This change modifies create_trampoline_onion to only include as many available r_tags as there is space left in the trampoline onion payload. Previously we tried to include all passed invoice r_tags of legacy trampoline payments into the payload which caused an user facing exception and payment failure as the onion can only store a max of 400 bytes. A single, single hop r_tag is around 52 bytes and the payload without r_tags is already at ~280 bytes. So usually there is enough space for 2 r_tags. The implementation shuffles the r_tags on each call so the payment will try different route hints on the attempts (fee level increase or user retry). I have logged the following byte sizes of the trampoline onion with a 2 trampoline onion hop and changing amounts of r_tags: 3 rtags: payload size [0]: 113 (hop size: 81) payload size [1]: 440 (hop size: 295) ( 52 bytes/rtag ) payload size [2]: 550 (hop size: 78) 2 rtags: payload size [0]: 113 (hop size: 81) payload size [1]: 386 (hop size: 241) ( 52 bytes/rtag ) payload size [2]: 496 (hop size: 78) 1 rtag: payload size [0]: 113 (hop size: 81) payload size [1]: 334 (hop size: 189) ( 52 bytes/rtag ) payload size [2]: 444 (hop size: 78) 0 rtags: payload size [0]: 113 (hop size: 81) payload size [1]: 282 (hop size: 137) payload size [2]: 392 (hop size: 78) As can be seen in the data, using 2 trampoline hops there is not enough space for even a single r_tag which is why this option is being removed too.
Electrum - Lightweight Bitcoin client
Licence: MIT Licence
Author: Thomas Voegtlin
Language: Python (>= 3.10)
Homepage: https://electrum.org/
Getting started
(If you've come here looking to simply run Electrum, you may download it here.)
Electrum itself is pure Python, and so are most of the required dependencies, but not everything. The following sections describe how to run from source, but here is a TL;DR:
$ sudo apt-get install libsecp256k1-dev
$ ELECTRUM_ECC_DONT_COMPILE=1 python3 -m pip install --user ".[gui,crypto]"
Not pure-python dependencies
Qt GUI
If you want to use the Qt interface, install the Qt dependencies:
$ sudo apt-get install python3-pyqt6
libsecp256k1
For elliptic curve operations, libsecp256k1 is a required dependency.
If you "pip install" Electrum, by default libsecp will get compiled locally,
as part of the electrum-ecc dependency. This can be opted-out of,
by setting the ELECTRUM_ECC_DONT_COMPILE=1 environment variable.
For the compilation to work, besides a C compiler, you need at least:
$ sudo apt-get install automake libtool
If you opt out of the compilation, you need to provide libsecp in another way, e.g.:
$ sudo apt-get install libsecp256k1-dev
cryptography
Due to the need for fast symmetric ciphers, cryptography is required. Install from your package manager (or from pip):
$ sudo apt-get install python3-cryptography
hardware-wallet support
If you would like hardware wallet support, see this.
Running from tar.gz
If you downloaded the official package (tar.gz), you can run Electrum from its root directory without installing it on your system; all the pure python dependencies are included in the 'packages' directory. To run Electrum from its root directory, just do:
$ ./run_electrum
You can also install Electrum on your system, by running this command:
$ sudo apt-get install python3-setuptools python3-pip
$ python3 -m pip install --user .
This will download and install the Python dependencies used by
Electrum instead of using the 'packages' directory.
It will also place an executable named electrum in ~/.local/bin,
so make sure that is on your PATH variable.
Development version (git clone)
(For OS-specific instructions, see here for Windows, and for macOS)
Check out the code from GitHub:
$ git clone https://github.com/spesmilo/electrum.git
$ cd electrum
$ git submodule update --init
Run install (this should install dependencies):
$ python3 -m pip install --user -e .
Create translations (optional):
$ sudo apt-get install python3-requests gettext qt6-l10n-tools
$ ./contrib/pull_locale
Finally, to start Electrum:
$ ./run_electrum
Run tests
Run unit tests with pytest:
$ pytest tests -v
To run a single file, specify it directly like this:
$ pytest tests/test_bitcoin.py -v
Creating Binaries
Contributing
Any help testing the software, reporting or fixing bugs, reviewing pull requests and recent changes, writing tests, or helping with outstanding issues is very welcome. Implementing new features, or improving/refactoring the codebase, is of course also welcome, but to avoid wasted effort, especially for larger changes, we encourage discussing these on the issue tracker or IRC first.
Besides GitHub,
most communication about Electrum development happens on IRC, in the
#electrum channel on Libera Chat. The easiest way to participate on IRC is
with the web client, web.libera.chat.