feat: stateful precompiles #42
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@@ -50,3 +50,5 @@ profile.cov | |
| logs/ | ||
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| tests/spec-tests/ | ||
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| precompile/out/ | ||
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| Original file line number | Diff line number | Diff line change | ||||
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| @@ -0,0 +1,183 @@ | ||||||
| package vm | ||||||
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| import ( | ||||||
| "fmt" | ||||||
| "math/big" | ||||||
| "reflect" | ||||||
| "strings" | ||||||
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| "github.com/ethereum/go-ethereum/accounts/abi" | ||||||
| "github.com/ethereum/go-ethereum/common" | ||||||
| "github.com/ethereum/go-ethereum/precompile" | ||||||
| ) | ||||||
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| type methodID [4]byte | ||||||
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| type statefulMethod struct { | ||||||
| abiMethod abi.Method | ||||||
| reflectMethod reflect.Method | ||||||
| } | ||||||
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| type precompileMethods map[methodID]*statefulMethod | ||||||
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| type precompileManager struct { | ||||||
| evm *EVM | ||||||
| precompiles map[common.Address]precompile.StatefulPrecompiledContract | ||||||
| pMethods map[common.Address]precompileMethods | ||||||
| } | ||||||
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| func NewPrecompileManager(evm *EVM) PrecompileManager { | ||||||
| precompiles := make(map[common.Address]precompile.StatefulPrecompiledContract) | ||||||
| pMethods := make(map[common.Address]precompileMethods) | ||||||
| return &precompileManager{ | ||||||
| evm: evm, | ||||||
| precompiles: precompiles, | ||||||
| pMethods: pMethods, | ||||||
| } | ||||||
| } | ||||||
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| func (pm *precompileManager) IsPrecompile(addr common.Address) bool { | ||||||
| _, isEvmPrecompile := pm.evm.precompile(addr) | ||||||
| if isEvmPrecompile { | ||||||
| return true | ||||||
| } | ||||||
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| _, isStatefulPrecompile := pm.precompiles[addr] | ||||||
| return isStatefulPrecompile | ||||||
| } | ||||||
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| func (pm *precompileManager) Run( | ||||||
| addr common.Address, | ||||||
| input []byte, | ||||||
| caller common.Address, | ||||||
| value *big.Int, | ||||||
| suppliedGas uint64, | ||||||
| readOnly bool, | ||||||
| ) (ret []byte, remainingGas uint64, err error) { | ||||||
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| // run core evm precompile | ||||||
| p, isEvmPrecompile := pm.evm.precompile(addr) | ||||||
| if isEvmPrecompile { | ||||||
| return RunPrecompiledContract(p, input, suppliedGas) | ||||||
| } | ||||||
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| contract, ok := pm.precompiles[addr] | ||||||
| if !ok { | ||||||
| return nil, 0, fmt.Errorf("no precompiled contract at address %v", addr.Hex()) | ||||||
| } | ||||||
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| // Extract the method ID from the input | ||||||
| methodId := methodID(input) | ||||||
| // Try to get the method from the precompiled contracts using the method ID | ||||||
| method, exists := pm.pMethods[addr][methodId] | ||||||
| if !exists { | ||||||
| return nil, 0, fmt.Errorf("no method with id %v in precompiled contract at address %v", methodId, addr.Hex()) | ||||||
| } | ||||||
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| gasCost := contract.RequiredGas(input) | ||||||
| if gasCost > suppliedGas { | ||||||
| return nil, 0, ErrOutOfGas | ||||||
| } | ||||||
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| // Unpack the input arguments using the ABI method's inputs | ||||||
| unpackedArgs, err := method.abiMethod.Inputs.Unpack(input[4:]) | ||||||
| if err != nil { | ||||||
| return nil, 0, err | ||||||
| } | ||||||
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| // Convert the unpacked args to reflect values. | ||||||
| reflectedUnpackedArgs := make([]reflect.Value, 0, len(unpackedArgs)) | ||||||
| for _, unpacked := range unpackedArgs { | ||||||
| reflectedUnpackedArgs = append(reflectedUnpackedArgs, reflect.ValueOf(unpacked)) | ||||||
| } | ||||||
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| // set precompile nonce to 1 to avoid state deletion for being considered an empty account | ||||||
| // this conforms precompile contracts to EIP-161 | ||||||
| if pm.evm.StateDB.GetNonce(addr) == 0 { | ||||||
| pm.evm.StateDB.SetNonce(addr, 1) | ||||||
| } | ||||||
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| ctx := precompile.NewStatefulContext(pm.evm.StateDB, addr, caller, value) | ||||||
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| // Make sure the readOnly is only set if we aren't in readOnly yet. | ||||||
| // This also makes sure that the readOnly flag isn't removed for child calls. | ||||||
| if readOnly && !ctx.IsReadOnly() { | ||||||
| ctx.SetReadOnly(true) | ||||||
| defer func() { ctx.SetReadOnly(false) }() | ||||||
| } | ||||||
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| results := method.reflectMethod.Func.Call(append( | ||||||
| []reflect.Value{ | ||||||
| reflect.ValueOf(contract), | ||||||
| reflect.ValueOf(ctx), | ||||||
| }, | ||||||
| reflectedUnpackedArgs..., | ||||||
| )) | ||||||
