networkd: add basic Varlink interface

Let's get networkd onto Varlink. This only adds the most basic of
operations.

I'd love to see networkd do Varlink for all its basic operations so that
networkctl can use that, and work correctly before D-Bus is up. Right
now, many of networkctls calls simply don't work before D-Bus, and I'd
like to see that improved.

src/network/meson.build

@@ -56,8 +56,9 @@ sources = files(
         'networkd-link.c',
         'networkd-lldp-rx.c',
         'networkd-lldp-tx.c',
-        'networkd-manager-bus.c',
         'networkd-manager.c',
+        'networkd-manager-bus.c',
+        'networkd-manager-varlink.c',
         'networkd-ndisc.c',
         'networkd-neighbor.c',
         'networkd-netlabel.c',

src/network/networkd-manager-varlink.c

@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <unistd.h>
+
+#include "networkd-manager-varlink.h"
+#include "varlink.h"
+#include "varlink-io.systemd.Network.h"
+
+static int vl_method_get_states(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
+        Manager *m = ASSERT_PTR(userdata);
+
+        assert(link);
+
+        if (json_variant_elements(parameters) > 0)
+                return varlink_error_invalid_parameter(link, parameters);
+
+        return varlink_replyb(link,
+                              JSON_BUILD_OBJECT(
+                                              JSON_BUILD_PAIR_STRING("AddressState", link_address_state_to_string(m->address_state)),
+                                              JSON_BUILD_PAIR_STRING("IPv4AddressState", link_address_state_to_string(m->ipv4_address_state)),
+                                              JSON_BUILD_PAIR_STRING("IPv6AddressState", link_address_state_to_string(m->ipv6_address_state)),
+                                              JSON_BUILD_PAIR_STRING("CarrierState", link_carrier_state_to_string(m->carrier_state)),
+                                              JSON_BUILD_PAIR_CONDITION(m->online_state >= 0, "OnlineState", JSON_BUILD_STRING(link_online_state_to_string(m->online_state))),
+                                              JSON_BUILD_PAIR_STRING("OperationalState", link_operstate_to_string(m->operational_state))));
+}
+
+static int vl_method_get_namespace_id(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
+        uint64_t id;
+
+        assert(link);
+
+        if (json_variant_elements(parameters) > 0)
+                return varlink_error_invalid_parameter(link, parameters);
+
+        struct stat st;
+        if (stat("/proc/self/ns/net", &st) < 0) {
+                log_warning_errno(errno, "Failed to stat network namespace, ignoring: %m");
+                id = 0;
+        } else
+                id = st.st_ino;
+
+        return varlink_replyb(link,
+                              JSON_BUILD_OBJECT(
+                                              JSON_BUILD_PAIR_UNSIGNED("NamespaceId", id)));
+}
+
+int manager_connect_varlink(Manager *m) {
+        _cleanup_(varlink_server_unrefp) VarlinkServer *s = NULL;
+        int r;
+
+        assert(m);
+
+        if (m->varlink_server)
+                return 0;
+
+        r = varlink_server_new(&s, VARLINK_SERVER_ACCOUNT_UID|VARLINK_SERVER_INHERIT_USERDATA);
+        if (r < 0)
+                return log_error_errno(r, "Failed to allocate varlink server object: %m");
+
+        varlink_server_set_userdata(s, m);
+
+        r = varlink_server_add_interface(s, &vl_interface_io_systemd_Network);
+        if (r < 0)
+                return log_error_errno(r, "Failed to add Network interface to varlink server: %m");
+
+        r = varlink_server_bind_method_many(
+                        s,
+                        "io.systemd.Network.GetStates", vl_method_get_states,
+                        "io.systemd.Network.GetNamespaceId", vl_method_get_namespace_id);
+        if (r < 0)
+                return log_error_errno(r, "Failed to register varlink methods: %m");
+
+        r = varlink_server_listen_address(s, "/run/systemd/netif/io.systemd.Network", 0666);
+        if (r < 0)
+                return log_error_errno(r, "Failed to bind to varlink socket: %m");
+
+        r = varlink_server_attach_event(s, m->event, SD_EVENT_PRIORITY_NORMAL);
+        if (r < 0)
+                return log_error_errno(r, "Failed to attach varlink connection to event loop: %m");
+
+        m->varlink_server = TAKE_PTR(s);
+        return 0;
+}
+
+void manager_varlink_done(Manager *m) {
+        assert(m);
+
+        m->varlink_server = varlink_server_unref(m->varlink_server);
+        (void) unlink("/run/systemd/netif/io.systemd.Network");
+}

src/network/networkd-manager-varlink.h

@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include "networkd-manager.h"
+
+int manager_connect_varlink(Manager *m);
+void manager_varlink_done(Manager *m);

src/network/networkd-manager.c

@@ -36,8 +36,9 @@
 #include "networkd-dhcp-server-bus.h"
 #include "networkd-dhcp6.h"
 #include "networkd-link-bus.h"
-#include "networkd-manager-bus.h"
 #include "networkd-manager.h"
+#include "networkd-manager-bus.h"
+#include "networkd-manager-varlink.h"
 #include "networkd-neighbor.h"
 #include "networkd-network-bus.h"
 #include "networkd-nexthop.h"
@@ -529,6 +530,10 @@ int manager_setup(Manager *m) {
         if (m->test_mode)
                 return 0;
 
