From c814ebae24d54577910e2e46a09d190c1632da56 Mon Sep 17 00:00:00 2001
From: Alex Miller <asmiller1989@gmail.com>
Date: Wed, 5 May 2021 16:50:31 -0500
Subject: [PATCH] Adds support for EIP712 edge cases

---
 package.json       |  2 +-
 src/ethereum.js    | 13 +++++++++++--
 test/testEthMsg.js | 41 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 3 deletions(-)

diff --git a/package.json b/package.json
index be5b65bf..0e7b16d3 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "gridplus-sdk",
-  "version": "0.7.12",
+  "version": "0.7.13",
   "description": "SDK to interact with GridPlus Lattice1 device",
   "scripts": {
     "commit": "git-cz",
diff --git a/src/ethereum.js b/src/ethereum.js
index f9f61fd8..78bb1ca2 100644
--- a/src/ethereum.js
+++ b/src/ethereum.js
@@ -606,6 +606,10 @@ function parseEIP712Item(data, type, isEthers=false) {
   } else if (type === 'address') {
     // Address must be a 20 byte buffer
     data = ensureHexBuffer(data);
+    // Edge case to handle the 0-address
+    if (data.length === 0) {
+      data = Buffer.alloc(20);
+    }
     if (data.length !== 20)
       throw new Error(`Address type must be 20 bytes, but got ${data.length} bytes`);
     // Ethers wants addresses as hex strings
@@ -615,10 +619,15 @@ function parseEIP712Item(data, type, isEthers=false) {
   } else if (type === 'uint8' || type === 'uint16' || type === 'uint32' || type === 'uint64') {
     data = parseInt(ensureHexBuffer(data).toString('hex'), 16)
   } else if (type === 'uint256') {
+    let b = ensureHexBuffer(data);
+    // Edge case to handle 0-value bignums
+    if (b.length === 0) {
+      b = Buffer.from('00', 'hex');
+    }
     // Uint256s should be encoded as bignums.
     if (isEthers === true) {
       // `ethers` uses their own BigNumber lib
-      data = ethers.BigNumber.from(`0x${ensureHexBuffer(data).toString('hex')}`)
+      data = ethers.BigNumber.from(`0x${b.toString('hex')}`)
     } else {
       // `bignumber.js` is needed for `cbor` encoding, which gets sent to the Lattice and plays
       // nicely with its firmware cbor lib.
@@ -628,7 +637,7 @@ function parseEIP712Item(data, type, isEthers=false) {
       // TODO: Find another cbor lib that is compataible with the firmware's lib in a browser
       // context. This is surprisingly difficult - I tried several libs and only cbor/borc have
       // worked (borc is a supposedly "browser compatible" version of cbor)
-      data = new cbor.Encoder().semanticTypes[1][0](ensureHexBuffer(data).toString('hex'), 16)
+      data = new cbor.Encoder().semanticTypes[1][0](b.toString('hex'), 16)
     }
   } else if (type === 'bool') {
     // Booleans need to be cast to a u8
diff --git a/test/testEthMsg.js b/test/testEthMsg.js
index 08ca31e1..4bcca45e 100644
--- a/test/testEthMsg.js
+++ b/test/testEthMsg.js
@@ -248,6 +248,47 @@ describe('Test ETH EIP712', function() {
     }
   })
 
+  it('Should test an example with 0 values', async () => {
+    const msg = {
+      'types': {
+        'EIP712Domain': [
+          { name: 'name', type: 'string' },
+          { name: 'host', type: 'string'},
+          { name: 'version', type: 'string' },
+          { name: 'chainId', type: 'uint256' },
+          { name: 'verifyingContract', type: 'address' },
+        ],
+        'Test': [
+          { name: 'owner', type: 'string' },
+        ]
+      },
+      'domain':{
+        name: 'Opensea on Matic',
+        verifyingContract: '0x0',
+        version: '1',
+        chainId: '',
+        host: '',
+      },
+      'primaryType': 'Test',
+      'message': {
+        'owner': '0x56626bd0d646ce9da4a12403b2c1ba00fb9e1c43',
+      }
+    }
+    const req = {
+      currency: 'ETH_MSG',
+      data: {
+        signerPath: [helpers.BTC_LEGACY_PURPOSE, helpers.ETH_COIN, HARDENED_OFFSET, 0, 0],
+        protocol: 'eip712',
+        payload: msg,
+      }
+    }
+    try {
+      await helpers.sign(client, req);
+    } catch (err) {
+      expect(err).to.equal(null)
+    }
+  })
+
   it('Should test canonical EIP712 example', async () => {   
     const msg = {
       types: {