Telepathy for Delta Chat

Who

Authored by Nick Thomas under the MIT License.

What

Delta Chat is IM over email. Telepathy is a framework for abstracting over multiple IM protocols. This project glues the two together, allowing Telepathy clients to send/receive Delta messages.

Telepathy CMs should have a name that is not the same as their protocol; so this CM is hereby named "padfoot".

My first attempt was purple-plugin-delta. This has some licensing issues (linking libpurple with OpenSSL) that will be resolved with OpenSSL v3.0.0. At least until then, I've lost interest in it; my efforts are going into this version instead.

When

When it's ready.

Where

Here's where we're at right now:

• Connect to DBUS
• Advertise enough properties / interfaces to become visible in Empathy
• Connect to deltachat-core-rust
• Set up an account via autoconfiguration
• Appear as online in Empathy
• Disconnect!
• Set up an account manually
• Contacts handling
• Text messages
• Multimedia messages
• Setup messages
• Import/Export
• Group chats
• Geolocation messages

Why

Mobile IM, mostly. Desktop IM, also. It's ideal for my pinephone, and lighter than the electron desktop client.

At this point, I don't know Rust, I don't know DBUS, I don't know Telepathy, and I don't know Deltachat particularly well either. So this also functions as a learning exercise!

How

Compiling

This project is written in Rust, so you'll need a rust compiler to build it. Rustup comes highly recommended.

There is a rust-toolchain file that I try to keep synced with the version of rust that deltachat-core-rust uses.

Once you have a working rust compiler, just:

$ cargo build --release

to get a `telepathy-padfoot binary. Drop the release flag to make it build fast.

Cross-compiling amd64 -> i386

If you need a 32-bit binary and you're on an am64 bit system, this seems to work, as long as you have 32-bit versions of libdbus-1 and libssl installed.

On Debian, the full sequence looks like:

$ dpkg --print-architecture
amd64
# dpkg --add-architecture i386
$ dpkg --print-foreign-architectures
i386
# apt update
# apt install libdbus-1-dev:i386 libssl-dev:i386
$ rustup target install i686-unknown-linux-gnu
$ PKG_CONFIG_ALLOW_CROSS=1 cargo build --target=i686-unknown-linux-gnu --release

This creates a 32-bit executable at target/i686-unknown-linux-gnu/release/telepathy-padfoot

I don't have a 32-bit machine to test this on, but happy to take fixes for it.

Installing

There is a share/ directory in this project that contains a bunch of files. They should be placed into /usr/share, following the same layout. Then put the binary into /usr/lib/telepathy/telepathy-padfoot.

I should probably put this into the makefile.

Autogenerated telepathy DBUS bindings

It makes use of the dbus-codegen-rust crate to convert the telepathy interface specs into the executable code in src/telepathy. This is checked in, but can be regenerated like so:

$ git submodule init telepathy-spec
$ git submodule update telepathy-spec
$ cargo install dbus-codegen
$ ./scripts/dbus-codegen

dbus-codegen-rust doesn't seem to handle namespaced attributes properly, so we modify the XML files in telepathy-spec... with sed. The tp:type attribute is renamed to tp:typehint.