Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1860 insertions, 0 deletions

diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
new file mode 100644
index 0000000..b52619e
--- /dev/null
+++ b/src/resolve/resolved-manager.c
@@ -0,0 +1,1860 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <poll.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "af-list.h"
+#include "alloc-util.h"
+#include "bus-polkit.h"
+#include "dirent-util.h"
+#include "dns-domain.h"
+#include "event-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "hostname-util.h"
+#include "idn-util.h"
+#include "io-util.h"
+#include "iovec-util.h"
+#include "memstream-util.h"
+#include "missing_network.h"
+#include "missing_socket.h"
+#include "netlink-util.h"
+#include "ordered-set.h"
+#include "parse-util.h"
+#include "random-util.h"
+#include "resolved-bus.h"
+#include "resolved-conf.h"
+#include "resolved-dns-stub.h"
+#include "resolved-dnssd.h"
+#include "resolved-etc-hosts.h"
+#include "resolved-llmnr.h"
+#include "resolved-manager.h"
+#include "resolved-mdns.h"
+#include "resolved-resolv-conf.h"
+#include "resolved-util.h"
+#include "resolved-varlink.h"
+#include "socket-util.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "utf8.h"
+
+#define SEND_TIMEOUT_USEC (200 * USEC_PER_MSEC)
+
+static int manager_process_link(sd_netlink *rtnl, sd_netlink_message *mm, void *userdata) {
+        Manager *m = ASSERT_PTR(userdata);
+        uint16_t type;
+        Link *l;
+        int ifindex, r;
+
+        assert(rtnl);
+        assert(mm);
+
+        r = sd_netlink_message_get_type(mm, &type);
+        if (r < 0)
+                goto fail;
+
+        r = sd_rtnl_message_link_get_ifindex(mm, &ifindex);
+        if (r < 0)
+                goto fail;
+
+        l = hashmap_get(m->links, INT_TO_PTR(ifindex));
+
+        switch (type) {
+
+        case RTM_NEWLINK:{
+                bool is_new = !l;
+
+                if (!l) {
+                        r = link_new(m, &l, ifindex);
+                        if (r < 0)
+                                goto fail;
+                }
+
+                r = link_process_rtnl(l, mm);
+                if (r < 0)
+                        goto fail;
+
+                r = link_update(l);
+                if (r < 0)
+                        goto fail;
+
+                if (is_new)
+                        log_debug("Found new link %i/%s", ifindex, l->ifname);
+
+                break;
+        }
+
+        case RTM_DELLINK:
+                if (l) {
+                        log_debug("Removing link %i/%s", l->ifindex, l->ifname);
+                        link_remove_user(l);
+                        link_free(l);
+                }
+
+                break;
+        }
+
+        return 0;
+
+fail:
+        log_warning_errno(r, "Failed to process RTNL link message: %m");
+        return 0;
+}
+
+static int manager_process_address(sd_netlink *rtnl, sd_netlink_message *mm, void *userdata) {
+        Manager *m = ASSERT_PTR(userdata);
+        union in_addr_union address, broadcast = {};
+        uint16_t type;
+        int r, ifindex, family;
+        LinkAddress *a;
+        Link *l;
+
+        assert(rtnl);
+        assert(mm);
+
+        r = sd_netlink_message_get_type(mm, &type);
+        if (r < 0)
+                goto fail;
+
+        r = sd_rtnl_message_addr_get_ifindex(mm, &ifindex);
+        if (r < 0)
+                goto fail;
+
+        l = hashmap_get(m->links, INT_TO_PTR(ifindex));
+        if (!l)
+                return 0;
+
+        r = sd_rtnl_message_addr_get_family(mm, &family);
+        if (r < 0)
+                goto fail;
+
+        switch (family) {
+
+        case AF_INET:
+                sd_netlink_message_read_in_addr(mm, IFA_BROADCAST, &broadcast.in);
+                r = sd_netlink_message_read_in_addr(mm, IFA_LOCAL, &address.in);
+                if (r < 0) {
+                        r = sd_netlink_message_read_in_addr(mm, IFA_ADDRESS, &address.in);
+                        if (r < 0)
+                                goto fail;
+                }
+
+                break;
+
+        case AF_INET6:
+                r = sd_netlink_message_read_in6_addr(mm, IFA_LOCAL, &address.in6);
+                if (r < 0) {
+                        r = sd_netlink_message_read_in6_addr(mm, IFA_ADDRESS, &address.in6);
+                        if (r < 0)
+                                goto fail;
+                }
+
+                break;
+
+        default:
+                return 0;
+        }
+
+        a = link_find_address(l, family, &address);
+
+        switch (type) {
+
+        case RTM_NEWADDR:
+
+                if (!a) {
+                        r = link_address_new(l, &a, family, &address, &broadcast);
+                        if (r < 0)
+                                return r;
+                }
+
+                r = link_address_update_rtnl(a, mm);
+                if (r < 0)
+                        return r;
+
+                break;
+
+        case RTM_DELADDR:
+                link_address_free(a);
+                break;
+        }
+
+        return 0;
+
+fail:
+        log_warning_errno(r, "Failed to process RTNL address message: %m");
+        return 0;
+}
+
+static int manager_rtnl_listen(Manager *m) {
+        _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *req = NULL, *reply = NULL;
+        int r;
+
+        assert(m);
+
+        /* First, subscribe to interfaces coming and going */
+        r = sd_netlink_open(&m->rtnl);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_attach_event(m->rtnl, m->event, SD_EVENT_PRIORITY_IMPORTANT);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_add_match(m->rtnl, NULL, RTM_NEWLINK, manager_process_link, NULL, m, "resolve-NEWLINK");
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_add_match(m->rtnl, NULL, RTM_DELLINK, manager_process_link, NULL, m, "resolve-DELLINK");
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_add_match(m->rtnl, NULL, RTM_NEWADDR, manager_process_address, NULL, m, "resolve-NEWADDR");
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_add_match(m->rtnl, NULL, RTM_DELADDR, manager_process_address, NULL, m, "resolve-DELADDR");
+        if (r < 0)
+                return r;
+
+        /* Then, enumerate all links */
+        r = sd_rtnl_message_new_link(m->rtnl, &req, RTM_GETLINK, 0);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_set_request_dump(req, true);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_call(m->rtnl, req, 0, &reply);
+        if (r < 0)
+                return r;
+
+        for (sd_netlink_message *i = reply; i; i = sd_netlink_message_next(i)) {
+                r = manager_process_link(m->rtnl, i, m);
+                if (r < 0)
+                        return r;
+        }
+
+        req = sd_netlink_message_unref(req);
+        reply = sd_netlink_message_unref(reply);
+
+        /* Finally, enumerate all addresses, too */
+        r = sd_rtnl_message_new_addr(m->rtnl, &req, RTM_GETADDR, 0, AF_UNSPEC);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_set_request_dump(req, true);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_call(m->rtnl, req, 0, &reply);
+        if (r < 0)
+                return r;
+
+        for (sd_netlink_message *i = reply; i; i = sd_netlink_message_next(i)) {
+                r = manager_process_address(m->rtnl, i, m);
+                if (r < 0)
+                        return r;
+        }
+
+        return r;
+}
+
+static int on_network_event(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+        Manager *m = ASSERT_PTR(userdata);
+        Link *l;
+        int r;
+
+        sd_network_monitor_flush(m->network_monitor);
+
+        HASHMAP_FOREACH(l, m->links) {
+                r = link_update(l);
+                if (r < 0)
+                        log_warning_errno(r, "Failed to update monitor information for %i: %m", l->ifindex);
+        }
+
+        (void) manager_write_resolv_conf(m);
+        (void) manager_send_changed(m, "DNS");
+
+        return 0;
+}
+
+static int manager_network_monitor_listen(Manager *m) {
+        int r, fd, events;
+
+        assert(m);
+
+        r = sd_network_monitor_new(&m->network_monitor, NULL);
+        if (r < 0)
+                return r;
+
+        fd = sd_network_monitor_get_fd(m->network_monitor);
+        if (fd < 0)
+                return fd;
+
+        events = sd_network_monitor_get_events(m->network_monitor);
+        if (events < 0)
+                return events;
+
+        r = sd_event_add_io(m->event, &m->network_event_source, fd, events, &on_network_event, m);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_priority(m->network_event_source, SD_EVENT_PRIORITY_IMPORTANT+5);
+        if (r < 0)
+                return r;
+
+        (void) sd_event_source_set_description(m->network_event_source, "network-monitor");
+
+        return 0;
+}
+
+static int manager_clock_change_listen(Manager *m);
+
+static int on_clock_change(sd_event_source *source, int fd, uint32_t revents, void *userdata) {
+        Manager *m = ASSERT_PTR(userdata);
+
+        /* The clock has changed, let's flush all caches. Why that? That's because DNSSEC validation takes
+         * the system clock into consideration, and if the clock changes the old validations might have been
+         * wrong. Let's redo all validation with the new, correct time.
