n-dhcp4: close packet socket after timeoutbg/n-dhcp4-packet-socket

In the DRAINING state we keep the packet socket alive until the next
I/O event, after the creation of the UDP socket. The goal is to avoid
missing packets when switching to the connected socket.

However, in normal conditions the next I/O event happens when the
address is renewed and therefore the packet socket stays around
unnecessarily for a long time.

Introduce a timeout of 10 seconds after which, without other events,
the packet socket gets closed.

2 files changed, 15 insertions, 1 deletions

diff --git a/src/n-dhcp4/src/n-dhcp4-c-connection.c b/src/n-dhcp4/src/n-dhcp4-c-connection.c
index 65328286e8..572801add1 100644
--- a/src/n-dhcp4/src/n-dhcp4-c-connection.c
+++ b/src/n-dhcp4/src/n-dhcp4-c-connection.c
@@ -175,6 +175,7 @@ int n_dhcp4_c_connection_listen(NDhcp4CConnection *connection) {
 
         connection->state = N_DHCP4_C_CONNECTION_STATE_PACKET;
         connection->fd_packet = fd_packet;
+        connection->ns_drain_timeout = 0;
         fd_packet = -1;
         return 0;
 }
@@ -211,6 +212,7 @@ int n_dhcp4_c_connection_connect(NDhcp4CConnection *connection,
         }
 
         connection->state = N_DHCP4_C_CONNECTION_STATE_DRAINING;
+        connection->ns_drain_timeout = n_dhcp4_gettime(CLOCK_BOOTTIME) + UINT64_C(10000000000);
         connection->fd_udp = fd_udp;
         fd_udp = -1;
         connection->client_ip = client->s_addr;
@@ -325,7 +327,7 @@ void n_dhcp4_c_connection_get_timeout(NDhcp4CConnection *connection,
         size_t n_send;
 
         if (!connection->request) {
-                *timeoutp = 0;
+                *timeoutp = connection->ns_drain_timeout;
                 return;
         }
 
@@ -369,6 +371,9 @@ void n_dhcp4_c_connection_get_timeout(NDhcp4CConnection *connection,
                 c_assert(0);
         }
 
+        if (connection->ns_drain_timeout != 0 && connection->ns_drain_timeout < timeout)
+            timeout = connection->ns_drain_timeout;
+
         *timeoutp = timeout;
 }
 
@@ -1122,6 +1127,13 @@ int n_dhcp4_c_connection_dispatch_timer(NDhcp4CConnection *connection,
         uint64_t timeout;
         int r;
 
+        if (connection->ns_drain_timeout != 0 && connection->ns_drain_timeout < timestamp) {
+                epoll_ctl(connection->fd_epoll, EPOLL_CTL_DEL, connection->fd_packet, NULL);
+                connection->fd_packet = c_close(connection->fd_packet);
+                connection->state = N_DHCP4_C_CONNECTION_STATE_UDP;
+                connection->ns_drain_timeout = 0;
+        }
+
         if (!connection->request)
                 return 0;
 
@@ -1189,6 +1201,7 @@ int n_dhcp4_c_connection_dispatch_io(NDhcp4CConnection *connection,
                 c_assert(!r);
                 connection->fd_packet = c_close(connection->fd_packet);
                 connection->state = N_DHCP4_C_CONNECTION_STATE_UDP;
+                connection->ns_drain_timeout = 0;
 
                 /* fall-through */
         case N_DHCP4_C_CONNECTION_STATE_UDP:
diff --git a/src/n-dhcp4/src/n-dhcp4-private.h b/src/n-dhcp4/src/n-dhcp4-private.h
index 6b366884be..8b17a1a25f 100644
--- a/src/n-dhcp4/src/n-dhcp4-private.h
+++ b/src/n-dhcp4/src/n-dhcp4-private.h
@@ -331,6 +331,7 @@ struct NDhcp4CConnection {
 
         NDhcp4Outgoing *request;        /* current request */
 
+        uint64_t ns_drain_timeout;      /* timeout for closing packet socket */
         uint32_t client_ip;             /* client IP address, or 0 */
         uint32_t server_ip;             /* server IP address, or 0 */
         uint16_t mtu;                   /* client mtu, or 0 */