Throw and handle errors from Providers.

In web3 wrapper when a response contains an error field we throw this rather than return response.result which is often undefined.
In Signature Utils we handle the error thrown when a user rejects the signing dialogue to prevent double signing.
Exposed the ZeroExTransaction JSON schema.
In Website only use the MetamaskSubprovider if we can detect the provider is Metamask

23 files changed, 208 insertions, 150 deletions

diff --git a/packages/0x.js/CHANGELOG.json b/packages/0x.js/CHANGELOG.json
index 3a184382c..6dfcc3d33 100644
--- a/packages/0x.js/CHANGELOG.json
+++ b/packages/0x.js/CHANGELOG.json
@@ -7,7 +7,8 @@
                 "pr": 1102
             },
             {
-                "note": "Added `MetamaskSubprovider` to handle inconsistencies with signing.",
+                "note":
+                    "Added `MetamaskSubprovider` to handle inconsistencies in Metamask's signing JSON RPC endpoints.",
                 "pr": 1102
             },
             {
diff --git a/packages/0x.js/src/index.ts b/packages/0x.js/src/index.ts
index 228bcecdb..6eb1fd8ee 100644
--- a/packages/0x.js/src/index.ts
+++ b/packages/0x.js/src/index.ts
@@ -90,6 +90,7 @@ export {
     JSONRPCRequestPayload,
     JSONRPCResponsePayload,
     JSONRPCErrorCallback,
+    JSONRPCResponseError,
     LogEntry,
     DecodedLogArgs,
     LogEntryEvent,
diff --git a/packages/contract-wrappers/src/utils/transaction_encoder.ts b/packages/contract-wrappers/src/utils/transaction_encoder.ts
index d9735778e..33086944b 100644
--- a/packages/contract-wrappers/src/utils/transaction_encoder.ts
+++ b/packages/contract-wrappers/src/utils/transaction_encoder.ts
@@ -33,7 +33,7 @@ export class TransactionEncoder {
             data,
         };
         const typedData = eip712Utils.createZeroExTransactionTypedData(executeTransactionData, exchangeAddress);
-        const eip712MessageBuffer = signTypedDataUtils.signTypedDataHash(typedData);
+        const eip712MessageBuffer = signTypedDataUtils.generateTypedDataHash(typedData);
         const messageHex = `0x${eip712MessageBuffer.toString('hex')}`;
         return messageHex;
     }
diff --git a/packages/contracts/test/utils/transaction_factory.ts b/packages/contracts/test/utils/transaction_factory.ts
index 6e4cc4b2f..9ed4c5a31 100644
--- a/packages/contracts/test/utils/transaction_factory.ts
+++ b/packages/contracts/test/utils/transaction_factory.ts
@@ -25,7 +25,7 @@ export class TransactionFactory {
         };
 
         const typedData = eip712Utils.createZeroExTransactionTypedData(executeTransactionData, this._exchangeAddress);
-        const eip712MessageBuffer = signTypedDataUtils.signTypedDataHash(typedData);
+        const eip712MessageBuffer = signTypedDataUtils.generateTypedDataHash(typedData);
         const signature = signingUtils.signMessage(eip712MessageBuffer, this._privateKey, signatureType);
         const signedTx = {
             exchangeAddress: this._exchangeAddress,
diff --git a/packages/ethereum-types/CHANGELOG.json b/packages/ethereum-types/CHANGELOG.json
index e955f4d04..60fb8c806 100644
--- a/packages/ethereum-types/CHANGELOG.json
+++ b/packages/ethereum-types/CHANGELOG.json
@@ -1,5 +1,14 @@
 [
     {
+        "version": "1.1.0",
+        "changes": [
+            {
+                "note": "Add `JSONRPCResponseError` and error field on `JSONRPCResponsePayload`.",
+                "pr": 1102
+            }
+        ]
+    },
+    {
         "timestamp": 1538693146,
         "version": "1.0.11",
         "changes": [
diff --git a/packages/ethereum-types/src/index.ts b/packages/ethereum-types/src/index.ts
index 7e8b9de3e..ddd472010 100644
--- a/packages/ethereum-types/src/index.ts
+++ b/packages/ethereum-types/src/index.ts
@@ -113,10 +113,16 @@ export interface JSONRPCRequestPayload {
     jsonrpc: string;
 }
 
+export interface JSONRPCResponseError {
+    message: string;
+    code: number;
+}
+
 export interface JSONRPCResponsePayload {
     result: any;
     id: number;
     jsonrpc: string;
+    error?: JSONRPCResponseError;
 }
 
