core: save DHCP lease information in state file in /run

DHCP leases for a given interface are already exported on D-Bus
through DHCP4Config and DHCP6Config objects. It is useful to have the
same information also available on the filesystem so that it can be
easily used by scripts.

NM already saves some information about DHCP leases in /var, however
that directory can only be accessed by root, for good reasons.

Append lease options to the existing state file
/run/NetworkManager/devices/$ifindex. Contrary to /var this directory
is not persistent, but it seems more correct to expose the lease only
when it is active and not after it expired or after a reboot.

Since the file is in keyfile format, we add new [dhcp4] and [dhcp6]
sections; however, since some options have the same name for DHCPv4
and DHCPv6, we add a "dhcp4." or "dhcp6." prefix to make the parsing
by scripts (e.g. via "grep") easier.

The option name is the same we use on D-Bus. Since some DHCPv6 options
also have a "dhcp6_" prefix, the key name can contain "dhcp6" twice.

The new sections look like this:

  [dhcp4]
  dhcp4.broadcast_address=172.25.1.255
  dhcp4.dhcp_lease_time=120
  dhcp4.dhcp_server_identifier=172.25.1.4
  dhcp4.domain_name_servers=172.25.1.4
  dhcp4.domain_search=example.com
  dhcp4.expiry=1641214444
  dhcp4.ip_address=172.25.1.182
  dhcp4.next_server=172.25.1.4
  dhcp4.routers=172.25.1.4
  dhcp4.subnet_mask=255.255.255.0

  [dhcp6]
  dhcp6.dhcp6_name_servers=fd01::1
  dhcp6.dhcp6_ntp_servers=ntp.example.com
  dhcp6.ip6_address=fd01::1aa

5 files changed, 49 insertions, 24 deletions

diff --git a/NEWS b/NEWS
index 4bf6269ac8..9db05c5b7f 100644
--- a/NEWS
+++ b/NEWS
@@ -20,6 +20,9 @@ USE AT YOUR OWN RISK.  NOT RECOMMENDED FOR PRODUCTION USE!
 * Static IPv6 addresses from "ipv6.addresses" are now interpreted with
   first address being preferred. Their order got inverted. This is now
   consistent with IPv4.
+* The device state file /run/NetworkManager/devices/$ifindex now has
+  new sections [dhcp4] and [dhcp6] containing the DHCP options for the
+  current lease.
 
 =============================================
 NetworkManager-1.38
diff --git a/src/core/devices/nm-device.c b/src/core/devices/nm-device.c
index d1702f23a5..d77f3fa501 100644
--- a/src/core/devices/nm-device.c
+++ b/src/core/devices/nm-device.c
@@ -10064,6 +10064,7 @@ _dev_ipdhcpx_notify(NMDhcpClient *client, const NMDhcpClientNotifyData *notify_d
                                             FALSE);
 
         if (notify_data->lease_update.accepted) {
+            nm_manager_write_device_state(priv->manager, self, NULL);
             if (priv->ipdhcp_data_x[IS_IPv4].state != NM_DEVICE_IP_STATE_READY) {
                 _dev_ipdhcpx_set_state(self, addr_family, NM_DEVICE_IP_STATE_READY);
                 nm_dispatcher_call_device(NM_DISPATCHER_ACTION_DHCP_CHANGE_X(IS_IPv4),
diff --git a/src/core/nm-config.c b/src/core/nm-config.c
index ea1c2ab300..cdc070900f 100644
--- a/src/core/nm-config.c
+++ b/src/core/nm-config.c
@@ -11,7 +11,9 @@
 #include <stdio.h>
 
 #include "nm-utils.h"
+#include "nm-dhcp-config.h"
 #include "devices/nm-device.h"
+#include "dhcp/nm-dhcp-options.h"
 #include "NetworkManagerUtils.h"
 #include "libnm-core-intern/nm-core-internal.h"
 #include "libnm-core-intern/nm-keyfile-internal.h"
@@ -2573,13 +2575,16 @@ nm_config_device_state_write(int                            ifindex,
                              NMTernary                      nm_owned,
                              guint32                        route_metric_default_aspired,
                              guint32                        route_metric_default_effective,
-                             const char                    *next_server,
-                             const char                    *root_path,
-                             const char                    *dhcp_bootfile)
+                             NMDhcpConfig                  *dhcp4_config,
+                             NMDhcpConfig                  *dhcp6_config)
 {
     char    path[NM_STRLEN(NM_CONFIG_DEVICE_STATE_DIR "/") + DEVICE_STATE_FILENAME_LEN_MAX + 1];
-    GError *local                      = NULL;
-    nm_auto_unref_keyfile GKeyFile *kf = NULL;
+    GError *local                                 = NULL;
+    nm_auto_unref_keyfile GKeyFile *kf            = NULL;
+    const char                     *root_path     = NULL;
+    const char                     *next_server   = NULL;
+    const char                     *dhcp_bootfile = NULL;
+    int                             IS_IPv4;
 
