NetworkServer: Add a new NetworkServer service

This service is responsible for loading network configuration from a
/etc/Network.ini config file. It sets up static IP address + mask or
starts DHCPClient depending on configuration.

Base/etc/Network.ini

@@ -0,0 +1,5 @@
+[ep1s0]
+Enabled=false
+
+[ep0s8]
+DHCP=true

Base/etc/SystemServer.ini

@@ -51,6 +51,10 @@ SystemModes=text,graphical
 MultiInstance=true
 AcceptSocketConnections=true
 
+[NetworkServer]
+User=root
+SystemModes=text,graphical,self-test
+
 [LookupServer]
 Socket=/tmp/portal/lookup
 SocketPermissions=660
@@ -59,12 +63,6 @@ KeepAlive=true
 User=lookup
 SystemModes=text,graphical,self-test,generate-manpages
 
-[DHCPClient]
-Priority=low
-KeepAlive=true
-User=root
-SystemModes=text,graphical,self-test
-
 [NotificationServer]
 Socket=/tmp/portal/notify
 SocketPermissions=600

Userland/Services/CMakeLists.txt

@@ -13,6 +13,7 @@ add_subdirectory(KeyboardPreferenceLoader)
 add_subdirectory(LaunchServer)
 add_subdirectory(LoginServer)
 add_subdirectory(LookupServer)
+add_subdirectory(NetworkServer)
 add_subdirectory(NotificationServer)
 add_subdirectory(RequestServer)
 add_subdirectory(SQLServer)

Userland/Services/NetworkServer/CMakeLists.txt

@@ -0,0 +1,12 @@
+serenity_component(
+    NetworkServer
+    REQUIRED
+    TARGETS NetworkServer
+)
+
+set(SOURCES
+    main.cpp
+)
+
+serenity_bin(NetworkServer)
+target_link_libraries(NetworkServer LibCore LibConfig LibMain)

Userland/Services/NetworkServer/main.cpp

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2022, Maciej <sppmacd@pm.me>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/JsonArray.h>
+#include <AK/JsonObject.h>
+#include <AK/JsonParser.h>
+#include <LibCore/Command.h>
+#include <LibCore/ConfigFile.h>
+#include <LibCore/EventLoop.h>
+#include <LibCore/File.h>
+#include <LibCore/System.h>
+#include <LibMain/Main.h>
+#include <unistd.h>
+
+ErrorOr<int> serenity_main(Main::Arguments)
+{
+    TRY(Core::System::pledge("stdio recvfd sendfd rpath unix exec proc"));
+    TRY(Core::System::unveil("/proc/net", "r"));
+    TRY(Core::System::unveil("/bin/DHCPClient", "x"));
+    TRY(Core::System::unveil("/etc/Network.ini", "r"));
+    TRY(Core::System::unveil("/bin/ifconfig", "x"));
+    TRY(Core::System::unveil(nullptr, nullptr));
+
+    auto config_file = TRY(Core::ConfigFile::open_for_system("Network"));
+
+    // FIXME: Port this to Core::Stream when it gets read_all.
+    auto proc_net_adapters_file = TRY(Core::File::open("/proc/net/adapters", Core::OpenMode::ReadOnly));
+    auto data = proc_net_adapters_file->read_all();
+    JsonParser parser(data);
+    JsonValue proc_net_adapters_json = TRY(parser.parse());
+
+    auto groups = config_file->groups();
+    dbgln("Interfaces to configure: {}", groups);
+
+    struct InterfaceConfig {
+        bool enabled = false;
+        bool dhcp_enabled = false;
+        String ipv4_address = "0.0.0.0";
+        String ipv4_netmask = "0.0.0.0";
+    };
+
+    Vector<String> interfaces_with_dhcp_enabled;
+    proc_net_adapters_json.as_array().for_each([&](auto& value) {
+        auto& if_object = value.as_object();
+        auto ifname = if_object.get("name").to_string();
+
+        if (ifname == "loop")
+            return;
+
+        InterfaceConfig config;
+        if (!groups.contains_slow(ifname)) {
+            dbgln("Config for interface {} doesn't exist, not enabling it", ifname);
+        } else {
+            config.enabled = config_file->read_bool_entry(ifname, "Enabled", true);
+            config.dhcp_enabled = config_file->read_bool_entry(ifname, "DHCP", false);
+            if (!config.dhcp_enabled) {
+                config.ipv4_address = config_file->read_entry(ifname, "IPv4Address", "0.0.0.0");
+                config.ipv4_netmask = config_file->read_entry(ifname, "IPv4Netmask", "0.0.0.0");
+            }
+        }
+        if (config.enabled) {
+            if (config.dhcp_enabled)
+                interfaces_with_dhcp_enabled.append(ifname);
+            else {
+                // FIXME: Propagate errors
+                // FIXME: Do this asynchronously
+                dbgln("Setting up interface {} statically ({}/{})", ifname, config.ipv4_address, config.ipv4_netmask);
+                MUST(Core::command("ifconfig", { "-a", ifname.characters(), "-i", config.ipv4_address.characters(), "-m", config.ipv4_netmask.characters() }, {}));
+            }
+        }
+    });
+    if (!interfaces_with_dhcp_enabled.is_empty()) {
+        dbgln("Running DHCPClient for interfaces: {}", interfaces_with_dhcp_enabled);
+        Vector<char*> args;
+        char dhcp_client_arg[] = "DHCPClient";
+        args.append(dhcp_client_arg);
+        for (auto& iface : interfaces_with_dhcp_enabled)
+            args.append(const_cast<char*>(iface.characters()));
+        args.append(nullptr);
+        auto dhcp_client_pid = TRY(Core::System::posix_spawnp("DHCPClient", nullptr, nullptr, args.data(), environ));
+        TRY(Core::System::disown(dhcp_client_pid));
+    }
+    return 0;
+}