89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen#include "alloc-util.h"

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen#include "resolved-dns-server.h"

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen#include "resolved-resolv-conf.h"

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen#include "siphash24.h"

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen#include "string-table.h"

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen#include "string-util.h"

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen#define DNS_TIMEOUT_MIN_USEC (500 * USEC_PER_MSEC)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen#define DNS_TIMEOUT_MAX_USEC (5 * USEC_PER_SEC)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen#define DNS_SERVER_FEATURE_GRACE_PERIOD_MAX_USEC (6 * USEC_PER_HOUR)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen#define DNS_SERVER_FEATURE_GRACE_PERIOD_MIN_USEC (5 * USEC_PER_MINUTE)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen#define DNS_SERVER_FEATURE_RETRY_ATTEMPTS 3

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersenint dns_server_new(

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen Manager *m,

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen DnsServer **ret,

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen DnsServerType type,

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen Link *l,

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen int family,

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen const union in_addr_union *in_addr) {

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen DnsServer *s;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert(m);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert((type == DNS_SERVER_LINK) == !!l);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert(in_addr);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (!IN_SET(family, AF_INET, AF_INET6))

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen return -EAFNOSUPPORT;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (l) {

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (l->n_dns_servers >= LINK_DNS_SERVERS_MAX)

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen return -E2BIG;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen } else {

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (m->n_dns_servers >= MANAGER_DNS_SERVERS_MAX)

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen return -E2BIG;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen }

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s = new0(DnsServer, 1);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (!s)

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen return -ENOMEM;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->n_ref = 1;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->manager = m;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->verified_features = _DNS_SERVER_FEATURE_LEVEL_INVALID;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->possible_features = DNS_SERVER_FEATURE_LEVEL_BEST;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->features_grace_period_usec = DNS_SERVER_FEATURE_GRACE_PERIOD_MIN_USEC;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->received_udp_packet_max = DNS_PACKET_UNICAST_SIZE_MAX;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->type = type;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->family = family;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->address = *in_addr;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->resend_timeout = DNS_TIMEOUT_MIN_USEC;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen switch (type) {

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen case DNS_SERVER_LINK:

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->link = l;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_APPEND(servers, l->dns_servers, s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen l->n_dns_servers++;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen break;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen case DNS_SERVER_SYSTEM:

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_APPEND(servers, m->dns_servers, s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen m->n_dns_servers++;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen break;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen case DNS_SERVER_FALLBACK:

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_APPEND(servers, m->fallback_dns_servers, s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen m->n_dns_servers++;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen break;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen default:

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert_not_reached("Unknown server type");

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen }

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->linked = true;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen /* A new DNS server that isn't fallback is added and the one

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen if (type != DNS_SERVER_FALLBACK &&

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen m->current_dns_server &&

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen m->current_dns_server->type == DNS_SERVER_FALLBACK)

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen manager_set_dns_server(m, NULL);

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen if (ret)

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen *ret = s;

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen return 0;

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen}

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen

b95cc756de7a27f7546e42dd9acf6da0669da402Tom GundersenDnsServer* dns_server_ref(DnsServer *s) {

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen if (!s)

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen return NULL;

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen assert(s->n_ref > 0);

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen s->n_ref ++;

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen return s;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen}

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom GundersenDnsServer* dns_server_unref(DnsServer *s) {

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen if (!s)

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen return NULL;

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert(s->n_ref > 0);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->n_ref --;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (s->n_ref > 0)

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen return NULL;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen free(s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen return NULL;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen}

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersenvoid dns_server_unlink(DnsServer *s) {

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert(s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert(s->manager);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen /* This removes the specified server from the linked list of

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (!s->linked)

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen return;

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen switch (s->type) {

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen case DNS_SERVER_LINK:

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen assert(s->link);

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen assert(s->link->n_dns_servers > 0);

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen LIST_REMOVE(servers, s->link->dns_servers, s);

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen break;

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen case DNS_SERVER_SYSTEM:

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen assert(s->manager->n_dns_servers > 0);

b95cc756de7a27f7546e42dd9acf6da0669da402Tom Gundersen LIST_REMOVE(servers, s->manager->dns_servers, s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->manager->n_dns_servers--;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen break;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen case DNS_SERVER_FALLBACK:

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert(s->manager->n_dns_servers > 0);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_REMOVE(servers, s->manager->fallback_dns_servers, s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->manager->n_dns_servers--;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen break;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen }

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->linked = false;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (s->link && s->link->current_dns_server == s)

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen link_set_dns_server(s->link, NULL);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (s->manager->current_dns_server == s)

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen manager_set_dns_server(s->manager, NULL);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen dns_server_unref(s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen}

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersenvoid dns_server_move_back_and_unmark(DnsServer *s) {

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen DnsServer *tail;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert(s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (!s->marked)

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen return;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen s->marked = false;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (!s->linked || !s->servers_next)

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen return;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen /* Move us to the end of the list, so that the order is

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen switch (s->type) {

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen case DNS_SERVER_LINK:

