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NetworkManager/SOURCES/1018-retry-hostname-resolution-when-it-fails-rhel-55397.patch

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From 8f5767448c3d1ab3748d1d4db98286254f7ad241 Mon Sep 17 00:00:00 2001
From: Beniamino Galvani <bgalvani@redhat.com>
Date: Wed, 31 Jul 2024 17:08:43 +0200
Subject: [PATCH] policy: retry hostname resolution when it fails
Currently if the system hostname can't be determined, NetworkManager
only retries when something changes: a new address is added, the DHCP
lease changes, etc.
However, it might happen that the current failure in looking up the
hostname is caused by an external factor, like a temporary outage of
the DNS server.
Add a mechanism to retry the resolution with an increasing timeout.
https://issues.redhat.com/browse/RHEL-17972
(cherry picked from commit 04ad4c86d0e943b1f39d059aafa0c690708293e8)
(cherry picked from commit 3555dbd2f2177fe9db9c016431e284d88e08d7cd)
(cherry picked from commit 7ae0f3edf06fffee0c642b09741c5df867c5bb10)
---
src/core/nm-policy.c | 139 ++++++++++++++++++++++++++++++++++++-------
1 file changed, 117 insertions(+), 22 deletions(-)
diff --git a/src/core/nm-policy.c b/src/core/nm-policy.c
index 9777cf326f..db588db7d6 100644
--- a/src/core/nm-policy.c
+++ b/src/core/nm-policy.c
@@ -48,6 +48,10 @@ NM_GOBJECT_PROPERTIES_DEFINE(NMPolicy,
PROP_ACTIVATING_IP4_AC,
PROP_ACTIVATING_IP6_AC, );
+#define HOSTNAME_RETRY_INTERVAL_MIN 30U
+#define HOSTNAME_RETRY_INTERVAL_MAX (60U * 60 * 12) /* 12 hours */
+#define HOSTNAME_RETRY_INTERVAL_MULTIPLIER 8U
+
typedef struct {
NMManager *manager;
NMNetns *netns;
@@ -79,14 +83,21 @@ typedef struct {
char *orig_hostname; /* hostname at NM start time */
char *cur_hostname; /* hostname we want to assign */
char *cur_hostname_full; /* similar to @last_hostname, but before shortening */
- char *
- last_hostname; /* last hostname NM set (to detect if someone else changed it in the meanwhile) */
+ char *last_hostname; /* last hostname NM set (to detect if someone else
+ * changed it in the meanwhile) */
+ struct {
+ GSource *source;
+ guint interval_sec;
+ gboolean do_restart; /* when something changes, set this to TRUE so that the next retry
+ * will restart from the lowest timeout. */
+ } hostname_retry;
bool changing_hostname : 1; /* hostname set operation in progress */
bool dhcp_hostname : 1; /* current hostname was set from dhcp */
bool updating_dns : 1;
GArray *ip6_prefix_delegations; /* pool of ip6 prefixes delegated to all devices */
+
} NMPolicyPrivate;
struct _NMPolicy {
@@ -135,9 +146,10 @@ _PRIV_TO_SELF(NMPolicyPrivate *priv)
/*****************************************************************************/
-static void update_system_hostname(NMPolicy *self, const char *msg);
-static void nm_policy_device_recheck_auto_activate_all_schedule(NMPolicy *self);
+static void update_system_hostname(NMPolicy *self, const char *msg, gboolean reset_retry_interval);
+static void nm_policy_device_recheck_auto_activate_all_schedule(NMPolicy *self);
static NMDevice *get_default_device(NMPolicy *self, int addr_family);
+static gboolean hostname_retry_cb(gpointer user_data);
/*****************************************************************************/
@@ -558,7 +570,56 @@ _get_hostname(NMPolicy *self)
}
static void
-_set_hostname(NMPolicy *self, const char *new_hostname, const char *msg)
+hostname_retry_schedule(NMPolicy *self)
+{
+ NMPolicyPrivate *priv = NM_POLICY_GET_PRIVATE(self);
+
+ if (priv->hostname_retry.source && !priv->hostname_retry.do_restart)
+ return;
+
+ nm_clear_g_source_inst(&priv->hostname_retry.source);
+
+ if (priv->hostname_retry.do_restart)
+ priv->hostname_retry.interval_sec = 0;
+
+ priv->hostname_retry.interval_sec *= HOSTNAME_RETRY_INTERVAL_MULTIPLIER;
+ priv->hostname_retry.interval_sec = NM_CLAMP(priv->hostname_retry.interval_sec,
+ HOSTNAME_RETRY_INTERVAL_MIN,
+ HOSTNAME_RETRY_INTERVAL_MAX);
+
+ _LOGT(LOGD_DNS,
+ "hostname-retry: schedule in %u seconds%s",
+ priv->hostname_retry.interval_sec,
+ priv->hostname_retry.do_restart ? " (restarted)" : "");
+ priv->hostname_retry.source =
+ nm_g_timeout_add_seconds_source(priv->hostname_retry.interval_sec, hostname_retry_cb, self);
