84 lines
3.6 KiB
Text
84 lines
3.6 KiB
Text
|
After an all-nighter, I have `git annex webapp` launching a WebApp!
|
||
|
|
|
||
|
|
It doesn't do anything useful yet, just uses Yesod to display a couple of
|
||
|
|
hyperlinked pages and a favicon, securely.
|
||
|
|
|
||
|
|
The binary size grew rather alarmingly, BTW. :) Indeed, it's been growing
|
||
|
|
for months..
|
||
|
|
|
||
|
|
-rwxr-xr-x 1 root root 9.4M Jul 21 16:59 git-annex-no-assistant-stripped
|
||
|
|
-rwxr-xr-x 1 joey joey 12M Jul 25 20:54 git-annex-no-webapp-stripped
|
||
|
|
-rwxr-xr-x 1 joey joey 17M Jul 25 20:52 git-annex-with-webapp-stripped
|
||
|
|
|
||
|
|
----
|
||
|
|
|
||
|
|
Along the way, some Not Invented Here occurred:
|
||
|
|
|
||
|
|
I didn't use the yesod scaffolded site, because it's a lot of what
|
||
|
|
seems mostly to be cruft in this use case. And because I don't like
|
||
|
|
code generated from templates that people are then expected to edit. Ugh.
|
||
|
|
That's my least favorite part of Yesod. This added some pain, since
|
||
|
|
I had to do everything the hard way.
|
||
|
|
|
||
|
|
I didn't use [wai-handler-launch](http://hackage.haskell.org/package/wai-handler-launch)
|
||
|
|
because:
|
||
|
|
|
||
|
|
* It seems broken on IPv6 capable machines (it always opens
|
||
|
|
`http://127.0.0.1:port/` even though it apparently doesn't always
|
||
|
|
listen there.. I think it was listening on my machine's ipv6 address
|
||
|
|
instead. I know, I know; I should file a bug about this..)
|
||
|
|
* It always uses port 4587, which is **insane**. What if you have two
|
||
|
|
webapps?
|
||
|
|
* It requires javascript in the web browser, which
|
||
|
|
is used to ping the server, and shut it down when the web browser closes
|
||
|
|
(which behavior is wrong for git-annex anyway, since the daemon should
|
||
|
|
stay running across browser closes).
|
||
|
|
* It opens the webapp on web server startup, which is wrong for git-annex;
|
||
|
|
instead the command `git annex webapp` will open the webapp,
|
||
|
|
after `git annex assistant` started the web server.
|
||
|
|
|
||
|
|
Instead, I rolled my own WAI webapp laucher, that binds to any free port
|
||
|
|
on localhost, It does use `xdg-open` to launch the web browser,
|
||
|
|
like wai-handler-launch (or just `open` on OS X).
|
||
|
|
|
||
|
|
Also, I wrote my own WAI logger, which logs using System.Log.Logger,
|
||
|
|
instead of to stdout, like `runDebug` does.
|
||
|
|
|
||
|
|
----
|
||
|
|
|
||
|
|
The webapp only listens for connections from localhost, but that's
|
||
|
|
not sufficient "security". Instead, I added a secret token to
|
||
|
|
every url in the webapp, that only `git annex webapp` knows about.
|
||
|
|
|
||
|
|
But, if that token is passed to `xdg-open` on its command line,
|
||
|
|
it will be briefly visible to local attackers in the parameters of
|
||
|
|
`xdg-open`.. And if the web browser's not already running, it'll run
|
||
|
|
with it as a parameter, and be *very* visible.
|
||
|
|
|
||
|
|
So instead, I used a nasty hack. On startup, the assistant
|
||
|
|
will create a html file, readably only by the user, that redirects
|
||
|
|
the user to the real site url. Then `git annex webapp` will run
|
||
|
|
xdg-open on that file.
|
||
|
|
|
||
|
|
----
|
||
|
|
|
||
|
|
Making Yesod check the `auth=` parameter (to verify that the secret token
|
||
|
|
is right) is when using Yesod started to pay off. Yesod has a simple
|
||
|
|
`isAuthorized` method that can be overridden to do your own authentication
|
||
|
|
like this.
|
||
|
|
|
||
|
|
But Yesod really started to shine when I went to add the `auth=` parameter
|
||
|
|
to every url in the webapp. There's a `joinPath` method can can be used
|
||
|
|
to override the default url builder. And every type-safe url in the
|
||
|
|
application goes through there, so it's perfect for this.
|
||
|
|
|
||
|
|
I just had to be careful to make it not add `auth=` to the url for the
|
||
|
|
favicon, which is included in the "Permission Denied" error page. That'd be
|
||
|
|
an amusing security hole..
|
||
|
|
|
||
|
|
----
|
||
|
|
|
||
|
|
Next up: Doing some AJAX to get a dynamic view of the state of the daemon,
|
||
|
|
including currently running transfers, in the webapp. AKA stuff I've never
|
||
|
|
done before, and that, unlike all this heavy Haskell Yesod, scares me. :)
|