resolved: implement D-Bus API for DNS-SD

src/libsystemd/sd-bus/bus-common-errors.h

@@ -83,6 +83,8 @@
 #define BUS_ERROR_NO_SUCH_LINK "org.freedesktop.resolve1.NoSuchLink"
 #define BUS_ERROR_LINK_BUSY "org.freedesktop.resolve1.LinkBusy"
 #define BUS_ERROR_NETWORK_DOWN "org.freedesktop.resolve1.NetworkDown"
+#define BUS_ERROR_NO_SUCH_DNSSD_SERVICE "org.freedesktop.resolve1.NoSuchDnssdService"
+#define BUS_ERROR_DNSSD_SERVICE_EXISTS "org.freedesktop.resolve1.DnssdServiceExists"
 #define _BUS_ERROR_DNS "org.freedesktop.resolve1.DnsError."
 
 #define BUS_ERROR_NO_SUCH_TRANSFER "org.freedesktop.import1.NoSuchTransfer"

src/resolve/meson.build

@@ -37,6 +37,8 @@ systemd_resolved_only_sources = files('''
         resolved-manager.h
         resolved-dnssd.c
         resolved-dnssd.h
+        resolved-dnssd-bus.c
+        resolved-dnssd-bus.h
         resolved-conf.c
         resolved-conf.h
         resolved-resolv-conf.c

src/resolve/resolved-bus.c

@@ -25,7 +25,10 @@
 #include "resolved-bus.h"
 #include "resolved-def.h"
 #include "resolved-dns-synthesize.h"
+#include "resolved-dnssd.h"
+#include "resolved-dnssd-bus.h"
 #include "resolved-link-bus.h"
+#include "utf8.h"
 
 static int reply_query_state(DnsQuery *q) {
 
@@ -1581,6 +1584,177 @@ static int bus_method_reset_server_features(sd_bus_message *message, void *userd
         return sd_bus_reply_method_return(message, NULL);
 }
 
