With this new method, outputs to an arbitrary scriptPubKey/amount can
be created. Note that the implementation was already present in the
test feature_rbf.py and is just moved to the MiniWallet interface, in
order to enable other tests to also use it.
f680d27155 test: use MiniWallet for make_utxo helper in feature_rbf.py (Sebastian Falbesoner)
0f27524602 test: scale amounts in test_doublespend_tree down by factor 10 (Sebastian Falbesoner)
d1e2481274 test: scale amounts in test_doublespend_chain down by factor 10 (Sebastian Falbesoner)
Pull request description:
This PR aims to further increase MiniWallet usage in the functional test feature_rbf.py by using it in the `make_utxo(...)` helper, which is the only part that needs a wallet for most sub-tests. In order to do that, the amounts for the utxos have to be scaled down in two sub-tests first (`test_doublespend_chain` and `test_doublespend_tree`, see first two commits), since we need amounts passed to `make_utxo` than can be funded by only one input. For creating UTXOs with a value of 50 BTC, we'd need to implement a method for consolidating multiple utxos into one first, which seems to be overkill.
Note that after this PR's change, there is only one sub-test left (`test_rpc`) that needs the wallet compiled into bitcoind.
ACKs for top commit:
MarcoFalke:
review ACK f680d27155🦐
Tree-SHA512: 46c8c245086a9e79855c4ede2f8f412333cf2658136805196b203b3567c89398d77fcb80715c0bb72fdc84331cc67544b2fdc259193a3adcb2fc36e147c26fce
d6d2ab9845 test: MiniWallet: fix fee calculation for P2PK and check tx vsize (Sebastian Falbesoner)
ce024b1c0e test: MiniWallet: force P2PK signature to have fixed size (71 bytes) (Sebastian Falbesoner)
Pull request description:
This PR is a follow-up to #21945. It aims to both fix the fee calculation for P2PK mode transactions and enable its vsize check. Currently, the latter assumes a fixed tx length, which is fine for anyone-can-spend txs but doesn't apply to P2PK output spends due to varying DER signature size; the vsize check is therefore disabled for P2PK mode on master branch.
Creating one million DER signatures with MiniWallet shows the following distribution of sizes (smart people with better math skills probably could deduce the ratios without trying, but hey):
| DER signature size [bytes] | #occurences (ratio) |
| ------------- | ------------- |
| 71 | 498893 (49.89%) |
| 70 | 497244 (49.72%) |
| 69 | 3837 (0.38%) |
| 68 | 22 (0.0022%) |
Note that even smaller signatures are possible (for smaller R and S values with leading zero bytes), it's just that the probability decreases exponentially. Instead of choosing a large vsize check range and hoping that smaller signatures are never created (potentially leading to flaky tests), the proposed solution is ~~to limit the signature size to the two most common sizes 71 and 70 (>99.6% probability) and then accordingly only check for two vsize values; the value to be used for fee calculation is a decimal right between the two possible sizes (167.5 vbytes) and for the vsize check it's rounded down/up integer values are used.~~ to simply grind the signature to a fixed size of 71 bytes (49.89% probability, i.e. on average each call to `sign_tx()`, on average two ECC signing operations are needed).
~~The idea of grinding signatures to a fixed size (similar to https://github.com/bitcoin/bitcoin/pull/13666 which grinds to low-R values) would be counter-productive, as the signature creation in the test suite is quite expensive and this would significantly slow down tests that calculate hundreds of signatures (like e.g. feature_csv_activation.py).~~
For more about transaction sizes on different input/output types, see the following interesting article: https://medium.com/coinmonks/on-bitcoin-transaction-sizes-97e31bc9d816
ACKs for top commit:
MarcoFalke:
Concept ACK d6d2ab9845
Tree-SHA512: 011c70ee0e4adf9ba12902e4b6c411db9ae96bdd8bc810bf1d67713367998e28ea328394503371fc1f5087a819547ddaea56c073b28db893ae1c0031d7927f32
In order to enable exact fee calculation for transactions that spend
P2PK outputs in the MiniWallet, we enforce the created signatures to
have a fixed length (>49.89% probability) by default. With that it is
easier to check the created transactions vsize and avoid flaky tests
that would appear whenever the signatures R- or S-values are smaller
(due to leading zero bytes).
Note that to get the total scriptSig size one has to add another
2 bytes, as there is also the OP_PUSHx instruction on the front and
the sighash type byte on the back, leading to a final scriptSig size
of 73 bytes.
- run mempool_reorg.py even when the wallet is not compiled
- add `locktime` argument to `create_self_transfer` and `send_self_transfer`
- use more logs instead of comments
For the MiniWallet constructor, the two boolean parameters
"raw_script" and "use_p2pk" are replaced by a single parameter of the
newly introduced type MiniWalletMode (derived by enum.Enum), which can
hold the following values:
- ADDRESS_OP_TRUE
- RAW_OP_TRUE
- RAW_P2PK
Adds two new features to MiniWallet:
* The fee rate is irrelevant sometimes, so just set an arbitrary default
* The utxo to spend needs to be selected manually sometimes