+         *
+         * (Also, this is triggered after system suspend, which is also a good reason to drop caches, since
+         * we might be connected to a different network now without this being visible in a dropped link
+         * carrier or so.) */
+
+        log_info("Clock change detected. Flushing caches.");
+        manager_flush_caches(m, LOG_DEBUG /* downgrade the functions own log message, since we already logged here at LOG_INFO level */);
+
+        /* The clock change timerfd is unusable after it triggered once, create a new one. */
+        return manager_clock_change_listen(m);
+}
+
+static int manager_clock_change_listen(Manager *m) {
+        int r;
+
+        assert(m);
+
+        m->clock_change_event_source = sd_event_source_disable_unref(m->clock_change_event_source);
+
+        r = event_add_time_change(m->event, &m->clock_change_event_source, on_clock_change, m);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create clock change event source: %m");
+
+        return 0;
+}
+
+static int determine_hostnames(char **full_hostname, char **llmnr_hostname, char **mdns_hostname) {
+        _cleanup_free_ char *h = NULL, *n = NULL;
+        int r;
+
+        assert(full_hostname);
+        assert(llmnr_hostname);
+        assert(mdns_hostname);
+
+        r = resolve_system_hostname(&h, &n);
+        if (r < 0)
+                return r;
+
+        r = dns_name_concat(n, "local", 0, mdns_hostname);
+        if (r < 0)
+                return log_error_errno(r, "Failed to determine mDNS hostname: %m");
+
+        *llmnr_hostname = TAKE_PTR(n);
+        *full_hostname = TAKE_PTR(h);
+
+        return 0;
+}
+
+static char* fallback_hostname(void) {
+
+        /* Determine the fall back hostname. For exposing this system to the outside world, we cannot have it
+         * to be "localhost" even if that's the default hostname. In this case, let's revert to "linux"
+         * instead. */
+
+        _cleanup_free_ char *n = get_default_hostname();
+        if (!n)
+                return NULL;
+
+        if (is_localhost(n))
+                return strdup("linux");
+
+        return TAKE_PTR(n);
+}
+
+static int make_fallback_hostnames(char **full_hostname, char **llmnr_hostname, char **mdns_hostname) {
+        _cleanup_free_ char *h = NULL, *n = NULL, *m = NULL;
+        char label[DNS_LABEL_MAX];
+        const char *p;
+        int r;
+
+        assert(full_hostname);
+        assert(llmnr_hostname);
+        assert(mdns_hostname);
+
+        p = h = fallback_hostname();
+        if (!h)
+                return log_oom();
+
+        r = dns_label_unescape(&p, label, sizeof label, 0);
+        if (r < 0)
+                return log_error_errno(r, "Failed to unescape fallback hostname: %m");
+
+        assert(r > 0); /* The fallback hostname must have at least one label */
+
+        r = dns_label_escape_new(label, r, &n);
+        if (r < 0)
+                return log_error_errno(r, "Failed to escape fallback hostname: %m");
+
+        r = dns_name_concat(n, "local", 0, &m);
+        if (r < 0)
+                return log_error_errno(r, "Failed to concatenate mDNS hostname: %m");
+
+        *llmnr_hostname = TAKE_PTR(n);
+        *mdns_hostname = TAKE_PTR(m);
+        *full_hostname = TAKE_PTR(h);
+
+        return 0;
+}
+
+static int on_hostname_change(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
+        _cleanup_free_ char *full_hostname = NULL, *llmnr_hostname = NULL, *mdns_hostname = NULL;
+        Manager *m = ASSERT_PTR(userdata);
+        bool llmnr_hostname_changed;
+        int r;
+
+        r = determine_hostnames(&full_hostname, &llmnr_hostname, &mdns_hostname);
+        if (r < 0) {
+                log_warning_errno(r, "Failed to determine the local hostname and LLMNR/mDNS names, ignoring: %m");
+                return 0; /* ignore invalid hostnames */
+        }
+
+        llmnr_hostname_changed = !streq(llmnr_hostname, m->llmnr_hostname);
+        if (streq(full_hostname, m->full_hostname) &&
+            !llmnr_hostname_changed &&
+            streq(mdns_hostname, m->mdns_hostname))
+                return 0;
+
+        log_info("System hostname changed to '%s'.", full_hostname);
+
+        free_and_replace(m->full_hostname, full_hostname);
+        free_and_replace(m->llmnr_hostname, llmnr_hostname);
+        free_and_replace(m->mdns_hostname, mdns_hostname);
+
+        manager_refresh_rrs(m);
+        (void) manager_send_changed(m, "LLMNRHostname");
+
+        return 0;
+}
+
+static int manager_watch_hostname(Manager *m) {
+        int r;
+
+        assert(m);
+
+        m->hostname_fd = open("/proc/sys/kernel/hostname",
+                              O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
+        if (m->hostname_fd < 0) {
+                log_warning_errno(errno, "Failed to watch hostname: %m");
+                return 0;
+        }
+
+        r = sd_event_add_io(m->event, &m->hostname_event_source, m->hostname_fd, 0, on_hostname_change, m);
+        if (r < 0) {
+                if (r == -EPERM)
+                        /* kernels prior to 3.2 don't support polling this file. Ignore the failure. */
+                        m->hostname_fd = safe_close(m->hostname_fd);
+                else
+                        return log_error_errno(r, "Failed to add hostname event source: %m");
+        }
+
+        (void) sd_event_source_set_description(m->hostname_event_source, "hostname");
+
+        r = determine_hostnames(&m->full_hostname, &m->llmnr_hostname, &m->mdns_hostname);
+        if (r < 0) {
+                _cleanup_free_ char *d = NULL;
+
+                d = fallback_hostname();
+                if (!d)
+                        return log_oom();
+
+                log_info("Defaulting to hostname '%s'.", d);
+
+                r = make_fallback_hostnames(&m->full_hostname, &m->llmnr_hostname, &m->mdns_hostname);
+                if (r < 0)
+                        return r;
+        } else
+                log_info("Using system hostname '%s'.", m->full_hostname);
+
+        return 0;
+}
+
+static int manager_sigusr1(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
+        _cleanup_(memstream_done) MemStream ms = {};
+        Manager *m = ASSERT_PTR(userdata);
+        Link *l;
+        FILE *f;
+
+        assert(s);
+        assert(si);
+
+        f = memstream_init(&ms);
+        if (!f)
+                return log_oom();
+
+        LIST_FOREACH(scopes, scope, m->dns_scopes)
+                dns_scope_dump(scope, f);
+
+        LIST_FOREACH(servers, server, m->dns_servers)
+                dns_server_dump(server, f);
+        LIST_FOREACH(servers, server, m->fallback_dns_servers)
+                dns_server_dump(server, f);
+        HASHMAP_FOREACH(l, m->links)
+                LIST_FOREACH(servers, server, l->dns_servers)
+                        dns_server_dump(server, f);
+
+        return memstream_dump(LOG_INFO, &ms);
+}
+
+static int manager_sigusr2(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
+        Manager *m = ASSERT_PTR(userdata);
+
+        assert(s);
+        assert(si);
+
+        manager_flush_caches(m, LOG_INFO);
+
+        return 0;
+}
+
+static int manager_sigrtmin1(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
+        Manager *m = ASSERT_PTR(userdata);
+
+        assert(s);
+        assert(si);
+
+        manager_reset_server_features(m);
+        return 0;
