LookupServer: Use case-insensitive comparison for domain names

Some ISPs may MITM DNS requests coming from clients, changing the case
of domain name in response. LookupServer will refuse responses from
any DNS server in that case. This commit changes the behaviour to
perform a case-insensitive equality check.

Userland/Services/LookupServer/LookupServer.cpp

@@ -269,14 +269,14 @@ ErrorOr<Vector<DNSAnswer>> LookupServer::lookup(const DNSName& name, const Strin
         return Vector<DNSAnswer> {};
     }
 
-    // Verify the questions in our request and in their response match exactly, including case.
+    // Verify the questions in our request and in their response match, ignoring case.
     for (size_t i = 0; i < request.question_count(); ++i) {
         auto& request_question = request.questions()[i];
         auto& response_question = response.questions()[i];
-        bool exact_match = request_question.class_code() == response_question.class_code()
+        bool match = request_question.class_code() == response_question.class_code()
             && request_question.record_type() == response_question.record_type()
-            && request_question.name().as_string() == response_question.name().as_string();
-        if (!exact_match) {
+            && request_question.name().as_string().equals_ignoring_case(response_question.name().as_string());
+        if (!match) {
             dbgln("Request and response questions do not match");
             dbgln("   Request: name=_{}_, type={}, class={}", request_question.name().as_string(), response_question.record_type(), response_question.class_code());
             dbgln("  Response: name=_{}_, type={}, class={}", response_question.name().as_string(), response_question.record_type(), response_question.class_code());