+static int on_bus_track(sd_bus_track *t, void *userdata) {
+        DnssdService *s = userdata;
+
+        assert(t);
+        assert(s);
+
+        log_debug("Client of active request vanished, destroying DNS-SD service.");
+        dnssd_service_free(s);
+
+        return 0;
+}
+
+static int bus_method_register_service(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        _cleanup_(dnssd_service_freep) DnssdService *service = NULL;
+        _cleanup_(sd_bus_track_unrefp) sd_bus_track *bus_track = NULL;
+        _cleanup_free_ char *path = NULL;
+        _cleanup_free_ char *instance_name = NULL;
+        Manager *m = userdata;
+        DnssdService *s = NULL;
+        DnsTxtItem *last = NULL;
+        const char *name;
+        const char *name_template;
+        const char *type;
+        int r;
+
+        assert(message);
+        assert(m);
+
+        if (m->mdns_support != RESOLVE_SUPPORT_YES)
+                return sd_bus_error_setf(error, SD_BUS_ERROR_NOT_SUPPORTED, "Support for MulticastDNS is disabled");
+
+        service = new0(DnssdService, 1);
+        if (!service)
+                return log_oom();
+
+        r = sd_bus_message_read(message, "sssqqq", &name, &name_template, &type,
+                                &service->port, &service->priority,
+                                &service->weight);
+        if (r < 0)
+                return r;
+
+        s = hashmap_get(m->dnssd_services, name);
+        if (s)
+                return sd_bus_error_setf(error, BUS_ERROR_DNSSD_SERVICE_EXISTS, "DNS-SD service '%s' exists already", name);
+
+        if (!dnssd_srv_type_is_valid(type))
+                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "DNS-SD service type '%s' is invalid", type);
+
+        service->name = strdup(name);
+        if (!service->name)
+                return log_oom();
+
+        service->name_template = strdup(name_template);
+        if (!service->name_template)
+                return log_oom();
+
+        service->type = strdup(type);
+        if (!service->type)
+                return log_oom();
+
+        r = dnssd_render_instance_name(service, &instance_name);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_enter_container(message, SD_BUS_TYPE_ARRAY, "{say}");
+        if (r < 0)
+                return sd_bus_error_set_errno(error, r);
+
+        while ((r = sd_bus_message_enter_container(message, SD_BUS_TYPE_DICT_ENTRY, "say")) > 0) {
+                const char *key;
+                const void *value;
+                size_t size;
+                DnsTxtItem *i;
+
+                r = sd_bus_message_read(message, "s", &key);
+                if (r < 0)
+                        return sd_bus_error_set_errno(error, r);
+
+                if (strlen_ptr(key) == 0)
+                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Keys in DNS-SD TXT RRs can't be empty");
+
+                if (!ascii_is_valid(key))
+                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "TXT key '%s' contains non-ASCII symbols", key);
+
+                r = sd_bus_message_read_array(message, 'y', &value, &size);
+                if (r < 0)
+                        return sd_bus_error_set_errno(error, r);
+
+                r = dnssd_txt_item_new_from_data(key, value, size, &i);
+                if (r < 0)
+                        return sd_bus_error_set_errno(error, r);
+
+                LIST_INSERT_AFTER(items, service->txt, last, i);
+                last = i;
+        }
+
+        r = sd_bus_message_exit_container(message);
+        if (r < 0)
+                return sd_bus_error_set_errno(error, r);
+
+        if (!service->txt) {
+                r = dns_txt_item_new_empty(&service->txt);
+                if (r < 0)
+                        return sd_bus_error_set_errno(error, r);
+        }
+
+        r = sd_bus_path_encode("/org/freedesktop/resolve1/dnssd", service->name, &path);
+        if (r < 0)
+                return r;
+
+        r = hashmap_ensure_allocated(&m->dnssd_services, &string_hash_ops);
+        if (r < 0)
+                return r;
+
+        r = hashmap_put(m->dnssd_services, service->name, service);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_track_new(sd_bus_message_get_bus(message), &bus_track, on_bus_track, service);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_track_add_sender(bus_track, message);
+        if (r < 0)
+                return r;
+
+        service->manager = m;
+
+        service = NULL;
+
+        manager_refresh_rrs(m);
+
+        return sd_bus_reply_method_return(message, "o", path);
+}
+
+static int call_dnssd_method(Manager *m, sd_bus_message *message, sd_bus_message_handler_t handler, sd_bus_error *error) {
+        _cleanup_free_ char *name = NULL;
+        DnssdService *s = NULL;
+        const char *path;
+        int r;
+
+        assert(m);
+        assert(message);
+        assert(handler);
+
+        r = sd_bus_message_read(message, "o", &path);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_path_decode(path, "/org/freedesktop/resolve1/dnssd", &name);
+        if (r == 0)
+                return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_DNSSD_SERVICE, "DNS-SD service with object path '%s' does not exist", path);
+        if (r < 0)
+                return r;
+
+        s = hashmap_get(m->dnssd_services, name);
+        if (!s)
+                return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_DNSSD_SERVICE, "DNS-SD service '%s' not known", name);
+
+        return handler(message, s, error);
+}
+
+static int bus_method_unregister_service(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        Manager *m = userdata;
+
+        assert(message);
+        assert(m);
+
+        return call_dnssd_method(m, message, bus_dnssd_method_unregister, error);
+}
+
 static const sd_bus_vtable resolve_vtable[] = {
         SD_BUS_VTABLE_START(0),
         SD_BUS_PROPERTY("LLMNRHostname", "s", NULL, offsetof(Manager, llmnr_hostname), 0),
@@ -1609,6 +1783,8 @@ static const sd_bus_vtable resolve_vtable[] = {
         SD_BUS_METHOD("SetLinkDNSSECNegativeTrustAnchors", "ias", NULL, bus_method_set_link_dnssec_negative_trust_anchors, 0),
         SD_BUS_METHOD("RevertLink", "i", NULL, bus_method_revert_link, 0),
 
+        SD_BUS_METHOD("RegisterService", "sssqqqa{say}", "o", bus_method_register_service, 0),
+        SD_BUS_METHOD("UnregisterService", "o", NULL, bus_method_unregister_service, 0),
         SD_BUS_VTABLE_END,
 };
 
@@ -1681,6 +1857,14 @@ int manager_connect_bus(Manager *m) {
         if (r < 0)
                 return log_error_errno(r, "Failed to register link enumerator: %m");
 
