-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
/***
This file is part of systemd.
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
-#include "siphash24.h"
+#include <sd-messages.h>
+#include "alloc-util.h"
#include "resolved-dns-server.h"
+#include "resolved-resolv-conf.h"
+#include "siphash24.h"
+#include "string-table.h"
+#include "string-util.h"
/* After how much time to repeat classic DNS requests */
#define DNS_TIMEOUT_MIN_USEC (500 * USEC_PER_MSEC)
#define DNS_TIMEOUT_MAX_USEC (5 * USEC_PER_SEC)
+/* The amount of time to wait before retrying with a full feature set */
+#define DNS_SERVER_FEATURE_GRACE_PERIOD_MAX_USEC (6 * USEC_PER_HOUR)
+#define DNS_SERVER_FEATURE_GRACE_PERIOD_MIN_USEC (5 * USEC_PER_MINUTE)
+
+/* The number of times we will attempt a certain feature set before degrading */
+#define DNS_SERVER_FEATURE_RETRY_ATTEMPTS 3
+
int dns_server_new(
Manager *m,
DnsServer **ret,
int family,
const union in_addr_union *in_addr) {
- DnsServer *s, *tail;
+ DnsServer *s;
assert(m);
assert((type == DNS_SERVER_LINK) == !!l);
assert(in_addr);
+ if (!IN_SET(family, AF_INET, AF_INET6))
+ return -EAFNOSUPPORT;
+
+ if (l) {
+ if (l->n_dns_servers >= LINK_DNS_SERVERS_MAX)
+ return -E2BIG;
+ } else {
+ if (m->n_dns_servers >= MANAGER_DNS_SERVERS_MAX)
+ return -E2BIG;
+ }
+
s = new0(DnsServer, 1);
if (!s)
return -ENOMEM;
s->n_ref = 1;
+ s->manager = m;
+ s->verified_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID;
+ s->possible_feature_level = DNS_SERVER_FEATURE_LEVEL_BEST;
+ s->features_grace_period_usec = DNS_SERVER_FEATURE_GRACE_PERIOD_MIN_USEC;
+ s->received_udp_packet_max = DNS_PACKET_UNICAST_SIZE_MAX;
s->type = type;
s->family = family;
s->address = *in_addr;
s->resend_timeout = DNS_TIMEOUT_MIN_USEC;
- if (type == DNS_SERVER_LINK) {
- LIST_FIND_TAIL(servers, l->dns_servers, tail);
- LIST_INSERT_AFTER(servers, l->dns_servers, tail, s);
+ switch (type) {
+
+ case DNS_SERVER_LINK:
s->link = l;
- } else if (type == DNS_SERVER_SYSTEM) {
- LIST_FIND_TAIL(servers, m->dns_servers, tail);
- LIST_INSERT_AFTER(servers, m->dns_servers, tail, s);
- } else if (type == DNS_SERVER_FALLBACK) {
- LIST_FIND_TAIL(servers, m->fallback_dns_servers, tail);
- LIST_INSERT_AFTER(servers, m->fallback_dns_servers, tail, s);
- } else
+ LIST_APPEND(servers, l->dns_servers, s);
+ l->n_dns_servers++;
+ break;
+
+ case DNS_SERVER_SYSTEM:
+ LIST_APPEND(servers, m->dns_servers, s);
+ m->n_dns_servers++;
+ break;
+
+ case DNS_SERVER_FALLBACK:
+ LIST_APPEND(servers, m->fallback_dns_servers, s);
+ m->n_dns_servers++;
+ break;
+
+ default:
assert_not_reached("Unknown server type");
+ }
- s->manager = m;
+ s->linked = true;
/* A new DNS server that isn't fallback is added and the one
* we used so far was a fallback one? Then let's try to pick
return NULL;
assert(s->n_ref > 0);
-
s->n_ref ++;
return s;
}
-static DnsServer* dns_server_free(DnsServer *s) {
+DnsServer* dns_server_unref(DnsServer *s) {
if (!s)
return NULL;
+ assert(s->n_ref > 0);
+ s->n_ref --;
+
+ if (s->n_ref > 0)
+ return NULL;
+
+ free(s->server_string);
+ free(s);
+ return NULL;
+}
+
+void dns_server_unlink(DnsServer *s) {
+ assert(s);
+ assert(s->manager);
+
+ /* This removes the specified server from the linked list of
+ * servers, but any server might still stay around if it has