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| // check if precompile returned an error | ||||||
| if len(results) > 0 { | ||||||
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There was a problem hiding this comment. can we check that the result parameters (length, type) are what are expected based on the method signature? |
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| if err, ok := results[len(results)-1].Interface().(error); ok && err != nil { | ||||||
| return nil, 0, err | ||||||
| } | ||||||
| } | ||||||
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| // Pack the result | ||||||
| var output []byte | ||||||
| if len(results) > 1 { | ||||||
| interfaceArgs := make([]interface{}, len(results)-1) | ||||||
| for i, v := range results[:len(results)-1] { | ||||||
| interfaceArgs[i] = v.Interface() | ||||||
| } | ||||||
| output, err = method.abiMethod.Outputs.Pack(interfaceArgs...) | ||||||
| if err != nil { | ||||||
| return nil, 0, err | ||||||
| } | ||||||
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Comment on lines
+131
to
+134
There was a problem hiding this comment. related to above - if the number/type of args aren't correct, this will probably error? |
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| } | ||||||
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| suppliedGas -= gasCost | ||||||
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There was a problem hiding this comment. does the caller check if this went negative? probably but just want to confirm There was a problem hiding this comment. There's a check above, Line 77, gasCost := contract.RequiredGas(input)
if gasCost > suppliedGas {
return nil, 0, ErrOutOfGas
} |
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| return output, suppliedGas, nil | ||||||
| } | ||||||
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| func (pm *precompileManager) Register(addr common.Address, p precompile.StatefulPrecompiledContract) error { | ||||||
| if _, isEvmPrecompile := pm.evm.precompile(addr); isEvmPrecompile { | ||||||
| return fmt.Errorf("precompiled contract already exists at address %v", addr.Hex()) | ||||||
| } | ||||||
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| if _, exists := pm.precompiles[addr]; exists { | ||||||
| return fmt.Errorf("precompiled contract already exists at address %v", addr.Hex()) | ||||||
| } | ||||||
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| // niaeve implementation; parsed abi method names must match precompile method names 1:1 | ||||||
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There was a problem hiding this comment.
Suggested change
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| // | ||||||
| // Note on method naming: | ||||||
| // Method name is the abi method name used for internal representation. It's derived from | ||||||
| // the abi raw name and a suffix will be added in the case of a function overload. | ||||||
| // | ||||||
| // e.g. | ||||||
| // These are two functions that have the same name: | ||||||
| // * foo(int,int) | ||||||
| // * foo(uint,uint) | ||||||
| // The method name of the first one will be resolved as Foo while the second one | ||||||
| // will be resolved as Foo0. | ||||||
| // | ||||||
| // Alternatively could require each precompile to define the func mapping instead of doing this magic | ||||||
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There was a problem hiding this comment. i think this is a lot better - the solidity/abigen stuff is unused apart from the abi, so we should remove it and just have the native code define the mapping. |
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| abiMethods := p.GetABI().Methods | ||||||
| contractType := reflect.ValueOf(p).Type() | ||||||
| precompileMethods := make(precompileMethods) | ||||||
| for _, abiMethod := range abiMethods { | ||||||
| mName := strings.ToUpper(string(abiMethod.Name[0])) + abiMethod.Name[1:] | ||||||
| reflectMethod, exists := contractType.MethodByName(mName) | ||||||
| if !exists { | ||||||
| return fmt.Errorf("precompiled contract does not implement abi method %s with signature %s", abiMethod.Name, abiMethod.RawName) | ||||||
| } | ||||||
| mID := methodID(abiMethod.ID) | ||||||
| precompileMethods[mID] = &statefulMethod{ | ||||||
| abiMethod: abiMethod, | ||||||
| reflectMethod: reflectMethod, | ||||||
| } | ||||||
| } | ||||||
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| pm.precompiles[addr] = p | ||||||
| pm.pMethods[addr] = precompileMethods | ||||||
| return nil | ||||||
| } | ||||||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,9 @@ | ||
| # Writing a Precompile Contract | ||
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| 1. Create Solidity interface in `contracts/interfaces`, e.g, IExampleContract.sol | ||
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| 2. Generate bindings with `./gen.sh` | ||
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| 3. Implement the precompile in Go. The struct should implement the `StatefulPrecompiledContract` interface and methods defined in the Solidity interface. | ||
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| See NativeMinter as an example implementation |
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do we want to have this functionality here? probably would be better to move to an example branch
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No, it def needs removed, at least registering one. Could probably just be moved to a precompile doc that explains a bit and shows examples