 export interface AbstractBlock {
diff --git a/packages/json-schemas/schemas/eip712_typed_data.ts b/packages/json-schemas/schemas/eip712_typed_data.ts
index 371ff8a78..31ad74610 100644
--- a/packages/json-schemas/schemas/eip712_typed_data.ts
+++ b/packages/json-schemas/schemas/eip712_typed_data.ts
@@ -1,4 +1,4 @@
-export const eip712TypedData = {
+export const eip712TypedDataSchema = {
     id: '/eip712TypedData',
     type: 'object',
     properties: {
diff --git a/packages/json-schemas/schemas/zero_ex_transaction_schema.ts b/packages/json-schemas/schemas/zero_ex_transaction_schema.ts
new file mode 100644
index 000000000..7f729b724
--- /dev/null
+++ b/packages/json-schemas/schemas/zero_ex_transaction_schema.ts
@@ -0,0 +1,10 @@
+export const zeroExTransactionSchema = {
+    id: '/zeroExTransactionSchema',
+    properties: {
+        data: { $ref: '/hexSchema' },
+        signerAddress: { $ref: '/addressSchema' },
+        salt: { $ref: '/numberSchema' },
+    },
+    required: ['data', 'salt', 'signerAddress'],
+    type: 'object',
+};
diff --git a/packages/json-schemas/src/schemas.ts b/packages/json-schemas/src/schemas.ts
index 50dc8d091..4eb96092d 100644
--- a/packages/json-schemas/src/schemas.ts
+++ b/packages/json-schemas/src/schemas.ts
@@ -2,7 +2,7 @@ import { addressSchema, hexSchema, numberSchema } from '../schemas/basic_type_sc
 import { blockParamSchema, blockRangeSchema } from '../schemas/block_range_schema';
 import { callDataSchema } from '../schemas/call_data_schema';
 import { ecSignatureParameterSchema, ecSignatureSchema } from '../schemas/ec_signature_schema';
-import { eip712TypedData } from '../schemas/eip712_typed_data';
+import { eip712TypedDataSchema } from '../schemas/eip712_typed_data';
 import { indexFilterValuesSchema } from '../schemas/index_filter_values_schema';
 import { orderCancellationRequestsSchema } from '../schemas/order_cancel_schema';
 import { orderFillOrKillRequestsSchema } from '../schemas/order_fill_or_kill_requests_schema';
@@ -32,6 +32,7 @@ import { relayerApiOrdersSchema } from '../schemas/relayer_api_orders_schema';
 import { signedOrdersSchema } from '../schemas/signed_orders_schema';
 import { tokenSchema } from '../schemas/token_schema';
 import { jsNumber, txDataSchema } from '../schemas/tx_data_schema';
+import { zeroExTransactionSchema } from '../schemas/zero_ex_transaction_schema';
 
 export const schemas = {
     numberSchema,
@@ -40,7 +41,7 @@ export const schemas = {
     hexSchema,
     ecSignatureParameterSchema,
     ecSignatureSchema,
-    eip712TypedData,
+    eip712TypedDataSchema,
     indexFilterValuesSchema,
     orderCancellationRequestsSchema,
     orderFillOrKillRequestsSchema,
@@ -70,4 +71,5 @@ export const schemas = {
     relayerApiOrdersChannelUpdateSchema,
     relayerApiOrdersResponseSchema,
     relayerApiAssetDataPairsSchema,
+    zeroExTransactionSchema,
 };
diff --git a/packages/order-utils/src/eip712_utils.ts b/packages/order-utils/src/eip712_utils.ts
index 43b421de7..56f736500 100644
--- a/packages/order-utils/src/eip712_utils.ts
+++ b/packages/order-utils/src/eip712_utils.ts
@@ -1,3 +1,5 @@
+import { assert } from '@0xproject/assert';
+import { schemas } from '@0xproject/json-schemas';
 import { EIP712Object, EIP712TypedData, EIP712Types, Order, ZeroExTransaction } from '@0xproject/types';
 import * as _ from 'lodash';
 
