l2geth: fix eth call evm context (#632)

* l2geth: correct timestamp + blocknumber in eth_call

* test: correct eth_call blocknumber + timestamp

* chore: add changeset

.changeset/old-mirrors-doubt.md

+---
+"@eth-optimism/integration-tests": patch
+"@eth-optimism/l2geth": patch
+---
+
+Correctly set the OVM context based on the L1 values during `eth_call`. This will also set it during `eth_estimateGas`. Add tests for this in the integration tests

integration-tests/test/ovmcontext.spec.ts

@@ -99,6 +99,32 @@ describe('OVM Context: Layer 2 EVM Context', () => {
     }
   })
 
+  it('should set correct OVM Context for `eth_call`', async () => {
+    const tip = await L2Provider.getBlockWithTransactions('latest')
+    const start = Math.max(0, tip.number - 5)
+
+    for (let i = start; i < tip.number; i++) {
+      const block = await L2Provider.getBlockWithTransactions(i)
+      const [, returnData] = await OVMMulticall.callStatic.aggregate([
+        [
+          OVMMulticall.address,
+          OVMMulticall.interface.encodeFunctionData('getCurrentBlockTimestamp'),
+        ],
+        [
+          OVMMulticall.address,
+          OVMMulticall.interface.encodeFunctionData('getCurrentBlockNumber'),
+        ],
+      ], {blockTag: i})
+
+      const timestamp = BigNumber.from(returnData[0])
+      const blockNumber = BigNumber.from(returnData[1])
+      const tx = block.transactions[0] as any
+
+      expect(tx.l1BlockNumber).to.deep.equal(blockNumber.toNumber())
+      expect(block.timestamp).to.deep.equal(timestamp.toNumber())
+    }
+  })
+
   /**
    * `rollup_getInfo` is a new RPC endpoint that is used to return the OVM
    * context. The data returned should match what is actually being used as the
@@ -126,8 +152,7 @@ describe('OVM Context: Layer 2 EVM Context', () => {
     const timestamp = BigNumber.from(returnData[0])
     const blockNumber = BigNumber.from(returnData[1])
 
-    // TODO: this is a bug and needs to be fixed
-    //expect(info.ethContext.blockNumber).to.deep.equal(blockNumber.toNumber())
+    expect(info.ethContext.blockNumber).to.deep.equal(blockNumber.toNumber())
     expect(info.ethContext.timestamp).to.deep.equal(timestamp.toNumber())
   })
 })

l2geth/core/state_transition_ovm.go

@@ -103,7 +103,7 @@ func EncodeSimulatedMessage(msg Message, timestamp, blockNumber *big.Int, execut
 
 	tx := ovmTransaction{
 		timestamp,
-		blockNumber, // TODO (what's the correct block number?)
+		blockNumber,
 		uint8(msg.QueueOrigin().Uint64()),
 		*msg.L1MessageSender(),
 		*to,

l2geth/internal/ethapi/api.go

@@ -923,6 +923,9 @@ func DoCall(ctx context.Context, b Backend, args CallArgs, blockNrOrHash rpc.Blo
 		data = []byte(*args.Data)
 	}
 
+	blockNumber := header.Number
+	timestamp := new(big.Int).SetUint64(header.Time)
+
 	// Create new call message
 	var msg core.Message
 	msg = types.NewMessage(addr, args.To, 0, value, gas, gasPrice, data, false, &addr, nil, types.QueueOriginSequencer, 0)
@@ -930,9 +933,19 @@ func DoCall(ctx context.Context, b Backend, args CallArgs, blockNrOrHash rpc.Blo
 		cfg := b.ChainConfig()
 		executionManager := cfg.StateDump.Accounts["OVM_ExecutionManager"]
 		stateManager := cfg.StateDump.Accounts["OVM_StateManager"]
-		var err error
-		blockNumber := header.Number
-		timestamp := new(big.Int).SetUint64(header.Time)
+		block, err := b.BlockByNumber(ctx, rpc.BlockNumber(header.Number.Uint64()))
+		if err != nil {
+			return nil, 0, false, err
+		}
+		txs := block.Transactions()
+		if header.Number.Uint64() != 0 {
+			if len(txs) != 1 {
+				return nil, 0, false, fmt.Errorf("block %d has more than 1 transaction", header.Number.Uint64())
+			}
+			tx := txs[0]
+			blockNumber = tx.L1BlockNumber()
+			timestamp = new(big.Int).SetUint64(tx.L1Timestamp())
+		}
 		msg, err = core.EncodeSimulatedMessage(msg, timestamp, blockNumber, executionManager, stateManager)
 		if err != nil {
 			return nil, 0, false, err
@@ -968,6 +981,8 @@ func DoCall(ctx context.Context, b Backend, args CallArgs, blockNrOrHash rpc.Blo
 	gp := new(core.GasPool).AddGas(math.MaxUint64)
 	if vm.UsingOVM {
 		evm.Context.EthCallSender = &addr
+		evm.Context.BlockNumber = blockNumber
+		evm.Context.Time = timestamp
 	}
 	res, gas, failed, err := core.ApplyMessage(evm, msg, gp)
 	if err := vmError(); err != nil {