+ * refs, for example from an ongoing transaction. */
+
+ if (!s->linked)
+ return;
+
+ switch (s->type) {
+
+ case DNS_SERVER_LINK:
+ assert(s->link);
+ assert(s->link->n_dns_servers > 0);
+ LIST_REMOVE(servers, s->link->dns_servers, s);
+ break;
+
+ case DNS_SERVER_SYSTEM:
+ assert(s->manager->n_dns_servers > 0);
+ LIST_REMOVE(servers, s->manager->dns_servers, s);
+ s->manager->n_dns_servers--;
+ break;
+
+ case DNS_SERVER_FALLBACK:
+ assert(s->manager->n_dns_servers > 0);
+ LIST_REMOVE(servers, s->manager->fallback_dns_servers, s);
+ s->manager->n_dns_servers--;
+ break;
+ }
+
+ s->linked = false;
+
if (s->link && s->link->current_dns_server == s)
link_set_dns_server(s->link, NULL);
- if (s->manager && s->manager->current_dns_server == s)
+ if (s->manager->current_dns_server == s)
manager_set_dns_server(s->manager, NULL);
- free(s);
+ dns_server_unref(s);
+}
- return NULL;
+void dns_server_move_back_and_unmark(DnsServer *s) {
+ DnsServer *tail;
+
+ assert(s);
+
+ if (!s->marked)
+ return;
+
+ s->marked = false;
+
+ if (!s->linked || !s->servers_next)
+ return;
+
+ /* Move us to the end of the list, so that the order is
+ * strictly kept, if we are not at the end anyway. */
+
+ switch (s->type) {
+
+ case DNS_SERVER_LINK:
+ assert(s->link);
+ LIST_FIND_TAIL(servers, s, tail);
+ LIST_REMOVE(servers, s->link->dns_servers, s);
+ LIST_INSERT_AFTER(servers, s->link->dns_servers, tail, s);
+ break;
+
+ case DNS_SERVER_SYSTEM:
+ LIST_FIND_TAIL(servers, s, tail);
+ LIST_REMOVE(servers, s->manager->dns_servers, s);
+ LIST_INSERT_AFTER(servers, s->manager->dns_servers, tail, s);
+ break;
+
+ case DNS_SERVER_FALLBACK:
+ LIST_FIND_TAIL(servers, s, tail);
+ LIST_REMOVE(servers, s->manager->fallback_dns_servers, s);
+ LIST_INSERT_AFTER(servers, s->manager->fallback_dns_servers, tail, s);
+ break;
+
+ default:
+ assert_not_reached("Unknown server type");
+ }
}
-DnsServer* dns_server_unref(DnsServer *s) {
- if (!s)
- return NULL;
+static void dns_server_verified(DnsServer *s, DnsServerFeatureLevel level) {
+ assert(s);
- assert(s->n_ref > 0);
+ if (s->verified_feature_level > level)
+ return;
- if (s->n_ref == 1)
- dns_server_free(s);
- else
- s->n_ref --;
+ if (s->verified_feature_level != level) {
+ log_debug("Verified we get a response at feature level %s from DNS server %s.",
+ dns_server_feature_level_to_string(level),
+ dns_server_string(s));
+ s->verified_feature_level = level;
+ }
- return NULL;
+ assert_se(sd_event_now(s->manager->event, clock_boottime_or_monotonic(), &s->verified_usec) >= 0);
}
-void dns_server_packet_received(DnsServer *s, usec_t rtt) {
+void dns_server_packet_received(DnsServer *s, int protocol, DnsServerFeatureLevel level, usec_t rtt, size_t size) {
assert(s);
- if (rtt > s->max_rtt) {
+ if (protocol == IPPROTO_UDP) {
+ if (s->possible_feature_level == level)
+ s->n_failed_udp = 0;
+
+ /* If the RRSIG data is missing, then we can only validate EDNS0 at max */
+ if (s->packet_rrsig_missing && level >= DNS_SERVER_FEATURE_LEVEL_DO)
+ level = DNS_SERVER_FEATURE_LEVEL_DO - 1;
+
+ /* If the OPT RR got lost, then we can only validate UDP at max */
+ if (s->packet_bad_opt && level >= DNS_SERVER_FEATURE_LEVEL_EDNS0)
+ level = DNS_SERVER_FEATURE_LEVEL_EDNS0 - 1;
+
