LookupServer: Move case randomization into DNSName

* DNSName knows how to randomize itself
* DNSPacket no longer constructs DNSQuestion instances, it receives an already
  built DNSQuestion and just adds it to the list
* LookupServer::lookup() explicitly calls randomize_case() if it needs to
  randomize the case.

Userland/Services/LookupServer/DNSName.cpp

@@ -27,6 +27,7 @@
 
 #include "DNSName.h"
 #include <AK/Vector.h>
+#include <ctype.h>
 
 namespace LookupServer {
 
@@ -77,6 +78,22 @@ size_t DNSName::serialized_size() const
     return m_name.length() + 2;
 }
 
+void DNSName::randomize_case()
+{
+    StringBuilder builder;
+    for (char c : m_name) {
+        // Randomize the 0x20 bit in every ASCII character.
+        if (isalpha(c)) {
+            if (arc4random_uniform(2))
+                c |= 0x20;
+            else
+                c &= ~0x20;
+        }
+        builder.append(c);
+    }
+    m_name = builder.to_string();
+}
+
 OutputStream& operator<<(OutputStream& stream, const DNSName& name)
 {
     auto parts = name.as_string().split_view('.');

Userland/Services/LookupServer/DNSName.h

@@ -41,6 +41,8 @@ public:
     size_t serialized_size() const;
     const String& as_string() const { return m_name; }
 
+    void randomize_case();
+
 private:
     String m_name;
 };

Userland/Services/LookupServer/DNSPacket.cpp

@@ -37,29 +37,11 @@
 
 namespace LookupServer {
 
-void DNSPacket::add_question(const String& name, u16 record_type, ShouldRandomizeCase should_randomize_case)
+void DNSPacket::add_question(const DNSQuestion& question)
 {
+    m_questions.empend(question);
+
     ASSERT(m_questions.size() <= UINT16_MAX);
-
-    if (name.is_empty())
-        return;
-
-    StringBuilder builder;
-    for (size_t i = 0; i < name.length(); ++i) {
-        u8 ch = name[i];
-        if (should_randomize_case == ShouldRandomizeCase::Yes) {
-            // Randomize the 0x20 bit in every ASCII character.
-            if (isalpha(ch)) {
-                if (arc4random_uniform(2))
-                    ch |= 0x20;
-                else
-                    ch &= ~0x20;
-            }
-        }
-        builder.append(ch);
-    }
-
-    m_questions.empend(builder.to_string(), record_type, (u16)C_IN);
 }
 
 ByteBuffer DNSPacket::to_byte_buffer() const

Userland/Services/LookupServer/DNSPacket.h

@@ -79,7 +79,7 @@ public:
         return m_answers.size();
     }
 
-    void add_question(const String& name, u16 record_type, ShouldRandomizeCase);
+    void add_question(const DNSQuestion&);
 
     enum class Code : u8 {
         NOERROR = 0,

Userland/Services/LookupServer/LookupServer.cpp

@@ -172,7 +172,10 @@ Vector<String> LookupServer::lookup(const DNSName& name, const String& nameserve
     DNSPacket request;
     request.set_is_query();
     request.set_id(arc4random_uniform(UINT16_MAX));
-    request.add_question(name.as_string(), record_type, should_randomize_case);
+    DNSName name_in_question = name;
+    if (should_randomize_case == ShouldRandomizeCase::Yes)
+        name_in_question.randomize_case();
+    request.add_question({ name_in_question, record_type, C_IN });
 
     auto buffer = request.to_byte_buffer();