Also known as Ephemeral Dust.
We try to ensure that dust is spent in blocks by requiring:
- ephemeral dust tx is 0-fee
- ephemeral dust tx only has one dust output
- If the ephemeral dust transaction has a child,
the dust is spent by by that child.
0-fee requirement means there is no incentive to mine
a transaction which doesn't have a child bringing its
own fees for the transaction package.
The following scripted-diff commit will replace ParseHex("...") with "..."_hex_u8, but this replacement will not work in cases where vectors are needed instead of arrays, and is not ideal in cases where std::byte is accepted.
For example, it is currently necessary to use _hex_v_u8 when calling CScript operator<< because that operator does not currently support std::array or std::byte.
Conversely, it is incorrect to use _hex_v instead of _hex in net_processing.cpp for the MakeAndPushMessage argument, because if the argument is a std::vector it is considered variable-length and serialized with a size prefix, but if the argument is a std::array or Span is it considered fixed length and serialized without a prefix.
By the same logic, it is also safe to change the NUMS_H constant in pubkey.cpp from a std::vector to std::array because it is never serialized.
75648cea5a test: add P2A ProduceSignature coverage (Greg Sanders)
7998ce6b20 Add release note for P2A output feature (Greg Sanders)
71c9b02a04 test: add P2A coverage for decodescript (Greg Sanders)
1349e9ec15 test: Add anchor mempool acceptance test (Greg Sanders)
9d89209937 policy: stop 3rd party wtxid malleability of anchor spend (Greg Sanders)
b60aaf8b23 policy: make anchor spend standard (Greg Sanders)
455fca86cf policy: Add OP_1 <0x4e73> as a standard output type (Greg Sanders)
Pull request description:
This is a sub-feature taken out of the original proposal for ephemeral anchors #30239
This PR makes *spending* of `OP_1 <0x4e73>` (i.e. `bc1pfeessrawgf`) standard. Creation of this output type is already standard.
Any future witness output types are considered relay-standard to create, but not to spend. This preserves upgrade hooks, such as a completely new output type for a softfork such as BIP341. It also gives us a bit of room to use a new output type for policy uses.
This particular sized witness program has no other known use-cases (https://bitcoin.stackexchange.com/a/110664/17078), s it affords insufficient cryptographic security for a secure commitment to data, such as a script or a public key. This makes this type of output "keyless", or unauthenticated.
As a witness program, the `scriptSig` of the input MUST be blank, by BIP141. This helps ensure txid-stability of the spending transaction, which may be required for smart contracting wallets. If we do not use segwit, a miner can simply insert an `OP_NOP` in the `scriptSig` without effecting the result of program execution.
An additional relay restriction is to disallow non-empty witness data, which an adversary may use to penalize the "honest" transactor when RBF'ing the transaction due to the incremental fee requirement of RBF rules.
The intended use-case for this output type is to "anchor" the transaction with a spending child to bring exogenous CPFP fees into the transaction package, encouraging the inclusion of the package in a block. The minimal size of creation and spending of this output makes it an attractive contrast to outputs like `p2sh(OP_TRUE)` and `p2wsh(OP_TRUE)` which
are significantly larger in vbyte terms.
Combined with TRUC transactions which limits the size of child transactions significantly, this is an attractive option for presigned transactions that need to be fee-bumped after the fact.
ACKs for top commit:
sdaftuar:
utACK 75648cea5a
theStack:
re-ACK 75648cea5a
ismaelsadeeq:
re-ACK 75648cea5a via [diff](e7ce6dc070..75648cea5a)
glozow:
ACK 75648cea5a
tdb3:
ACK 75648cea5a
Tree-SHA512: d529de23d20857e6cdb40fa611d0446b49989eaafed06c28280e8fd1897f1ed8d89a4eabbec1bbf8df3d319910066c3dbbba5a70a87ff0b2967d5205db32ad1e
These outputs are called anchors, and allow
key-less anchor spends which are vsize-minimized
versus keyed anchors which require larger outputs
when creating and inputs when spending.
Prior to this, passing string_view::data() into uint256S() meant the latter would only receive the a naked char* pointer and potentially scan past the string_view::length() until it found a null terminator (or some other non-hex character).
Appears to have been a fully dormant bug as callers were either passing a string literal or std::string directly to TxidFromFromString(), meaning null terminator always existed at pointer[length()]. Bug existed since original merge of TxidFromString(), discussed in https://github.com/bitcoin/bitcoin/pull/28922#discussion_r1404437378.
