Add schema validation and assertion, create ECSignature schema

package.json

@@ -33,6 +33,7 @@
   "devDependencies": {
     "@types/bignumber.js": "^4.0.2",
     "@types/chai": "^3.5.2",
+    "@types/jsonschema": "^1.1.1",
     "@types/mocha": "^2.2.41",
     "@types/node": "^7.0.22",
     "awesome-typescript-loader": "^3.1.3",
@@ -53,6 +54,7 @@
   "dependencies": {
     "bignumber.js": "^4.0.2",
     "ethereumjs-util": "^5.1.1",
+    "jsonschema": "^1.1.1",
     "web3": "^0.19.0"
   }
 }

src/ts/0x.js.ts

@@ -1,6 +1,7 @@
 import * as BigNumber from 'bignumber.js';
 import * as ethUtil from 'ethereumjs-util';
 import {assert} from './utils/assert';
+import {ECSignatureSchema} from './schemas/ec_signature_schema';
 
 /**
  * Elliptic Curve signature
@@ -18,7 +19,7 @@ export class ZeroEx {
      */
     public static isValidSignature(data: string, signature: ECSignature, signer: ETHAddressHex): boolean {
         assert.isString('data', data);
-        assert.isObject('signature', signature);
+        assert.doesConformToSchema('signature', signature, ECSignatureSchema);
         assert.isETHAddressHex('signer', signer);
 
         const dataBuff = ethUtil.toBuffer(data);

src/ts/globals.d.ts

@@ -2,6 +2,10 @@ declare type ETHPublicKey = string;
 declare type ETHAddressHex = string;
 declare type ETHAddressBuff = Buffer;
 
+declare interface Schema {
+    id: string;
+}
+
 declare module 'ethereumjs-util' {
     const toBuffer: (data: string) => Buffer;
     const hashPersonalMessage: (msg: Buffer) => Buffer;

src/ts/schemas/ec_signature_schema.ts

@@ -0,0 +1,10 @@
+export const ECSignatureSchema = {
+    id: '/ECSignature',
+    properties: {
+        v: {type: 'number'},
+        r: {type: 'string'},
+        s: {type: 'string'},
+    },
+    required: ['v', 'r', 's'],
+    type: 'object',
+};

src/ts/utils/assert.ts

@@ -1,6 +1,7 @@
 import * as _ from 'lodash';
 import * as BigNumber from 'bignumber.js';
 import Web3 = require('web3');
+import {SchemaValidator} from './schema_validator';
 
 export const assert = {
     isBigNumber(variableName: string, value: BigNumber.BigNumber) {
@@ -14,12 +15,16 @@ export const assert = {
         const web3 = new Web3();
         this.assert(web3.isAddress(value), this.typeAssertionMessage(variableName, 'ETHAddressHex', value));
     },
-    isObject(variableName: string, value: object) {
-        this.assert(_.isObject(value), this.typeAssertionMessage(variableName, 'object', value));
-    },
     isNumber(variableName: string, value: number) {
         this.assert(_.isFinite(value), this.typeAssertionMessage(variableName, 'number', value));
     },
+    doesConformToSchema(variableName: string, value: object, schema: Schema) {
+        const schemaValidator = new SchemaValidator();
+        const validationResult = schemaValidator.validate(value, schema);
+        const hasValidationErrors = validationResult.errors.length > 0;
+        const assertMsg = `Expected ${variableName} to conform to schema ${schema.id}, encountered: $value`;
+        this.assert(!hasValidationErrors, assertMsg);
+    },
     assert(condition: boolean, message: string) {
         if (!condition) {
             throw new Error(message);

src/ts/utils/schema_validator.ts

@@ -0,0 +1,13 @@
+import {Validator as V, ValidatorResult} from 'jsonschema';
+import {ECSignatureSchema} from '../schemas/ec_signature_schema';
+
+export class SchemaValidator {
+    private v: V;
+    constructor() {
+        this.v = new V();
+        this.v.addSchema(ECSignatureSchema, ECSignatureSchema.id);
+    }
+    public validate(instance: object, schema: Schema): ValidatorResult {
+        return this.v.validate(instance, schema);
+    }
+}