+}
+
+static int manager_memory_pressure(sd_event_source *s, void *userdata) {
+        Manager *m = ASSERT_PTR(userdata);
+
+        log_info("Under memory pressure, flushing caches.");
+
+        manager_flush_caches(m, LOG_INFO);
+        sd_event_trim_memory();
+
+        return 0;
+}
+
+static int manager_memory_pressure_listen(Manager *m) {
+        int r;
+
+        assert(m);
+
+        r = sd_event_add_memory_pressure(m->event, NULL, manager_memory_pressure, m);
+        if (r < 0)
+                log_full_errno(ERRNO_IS_NOT_SUPPORTED(r) || ERRNO_IS_PRIVILEGE(r) || (r == -EHOSTDOWN )? LOG_DEBUG : LOG_NOTICE, r,
+                               "Failed to install memory pressure event source, ignoring: %m");
+
+        return 0;
+}
+
+int manager_new(Manager **ret) {
+        _cleanup_(manager_freep) Manager *m = NULL;
+        int r;
+
+        assert(ret);
+
+        m = new(Manager, 1);
+        if (!m)
+                return -ENOMEM;
+
+        *m = (Manager) {
+                .llmnr_ipv4_udp_fd = -EBADF,
+                .llmnr_ipv6_udp_fd = -EBADF,
+                .llmnr_ipv4_tcp_fd = -EBADF,
+                .llmnr_ipv6_tcp_fd = -EBADF,
+                .mdns_ipv4_fd = -EBADF,
+                .mdns_ipv6_fd = -EBADF,
+                .hostname_fd = -EBADF,
+
+                .llmnr_support = DEFAULT_LLMNR_MODE,
+                .mdns_support = DEFAULT_MDNS_MODE,
+                .dnssec_mode = DEFAULT_DNSSEC_MODE,
+                .dns_over_tls_mode = DEFAULT_DNS_OVER_TLS_MODE,
+                .enable_cache = DNS_CACHE_MODE_YES,
+                .dns_stub_listener_mode = DNS_STUB_LISTENER_YES,
+                .read_resolv_conf = true,
+                .need_builtin_fallbacks = true,
+                .etc_hosts_last = USEC_INFINITY,
+                .read_etc_hosts = true,
+
+                .sigrtmin18_info.memory_pressure_handler = manager_memory_pressure,
+                .sigrtmin18_info.memory_pressure_userdata = m,
+        };
+
+        r = dns_trust_anchor_load(&m->trust_anchor);
+        if (r < 0)
+                return r;
+
+        r = manager_parse_config_file(m);
+        if (r < 0)
+                log_warning_errno(r, "Failed to parse configuration file: %m");
+
+#if ENABLE_DNS_OVER_TLS
+        r = dnstls_manager_init(m);
+        if (r < 0)
+                return r;
+#endif
+
+        r = sd_event_default(&m->event);
+        if (r < 0)
+                return r;
+
+        (void) sd_event_add_signal(m->event, NULL, SIGTERM, NULL,  NULL);
+        (void) sd_event_add_signal(m->event, NULL, SIGINT, NULL, NULL);
+
+        (void) sd_event_set_watchdog(m->event, true);
+
+        r = manager_watch_hostname(m);
+        if (r < 0)
+                return r;
+
+        r = dnssd_load(m);
+        if (r < 0)
+                log_warning_errno(r, "Failed to load DNS-SD configuration files: %m");
+
+        r = dns_scope_new(m, &m->unicast_scope, NULL, DNS_PROTOCOL_DNS, AF_UNSPEC);
+        if (r < 0)
+                return r;
+
+        r = manager_network_monitor_listen(m);
+        if (r < 0)
+                return r;
+
+        r = manager_rtnl_listen(m);
+        if (r < 0)
+                return r;
+
+        r = manager_clock_change_listen(m);
+        if (r < 0)
+                return r;
+
+        r = manager_memory_pressure_listen(m);
+        if (r < 0)
+                return r;
+
+        r = manager_connect_bus(m);
+        if (r < 0)
+                return r;
+
+        (void) sd_event_add_signal(m->event, &m->sigusr1_event_source, SIGUSR1, manager_sigusr1, m);
+        (void) sd_event_add_signal(m->event, &m->sigusr2_event_source, SIGUSR2, manager_sigusr2, m);
+        (void) sd_event_add_signal(m->event, &m->sigrtmin1_event_source, SIGRTMIN+1, manager_sigrtmin1, m);
+        (void) sd_event_add_signal(m->event, NULL, SIGRTMIN+18, sigrtmin18_handler, &m->sigrtmin18_info);
+
+        manager_cleanup_saved_user(m);
+
+        *ret = TAKE_PTR(m);
+
+        return 0;
+}
+
+int manager_start(Manager *m) {
+        int r;
+
+        assert(m);
+
+        r = manager_dns_stub_start(m);
+        if (r < 0)
+                return r;
+
+        r = manager_varlink_init(m);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+Manager *manager_free(Manager *m) {
+        Link *l;
+        DnssdService *s;
+
+        if (!m)
+                return NULL;
+
+        dns_server_unlink_all(m->dns_servers);
+        dns_server_unlink_all(m->fallback_dns_servers);
+        dns_search_domain_unlink_all(m->search_domains);
+
+        while ((l = hashmap_first(m->links)))
+               link_free(l);
+
+        while (m->dns_queries)
+                dns_query_free(m->dns_queries);
+
+        m->stub_queries_by_packet = hashmap_free(m->stub_queries_by_packet);
+
+        dns_scope_free(m->unicast_scope);
+
+        /* At this point only orphaned streams should remain. All others should have been freed already by their
+         * owners */
+        while (m->dns_streams)
+                dns_stream_unref(m->dns_streams);
+
+#if ENABLE_DNS_OVER_TLS
+        dnstls_manager_free(m);
+#endif
+
+        hashmap_free(m->links);
+        hashmap_free(m->dns_transactions);
+
+        sd_event_source_unref(m->network_event_source);
+        sd_network_monitor_unref(m->network_monitor);
+
+        sd_netlink_unref(m->rtnl);
+        sd_event_source_unref(m->rtnl_event_source);
+        sd_event_source_unref(m->clock_change_event_source);
+
+        manager_llmnr_stop(m);
+        manager_mdns_stop(m);
+        manager_dns_stub_stop(m);
+        manager_varlink_done(m);
+
+        manager_socket_graveyard_clear(m);
+
+        ordered_set_free(m->dns_extra_stub_listeners);
+
+        bus_verify_polkit_async_registry_free(m->polkit_registry);
+
+        sd_bus_flush_close_unref(m->bus);
+
+        sd_event_source_unref(m->sigusr1_event_source);
+        sd_event_source_unref(m->sigusr2_event_source);
+        sd_event_source_unref(m->sigrtmin1_event_source);
+
+        dns_resource_key_unref(m->llmnr_host_ipv4_key);
+        dns_resource_key_unref(m->llmnr_host_ipv6_key);
+        dns_resource_key_unref(m->mdns_host_ipv4_key);
+        dns_resource_key_unref(m->mdns_host_ipv6_key);
+
+        sd_event_source_unref(m->hostname_event_source);
+        safe_close(m->hostname_fd);
+
+        sd_event_unref(m->event);
+
+        free(m->full_hostname);
+        free(m->llmnr_hostname);
+        free(m->mdns_hostname);
+
+        while ((s = hashmap_first(m->dnssd_services)))
+               dnssd_service_free(s);
+        hashmap_free(m->dnssd_services);
+
+        dns_trust_anchor_flush(&m->trust_anchor);
+        manager_etc_hosts_flush(m);
+
+        return mfree(m);
+}
+
+int manager_recv(Manager *m, int fd, DnsProtocol protocol, DnsPacket **ret) {
+        _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
+        CMSG_BUFFER_TYPE(CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo))
+                         + CMSG_SPACE(int) /* ttl/hoplimit */
+                         + EXTRA_CMSG_SPACE /* kernel appears to require extra buffer space */) control;
+        union sockaddr_union sa;
+        struct iovec iov;
+        struct msghdr mh = {
+                .msg_name = &sa.sa,
+                .msg_namelen = sizeof(sa),
+                .msg_iov = &iov,
+                .msg_iovlen = 1,
+                .msg_control = &control,
