Refactor test to use abi decoder

Author: pazams

Diff for: index.js

@@ -2,6 +2,7 @@ const Web3 = require('web3');
 const ethUtil = require('ethereumjs-util');
 const ERC1271 = require('./ABIs/ERC1271');
 
+// bytes4(keccak256("isValidSignature(bytes32,bytes)")
 const ERC1271_MAGIC_VALUE = '0x1626ba7e';
 
 module.exports = class DappAuth {

Diff for: package.json

@@ -20,7 +20,9 @@
   "license": "MIT",
   "dependencies": {
     "ethereumjs-util": "^6.0.0",
-    "web3": "^1.0.0-beta.36"
+    "web3": "^1.0.0-beta.36",
+    "ethereumjs-abi": "^0.6.6",
+    "safe-buffer": "^5.1.2"
   },
   "devDependencies": {
     "babel-eslint": "^8.0.1",

Diff for: test/contract-mock.js

@@ -1,8 +1,10 @@
 const ethUtil = require('ethereumjs-util');
+const ethAbi = require('ethereumjs-abi');
+const Buffer = require('safe-buffer').Buffer;
 const utils = require('./utils');
 
-const erc725CoreInterfaceID = '0xd202158d';
-const erc725InterfaceID = '0xdc3d2a7b';
+// bytes4(keccak256("isValidSignature(bytes32,bytes)")
+const ERC1271_METHOD_SIG = '1626ba7e';
 
 module.exports = class MockContract {
   constructor(options) {
@@ -12,43 +14,42 @@ module.exports = class MockContract {
   }
 
   static _true() {
-    return '0x1626ba7e00000000000000000000000000000000000000000000000000000000';
+    return `0x${ERC1271_METHOD_SIG}00000000000000000000000000000000000000000000000000000000`; // a.k.a the "magic value".
   }
 
   static _false(callback) {
     return '0x0000000000000000000000000000000000000000000000000000000000000000';
   }
 
+  // @param {String} methodCall
+  // @param {String} methodParams
+  // @return {String}
   run(methodCall, methodParams) {
     switch (methodCall) {
-      case '1626ba7e':
-        const hash = `0x${methodParams.substring(0, 32 * 2)}`;
-        const signatureLength = parseInt(
-          methodParams.substring(95 * 2, 96 * 2),
-          16,
+      case ERC1271_METHOD_SIG:
+        const [hash, signature] = ethAbi.rawDecode(
+          ['bytes32', 'bytes'],
+          Buffer.from(methodParams, 'hex'),
         );
-        const signature = `0x${methodParams.substring(
-          96 * 2,
-          (96 + signatureLength) * 2,
-        )}`;
+
         return this._1626ba7e(hash, signature);
       default:
         throw new Error(`Unexpected method ${methodCall}`);
     }
   }
 
   // "isValidSignature" method call
+  // @param {Buffer} hash
+  // @param {Buffer} signature
+  // @return {String}
   _1626ba7e(hash, signature) {
     if (this.errorIsValidSignature) {
       throw new Error('isValidSignature call returned an error');
     }
 
     // Get the address of whoever signed this message
     const { v, r, s } = ethUtil.fromRpcSig(signature);
-    const erc191MessageHash = utils.erc191MessageHash(
-      ethUtil.toBuffer(hash),
-      this.address,
-    );
+    const erc191MessageHash = utils.erc191MessageHash(hash, this.address);
     const recoveredKey = ethUtil.ecrecover(erc191MessageHash, v, r, s);
     const recoveredAddress = ethUtil.publicToAddress(recoveredKey);
 

Diff for: yarn.lock

@@ -434,7 +434,7 @@ [email protected]:
   version "4.11.6"
   resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-4.11.6.tgz#53344adb14617a13f6e8dd2ce28905d1c0ba3215"
 
-bn.js@^4.0.0, bn.js@^4.1.0, bn.js@^4.1.1, bn.js@^4.11.0, bn.js@^4.11.3, bn.js@^4.11.6, bn.js@^4.4.0:
+bn.js@^4.0.0, bn.js@^4.1.0, bn.js@^4.1.1, bn.js@^4.10.0, bn.js@^4.11.0, bn.js@^4.11.3, bn.js@^4.11.6, bn.js@^4.4.0:
   version "4.11.8"
   resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-4.11.8.tgz#2cde09eb5ee341f484746bb0309b3253b1b1442f"
 
@@ -1296,6 +1296,27 @@ [email protected]:
     elliptic "^6.4.0"
     xhr-request-promise "^0.1.2"
 
+ethereumjs-abi@^0.6.6:
+  version "0.6.6"
+  resolved "https://registry.yarnpkg.com/ethereumjs-abi/-/ethereumjs-abi-0.6.6.tgz#f8ba3413a98478173f5a00f7f1316819db1d09ec"
+  integrity sha512-w8KubDsA/+OAuqtIR9RGsMcoZ5nhM8vxwjJAJvEIY+clhxA3BHoLG3+ClYQaQhD0n3mlDt3U5rBrmSVJvI3c8A==
+  dependencies:
+    bn.js "^4.10.0"
+    ethereumjs-util "^5.0.0"
+
+ethereumjs-util@^5.0.0:
+  version "5.2.0"
+  resolved "https://registry.yarnpkg.com/ethereumjs-util/-/ethereumjs-util-5.2.0.tgz#3e0c0d1741471acf1036052d048623dee54ad642"
+  integrity sha512-CJAKdI0wgMbQFLlLRtZKGcy/L6pzVRgelIZqRqNbuVFM3K9VEnyfbcvz0ncWMRNCe4kaHWjwRYQcYMucmwsnWA==
+  dependencies:
+    bn.js "^4.11.0"
+    create-hash "^1.1.2"
+    ethjs-util "^0.1.3"
+    keccak "^1.0.2"
+    rlp "^2.0.0"
+    safe-buffer "^5.1.1"
+    secp256k1 "^3.0.1"
+
 ethereumjs-util@^6.0.0:
   version "6.0.0"
   resolved "https://registry.yarnpkg.com/ethereumjs-util/-/ethereumjs-util-6.0.0.tgz#f14841c182b918615afefd744207c7932c8536c0"
@@ -1330,7 +1351,7 @@ [email protected]:
     bn.js "4.11.6"
     number-to-bn "1.7.0"
 
-ethjs-util@^0.1.6:
+ethjs-util@^0.1.3, ethjs-util@^0.1.6:
   version "0.1.6"
   resolved "https://registry.yarnpkg.com/ethjs-util/-/ethjs-util-0.1.6.tgz#f308b62f185f9fe6237132fb2a9818866a5cd536"
   dependencies: