Proton Drive WebDAV Bridge

An alternative approach to interacting with Proton Drive on Linux.

Instead of integrating the Proton Drive API into a tool like rclone, this program will expose a local interface to it using the WebDAV protocol. This approach has two benefits over the existing backend in rclone:

• You can use any client that supports WebDAV (even though rclone is still the recommended one, for reasons explained below)
• Because the bridge runs as a daemon, it can cache the entire directory tree and only update it when required, through the event system of Proton Drive. This enables near instant directory listings through WebDAV.

Disclaimer

This software is experimental and mostly untested.

While I do use it for myself, I cannot guarantee that it won't try to eat your data. Please proceed with caution and backups.

Installation

To build this software, you need a recent Go toolchain (1.18 or newer) and git.

$ go version
go version go1.21.5 linux/amd64
$ git --version
git version 2.43.0

Building and installing the bridge is mostly automatic. You can use the GOBIN environment variable to select the target directory. I recommend using $HOME/.local/bin because it is fairly standard and most likely already part of the PATH variable in your shell. If you use a different target, you must make sure it is part of PATH.

$ git clone https://github.com/StollD/proton-webdav-bridge
$ cd proton-webdav-bridge
$ env GOBIN="$HOME/.local/bin" go install .

Login

Before using the bridge, you need to provide it with your credentials and let it generate a login token. Only the token will be stored, not your username or password.

Run the following command and follow the instructions it prints to your terminal.

$ proton-webdav-bridge --login

Running the bridge

Running the WebDAV bridge is as simple as running the program without any arguments.

$ proton-webdav-bridge

By default, the WebDAV server will listen on http://127.0.0.1:7984, but you can change this with the --addr option.

Depending on the amount (not the size!) of files and directories in your drive, the startup might take quite a while, because the bridge is caching the metadata of all objects, to speed up WebDAV lookups.

For starting the bridge automatically when you log in, I recommend using a systemd user service. A basic service file that you can use is in the systemd directory of this repository.

Download it into $HOME/.config/systemd/user, and create the directory if it doesn't exist. Then enable it like this.

$ systemctl --user daemon-reload
$ systemctl --user enable --now proton-webdav-bridge.service

Keep in mind that this service will only work if you installed the bridge to $HOME/.local/bin. If you changed the path, you need to adjust the service file as well.

WebDAV, Clients and Rclone

The WebDAV standard does not include support for fetching file hashes, which makes it less suitable for a two-way sync, because the client has to guess if two files are identical based on the modification time.

There is also no standard way for the client to set the modification time, which means that uploading existing files resets their modification time.

To bridge this gap, the bridge implements a few extensions:

• Modification time can be set through a X-OC-Mtime header (OwnCloud extension)
• The SHA1 of a file can be read through the checksums property (OwnCloud extension)
• The SHA1 of a file can be read through the sha1hex property (FastMail extension)

To make full use of these extensions, you should use the rclone WebDAV backend and configure its vendor type to fastmail. This maps pretty much 1:1 to what Proton Drive and this bridge support and will provide the best experience.

If there are any other clients that support these extensions, or if there are useful extensions I missed, please open an issue or send a pull request!

Thanks

• henrybear327 for publishing https://github.com/henrybear327/Proton-API-Bridge
• Proton for publishing https://github.com/ProtonMail/go-proton-api