This removes the ability to set an offset in the SpanReader constructor,
as the current code is broken. All call sites use pos=0, so it is actually
unused. If future call sites need it, SpanReader{a, b, c, d} is equivalent
to SpanReader{a, b, c.subspan(d)}.
It also removes the ability to deserialize from SpanReader directly from
the constructor. This too is unused, and can be more idiomatically
simulated using (SpanReader{a, b, c} >> x >> y >> z) instead of
SpanReader{a, b, c, x, y, z}.
11daf6ceb1 More Span simplifications (Pieter Wuille)
568dd2f839 Replace MakeSpan helper with Span deduction guide (Pieter Wuille)
Pull request description:
C++17 supports [user-defined deduction guides](https://en.cppreference.com/w/cpp/language/class_template_argument_deduction), allowing class constructors to be invoked without specifying class template arguments. Instead, the code can contain rules to infer the template arguments from the constructor argument types.
This alleviates the need for the `MakeSpan` helper. Convert the existing MakeSpan rules into deduction rules for `Span` itself, and replace all invocations of `MakeSpan` with just `Span` ones.
ACKs for top commit:
MarcoFalke:
re-ACK 11daf6ceb1 Only change is removing a hunk in the tests 🌕
Tree-SHA512: 10f3e82e4338f39d9b7b407cd11aac7ebe1e9191b58e3d7f4e5e338a4636c0e126b4a1d912127c7446f57ba356c8d6544482e47f97901efea6a54fffbfd7895f
725d7ae049 Use PrecomputedTransactionData in signet check (Pieter Wuille)
497718b467 Treat amount<0 also as missing data for P2WPKH/P2WSH (Pieter Wuille)
3820090bd6 Make all SignatureChecker explicit about missing data (Pieter Wuille)
b77b0cc507 Add MissingDataBehavior and make TransactionSignatureChecker handle it (Pieter Wuille)
Pull request description:
Currently we have 2 levels of potentially-missing data in the transaction signature hashes:
* P2WPKH/P2WSH hashes need the spent amount
* P2TR hashes need all spent outputs (amount + scriptPubKey)
Missing amounts are treated as -1 (thus leading to unexpected signature failures), while missing outputs in P2TR validation cause assertion failure. This is hard to extend for signing support, and also quite ugly in general.
In this PR, an explicit configuration option to {Mutable,}TransactionSignatureChecker is added (MissingDataBehavior enum class) to either select ASSERT_FAIL or FAIL. Validation code passes ASSERT_FAIL (as at validation time all data should always be passed, and anything else is a serious bug in the code), while signing code uses FAIL.
The existence of the ASSERT_FAIL option is really just an abundance of caution. Always using FAIL should be just fine, but if there were for some reason a code path in consensus code was introduced that misses certain data, I think we prefer as assertion failure over silently introducing a consensus change.
Potentially useful follow-ups (not for this PR, in my preference):
* Having an explicit script validation error code for missing data.
* Having a MissingDataBehavior::SUCCEED option as well, for use in script/sign.cpp DataFromTransaction (if a signature is present in a witness, and we don't have enough data to fully validate it, we should probably treat it as valid and not touch it).
ACKs for top commit:
sanket1729:
reACK 725d7ae049
Sjors:
ACK 725d7ae049
achow101:
re-ACK 725d7ae049
benthecarman:
ACK 725d7ae049
fjahr:
Code review ACK 725d7ae049
Tree-SHA512: d67dc51bae9ca7ef6eb9acccefd682529f397830f77d74cd305500a081ef55aede0e9fa380648c3a8dd4857aa7eeb1ab54fe808979d79db0784ac94ceb31b657
This is out of an abundance of caution only, as signet currently doesn't
enable taproot validation flags. Still, it seems cleaner to make sure
that all non-test code that passes MissingDataBehavior::ASSERT_FAIL
also actually makes sure no data can be missing.
Remove the implicit MissingDataBehavior::ASSERT_FAIL in the
*TransationSignatureChecker constructors, and instead specify
it explicit in all call sites:
* Test code uses ASSERT_FAIL
* Validation uses ASSERT_FAIL (through CachingTransactionSignatureChecker)
(including signet)
* libconsensus uses FAIL, matching the existing behavior of the
non-amount API (and the extended required data for taproot validation
is not available yet)
* Signing code uses FAIL
m_valid implies the block solution has been checked, which is not the
case. It only means the txs could be parsed. C++17 comes with
std::optional, so just use that instead.
