The weight unit is merely a consensus rule detail and is largely
irrelevant for fee-rate calculations and mempool policy rules (e.g. for
package relay and TRUC limits), so there doesn't seem to be any value of
using a granularity that we can't even guarantee to reach exactly
anyway.
Switch to the more natural unit of vsize instead, which simplifies both
the padding implementation and the current tests that take use of this
padding. The rather annoying multiplications by `WITNESS_SCALE_FACTOR`
can then be removed and weird-looking magic numbers like `4004` can be
replaced by numbers that are more connected to actual policy limit
constants from the codebase, e.g. `1001` for exceeding
`TRUC_CHILD_MAX_VSIZE` by one.
e4b0dabb21 test: add functional test for tagged MiniWallet instances (Sebastian Falbesoner)
3162c917e9 test: fix MiniWallet internal key derivation for tagged instances (Sebastian Falbesoner)
c9f7364ab2 test: fix MiniWallet script-path spend (missing parity bit in leaf version) (Sebastian Falbesoner)
7774c314fb test: refactor: return TaprootInfo from P2TR address creation routine (Sebastian Falbesoner)
Pull request description:
This PR fixes a dormant bug in MiniWallet that exists since support for P2TR was initially added in #23371 (see commit 041abfebe4).
In the course of spending the output, the leaf version byte of the control block in the witness stack doesn't set the parity bit, i.e. we were so far just lucky that the used combinations of relevant data (internal pubkey, leaf script / version) didn't result in a tweaked pubkey with odd y-parity. If that was the case, we'd get the following validation error:
`mandatory-script-verify-flag-failed (Witness program hash mismatch) (-26)`
Since MiniWallets can now optionally be tagged (#29939), resulting in different internal pubkeys, the issue is more prevalent now. Fix it by passing the parity bit, as specified in BIP341.
Can be tested with the following patch (fails on master, succeeds on PR):
```diff
diff --git a/test/functional/test_framework/mempool_util.py b/test/functional/test_framework/mempool_util.py
index 148cc935ed..7ebe858681 100644
--- a/test/functional/test_framework/mempool_util.py
+++ b/test/functional/test_framework/mempool_util.py
@@ -42,7 +42,7 @@ def fill_mempool(test_framework, node):
# Generate UTXOs to flood the mempool
# 1 to create a tx initially that will be evicted from the mempool later
# 75 transactions each with a fee rate higher than the previous one
- ephemeral_miniwallet = MiniWallet(node, tag_name="fill_mempool_ephemeral_wallet")
+ ephemeral_miniwallet = MiniWallet(node, tag_name="fill_mempool_ephemeral_wallet3")
test_framework.generate(ephemeral_miniwallet, 1 + num_of_batches * tx_batch_size)
# Mine enough blocks so that the UTXOs are allowed to be spent
```
In addition to that, another bug is fixed where the internal key derivation failed, as not every pseudorandom hash results in a valid x-only pubkey. Fix this by treating the hash result as private key and calculate the x-only public key out of that, to be used then as internal key.
Fixes#30528.
ACKs for top commit:
glozow:
ACK e4b0dabb21
rkrux:
reACK [e4b0dab](e4b0dabb21)
hodlinator:
ACK e4b0dabb21
Tree-SHA512: a16f33f76bcb1012857cc3129438a9f6badf28aa2b1d25696da0d385ba5866b46de0f1f93ba777ed9263fe6952f98d7d9c44ea0c0170a2bcc86cbef90bf6ac58
