Serve local files via "http://localhost/" URLs.
The Local File Server extension enables web sites to link to local files via "http://localhost/"; URLs. For security reasons, Chrome disables links to local files (i.e., "file://" links) in remote web pages. Some web services, like for instance Gmail, don't even render such links. Though, there are circumstances where such links are secure and desirable. For example, a process may want to send execution logs via email that contain links to local files. Thanks to this extension these links can be replaced with "http://localhost/"; links that will be rendered by all web services, that won't be blocked by Chrome, and that the extension will redirect to the desired local file.
The syntax for local file links is "http://localhost/file.html?path=<file-path>[&access-key=<access-key>]";, where <file-path> is the absolute path to the desired local file and <access-key> an optional confidential access key that enables the extension to automatically redirect to the local file. If the access key isn't provided or the one provided doesn't match the extension's access key, the extension renders a page with a "file://<file-path>" link and a warning to only click on the link if one was brought there via a trusted party.
When the extension is installed, a cryptographically secure access key is generated and stored in the extension. It can be viewed and changed on the extension's options page. The key must be kept confidential to prevent malicious actors from being able to craft valid links to local files. The key should only be shared with trusted parties that need to create links to local files.