EIP-7002: Validator Exit contract helper and adding exits to created blocks #6883

lucassaldanha · 2024-04-04T21:09:30Z

Sorry for the big PR! I tried to keep it more concise but lots of the pieces kinda work together so it was hard to separate them! Hopefully, it isn't too bad to review as a bulk of the changes are adding a parameter to a constructor or something like that... ❤️

This is an experimental implementation of EIP-7002 logic for adding exits from the Validator Exit smart contract into blocks (and including them on the execution payload object of the Engine API).

Summary of changes

Updated engine API method and ExecutionPayload structure to support exits
Implemented Validator Exit Contract Helper (contract storage manipulation)
Updated BlockCreator to include exits from the validator exit contract

fixes #6881 and #6882

Open Questions/Future Improvements

Do we need extra validation on AbstractBlockProcessor (e.g. check that we do not have more exits than expected). I have a feeling we do not need to as we are running the system logic as part of processing, so any difference between the exits in the block we are validating would be caught by a different exits_root post our processing. But I might be wrong. The same question applies to MainnetBlockBodyValidator. validateBodyLight().
The Validator Exits contract address might need to be parameterized for each network. The same applies to things like the maximum number of exits per block, etc.
Do we need to have ValidatorExitContractHelper behind a protocol schedule setup in case the contract goes through some changes in future upgrades?
We need to properly implement a system call to the Validator Exit contract, replacing the exiting contract storage manipulation in the Validator Exit Contract Helper. EIP-7002: Implement Validator Exit Contract system call #6918

Engine API changes

Most of the logic was already there, few pieces had to be added (e.g. constructor parameters but the core of the logic hasn't changed). The more important change is how GetPayloadV4 includes the exits in the execution payload.

Validator Exit Contract Helper

This is an initial implementation based on the work done by lightclient on the Validator Exit smart contract (https://github.com/lightclient/7002asm), and also using the bytecode defined in the EIP (https://eips.ethereum.org/EIPS/eip-7002#deployment).

Each exit uses 3 storage slots (each slot has 32 bytes). There is a bit of trickery to ensure they fit in exactly on 3 slots (some right/left padding depending on the field). The detailed diagram of the expected storage can be seen in this code.

UPDATE: contract manipulation is not the best way of implementing this. The smart contract actually has all the logic to handle the system call. All we need to do is implement the mechanism to perform "send a tx" from the system account. I believe we do not have this logic in Besu at the moment, the closest thing I can think of is how we use a fake transaction in the TransactionSimulator, but we would need a way of ensuring that changes in contract storage are persisted. See #6918

Including exits on blocks

The system call logic has been implemented in a way that manipulates the contract storage as if we were executing the call through the EVM (although no EVM is involved). ~~This seems to be the expected behaviour for system calls.~~ The heart of this is how AbstractBlockCreator uses ValidatorExitContractHelper.popExitsFromQueue(..).

…tion payload for engineV4 methods Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

…ocks Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Gabriel-Trintinalia

Nice testing, PR looks good. I have added some comments.

Gabriel-Trintinalia · 2024-04-10T20:39:00Z

...reum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/MainnetBlockBodyValidator.java

+      if (!validateExits(block, body.getExits().get())) {
+        return false;
+      }


Nit:

Suggested change

if (!validateExits(block, body.getExits().get())) {

return false;

}

return validateExits(block, body.getExits().get());

Gabriel-Trintinalia · 2024-04-10T20:56:39Z

...um/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/ValidatorExitContractHelper.java

+/**
+ * Helper for interacting with the Validator Exit Contract (https://eips.ethereum.org/EIPS/eip-7002)
+ *
+ * <p>Please note that this is not the spec-way of interacting with the Validator Exit contract. See
+ * https://github.com/hyperledger/besu/issues/6918 for more information.
+ */


Suggested change

/**

* Helper for interacting with the Validator Exit Contract (https://eips.ethereum.org/EIPS/eip-7002)

*

* <p>Please note that this is not the spec-way of interacting with the Validator Exit contract. See

* https://github.com/hyperledger/besu/issues/6918 for more information.

*/

/**

* Helper for interacting with the Validator Exit Contract (<a

* href="https://eips.ethereum.org/EIPS/eip-7002">eip-7002</a>)

*

* <p>TODO: Please note that this is not the spec-way of interacting with the Validator Exit

* contract. See <a href="https://github.com/hyperledger/besu/issues/6918">#6918</a> for more

* information.

*/

Gabriel-Trintinalia · 2024-04-10T21:03:07Z

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/ValidatorExitsValidator.java

+      }
+
+      final List<ValidatorExit> exitsInBlock = block.getBody().getExits().get();
+      // TODO Do we need to allow for customization? (e.g. if the value changes in the next fork)


Suggestion: We could rename it to PrageExitsValidator, and make it a standalone class. If the next fork needs to change this we can easily abstract a class override what we need.

nit: Also, giving the validations, the semantics here are more like a RequiredExitsValidator than an AllowedExistsValidator.

Gabriel-Trintinalia · 2024-04-10T21:11:51Z

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/AbstractBlockProcessor.java

@@ -197,6 +197,12 @@ public BlockProcessingResult processBlock(
      }
    }

+    final ValidatorExitsValidator exitsValidator = protocolSpec.getExitsValidator();
+    if (exitsValidator instanceof ValidatorExitsValidator.AllowedExits) {


I think that the verification to perform the popping should belong to the validator/processor itself and not the blockprocessor. Maybe an extra method allowExists()?

