What I do not understand is that disabling the `format` function (by commenting [[line 46 of the plugin|https://github.com/paternal/ikiwiki-rpcbug/blob/master/plugins/rpcbug#L46]]) solves the problem. Half of an explaination is that I think that when the the ``proxy.rpc`` function is called, the RPC communication is messed up in such a way that the `format` function is not called, and the return value of `preprocess` is considered to be the whole html code of the resulting page.
+> I understood that: as the first rpc call messes up the communication, more rpc calls are messed up, but if there is only one rpc call, not that much is broken. -- [[Louis|spalax]]
+
I hope someone will understand the problem better than I do, because I have no idea about how to solve this.
Regards,
--- Louis
+-- [[Louis|spalax]]
+
+> I used the debug feature provided with `proxy.py` and rebuilt the wiki. I ran this with [this version](https://github.com/paternal/ikiwiki-rpcbug/tree/b4ba34a8edd1b97989965af69eddac050bc0a8ba) of my minimal bug example.
+>
+> * The bug happens in function [preprocess](https://github.com/paternal/ikiwiki-rpcbug/blob/b4ba34a8edd1b97989965af69eddac050bc0a8ba/plugins/rpcbug#L12-17) (in call to [srcfile](https://github.com/paternal/ikiwiki-rpcbug/blob/b4ba34a8edd1b97989965af69eddac050bc0a8ba/plugins/rpcbug#L15), to be more precise).
+> * The directive causing the bug is called on page [foo](https://github.com/paternal/ikiwiki-rpcbug/blob/b4ba34a8edd1b97989965af69eddac050bc0a8ba/foo.mdwn).
+> * Communication between Ikiwiki and the plugin is [[here|debug]].
+> * The resulting HTML (for page `foo`) looks like:
+>
+> > \[[!rpcbug Erreur: internal error: foo cannot be found in /home/louis/projets/ikiwiki/rpcbug or underlay]]
+> >
+> >
+> > Calling srcfile(foo): page
+> > Calling srcfile(README.md): /home/louis/projets/ikiwiki/rpcbug/README.md
+>
+> My analysis:
+>
+> * The call to `srcfile(foo)` fails (because Ikiwiki thinks that page `foo` does not exist).
+> * Ikiwiki thinks that processing of the directive is finished, whereas the plugin still waits for the answer of Ikiwiki.
+> * Ikiwiki asks the plugin to render a new directive, but the plugin interprets the request as the return value for its previous request. Thus, the plugin thinks that `srcfile(foo)` is `page` (this `page` being a misinterpretation of the Ikiwiki request).
+>
+> So, I think that this might be an error in the
+> [`rpc_call`](https://github.com/joeyh/ikiwiki/blob/9476e2ac7ad2f53643fa2fca6ba35fcc55ab058e/IkiWiki/Plugin/external.pm#L46-147)
+> function of the `external` plugin: when the called method fails, it should
+> return something (or raise an exception, if this is possible in RPC) to notify
+> the plugin that something went wrong.
+>
+> -- [[Louis|spalax]]
+
+>> Update: This can actually be a [proxy](https://github.com/joeyh/ikiwiki/blob/9c910a76e70111c50ba8cbb518277f809fc1d09d/plugins/proxy.py) error. Indeed:
+>>
+>> - Ikiwiki sends a `methodCall` message to the plugin (which is a call to the
+>> `preprocess` function);
+>> - the plugin sends a `methodCall` message to ikiwiki (which is a call to the
+>> `srcfile` function);
+>> - Ikiwiki answers with a `methodCall` message:
+>> - Ikiwiki answers this because the function call failed, and it is already
+>> processing the next directive;
+>> - the plugin thinks that it is its request answer, and misinterprets it.
+>>
+>> Thus, I think that the bug is in the `proxy.py` python file. On receiving a
+>> `methodCall` (instead of a `methodResponse`) as an answer to a `methodCall`
+>> request, `proxy.py` should notice the type of request, and call the requested function.
+>>
+>> I know Python better than I know Perl, so I can try to fix this.
+>>
+>> -- [[Louis|spalax]]
+
+>>> [[!template id=gitbranch author="[[Louis|spalax]]" branch=spalax/paternal/rpcbug
+>>> browse=https://github.com/paternal/ikiwiki/tree/paternal/rpcbug]]
+>>> [I fixed this bug](https://github.com/paternal/ikiwiki/commit/32da347566a7559ca1ef145880efe961dbcc012f) in a branch on my Ikiwiki clone.
+>>> Please review :)
+>>>
+>>> -- [[Louis|spalax]]