Userland+Meta: Add new helper program for network settings

This little program allows us to take the NetworkSettings app away
from being an elevated GUI app.

It receives a JsonObject on STDIN and writes it to the global
Network configuration file.

If the write was successfull it will apply the changes.

Meta/build-root-filesystem.sh

@@ -129,6 +129,11 @@ if [ -f mnt/boot/Kernel.debug ]; then
     chmod 0400 mnt/boot/Kernel.debug
 fi
 
+if [ -f mnt/bin/network-settings ]; then
+    chown 0:0 mnt/bin/network-settings
+    chmod 500 mnt/bin/network-settings
+fi
+
 chmod 600 mnt/etc/shadow
 chmod 755 mnt/res/devel/templates/*.postcreate
 echo "done"

Userland/Utilities/CMakeLists.txt

@@ -2,7 +2,7 @@ file(GLOB CMD_SOURCES  CONFIGURE_DEPENDS "*.cpp")
 list(APPEND SPECIAL_TARGETS test install)
 list(APPEND REQUIRED_TARGETS
     arp base64 basename cat chmod chown clear comm cp cut date dd df diff dirname dmesg du echo env expr false
-    file find grep groups head host hostname id ifconfig kill killall ln logout ls mkdir mount mv nproc
+    file find grep groups head host hostname id ifconfig kill killall ln logout ls mkdir mount mv network-settings nproc
     pgrep pidof ping pkill pmap ps readlink realpath reboot rm rmdir sed route seq shutdown sleep sort stat stty su tail test
     touch tr true umount uname uniq uptime w wc which whoami xargs yes
 )
@@ -115,6 +115,7 @@ target_link_libraries(markdown-check PRIVATE LibFileSystem LibMarkdown)
 target_link_libraries(matroska PRIVATE LibVideo)
 target_link_libraries(md PRIVATE LibMarkdown)
 target_link_libraries(mv PRIVATE LibFileSystem)
+target_link_libraries(network-settings PRIVATE LibCore LibMain)
 target_link_libraries(notify PRIVATE LibGfx LibGUI)
 target_link_libraries(open PRIVATE LibDesktop)
 target_link_libraries(passwd PRIVATE LibCrypt)

Userland/Utilities/network-settings.cpp

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2023, Fabian Dellwing <fabian@dellwing.net>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/JsonObject.h>
+#include <AK/JsonParser.h>
+#include <LibCore/ConfigFile.h>
+#include <LibCore/System.h>
+#include <LibMain/Main.h>
+#include <unistd.h>
+
+ErrorOr<int> serenity_main(Main::Arguments)
+{
+    TRY(Core::System::pledge("stdio rpath wpath cpath recvfd sendfd proc exec"));
+
+    TRY(Core::System::unveil("/bin/NetworkServer", "x"));
+    TRY(Core::System::unveil("/etc/Network.ini", "rwc"));
+    TRY(Core::System::unveil(nullptr, nullptr));
+
+    auto infile = TRY(Core::File::standard_input());
+
+    auto input_bytes = TRY(infile->read_until_eof());
+    StringView json_data = input_bytes;
+
+    if (json_data.is_empty() || json_data.is_whitespace())
+        return Error::from_errno(EINVAL);
+
+    auto json = TRY(JsonParser(json_data).parse());
+
+    if (!json.is_object())
+        return Error::from_errno(EINVAL);
+
+    auto json_object = json.as_object();
+
+    auto config_file = TRY(Core::ConfigFile::open_for_system("Network", Core::ConfigFile::AllowWriting::Yes));
+    json_object.for_each_member([&](DeprecatedString const& adapter_name, JsonValue const& adapter_data) {
+        adapter_data.as_object().for_each_member([&](const DeprecatedString& key, const JsonValue& value) {
+            switch (value.type()) {
+            case JsonValue::Type::String:
+                config_file->write_entry(adapter_name, key, value.as_string());
+                break;
+            case JsonValue::Type::Bool:
+                config_file->write_bool_entry(adapter_name, key, value.as_bool());
+                break;
+            case JsonValue::Type::Null:
+                break;
+            default:
+                dbgln("Extend switch/case key={}, value={}", key, value);
+                VERIFY_NOT_REACHED();
+            }
+        });
+    });
+    TRY(config_file->sync());
+
+    // FIXME: This should be done in a nicer way, but for that out NetworkServer implementation needs to actually be a server that we can talk to and not just a oneshot binary.
+    auto command = Vector<StringView>();
+    TRY(command.try_append("/bin/NetworkServer"sv));
+    TRY(Core::System::exec_command(command, true));
+
+    return 0;
+}