+        r = sd_bus_add_fallback_vtable(m->bus, NULL, "/org/freedesktop/resolve1/dnssd", "org.freedesktop.resolve1.DnssdService", dnssd_vtable, dnssd_object_find, m);
+        if (r < 0)
+                return log_error_errno(r, "Failed to register dnssd objects: %m");
+
+        r = sd_bus_add_node_enumerator(m->bus, NULL, "/org/freedesktop/resolve1/dnssd", dnssd_node_enumerator, m);
+        if (r < 0)
+                return log_error_errno(r, "Failed to register dnssd enumerator: %m");
+
         r = sd_bus_request_name(m->bus, "org.freedesktop.resolve1", 0);
         if (r < 0)
                 return log_error_errno(r, "Failed to register name: %m");

src/resolve/resolved-dns-scope.c

@@ -1205,6 +1205,8 @@ int dns_scope_add_dnssd_services(DnsScope *scope) {
         scope->announced = false;
 
         HASHMAP_FOREACH(service, scope->manager->dnssd_services, i) {
+                service->withdrawn = false;
+
                 r = dns_zone_put(&scope->zone, scope, service->ptr_rr, false);
                 if (r < 0)
                         log_warning_errno(r, "Failed to add PTR record to MDNS zone: %m");

src/resolve/resolved-dns-zone.c

@@ -23,6 +23,7 @@
 #include "list.h"
 #include "resolved-dns-packet.h"
 #include "resolved-dns-zone.h"
+#include "resolved-dnssd.h"
 #include "string-util.h"
 
 /* Never allow more than 1K entries */
@@ -525,6 +526,8 @@ void dns_zone_item_conflict(DnsZoneItem *i) {
         /* Withdraw the conflict item */
         i->state = DNS_ZONE_ITEM_WITHDRAWN;
 
+        dnssd_signal_conflict(i->scope->manager, dns_resource_key_name(i->rr->key));
+
         /* Maybe change the hostname */
         if (manager_is_own_hostname(i->scope->manager, dns_resource_key_name(i->rr->key)) > 0)
                 manager_next_hostname(i->scope->manager);

src/resolve/resolved-dnssd-bus.c

@@ -0,0 +1,132 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2017 Dmitry Rozhkov
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "alloc-util.h"
+#include "resolved-dnssd.h"
+#include "resolved-dnssd-bus.h"
+#include "resolved-link.h"
+#include "strv.h"
+
+int bus_dnssd_method_unregister(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        DnssdService *s = userdata;
+        Manager *m;
+        Iterator i;
+        Link *l;
+        int r;
+
+        assert(message);
+        assert(s);
+
+        m = s->manager;
+
+        HASHMAP_FOREACH(l, m->links, i) {
+                if (l->mdns_ipv4_scope) {
+                        r = dns_scope_announce(l->mdns_ipv4_scope, true);
+                        if (r < 0)
+                                log_warning_errno(r, "Failed to send goodbye messages in IPv4 scope: %m");
+
+                        dns_zone_remove_rr(&l->mdns_ipv4_scope->zone, s->ptr_rr);
+                        dns_zone_remove_rr(&l->mdns_ipv4_scope->zone, s->srv_rr);
+                        dns_zone_remove_rr(&l->mdns_ipv4_scope->zone, s->txt_rr);
+                }
+
+                if (l->mdns_ipv6_scope) {
+                        r = dns_scope_announce(l->mdns_ipv6_scope, true);
+                        if (r < 0)
+                                log_warning_errno(r, "Failed to send goodbye messages in IPv6 scope: %m");
+
+                        dns_zone_remove_rr(&l->mdns_ipv6_scope->zone, s->ptr_rr);
+                        dns_zone_remove_rr(&l->mdns_ipv6_scope->zone, s->srv_rr);
+                        dns_zone_remove_rr(&l->mdns_ipv6_scope->zone, s->txt_rr);
+                }
+        }
+
+        dnssd_service_free(s);
+
+        manager_refresh_rrs(m);
+
+        return sd_bus_reply_method_return(message, NULL);
+}
+
+const sd_bus_vtable dnssd_vtable[] = {
+        SD_BUS_VTABLE_START(0),
+
+        SD_BUS_METHOD("Unregister", NULL, NULL, bus_dnssd_method_unregister, 0),
+        SD_BUS_SIGNAL("Conflicted", NULL, 0),
+
+        SD_BUS_VTABLE_END
+};
+
+int dnssd_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error) {
+        _cleanup_free_ char *name = NULL;
+        Manager *m = userdata;
+        DnssdService *service;
+        int r;
+
+        assert(bus);
+        assert(path);
+        assert(interface);
+        assert(found);
+        assert(m);
+
+        r = sd_bus_path_decode(path, "/org/freedesktop/resolve1/dnssd", &name);
+        if (r <= 0)
+                return 0;
+
+        service = hashmap_get(m->dnssd_services, name);
+        if (!service)
+                return 0;
+
+        *found = service;
+        return 1;
+}
+
+int dnssd_node_enumerator(sd_bus *bus, const char *path, void *userdata, char ***nodes, sd_bus_error *error) {
+        _cleanup_strv_free_ char **l = NULL;
+        Manager *m = userdata;
+        DnssdService *service;
+        Iterator i;
+        unsigned c = 0;
+        int r;
+
+        assert(bus);
+        assert(path);
+        assert(m);
+        assert(nodes);
+
+        l = new0(char*, hashmap_size(m->dnssd_services) + 1);
+        if (!l)
+                return -ENOMEM;
+
+        HASHMAP_FOREACH(service, m->dnssd_services, i) {
+                char *p;
+
+                r = sd_bus_path_encode("/org/freedesktop/resolve1/dnssd", service->name, &p);
+                if (r < 0)
+                        return r;
+
+                l[c++] = p;
+        }
+
+        l[c] = NULL;
+        *nodes = l;
+        l = NULL;
+
+        return 1;
+}