+ /* Even if we successfully receive a reply to a request announcing support for large packets,
+ that does not mean we can necessarily receive large packets. */
+ if (level == DNS_SERVER_FEATURE_LEVEL_LARGE)
+ level = DNS_SERVER_FEATURE_LEVEL_LARGE - 1;
+
+ } else if (protocol == IPPROTO_TCP) {
+
+ if (s->possible_feature_level == level)
+ s->n_failed_tcp = 0;
+
+ /* Successful TCP connections are only useful to verify the TCP feature level. */
+ level = DNS_SERVER_FEATURE_LEVEL_TCP;
+ }
+
+ dns_server_verified(s, level);
+
+ /* Remember the size of the largest UDP packet we received from a server,
+ we know that we can always announce support for packets with at least
+ this size. */
+ if (protocol == IPPROTO_UDP && s->received_udp_packet_max < size)
+ s->received_udp_packet_max = size;
+
+ if (s->max_rtt < rtt) {
s->max_rtt = rtt;
- s->resend_timeout = MIN(MAX(DNS_TIMEOUT_MIN_USEC, s->max_rtt * 2),
- DNS_TIMEOUT_MAX_USEC);
+ s->resend_timeout = CLAMP(s->max_rtt * 2, DNS_TIMEOUT_MIN_USEC, DNS_TIMEOUT_MAX_USEC);
}
}
-void dns_server_packet_lost(DnsServer *s, usec_t usec) {
+void dns_server_packet_lost(DnsServer *s, int protocol, DnsServerFeatureLevel level, usec_t usec) {
+ assert(s);
+ assert(s->manager);
+
+ if (s->possible_feature_level == level) {
+ if (protocol == IPPROTO_UDP)
+ s->n_failed_udp ++;
+ else if (protocol == IPPROTO_TCP)
+ s->n_failed_tcp ++;
+ }
+
+ if (s->resend_timeout > usec)
+ return;
+
+ s->resend_timeout = MIN(s->resend_timeout * 2, DNS_TIMEOUT_MAX_USEC);
+}
+
+void dns_server_packet_failed(DnsServer *s, DnsServerFeatureLevel level) {
+ assert(s);
+
+ /* Invoked whenever we get a FORMERR, SERVFAIL or NOTIMP rcode from a server. */
+
+ if (s->possible_feature_level != level)
+ return;
+
+ s->packet_failed = true;
+}
+
+void dns_server_packet_truncated(DnsServer *s, DnsServerFeatureLevel level) {
assert(s);
- if (s->resend_timeout <= usec)
- s->resend_timeout = MIN(s->resend_timeout * 2, DNS_TIMEOUT_MAX_USEC);
+ /* Invoked whenever we get a packet with TC bit set. */
+
+ if (s->possible_feature_level != level)
+ return;
+
+ s->packet_truncated = true;
+}
+
+void dns_server_packet_rrsig_missing(DnsServer *s, DnsServerFeatureLevel level) {
+ assert(s);
+
+ if (level < DNS_SERVER_FEATURE_LEVEL_DO)
+ return;
+
+ /* If the RRSIG RRs are missing, we have to downgrade what we previously verified */
+ if (s->verified_feature_level >= DNS_SERVER_FEATURE_LEVEL_DO)
+ s->verified_feature_level = DNS_SERVER_FEATURE_LEVEL_DO-1;
+
+ s->packet_rrsig_missing = true;
+}
+
+void dns_server_packet_bad_opt(DnsServer *s, DnsServerFeatureLevel level) {
+ assert(s);
+
+ if (level < DNS_SERVER_FEATURE_LEVEL_EDNS0)
+ return;
+
+ /* If the OPT RR got lost, we have to downgrade what we previously verified */
+ if (s->verified_feature_level >= DNS_SERVER_FEATURE_LEVEL_EDNS0)
+ s->verified_feature_level = DNS_SERVER_FEATURE_LEVEL_EDNS0-1;
+
+ s->packet_bad_opt = true;
+}
+
+static bool dns_server_grace_period_expired(DnsServer *s) {
+ usec_t ts;
+
+ assert(s);
+ assert(s->manager);
+
+ if (s->verified_usec == 0)
+ return false;
+
+ assert_se(sd_event_now(s->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
+
+ if (s->verified_usec + s->features_grace_period_usec > ts)
+ return false;
+
+ s->features_grace_period_usec = MIN(s->features_grace_period_usec * 2, DNS_SERVER_FEATURE_GRACE_PERIOD_MAX_USEC);