+                .msg_controllen = sizeof(control),
+        };
+        struct cmsghdr *cmsg;
+        ssize_t ms, l;
+        int r;
+
+        assert(m);
+        assert(fd >= 0);
+        assert(ret);
+
+        ms = next_datagram_size_fd(fd);
+        if (ms < 0)
+                return ms;
+
+        r = dns_packet_new(&p, protocol, ms, DNS_PACKET_SIZE_MAX);
+        if (r < 0)
+                return r;
+
+        iov = IOVEC_MAKE(DNS_PACKET_DATA(p), p->allocated);
+
+        l = recvmsg_safe(fd, &mh, 0);
+        if (ERRNO_IS_NEG_TRANSIENT(l))
+                return 0;
+        if (l <= 0)
+                return l;
+
+        assert(!(mh.msg_flags & MSG_TRUNC));
+
+        p->size = (size_t) l;
+
+        p->family = sa.sa.sa_family;
+        p->ipproto = IPPROTO_UDP;
+        if (p->family == AF_INET) {
+                p->sender.in = sa.in.sin_addr;
+                p->sender_port = be16toh(sa.in.sin_port);
+        } else if (p->family == AF_INET6) {
+                p->sender.in6 = sa.in6.sin6_addr;
+                p->sender_port = be16toh(sa.in6.sin6_port);
+                p->ifindex = sa.in6.sin6_scope_id;
+        } else
+                return -EAFNOSUPPORT;
+
+        p->timestamp = now(CLOCK_BOOTTIME);
+
+        CMSG_FOREACH(cmsg, &mh) {
+
+                if (cmsg->cmsg_level == IPPROTO_IPV6) {
+                        assert(p->family == AF_INET6);
+
+                        switch (cmsg->cmsg_type) {
+
+                        case IPV6_PKTINFO: {
+                                struct in6_pktinfo *i = CMSG_TYPED_DATA(cmsg, struct in6_pktinfo);
+
+                                if (p->ifindex <= 0)
+                                        p->ifindex = i->ipi6_ifindex;
+
+                                p->destination.in6 = i->ipi6_addr;
+                                break;
+                        }
+
+                        case IPV6_HOPLIMIT:
+                                p->ttl = *CMSG_TYPED_DATA(cmsg, int);
+                                break;
+
+                        case IPV6_RECVFRAGSIZE:
+                                p->fragsize = *CMSG_TYPED_DATA(cmsg, int);
+                                break;
+                        }
+                } else if (cmsg->cmsg_level == IPPROTO_IP) {
+                        assert(p->family == AF_INET);
+
+                        switch (cmsg->cmsg_type) {
+
+                        case IP_PKTINFO: {
+                                struct in_pktinfo *i = CMSG_TYPED_DATA(cmsg, struct in_pktinfo);
+
+                                if (p->ifindex <= 0)
+                                        p->ifindex = i->ipi_ifindex;
+
+                                p->destination.in = i->ipi_addr;
+                                break;
+                        }
+
+                        case IP_TTL:
+                                p->ttl = *CMSG_TYPED_DATA(cmsg, int);
+                                break;
+
+                        case IP_RECVFRAGSIZE:
+                                p->fragsize = *CMSG_TYPED_DATA(cmsg, int);
+                                break;
+                        }
+                }
+        }
+
+        /* The Linux kernel sets the interface index to the loopback
+         * device if the packet came from the local host since it
+         * avoids the routing table in such a case. Let's unset the
+         * interface index in such a case. */
+        if (p->ifindex == LOOPBACK_IFINDEX)
+                p->ifindex = 0;
+
+        if (protocol != DNS_PROTOCOL_DNS) {
+                /* If we don't know the interface index still, we look for the
+                 * first local interface with a matching address. Yuck! */
+                if (p->ifindex <= 0)
+                        p->ifindex = manager_find_ifindex(m, p->family, &p->destination);
+        }
+
+        log_debug("Received %s UDP packet of size %zu, ifindex=%i, ttl=%u, fragsize=%zu, sender=%s, destination=%s",
+                  dns_protocol_to_string(protocol), p->size, p->ifindex, p->ttl, p->fragsize,
+                  IN_ADDR_TO_STRING(p->family, &p->sender),
+                  IN_ADDR_TO_STRING(p->family, &p->destination));
+
+        *ret = TAKE_PTR(p);
+        return 1;
+}
+
+static int sendmsg_loop(int fd, struct msghdr *mh, int flags) {
+        usec_t end;
+        int r;
+
+        assert(fd >= 0);
+        assert(mh);
+
+        end = usec_add(now(CLOCK_MONOTONIC), SEND_TIMEOUT_USEC);
+
+        for (;;) {
+                if (sendmsg(fd, mh, flags) >= 0)
+                        return 0;
+                if (errno == EINTR)
+                        continue;
+                if (errno != EAGAIN)
+                        return -errno;
+
+                r = fd_wait_for_event(fd, POLLOUT, LESS_BY(end, now(CLOCK_MONOTONIC)));
+                if (ERRNO_IS_NEG_TRANSIENT(r))
+                        continue;
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        return -ETIMEDOUT;
+        }
+}
+
+static int write_loop(int fd, void *message, size_t length) {
+        usec_t end;
+        int r;
+
+        assert(fd >= 0);
+        assert(message);
+
+        end = usec_add(now(CLOCK_MONOTONIC), SEND_TIMEOUT_USEC);
+
+        for (;;) {
+                if (write(fd, message, length) >= 0)
+                        return 0;
+                if (errno == EINTR)
+                        continue;
+                if (errno != EAGAIN)
+                        return -errno;
+
+                r = fd_wait_for_event(fd, POLLOUT, LESS_BY(end, now(CLOCK_MONOTONIC)));
+                if (ERRNO_IS_NEG_TRANSIENT(r))
+                        continue;
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        return -ETIMEDOUT;
+        }
+}
+
+int manager_write(Manager *m, int fd, DnsPacket *p) {
+        int r;
+
+        log_debug("Sending %s%s packet with id %" PRIu16 " of size %zu.",
+                  DNS_PACKET_TC(p) ? "truncated (!) " : "",
+                  DNS_PACKET_QR(p) ? "response" : "query",
+                  DNS_PACKET_ID(p),
+                  p->size);
+
+        r = write_loop(fd, DNS_PACKET_DATA(p), p->size);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+static int manager_ipv4_send(
+                Manager *m,
+                int fd,
+                int ifindex,
+                const struct in_addr *destination,
+                uint16_t port,
+                const struct in_addr *source,
+                DnsPacket *p) {
+
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct in_pktinfo))) control = {};
+        union sockaddr_union sa;
+        struct iovec iov;
+        struct msghdr mh = {
+                .msg_iov = &iov,
+                .msg_iovlen = 1,
+                .msg_name = &sa.sa,
+                .msg_namelen = sizeof(sa.in),
+        };
+
+        assert(m);
+        assert(fd >= 0);
+        assert(destination);
+        assert(port > 0);
+        assert(p);
+
+        iov = IOVEC_MAKE(DNS_PACKET_DATA(p), p->size);
+
+        sa = (union sockaddr_union) {
+                .in.sin_family = AF_INET,
+                .in.sin_addr = *destination,
+                .in.sin_port = htobe16(port),
+        };
+
+        if (ifindex > 0) {
+                struct cmsghdr *cmsg;
+                struct in_pktinfo *pi;
+
+                mh.msg_control = &control;
+                mh.msg_controllen = sizeof(control);
+
+                cmsg = CMSG_FIRSTHDR(&mh);
