From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Fri, 13 Mar 2026 16:33:54 +0000 (+0900)
Subject: sd-dhcp-client: notify SD_DHCP_CLIENT_EVENT_EXPIRED only when we already have a bound... 
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2dff63a31ce33e4525f68351b47516a69b27334c;p=thirdparty%2Fsystemd.git

sd-dhcp-client: notify SD_DHCP_CLIENT_EVENT_EXPIRED only when we already have a bound lease

Otherwise, if we emit the notification without a valid bound lease, networkd
may be confused (of course should not, but for safety).

Also, increment the delay before calling client_start_delayed().
Otherwise, the first reboot is done instantaneously.
---

diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index f6ab4b34dfc..6ff6329ccf1 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -1328,6 +1328,34 @@ static int client_start(sd_dhcp_client *client) {
         return client_start_delayed(client);
 }
 
+static int client_restart(sd_dhcp_client *client) {
+        assert(client);
+        DHCP_CLIENT_DONT_DESTROY(client);
+
+        /* This is called when we receive a DHCPNAK or could not receive any replies. */
+
+        /* First, if we have a bound lease, then notify it is expired. */
+        if (IN_SET(client->state, DHCP_STATE_BOUND, DHCP_STATE_RENEWING, DHCP_STATE_REBINDING)) {
+                client_notify(client, SD_DHCP_CLIENT_EVENT_EXPIRED);
+
+                if (client->state == DHCP_STATE_STOPPED)
+                        return 0; /* The notify callback stopped the client. */
+        }
+
+        /* On reboot, DHCPNAK or no reply suggests that the network is changed or the address is already
+         * used by another host. Let's restart the client immediately without any delay to speed up the
+         * reboot process. */
+        if (client->state == DHCP_STATE_REBOOTING)
+                return client_start(client);
+
+        /* Otherwise, we should restart the client with a short delay. */
+        client->start_delay = CLAMP(client->start_delay * 2,
+                                    RESTART_AFTER_NAK_MIN_USEC, RESTART_AFTER_NAK_MAX_USEC);
+
+        log_dhcp_client(client, "REBOOT in %s", FORMAT_TIMESPAN(client->start_delay, USEC_PER_SEC));
+        return client_start_delayed(client);
+}
+
 static int client_timeout_expire(sd_event_source *s, uint64_t usec, void *userdata) {
         sd_dhcp_client *client = userdata;
         DHCP_CLIENT_DONT_DESTROY(client);
@@ -1775,23 +1803,6 @@ static int client_enter_bound(sd_dhcp_client *client, int notify_event) {
         return 0;
 }
 
-static int client_restart(sd_dhcp_client *client) {
-        int r;
-        assert(client);
-
-        client_notify(client, SD_DHCP_CLIENT_EVENT_EXPIRED);
-
-        r = client_start_delayed(client);
-        if (r < 0)
-                return r;
-
-        log_dhcp_client(client, "REBOOT in %s", FORMAT_TIMESPAN(client->start_delay, USEC_PER_SEC));
-
-        client->start_delay = CLAMP(client->start_delay * 2,
-                                    RESTART_AFTER_NAK_MIN_USEC, RESTART_AFTER_NAK_MAX_USEC);
-        return 0;
-}
-
 static int client_verify_message_header(sd_dhcp_client *client, DHCPMessage *message, size_t len) {
         const uint8_t *expected_chaddr = NULL;
         uint8_t expected_hlen = 0;