Add feature to get HTTP OPTIONS

[brimstone]

This adds a -opt feature to reveal HTTP OPTIONS.
I needed to be able to find dav shares for a CTF.
I didn't find any other tool that would do this, so I modified gobuster.

[OJ]

Thanks @brimstone. So is the intent here to just be able to discover the options available? Would it be worth adding filters here so that people can specify which options they're looking for in particular?

[brimstone]

Correct, the intent is to use the HTTP method OPTIONS to discover the HTTP methods available to each directory or file discovered. Now that I type this out, maybe the flag should be -methods? There's <20 different possible http methods possible, and in practice there's <5 that keep showing up. I don't know that it makes sense to filter only matching methods, but maybe filter out the common: HEAD, GET, POST, OPTIONS methods. Another route could be a more explicit -dav option that determines if webdav is supported based on the methods returned by HTTP OPTIONS. What do you think?

[OJ]

Sorry for not getting back to you earlier. I think it'd be great to be able to pass in a CSV of methods. From there people can use custom ones as well (given that it's possible to have custom methods in various services). The -dav option sounds nice but I say let's keep it simple to start with.

[OJ]

Hi @brimstone sorry for the tardiness. I've landed a chunky refactor to the code, so would it be possible for you to update this PR so it's rebased on master? Thank you!

[brimstone]

I'm looking into this now.

[brimstone]

All I've done is rework this to account for the refactor to 1.4. This is still simply showing the server methods supported for a URL and not filtering them with just what the user is requesting. I can add that if it's still desired, but it'll make the code longer.

[0xdevalias]

Potentially related, may be relevant to consider with regards to this PR:

• Arbitrary headers, POST support, POST body support, Content-Type support, linting #76

[OJ]

Apologies for the delay on this, can I please request that you rebase your changes on 2.0.0 now that I've finally landed #79? Thank you so much.