[webkit-gtk] Can't find a way to implement content blocking (filtering)

[Michael Catanzaro]

On Tue, May 4 2021 at 08:07:00 AM +0200, linuxfan at tin.it wrote:
> I noticed that there is a very similar signal also in
> webkit, but to use it one has to use an extension which, it seems to
> me, has to be an external library. Even if I could try to write and
> compile a similar library, then the dialog between the library and the
> main application would be quite complicated, I think.

This is the only way to do it. You need to use the 
WebKitWebPage::send-request signal. Return TRUE to cancel the resource 
load, or FALSE to continue the load. WebKitWebPage is a web process 
object: you wouldn't want this API in the UI process because then the 
web process to have to wait on IPC to the UI process for every single 
resource to be loaded.

Writing a web process extension is easy, don't worry. Especially so 
when you only have one signal to implement. There are plenty of 
examples out there, e.g.:

https://gitlab.gnome.org/GNOME/epiphany/-/blob/6be2365125f7c3710635aabb1aeed420df5d84c7/embed/web-process-extension/ephy-web-process-extension.c.

Except your extension will be much simpler than that. You connect to 
WebKitWebExtension::page-created in your 
WebKitWebKitensionInitializeFunction, and in your page-created callback 
you can connect to WebKitWebPage::send-request. And that's about it.

Compiling it into a shared object is easy too, e.g.:

https://gitlab.gnome.org/GNOME/epiphany/-/blob/6be2365125f7c3710635aabb1aeed420df5d84c7/embed/web-process-extension/meson.build#L23

Good luck,

Michael