Gabriel-Trintinalia · 2024-04-11T01:55:29Z

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/ValidatorExitsValidator.java

+      if (block.getHeader().getExitsRoot().isEmpty()) {
+        LOG.warn("Block {} must contain exits_root", blockHash);
+        return false;
+      }


This piece should be probably in a headervalidationrules instead of here

Gabriel-Trintinalia · 2024-04-11T01:55:50Z

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/ValidatorExitsValidator.java

+      final Hash expectedExitsRoot = BodyValidation.exitsRoot(exitsInBlock);
+      if (!expectedExitsRoot.equals(block.getHeader().getExitsRoot().get())) {
+        LOG.warn(
+            "Block {} exits_root does not match expected hash root for exits in block", blockHash);
+        return false;
+      }


Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Gabriel-Trintinalia

LGTM

…blocks (hyperledger#6883) Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com> Signed-off-by: Antonio Mota <antonio.mota@citi.com>

…blocks (hyperledger#6883) Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

lucassaldanha force-pushed the eip-7002-with-precompile branch 2 times, most recently from ced776d to 53758f0 Compare April 4, 2024 21:35

lucassaldanha changed the title ~~Implemented Validator Exit contract helper~~ EIP-7002: Validator Exit contract helper and adding exits to created blocks Apr 4, 2024

lucassaldanha added 18 commits April 9, 2024 20:18

EIP-7002: Add exits/exits_root to block/block_header and update execu…

90e0663

…tion payload for engineV4 methods Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Pending changes

38bb7b6

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Fix BlockHeaderTestFixture

d1e968f

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Remove 7002 precompile entry

f926dc1

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Validator exit contract helper

042a82b

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

ValidatorExitsValidator tests

ca655ed

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Fix ValidatorExit toString()

fd59512

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Adding exits to created blocks and processing exits when importing bl…

e4862cf

…ocks Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Fix missing headers

72ba1ce

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Added comment

2898221

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Spotless

2baaa30

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Fix padding on validtor exit contract storage

3099641

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Fixing tests after updating padding

4691ffa

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Refactor variable name

6d442ca

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Removing comment

fa473d5

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Spotless

a9c3620

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Updated AT flow

ea3d4eb

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Including block body validation for exits

7e80b83

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

lucassaldanha force-pushed the eip-7002-with-precompile branch from 24d400a to 7e80b83 Compare April 9, 2024 10:52

Updated comment

3c40529

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

lucassaldanha marked this pull request as ready for review April 9, 2024 11:05

Gabriel-Trintinalia reviewed Apr 10, 2024

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Gabriel-Trintinalia reviewed Apr 11, 2024

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lucassaldanha added 4 commits April 15, 2024 10:45

Merge branch 'main' into eip-7002-with-precompile

bb06b37

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Refactoging ValidatorExitsValidator

2d4b717

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

add license header

00130b4

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

add license header

f08cb01

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

lucassaldanha added 3 commits April 16, 2024 21:27

fix unit test

af40d6b

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Merge branch 'main' into eip-7002-with-precompile

e98a049

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Fix another mock

3d0c464

Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

Gabriel-Trintinalia approved these changes Apr 17, 2024

View reviewed changes

Merge branch 'main' into eip-7002-with-precompile

7c40e49

lucassaldanha enabled auto-merge (squash) April 17, 2024 20:31

lucassaldanha merged commit 6143283 into hyperledger:main Apr 17, 2024
42 checks passed

lucassaldanha deleted the eip-7002-with-precompile branch April 17, 2024 21:00

macfarla pushed a commit to macfarla/besu that referenced this pull request Apr 26, 2024

EIP-7002: Validator Exit contract helper and adding exits to created …

79480d7

…blocks (hyperledger#6883) Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

matthew1001 pushed a commit to kaleido-io/besu that referenced this pull request Jun 7, 2024

EIP-7002: Validator Exit contract helper and adding exits to created …

b51be86

…blocks (hyperledger#6883) Signed-off-by: Lucas Saldanha <lucascrsaldanha@gmail.com>

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EIP-7002: Validator Exit contract helper and adding exits to created blocks #6883

EIP-7002: Validator Exit contract helper and adding exits to created blocks #6883

lucassaldanha commented Apr 4, 2024 •

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-/**
- * Helper for interacting with the Validator Exit Contract (https://eips.ethereum.org/EIPS/eip-7002)
- *
- * <p>Please note that this is not the spec-way of interacting with the Validator Exit contract. See
- * https://github.com/hyperledger/besu/issues/6918 for more information.
- */
+/**
+ * Helper for interacting with the Validator Exit Contract (<a
+ * href="https://eips.ethereum.org/EIPS/eip-7002">eip-7002</a>)
+ *
+ * <p>TODO: Please note that this is not the spec-way of interacting with the Validator Exit
+ * contract. See <a href="https://github.com/hyperledger/besu/issues/6918">#6918</a> for more
+ * information.
+ */

EIP-7002: Validator Exit contract helper and adding exits to created blocks #6883

EIP-7002: Validator Exit contract helper and adding exits to created blocks #6883

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lucassaldanha commented Apr 4, 2024 • edited Loading

Engine API changes

Validator Exit Contract Helper

Including exits on blocks

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lucassaldanha commented Apr 4, 2024 •

edited

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