+                cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
+                cmsg->cmsg_level = IPPROTO_IP;
+                cmsg->cmsg_type = IP_PKTINFO;
+
+                pi = CMSG_TYPED_DATA(cmsg, struct in_pktinfo);
+                pi->ipi_ifindex = ifindex;
+
+                if (source)
+                        pi->ipi_spec_dst = *source;
+        }
+
+        return sendmsg_loop(fd, &mh, 0);
+}
+
+static int manager_ipv6_send(
+                Manager *m,
+                int fd,
+                int ifindex,
+                const struct in6_addr *destination,
+                uint16_t port,
+                const struct in6_addr *source,
+                DnsPacket *p) {
+
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct in6_pktinfo))) control = {};
+        union sockaddr_union sa;
+        struct iovec iov;
+        struct msghdr mh = {
+                .msg_iov = &iov,
+                .msg_iovlen = 1,
+                .msg_name = &sa.sa,
+                .msg_namelen = sizeof(sa.in6),
+        };
+
+        assert(m);
+        assert(fd >= 0);
+        assert(destination);
+        assert(port > 0);
+        assert(p);
+
+        iov = IOVEC_MAKE(DNS_PACKET_DATA(p), p->size);
+
+        sa = (union sockaddr_union) {
+                .in6.sin6_family = AF_INET6,
+                .in6.sin6_addr = *destination,
+                .in6.sin6_port = htobe16(port),
+                .in6.sin6_scope_id = ifindex,
+        };
+
+        if (ifindex > 0) {
+                struct cmsghdr *cmsg;
+                struct in6_pktinfo *pi;
+
+                mh.msg_control = &control;
+                mh.msg_controllen = sizeof(control);
+
+                cmsg = CMSG_FIRSTHDR(&mh);
+                cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
+                cmsg->cmsg_level = IPPROTO_IPV6;
+                cmsg->cmsg_type = IPV6_PKTINFO;
+
+                pi = CMSG_TYPED_DATA(cmsg, struct in6_pktinfo);
+                pi->ipi6_ifindex = ifindex;
+
+                if (source)
+                        pi->ipi6_addr = *source;
+        }
+
+        return sendmsg_loop(fd, &mh, 0);
+}
+
+static int dns_question_to_json(DnsQuestion *q, JsonVariant **ret) {
+        _cleanup_(json_variant_unrefp) JsonVariant *l = NULL;
+        DnsResourceKey *key;
+        int r;
+
+        assert(ret);
+
+        DNS_QUESTION_FOREACH(key, q) {
+                _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
+
+                r = dns_resource_key_to_json(key, &v);
+                if (r < 0)
+                        return r;
+
+                r = json_variant_append_array(&l, v);
+                if (r < 0)
+                        return r;
+        }
+
+        *ret = TAKE_PTR(l);
+        return 0;
+}
+
+int manager_monitor_send(
+                Manager *m,
+                int state,
+                int rcode,
+                int error,
+                DnsQuestion *question_idna,
+                DnsQuestion *question_utf8,
+                DnsPacket *question_bypass,
+                DnsQuestion *collected_questions,
+                DnsAnswer *answer) {
+
+        _cleanup_(json_variant_unrefp) JsonVariant *jquestion = NULL, *jcollected_questions = NULL, *janswer = NULL;
+        _cleanup_(dns_question_unrefp) DnsQuestion *merged = NULL;
+        Varlink *connection;
+        DnsAnswerItem *rri;
+        int r;
+
+        assert(m);
+
+        if (set_isempty(m->varlink_subscription))
+                return 0;
+
+        /* Merge all questions into one */
+        r = dns_question_merge(question_idna, question_utf8, &merged);
+        if (r < 0)
+                return log_error_errno(r, "Failed to merge UTF8/IDNA questions: %m");
+
+        if (question_bypass) {
+                _cleanup_(dns_question_unrefp) DnsQuestion *merged2 = NULL;
+
+                r = dns_question_merge(merged, question_bypass->question, &merged2);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to merge UTF8/IDNA questions and DNS packet question: %m");
+
+                dns_question_unref(merged);
+                merged = TAKE_PTR(merged2);
+        }
+
+        /* Convert the current primary question to JSON */
+        r = dns_question_to_json(merged, &jquestion);
+        if (r < 0)
+                return log_error_errno(r, "Failed to convert question to JSON: %m");
+
+        /* Generate a JSON array of the questions preceding the current one in the CNAME chain */
+        r = dns_question_to_json(collected_questions, &jcollected_questions);
+        if (r < 0)
+                return log_error_errno(r, "Failed to convert question to JSON: %m");
+
+        DNS_ANSWER_FOREACH_ITEM(rri, answer) {
+                _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
+
+                r = dns_resource_record_to_json(rri->rr, &v);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to convert answer resource record to JSON: %m");
+
+                r = dns_resource_record_to_wire_format(rri->rr, /* canonical= */ false); /* don't use DNSSEC canonical format, since it removes casing, but we want that for DNS_SD compat */
+                if (r < 0)
+                        return log_error_errno(r, "Failed to generate RR wire format: %m");
+
+                r = json_variant_append_arrayb(
+                                &janswer,
+                                JSON_BUILD_OBJECT(
+                                                JSON_BUILD_PAIR_CONDITION(v, "rr", JSON_BUILD_VARIANT(v)),
+                                                JSON_BUILD_PAIR("raw", JSON_BUILD_BASE64(rri->rr->wire_format, rri->rr->wire_format_size)),
+                                                JSON_BUILD_PAIR_CONDITION(rri->ifindex > 0, "ifindex", JSON_BUILD_INTEGER(rri->ifindex))));
+                if (r < 0)
+                        return log_debug_errno(r, "Failed to append notification entry to array: %m");
+        }
+
+        SET_FOREACH(connection, m->varlink_subscription) {
+                r = varlink_notifyb(connection,
+                                    JSON_BUILD_OBJECT(JSON_BUILD_PAIR("state", JSON_BUILD_STRING(dns_transaction_state_to_string(state))),
+                                                      JSON_BUILD_PAIR_CONDITION(state == DNS_TRANSACTION_RCODE_FAILURE, "rcode", JSON_BUILD_INTEGER(rcode)),
+                                                      JSON_BUILD_PAIR_CONDITION(state == DNS_TRANSACTION_ERRNO, "errno", JSON_BUILD_INTEGER(error)),
+                                                      JSON_BUILD_PAIR("question", JSON_BUILD_VARIANT(jquestion)),
+                                                      JSON_BUILD_PAIR_CONDITION(jcollected_questions, "collectedQuestions", JSON_BUILD_VARIANT(jcollected_questions)),
+                                                      JSON_BUILD_PAIR_CONDITION(janswer, "answer", JSON_BUILD_VARIANT(janswer))));
+                if (r < 0)
+                        log_debug_errno(r, "Failed to send monitor event, ignoring: %m");
+        }
+
+        return 0;
+}
+
+int manager_send(
+                Manager *m,
+                int fd,
+                int ifindex,
+                int family,
+                const union in_addr_union *destination,
+                uint16_t port,
+                const union in_addr_union *source,
+                DnsPacket *p) {
+
+        assert(m);
+        assert(fd >= 0);
