From cce3001d5d4f477643d25a7f3d300da94a5dbabf Mon Sep 17 00:00:00 2001
From: Patrick Griffis <pgriffis@igalia.com>
Date: Mon, 24 Mar 2025 11:01:54 -0500
Subject: [PATCH] threadedresolver: Cache network interface checks

---
 gio/gthreadedresolver.c | 62 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 55 insertions(+), 7 deletions(-)

diff --git a/gio/gthreadedresolver.c b/gio/gthreadedresolver.c
index e2e2d35d5..b7965c5d4 100644
--- a/gio/gthreadedresolver.c
+++ b/gio/gthreadedresolver.c
@@ -36,6 +36,7 @@
 #include "gcancellable.h"
 #include "ginetaddress.h"
 #include "ginetsocketaddress.h"
+#include "gnetworkmonitorbase.h"
 #include "gtask.h"
 #include "gsocketaddress.h"
 #include "gsrvtarget.h"
@@ -90,6 +91,11 @@ struct _GThreadedResolver
   GResolver parent_instance;
 
   GThreadPool *thread_pool;  /* (owned) */
+
+  GMutex interface_mutex;
+  GNetworkMonitor *network_monitor; /* (owned) */
+  gboolean monitor_supports_caching;
+  int network_is_loopback_only;
 };
 
 G_DEFINE_TYPE (GThreadedResolver, g_threaded_resolver, G_TYPE_RESOLVER)
@@ -110,6 +116,10 @@ g_threaded_resolver_init (GThreadedResolver *self)
                                               20,
                                               FALSE,
                                               NULL);
+
+  self->network_is_loopback_only = -1;
+
+  g_mutex_init (&self->interface_mutex);
 }
 
 static void
@@ -120,6 +130,12 @@ g_threaded_resolver_finalize (GObject *object)
   g_thread_pool_free (self->thread_pool, TRUE, FALSE);
   self->thread_pool = NULL;
 
+  if (self->network_monitor)
+    g_signal_handlers_disconnect_by_data (self->network_monitor, object);
+
+  g_clear_object (&self->network_monitor);
+  g_mutex_clear (&self->interface_mutex);
+
   G_OBJECT_CLASS (g_threaded_resolver_parent_class)->finalize (object);
 }
 
@@ -260,7 +276,7 @@ lookup_data_free (LookupData *data)
 }
 
 static gboolean
-only_has_loopback_interfaces (void)
+check_only_has_loopback_interfaces (void)
 {
 #if HAVE_GETIFADDRS
   struct ifaddrs *addrs;
@@ -305,12 +321,42 @@ only_has_loopback_interfaces (void)
 #endif
 }
 
+static void
+network_changed_cb (GNetworkMonitor   *monitor,
+                    gboolean           network_available,
+                    GThreadedResolver *resolver)
+{
+  g_mutex_lock (&resolver->interface_mutex);
+  resolver->network_is_loopback_only = -1;
+  g_mutex_unlock (&resolver->interface_mutex);
+}
+
+static gboolean
+only_has_loopback_interfaces_cached (GThreadedResolver *resolver)
+{
+  g_mutex_lock (&resolver->interface_mutex);
+
+  if (!resolver->network_monitor)
+    {
+      resolver->network_monitor = g_object_ref (g_network_monitor_get_default ());
+      resolver->monitor_supports_caching = G_TYPE_FROM_INSTANCE (resolver->network_monitor) != G_TYPE_NETWORK_MONITOR_BASE;
+      g_signal_connect_object (resolver->network_monitor, "network-changed", G_CALLBACK (network_changed_cb), resolver, G_CONNECT_DEFAULT);
+    }
+
+  if (!resolver->monitor_supports_caching || resolver->network_is_loopback_only == -1)
+    resolver->network_is_loopback_only = check_only_has_loopback_interfaces ();
+
+  g_mutex_unlock (&resolver->interface_mutex);
+
+  return resolver->network_is_loopback_only;
+}
 
 static GList *
-do_lookup_by_name (const gchar   *hostname,
-                   int            address_family,
-                   GCancellable  *cancellable,
-                   GError       **error)
+do_lookup_by_name (GThreadedResolver  *resolver,
+                   const gchar        *hostname,
+                   int                 address_family,
+                   GCancellable       *cancellable,
+                   GError            **error)
 {
   struct addrinfo *res = NULL;
   GList *addresses;
@@ -320,7 +366,7 @@ do_lookup_by_name (const gchar   *hostname,
   /* In general we only want IPs for valid interfaces.
    * However this will return nothing if you only have loopback interfaces.
    * Instead in this case we will manually filter out invalid IPs. */
-  gboolean only_loopback = only_has_loopback_interfaces ();
+  gboolean only_loopback = only_has_loopback_interfaces_cached (resolver);
 
 #ifdef AI_ADDRCONFIG
   if (!only_loopback)
@@ -1630,13 +1676,15 @@ threaded_resolver_worker_cb (gpointer task_data,
   GTask *task = G_TASK (g_steal_pointer (&task_data));
   LookupData *data = g_task_get_task_data (task);
   GCancellable *cancellable = g_task_get_cancellable (task);
+  GThreadedResolver *resolver = G_THREADED_RESOLVER (user_data);
   GError *local_error = NULL;
   gboolean should_return;
 
   switch (data->lookup_type) {
   case LOOKUP_BY_NAME:
     {
-      GList *addresses = do_lookup_by_name (data->lookup_by_name.hostname,
+      GList *addresses = do_lookup_by_name (resolver,
+                                            data->lookup_by_name.hostname,
                                             data->lookup_by_name.address_family,
                                             cancellable,
                                             &local_error);