From c198dc73c5b7a6a2f092ad2719506a88a062da39 Mon Sep 17 00:00:00 2001
From: Jakub Sydor <sydorjakub@gmail.com>
Date: Mon, 25 Jul 2022 11:38:01 +0200
Subject: [PATCH] fix: set check ethr signer for node clients (#618)

* fix: set check ethr signer for node clients

* test: add ethr signer tests
---
 e2e/signer.service.e2e.ts            | 16 ++++++++++++++++
 src/modules/signer/signer.service.ts | 28 ++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 e2e/signer.service.e2e.ts

diff --git a/e2e/signer.service.e2e.ts b/e2e/signer.service.e2e.ts
new file mode 100644
index 00000000..d955e506
--- /dev/null
+++ b/e2e/signer.service.e2e.ts
@@ -0,0 +1,16 @@
+import { providers, Wallet } from 'ethers';
+import { ProviderType, SignerService } from '../src';
+
+describe('Signer tests', () => {
+  it('should set `isEthrSigner` for node environment during initialization', async () => {
+    const wallet = Wallet.createRandom();
+    const provider = new providers.JsonRpcProvider('http://localhost:8544');
+    const service = new SignerService(
+      wallet.connect(provider),
+      ProviderType.PrivateKey
+    );
+    expect(service.isEthSigner).toBeUndefined();
+    await service.init();
+    expect(service.isEthSigner).toBe(true);
+  });
+});
diff --git a/src/modules/signer/signer.service.ts b/src/modules/signer/signer.service.ts
index 2f030e04..47ef3e7f 100644
--- a/src/modules/signer/signer.service.ts
+++ b/src/modules/signer/signer.service.ts
@@ -85,7 +85,10 @@ export class SignerService {
       } else if (isEthSigner === 'false') {
         this._isEthSigner = false;
       }
+    } else {
+      this._setIsEthrSigner();
     }
+
     /**
      * @todo provide general way to initialize with previously saved key
      */
@@ -502,4 +505,29 @@ export class SignerService {
       sig
     )}`;
   }
+
+  /**
+   * Set `_isEthSigner` value based on a signed message.
+   * Generates a test message and signs it.
+   */
+  private async _setIsEthrSigner() {
+    // arrayification is necessary for WalletConnect signatures to work. eth_sign expects message in bytes: https://docs.walletconnect.org/json-rpc-api-methods/ethereum#eth_sign
+    // keccak256 hash is applied for Metamask to display a coherent hex value when signing
+    const message = arrayify(keccak256('0x'));
+    // Computation of the digest in order to recover the public key under the assumption
+    // that signature was performed as per the eth_sign spec (https://eth.wiki/json-rpc/API#eth_sign)
+    const digest = arrayify(hashMessage(message));
+    const sig = await this._signer.signMessage(message);
+    const keyFromMessage = recoverPublicKey(message, sig);
+    const keyFromDigest = recoverPublicKey(digest, sig);
+    if (getAddress(this._address) === computeAddress(keyFromMessage)) {
+      this._publicKey = keyFromMessage;
+      this._isEthSigner = false;
+    } else if (getAddress(this._address) === computeAddress(keyFromDigest)) {
+      this._publicKey = keyFromDigest;
+      this._isEthSigner = true;
+    } else {
+      throw new Error(ERROR_MESSAGES.NON_ETH_SIGN_SIGNATURE);
+    }
+  }
 }