@@ -18,6 +20,8 @@ export const eip712Utils = {
         message: EIP712Object,
         exchangeAddress: string,
     ): EIP712TypedData => {
+        assert.isETHAddressHex('exchangeAddress', exchangeAddress);
+        assert.isString('primaryType', primaryType);
         const typedData = {
             types: {
                 EIP712Domain: constants.EIP712_DOMAIN_SCHEMA.parameters,
@@ -31,6 +35,7 @@ export const eip712Utils = {
             message,
             primaryType,
         };
+        assert.doesConformToSchema('typedData', typedData, schemas.eip712TypedDataSchema);
         return typedData;
     },
     /**
@@ -39,6 +44,7 @@ export const eip712Utils = {
      * @return  A typed data object
      */
     createOrderTypedData: (order: Order): EIP712TypedData => {
+        assert.doesConformToSchema('order', order, schemas.orderSchema, [schemas.hexSchema]);
         const normalizedOrder = _.mapValues(order, value => {
             return !_.isString(value) ? value.toString() : value;
         });
@@ -61,6 +67,8 @@ export const eip712Utils = {
         zeroExTransaction: ZeroExTransaction,
         exchangeAddress: string,
     ): EIP712TypedData => {
+        assert.isETHAddressHex('exchangeAddress', exchangeAddress);
+        assert.doesConformToSchema('zeroExTransaction', zeroExTransaction, schemas.zeroExTransactionSchema);
         const normalizedTransaction = _.mapValues(zeroExTransaction, value => {
             return !_.isString(value) ? value.toString() : value;
         });
diff --git a/packages/order-utils/src/order_hash.ts b/packages/order-utils/src/order_hash.ts
index a6dd6688c..b523a3523 100644
--- a/packages/order-utils/src/order_hash.ts
+++ b/packages/order-utils/src/order_hash.ts
@@ -52,7 +52,7 @@ export const orderHashUtils = {
      */
     getOrderHashBuffer(order: SignedOrder | Order): Buffer {
         const typedData = eip712Utils.createOrderTypedData(order);
-        const orderHashBuff = signTypedDataUtils.signTypedDataHash(typedData);
+        const orderHashBuff = signTypedDataUtils.generateTypedDataHash(typedData);
         return orderHashBuff;
     },
 };
diff --git a/packages/order-utils/src/signature_utils.ts b/packages/order-utils/src/signature_utils.ts
index e518b29a0..2605ccd32 100644
--- a/packages/order-utils/src/signature_utils.ts
+++ b/packages/order-utils/src/signature_utils.ts
@@ -194,7 +194,7 @@ export const signatureUtils = {
         }
     },
     /**
-     * Signs an order and returns its elliptic curve signature and signature type. First `eth_signTypedData` is requested
+     * Signs an order and returns a SignedOrder. First `eth_signTypedData` is requested
      * then a fallback to `eth_sign` if not available on the supplied provider.
      * @param   order The Order to sign.
      * @param   signerAddress   The hex encoded Ethereum address you wish to sign it with. This address
@@ -202,11 +202,18 @@ export const signatureUtils = {
      * @return  A SignedOrder containing the order and Elliptic curve signature with Signature Type.
      */
     async ecSignOrderAsync(provider: Provider, order: Order, signerAddress: string): Promise<SignedOrder> {
+        assert.doesConformToSchema('order', order, schemas.orderSchema, [schemas.hexSchema]);
         try {
-            const signedOrder = signatureUtils.ecSignTypedDataOrderAsync(provider, order, signerAddress);
+            const signedOrder = await signatureUtils.ecSignTypedDataOrderAsync(provider, order, signerAddress);
             return signedOrder;
         } catch (err) {
-            // Fallback to using EthSign when ethSignTypedData is not supported
+            // HACK: We are unable to handle specific errors thrown since provider is not an object
+            //       under our control. It could be Metamask Web3, Ethers, or any general RPC provider.
+            //       We check for a user denying the signature request in a way that supports Metamask and
+            //       Coinbase Wallet
+            if (err.message.includes('User denied message signature')) {
+                throw err;
+            }
             const orderHash = orderHashUtils.getOrderHashHex(order);
             const signatureHex = await signatureUtils.ecSignHashAsync(provider, orderHash, signerAddress);
             const signedOrder = {
@@ -217,7 +224,7 @@ export const signatureUtils = {
         }
     },
     /**
-     * Signs an order using `eth_signTypedData` and returns its elliptic curve signature and signature type.
+     * Signs an order using `eth_signTypedData` and returns a SignedOrder.
      * @param   order The Order to sign.
      * @param   signerAddress   The hex encoded Ethereum address you wish to sign it with. This address
      *          must be available via the supplied Provider.
@@ -226,6 +233,7 @@ export const signatureUtils = {
     async ecSignTypedDataOrderAsync(provider: Provider, order: Order, signerAddress: string): Promise<SignedOrder> {
         assert.isWeb3Provider('provider', provider);
         assert.isETHAddressHex('signerAddress', signerAddress);
+        assert.doesConformToSchema('order', order, schemas.orderSchema, [schemas.hexSchema]);
         const web3Wrapper = new Web3Wrapper(provider);
         await assert.isSenderAddressAsync('signerAddress', signerAddress, web3Wrapper);
         const normalizedSignerAddress = signerAddress.toLowerCase();
@@ -247,14 +255,16 @@ export const signatureUtils = {
         } catch (err) {
             // Detect if Metamask to transition users to the MetamaskSubprovider
             if ((provider as any).isMetaMask) {
-                throw new Error(`Unsupported Provider, please use MetamaskSubprovider: ${err.message}`);
+                throw new Error(
+                    `MetaMask provider must be wrapped in a MetamaskSubprovider (from the '@0xproject/subproviders' package) in order to work with this method.`,
+                );
             } else {
                 throw err;
             }
         }
     },
     /**
-     * Signs a hash and returns its elliptic curve signature and signature type.
+     * Signs a hash using `eth_sign` and returns its elliptic curve signature and signature type.
      * @param   msgHash       Hex encoded message to sign.
      * @param   signerAddress   The hex encoded Ethereum address you wish to sign it with. This address
      *          must be available via the supplied Provider.
@@ -303,7 +313,9 @@ export const signatureUtils = {
         }
         // Detect if Metamask to transition users to the MetamaskSubprovider
         if ((provider as any).isMetaMask) {
-            throw new Error('Unsupported Provider, please use MetamaskSubprovider.');
+            throw new Error(
+                `MetaMask provider must be wrapped in a MetamaskSubprovider (from the '@0xproject/subproviders' package) in order to work with this method.`,
+            );
         } else {
             throw new Error(OrderError.InvalidSignature);
         }
diff --git a/packages/order-utils/test/eip712_utils_test.ts b/packages/order-utils/test/eip712_utils_test.ts
index dc76595db..d65cabe9c 100644
--- a/packages/order-utils/test/eip712_utils_test.ts
+++ b/packages/order-utils/test/eip712_utils_test.ts
@@ -33,7 +33,7 @@ describe('EIP712 Utils', () => {
                 {
                     salt: new BigNumber('0'),
                     data: constants.NULL_BYTES,
-                    signerAddress: constants.NULL_BYTES,
+                    signerAddress: constants.NULL_ADDRESS,
                 },
                 constants.NULL_ADDRESS,
             );
diff --git a/packages/order-utils/test/signature_utils_test.ts b/packages/order-utils/test/signature_utils_test.ts
index 7f6987f6a..f2d6790fb 100644
--- a/packages/order-utils/test/signature_utils_test.ts
+++ b/packages/order-utils/test/signature_utils_test.ts
@@ -17,6 +17,28 @@ chaiSetup.configure();
 const expect = chai.expect;
 