+
+ return true;
+}
+
+static void dns_server_reset_counters(DnsServer *s) {
+ assert(s);
+
+ s->n_failed_udp = 0;
+ s->n_failed_tcp = 0;
+ s->packet_failed = false;
+ s->packet_truncated = false;
+ s->verified_usec = 0;
+
+ /* Note that we do not reset s->packet_bad_opt and s->packet_rrsig_missing here. We reset them only when the
+ * grace period ends, but not when lowering the possible feature level, as a lower level feature level should
+ * not make RRSIGs appear or OPT appear, but rather make them disappear. If the reappear anyway, then that's
+ * indication for a differently broken OPT/RRSIG implementation, and we really don't want to support that
+ * either.
+ *
+ * This is particularly important to deal with certain Belkin routers which break OPT for certain lookups (A),
+ * but pass traffic through for others (AAAA). If we detect the broken behaviour on one lookup we should not
+ * reenable it for another, because we cannot validate things anyway, given that the RRSIG/OPT data will be
+ * incomplete. */
+}
+
+DnsServerFeatureLevel dns_server_possible_feature_level(DnsServer *s) {
+ assert(s);
+
+ if (s->possible_feature_level != DNS_SERVER_FEATURE_LEVEL_BEST &&
+ dns_server_grace_period_expired(s)) {
+
+ s->possible_feature_level = DNS_SERVER_FEATURE_LEVEL_BEST;
+
+ dns_server_reset_counters(s);
+
+ s->packet_bad_opt = false;
+ s->packet_rrsig_missing = false;
+
+ log_info("Grace period over, resuming full feature set (%s) for DNS server %s.",
+ dns_server_feature_level_to_string(s->possible_feature_level),
+ dns_server_string(s));
+
+ } else if (s->possible_feature_level <= s->verified_feature_level)
+ s->possible_feature_level = s->verified_feature_level;
+ else {
+ DnsServerFeatureLevel p = s->possible_feature_level;
+
+ if (s->n_failed_tcp >= DNS_SERVER_FEATURE_RETRY_ATTEMPTS &&
+ s->possible_feature_level == DNS_SERVER_FEATURE_LEVEL_TCP) {
+
+ /* We are at the TCP (lowest) level, and we tried a couple of TCP connections, and it didn't
+ * work. Upgrade back to UDP again. */
+ log_debug("Reached maximum number of failed TCP connection attempts, trying UDP again...");
+ s->possible_feature_level = DNS_SERVER_FEATURE_LEVEL_UDP;
+
+ } else if (s->packet_bad_opt &&
+ s->possible_feature_level >= DNS_SERVER_FEATURE_LEVEL_EDNS0) {
+
+ /* A reply to one of our EDNS0 queries didn't carry a valid OPT RR, then downgrade to below
+ * EDNS0 levels. After all, some records generate different responses with and without OPT RR
+ * in the request. Example:
+ * https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */
+
+ log_debug("Server doesn't support EDNS(0) properly, downgrading feature level...");
+ s->possible_feature_level = DNS_SERVER_FEATURE_LEVEL_UDP;
+
+ } else if (s->packet_rrsig_missing &&
+ s->possible_feature_level >= DNS_SERVER_FEATURE_LEVEL_DO) {
+
+ /* RRSIG data was missing on a EDNS0 packet with DO bit set. This means the server doesn't
+ * augment responses with DNSSEC RRs. If so, let's better not ask the server for it anymore,
+ * after all some servers generate different replies depending if an OPT RR is in the query or
+ * not. */
+
+ log_debug("Detected server responses lack RRSIG records, downgrading feature level...");
