Merge pull request #3593 from ethereum/issue/3592

Fix param encoding for BN in arrays

CHANGELOG.md

@@ -237,3 +237,4 @@ Released with 1.0.0-beta.37 code base.
 
 - Extend `_txInputFormatter` with hex prefix check (#3317)
 - Extract revert reason string for geth >= 1.9.15 (#3520)
+- Incorrect param encoding of BN object in arrayed inputs (#3592)

packages/web3-eth-abi/src/index.js

@@ -109,11 +109,6 @@ ABICoder.prototype.encodeParameters = function (types, params) {
             type = type.type
         }
 
-        // Format BN to string
-        if (utils.isBN(param) || utils.isBigNumber(param)) {
-            return param.toString(10);
-        }
-
         param = self.formatParam(type, param)
 
         // Format params for tuples
@@ -252,6 +247,11 @@ ABICoder.prototype.formatParam = function (type, param) {
     const paramTypeNumber = new RegExp(/^(u?int)([0-9]*)$/);
     const paramTypeNumberArray = new RegExp(/^(u?int)([0-9]*)\[\]$/);
 
+    // Format BN to string
+    if (utils.isBN(param) || utils.isBigNumber(param)) {
+        return param.toString(10);
+    }
+
     if (type.match(paramTypeBytesArray) || type.match(paramTypeNumberArray)) {
         return param.map(p => this.formatParam(type.replace('[]', ''), p))
     }
@@ -285,9 +285,9 @@ ABICoder.prototype.formatParam = function (type, param) {
                 param = utils.rightPad(param, size * 2)
             }
         }
-        
+
         // format odd-length bytes to even-length
-        if (param.length % 2 === 1) { 
+        if (param.length % 2 === 1) {
             param = '0x0' + param.substring(2)
         }
     }

test/abi.encodeParameter.js

@@ -334,6 +334,35 @@ describe('lib/solidity/coder', function () {
             value: new BigNumber(42),
             expected: '000000000000000000000000000000000000000000000000000000000000002a'
         });
+        test({
+            type: 'uint256[]',
+            value: ['42'],
+            expected: '0000000000000000000000000000000000000000000000000000000000000020' +
+                      '0000000000000000000000000000000000000000000000000000000000000001' +
+                      '000000000000000000000000000000000000000000000000000000000000002a'
+        });
+        test({
+            type: 'uint256[]',
+            value: [new BN(42)],
+            expected: '0000000000000000000000000000000000000000000000000000000000000020' +
+                      '0000000000000000000000000000000000000000000000000000000000000001' +
+                      '000000000000000000000000000000000000000000000000000000000000002a'
+        });
+        test({
+            type: 'uint256[]',
+            value: [new BigNumber(42)],
+            expected: '0000000000000000000000000000000000000000000000000000000000000020' +
+                      '0000000000000000000000000000000000000000000000000000000000000001' +
+                      '000000000000000000000000000000000000000000000000000000000000002a'
+        });
+        test({
+            type: 'uint256[]',
+            value: [new BN(42), new BN(42)],
+            expected: '0000000000000000000000000000000000000000000000000000000000000020' +
+                      '0000000000000000000000000000000000000000000000000000000000000002' +
+                      '000000000000000000000000000000000000000000000000000000000000002a' +
+                      '000000000000000000000000000000000000000000000000000000000000002a'
+        });
     });
 });