 describe('Signature utils', () => {
+    let makerAddress: string;
+    const fakeExchangeContractAddress = '0x1dc4c1cefef38a777b15aa20260a54e584b16c48';
+    let order: Order;
+    before(async () => {
+        const availableAddreses = await web3Wrapper.getAvailableAddressesAsync();
+        makerAddress = availableAddreses[0];
+        order = {
+            makerAddress,
+            takerAddress: constants.NULL_ADDRESS,
+            senderAddress: constants.NULL_ADDRESS,
+            feeRecipientAddress: constants.NULL_ADDRESS,
+            makerAssetData: constants.NULL_ADDRESS,
+            takerAssetData: constants.NULL_ADDRESS,
+            exchangeAddress: fakeExchangeContractAddress,
+            salt: new BigNumber(0),
+            makerFee: new BigNumber(0),
+            takerFee: new BigNumber(0),
+            makerAssetAmount: new BigNumber(0),
+            takerAssetAmount: new BigNumber(0),
+            expirationTimeSeconds: new BigNumber(0),
+        };
+    });
     describe('#isValidSignatureAsync', () => {
         let dataHex = '0x6927e990021d23b1eb7b8789f6a6feaf98fe104bb0cf8259421b79f9a34222b0';
         const ethSignSignature =
@@ -117,54 +139,54 @@ describe('Signature utils', () => {
         });
     });
     describe('#ecSignOrderAsync', () => {
-        let makerAddress: string;
-        const fakeExchangeContractAddress = '0x1dc4c1cefef38a777b15aa20260a54e584b16c48';
-        let order: Order;
-        before(async () => {
-            const availableAddreses = await web3Wrapper.getAvailableAddressesAsync();
-            makerAddress = availableAddreses[0];
-            order = {
-                makerAddress,
-                takerAddress: constants.NULL_ADDRESS,
-                senderAddress: constants.NULL_ADDRESS,
-                feeRecipientAddress: constants.NULL_ADDRESS,
-                makerAssetData: constants.NULL_ADDRESS,
-                takerAssetData: constants.NULL_ADDRESS,
-                exchangeAddress: fakeExchangeContractAddress,
-                salt: new BigNumber(0),
-                makerFee: new BigNumber(0),
-                takerFee: new BigNumber(0),
-                makerAssetAmount: new BigNumber(0),
-                takerAssetAmount: new BigNumber(0),
-                expirationTimeSeconds: new BigNumber(0),
+        it('should default to eth_sign if eth_signTypedData is unavailable', async () => {
+            const expectedSignature =
+                '0x1c3582f06356a1314dbf1c0e534c4d8e92e59b056ee607a7ff5a825f5f2cc5e6151c5cc7fdd420f5608e4d5bef108e42ad90c7a4b408caef32e24374cf387b0d7603';
+
+            const fakeProvider = {
+                async sendAsync(payload: JSONRPCRequestPayload, callback: JSONRPCErrorCallback): Promise<void> {
+                    if (payload.method === 'eth_signTypedData') {
+                        callback(new Error('Internal RPC Error'));
+                    } else if (payload.method === 'eth_sign') {
+                        const [address, message] = payload.params;
+                        const signature = await web3Wrapper.signMessageAsync(address, message);
+                        callback(null, {
+                            id: 42,
+                            jsonrpc: '2.0',
+                            result: signature,
+                        });
+                    } else {
+                        callback(null, { id: 42, jsonrpc: '2.0', result: [makerAddress] });
+                    }
+                },
             };
+            const signedOrder = await signatureUtils.ecSignOrderAsync(fakeProvider, order, makerAddress);
+            expect(signedOrder.signature).to.equal(expectedSignature);
         });
-        it('should result in the same signature as signing order hash without prefix', async () => {
-            const orderHashHex = orderHashUtils.getOrderHashHex(order);
-            const sig = ethUtil.ecsign(
-                ethUtil.toBuffer(orderHashHex),
-                Buffer.from('F2F48EE19680706196E2E339E5DA3491186E0C4C5030670656B0E0164837257D', 'hex'),
-            );
-            const signatureBuffer = Buffer.concat([
-                ethUtil.toBuffer(sig.v),
-                ethUtil.toBuffer(sig.r),
-                ethUtil.toBuffer(sig.s),
-                ethUtil.toBuffer(SignatureType.EIP712),
-            ]);
-            const signatureHex = `0x${signatureBuffer.toString('hex')}`;
-            const signedOrder = await signatureUtils.ecSignOrderAsync(provider, order, makerAddress);
-            const isValidSignature = await signatureUtils.isValidSignatureAsync(
-                provider,
-                orderHashHex,
-                signedOrder.signature,
-                makerAddress,
+        it('should throw if the user denies the signing request', async () => {
+            const fakeProvider = {
+                async sendAsync(payload: JSONRPCRequestPayload, callback: JSONRPCErrorCallback): Promise<void> {
+                    if (payload.method === 'eth_signTypedData') {
+                        callback(new Error('User denied message signature'));
+                    } else if (payload.method === 'eth_sign') {
+                        const [address, message] = payload.params;
+                        const signature = await web3Wrapper.signMessageAsync(address, message);
+                        callback(null, {
+                            id: 42,
+                            jsonrpc: '2.0',
+                            result: signature,
+                        });
+                    } else {
+                        callback(null, { id: 42, jsonrpc: '2.0', result: [makerAddress] });
+                    }
+                },
+            };
+            expect(signatureUtils.ecSignOrderAsync(fakeProvider, order, makerAddress)).to.to.be.rejectedWith(
+                'User denied message signature',
             );
-            expect(signatureHex).to.eq(signedOrder.signature);
-            expect(isValidSignature).to.eq(true);
         });
     });
     describe('#ecSignHashAsync', () => {
-        let makerAddress: string;
         before(async () => {
             const availableAddreses = await web3Wrapper.getAvailableAddressesAsync();
             makerAddress = availableAddreses[0];
@@ -239,27 +261,30 @@ describe('Signature utils', () => {
         });
     });
     describe('#ecSignTypedDataOrderAsync', () => {
-        let makerAddress: string;
-        const fakeExchangeContractAddress = '0x1dc4c1cefef38a777b15aa20260a54e584b16c48';
-        let order: Order;
-        before(async () => {
-            const availableAddreses = await web3Wrapper.getAvailableAddressesAsync();
-            makerAddress = availableAddreses[0];
-            order = {
+        it('should result in the same signature as signing the order hash without an ethereum message prefix', async () => {
+            // Note: Since order hash is an EIP712 hash the result of a valid EIP712 signature
+            //       of order hash is the same as signing the order without the Ethereum Message prefix.
+            const orderHashHex = orderHashUtils.getOrderHashHex(order);
+            const sig = ethUtil.ecsign(
+                ethUtil.toBuffer(orderHashHex),
+                Buffer.from('F2F48EE19680706196E2E339E5DA3491186E0C4C5030670656B0E0164837257D', 'hex'),
+            );
+            const signatureBuffer = Buffer.concat([
+                ethUtil.toBuffer(sig.v),
+                ethUtil.toBuffer(sig.r),
+                ethUtil.toBuffer(sig.s),
+                ethUtil.toBuffer(SignatureType.EIP712),
+            ]);
+            const signatureHex = `0x${signatureBuffer.toString('hex')}`;
+            const signedOrder = await signatureUtils.ecSignTypedDataOrderAsync(provider, order, makerAddress);
+            const isValidSignature = await signatureUtils.isValidSignatureAsync(
+                provider,
+                orderHashHex,
+                signedOrder.signature,
                 makerAddress,
-                takerAddress: constants.NULL_ADDRESS,
-                senderAddress: constants.NULL_ADDRESS,
-                feeRecipientAddress: constants.NULL_ADDRESS,
-                makerAssetData: constants.NULL_ADDRESS,
-                takerAssetData: constants.NULL_ADDRESS,
-                exchangeAddress: fakeExchangeContractAddress,
-                salt: new BigNumber(0),
-                makerFee: new BigNumber(0),
-                takerFee: new BigNumber(0),
-                makerAssetAmount: new BigNumber(0),
-                takerAssetAmount: new BigNumber(0),
-                expirationTimeSeconds: new BigNumber(0),
-            };
+            );
+            expect(signatureHex).to.eq(signedOrder.signature);
+            expect(isValidSignature).to.eq(true);
         });
         it('should return the correct Signature for signatureHex concatenated as R + S + V', async () => {
             const expectedSignature =
diff --git a/packages/subproviders/src/index.ts b/packages/subproviders/src/index.ts
index 6a8100e68..9f4dac58b 100644
--- a/packages/subproviders/src/index.ts
+++ b/packages/subproviders/src/index.ts
@@ -57,4 +57,10 @@ export {
     EIP712Parameter,
 } from '@0xproject/types';
 