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert(s->link);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_FIND_TAIL(servers, s, tail);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_REMOVE(servers, s->link->dns_servers, s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_INSERT_AFTER(servers, s->link->dns_servers, tail, s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen break;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen case DNS_SERVER_SYSTEM:

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_FIND_TAIL(servers, s, tail);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_REMOVE(servers, s->manager->dns_servers, s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_INSERT_AFTER(servers, s->manager->dns_servers, tail, s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen break;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen case DNS_SERVER_FALLBACK:

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_FIND_TAIL(servers, s, tail);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_REMOVE(servers, s->manager->fallback_dns_servers, s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen LIST_INSERT_AFTER(servers, s->manager->fallback_dns_servers, tail, s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen break;

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen default:

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert_not_reached("Unknown server type");

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen }

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen}

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersenvoid dns_server_packet_received(DnsServer *s, DnsServerFeatureLevel features, usec_t rtt, size_t size) {

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen assert(s);

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (features == DNS_SERVER_FEATURE_LEVEL_LARGE) {

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen /* Even if we successfully receive a reply to a

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen

9c5a882b7fc256ddc0b227677fa06546f0e944a8Tom Gundersen if (s->verified_features < DNS_SERVER_FEATURE_LEVEL_LARGE - 1) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->verified_features = DNS_SERVER_FEATURE_LEVEL_LARGE - 1;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert_se(sd_event_now(s->manager->event, clock_boottime_or_monotonic(), &s->verified_usec) >= 0);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen }

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen } else if (s->verified_features < features) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->verified_features = features;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert_se(sd_event_now(s->manager->event, clock_boottime_or_monotonic(), &s->verified_usec) >= 0);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen }

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (s->possible_features == features)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->n_failed_attempts = 0;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen /* Remember the size of the largest UDP packet we received from a server,

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (s->received_udp_packet_max < size)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->received_udp_packet_max = size;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (s->max_rtt < rtt) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->max_rtt = rtt;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->resend_timeout = MIN(MAX(DNS_TIMEOUT_MIN_USEC, s->max_rtt * 2), DNS_TIMEOUT_MAX_USEC);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen }

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersenvoid dns_server_packet_lost(DnsServer *s, DnsServerFeatureLevel features, usec_t usec) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(s);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(s->manager);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (s->possible_features == features)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->n_failed_attempts ++;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (s->resend_timeout > usec)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->resend_timeout = MIN(s->resend_timeout * 2, DNS_TIMEOUT_MAX_USEC);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersenvoid dns_server_packet_failed(DnsServer *s, DnsServerFeatureLevel features) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(s);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(s->manager);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (s->possible_features != features)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->n_failed_attempts = (unsigned) -1;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersenvoid dns_server_packet_rrsig_missing(DnsServer *s) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen _cleanup_free_ char *ip = NULL;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(s);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(s->manager);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen in_addr_to_string(s->family, &s->address, &ip);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen log_warning("DNS server %s does not augment replies with RRSIG records, DNSSEC not available.", strna(ip));

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->rrsig_missing = true;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersenstatic bool dns_server_grace_period_expired(DnsServer *s) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen usec_t ts;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(s);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(s->manager);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (s->verified_usec == 0)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return false;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert_se(sd_event_now(s->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (s->verified_usec + s->features_grace_period_usec > ts)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return false;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->features_grace_period_usec = MIN(s->features_grace_period_usec * 2, DNS_SERVER_FEATURE_GRACE_PERIOD_MAX_USEC);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return true;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom GundersenDnsServerFeatureLevel dns_server_possible_features(DnsServer *s) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(s);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (s->possible_features != DNS_SERVER_FEATURE_LEVEL_BEST &&

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen dns_server_grace_period_expired(s)) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen _cleanup_free_ char *ip = NULL;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->possible_features = DNS_SERVER_FEATURE_LEVEL_BEST;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->n_failed_attempts = 0;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->verified_usec = 0;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->rrsig_missing = false;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen in_addr_to_string(s->family, &s->address, &ip);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen log_info("Grace period over, resuming full feature set for DNS server %s", strna(ip));

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen } else if (s->possible_features <= s->verified_features)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->possible_features = s->verified_features;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen else if (s->n_failed_attempts >= DNS_SERVER_FEATURE_RETRY_ATTEMPTS &&

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->possible_features > DNS_SERVER_FEATURE_LEVEL_WORST) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen _cleanup_free_ char *ip = NULL;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->possible_features --;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->n_failed_attempts = 0;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen s->verified_usec = 0;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen in_addr_to_string(s->family, &s->address, &ip);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen log_warning("Using degraded feature set (%s) for DNS server %s",

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen dns_server_feature_level_to_string(s->possible_features), strna(ip));

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen }

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return s->possible_features;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersenint dns_server_adjust_opt(DnsServer *server, DnsPacket *packet, DnsServerFeatureLevel level) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen size_t packet_size;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen bool edns_do;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen int r;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(server);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(packet);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(packet->protocol == DNS_PROTOCOL_DNS);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen /* Fix the OPT field in the packet to match our current feature level. */