+ s->possible_feature_level = DNS_SERVER_FEATURE_LEVEL_EDNS0;
+
+ } else if (s->n_failed_udp >= DNS_SERVER_FEATURE_RETRY_ATTEMPTS &&
+ s->possible_feature_level >= DNS_SERVER_FEATURE_LEVEL_UDP) {
+
+ /* We lost too many UDP packets in a row, and are on a feature level of UDP or higher. If the
+ * packets are lost, maybe the server cannot parse them, hence downgrading sounds like a good
+ * idea. We might downgrade all the way down to TCP this way. */
+
+ log_debug("Lost too many UDP packets, downgrading feature level...");
+ s->possible_feature_level--;
+
+ } else if (s->packet_failed &&
+ s->possible_feature_level > DNS_SERVER_FEATURE_LEVEL_UDP) {
+
+ /* We got a failure packet, and are at a feature level above UDP. Note that in this case we
+ * downgrade no further than UDP, under the assumption that a failure packet indicates an
+ * incompatible packet contents, but not a problem with the transport. */
+
+ log_debug("Got server failure, downgrading feature level...");
+ s->possible_feature_level--;
+
+ } else if (s->n_failed_tcp >= DNS_SERVER_FEATURE_RETRY_ATTEMPTS &&
+ s->packet_truncated &&
+ s->possible_feature_level > DNS_SERVER_FEATURE_LEVEL_UDP) {
+
+ /* We got too many TCP connection failures in a row, we had at least one truncated packet, and
+ * are on a feature level above UDP. By downgrading things and getting rid of DNSSEC or EDNS0
+ * data we hope to make the packet smaller, so that it still works via UDP given that TCP
+ * appears not to be a fallback. Note that if we are already at the lowest UDP level, we don't
+ * go further down, since that's TCP, and TCP failed too often after all. */
+
+ log_debug("Got too many failed TCP connection failures and truncated UDP packets, downgrading feature level...");
+ s->possible_feature_level--;
+ }
+
+ if (p != s->possible_feature_level) {
+
+ /* We changed the feature level, reset the counting */
+ dns_server_reset_counters(s);
+
+ log_warning("Using degraded feature set (%s) for DNS server %s.",
+ dns_server_feature_level_to_string(s->possible_feature_level),
+ dns_server_string(s));
+ }
+ }
+
+ return s->possible_feature_level;
+}
+
+int dns_server_adjust_opt(DnsServer *server, DnsPacket *packet, DnsServerFeatureLevel level) {
+ size_t packet_size;
+ bool edns_do;
+ int r;
+
+ assert(server);
+ assert(packet);
+ assert(packet->protocol == DNS_PROTOCOL_DNS);
+
+ /* Fix the OPT field in the packet to match our current feature level. */
+
+ r = dns_packet_truncate_opt(packet);
+ if (r < 0)
+ return r;
+
+ if (level < DNS_SERVER_FEATURE_LEVEL_EDNS0)
+ return 0;
+
+ edns_do = level >= DNS_SERVER_FEATURE_LEVEL_DO;
+
+ if (level >= DNS_SERVER_FEATURE_LEVEL_LARGE)
+ packet_size = DNS_PACKET_UNICAST_SIZE_LARGE_MAX;
+ else
+ packet_size = server->received_udp_packet_max;
+
+ return dns_packet_append_opt(packet, packet_size, edns_do, NULL);
+}
+
+const char *dns_server_string(DnsServer *server) {
+ assert(server);
+
+ if (!server->server_string)
+ (void) in_addr_to_string(server->family, &server->address, &server->server_string);
+
+ return strna(server->server_string);
+}
+
+bool dns_server_dnssec_supported(DnsServer *server) {
+ assert(server);
+
+ /* Returns whether the server supports DNSSEC according to what we know about it */
+
+ if (server->possible_feature_level < DNS_SERVER_FEATURE_LEVEL_DO)
