diff --git a/src/resolve/resolved-dns-scope.c b/src/resolve/resolved-dns-scope.c index 40615ff605..e390715807 100644 --- a/src/resolve/resolved-dns-scope.c +++ b/src/resolve/resolved-dns-scope.c @@ -424,7 +424,15 @@ static int dns_scope_socket( return r; } - if (ifindex != 0) { + bool addr_is_nonlocal = s->link && + !manager_find_link_address(s->manager, sa.sa.sa_family, sockaddr_in_addr(&sa.sa)) && + in_addr_is_localhost(sa.sa.sa_family, sockaddr_in_addr(&sa.sa)) == 0; + + if (addr_is_nonlocal && ifindex != 0) { + /* As a special exception we don't use UNICAST_IF if we notice that the specified IP address + * is on the local host. Otherwise, destination addresses on the local host result in + * EHOSTUNREACH, since Linux won't send the packets out of the specified interface, but + * delivers them directly to the local socket. */ r = socket_set_unicast_if(fd, sa.sa.sa_family, ifindex); if (r < 0) return r; @@ -463,19 +471,13 @@ static int dns_scope_socket( else { bool bound = false; - /* Let's temporarily bind the socket to the specified ifindex. The kernel currently takes - * only the SO_BINDTODEVICE/SO_BINDTOINDEX ifindex into account when making routing decisions + /* Let's temporarily bind the socket to the specified ifindex. Older kernels only take + * the SO_BINDTODEVICE/SO_BINDTOINDEX ifindex into account when making routing decisions * in connect() — and not IP_UNICAST_IF. We don't really want any of the other semantics of * SO_BINDTODEVICE/SO_BINDTOINDEX, hence we immediately unbind the socket after the fact * again. - * - * As a special exception we don't do this if we notice that the specified IP address is on - * the local host. SO_BINDTODEVICE in combination with destination addresses on the local - * host result in EHOSTUNREACH, since Linux won't send the packets out of the specified - * interface, but delivers them directly to the local socket. */ - if (s->link && - !manager_find_link_address(s->manager, sa.sa.sa_family, sockaddr_in_addr(&sa.sa)) && - in_addr_is_localhost(sa.sa.sa_family, sockaddr_in_addr(&sa.sa)) == 0) { + */ + if (addr_is_nonlocal) { r = socket_bind_to_ifindex(fd, ifindex); if (r < 0) return r;