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network/dhcp4: send release message before stopping the client

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Otherwise, the socket is already closed and sending release will be
anyway skipped.

With this patch, release message is sent before stopping the client.
```
Jan 20 18:29:41 systemd[1]: Stopping systemd-networkd.service - Network Management...
Jan 20 18:29:41 systemd-networkd[3821255]: wlp59s0: DHCPv4 client: RELEASE
Jan 20 18:29:41 systemd-networkd[3821255]: wlp59s0: DHCPv4 client: STOPPED
Jan 20 18:29:41 systemd-networkd[3821255]: wlp59s0: DHCP lease lost
```

Fixes #39299.
This commit is contained in:
Yu Watanabe
2026-01-21 15:50:35 +01:00
committed by Zbigniew Jędrzejewski-Szmek
parent db4b6b7043
commit 68c7004236
3 changed files with 53 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/libsystemd-network/sd-dhcp-client.c
+25 -9
View File
@@ -103,6 +103,7 @@ struct sd_dhcp_client {
bool socket_priority_set;
bool ipv6_acquired;
bool bootp;
bool send_release;
};
static const uint8_t default_req_opts[] = {
@@ -663,6 +664,14 @@ int sd_dhcp_client_set_bootp(sd_dhcp_client *client, int bootp) {
return 0;
}
int sd_dhcp_client_set_send_release(sd_dhcp_client *client, int enable) {
assert_return(client, -EINVAL);
client->send_release = enable;
return 0;
}
static void client_set_state(sd_dhcp_client *client, DHCPState state) {
assert(client);
@@ -2347,13 +2356,18 @@ int sd_dhcp_client_start(sd_dhcp_client *client) {
return r;
}
int sd_dhcp_client_send_release(sd_dhcp_client *client) {
static int client_send_release(sd_dhcp_client *client) {
_cleanup_free_ DHCPPacket *release = NULL;
size_t optoffset, optlen;
int r;
if (!sd_dhcp_client_is_running(client) || !client->lease || client->bootp)
return 0; /* do nothing */
assert(client);
if (!client->send_release)
return 0; /* disabled */
if (!client->lease || client->bootp)
return 0; /* there is nothing to be released */
r = client_message_init(client, DHCP_RELEASE, &release, &optlen, &optoffset);
if (r < 0)
@@ -2377,12 +2391,7 @@ int sd_dhcp_client_send_release(sd_dhcp_client *client) {
return r;
log_dhcp_client(client, "RELEASE");
/* This function is mostly called when stopping daemon. Hence, do not call client_stop() or
* client_restart(). Otherwise, the notification callback will be called again and we may easily
* enter an infinite loop. */
client_initialize(client);
return 1; /* sent and stopped. */
return 0;
}
int sd_dhcp_client_send_decline(sd_dhcp_client *client) {
@@ -2425,11 +2434,18 @@ int sd_dhcp_client_send_decline(sd_dhcp_client *client) {
}
int sd_dhcp_client_stop(sd_dhcp_client *client) {
int r;
if (!client)
return 0;
DHCP_CLIENT_DONT_DESTROY(client);
r = client_send_release(client);
if (r < 0)
log_dhcp_client_errno(client, r,
"Failed to send DHCP release message, ignoring: %m");
client_stop(client, SD_DHCP_CLIENT_EVENT_STOP);
return 0;
src/network/networkd-dhcp4.c
+27 -22
View File
@@ -1206,14 +1206,6 @@ static int dhcp4_handler(sd_dhcp_client *client, int event, void *userdata) {
log_link_debug(link, "DHCP client is stopped. Acquiring IPv4 link-local address.");
if (link->dhcp_lease) {
if (link->network->dhcp_send_release) {
r = sd_dhcp_client_send_release(client);
if (r < 0)
log_link_full_errno(link,
ERRNO_IS_DISCONNECT(r) ? LOG_DEBUG : LOG_WARNING,
r, "Failed to send DHCP RELEASE, ignoring: %m");
}
r = dhcp4_lease_lost(link);
if (r < 0) {
link_enter_failed(link);
@@ -1503,6 +1495,11 @@ static int dhcp4_configure(Link *link) {
return log_link_debug_errno(link, r, "DHCPv4 CLIENT: Failed to %s BOOTP: %m",
enable_disable(link->network->dhcp_use_bootp));