Move its ownership to the ChainstateManager class.
Next to simplifying usage of the kernel library by no longer requiring
manual setup of the cache prior to using validation code, it also slims
down the amount of memory allocated by BasicTestingSetup.
Use this opportunity to make SignatureCache RAII styled
Co-authored-by: Ryan Ofsky <ryan@ofsky.org>
c7376babd1 doc: Clarify distinction between util and common libraries in libraries.md (Ryan Ofsky)
4f74c59334 util: Move util/string.h functions to util namespace (Ryan Ofsky)
4d05d3f3b4 util: add TransactionError includes and namespace declarations (Ryan Ofsky)
680eafdc74 util: move fees.h and error.h to common/messages.h (Ryan Ofsky)
02e62c6c9a common: Add PSBTError enum (Ryan Ofsky)
0d44c44ae3 util: move error.h TransactionError enum to node/types.h (Ryan Ofsky)
9bcce2608d util: move spanparsing.h to script/parsing.h (Ryan Ofsky)
6dd2ad4792 util: move spanparsing.h Split functions to string.h (Ryan Ofsky)
23cc8ddff4 util: move HexStr and HexDigit from util to crypto (TheCharlatan)
6861f954f8 util: move util/message to common/signmessage (Ryan Ofsky)
cc5f29fbea build: move memory_cleanse from util to crypto (Ryan Ofsky)
5b9309420c build: move chainparamsbase from util to common (Ryan Ofsky)
ffa27af24d test: Add check-deps.sh script to check for unexpected library dependencies (Ryan Ofsky)
Pull request description:
Remove `fees.h`, `errors.h`, and `spanparsing.h` from the util library. Specifically:
- Move `Split` functions from `util/spanparsing.h` to `util/string.h`, using `util` namespace for clarity.
- Move remaining spanparsing functions to `script/parsing.h` since they are used for descriptor and miniscript parsing.
- Combine `util/fees.h` and `util/errors.h` into `common/messages.h` so there is a place for simple functions that generate user messages to live, and these functions are not part of the util library.
Motivation for this change is that the util library is a dependency of the kernel, and we should remove functionality from util that shouldn't be called by kernel code or kernel applications. These changes should also improve code organization and make functions easier to discover. Some of these same moves are (or were) part of #28690, but did not help with code organization, or made it worse, so it is better to move them and clean them up in the same PR so code only has to change one time.
ACKs for top commit:
achow101:
ACK c7376babd1
TheCharlatan:
Re-ACK c7376babd1
hebasto:
re-ACK c7376babd1.
Tree-SHA512: 5bcef16c1255463b1b69270548711e7ff78ca0dd34e300b95e3ca1ce52ceb34f83d9ddb2839e83800ba36b200de30396e504bbb04fa02c6d0c24a16d06ae523d
429ec1aaaa refactor: Rename CTransaction::nVersion to version (Ava Chow)
27e70f1f5b consensus: Store transaction nVersion as uint32_t (Ava Chow)
Pull request description:
Given that the use of a transaction's nVersion is always as an unsigned int, it doesn't make sense to store it as signed and then cast it to unsigned everywhere it is used and displayed.
Since a few alternative implementations have recently been revealed to have made an error with this signedness that would have resulted in consensus failure, I think it makes sense for us to just make this always unsigned to make it clear that the version is treated as unsigned. This would also help us avoid future potential issues with signedness of this value.
I believe that this is safe and does not actually change what transactions would or would not be considered both standard and consensus valid. Within consensus, the only use of the version in consensus is in BIP68 validation which was already casting it to uint32_t. Within policy, although it is used as a signed int for the transaction version number check, I do not think that this change would change standardness. Standard transactions are limited to the range [1, 2]. Negative numbers would have fallen under the < 1 condition, but by making it unsigned, they are still non-standard under the > 2 condition.
Unsigned and signed ints are serialized and unserialized the same way so there is no change in serialization.
ACKs for top commit:
maflcko:
ACK 429ec1aaaa 🐿
glozow:
ACK 429ec1aaaa
shaavan:
ACK 429ec1aaaa💯
Tree-SHA512: 0bcd92a245d7d16c3665d2d4e815a4ef28207ad4a1fb46c6f0203cdafeab1b82c4e95e4bdce7805d80a4f4a46074f6542abad708e970550d38a00d759e3dcef1