+        assert(destination);
+        assert(port > 0);
+        assert(p);
+
+        /* For mDNS, it is natural that the packet have truncated flag when we have many known answers. */
+        bool truncated = DNS_PACKET_TC(p) && (p->protocol != DNS_PROTOCOL_MDNS || !p->more);
+
+        log_debug("Sending %s%s packet with id %" PRIu16 " on interface %i/%s of size %zu.",
+                  truncated ? "truncated (!) " : "",
+                  DNS_PACKET_QR(p) ? "response" : "query",
+                  DNS_PACKET_ID(p),
+                  ifindex, af_to_name(family),
+                  p->size);
+
+        if (family == AF_INET)
+                return manager_ipv4_send(m, fd, ifindex, &destination->in, port, source ? &source->in : NULL, p);
+        if (family == AF_INET6)
+                return manager_ipv6_send(m, fd, ifindex, &destination->in6, port, source ? &source->in6 : NULL, p);
+
+        return -EAFNOSUPPORT;
+}
+
+uint32_t manager_find_mtu(Manager *m) {
+        uint32_t mtu = 0;
+        Link *l;
+
+        /* If we don't know on which link a DNS packet would be delivered, let's find the largest MTU that
+         * works on all interfaces we know of that have an IP address associated */
+
+        HASHMAP_FOREACH(l, m->links) {
+                /* Let's filter out links without IP addresses (e.g. AF_CAN links and suchlike) */
+                if (!l->addresses)
+                        continue;
+
+                /* Safety check: MTU shorter than what we need for the absolutely shortest DNS request? Then
+                 * let's ignore this link. */
+                if (l->mtu < MIN(UDP4_PACKET_HEADER_SIZE + DNS_PACKET_HEADER_SIZE,
+                                 UDP6_PACKET_HEADER_SIZE + DNS_PACKET_HEADER_SIZE))
+                        continue;
+
+                if (mtu <= 0 || l->mtu < mtu)
+                        mtu = l->mtu;
+        }
+
+        if (mtu == 0) /* found nothing? then let's assume the typical Ethernet MTU for lack of anything more precise */
+                return 1500;
+
+        return mtu;
+}
+
+int manager_find_ifindex(Manager *m, int family, const union in_addr_union *in_addr) {
+        LinkAddress *a;
+
+        assert(m);
+
+        if (!IN_SET(family, AF_INET, AF_INET6))
+                return 0;
+
+        if (!in_addr)
+                return 0;
+
+        a = manager_find_link_address(m, family, in_addr);
+        if (a)
+                return a->link->ifindex;
+
+        return 0;
+}
+
+void manager_refresh_rrs(Manager *m) {
+        Link *l;
+        DnssdService *s;
+
+        assert(m);
+
+        m->llmnr_host_ipv4_key = dns_resource_key_unref(m->llmnr_host_ipv4_key);
+        m->llmnr_host_ipv6_key = dns_resource_key_unref(m->llmnr_host_ipv6_key);
+        m->mdns_host_ipv4_key = dns_resource_key_unref(m->mdns_host_ipv4_key);
+        m->mdns_host_ipv6_key = dns_resource_key_unref(m->mdns_host_ipv6_key);
+
+        HASHMAP_FOREACH(l, m->links)
+                link_add_rrs(l, true);
+
+        if (m->mdns_support == RESOLVE_SUPPORT_YES)
+                HASHMAP_FOREACH(s, m->dnssd_services)
+                        if (dnssd_update_rrs(s) < 0)
+                                log_warning("Failed to refresh DNS-SD service '%s'", s->name);
+
+        HASHMAP_FOREACH(l, m->links)
+                link_add_rrs(l, false);
+}
+
+static int manager_next_random_name(const char *old, char **ret_new) {
+        const char *p;
+        uint64_t u, a;
+        char *n;
+
+        p = strchr(old, 0);
+        assert(p);
+
+        while (p > old) {
+                if (!ascii_isdigit(p[-1]))
+                        break;
+
+                p--;
+        }
+
+        if (*p == 0 || safe_atou64(p, &u) < 0 || u <= 0)
+                u = 1;
+
+        /* Add a random number to the old value. This way we can avoid
+         * that two hosts pick the same hostname, win on IPv4 and lose
+         * on IPv6 (or vice versa), and pick the same hostname
+         * replacement hostname, ad infinitum. We still want the
+         * numbers to go up monotonically, hence we just add a random
+         * value 1..10 */
+
+        random_bytes(&a, sizeof(a));
+        u += 1 + a % 10;
+
+        if (asprintf(&n, "%.*s%" PRIu64, (int) (p - old), old, u) < 0)
+                return -ENOMEM;
+
+        *ret_new = n;
+
+        return 0;
+}
+
+int manager_next_hostname(Manager *m) {
+        _cleanup_free_ char *h = NULL, *k = NULL;
+        int r;
+
+        assert(m);
+
+        r = manager_next_random_name(m->llmnr_hostname, &h);
+        if (r < 0)
+                return r;
+
+        r = dns_name_concat(h, "local", 0, &k);
+        if (r < 0)
+                return r;
+
+        log_info("Hostname conflict, changing published hostname from '%s' to '%s'.", m->llmnr_hostname, h);
+
+        free_and_replace(m->llmnr_hostname, h);
+        free_and_replace(m->mdns_hostname, k);
+
+        manager_refresh_rrs(m);
+        (void) manager_send_changed(m, "LLMNRHostname");
+
+        return 0;
+}
+
+LinkAddress* manager_find_link_address(Manager *m, int family, const union in_addr_union *in_addr) {
+        Link *l;
+
+        assert(m);
+
+        if (!IN_SET(family, AF_INET, AF_INET6))
+                return NULL;
+
+        if (!in_addr)
+                return NULL;
+
+        HASHMAP_FOREACH(l, m->links) {
+                LinkAddress *a;
+
+                a = link_find_address(l, family, in_addr);
+                if (a)
+                        return a;
+        }
+
+        return NULL;
+}
+
+bool manager_packet_from_local_address(Manager *m, DnsPacket *p) {
+        assert(m);
+        assert(p);
+
+        /* Let's see if this packet comes from an IP address we have on any local interface */
+
+        return !!manager_find_link_address(m, p->family, &p->sender);
+}
+
+bool manager_packet_from_our_transaction(Manager *m, DnsPacket *p) {
+        DnsTransaction *t;
+
+        assert(m);
+        assert(p);
+
+        /* Let's see if we have a transaction with a query message with the exact same binary contents as the
+         * one we just got. If so, it's almost definitely a packet loop of some kind. */
+
+        t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
+        if (!t)
+                return false;
+
+        return t->sent && dns_packet_equal(t->sent, p);
+}
+
+DnsScope* manager_find_scope(Manager *m, DnsPacket *p) {
+        Link *l;
+
+        assert(m);
+        assert(p);
+
+        l = hashmap_get(m->links, INT_TO_PTR(p->ifindex));
+        if (!l)
+                return NULL;
+
+        switch (p->protocol) {
+        case DNS_PROTOCOL_LLMNR:
+                if (p->family == AF_INET)
+                        return l->llmnr_ipv4_scope;
+                else if (p->family == AF_INET6)
+                        return l->llmnr_ipv6_scope;
+
+                break;
+
+        case DNS_PROTOCOL_MDNS:
+                if (p->family == AF_INET)
+                        return l->mdns_ipv4_scope;
+                else if (p->family == AF_INET6)
+                        return l->mdns_ipv6_scope;
+
+                break;
+
+        default:
+                break;
+        }
+
+        return NULL;
+}
+
+void manager_verify_all(Manager *m) {
+        assert(m);
+
+        LIST_FOREACH(scopes, s, m->dns_scopes)
+                dns_zone_verify_all(&s->zone);
+}
+
+int manager_is_own_hostname(Manager *m, const char *name) {
