Slasher (part 1)

[Rexagon]

This PR adds an initial slasher impl. It observes and analyzes blocks validation (a signature collection step after collation). It gives a rough idea of how well each node works. When vset changes each node analyzes each others reports and emits some metrics (stake punishment will be implemented in later PR's).

How does it work

Each validator collects BlocksBatches that contain a matrix of received signatures from other validator per each block.

These block batches are then sent to the Slasher Contract (message_ttl / message_retry_interval) and at the same time each validator parses all transactions from that contract. So each participant knows all block batches from everyone.

When vset changes an analyzer is triggered and all batches are reduced into a list of validator ids to accuse. For now, accusations are only visible on metric tycho_slasher_accusations_total{pubkey}.

Analyzer steps:

NOTE: It is executed independently by each participant with their local configs.

• It first checks that the validator set covers enough blocks and has enough validators (vset_len_threshold).
• Then it scans stored block batches and, for each observer, counts only blocks that reached the 2/3+1 weight threshold of valid signatures. Those blocks become the observer’s usable samples.
• For each observer, it measures how often every other validator produced valid signatures on those usable samples. It uses the median valid-signature rate as a baseline, scales it by slow_node_factor, and flags validators whose statistically adjusted upper-bound rate is still below that slow threshold. Accusation weights from observers are accumulated per each validator.
• A validator is considered as "indeed accused" if 2/3+1 observers (by weight) accused it, or if it produced too much malformed batches (malformed_samples_threshold).

Breaking Changes

Validators subset computation now uses a vset_switch_round from consensus_info.

Config Changes

A new section has been added:

{
  "slasher": {
    // TTL of messages to the slasher contract.
    "message_ttl": "30s",
    // Interval between message delivery attempts.
    "message_retry_interval": "1s",
    // Additional time to wait for the previous batch delivery.
    "prev_delivery_timeout": "5s",
    // Validator set round must contain at least this amount of blocks to run analyzer.
    "vset_len_threshold": 1000,
    // At least this number of block samples must be collected to accuse someone.
    "block_samples_threshold": 100,
    // At least this number of malformed batches must be collected to accuse someone.
    "malformed_samples_threshold": 5,
    // We treat the node as slow if its block rate is this times the median rate.
    "slow_node_factor": 0.5
  }
}

[github-actions]

🧪 Network Tests

To run network tests for this PR, use:

gh workflow run network-tests.yml -f pr_number=1098

Available test options:

• Run all tests: gh workflow run network-tests.yml -f pr_number=1098
• Run specific test: gh workflow run network-tests.yml -f pr_number=1098 -f test_selection=ping-pong

Test types: destroyable, ping-pong, one-to-many-internal-messages, fq-deploy, nft-index, persistent-sync

Results will be posted as workflow runs in the Actions tab.

[codecov]

Codecov Report

❌ Patch coverage is 33.06891% with 1350 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.67%. Comparing base (d41cb45) to head (70e67a7).

Files with missing lines	Patch %	Lines
slasher/src/lib.rs	0.00%	345 Missing ⚠️
slasher/src/collector/validator_events.rs	0.00%	202 Missing ⚠️
slasher/src/storage/mod.rs	0.00%	181 Missing ⚠️
slasher/src/analyzer.rs	0.00%	141 Missing ⚠️
slasher/src/bc/contract.rs	33.53%	108 Missing and 3 partials ⚠️
slasher/src/storage/models.rs	0.00%	93 Missing ⚠️
slasher/src/bc/mod.rs	30.69%	70 Missing ⚠️
slasher-traits/src/validator.rs	68.96%	53 Missing and 1 partial ⚠️
slasher/src/util.rs	79.90%	36 Missing and 6 partials ⚠️
slasher/src/storage/db.rs	0.00%	23 Missing ⚠️
... and 13 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1098      +/-   ##
==========================================
- Coverage   60.31%   59.67%   -0.65%     
==========================================
  Files         473      484      +11     
  Lines       80685    82583    +1898     
  Branches    80685    82583    +1898     
==========================================
+ Hits        48668    49279     +611     
- Misses      29692    30954    +1262     
- Partials     2325     2350      +25     

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