a18e572328 test: more template verification tests (Sjors Provoost)
10c908808f test: move gbt proposal mode tests to new file (Sjors Provoost)
94959b8dee Add checkBlock to Mining interface (Sjors Provoost)
6077157531 ipc: drop BlockValidationState special handling (Sjors Provoost)
74690f4ed8 validation: refactor TestBlockValidity (Sjors Provoost)
Pull request description:
This PR adds the IPC equivalent of the `getblocktemplate` RPC in `proposal` mode.
In order to do so it has `TestBlockValidity` return error reasons as a string instead of `BlockValidationState`. This avoids complexity in IPC code for handling the latter struct.
The new Mining interface method is used in `miner_tests`.
It's not used by the `getblocktemplate` and `generateblock` RPC calls, see https://github.com/bitcoin/bitcoin/pull/31981#discussion_r2096473337
The `inconclusive-not-best-prevblk` check is moved from RPC
code to `TestBlockValidity`.
Test coverage is increased by `mining_template_verification.py`.
Superseedes #31564
## Background
### Verifying block templates (no PoW)
Stratum v2 allows miners to generate their own block template. Pools may wish (or need) to verify these templates. This typically involves comparing mempools, asking miners to providing missing transactions and then reconstructing the proposed block.[^0] This is not sufficient to ensure a proposed block is actually valid. In some schemes miners could take advantage of incomplete validation[^1].
The Stratum Reference Implementation (SRI), currently the only Stratum v2 implementation, collects all missing mempool transactions, but does not yet fully verify the block.[^2]. It could use the `getblocktemplate` RPC in `proposal` mode, but using IPC is more performant, as it avoids serialising up to 4 MB of transaction data as JSON.
(although SRI could use this PR, the Template Provider role doesn't need it, so this is _not_ part of #31098)
[^0]: https://github.com/stratum-mining/sv2-spec/blob/main/06-Job-Declaration-Protocol.md
[^1]: https://delvingbitcoin.org/t/pplns-with-job-declaration/1099/45?u=sjors
[^2]: https://github.com/stratum-mining/stratum/blob/v1.1.0/roles/jd-server/src/lib/job_declarator/message_handler.rs#L196
ACKs for top commit:
davidgumberg:
reACK a18e572328
achow101:
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TheCharlatan:
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ryanofsky:
Code review ACK a18e572328 just adding another NONFATAL_UNREACHABLE since last review
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9a7eece5a4