bug#44906: Substitute requests fail if URL has trailing slash

[Mark H Weaver <mhw@netris.org>]

Hi,

Ludovic Courtès <ludo@gnu.org> writes:

> Hartmut Goebel <h.goebel@crazy-compilers.com> skribis:
>
>> I propose fixing all places where string-append is used to join URLs,
>> since joining URLs is not the same as string concatenation. We might 
>> restrict our algorithm to only joining a
>> path. <https://tools.ietf.org/html/rfc3986#section-5.2.2> shows the
>> complete algorithm, where this is the relevant part for only joining a
>> path (R.path) to a base URL's path (T.path).
>>
>>                if (R.path starts-with "/") then
>>                   T.path = remove_dot_segments(R.path);
>>                else
>>                   T.path = merge(Base.path, R.path);
>>                   T.path = remove_dot_segments(T.path);
>
> To begin with, we could define ‘url-append’ in (guix http-client), say,
> and use it in (guix scripts substitute).
>
> Eventually it would be nice to have that in (web uri).

Note that 'resolve-uri-reference' in (guix build download) implements
the algorithm specified in RFC 3986 section 5.2.2, for purposes of
supporting HTTP redirects.  Perhaps some of that code will be useful.

     Regards,
       Mark