Add require statement to protect from returning an invalid value

wanseob · wanseob · commit acb3c723b2c2 · 2018-11-24T23:00:55.000+09:00
diff --git a/contracts/tree.sol b/contracts/tree.sol
@@ -88,10 +88,11 @@ library PartialMerkleTree {
         return getValue(tree, _findNode(tree, key));
     }
 
-    function safeGet(Tree storage tree, bytes key) internal view returns (bytes) {
+    function safeGet(Tree storage tree, bytes key) internal view returns (bytes value) {
         bytes32 valueHash = _findNode(tree, key);
         require(valueHash != bytes32(0));
-        return getValue(tree, valueHash);
+        value = getValue(tree, valueHash);
+        require(valueHash == keccak256(value));
     }
 
     function doesInclude(Tree storage tree, bytes key) internal view returns (bool) {

Original file line number	Diff line number	Diff line change
`@@ -88,10 +88,11 @@ library PartialMerkleTree {`
`88`	`88`	`return getValue(tree, _findNode(tree, key));`
`89`	`89`	`}`
`90`	`90`
`91`		`- function safeGet(Tree storage tree, bytes key) internal view returns (bytes) {`
	`91`	`+ function safeGet(Tree storage tree, bytes key) internal view returns (bytes value) {`
`92`	`92`	`bytes32 valueHash = _findNode(tree, key);`
`93`	`93`	`require(valueHash != bytes32(0));`
`94`		`- return getValue(tree, valueHash);`
	`94`	`+ value = getValue(tree, valueHash);`
	`95`	`+ require(valueHash == keccak256(value));`
`95`	`96`	`}`
`96`	`97`
`97`	`98`	`function doesInclude(Tree storage tree, bytes key) internal view returns (bool) {`