-export { JSONRPCRequestPayload, Provider, JSONRPCResponsePayload, JSONRPCErrorCallback } from 'ethereum-types';
+export {
+    JSONRPCRequestPayload,
+    Provider,
+    JSONRPCResponsePayload,
+    JSONRPCErrorCallback,
+    JSONRPCResponseError,
+} from 'ethereum-types';
diff --git a/packages/subproviders/src/subproviders/private_key_wallet.ts b/packages/subproviders/src/subproviders/private_key_wallet.ts
index 96e4190ed..e89c4c186 100644
--- a/packages/subproviders/src/subproviders/private_key_wallet.ts
+++ b/packages/subproviders/src/subproviders/private_key_wallet.ts
@@ -106,7 +106,7 @@ export class PrivateKeyWalletSubprovider extends BaseWalletSubprovider {
                 `Requested to sign message with address: ${address}, instantiated with address: ${this._address}`,
             );
         }
-        const dataBuff = signTypedDataUtils.signTypedDataHash(typedData);
+        const dataBuff = signTypedDataUtils.generateTypedDataHash(typedData);
         const sig = ethUtil.ecsign(dataBuff, this._privateKeyBuffer);
         const rpcSig = ethUtil.toRpcSig(sig.v, sig.r, sig.s);
         return rpcSig;
diff --git a/packages/utils/src/sign_typed_data_utils.ts b/packages/utils/src/sign_typed_data_utils.ts
index 657a59ed0..cd5bcb42f 100644
--- a/packages/utils/src/sign_typed_data_utils.ts
+++ b/packages/utils/src/sign_typed_data_utils.ts
@@ -6,11 +6,11 @@ import { EIP712Object, EIP712ObjectValue, EIP712TypedData, EIP712Types } from '@
 
