1 files changed, 99 insertions, 0 deletions
diff --git a/Userland/Libraries/LibDNS/Name.cpp b/Userland/Libraries/LibDNS/Name.cpp
new file mode 100644
index 0000000000..e757ab0f44
--- /dev/null
+++ b/Userland/Libraries/LibDNS/Name.cpp
@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Sergey Bugaev <bugaevc@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "Name.h"
+#include <AK/Random.h>
+#include <AK/Vector.h>
+#include <ctype.h>
+
+namespace DNS {
+
+Name::Name(String const& name)
+{
+    if (name.ends_with('.'))
+        m_name = name.substring(0, name.length() - 1);
+    else
+        m_name = name;
+}
+
+Name Name::parse(u8 const* data, size_t& offset, size_t max_offset, size_t recursion_level)
+{
+    if (recursion_level > 4)
+        return {};
+
+    StringBuilder builder;
+    while (true) {
+        if (offset >= max_offset)
+            return {};
+        u8 b = data[offset++];
+        if (b == '\0') {
+            // This terminates the name.
+            return builder.to_string();
+        } else if ((b & 0xc0) == 0xc0) {
+            // The two bytes tell us the offset when to continue from.
+            if (offset >= max_offset)
+                return {};
+            size_t dummy = (b & 0x3f) << 8 | data[offset++];
+            auto rest_of_name = parse(data, dummy, max_offset, recursion_level + 1);
+            builder.append(rest_of_name.as_string());
+            return builder.to_string();
+        } else {
+            // This is the length of a part.
+            if (offset + b >= max_offset)
+                return {};
+            builder.append((char const*)&data[offset], (size_t)b);
+            builder.append('.');
+            offset += b;
+        }
+    }
+}
+
+size_t Name::serialized_size() const
+{
+    if (m_name.is_empty())
+        return 1;
+    return m_name.length() + 2;
+}
+
+void Name::randomize_case()
+{
+    StringBuilder builder;
+    for (char c : m_name) {
+        // Randomize the 0x20 bit in every ASCII character.
+        if (isalpha(c)) {
+            if (get_random_uniform(2))
+                c |= 0x20;
+            else
+                c &= ~0x20;
+        }
+        builder.append(c);
+    }
+    m_name = builder.to_string();
+}
+
+OutputStream& operator<<(OutputStream& stream, Name const& name)
+{
+    auto parts = name.as_string().split_view('.');
+    for (auto& part : parts) {
+        stream << (u8)part.length();
+        stream << part.bytes();
+    }
+    stream << '\0';
+    return stream;
+}
+
+unsigned Name::Traits::hash(Name const& name)
+{
+    return CaseInsensitiveStringTraits::hash(name.as_string());
+}
+
+bool Name::Traits::equals(Name const& a, Name const& b)
+{
+    return CaseInsensitiveStringTraits::equals(a.as_string(), b.as_string());
+}
+
+}