+
+ priv->hostname_retry.do_restart = FALSE;
+}
+
+static gboolean
+hostname_retry_cb(gpointer user_data)
+{
+ NMPolicy *self = NM_POLICY(user_data);
+ NMPolicyPrivate *priv = NM_POLICY_GET_PRIVATE(self);
+ const CList *tmp_lst;
+ NMDevice *device;
+
+ _LOGT(LOGD_DNS, "hostname-retry: timeout");
+
+ nm_clear_g_source_inst(&priv->hostname_retry.source);
+
+ /* Clear any cached DNS results before retrying */
+ nm_manager_for_each_device (priv->manager, device, tmp_lst) {
+ nm_device_clear_dns_lookup_data(device, "hostname retry timeout");
+ }
+ update_system_hostname(self, "hostname retry timeout", FALSE);
+
+ return G_SOURCE_CONTINUE;
+}
+
+static void
+_set_hostname(NMPolicy *self, const char *new_hostname, const char *msg, gboolean do_retry)
{
NMPolicyPrivate *priv = NM_POLICY_GET_PRIVATE(self);
gs_free char *old_hostname = NULL;
@@ -612,6 +673,15 @@ _set_hostname(NMPolicy *self, const char *new_hostname, const char *msg)
priv->updating_dns = FALSE;
}
+ if (!do_retry) {
+ _LOGT(LOGD_DNS, "hostname-retry: clear");
+ nm_clear_g_source_inst(&priv->hostname_retry.source);
+ priv->hostname_retry.interval_sec = 0;
+ priv->hostname_retry.do_restart = FALSE;
+ } else if (!priv->hostname_retry.source) {
+ hostname_retry_schedule(self);
+ }
+
/* Finally, set kernel hostname */
nm_assert(!priv->cur_hostname || priv->cur_hostname[0]);
name = priv->cur_hostname ?: FALLBACK_HOSTNAME4;
@@ -797,7 +867,7 @@ device_dns_lookup_done(NMDevice *device, gpointer user_data)
g_signal_handlers_disconnect_by_func(device, device_dns_lookup_done, self);
- update_system_hostname(self, "lookup finished");
+ update_system_hostname(self, "lookup finished", FALSE);
}
static void
@@ -810,12 +880,28 @@ device_carrier_changed(NMDevice *device, GParamSpec *pspec, gpointer user_data)
if (nm_device_has_carrier(device)) {
g_signal_handlers_disconnect_by_func(device, device_carrier_changed, priv);
msg = g_strdup_printf("device '%s' got carrier", nm_device_get_iface(device));
- update_system_hostname(self, msg);
+ update_system_hostname(self, msg, TRUE);
}
}
+/*
+ * This function evaluates different sources (static configuration, DHCP, DNS, ...)
+ * to set the system hostname.
+ *
+ * When the function needs to perform a blocking action like a DNS resolution, it
+ * subscribes to a signal for the completion event, registering a callback that
+ * invokes this function again. In the new invocation, any previous DNS result is
+ * cached and doesn't need a new resolution.
+ *
+ * In case no hostname is found when after sources have been evaluated, it schedules
+ * a timer to retry later with an interval that is increased at each attempt. When
+ * this function is called after something changed (for example, carrier went up, a
+ * new address was added), @reset_retry_interval should be set to TRUE so that the
+ * next retry will use the smallest interval. In this way, it can quickly adapt to
+ * temporary misconfigurations at boot or when the network environment changes.
+ */
static void
-update_system_hostname(NMPolicy *self, const char *msg)
+update_system_hostname(NMPolicy *self, const char *msg, gboolean reset_retry_interval)
{
NMPolicyPrivate *priv = NM_POLICY_GET_PRIVATE(self);
const char *configured_hostname;
@@ -830,6 +916,9 @@ update_system_hostname(NMPolicy *self, const char *msg)
g_return_if_fail(self != NULL);
+ if (reset_retry_interval)
+ priv->hostname_retry.do_restart = TRUE;
+
if (priv->hostname_mode == NM_POLICY_HOSTNAME_MODE_NONE) {
_LOGT(LOGD_DNS, "set-hostname: hostname is unmanaged");
return;
@@ -872,7 +961,7 @@ update_system_hostname(NMPolicy *self, const char *msg)
/* Try a persistent hostname first */
configured_hostname = nm_hostname_manager_get_static_hostname(priv->hostname_manager);
if (configured_hostname && nm_utils_is_specific_hostname(configured_hostname)) {
- _set_hostname(self, configured_hostname, "from system configuration");
+ _set_hostname(self, configured_hostname, "from system configuration", FALSE);
priv->dhcp_hostname = FALSE;
return;
}
@@ -909,7 +998,10 @@ update_system_hostname(NMPolicy *self, const char *msg)
if (dhcp_hostname && dhcp_hostname[0]) {
p = nm_str_skip_leading_spaces(dhcp_hostname);
if (p[0]) {