r = sd_dhcp_client_set_send_release(link->dhcp_client, link->network->dhcp_send_release);
if (r < 0)
return log_link_debug_errno(link, r, "DHCPv4 CLIENT: Failed to %s sending release message on stop: %m",
enable_disable(link->network->dhcp_send_release));
r = sd_dhcp_client_attach_event(link->dhcp_client, link->manager->event, 0);
if (r < 0)
return log_link_debug_errno(link, r, "DHCPv4 CLIENT: Failed to attach event to DHCPv4 client: %m");
@@ -1865,8 +1862,27 @@ int link_request_dhcp4_client(Link *link) {
return 0;
}
static bool link_should_drop_dhcp4_config(Link *link, Network *network) {
assert(link);
assert(link->network);
if (!link_dhcp4_enabled(link))
/* DHCP client is now disabled. */
return true;
if (link->dhcp_client && link->network->dhcp_use_bootp &&
network && !network->dhcp_use_bootp && network->dhcp_send_release)
/* The client was enabled as a DHCP client and sending release message is requested, and now
* the client is enabled as a BOOTP client. In this case, we need to release the previous
* lease, and hence all DHCPv4 configurations (address, routes, DNS servers, and so on) needs
* to be dropped. */
return true;
return false;
}
int link_drop_dhcp4_config(Link *link, Network *network) {
int r, ret = 0;
int ret = 0;
assert(link);
assert(link->network);
@@ -1874,8 +1890,8 @@ int link_drop_dhcp4_config(Link *link, Network *network) {
if (link->network == network)
return 0; /* .network file is unchanged. It is not necessary to reconfigure the client. */
if (!link_dhcp4_enabled(link)) {
/* DHCP client is disabled. Stop the client if it is running and drop the lease. */
if (link_should_drop_dhcp4_config(link, network)) {
/* Stop the client if it is running and drop the lease. */
ret = sd_dhcp_client_stop(link->dhcp_client);
/* Also explicitly drop DHCPv4 address and routes. Why? This is for the case when the DHCPv4
@@ -1885,17 +1901,6 @@ int link_drop_dhcp4_config(Link *link, Network *network) {
RET_GATHER(ret, dhcp4_remove_address_and_routes(link, /* only_marked= */ false));
}
if (link->dhcp_client && link->network->dhcp_use_bootp &&
network && !network->dhcp_use_bootp && network->dhcp_send_release) {
/* If the client was enabled as a DHCP client, and is now enabled as a BOOTP client, release
* the previous lease. Note, this can be easily fail, e.g. when the interface is down. Hence,
* ignore any failures here. */
r = sd_dhcp_client_send_release(link->dhcp_client);
if (r < 0)
log_link_full_errno(link, ERRNO_IS_DISCONNECT(r) ? LOG_DEBUG : LOG_WARNING, r,
"Failed to send DHCP RELEASE, ignoring: %m");
}
/* Even if the client is currently enabled and also enabled in the new .network file, detailed
* settings for the client may be different. Let's unref() the client. But do not unref() the lease.
* it will be unref()ed later when a new lease is acquired. */
src/systemd/sd-dhcp-client.h
+1 -1
View File
@@ -148,6 +148,7 @@ int sd_dhcp_client_set_fallback_lease_lifetime(
int sd_dhcp_client_set_bootp(
sd_dhcp_client *client,
int bootp);
int sd_dhcp_client_set_send_release(sd_dhcp_client *client, int enable);
int sd_dhcp_client_add_option(sd_dhcp_client *client, sd_dhcp_option *v);
int sd_dhcp_client_add_vendor_option(sd_dhcp_client *client, sd_dhcp_option *v);
@@ -155,7 +156,6 @@ int sd_dhcp_client_add_vendor_option(sd_dhcp_client *client, sd_dhcp_option *v);
int sd_dhcp_client_is_running(sd_dhcp_client *client);
int sd_dhcp_client_stop(sd_dhcp_client *client);
int sd_dhcp_client_start(sd_dhcp_client *client);
int sd_dhcp_client_send_release(sd_dhcp_client *client);
int sd_dhcp_client_send_decline(sd_dhcp_client *client);
int sd_dhcp_client_send_renew(sd_dhcp_client *client);
int sd_dhcp_client_set_ipv6_connectivity(sd_dhcp_client *client, int have);