src/resolve/resolved-dnssd-bus.h

@@ -0,0 +1,29 @@
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2017 Dmitry Rozhkov
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "sd-bus.h"
+
+extern const sd_bus_vtable dnssd_vtable[];
+
+int dnssd_object_find(sd_bus *bus, const char *path, const char *interface, void *userdata, void **found, sd_bus_error *error);
+int dnssd_node_enumerator(sd_bus *bus, const char *path, void *userdata, char ***nodes, sd_bus_error *error);
+
+int bus_dnssd_method_unregister(sd_bus_message *message, void *userdata, sd_bus_error *error);

src/resolve/resolved-dnssd.c

@@ -314,3 +314,38 @@ int dnssd_txt_item_new_from_data(const char *key, const void *data, const size_t
 
         return 0;
 }
+
+void dnssd_signal_conflict(Manager *manager, const char *name) {
+        Iterator i;
+        DnssdService *s;
+        int r;
+
+        HASHMAP_FOREACH(s, manager->dnssd_services, i) {
+                if (s->withdrawn)
+                        continue;
+
+                if (dns_name_equal(dns_resource_key_name(s->srv_rr->key), name)) {
+                        _cleanup_free_ char *path = NULL;
+
+                        s->withdrawn = true;
+
+                        r = sd_bus_path_encode("/org/freedesktop/resolve1/dnssd", s->name, &path);
+                        if (r < 0) {
+                                log_error_errno(r, "Can't get D-BUS object path: %m");
+                                return;
+                        }
+
+                        r = sd_bus_emit_signal(manager->bus,
+                                               path,
+                                               "org.freedesktop.resolve1.DnssdService",
+                                               "Conflicted",
+                                               NULL);
+                        if (r < 0) {
+                                log_error_errno(r, "Cannot emit signal: %m");
+                                return;
+                        }
+
+                        break;
+                }
+        }
+}

src/resolve/resolved-dnssd.h

@@ -45,6 +45,8 @@ struct DnssdService {
         DnsResourceRecord *txt_rr;
 
         Manager *manager;
+
+        bool withdrawn:1;
 };
 
 DnssdService *dnssd_service_free(DnssdService *service);
@@ -56,3 +58,4 @@ int dnssd_load(Manager *manager);
 int dnssd_txt_item_new_from_string(const char *key, const char *value, DnsTxtItem **ret_item);
 int dnssd_txt_item_new_from_data(const char *key, const void *value, const size_t size, DnsTxtItem **ret_item);
 int dnssd_update_rrs(DnssdService *s);
+void dnssd_signal_conflict(Manager *manager, const char *name);