+        int r;
+
+        assert(m);
+        assert(name);
+
+        if (m->llmnr_hostname) {
+                r = dns_name_equal(name, m->llmnr_hostname);
+                if (r != 0)
+                        return r;
+        }
+
+        if (m->mdns_hostname) {
+                r = dns_name_equal(name, m->mdns_hostname);
+                if (r != 0)
+                        return r;
+        }
+
+        if (m->full_hostname)
+                return dns_name_equal(name, m->full_hostname);
+
+        return 0;
+}
+
+int manager_compile_dns_servers(Manager *m, OrderedSet **dns) {
+        Link *l;
+        int r;
+
+        assert(m);
+        assert(dns);
+
+        r = ordered_set_ensure_allocated(dns, &dns_server_hash_ops);
+        if (r < 0)
+                return r;
+
+        /* First add the system-wide servers and domains */
+        LIST_FOREACH(servers, s, m->dns_servers) {
+                r = ordered_set_put(*dns, s);
+                if (r == -EEXIST)
+                        continue;
+                if (r < 0)
+                        return r;
+        }
+
+        /* Then, add the per-link servers */
+        HASHMAP_FOREACH(l, m->links) {
+                LIST_FOREACH(servers, s, l->dns_servers) {
+                        r = ordered_set_put(*dns, s);
+                        if (r == -EEXIST)
+                                continue;
+                        if (r < 0)
+                                return r;
+                }
+        }
+
+        /* If we found nothing, add the fallback servers */
+        if (ordered_set_isempty(*dns)) {
+                LIST_FOREACH(servers, s, m->fallback_dns_servers) {
+                        r = ordered_set_put(*dns, s);
+                        if (r == -EEXIST)
+                                continue;
+                        if (r < 0)
+                                return r;
+                }
+        }
+
+        return 0;
+}
+
+/* filter_route is a tri-state:
+ *   < 0: no filtering
+ *   = 0 or false: return only domains which should be used for searching
+ *   > 0 or true: return only domains which are for routing only
+ */
+int manager_compile_search_domains(Manager *m, OrderedSet **domains, int filter_route) {
+        Link *l;
+        int r;
+
+        assert(m);
+        assert(domains);
+
+        r = ordered_set_ensure_allocated(domains, &dns_name_hash_ops);
+        if (r < 0)
+                return r;
+
+        LIST_FOREACH(domains, d, m->search_domains) {
+
+                if (filter_route >= 0 &&
+                    d->route_only != !!filter_route)
+                        continue;
+
+                r = ordered_set_put(*domains, d->name);
+                if (r == -EEXIST)
+                        continue;
+                if (r < 0)
+                        return r;
+        }
+
+        HASHMAP_FOREACH(l, m->links) {
+
+                LIST_FOREACH(domains, d, l->search_domains) {
+
+                        if (filter_route >= 0 &&
+                            d->route_only != !!filter_route)
+                                continue;
+
+                        r = ordered_set_put(*domains, d->name);
+                        if (r == -EEXIST)
+                                continue;
+                        if (r < 0)
+                                return r;
+                }
+        }
+
+        return 0;
+}
+
+DnssecMode manager_get_dnssec_mode(Manager *m) {
+        assert(m);
+
+        if (m->dnssec_mode != _DNSSEC_MODE_INVALID)
+                return m->dnssec_mode;
+
+        return DNSSEC_NO;
+}
+
+bool manager_dnssec_supported(Manager *m) {
+        DnsServer *server;
+        Link *l;
+
+        assert(m);
+
+        if (manager_get_dnssec_mode(m) == DNSSEC_NO)
+                return false;
+
+        server = manager_get_dns_server(m);
+        if (server && !dns_server_dnssec_supported(server))
+                return false;
+
+        HASHMAP_FOREACH(l, m->links)
+                if (!link_dnssec_supported(l))
+                        return false;
+
+        return true;
+}
+
+DnsOverTlsMode manager_get_dns_over_tls_mode(Manager *m) {
+        assert(m);
+
+        if (m->dns_over_tls_mode != _DNS_OVER_TLS_MODE_INVALID)
+                return m->dns_over_tls_mode;
+
+        return DNS_OVER_TLS_NO;
+}
+
+void manager_dnssec_verdict(Manager *m, DnssecVerdict verdict, const DnsResourceKey *key) {
+
+        assert(verdict >= 0);
+        assert(verdict < _DNSSEC_VERDICT_MAX);
+
+        if (DEBUG_LOGGING) {
+                char s[DNS_RESOURCE_KEY_STRING_MAX];
+
+                log_debug("Found verdict for lookup %s: %s",
+                          dns_resource_key_to_string(key, s, sizeof s),
+                          dnssec_verdict_to_string(verdict));
+        }
+
+        m->n_dnssec_verdict[verdict]++;
+}
+
+bool manager_routable(Manager *m) {
+        Link *l;
+
+        assert(m);
+
+        /* Returns true if the host has at least one interface with a routable address (regardless if IPv4 or IPv6) */
+
+        HASHMAP_FOREACH(l, m->links)
+                if (link_relevant(l, AF_UNSPEC, false))
+                        return true;
+
+        return false;
+}
+
+void manager_flush_caches(Manager *m, int log_level) {
+        assert(m);
+
+        LIST_FOREACH(scopes, scope, m->dns_scopes)
+                dns_cache_flush(&scope->cache);
+
+        log_full(log_level, "Flushed all caches.");
+}
+
+void manager_reset_server_features(Manager *m) {
+        Link *l;
+
+        dns_server_reset_features_all(m->dns_servers);
+        dns_server_reset_features_all(m->fallback_dns_servers);
+
+        HASHMAP_FOREACH(l, m->links)
+                dns_server_reset_features_all(l->dns_servers);
+
+        log_info("Resetting learnt feature levels on all servers.");
+}
+
+void manager_cleanup_saved_user(Manager *m) {
+        _cleanup_closedir_ DIR *d = NULL;
+
+        assert(m);
+
+        /* Clean up all saved per-link files in /run/systemd/resolve/netif/ that don't have a matching interface
+         * anymore. These files are created to persist settings pushed in by the user via the bus, so that resolved can
+         * be restarted without losing this data. */
+
+        d = opendir("/run/systemd/resolve/netif/");
+        if (!d) {
+                if (errno == ENOENT)
+                        return;
+
+                log_warning_errno(errno, "Failed to open interface directory: %m");
+                return;
+        }
+
+        FOREACH_DIRENT_ALL(de, d, log_error_errno(errno, "Failed to read interface directory: %m")) {
+                _cleanup_free_ char *p = NULL;
+                int ifindex;
+                Link *l;
+
+                if (!IN_SET(de->d_type, DT_UNKNOWN, DT_REG))
+                        continue;
+
+                if (dot_or_dot_dot(de->d_name))
+                        continue;
+
+                ifindex = parse_ifindex(de->d_name);
+                if (ifindex < 0) /* Probably some temporary file from a previous run. Delete it */
+                        goto rm;
+
+                l = hashmap_get(m->links, INT_TO_PTR(ifindex));
+                if (!l) /* link vanished */
+                        goto rm;
+
+                if (l->is_managed) /* now managed by networkd, hence the bus settings are useless */
+                        goto rm;
+
+                continue;
+
+        rm:
