From 7e46150a714f28cae12e4e9ee17e1f9d080600ba Mon Sep 17 00:00:00 2001
From: Linus Groh <mail@linusgroh.de>
Date: Thu, 13 Oct 2022 19:57:40 +0200
Subject: [PATCH] LibWeb: Implement 'Should response be blocked due to its MIME
 type?' AO

---
 Userland/Libraries/LibWeb/CMakeLists.txt      |  1 +
 .../Fetch/Infrastructure/MimeTypeBlocking.cpp | 37 +++++++++++++++++++
 .../Fetch/Infrastructure/MimeTypeBlocking.h   | 16 ++++++++
 3 files changed, 54 insertions(+)
 create mode 100644 Userland/Libraries/LibWeb/Fetch/Infrastructure/MimeTypeBlocking.cpp
 create mode 100644 Userland/Libraries/LibWeb/Fetch/Infrastructure/MimeTypeBlocking.h

diff --git a/Userland/Libraries/LibWeb/CMakeLists.txt b/Userland/Libraries/LibWeb/CMakeLists.txt
index 4ae2d2db43..5c639e6559 100644
--- a/Userland/Libraries/LibWeb/CMakeLists.txt
+++ b/Userland/Libraries/LibWeb/CMakeLists.txt
@@ -131,6 +131,7 @@ set(SOURCES
     Fetch/Infrastructure/HTTP/Requests.cpp
     Fetch/Infrastructure/HTTP/Responses.cpp
     Fetch/Infrastructure/HTTP/Statuses.cpp
+    Fetch/Infrastructure/MimeTypeBlocking.cpp
     Fetch/Infrastructure/PortBlocking.cpp
     Fetch/Infrastructure/URL.cpp
     Fetch/Request.cpp
diff --git a/Userland/Libraries/LibWeb/Fetch/Infrastructure/MimeTypeBlocking.cpp b/Userland/Libraries/LibWeb/Fetch/Infrastructure/MimeTypeBlocking.cpp
new file mode 100644
index 0000000000..e784bec07f
--- /dev/null
+++ b/Userland/Libraries/LibWeb/Fetch/Infrastructure/MimeTypeBlocking.cpp
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2022, Linus Groh <linusg@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/Fetch/Infrastructure/HTTP/Requests.h>
+#include <LibWeb/Fetch/Infrastructure/HTTP/Responses.h>
+#include <LibWeb/Fetch/Infrastructure/MimeTypeBlocking.h>
+
+namespace Web::Fetch::Infrastructure {
+
+// https://fetch.spec.whatwg.org/#ref-for-should-response-to-request-be-blocked-due-to-mime-type?
+RequestOrResponseBlocking should_response_to_request_be_blocked_due_to_its_mime_type(Response const& response, Request const& request)
+{
+    // 1. Let mimeType be the result of extracting a MIME type from response’s header list.
+    auto mime_type = response.header_list()->extract_mime_type();
+
+    // 2. If mimeType is failure, then return allowed.
+    if (!mime_type.has_value())
+        return RequestOrResponseBlocking::Allowed;
+
+    // 3. Let destination be request’s destination.
+    // 4. If destination is script-like and one of the following is true, then return blocked:
+    if (request.destination_is_script_like() && (
+            // - mimeType’s essence starts with "audio/", "image/", or "video/".
+            any_of(Array { "audio/"sv, "image/"sv, "video/"sv }, [&](auto prefix) { return mime_type->essence().starts_with(prefix); })
+            // - mimeType’s essence is "text/csv".
+            || mime_type->essence() == "text/csv"sv)) {
+        return RequestOrResponseBlocking::Blocked;
+    }
+
+    // 5. Return allowed.
+    return RequestOrResponseBlocking::Allowed;
+}
+
+}
diff --git a/Userland/Libraries/LibWeb/Fetch/Infrastructure/MimeTypeBlocking.h b/Userland/Libraries/LibWeb/Fetch/Infrastructure/MimeTypeBlocking.h
new file mode 100644
index 0000000000..96c81a1b97
--- /dev/null
+++ b/Userland/Libraries/LibWeb/Fetch/Infrastructure/MimeTypeBlocking.h
@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2022, Linus Groh <linusg@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/Fetch/Infrastructure/RequestOrResponseBlocking.h>
+#include <LibWeb/Forward.h>
+
+namespace Web::Fetch::Infrastructure {
+
+[[nodiscard]] RequestOrResponseBlocking should_response_to_request_be_blocked_due_to_its_mime_type(Response const&, Request const&);
+
+}