A Pidgin/libpurple protocol plug-in for Signal using presage.

Contains code from flare by Schmiddi.

Download

See the Releases section on github.

Set-up

1. Create a new Pidgin account. Enter your Signal account UUID as username. In case you do not know your UUID, just enter anything. The plug-in will tell you what to use.
2. Enable the connection. A window with the QR-code should pop-up. Scan it with your master device. Wait for the window to close.

Note: bitlbee users will receive the login QR-code in form of a URI from a system contact "Logon QR Code". You may need to allow unsolicited messages from unknown contacts in your client. The URI can be converted using any tool like a local qrencode or online services (use at your own risk).

Configuration

• startup-delay-seconds int
  Tells the plug-in to wait the specified amount of seconds (default: 1) between spawning the native thread for the rust runtime and actually starting the rust runtime. This magically alleviates database locking issues.

• attachment-path-template string
  This is a template for specifying a path to a local file-name. Setting this to a non-empty value will enable the automated downloader which stores attachments immediately, completely bypassing libpurple's file transfer mechanism. This can be useful for message bridges with limited resources. Also it can help with maintaining the order of messages. Sub-directories will be created as needed.

  Default value is the empty string.

  The template is passed through strftime and accepts time and date format parameters such as %Y-%m-%d_%H:%M:%S. The result may not be longer than 128 bytes! Then the replacements are done:

  • $home: User directory (same as ~).
  • $purple: Purple configuration directory (usually ~/.purple).
  • $direction: Whether this attachment was "received" (sent by a contact) or "sent" (other device on the own account).
  • $chat: The UUID of the contact or key group chat this attachment has been posted to.
  • $sender: The UUID of the contact who posted this attachment to the group chat. Empty if not posted in a group chat.
  • $hash: The file's SHA256 (useful for avoiding clashes and for de-duplication).
  • $filename: The sender-supplied file-name (only for Document messages, otherwise empty). Does not contain the extension.
  • $extension: A file-name extension fitting the mime-type. Includes the dot.

  Example: $purple/presage/attachments/$chat/$filename$hash$extension

  There is no shell expansion (~ will not become the home directory). Relative paths are resolved to the application's working directory. Using an absolute path is recommended.

Features

Present

• Can link as secondary device via QR-Code.
• Receives a simple text message from a contact or a group.
• Displays quotes, reactions and incoming calls.
• Receives attachments. Special handling for long text messages.
• Can send a simple text message.
• Can send an attachment.
• Will add buddies to contact list unconditionally.
• Uses special handling of login procedure for bitlbee.
• Can reply to a specific message via "@searchstring:".
• Some very basic support for Spectrum.

Missing

To Be Done Soon™

• Forward all errors to front-end properly.

On Hold

• Fetch contact names from the main device.
• Mark messages as "read". This is currently not implemented in back-end, see #141. At time of writing, notifications on main device are deleted after answering via linked device. So that is working alright.
• A group chat is only added to the buddy list when receiving a message. There seems to be no way to fetch the list of groups from the main device, see #303.
• The maximum allowed length of a text-message is unknown.

"Contributions Welcome"

• Configuration option whether to add contacts to buddy list or not
• Use the hostname (or a user-defined string) as a device name
• Reasonable generation of C headers and rust constants
• Receive stickers, mentions, styles, contact,…
• Display typing notifications
• Display receipts (not important)
• Support for alternative host applications (Bitlbee, Spectrum)
• Support for adding contact via phone number

These lists are not exhaustive.

Known Issues

• When using the main device to send a message to a new contact for the first time, the plug-in does not know the contact yet.
• Contacts are fetched from the main device only once after linking.
• Information about contact names arrive after the first messages.
• Own name is not transferred to the buddy list and therefore not resolved in group chats.
• Sometimes, the database cannot be opened due to locking issues.
• Spectrum support is very flaky. Crashes, infinite loops and silent disconnects may happen. Please keep an eye on your system and check the logs frequently. Issue reports are welcome.

Building

Linux

Install Dependencies

If your distribution is rolling or very recent, the rust compiler might be recent enough. If not, install rust according to the rustup instructions.

Ubuntu and Debian

sudo apt install libpurple-dev libqrencode-dev protobuf-compiler

Alpine

doas apk add rust pidgin-dev libqrencode-dev protoc

Build

git clone --recurse-submodules https://github.com/hoehermann/purple-presage purple-presage
cmake -S purple-presage -B build
cmake --build build
sudo cmake --install build

Windows

purple-presage is known to compile with MSVC 19.30 and rust 1.75. You need the version of rust mentioned in libsignal-service-rs. A newer version will probably work, too. Using the "x86 Native Tools Command Prompt for VS 2022" is recommended.

Dependencies

Install dependencies via vcpkg:

vcpkg.exe install libqrencode:x86-windows-static

protoc needs to be in your PATH. You can install it with any method you like, including vcpkg:

vcpkg.exe install protobuf

Build

Same as Linux build instructions, but may need to modify the configuration:

1. Generate MSBuild project:

    cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_GENERATOR_PLATFORM=WIN32 -DCMAKE_TOOLCHAIN_FILE="…/vcpkg/scripts/buildsystems/vcpkg.cmake" -DVCPKG_TARGET_TRIPLET=x86-windows-static -DRust_CARGO_TARGET="i686-pc-windows-msvc" -S purple-presage -B build
   

   If necessary, the rust tool-chain version can be specified via -DRust_TOOLCHAIN="1.75-i686-pc-windows-msvc".

2. Build, Install and Run:

    cmake --build build
    cmake --install build --config Release
    cmake --build build --target run
   

When using the "Debug" configuration, the linker complains about mismatching configurations. The implications of this are unknown.

Notes

On Windows, purple-presage must be built with MSVC. gcc (via MinGW or MSYS2) has a number of issues such as incompatibility with recent rustc versions and not shipping libbcrypt by default.

Needs a whooping 6 GB of disk space during build! 😳