For security reasons, one of the sites I'm in charge of uses a Reverse Proxy to grab the content from another machine behind our firewall.
Let's call the out-facing machine Alfred and the one behind the firewall Betty.

For the static pages, everything is fine.  However, when trying to use the search, all the links break.
This is because, when Alfred passes the search query on to Betty, the search result has a "base" tag which points to Betty, and all the links to the "found" pages are relative.
So we have

    <base href="Betty.example.com"/>
    ...
    <a href="./path/to/found/page/">path/to/found/page</a>

This breaks things for anyone on Alfred, because Betty is behind a firewall and they can't get there.

What would be better is if it were possible to have a "base" which didn't reference the hostname, and for the "found" links not to be relative.
Something like this:

    <base href="/"/>
    ...
    <a href="/path/to/found/page/">path/to/found/page</a>

The workaround I've come up with is this.

1. Set the "url" in the config to '&nbsp;' (a single space).  It can't be empty because too many things complain if it is.
2. Patch the search plugin so that it saves an absolute URL rather than a relative one.

Here's a patch:

    diff --git a/IkiWiki/Plugin/search.pm b/IkiWiki/Plugin/search.pm
    index 3f0b7c9..26c4d46 100644
    --- a/IkiWiki/Plugin/search.pm
    +++ b/IkiWiki/Plugin/search.pm
    @@ -113,7 +113,7 @@ sub indexhtml (@) {
            }
            $sample=~s/\n/ /g;
    
    -       my $url=urlto($params{destpage}, "");
    +       my $url=urlto($params{destpage}, undef);
            if (defined $pagestate{$params{page}}{meta}{permalink}) {
                    $url=$pagestate{$params{page}}{meta}{permalink}
            }

It works for me, but it has the odd side-effect of prefixing links with a space.  Fortunately that doesn't seem to break browsers.
And I'm sure someone else could come up with something better and more general.

--[[KathrynAndersen]]

> The `<base href>` is required to be genuinely absolute (HTML 4.01 §12.4).
> Have you tried setting `url` to the public-facing URL, i.e. with `alfred`
> as the hostname? That seems like the cleanest solution to me; if you're
> one of the few behind the firewall and you access the site via `betty`
> directly, my HTTP vs. HTTPS cleanup in recent versions should mean that
> you rarely get redirected to `alfred`, because most URLs are either
> relative or "local" (start with '/'). --[[smcv]]

>> I did try setting `url` to the "Alfred" machine, but that doesn't seem clean to me at all, since it forces someone to go to Alfred when they started off on Betty.
>> Even worse, it prevents me from setting up a test environment on, say, Cassandra, because as soon as one tries to search, one goes to Alfred, then Betty, and not back to Cassandra at all.
>> Hardcoded solutions make me nervous.

>> I suppose what I would like would be to not need to use a `<base href>` in searching at all.
>> --[[KathrynAndersen]]

>>> `<base href>` is *not* required to be absolute in HTML5, so when
>>> `html5: 1` is used, I've changed it to be host-relative in most cases.
>>> I think that at least partially addresses this bug report,
>>> particularly if we [[todo/generate HTML5 by default]] like I've suggested.
>>>
>>> The `<base>` is there so we can avoid having to compute how to
>>> get to (the virtual directory containing) the root of the wiki from
>>> `ikiwiki.cgi`, which might well be somewhere odd like `/cgi-bin/`.
>>> I think there are probably other things that it fixes or simplifies.
>>> --[[smcv]]
