From 4f56cdc4b86d6e78a418d9a249d6bf27d2a66d7a Mon Sep 17 00:00:00 2001
From: Phan Shi Yu <phan_shi_yu@tech.gov.sg>
Date: Fri, 2 Aug 2024 13:25:59 +0800
Subject: [PATCH 1/2] fix: obfuscation of an array element can lead to
 undefined error

---
 src/4.0/obfuscate.ts          |  9 ++++++++-
 src/4.0/traverseAndFlatten.ts | 29 +++++++++++++++++++++++------
 2 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/src/4.0/obfuscate.ts b/src/4.0/obfuscate.ts
index a6519c3b..29876cb4 100644
--- a/src/4.0/obfuscate.ts
+++ b/src/4.0/obfuscate.ts
@@ -10,7 +10,14 @@ const obfuscate = (_data: V4WrappedDocument, fields: string[] | string) => {
 
   // fields to remove will contain the list of each expanded keys from the fields passed in parameter, it's for instance useful in case of
   // object obfuscation, where the object itself is not part of the salts, but each individual keys are
-  const toBeRemovedLeafNodes = traverseAndFlatten(pick(data, fieldsAsArray), ({ path }) => path);
+  const toBeRemovedLeafNodes = traverseAndFlatten(
+    pick(data, fieldsAsArray),
+    ({ path }) => path,
+    "",
+    // not picking from an array can lead to unpicked items being left as undefined
+    // these 'undefined' leaf nodes should be removed and not lead to an exception
+    true
+  );
   const salts = decodeSalt(data.proof.salts);
 
   const obfuscatedData = toBeRemovedLeafNodes.map((field) => {
diff --git a/src/4.0/traverseAndFlatten.ts b/src/4.0/traverseAndFlatten.ts
index 53a39f49..13aef690 100644
--- a/src/4.0/traverseAndFlatten.ts
+++ b/src/4.0/traverseAndFlatten.ts
@@ -1,9 +1,13 @@
 export type LeafValue = string | number | boolean | null | Record<string, never> | [];
 
+// we use a symbol just in case of conflicts with what the iteratee returns
+const undefinedSym = Symbol("undefined value that should be filtered away");
+
 function _traverseAndFlatten<IterateeValue>(
   data: unknown,
   iteratee: (data: { value: LeafValue; path: string }) => IterateeValue,
-  path = ""
+  path = "",
+  isRemoveUndefinedLeafNodes = false
 ): IterateeValue | IterateeValue[] {
   if (Array.isArray(data)) {
     // an empty array is considered a leaf node
@@ -13,7 +17,7 @@ function _traverseAndFlatten<IterateeValue>(
     const results: IterateeValue[] = [];
     for (let index = 0; index < data.length; index++) {
       const value = data[index];
-      const result = _traverseAndFlatten(value, iteratee, `${path}[${index}]`);
+      const result = _traverseAndFlatten(value, iteratee, `${path}[${index}]`, isRemoveUndefinedLeafNodes);
       if (Array.isArray(result)) {
         results.push(...result);
       } else {
@@ -29,7 +33,12 @@ function _traverseAndFlatten<IterateeValue>(
     // an empty object is considered a leaf node
     if (keys.length === 0) return iteratee({ value: {}, path });
     return Object.keys(data).flatMap((key) =>
-      _traverseAndFlatten(data[key as keyof typeof data], iteratee, path ? `${path}.${key}` : key)
+      _traverseAndFlatten(
+        data[key as keyof typeof data],
+        iteratee,
+        path ? `${path}.${key}` : key,
+        isRemoveUndefinedLeafNodes
+      )
     );
   }
 
@@ -37,6 +46,11 @@ function _traverseAndFlatten<IterateeValue>(
     return iteratee({ value: data, path });
   }
 
+  if (data === undefined && isRemoveUndefinedLeafNodes) {
+    // mark undefined leaf node with a unique symbol that must be removed later
+    return undefinedSym as IterateeValue;
+  }
+
   throw new Error(`Unexpected data '${data}' in '${path}'`);
 }
 
@@ -44,8 +58,11 @@ function _traverseAndFlatten<IterateeValue>(
 export function traverseAndFlatten<IterateeValue>(
   data: Record<string, unknown>,
   iteratee: (data: { value: LeafValue; path: string }) => IterateeValue,
-  path = ""
+  path = "",
+  /** by default throw when there are leaf nodes that are undefined, setting this to true will remove them instead */
+  isRemoveUndefinedLeafNodes = false
 ): IterateeValue[] {
-  const results = _traverseAndFlatten(data, iteratee, path);
-  return Array.isArray(results) ? results : [];
+  const results = _traverseAndFlatten(data, iteratee, path, isRemoveUndefinedLeafNodes);
+  // remove undefined leaf nodes
+  return Array.isArray(results) ? results.filter((v) => v !== undefinedSym) : [];
 }

From 371f73704c67c59f27bf14764832029bf35f8a9c Mon Sep 17 00:00:00 2001
From: Phan Shi Yu <phan_shi_yu@tech.gov.sg>
Date: Fri, 2 Aug 2024 13:39:05 +0800
Subject: [PATCH 2/2] fix: typo

---
 src/4.0/obfuscate.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/4.0/obfuscate.ts b/src/4.0/obfuscate.ts
index 29876cb4..54bf3843 100644
--- a/src/4.0/obfuscate.ts
+++ b/src/4.0/obfuscate.ts
@@ -14,7 +14,7 @@ const obfuscate = (_data: V4WrappedDocument, fields: string[] | string) => {
     pick(data, fieldsAsArray),
     ({ path }) => path,
     "",
-    // not picking from an array can lead to unpicked items being left as undefined
+    // picking from an array can lead to unpicked items being left as undefined
     // these 'undefined' leaf nodes should be removed and not lead to an exception
     true
   );