 export const signTypedDataUtils = {
     /**
-     * Computes the Sign Typed Data hash
+     * Generates the EIP712 Typed Data hash for signing
      * @param   typedData An object that conforms to the EIP712TypedData interface
-     * @return  A Buffer containing the hash of the sign typed data.
+     * @return  A Buffer containing the hash of the typed data.
      */
-    signTypedDataHash(typedData: EIP712TypedData): Buffer {
+    generateTypedDataHash(typedData: EIP712TypedData): Buffer {
         return ethUtil.sha3(
             Buffer.concat([
                 Buffer.from('1901', 'hex'),
diff --git a/packages/utils/test/sign_typed_data_utils_test.ts b/packages/utils/test/sign_typed_data_utils_test.ts
index e1cb4f6e1..dcba08b04 100644
--- a/packages/utils/test/sign_typed_data_utils_test.ts
+++ b/packages/utils/test/sign_typed_data_utils_test.ts
@@ -127,12 +127,12 @@ describe('signTypedDataUtils', () => {
             primaryType: 'Order',
         };
         it('creates a hash of the test sign typed data', () => {
-            const hash = signTypedDataUtils.signTypedDataHash(simpleSignTypedData).toString('hex');
+            const hash = signTypedDataUtils.generateTypedDataHash(simpleSignTypedData).toString('hex');
             const hashHex = `0x${hash}`;
             expect(hashHex).to.be.eq(simpleSignTypedDataHashHex);
         });
         it('creates a hash of the order sign typed data', () => {
-            const hash = signTypedDataUtils.signTypedDataHash(orderSignTypedData).toString('hex');
+            const hash = signTypedDataUtils.generateTypedDataHash(orderSignTypedData).toString('hex');
             const hashHex = `0x${hash}`;
             expect(hashHex).to.be.eq(orderSignTypedDataHashHex);
         });
diff --git a/packages/web3-wrapper/CHANGELOG.json b/packages/web3-wrapper/CHANGELOG.json
index 47f054300..be5c1fef6 100644
--- a/packages/web3-wrapper/CHANGELOG.json
+++ b/packages/web3-wrapper/CHANGELOG.json
@@ -1,5 +1,19 @@
 [
     {
+        "version": "3.1.0",
+        "changes": [
+            {
+                "note": "Add `signTypedData` to perform EIP712 `eth_signTypedData`.",
+                "pr": 1102
+            },
+            {
+                "note":
+                    "Web3Wrapper now throws when an RPC request contains an error field in the response. Previously errors could be swallowed and undefined returned.",
+                "pr": 1102
+            }
+        ]
+    },
+    {
         "version": "3.0.3",
         "changes": [
             {
diff --git a/packages/web3-wrapper/src/web3_wrapper.ts b/packages/web3-wrapper/src/web3_wrapper.ts
index 034bafb5f..726246f1a 100644
--- a/packages/web3-wrapper/src/web3_wrapper.ts
+++ b/packages/web3-wrapper/src/web3_wrapper.ts
@@ -322,7 +322,7 @@ export class Web3Wrapper {
      */
     public async signTypedDataAsync(address: string, typedData: any): Promise<string> {
         assert.isETHAddressHex('address', address);
-        assert.doesConformToSchema('typedData', typedData, schemas.eip712TypedData);
+        assert.doesConformToSchema('typedData', typedData, schemas.eip712TypedDataSchema);
         const signData = await this.sendRawPayloadAsync<string>({
             method: 'eth_signTypedData',
             params: [address, typedData],
@@ -669,6 +669,9 @@ export class Web3Wrapper {
             ...payload,
         };
         const response = await promisify<JSONRPCResponsePayload>(sendAsync)(payloadWithDefaults);
+        if (response.error) {
+            throw new Error(response.error.message);
+        }
         const result = response.result;
         return result;
     }
diff --git a/packages/web3-wrapper/test/web3_wrapper_test.ts b/packages/web3-wrapper/test/web3_wrapper_test.ts
index 385c469bf..164253777 100644
--- a/packages/web3-wrapper/test/web3_wrapper_test.ts
+++ b/packages/web3-wrapper/test/web3_wrapper_test.ts
@@ -1,5 +1,5 @@
 import * as chai from 'chai';
-import { BlockParamLiteral } from 'ethereum-types';
+import { BlockParamLiteral, JSONRPCErrorCallback, JSONRPCRequestPayload } from 'ethereum-types';
 import * as Ganache from 'ganache-core';
 import * as _ from 'lodash';
 import 'mocha';
@@ -78,6 +78,19 @@ describe('Web3Wrapper tests', () => {
             const signatureLength = 132;
             expect(signature.length).to.be.equal(signatureLength);
         });
+        it('should throw if the provider returns an error', async () => {
+            const message = '0xdeadbeef';
+            const signer = addresses[1];
+            const fakeProvider = {
+                async sendAsync(payload: JSONRPCRequestPayload, callback: JSONRPCErrorCallback): Promise<void> {
+                    callback(new Error('User denied message signature'));
+                },
+            };
+            const errorWeb3Wrapper = new Web3Wrapper(fakeProvider);
+            expect(errorWeb3Wrapper.signMessageAsync(signer, message)).to.be.rejectedWith(
+                'User denied message signature',
+            );
+        });
     });
     describe('#getBlockNumberAsync', () => {
         it('get block number', async () => {
diff --git a/packages/website/ts/blockchain.ts b/packages/website/ts/blockchain.ts
index 652f2eb1d..b1181e4c6 100644
--- a/packages/website/ts/blockchain.ts
+++ b/packages/website/ts/blockchain.ts
@@ -17,6 +17,7 @@ import {
     MetamaskSubprovider,
     RedundantSubprovider,
     RPCSubprovider,
+    SignerSubprovider,
     Web3ProviderEngine,
 } from '@0xproject/subproviders';
 import { SignedOrder, Token as ZeroExToken } from '@0xproject/types';
@@ -27,8 +28,6 @@ import * as _ from 'lodash';
 import * as moment from 'moment';
 import * as React from 'react';
 import contract = require('truffle-contract');
-import { tokenAddressOverrides } from 'ts/utils/token_address_overrides';
-
 import { BlockchainWatcher } from 'ts/blockchain_watcher';
 import { AssetSendCompleted } from 'ts/components/flash_messages/asset_send_completed';
 import { TransactionSubmitted } from 'ts/components/flash_messages/transaction_submitted';
@@ -54,6 +53,7 @@ import { backendClient } from 'ts/utils/backend_client';
 import { configs } from 'ts/utils/configs';
 import { constants } from 'ts/utils/constants';
 import { errorReporter } from 'ts/utils/error_reporter';
+import { tokenAddressOverrides } from 'ts/utils/token_address_overrides';
 import { utils } from 'ts/utils/utils';
 import FilterSubprovider = require('web3-provider-engine/subproviders/filters');
 
