[PATCH 0/1] Enable Fallback DNS server when server is created

[PATCH 0/1] Enable Fallback DNS server when server is created

[Christophe Ronco]

I have a DHCP server that do not send DNS servers along with IP address.
I use the FallbackNameservers option in main.conf to handle this case.

After a board reboot or a connman restart, Fallback DNS servers are correctly
displayed in service properties but DNS requests still fail.
If I disconnect and reconnect the service, DNS requests are OK.

DNS requests fail because Fallback servers are not enabled.

They are not enabled because when dnsproxy_default_changed is called, DNS
servers are not created yet and enable_fallback does not do anything.
Then when servers are created in create_server (dnsproxy.c), they are not
enabled because they are fallback servers.

I made a patch to change the behavior in create_server and enable Fallback
server if there is no other DNS servers.

Best Regards,
Christophe Ronco

Christophe Ronco (1):
  dnsproxy: enable Fallback DNS server when created if needed

 src/dnsproxy.c | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

-- 
2.25.1

[PATCH 1/1] dnsproxy: enable Fallback DNS server when created if needed

[Christophe Ronco]

If there is no default DNS server when a fallback DNS server is created,
enable it.
---
 src/dnsproxy.c | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/src/dnsproxy.c b/src/dnsproxy.c
index 22730047..a810b676 100644
--- a/src/dnsproxy.c
+++ b/src/dnsproxy.c
@@ -2586,6 +2586,20 @@ static void enable_fallback(bool enable)
 	}
 }
 
+static unsigned int get_enabled_server_number(void)
+{
+	GSList *list;
+	unsigned int result = 0;
+
+	for (list = server_list; list; list = list->next) {
+		struct server_data *data = list->data;
+
+		if (data->index != -1 && data->enabled == true)
+			result++;
+	}
+	return result;
+}
+
 static struct server_data *create_server(int index,
 					const char *domain, const char *server,
 					int protocol)
@@ -2674,6 +2688,9 @@ static struct server_data *create_server(int index,
 			DBG("Adding DNS server %s", data->server);
 
 			enable_fallback(false);
+		} else if (data->index == -1 && get_enabled_server_number() == 0) {
+			data->enabled = true;
+			DBG("Adding fallback DNS server %s", data->server);
 		}
 
 		server_list = g_slist_append(server_list, data);
@@ -2834,7 +2851,6 @@ int __connman_dnsproxy_append(int index, const char *domain,
 static void remove_server(int index, const char *server, int protocol)
 {
 	struct server_data *data;
-	GSList *list;
 
 	data = find_server(index, server, protocol);
 	if (!data)
@@ -2842,14 +2858,8 @@ static void remove_server(int index, const char *server, int protocol)
 
 	destroy_server(data);
 
-	for (list = server_list; list; list = list->next) {
-		data = list->data;
-
-		if (data->index != -1 && data->enabled == true)
-			return;
-	}
-
-	enable_fallback(true);
+	if (get_enabled_server_number() == 0)
+		enable_fallback(true);
 }
 
 int __connman_dnsproxy_remove(int index, const char *domain,
-- 
2.25.1

Re: [PATCH 0/1] Enable Fallback DNS server when server is created

[Daniel Wagner]

Hi Christophe,

On Tue, Oct 11, 2022 at 11:56:40AM +0200, Christophe Ronco wrote:
> I have a DHCP server that do not send DNS servers along with IP address.
> I use the FallbackNameservers option in main.conf to handle this case.
> 
> After a board reboot or a connman restart, Fallback DNS servers are correctly
> displayed in service properties but DNS requests still fail.
> If I disconnect and reconnect the service, DNS requests are OK.
> 
> DNS requests fail because Fallback servers are not enabled.
> 
> They are not enabled because when dnsproxy_default_changed is called, DNS
> servers are not created yet and enable_fallback does not do anything.
> Then when servers are created in create_server (dnsproxy.c), they are not
> enabled because they are fallback servers.
> 
> I made a patch to change the behavior in create_server and enable Fallback
> server if there is no other DNS servers.

Patch applied. Thanks!
Daniel