What the developer wrote
Authored by okaybro
Settle is_high_fee once in parse()
Both PSBTOverviewView and PSBTMathView asked the parser whether the fee was
high, and the overview asked twice (once for the screen, once for routing).
Each call re-summed the outputs through psbt.tx, which rebuilds the whole
transaction on every access. The totals it depends on are all fixed by the end
of parse(), so compute it there once and store it as is_high_fee, the same way
the other totals are exposed. has_high_fee() stays as the computation itself.
What changed, and why it matters
This commit is a performance cleanup, not a security fix. It calculates the 'is this fee unusually high?' flag once during transaction parsing instead of recalculating it every time a screen asks. The actual fee-checking logic and warning behavior are unchanged, so users still see the same high-fee warnings. The change just makes the device respond faster and avoids redundant work.
No security action needed. Treat as a normal performance/refactoring improvement. Reviewers may optionally verify that is_high_fee is always populated after parse() returns True and that no code path reads it before parse() is called.
Security signals we found
No security-relevant logic change: the same fee threshold and calculation are used
Performance optimization only: eliminates repeated transaction re-summation
No input validation, cryptography, or authorization changes
No mention of vulnerabilities, CVEs, or security disclosures in commit or diff
Evidence from the diff
The patch moves the high-fee determination from on-demand calls to has_high_fee() in PSBTOverviewView and PSBTMathView into a single computation at the end of PSBTParser.parse(), storing the result in self.is_high_fee. The has_high_fee() method remains unchanged as the underlying computation. Views now read the cached boolean. A test verifies that parse() sets the flag consistently with has_high_fee() for both low-fee and high-fee cases.
Changed components
src/seedsigner/models/psbt_parser.pysrc/seedsigner/views/psbt_views.pytests/test_psbt_parser.pyInspect captured patch +32 / −5
### src/seedsigner/models/psbt_parser.py
@@ -177,6 +177,11 @@ def __init__(self, p: PSBT, seed: Seed, network: str = SettingsConstants.MAINNET
self.destination_amounts = []
self.op_return_data: bytes = None
+ # Whether the fee is high relative to what is being sent; see has_high_fee().
+ # Computed once at the end of parse() so the views can read it without each
+ # re-walking the outputs.
+ self.is_high_fee: bool = False
+
# Contains one entry per input in psbt.inputs and per output in psbt.outputs. Each
# entry is either the derivation path the seed genuinely owns there, or it is set
# to `None`.
@@ -303,6 +308,9 @@ def parse(self):
if rt == False:
return False
+ # Every total is known now, so settle this once rather than per view.
+ self.is_high_fee = self.has_high_fee()
+
return True
### src/seedsigner/views/psbt_views.py
@@ -163,8 +163,6 @@ def run(self):
else:
num_self_transfer_outputs += 1
- is_high_fee_tx = psbt_parser.has_high_fee()
-
# Run the overview screen
selected_menu_num = self.run_screen(
PSBTOverviewScreen,
@@ -176,7 +174,7 @@ def run(self):
num_change_outputs=num_change_outputs,
destination_addresses=psbt_parser.destination_addresses,
has_op_return=psbt_parser.op_return_data is not None,
- is_high_fee_tx=is_high_fee_tx,
+ is_high_fee_tx=psbt_parser.is_high_fee,
)
if selected_menu_num == RET_CODE__BACK_BUTTON:
@@ -188,7 +186,7 @@ def run(self):
if psbt_parser.policy == None:
return Destination(PSBTUnsupportedScriptTypeWarningView)
- elif is_high_fee_tx:
+ elif psbt_parser.is_high_fee:
return Destination(PSBTHighFeeWarningView, view_args={"warning_threshold_percent": psbt_parser.HIGH_FEES_WARNING_THRESHOLD})
elif psbt_parser.change_amount == 0:
@@ -298,7 +296,7 @@ def run(self):
num_recipients=psbt_parser.num_destinations,
fee_amount=psbt_parser.fee_amount,
change_amount=psbt_parser.change_amount,
- is_high_fee_tx=psbt_parser.has_high_fee(),
+ is_high_fee_tx=psbt_parser.is_high_fee,
)
if selected_menu_num == RET_CODE__BACK_BUTTON:
### tests/test_psbt_parser.py
@@ -445,6 +445,27 @@ def test_has_high_fee(self, vin, vout_values, change_data, expected):
assert parser.has_high_fee() is expected
+ def test_parse_sets_is_high_fee(self):
+ """
+ parse() should settle is_high_fee once, from the real totals, so the views
+ can read it without recomputing. Checked in both directions: a realistic fee
+ leaves it False, a fee dwarfing the spend sets it True.
+ """
+ # 272 sat fee on a 2 BTC spend: nowhere near the threshold
+ psbt = PSBT.parse(a2b_base64(PSBTTestData.SINGLE_SIG_NATIVE_SEGWIT_2_INPUTS))
+ psbt_parser = PSBTParser(p=psbt, seed=PSBTTestData.two_input_seed, network=SettingsConstants.REGTEST)
+ assert psbt_parser.is_high_fee is False
+ assert psbt_parser.is_high_fee == psbt_parser.has_high_fee()
+
+ # 1 BTC input paying a 50,000 sat recipient and 10,000 sats change: almost all fee
+ psbt = PSBT.parse(a2b_base64(PSBTTestData.SINGLE_SIG_NATIVE_SEGWIT_1_INPUT))
+ psbt.outputs.append(create_output(PSBTTestData.SINGLE_SIG_NATIVE_SEGWIT_RECEIVE, 50_000))
+ psbt.outputs.append(create_output(PSBTTestData.SINGLE_SIG_NATIVE_SEGWIT_CHANGE, 10_000))
+ psbt_parser = PSBTParser(p=psbt, seed=PSBTTestData.seed, network=SettingsConstants.REGTEST)
+ assert psbt_parser.is_high_fee is True
+ assert psbt_parser.is_high_fee == psbt_parser.has_high_fee()
+
+
# TODO: Refactor all tests to be in the TestPSBTParser class(?)
def test_p2tr_change_detection():Why this scored 20/100
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