From: Tom Yan Date: Wed, 8 Dec 2021 02:53:07 +0000 (+0800) Subject: resolved: filter stub listeners in manager_get_dns_server() X-Git-Tag: v250-rc3~38^2~2 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=af45251e4ce2ff48eb86769cccf48ffd51f49ce0;p=thirdparty%2Fsystemd.git resolved: filter stub listeners in manager_get_dns_server() Commit 49ef064c8dcd8ed12d98e6c705e676babade0897 attempts to handle "stub loop" by switching to the next server *after the query has been made*. The approach may be good enough for link scopes. However, for the manager / global scope, it is not. First of all, there are more than one types (SYSTEM and FALLBACK) of servers it can use. Also, whether those of type FALLBACK should be used depends. Besides, dns_scope_good_domain() determines whether things should be routed to a scope by checking whether the scope has a server. The decision made would be incorrect if stubs were not filtered beforehand. Therefore, to avoid failing query unnecessarily, and to make sure that extra stub listeners will not trigger unexpected and/or inconsistent behavior, make manager_get_dns_server() do what it should have done. --- diff --git a/src/resolve/resolved-dns-server.c b/src/resolve/resolved-dns-server.c index 7d180378b61..cd755b13d4c 100644 --- a/src/resolve/resolved-dns-server.c +++ b/src/resolve/resolved-dns-server.c @@ -875,9 +875,18 @@ DnsServer *manager_get_dns_server(Manager *m) { manager_read_resolv_conf(m); /* If no DNS server was chosen so far, pick the first one */ - if (!m->current_dns_server) + if (!m->current_dns_server || + /* In case m->current_dns_server != m->dns_servers */ + manager_server_is_stub(m, m->current_dns_server)) manager_set_dns_server(m, m->dns_servers); + while (m->current_dns_server && + manager_server_is_stub(m, m->current_dns_server)) { + manager_next_dns_server(m, NULL); + if (m->current_dns_server == m->dns_servers) + manager_set_dns_server(m, NULL); + } + if (!m->current_dns_server) { bool found = false;