     g_return_val_if_fail(ifindex > 0, FALSE);
     g_return_val_if_fail(!connection_uuid || *connection_uuid, FALSE);
@@ -2630,6 +2635,15 @@ nm_config_device_state_write(int                            ifindex,
                                  route_metric_default_aspired);
         }
     }
+
+    if (dhcp4_config) {
+        next_server   = nm_dhcp_config_get_option(dhcp4_config, "next_server");
+        root_path     = nm_dhcp_config_get_option(dhcp4_config, "root_path");
+        dhcp_bootfile = nm_dhcp_config_get_option(dhcp4_config, "filename");
+        if (!dhcp_bootfile)
+            dhcp_bootfile = nm_dhcp_config_get_option(dhcp4_config, "bootfile_name");
+    }
+
     if (next_server) {
         g_key_file_set_string(kf,
                               DEVICE_RUN_STATE_KEYFILE_GROUP_DEVICE,
@@ -2649,6 +2663,28 @@ nm_config_device_state_write(int                            ifindex,
                               dhcp_bootfile);
     }
 
+    for (IS_IPv4 = 1; IS_IPv4 >= 0; IS_IPv4--) {
+        NMDhcpConfig              *dhcp_config = IS_IPv4 ? dhcp4_config : dhcp6_config;
+        gs_free NMUtilsNamedValue *values      = NULL;
+        guint                      i;
+        guint                      num;
+
+        if (!dhcp_config)
+            continue;
+
+        values = nm_dhcp_config_get_option_values(dhcp_config, &num);
+        for (i = 0; i < num; i++) {
+            gs_free char *name_full = NULL;
+            const char   *prefix    = IS_IPv4 ? "dhcp4" : "dhcp6";
+
+            if (NM_STR_HAS_PREFIX(values[i].name, NM_DHCP_OPTION_REQPREFIX))
+                continue;
+
+            name_full = g_strdup_printf("%s.%s", prefix, values[i].name);
+            g_key_file_set_string(kf, prefix, name_full, values[i].value_str);
+        }
+    }
+
     if (!g_key_file_save_to_file(kf, path, &local)) {
         _LOGW("device-state: write #%d (%s) failed: %s", ifindex, path, local->message);
         g_error_free(local);
diff --git a/src/core/nm-config.h b/src/core/nm-config.h
index 2c23ff200e..d7498f92be 100644
--- a/src/core/nm-config.h
+++ b/src/core/nm-config.h
@@ -183,9 +183,8 @@ gboolean                 nm_config_device_state_write(int
                                                       NMTernary                      nm_owned,
                                                       guint32                        route_metric_default_aspired,
                                                       guint32                        route_metric_default_effective,
-                                                      const char                    *next_server,
-                                                      const char                    *root_path,
-                                                      const char                    *dhcp_bootfile);
+                                                      NMDhcpConfig                  *dhcp4_config,
+                                                      NMDhcpConfig                  *dhcp6_config);
 
 void nm_config_device_state_prune_stale(GHashTable *preserve_ifindexes,
                                         NMPlatform *preserve_in_platform);
diff --git a/src/core/nm-manager.c b/src/core/nm-manager.c
index 191d65bf65..ee661e499e 100644
--- a/src/core/nm-manager.c
+++ b/src/core/nm-manager.c
@@ -7039,10 +7039,6 @@ nm_manager_write_device_state(NMManager *self, NMDevice *device, int *out_ifinde
     guint32                        route_metric_default_aspired;
     guint32                        route_metric_default_effective;
     NMTernary                      nm_owned;
-    NMDhcpConfig                  *dhcp_config;
-    const char                    *next_server   = NULL;
-    const char                    *root_path     = NULL;
-    const char                    *dhcp_bootfile = NULL;
 
     NM_SET_OUT(out_ifindex, 0);
 
@@ -7084,15 +7080,6 @@ nm_manager_write_device_state(NMManager *self, NMDevice *device, int *out_ifinde
                                                               TRUE,
                                                               &route_metric_default_aspired);
 
-    dhcp_config = nm_device_get_dhcp_config(device, AF_INET);
-    if (dhcp_config) {
-        root_path     = nm_dhcp_config_get_option(dhcp_config, "root_path");
-        next_server   = nm_dhcp_config_get_option(dhcp_config, "next_server");
-        dhcp_bootfile = nm_dhcp_config_get_option(dhcp_config, "filename");
-        if (!dhcp_bootfile)
-            dhcp_bootfile = nm_dhcp_config_get_option(dhcp_config, "bootfile_name");
-    }
-
     if (!nm_config_device_state_write(ifindex,
                                       managed_type,
                                       perm_hw_addr_fake,
@@ -7100,9 +7087,8 @@ nm_manager_write_device_state(NMManager *self, NMDevice *device, int *out_ifinde
                                       nm_owned,
                                       route_metric_default_aspired,
                                       route_metric_default_effective,
-                                      next_server,
-                                      root_path,
-                                      dhcp_bootfile))
+                                      nm_device_get_dhcp_config(device, AF_INET),
+                                      nm_device_get_dhcp_config(device, AF_INET6)))
         return FALSE;
 
     NM_SET_OUT(out_ifindex, ifindex);