@@ -161,7 +161,13 @@ export class Blockchain {
             // We catch all requests involving a users account and send it to the injectedWeb3
             // instance. All other requests go to the public hosted node.
             const provider = new Web3ProviderEngine();
-            provider.addProvider(new MetamaskSubprovider(injectedWeb3.currentProvider));
+            const providerName = this._getNameGivenProvider(injectedWeb3.currentProvider);
+            // Wrap Metamask in a compatability wrapper MetamaskSubprovider (to handle inconsistencies)
+            const signerSubprovider =
+                providerName === Providers.Metamask
+                    ? new MetamaskSubprovider(injectedWeb3.currentProvider)
+                    : new SignerSubprovider(injectedWeb3.currentProvider);
+            provider.addProvider(signerSubprovider);
             provider.addProvider(new FilterSubprovider());
             const rpcSubproviders = _.map(publicNodeUrlsIfExistsForNetworkId, publicNodeUrl => {
                 return new RPCSubprovider(publicNodeUrl);
diff --git a/yarn.lock b/yarn.lock
index 8dac36588..43485109e 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -5606,19 +5606,6 @@ ethereumjs-wallet@0.6.0:
     utf8 "^2.1.1"
     uuid "^2.0.1"
 
-ethereumjs-wallet@~0.6.0:
-  version "0.6.2"
-  resolved "https://registry.yarnpkg.com/ethereumjs-wallet/-/ethereumjs-wallet-0.6.2.tgz#67244b6af3e8113b53d709124b25477b64aeccda"
-  dependencies:
-    aes-js "^3.1.1"
-    bs58check "^2.1.2"
-    ethereumjs-util "^5.2.0"
-    hdkey "^1.0.0"
-    safe-buffer "^5.1.2"
-    scrypt.js "^0.2.0"
-    utf8 "^3.0.0"
-    uuid "^3.3.2"
-
 ethers@3.0.22:
   version "3.0.22"
   resolved "https://registry.yarnpkg.com/ethers/-/ethers-3.0.22.tgz#7fab1ea16521705837aa43c15831877b2716b436"
@@ -6432,7 +6419,7 @@ ganache-core@0xProject/ganache-core#monorepo-dep:
     ethereumjs-tx "0xProject/ethereumjs-tx#fake-tx-include-signature-by-default"
     ethereumjs-util "^5.2.0"
     ethereumjs-vm "2.3.5"
-    ethereumjs-wallet "0.6.0"
+    ethereumjs-wallet "~0.6.0"
     fake-merkle-patricia-tree "~1.0.1"
     heap "~0.2.6"
     js-scrypt "^0.2.0"
@@ -6797,7 +6784,7 @@ globby@^6.1.0:
     pify "^2.0.0"
     pinkie-promise "^2.0.0"
 
