more robust eth_signTypedData support

subproviders/CHANGELOG.json

@@ -1,4 +1,13 @@
 [
+    {
+        "version": "6.4.0",
+        "changes": [
+            {
+                "note": "Support `eth_signTypedData_v4` in `MetamaskSubprovider` and use the method name passed in",
+                "pr": 21
+            }
+        ]
+    },
     {
         "timestamp": 1610044030,
         "version": "6.3.2",

subproviders/src/subproviders/metamask_subprovider.ts

@@ -84,18 +84,21 @@ export class MetamaskSubprovider extends Subprovider {
                     end(err);
                 }
                 return;
+            // Metamask supports different versions of the `eth_signTypedData` RPC method.
             case 'eth_signTypedData':
             case 'eth_signTypedData_v3':
+            case 'eth_signTypedData_v4':
                 [address, message] = payload.params;
                 try {
-                    // Metamask supports multiple versions and has namespaced signTypedData to v3 for an indeterminate period of time.
-                    // eth_signTypedData is mapped to an older implementation before the spec was finalized.
-                    // Source: https://github.com/MetaMask/metamask-extension/blob/c49d854b55b3efd34c7fd0414b76f7feaa2eec7c/app/scripts/metamask-controller.js#L1262
-                    // and expects message to be serialised as JSON
-                    const messageJSON = JSON.stringify(message);
+                    // We accept either JSON-serialized or object messages.
+                    const messageObject = typeof message === 'object' ? message : JSON.parse(message);
                     const signature = await this._web3Wrapper.sendRawPayloadAsync<string>({
-                        method: 'eth_signTypedData_v3',
-                        params: [address, messageJSON],
+                        method: payload.method,
+                        // `eth_signTypedData` takes a raw object.
+                        params: [
+                            address,
+                            payload.method === 'eth_signTypedData' ? messageObject : JSON.stringify(messageObject),
+                        ],
                     });
                     signature ? end(null, signature) : end(new Error('Error performing eth_signTypedData'), null);
                 } catch (err) {

web3-wrapper/CHANGELOG.json

@@ -1,4 +1,13 @@
 [
+    {
+        "version": "7.4.0",
+        "changes": [
+            {
+                "note": "Remove `Web3Wrapper.signTypedDataV4Async()` and add backoff support for multiple versions of `eth_signTypedData` to `Web3Wrapper.signTypedDataAsync()`.",
+                "pr": 21
+            }
+        ]
+    },
     {
         "timestamp": 1610044030,
         "version": "7.3.2",

web3-wrapper/src/web3_wrapper.ts

@@ -342,26 +342,27 @@ export class Web3Wrapper {
     public async signTypedDataAsync(address: string, typedData: any): Promise<string> {
         assert.isETHAddressHex('address', address);
         assert.doesConformToSchema('typedData', typedData, schemas.eip712TypedDataSchema);
-        const signData = await this.sendRawPayloadAsync<string>({
-            method: 'eth_signTypedData',
-            params: [address, typedData],
-        });
-        return signData;
-    }
-    /**
-     * Sign an EIP712 typed data message with a specific address's private key (MetaMask's `eth_signTypedData_v4`)
-     * @param address Address of signer
-     * @param typedData Typed data message to sign
-     * @returns Signature string (as RSV)
-     */
-    public async signTypedDataV4Async(address: string, typedData: any): Promise<string> {
-        assert.isETHAddressHex('address', address);
-        assert.doesConformToSchema('typedData', typedData, schemas.eip712TypedDataSchema);
-        const signData = await this.sendRawPayloadAsync<string>({
-            method: 'eth_signTypedData_v4',
-            params: [address, JSON.stringify(typedData)],
-        });
-        return signData;
+        // Try decreasing versions of `eth_signTypedData` until it works.
+        const methodsToTry = ['eth_signTypedData_v4', 'eth_signTypedData_v3', 'eth_signTypedData'];
+        let lastErr: Error | undefined;
+        for (const method of methodsToTry) {
+            try {
+                return await this.sendRawPayloadAsync<string>({
+                    method,
+                    // `eth_signTypedData` expects an object, whereas the others expect
+                    // a JSON string.
+                    params: [address, method === 'eth_signTypedData' ? typedData : JSON.stringify(typedData)],
+                });
+            } catch (err) {
+                lastErr = err;
+                // If there are no more methods to try or the error says something other
+                // than the method not existing, throw.
+                if (!/(not handled|does not exist)/.test(err.message)) {
+                    throw err;
+                }
+            }
+        }
+        throw lastErr;
     }
     /**
      * Fetches the latest block number