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dns-manager: prevent DNS plugins from respawning too quickly

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If dnsmasq (or another DNS plugin) exits immediately (for example due
to an already used port), the DNS manager keeps restarting it forever,
wasting system resources and filling logs.

Add a simple rate-limiting mechanism.

https://bugzilla.gnome.org/show_bug.cgi?id=760691
This commit is contained in:
Beniamino Galvani
2016-01-15 15:04:39 +01:00
parent ec1185d6dd
commit 64ac910131
2 changed files with 46 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

50
src/dns-manager/nm-dns-manager.c
View File

@@ -82,6 +82,10 @@ G_DEFINE_TYPE (NMDnsManager, nm_dns_manager, G_TYPE_OBJECT)
#define NETCONFIG_PATH "/sbin/netconfig"
#endif
#define PLUGIN_RATELIMIT_INTERVAL 30
#define PLUGIN_RATELIMIT_BURST 5
#define PLUGIN_RATELIMIT_DELAY 300
NM_DEFINE_SINGLETON_INSTANCE (NMDnsManager);
/*********************************************************************************************/
@@ -130,6 +134,12 @@ typedef struct {
NMConfig *config;
gboolean dns_touched;
struct {
guint64 ts;
guint num_restarts;
guint timer;
} plugin_ratelimit;
} NMDnsManagerPrivate;
enum {
@@ -799,6 +809,7 @@ update_dns (NMDnsManager *self,
g_return_val_if_fail (!error || !*error, FALSE);
priv = NM_DNS_MANAGER_GET_PRIVATE (self);
nm_clear_g_source (&priv->plugin_ratelimit.timer);
if (priv->resolv_conf_mode == NM_DNS_MANAGER_RESOLV_CONF_UNMANAGED) {
update = FALSE;
@@ -1022,20 +1033,47 @@ plugin_failed (NMDnsPlugin *plugin, gpointer user_data)
}
}
static void
plugin_child_quit (NMDnsPlugin *plugin, int exit_status, gpointer user_data)
static gboolean
plugin_child_quit_update_dns (gpointer user_data)
{
NMDnsManager *self = NM_DNS_MANAGER (user_data);
GError *error = NULL;
_LOGW ("plugin %s child quit unexpectedly; refreshing DNS",
nm_dns_plugin_get_name (plugin));
NMDnsManager *self = NM_DNS_MANAGER (user_data);
/* Let the plugin try to spawn the child again */
if (!update_dns (self, FALSE, &error)) {
_LOGW ("could not commit DNS changes: %s", error->message);
g_clear_error (&error);
}
return G_SOURCE_REMOVE;
}
static void
plugin_child_quit (NMDnsPlugin *plugin, int exit_status, gpointer user_data)
{
NMDnsManager *self = NM_DNS_MANAGER (user_data);
NMDnsManagerPrivate *priv = NM_DNS_MANAGER_GET_PRIVATE (self);
gint64 ts = nm_utils_get_monotonic_timestamp_ms ();
_LOGW ("plugin %s child quit unexpectedly", nm_dns_plugin_get_name (plugin));
if ( !priv->plugin_ratelimit.ts
|| (ts - priv->plugin_ratelimit.ts) / 1000 > PLUGIN_RATELIMIT_INTERVAL) {
priv->plugin_ratelimit.ts = ts;
priv->plugin_ratelimit.num_restarts = 0;
} else {
priv->plugin_ratelimit.num_restarts++;
if (priv->plugin_ratelimit.num_restarts > PLUGIN_RATELIMIT_BURST) {
_LOGW ("plugin %s child respawning too fast, delaying update for %u seconds",
nm_dns_plugin_get_name (plugin), PLUGIN_RATELIMIT_DELAY);
priv->plugin_ratelimit.timer = g_timeout_add_seconds (PLUGIN_RATELIMIT_DELAY,
plugin_child_quit_update_dns,
self);
return;
}
}
plugin_child_quit_update_dns (self);
}
gboolean

3
src/dns-manager/nm-dns-plugin.c
View File

@@ -33,7 +33,7 @@ typedef struct {
gboolean disposed;
GPid pid;
guint32 watch_id;
guint watch_id;
char *progname;
char *pidfile;
} NMDnsPluginPrivate;
@@ -130,6 +130,7 @@ watch_cb (GPid pid, gint status, gpointer user_data)
NMDnsPluginPrivate *priv = NM_DNS_PLUGIN_GET_PRIVATE (self);
priv->pid = 0;
priv->watch_id = 0;
g_free (priv->progname);
priv->progname = NULL;