-globby@^8.0.0, globby@^8.0.1:
+globby@^8.0.1:
   version "8.0.1"
   resolved "https://registry.yarnpkg.com/globby/-/globby-8.0.1.tgz#b5ad48b8aa80b35b814fc1281ecc851f1d2b5b50"
   dependencies:
@@ -8576,10 +8563,6 @@ jsesc@~0.5.0:
   version "0.5.0"
   resolved "https://registry.yarnpkg.com/jsesc/-/jsesc-0.5.0.tgz#e7dee66e35d6fc16f710fe91d5cf69f70f08911d"
 
-json-buffer@3.0.0:
-  version "3.0.0"
-  resolved "https://registry.yarnpkg.com/json-buffer/-/json-buffer-3.0.0.tgz#5b1f397afc75d677bde8bcfc0e47e1f9a3d9a898"
-
 json-parse-better-errors@^1.0.1, json-parse-better-errors@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/json-parse-better-errors/-/json-parse-better-errors-1.0.2.tgz#bb867cfb3450e69107c131d1c514bab3dc8bcaa9"
@@ -9357,7 +9340,7 @@ lodash@^4.13.1, lodash@^4.15.0:
   version "4.17.11"
   resolved "https://registry.npmjs.org/lodash/-/lodash-4.17.11.tgz#b39ea6229ef607ecd89e2c8df12536891cac9b8d"
 
-lodash@^4.14.0, lodash@^4.17.2, lodash@^4.17.4, lodash@^4.17.5, lodash@^4.2.1, lodash@^4.3.0, lodash@^4.5.1:
+lodash@^4.14.0, lodash@^4.17.4, lodash@^4.17.5, lodash@^4.2.1, lodash@^4.3.0, lodash@^4.5.1:
   version "4.17.5"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.5.tgz#99a92d65c0272debe8c96b6057bc8fbfa3bed511"
 
@@ -10882,10 +10865,6 @@ p-is-promise@^1.1.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/p-is-promise/-/p-is-promise-1.1.0.tgz#9c9456989e9f6588017b0434d56097675c3da05e"
 
-p-lazy@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/p-lazy/-/p-lazy-1.0.0.tgz#ec53c802f2ee3ac28f166cc82d0b2b02de27a835"
-
 p-limit@^1.1.0:
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/p-limit/-/p-limit-1.2.0.tgz#0e92b6bedcb59f022c13d0f1949dc82d15909f1c"
@@ -15834,12 +15813,6 @@ webidl-conversions@^4.0.2:
   version "4.0.2"
   resolved "https://registry.npmjs.org/webidl-conversions/-/webidl-conversions-4.0.2.tgz#a855980b1f0b6b359ba1d5d9fb39ae941faa63ad"
 
-webpack-addons@^1.1.5:
-  version "1.1.5"
-  resolved "https://registry.yarnpkg.com/webpack-addons/-/webpack-addons-1.1.5.tgz#2b178dfe873fb6e75e40a819fa5c26e4a9bc837a"
-  dependencies:
-    jscodeshift "^0.4.0"
-
 webpack-cli@3.1.2, webpack-cli@^3.1.1:
   version "3.1.2"
   resolved "https://registry.npmjs.org/webpack-cli/-/webpack-cli-3.1.2.tgz#17d7e01b77f89f884a2bbf9db545f0f6a648e746"
@@ -15855,37 +15828,6 @@ webpack-cli@3.1.2, webpack-cli@^3.1.1:
     v8-compile-cache "^2.0.2"
     yargs "^12.0.2"
 
-webpack-cli@^2.0.9:
-  version "2.1.3"
-  resolved "https://registry.yarnpkg.com/webpack-cli/-/webpack-cli-2.1.3.tgz#65d166851abaa56067ef3f716b02a97ba6bbe84d"
-  dependencies:
-    chalk "^2.3.2"
-    cross-spawn "^6.0.5"
-    diff "^3.5.0"
-    enhanced-resolve "^4.0.0"
-    envinfo "^4.4.2"
-    glob-all "^3.1.0"
-    global-modules "^1.0.0"
-    got "^8.2.0"
-    import-local "^1.0.0"
-    inquirer "^5.1.0"
-    interpret "^1.0.4"
-    jscodeshift "^0.5.0"
-    listr "^0.13.0"
-    loader-utils "^1.1.0"
-    lodash "^4.17.5"
-    log-symbols "^2.2.0"
-    mkdirp "^0.5.1"
-    p-each-series "^1.0.0"
-    p-lazy "^1.0.0"
-    prettier "^1.5.3"
-    supports-color "^5.3.0"
-    v8-compile-cache "^1.1.2"
-    webpack-addons "^1.1.5"
-    yargs "^11.1.0"
-    yeoman-environment "^2.0.0"
-    yeoman-generator "^2.0.4"
-
 webpack-dev-middleware@3.4.0:
   version "3.4.0"
   resolved "https://registry.npmjs.org/webpack-dev-middleware/-/webpack-dev-middleware-3.4.0.tgz#1132fecc9026fd90f0ecedac5cbff75d1fb45890"