fix includes parsing

[imposibrus]

fixes #118

My first experience with Rust. I didn't understand why the InvalidIncludeErrorDetails::HostsInsideHostBlock case is needed, but I can fix the code if you suggest a couple of examples for tests)

[quantumsheep]

This would add an host with patterns but empty entries. I'm not sure if it's needed 🤔 global_host by itself may not be needed as we have current_host now.

[quantumsheep]

Suggested change

	let mut current_host: Option<Host> = None;
	let mut current_host = Host::new(vec!["*".to_string()]);

current_host is the global host by default. What about this?

[imposibrus]

@quantumsheep sorry for wasting your time reviewing the previous commit. i think we can simplify this fix to:

if !patterns.contains(&"*".to_string()) {
    is_in_host_block = true;
    hosts.push(Host::new(patterns));
}

after this, everything from Host * will be at global_host. actually i think it's not quite right, but it works for most simple cases.

Offtopic:

While working on the task, I discovered a not quite correct behaviour: according to the specification, the entries below cannot overwrite those already declared above.
I commented out one test case and left the TODO.

Case:

# main.conf
Host *
    User from_main

Include /included.conf

# included.conf
Host included
    User test_included
    HostName included-host

ssh -F main.conf -G included | grep -i user will return user from_main
but Parser.parse() (and Host.apply_patterns() also) uses host.extend_if_not_contained(&global_host); so host fields are not overwritten by the higher priority Host *.
I think we should take into account the order of the entries. I can create a issue for this.

[quantumsheep]

after this, everything from Host * will be at global_host. actually i think it's not quite right, but it works for most simple cases.

I think it's not right too. What about *.example.com?

I think we should just set current host when an host in host is found. Include directives should be handled like an extension of the current file's content.

Wildcards are handled by HostVecExt::apply_patterns.

What do you think? Really sorry to make you change your code multiple times.

[quantumsheep]

Hey! I took the original idea and simplified it in f04c0b4. Thanks a lot!