use ethers abi parser to validate function abi

src/conditions/base/contract.ts

@@ -1,3 +1,4 @@
+import { ethers } from 'ethers';
 import Joi from 'joi';
 
 import { ETH_ADDRESS_REGEXP } from '../const';
@@ -6,38 +7,76 @@ import { RpcCondition, rpcConditionSchema } from './rpc';
 
 export const STANDARD_CONTRACT_TYPES = ['ERC20', 'ERC721'];
 
-const functionAbiVariable = Joi.object({
- internalType: Joi.string().required(),
- name: Joi.string().required(),
- type: Joi.string().required(),
-});
-
-const functionAbiSchema = Joi.object({
- name: Joi.string().required(),
- type: Joi.string().valid('function').required(),
- inputs: Joi.array().items(functionAbiVariable),
- outputs: Joi.array().items(functionAbiVariable),
- // TODO: Should we restrict this to 'view'?
- // stateMutability: Joi.string().valid('view').required(),
-}).custom((functionAbi, helper) => {
- // Validate method name
- const method = helper.state.ancestors[0].method;
- if (functionAbi.name !== method) {
- return helper.message({
- custom: '"method" must be the same as "functionAbi.name"',
- });
- }
-
- // Validate nr of parameters
- const parameters = helper.state.ancestors[0].parameters;
- if (functionAbi.inputs?.length !== parameters.length) {
- return helper.message({
- custom: '"parameters" must have the same length as "functionAbi.inputs"',
- });
- }
-
- return functionAbi;
-});
+const functionAbiSchema = Joi
+ .object
+ // We can either define a schema here and use it in the custom validator below,
+ // {
+ // name: Joi.string().required(),
+ // type: Joi.string().valid('function').required(),
+ // inputs: Joi.array(),
+ // outputs: Joi.array(),
+ // stateMutability: Joi.string().valid('view', 'pure').required(),
+ // }
+ // Or rely on the fact that the ethers.js interface will throw if the ABI is invalid
+ // But then we also need to make few checks ourselves
+ ()
+ .custom((functionAbi, helper) => {
+ // Validate function ABI - Can we parse it?
+ let asInterface;
+ try {
+ asInterface = new ethers.utils.Interface([functionAbi]);
+ } catch (e: unknown) {
+ const { message } = e as Error;
+ return helper.message({
+ custom: message,
+ });
+ }
+
+ if (!asInterface.fragments) {
+ return helper.message({
+ custom: '"functionAbi" is missing a function fragment',
+ });
+ }
+
+ if (asInterface.fragments.length > 1) {
+ return helper.message({
+ custom: '"functionAbi" must contain exactly one function fragment',
+ });
+ }
+
+ // Now we just need to validate against the parent schema
+
+ // Validate method name
+ const method = helper.state.ancestors[0].method;
+ const functionFragment = asInterface.fragments.filter(
+ (f) => f.name === method
+ )[0];
+ if (!functionFragment) {
+ return helper.message({
+ custom:
+ '"functionAbi" does not contain the method specified as "method"',
+ });
+ }
+
+ // Validate nr of parameters
+ const parameters = helper.state.ancestors[0].parameters;
+ if (functionFragment.inputs.length !== parameters.length) {
+ return helper.message({
+ custom:
+ '"parameters" must have the same length as "functionAbi.inputs"',
+ });
+ }
+
+ // Further validate contents of the function
+ // TODO: functionFragment.stateMutability is not accessible for some reason
+ // if (["view", "pure"].includes(functionFragment.stateMutability)) {
+ // return helper.message({
+ // custom: '"functionAbi" must be a view or pure function',
+ // });
+ // }
+
+ return functionAbi;
+ });
 
 const contractMethodSchemas: Record<string, Joi.Schema> = {
  ...rpcConditionSchema,

test/unit/testVariables.ts

@@ -38,6 +38,7 @@ export const testContractConditionObj = {
 export const testFunctionAbi = {
  name: 'myFunction',
  type: 'function',
+ stateMutability: 'view',
  inputs: [
  {
  internalType: 'address',