it ).
I'm not going to write about the patch I'm working on but maybe I'll write about that in another post.
While I was looking over it's source code I found this funny comment right before a function that was used to handle the SIGPIPE signal:
- UNIX trivia - when is a problem a problem? When you don't ignore it.
- If you do nothing, well, you're not being ignorant enough. You have
- to be explicitly ignorant.
This is funny but the comment has a good point. If you write an application and it tries to write to a connection that was closed, your program will receive a signal with the code SIGPIPE, which means ( according to the man page of the kill program) that if the proces does not have a default handler for SIGPIPE then it will just exit. So there you have a big problem.
The simple solution is to just set your own signal handler for SIGPIPE . So you have to set a function that will be called when the program receives a SIGPIPE and your function doesn't really have to do anything about it, so it will just ignore it and reset the handler to itself.
- ignorer (int x)
- signal (x, ignorer);
But if you don't explicitly set this, your process will just die upon receiving a SIGPIPE and you really don't want that especially when writing server applications.