accounts/abi/bind, eth: rely on getCode for sanity checks, not estimate and call

accounts/abi/bind/backends/nil.go

@@ -38,6 +38,7 @@ func (*nilBackend) ContractCall(common.Address, []byte, bool) ([]byte, error) {
 func (*nilBackend) EstimateGasLimit(common.Address, *common.Address, *big.Int, []byte) (*big.Int, error) {
 	panic("not implemented")
 }
+func (*nilBackend) HasCode(common.Address, bool) (bool, error)         { panic("not implemented") }
 func (*nilBackend) SuggestGasPrice() (*big.Int, error)                 { panic("not implemented") }
 func (*nilBackend) PendingAccountNonce(common.Address) (uint64, error) { panic("not implemented") }
 func (*nilBackend) SendTransaction(*types.Transaction) error           { panic("not implemented") }

accounts/abi/bind/backends/remote.go

@@ -111,6 +111,26 @@ func (b *rpcBackend) request(method string, params []interface{}) (json.RawMessa
 	return res.Result, nil
 }
 
+// HasCode implements ContractVerifier.HasCode by retrieving any code associated
+// with the contract from the remote node, and checking its size.
+func (b *rpcBackend) HasCode(contract common.Address, pending bool) (bool, error) {
+	// Execute the RPC code retrieval
+	block := "latest"
+	if pending {
+		block = "pending"
+	}
+	res, err := b.request("eth_getCode", []interface{}{contract.Hex(), block})
+	if err != nil {
+		return false, err
+	}
+	var hex string
+	if err := json.Unmarshal(res, &hex); err != nil {
+		return false, err
+	}
+	// Convert the response back to a Go byte slice and return
+	return len(common.FromHex(hex)) > 0, nil
+}
+
 // ContractCall implements ContractCaller.ContractCall, delegating the execution of
 // a contract call to the remote node, returning the reply to for local processing.
 func (b *rpcBackend) ContractCall(contract common.Address, data []byte, pending bool) ([]byte, error) {

accounts/abi/bind/backends/simulated.go

@@ -78,6 +78,16 @@ func (b *SimulatedBackend) Rollback() {
 	b.pendingState, _ = state.New(b.pendingBlock.Root(), b.database)
 }
 
+// HasCode implements ContractVerifier.HasCode, checking whether there is any
+// code associated with a certain account in the blockchain.
+func (b *SimulatedBackend) HasCode(contract common.Address, pending bool) (bool, error) {
+	if pending {
+		return len(b.pendingState.GetCode(contract)) > 0, nil
+	}
+	statedb, _ := b.blockchain.State()
+	return len(statedb.GetCode(contract)) > 0, nil
+}
+
 // ContractCall implements ContractCaller.ContractCall, executing the specified
 // contract with the given input data.
 func (b *SimulatedBackend) ContractCall(contract common.Address, data []byte, pending bool) ([]byte, error) {