RequestServer: Remove headers exempted from storage from in-memory cache

We previously excluded headers exempted from storage when we serialized
the headers into the database. However, we stored the original headers
in-memory. So when a subsequent request hit CacheIndex::find_entry, we
would return an entry with response headers that should have been
excluded.

Author: trflynn89

Services/RequestServer/Cache/CacheIndex.cpp

@@ -18,9 +18,6 @@ static ByteString serialize_headers(HTTP::HeaderMap const& headers)
     StringBuilder builder;
 
     for (auto const& header : headers.headers()) {
-        if (is_header_exempted_from_storage(header.name))
-            continue;
-
         builder.append(header.name);
         builder.append(':');
         builder.append(header.value);
@@ -116,6 +113,15 @@ void CacheIndex::create_entry(u64 cache_key, String url, HTTP::HeaderMap respons
 {
     auto now = UnixDateTime::now();
 
+    for (size_t i = 0; i < response_headers.headers().size();) {
+        auto const& header = response_headers.headers()[i];
+
+        if (is_header_exempted_from_storage(header.name))
+            response_headers.remove(header.name);
+        else
+            ++i;
+    }
+
     Entry entry {
         .cache_key = cache_key,
         .url = move(url),