Fixed long fixed-length bytes from overflowing encoded ABI. (#237)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ethers",
-  "version": "3.0.25",
+  "version": "3.0.26",
   "description": "Ethereum wallet library.",
   "main": "index.js",
   "scripts": {

tests/test-contract-interface.js

@@ -260,4 +260,15 @@ describe('Test Invalid Input', function() {
             return true;
         }, 'null bytes throws an error');
     });
+
+    it('fails to encode fixed bytes that are out of range', function() {
+        assert.throws(function() {
+            var result = coder.encode([ 'bytes32' ], [ '0x012345678901234567890123456789012345678901234567890123456789012345' ]);
+            console.log('Result', result);
+        }, function(error) {
+            assert.equal(error.reason, 'invalid bytes32 value', 'got invalid bytes32');
+            return true;
+        }, 'long bytes32 throws an error');
+    });
+
 });

utils/abi-coder.js

@@ -341,10 +341,11 @@ var coderNumber = function(coerceFunc, size, signed, localName) {
                 });
             }
             value = value.toTwos(size * 8).maskn(size * 8);
-            //value = value.toTwos(size * 8).maskn(size * 8);
+
             if (signed) {
                 value = value.fromTwos(size * 8).toTwos(256);
             }
+
             return utils.padZeros(utils.arrayify(value), 32);
         },
         decode: function(data, offset) {
@@ -412,6 +413,14 @@ var coderFixedBytes = function(coerceFunc, length, localName) {
         encode: function(value) {
             try {
                 value = utils.arrayify(value);
+
+                // @TODO: In next major change, the value.length MUST equal the
+                // length, but that is a backward-incompatible change, so here
+                // we just check for things that can cause problems.
+                if (value.length > 32) {
+                    throw new Error('too many bytes for field');
+                }
+
             } catch (error) {
                 errors.throwError('invalid ' + name + ' value', errors.INVALID_ARGUMENT, {
                     arg: localName,
@@ -419,7 +428,8 @@ var coderFixedBytes = function(coerceFunc, length, localName) {
                     value: error.value
                 });
             }
-            if (length === 32) { return value; }
+
+            if (value.length === 32) { return value; }
 
             var result = new Uint8Array(32);
             result.set(value);