Force close when dropping a client with a reset using SO_LINGER and give a warning on close failure

src/connector.c

@@ -155,6 +155,10 @@ static int drop_client(conn_instance_t *ci, client_instance_t *client)
 	ck_wlock(&ci->lock);
 	fd = client->fd;
 	if (fd != -1) {
+		const struct linger so_linger = { 1, 0 };
+
+		if (unlikely(setsockopt(client->fd, SOL_SOCKET, SO_LINGER, &so_linger, sizeof(so_linger))))
+			LOGWARNING("setsockopt failed with errno %d:%s", errno, strerror(errno));
 		Close(client->fd);
 		HASH_DEL(clients, client);
 		HASH_DELETE(fdhh, fdclients, client);

src/libckpool.c

@@ -437,7 +437,8 @@ void _Close(int *fd)
 	if (*fd < 0)
 		return;
 	LOGDEBUG("Closing file handle %d", *fd);
-	close(*fd);
+	if (unlikely(close(*fd)))
+		LOGWARNING("Close of fd %d failed with errno %d:%s", *fd, errno, strerror(errno));
 	*fd = -1;
 }