`Require all denied` (or other equivalent directive for the `http` server
in use), and a `403` error handler of `{$cgiurl}?do=view`.
+The plugin emits response headers intended to discourage non-private caches
+from retaining the retrieved content. (They are already supposed to avoid
+caching any response to a request with an `Authorization` header, but this
+plugin can be used with any ikiwiki-supported auth method, not all of which
+require that header.)
+
A plugin like [[plugins/contrib/pagespec_alias]] can be very useful for
defining a group of authorized users:
[Authorizer](http://www.fastcgi.com/drupal/node/6?q=node/22#S6.3) could provide
the same benefits as [[plugins/contrib/signinview]] (any ikiwiki-supported auth
method, simple zone definition with [[ikiwiki/PageSpec]]s) with less overhead
-per access.
+per access. It would also be simpler than [[plugins/contrib/signinview]] by
+leaving it as the `http` server's responsibility to generate the proper headers
+and serve the content.
+
+Caching proxies are already supposed to avoid caching any response to a request
+that included an `Authorization` header. For some ikiwiki-supported auth methods,
+that header might not be needed in the request, and care may be needed to configure
+the server to emit other necessary response headers to discourage caching of
+content from a private zone.
+
+*Drawbacks:* Not yet implemented, someone would have to do it.
+It's not clear [[what code changes fastcgi|todo/fastcgi or modperl installation instructions]]
+would require in ikiwiki. An Authorizer seems like a good place to start because of its
+limited, simple functionality--but as it could make use of any ikiwiki-supported auth method,
+evaluate `PageSpec`s, and the like, it could still run a non-trivial amount of the code.
## Obstacles
Note that not all of these issues will be problems for all **zoned ikiwiki use cases**.
+### Leakage of page existence by `do=goto`
+
+An unauthorized client can use a `do=goto` request to find out whether a
+page exists (will be forbidden to view it) or not (will be forbidden to create it).
+
+In [[plugins/contrib/signinview]] this is handled by hooking
+`cgi` first and checking for `goto` and a non-public page. If the requested page
+(existing or not) matches the `public_pages` PageSpec, it is handed off for the `goto`
+plugin to handle normally. Otherwise, the `do` parameter is changed to `signingoto`
+so the `goto` plugin's `cgi` hook will _not_ handle it, and the `sessioncgi` hook
+takes care of it when the user's identity is available.
+
### Backlinks
What is problematic is when you link a public page in a private page :
* Not to forget `contrib` plugins
* [[plugins/contrib/report]] ?
* _others_?
+
+Note that, _with_ the right controls on who can edit the pages and insert
+the directives, the fact that a public page can inline stuff from private
+pages can be very useful. Public pages can be created that are populated
+by selected content that's maintained on the private side. The [[ikiwiki/directive/if]]
+directive can be used in the private content to control what parts can be
+inlined into public pages. All of this is in ikiwiki today.