fixes https://github.com/spesmilo/electrum/issues/8813
regression from eef9680743
We started setting the witness field in above commit to be able to provide the witnesses for already pre-signed
external inputs to the device, e.g. for a coinjoin.
Trezor One fw has pretty strict limits on the witness field: max 109 bytes,
probably because that's a ~tight upper bound for a p2wpkh witness:
<num_witness_items> <len(sig)> <sig> <len(pubkey)> <pubkey>, it comes out to 3+73(high-S and high-R)+33.
ed1785a985/legacy/firmware/protob/messages-bitcoin.options (L35)
Trezor model T seems to have higher limits.
tx_inputs is called for the tx being signed (for_sig=True), and for its parents/prev_txes (for_sig=False).
The witness is only useful for the tx being signed, I think.
Users reported seeing a "DataError: bytes overflow" exception when using a Trezor One to sign 2of3 p2wsh multisig txs.
There were no external inputs involved so for the tx being signed all witnesses were None, however we were also
setting the witness for the inputs of prev_txes.
The witness for a 2of3 pw2sh multisig input is around ~253 bytes.
To sidestep the problem, we now only set the witness in the for_sig=True case.
Note that this means if someone tries to do a coinjoin with a Trezor One involving non-trivial external inputs,
they will run into the same limit and exception.
pyinstaller tries to import electrum and its different submodules at build-time
during the "Analysis" phase. sys._GUI_QT_VERSION was not getting set there,
and the resulting exception was blocking pyinstaller from discovering that
gui/common_qt is being used.
at runtime:
```
$ ./dist/Electrum.app/Contents/MacOS/run_electrum
1.53 | E | daemon.Daemon | GUI raised exception: Exception('Error loading trustedcoin plugin: ModuleNotFoundError("No module named \'electrum.gui.common_qt\'")'). shutting down.
1.53 | E | __main__ | daemon.run_gui errored
Traceback (most recent call last):
File "electrum/plugin.py", line 135, in load_plugin
spec.loader.exec_module(module)
File "<frozen importlib._bootstrap_external>", line 883, in exec_module
File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
File "/Users/vagrant/electrum/dist/Electrum.app/Contents/MacOS/electrum/plugins/trustedcoin/qt.py", line 51, in <module>
from .common_qt import TrustedcoinPluginQObject
File "/Users/vagrant/electrum/dist/Electrum.app/Contents/MacOS/electrum/plugins/trustedcoin/common_qt.py", line 16, in <module>
from electrum.gui.common_qt.plugins import PluginQObject
ModuleNotFoundError: No module named 'electrum.gui.common_qt'
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "run_electrum", line 456, in handle_cmd
d.run_gui()
File "electrum/daemon.py", line 617, in run_gui
self.gui_object = gui.ElectrumGui(config=self.config, daemon=self, plugins=self._plugins)
File "electrum/util.py", line 473, in do_profile
o = func(*args, **kw_args)
File "electrum/gui/qt/__init__.py", line 153, in __init__
self.plugins.load_plugin('trustedcoin')
File "electrum/plugin.py", line 138, in load_plugin
raise Exception(f"Error loading {name} plugin: {repr(e)}") from e
Exception: Error loading trustedcoin plugin: ModuleNotFoundError("No module named 'electrum.gui.common_qt'")
```
where the user has the preimage.
The CLTV requirements between old and new flow are imcompatible.
With the current locktime value, the server was vulnerable to an
attack where the client does not settle the lightning payment
and claims a refund. In order to support both old and new flows,
one would need to use different locktimes.
Note: the option to load a backup from SD card when the device already has a seed
has been removed. The device always returns an error when attempting this.