+ return false;
+
+ if (server->packet_bad_opt)
+ return false;
+
+ if (server->packet_rrsig_missing)
+ return false;
+
+ /* DNSSEC servers need to support TCP properly (see RFC5966), if they don't, we assume DNSSEC is borked too */
+ if (server->n_failed_tcp >= DNS_SERVER_FEATURE_RETRY_ATTEMPTS)
+ return false;
+
+ return true;
+}
+
+void dns_server_warn_downgrade(DnsServer *server) {
+ assert(server);
+
+ if (server->warned_downgrade)
+ return;
+
+ log_struct(LOG_NOTICE,
+ LOG_MESSAGE_ID(SD_MESSAGE_DNSSEC_DOWNGRADE),
+ LOG_MESSAGE("Server %s does not support DNSSEC, downgrading to non-DNSSEC mode.", dns_server_string(server)),
+ "DNS_SERVER=%s", dns_server_string(server),
+ "DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(server->possible_feature_level),
+ NULL);
+
+ server->warned_downgrade = true;
}
static void dns_server_hash_func(const void *p, struct siphash *state) {
.hash = dns_server_hash_func,
.compare = dns_server_compare_func
};
+
+void dns_server_unlink_all(DnsServer *first) {
+ DnsServer *next;
+
+ if (!first)
+ return;
+
+ next = first->servers_next;
+ dns_server_unlink(first);
+
+ dns_server_unlink_all(next);
+}
+
+void dns_server_unlink_marked(DnsServer *first) {
+ DnsServer *next;
+
+ if (!first)
+ return;
+
+ next = first->servers_next;
+
+ if (first->marked)
+ dns_server_unlink(first);
+
+ dns_server_unlink_marked(next);
+}
+
+void dns_server_mark_all(DnsServer *first) {
+ if (!first)
+ return;
+
+ first->marked = true;
+ dns_server_mark_all(first->servers_next);
+}
+
+DnsServer *dns_server_find(DnsServer *first, int family, const union in_addr_union *in_addr) {
+ DnsServer *s;
+
+ LIST_FOREACH(servers, s, first)
+ if (s->family == family && in_addr_equal(family, &s->address, in_addr) > 0)
+ return s;
+
+ return NULL;
+}
+
+DnsServer *manager_get_first_dns_server(Manager *m, DnsServerType t) {
+ assert(m);
+
+ switch (t) {
+
+ case DNS_SERVER_SYSTEM:
+ return m->dns_servers;
+
+ case DNS_SERVER_FALLBACK:
+ return m->fallback_dns_servers;
+
+ default:
+ return NULL;
+ }
+}
+
+DnsServer *manager_set_dns_server(Manager *m, DnsServer *s) {
+ assert(m);
+
+ if (m->current_dns_server == s)
+ return s;
+
+ if (s)
+ log_info("Switching to %s DNS server %s.",
+ dns_server_type_to_string(s->type),
+ dns_server_string(s));
+
+ dns_server_unref(m->current_dns_server);
+ m->current_dns_server = dns_server_ref(s);
+
+ if (m->unicast_scope)
+ 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 chosen 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
+ * any on any links. If not, we use the fallback
+ * servers */
+
+ 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
+ * manager_get_dns_server() will find one */
+ if (!m->current_dns_server)
+ return;
+
+ /* Change to the next one, but make sure to follow the linked
+ * list only if the server is still 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
+ * the list */
+ 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_type_table[_DNS_SERVER_TYPE_MAX] = {
+ [DNS_SERVER_SYSTEM] = "system",
+ [DNS_SERVER_FALLBACK] = "fallback",
+ [DNS_SERVER_LINK] = "link",
+};
+DEFINE_STRING_TABLE_LOOKUP(dns_server_type, DnsServerType);
+
+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);
projects / thirdparty / systemd.git / blobdiff