+                p = path_join("/run/systemd/resolve/netif", de->d_name);
+                if (!p) {
+                        log_oom();
+                        return;
+                }
+
+                (void) unlink(p);
+        }
+}
+
+bool manager_next_dnssd_names(Manager *m) {
+        DnssdService *s;
+        bool tried = false;
+        int r;
+
+        assert(m);
+
+        HASHMAP_FOREACH(s, m->dnssd_services) {
+                _cleanup_free_ char * new_name = NULL;
+
+                if (!s->withdrawn)
+                        continue;
+
+                r = manager_next_random_name(s->name_template, &new_name);
+                if (r < 0) {
+                        log_warning_errno(r, "Failed to get new name for service '%s': %m", s->name);
+                        continue;
+                }
+
+                free_and_replace(s->name_template, new_name);
+
+                s->withdrawn = false;
+
+                tried = true;
+        }
+
+        if (tried)
+                manager_refresh_rrs(m);
+
+        return tried;
+}
+
+bool manager_server_is_stub(Manager *m, DnsServer *s) {
+        DnsStubListenerExtra *l;
+
+        assert(m);
+        assert(s);
+
+        /* Safety check: we generally already skip the main stub when parsing configuration. But let's be
+         * extra careful, and check here again */
+        if (s->family == AF_INET &&
+            s->address.in.s_addr == htobe32(INADDR_DNS_STUB) &&
+            dns_server_port(s) == 53)
+                return true;
+
+        /* Main reason to call this is to check server data against the extra listeners, and filter things
+         * out. */
+        ORDERED_SET_FOREACH(l, m->dns_extra_stub_listeners)
+                if (s->family == l->family &&
+                    in_addr_equal(s->family, &s->address, &l->address) &&
+                    dns_server_port(s) == dns_stub_listener_extra_port(l))
+                        return true;
+
+        return false;
+}
+
+int socket_disable_pmtud(int fd, int af) {
+        int r;
+
+        assert(fd >= 0);
+
+        if (af == AF_UNSPEC) {
+                af = socket_get_family(fd);
+                if (af < 0)
+                        return af;
+        }
+
+        switch (af) {
+
+        case AF_INET: {
+                /* Turn off path MTU discovery, let's rather fragment on the way than to open us up against
+                 * PMTU forgery vulnerabilities.
+                 *
+                 * There appears to be no documentation about IP_PMTUDISC_OMIT, but it has the effect that
+                 * the "Don't Fragment" bit in the IPv4 header is turned off, thus enforcing fragmentation if
+                 * our datagram size exceeds the MTU of a router in the path, and turning off path MTU
+                 * discovery.
+                 *
+                 * This helps mitigating the PMTUD vulnerability described here:
+                 *
+                 * https://blog.apnic.net/2019/07/12/its-time-to-consider-avoiding-ip-fragmentation-in-the-dns/
+                 *
+                 * Similar logic is in place in most DNS servers.
+                 *
+                 * There are multiple conflicting goals: we want to allow the largest datagrams possible (for
+                 * efficiency reasons), but not have fragmentation (for security reasons), nor use PMTUD (for
+                 * security reasons, too). Our strategy to deal with this is: use large packets, turn off
+                 * PMTUD, but watch fragmentation taking place, and then size our packets to the max of the
+                 * fragments seen — and if we need larger packets always go to TCP.
+                 */
+
+                r = setsockopt_int(fd, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_OMIT);
+                if (r < 0)
+                        return r;
+
+                return 0;
+        }
+
+        case AF_INET6: {
+                /* On IPv6 fragmentation only is done by the sender — never by routers on the path. PMTUD is
+                 * mandatory. If we want to turn off PMTUD, the only way is by sending with minimal MTU only,
+                 * so that we apply maximum fragmentation locally already, and thus PMTUD doesn't happen
+                 * because there's nothing that could be fragmented further anymore. */
+
+                r = setsockopt_int(fd, IPPROTO_IPV6, IPV6_MTU, IPV6_MIN_MTU);
+                if (r < 0)
+                        return r;
+
+                return 0;
+        }
+
+        default:
+                return -EAFNOSUPPORT;
+        }
+}
+
+int dns_manager_dump_statistics_json(Manager *m, JsonVariant **ret) {
+        uint64_t size = 0, hit = 0, miss = 0;
+
+        assert(m);
+        assert(ret);
+
+        LIST_FOREACH(scopes, s, m->dns_scopes) {
+                size += dns_cache_size(&s->cache);
+                hit += s->cache.n_hit;
+                miss += s->cache.n_miss;
+        }
+
+        return json_build(ret,
+                          JSON_BUILD_OBJECT(
+                                        JSON_BUILD_PAIR("transactions", JSON_BUILD_OBJECT(
+                                                JSON_BUILD_PAIR_UNSIGNED("currentTransactions", hashmap_size(m->dns_transactions)),
+                                                JSON_BUILD_PAIR_UNSIGNED("totalTransactions", m->n_transactions_total),
+                                                JSON_BUILD_PAIR_UNSIGNED("totalTimeouts", m->n_timeouts_total),
+                                                JSON_BUILD_PAIR_UNSIGNED("totalTimeoutsServedStale", m->n_timeouts_served_stale_total),
+                                                JSON_BUILD_PAIR_UNSIGNED("totalFailedResponses", m->n_failure_responses_total),
+                                                JSON_BUILD_PAIR_UNSIGNED("totalFailedResponsesServedStale", m->n_failure_responses_served_stale_total)
+                                        )),
+                                        JSON_BUILD_PAIR("cache", JSON_BUILD_OBJECT(
+                                                JSON_BUILD_PAIR_UNSIGNED("size", size),
+                                                JSON_BUILD_PAIR_UNSIGNED("hits", hit),
+                                                JSON_BUILD_PAIR_UNSIGNED("misses", miss)
+                                        )),
+                                        JSON_BUILD_PAIR("dnssec", JSON_BUILD_OBJECT(
+                                                JSON_BUILD_PAIR_UNSIGNED("secure", m->n_dnssec_verdict[DNSSEC_SECURE]),
+                                                JSON_BUILD_PAIR_UNSIGNED("insecure", m->n_dnssec_verdict[DNSSEC_INSECURE]),
+                                                JSON_BUILD_PAIR_UNSIGNED("bogus", m->n_dnssec_verdict[DNSSEC_BOGUS]),
+                                                JSON_BUILD_PAIR_UNSIGNED("indeterminate", m->n_dnssec_verdict[DNSSEC_INDETERMINATE])
+                                        ))));
+}
+
+void dns_manager_reset_statistics(Manager *m) {
+
+        assert(m);
+
+        LIST_FOREACH(scopes, s, m->dns_scopes)
+                s->cache.n_hit = s->cache.n_miss = 0;
+
+        m->n_transactions_total = 0;
+        m->n_timeouts_total = 0;
+        m->n_timeouts_served_stale_total = 0;
+        m->n_failure_responses_total = 0;
+        m->n_failure_responses_served_stale_total = 0;
+        zero(m->n_dnssec_verdict);
+}