Re-work URL joining to follow RFC 3986

[bbayles]

This PR updates how the absolute_uri method for objects that use the BasePathMixin.

I think the changes related to issue #245 and PR #263 introduced some unusual and surprising behavior. The issue related to handling relative URLs that start with //, like //segment.ts.

Joining URLs is covered by RFC 3986, which specifically describes the // case. From section 5.4.1:

Python's built-in urllib.parse.urljoin produces the expected result, but m3u8.parse.urljoin does not:

>>> from urllib.parse import urljoin as python_urljoin
>>> from m3u8.parser import urljoin as m3u8_urljoin

>>> m3u8_urljoin('http://a/b/c/d;p?q', '//g')
'http://a//g'

>>> python_urljoin('http://a/b/c/d;p?q', '//g')
'http://g'

This PR updates m3u8 to prefer the standards-based approach.

[bbayles]

This change allows playlists to use additional URL schemes without having to update this list. RFC 8216 does mention at least the data:// scheme.

[mauricioabreu]

Awesome! You remove a line while adding a new feature 👏🏼

[bbayles]

I think files with a leading / were being mis-handled as well.

On a file system, joining /tmp/path/to/somewhere with /entire.ts should produce /entire.ts.

>>> from os.path import join as python_join
>>> python_join('/path/to/somewhere', '/entire1.ts')
'/entire1.ts'

[mauricioabreu]

Agreed

[SeaHOH]

Greatly surprised. So, // should not be in a path string? But I have saw someone did this.

[mauricioabreu]

@SeaHOH maybe Windows paths?

[bbayles]

I think it's fine to use //, it just needs to mean something standard.

[SeaHOH]

A HTTP URL, just like this: https://some.domain//path/to/segmentx.ts, the // is in head of the relative path entires, not a host name.

[bbayles]

I think that particular absolute URL is fine.

The question is, what do you do when you need to have the starting URL http://a/b/c/d;p?q and then are given the relative URL //g?

The answer, going back to 1995 with RFC 1808, has been consistently the same:

• RFC 1808
• RFC 2396
• RFC 3986

[SeaHOH]

Yes, I just told what I have saw, and be curious about how does it work with web player.