Error when parsing sudoers configuration with domain groups / groups with "@domain"

[mpibpc-mroose]

Describe the bug
sudo-rs seems to be unable to work with active directory domain groups in sudoers files. Seems it stumbles upon the @ when parsing those files.

To Reproduce
Steps to reproduce the behavior:

1. Install ' sudo-rs` on Ubuntu 24.04 using apt
2. Use the default contents in /etc/sudoers-rs
3. Create a sudoers configuration such as /etc/sudoers.d/01_server_admins_group

%linuxadmins@example.com   ALL=(ALL) NOPASSWD: ALL

5. Run the following command sudo-rs ls
6. See error:

/etc/sudoers.d/01_server_admins_group:2:13: expected host name
%linuxadmins@example.com   ALL=(ALL) NOPASSWD: ALL
            ^                  

[squell]

Thanks for opening this issue. For user names I based the tokeniser on the available info (e.g. a user name is an alphanumeric string which might contain dots, underscores & hyphens).

Also see https://systemd.io/USER_NAMES/

Maybe we should also allow the $ sign as a final character in user names?

[squell]

Note: a general solution allowing @ in the syntax introduces a truly locally ambiguous grammar, since then we can not distinguish (easily) between:

Defaults@host setting=value
username@domain hostname=rule

E.g.

Defaults@domain env_keep=ALL

does that grant a permission to run all commands on the server env_keep to the user Defaults@domain? Of course not.

This is not a problem in the cited example above since it involves groups and those start with % which is unambiguous. So my proposed solution would be as follows:

• Create a seperate Groupname token that is like Username but also accepts @.
• Add support for @ in usernames using escape sequences, e.g. allowing them but they would have to be surrounded by quotes to resolve the ambiguity.
• And like mentioned previously, probably also accept $ as the final character, since apparently those can happen.

[squell]

Alright, so since the Defaults syntax was already ambiguous, we can lean into that and it's probably actually not as messy to fix.

[squell]

Fixed by #1065