fix(cache): harden cache directive parsing

Signed-off-by: Matteo Collina <hello@matteocollina.com>

Author: mcollina

lib/cache/memory-cache-store.js

@@ -218,17 +218,62 @@ class MemoryCacheStore extends EventEmitter {
 }
 
 function findEntry (key, entries, now) {
-  return entries.find((entry) => (
-    entry.deleteAt > now &&
-    entry.method === key.method &&
-    (entry.vary == null || Object.keys(entry.vary).every(headerName => {
-      if (entry.vary[headerName] === null) {
-        return key.headers[headerName] === undefined
+  for (let i = 0; i < entries.length; i++) {
+    const entry = entries[i]
+    if (
+      entry.deleteAt > now &&
+      entry.method === key.method &&
+      varyMatches(key, entry)
+    ) {
+      return entry
+    }
+  }
+}
+
+function varyMatches (key, entry) {
+  if (entry.vary == null) {
+    return true
+  }
+
+  for (const headerName in entry.vary) {
+    if (Object.hasOwn(entry.vary, headerName) && !headerValueEquals(key.headers?.[headerName], entry.vary[headerName])) {
+      return false
+    }
+  }
+
+  return true
+}
+
+/**
+ * @param {string|string[]|null|undefined} lhs
+ * @param {string|string[]|null|undefined} rhs
+ * @returns {boolean}
+ */
+function headerValueEquals (lhs, rhs) {
+  if (lhs == null && rhs == null) {
+    return true
+  }
+
+  if ((lhs == null && rhs != null) ||
+      (lhs != null && rhs == null)) {
+    return false
+  }
+
+  if (Array.isArray(lhs) && Array.isArray(rhs)) {
+    if (lhs.length !== rhs.length) {
+      return false
+    }
+
+    for (let i = 0; i < lhs.length; i++) {
+      if (lhs[i] !== rhs[i]) {
+        return false
       }
+    }
+
+    return true
+  }
 
-      return entry.vary[headerName] === key.headers[headerName]
-    }))
-  ))
+  return lhs === rhs
 }
 
 module.exports = MemoryCacheStore

lib/cache/sqlite-cache-store.js

@@ -454,7 +454,13 @@ function headerValueEquals (lhs, rhs) {
       return false
     }
 
-    return lhs.every((x, i) => x === rhs[i])
+    for (let i = 0; i < lhs.length; i++) {
+      if (lhs[i] !== rhs[i]) {
+        return false
+      }
+    }
+
+    return true
   }
 
   return lhs === rhs