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen r = dns_packet_truncate_opt(packet);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (r < 0)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return r;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (level < DNS_SERVER_FEATURE_LEVEL_EDNS0)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return 0;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen edns_do = level >= DNS_SERVER_FEATURE_LEVEL_DO;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (level >= DNS_SERVER_FEATURE_LEVEL_LARGE)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen packet_size = DNS_PACKET_UNICAST_SIZE_LARGE_MAX;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen else

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen packet_size = server->received_udp_packet_max;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return dns_packet_append_opt(packet, packet_size, edns_do, NULL);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersenstatic void dns_server_hash_func(const void *p, struct siphash *state) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen const DnsServer *s = p;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(s);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen siphash24_compress(&s->family, sizeof(s->family), state);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen siphash24_compress(&s->address, FAMILY_ADDRESS_SIZE(s->family), state);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersenstatic int dns_server_compare_func(const void *a, const void *b) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen const DnsServer *x = a, *y = b;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (x->family < y->family)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return -1;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (x->family > y->family)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return 1;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return memcmp(&x->address, &y->address, FAMILY_ADDRESS_SIZE(x->family));

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersenconst struct hash_ops dns_server_hash_ops = {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen .hash = dns_server_hash_func,

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen .compare = dns_server_compare_func

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen};

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersenvoid dns_server_unlink_all(DnsServer *first) {

846a6b3d89aaf4ee2cece0f10148f675c4796841David Herrmann DnsServer *next;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (!first)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen next = first->servers_next;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen dns_server_unlink(first);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen dns_server_unlink_all(next);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

817d1cd824bedba8feeef24c9724ec8bd160a7b2David Herrmann

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersenvoid dns_server_unlink_marked(DnsServer *first) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen DnsServer *next;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (!first)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen next = first->servers_next;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (first->marked)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen dns_server_unlink(first);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen dns_server_unlink_marked(next);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersenvoid dns_server_mark_all(DnsServer *first) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (!first)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen first->marked = true;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen dns_server_mark_all(first->servers_next);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom GundersenDnsServer *dns_server_find(DnsServer *first, int family, const union in_addr_union *in_addr) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen DnsServer *s;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen LIST_FOREACH(servers, s, first)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (s->family == family && in_addr_equal(family, &s->address, in_addr) > 0)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return s;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return NULL;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom GundersenDnsServer *manager_get_first_dns_server(Manager *m, DnsServerType t) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(m);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen switch (t) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen case DNS_SERVER_SYSTEM:

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return m->dns_servers;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen case DNS_SERVER_FALLBACK:

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return m->fallback_dns_servers;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen default:

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return NULL;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen }

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen}

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom GundersenDnsServer *manager_set_dns_server(Manager *m, DnsServer *s) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen assert(m);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (m->current_dns_server == s)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen return s;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (s) {

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen _cleanup_free_ char *ip = NULL;

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen in_addr_to_string(s->family, &s->address, &ip);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen log_info("Switching to system DNS server %s.", strna(ip));

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen }

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen dns_server_unref(m->current_dns_server);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen m->current_dns_server = dns_server_ref(s);

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen if (m->unicast_scope)

89489ef7d451d61e176764deb608a84e29b1fd38Tom Gundersen dns_cache_flush(&m->unicast_scope->cache);

return s;

}

DnsServer *manager_get_dns_server(Manager *m) {

Link *l;

assert(m);

/* Try to read updates resolv.conf */

manager_read_resolv_conf(m);

/* If no DNS server was chose so far, pick the first one */

if (!m->current_dns_server)

manager_set_dns_server(m, m->dns_servers);

if (!m->current_dns_server) {

bool found = false;

Iterator i;

/* No DNS servers configured, let's see if there are

HASHMAP_FOREACH(l, m->links, i)

if (l->dns_servers) {

found = true;

break;

}

if (!found)

manager_set_dns_server(m, m->fallback_dns_servers);

}

return m->current_dns_server;

}

void manager_next_dns_server(Manager *m) {

assert(m);

/* If there's currently no DNS server set, then the next

if (!m->current_dns_server)

return;

/* Change to the next one, but make sure to follow the linked

if (m->current_dns_server->linked && m->current_dns_server->servers_next) {

manager_set_dns_server(m, m->current_dns_server->servers_next);

return;

}

/* If there was no next one, then start from the beginning of

if (m->current_dns_server->type == DNS_SERVER_FALLBACK)

manager_set_dns_server(m, m->fallback_dns_servers);

else

manager_set_dns_server(m, m->dns_servers);

}

static const char* const dns_server_feature_level_table[_DNS_SERVER_FEATURE_LEVEL_MAX] = {

[DNS_SERVER_FEATURE_LEVEL_TCP] = "TCP",

[DNS_SERVER_FEATURE_LEVEL_UDP] = "UDP",

[DNS_SERVER_FEATURE_LEVEL_EDNS0] = "UDP+EDNS0",

[DNS_SERVER_FEATURE_LEVEL_DO] = "UDP+EDNS0+DO",

[DNS_SERVER_FEATURE_LEVEL_LARGE] = "UDP+EDNS0+DO+LARGE",

};

DEFINE_STRING_TABLE_LOOKUP(dns_server_feature_level, DnsServerFeatureLevel);