- _set_hostname(self, p, info->IS_IPv4 ? "from DHCPv4" : "from DHCPv6");
+ _set_hostname(self,
+ p,
+ info->IS_IPv4 ? "from DHCPv4" : "from DHCPv6",
+ FALSE);
priv->dhcp_hostname = TRUE;
return;
}
@@ -937,7 +1029,7 @@ update_system_hostname(NMPolicy *self, const char *msg)
priv);
}
if (result) {
- _set_hostname(self, result, "from address lookup");
+ _set_hostname(self, result, "from address lookup", FALSE);
return;
}
if (wait) {
@@ -952,8 +1044,10 @@ update_system_hostname(NMPolicy *self, const char *msg)
}
/* If an hostname was set outside NetworkManager keep it */
- if (external_hostname)
+ if (external_hostname) {
+ hostname_retry_schedule(self);
return;
+ }
if (priv->hostname_mode == NM_POLICY_HOSTNAME_MODE_DHCP) {
/* In dhcp hostname-mode, the hostname is updated only if it comes from
@@ -962,7 +1056,7 @@ update_system_hostname(NMPolicy *self, const char *msg)
* so reset the hostname to the previous value
*/
if (priv->dhcp_hostname) {
- _set_hostname(self, priv->orig_hostname, "reset dhcp hostname");
+ _set_hostname(self, priv->orig_hostname, "reset dhcp hostname", TRUE);
priv->dhcp_hostname = FALSE;
}
return;
@@ -974,11 +1068,11 @@ update_system_hostname(NMPolicy *self, const char *msg)
* set externally to NM
*/
if (priv->orig_hostname) {
- _set_hostname(self, priv->orig_hostname, "from system startup");
+ _set_hostname(self, priv->orig_hostname, "from system startup", TRUE);
return;
}
- _set_hostname(self, NULL, "no hostname found");
+ _set_hostname(self, NULL, "no hostname found", TRUE);
}
static void
@@ -1255,7 +1349,7 @@ update_routing_and_dns(NMPolicy *self, gboolean force_update, NMDevice *changed_
update_ip6_routing(self, force_update);
/* Update the system hostname */
- update_system_hostname(self, "routing and dns");
+ update_system_hostname(self, "routing and dns", FALSE);
nm_dns_manager_end_updates(priv->dns_manager, __func__);
}
@@ -1572,7 +1666,7 @@ _static_hostname_changed_cb(NMHostnameManager *hostname_manager,
NMPolicyPrivate *priv = user_data;
NMPolicy *self = _PRIV_TO_SELF(priv);
- update_system_hostname(self, "hostname changed");
+ update_system_hostname(self, "hostname changed", FALSE);
}
void
@@ -2217,7 +2311,7 @@ device_state_changed(NMDevice *device,
update_ip_dns(self, AF_INET6, device);
update_ip4_routing(self, TRUE);
update_ip6_routing(self, TRUE);
- update_system_hostname(self, "routing and dns");
+ update_system_hostname(self, "routing and dns", TRUE);
nm_dns_manager_end_updates(priv->dns_manager, __func__);
break;
@@ -2365,7 +2459,7 @@ device_l3cd_changed(NMDevice *device,
update_ip6_routing(self, TRUE);
/* FIXME: since we already monitor platform addresses changes,
* this is probably no longer necessary? */
- update_system_hostname(self, "ip conf");
+ update_system_hostname(self, "ip conf", FALSE);
} else {
nm_dns_manager_set_ip_config(priv->dns_manager,
AF_UNSPEC,
@@ -2387,7 +2481,7 @@ device_platform_address_changed(NMDevice *device, gpointer user_data)
state = nm_device_get_state(device);
if (state > NM_DEVICE_STATE_DISCONNECTED && state < NM_DEVICE_STATE_DEACTIVATING) {
- update_system_hostname(self, "address changed");
+ update_system_hostname(self, "address changed", TRUE);
}
}
@@ -2726,7 +2820,7 @@ dns_config_changed(NMDnsManager *dns_manager, gpointer user_data)
nm_device_clear_dns_lookup_data(device, "DNS configuration changed");
}
- update_system_hostname(self, "DNS configuration changed");
+ update_system_hostname(self, "DNS configuration changed", FALSE);
}
nm_dispatcher_call_dns_change();
@@ -2997,7 +3091,7 @@ constructed(GObject *object)
G_OBJECT_CLASS(nm_policy_parent_class)->constructed(object);
_LOGD(LOGD_DNS, "hostname-mode: %s", _hostname_mode_to_string(priv->hostname_mode));
- update_system_hostname(self, "initial hostname");
+ update_system_hostname(self, "initial hostname", FALSE);
}
NMPolicy *
@@ -3055,6 +3149,7 @@ dispose(GObject *object)
nm_clear_g_source_inst(&priv->reset_connections_retries_idle_source);
nm_clear_g_source_inst(&priv->device_recheck_auto_activate_all_idle_source);
+ nm_clear_g_source_inst(&priv->hostname_retry.source);
nm_clear_g_free(&priv->orig_hostname);
nm_clear_g_free(&priv->cur_hostname);
--
2.46.0
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