+        r = manager_connect_varlink(m);
+        if (r < 0)
+                return r;
+
         r = manager_connect_bus(m);
         if (r < 0)
                 return r;
@@ -640,6 +645,8 @@ Manager* manager_free(Manager *m) {
 
         sd_device_monitor_unref(m->device_monitor);
 
+        manager_varlink_done(m);
+
         bus_verify_polkit_async_registry_free(m->polkit_registry);
         sd_bus_flush_close_unref(m->bus);
 

src/network/networkd-manager.h

@@ -17,6 +17,7 @@
 #include "ordered-set.h"
 #include "set.h"
 #include "time-util.h"
+#include "varlink.h"
 
 struct Manager {
         sd_netlink *rtnl;
@@ -25,6 +26,7 @@ struct Manager {
         sd_event *event;
         sd_resolve *resolve;
         sd_bus *bus;
+        VarlinkServer *varlink_server;
         sd_device_monitor *device_monitor;
         Hashmap *polkit_registry;
         int ethtool_fd;

src/shared/meson.build

@@ -176,9 +176,10 @@ shared_sources = files(
         'varlink-io.systemd.Credentials.c',
         'varlink-io.systemd.Journal.c',
         'varlink-io.systemd.ManagedOOM.c',
+        'varlink-io.systemd.Network.c',
         'varlink-io.systemd.PCRExtend.c',
-        'varlink-io.systemd.Resolve.Monitor.c',
         'varlink-io.systemd.Resolve.c',
+        'varlink-io.systemd.Resolve.Monitor.c',
         'varlink-io.systemd.UserDatabase.c',
         'varlink-io.systemd.oom.c',
         'varlink-io.systemd.service.c',

src/shared/varlink-io.systemd.Network.c

@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "varlink-io.systemd.Network.h"
+
+static VARLINK_DEFINE_METHOD(GetStates,
+                             VARLINK_DEFINE_OUTPUT(AddressState, VARLINK_STRING, 0),
+                             VARLINK_DEFINE_OUTPUT(IPv4AddressState, VARLINK_STRING, 0),
+                             VARLINK_DEFINE_OUTPUT(IPv6AddressState, VARLINK_STRING, 0),
+                             VARLINK_DEFINE_OUTPUT(CarrierState, VARLINK_STRING, 0),
+                             VARLINK_DEFINE_OUTPUT(OnlineState, VARLINK_STRING, 0),
+                             VARLINK_DEFINE_OUTPUT(OperationalState, VARLINK_STRING, 0));
+
+static VARLINK_DEFINE_METHOD(GetNamespaceId,
+                             VARLINK_DEFINE_OUTPUT(NamespaceId, VARLINK_INT, 0));
+
+VARLINK_DEFINE_INTERFACE(
+                io_systemd_Network,
+                "io.systemd.Network",
+                &vl_method_GetStates,
+                &vl_method_GetNamespaceId);

src/shared/varlink-io.systemd.Network.h

@@ -0,0 +1,6 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include "varlink-idl.h"
+
+extern const VarlinkInterface vl_interface_io_systemd_Network;

src/test/test-varlink-idl.c

@@ -11,6 +11,7 @@
 #include "varlink-io.systemd.Credentials.h"
 #include "varlink-io.systemd.Journal.h"
 #include "varlink-io.systemd.ManagedOOM.h"
+#include "varlink-io.systemd.Network.h"
 #include "varlink-io.systemd.PCRExtend.h"
 #include "varlink-io.systemd.Resolve.Monitor.h"
 #include "varlink-io.systemd.Resolve.h"
@@ -134,6 +135,8 @@ TEST(parse_format) {
         print_separator();
         test_parse_format_one(&vl_interface_io_systemd_ManagedOOM);
         print_separator();
+        test_parse_format_one(&vl_interface_io_systemd_Network);
+        print_separator();
         test_parse_format_one(&vl_interface_io_systemd_oom);
         print_separator();
         test_parse_format_one(&vl_interface_io_systemd);