Adding upstream version 255.4.upstream/255.4

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

1 files changed, 1531 insertions, 0 deletions

diff --git a/src/network/networkd-ndisc.c b/src/network/networkd-ndisc.c
new file mode 100644
index 0000000..840ccb1
--- /dev/null
+++ b/src/network/networkd-ndisc.c
@@ -0,0 +1,1531 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+  Copyright © 2014 Intel Corporation. All rights reserved.
+***/
+
+#include <arpa/inet.h>
+#include <netinet/icmp6.h>
+#include <linux/if.h>
+#include <linux/if_arp.h>
+
+#include "sd-ndisc.h"
+
+#include "event-util.h"
+#include "missing_network.h"
+#include "networkd-address-generation.h"
+#include "networkd-address.h"
+#include "networkd-dhcp6.h"
+#include "networkd-manager.h"
+#include "networkd-ndisc.h"
+#include "networkd-queue.h"
+#include "networkd-route.h"
+#include "networkd-state-file.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "strv.h"
+#include "sysctl-util.h"
+
+#define NDISC_DNSSL_MAX 64U
+#define NDISC_RDNSS_MAX 64U
+/* Not defined in the RFC, but let's set an upper limit to make not consume much memory.
+ * This should be safe as typically there should be at most 1 portal per network. */
+#define NDISC_CAPTIVE_PORTAL_MAX 64U
+/* Neither defined in the RFC. Just for safety. Otherwise, malformed messages can make clients trigger OOM.
+ * Not sure if the threshold is high enough. Let's adjust later if not. */
+#define NDISC_PREF64_MAX 64U
+
+bool link_ipv6_accept_ra_enabled(Link *link) {
+        assert(link);
+
+        if (!socket_ipv6_is_supported())
+                return false;
+
+        if (link->flags & IFF_LOOPBACK)
+                return false;
+
+        if (link->iftype == ARPHRD_CAN)
+                return false;
+
+        if (!link->network)
+                return false;
+
+        if (!link_may_have_ipv6ll(link, /* check_multicast = */ true))
+                return false;
+
+        assert(link->network->ipv6_accept_ra >= 0);
+        return link->network->ipv6_accept_ra;
+}
+
+void network_adjust_ipv6_accept_ra(Network *network) {
+        assert(network);
+
+        if (!FLAGS_SET(network->link_local, ADDRESS_FAMILY_IPV6)) {
+                if (network->ipv6_accept_ra > 0)
+                        log_warning("%s: IPv6AcceptRA= is enabled but IPv6 link-local addressing is disabled or not supported. "
+                                    "Disabling IPv6AcceptRA=.", network->filename);
+                network->ipv6_accept_ra = false;
+        }
+
+        if (network->ipv6_accept_ra < 0)
+                /* default to accept RA if ip_forward is disabled and ignore RA if ip_forward is enabled */
+                network->ipv6_accept_ra = !FLAGS_SET(network->ip_forward, ADDRESS_FAMILY_IPV6);
+
+        /* When RouterAllowList=, PrefixAllowList= or RouteAllowList= are specified, then
+         * RouterDenyList=, PrefixDenyList= or RouteDenyList= are ignored, respectively. */
+        if (!set_isempty(network->ndisc_allow_listed_router))
+                network->ndisc_deny_listed_router = set_free_free(network->ndisc_deny_listed_router);
+        if (!set_isempty(network->ndisc_allow_listed_prefix))
+                network->ndisc_deny_listed_prefix = set_free_free(network->ndisc_deny_listed_prefix);
+        if (!set_isempty(network->ndisc_allow_listed_route_prefix))
+                network->ndisc_deny_listed_route_prefix = set_free_free(network->ndisc_deny_listed_route_prefix);
+}
+
+static int ndisc_check_ready(Link *link);
+
+static int ndisc_address_ready_callback(Address *address) {
+        Address *a;
+
+        assert(address);
+        assert(address->link);
+
+        SET_FOREACH(a, address->link->addresses)
+                if (a->source == NETWORK_CONFIG_SOURCE_NDISC)
+                        a->callback = NULL;
+
+        return ndisc_check_ready(address->link);
+}
+
+static int ndisc_check_ready(Link *link) {
+        bool found = false, ready = false;
+        Address *address;
+
+        assert(link);
+
+        if (link->ndisc_messages > 0) {
+                log_link_debug(link, "%s(): SLAAC addresses and routes are not set.", __func__);
+                return 0;
+        }
+
+        SET_FOREACH(address, link->addresses) {
+                if (address->source != NETWORK_CONFIG_SOURCE_NDISC)
+                        continue;
+
+                found = true;
+
+                if (address_is_ready(address)) {
+                        ready = true;
+                        break;
+                }
+        }
+
+        if (found && !ready) {
+                SET_FOREACH(address, link->addresses)
+                        if (address->source == NETWORK_CONFIG_SOURCE_NDISC)
+                                address->callback = ndisc_address_ready_callback;
+
+                log_link_debug(link, "%s(): no SLAAC address is ready.", __func__);
+                return 0;
+        }
+
+        link->ndisc_configured = true;
+        log_link_debug(link, "SLAAC addresses and routes set.");
+
+        link_check_ready(link);
+        return 0;
+}
+
+static int ndisc_route_handler(sd_netlink *rtnl, sd_netlink_message *m, Request *req, Link *link, Route *route) {
+        int r;
+
+        assert(link);
+
+        r = route_configure_handler_internal(rtnl, m, link, "Could not set NDisc route");
+        if (r <= 0)
+                return r;
+
+        r = ndisc_check_ready(link);
+        if (r < 0)
+                link_enter_failed(link);
+
+        return 1;
+}
+
+static void ndisc_set_route_priority(Link *link, Route *route) {
+        assert(link);
+        assert(route);
+
+        if (route->priority_set)
+                return; /* explicitly configured. */
+
+        switch (route->pref) {
+        case SD_NDISC_PREFERENCE_LOW:
+                route->priority = link->network->ipv6_accept_ra_route_metric_low;
+                break;
+        case SD_NDISC_PREFERENCE_MEDIUM:
+                route->priority = link->network->ipv6_accept_ra_route_metric_medium;
+                break;
+        case SD_NDISC_PREFERENCE_HIGH:
+                route->priority = link->network->ipv6_accept_ra_route_metric_high;
+                break;
+        default:
+                assert_not_reached();
+        }
+}
+
+static int ndisc_request_route(Route *in, Link *link, sd_ndisc_router *rt) {
+        _cleanup_(route_freep) Route *route = in;
+        struct in6_addr router;
+        uint8_t hop_limit = 0;
+        uint32_t mtu = 0;
+        bool is_new;
+        int r;
+
+        assert(route);
+        assert(link);
+        assert(link->network);
+        assert(rt);
+
+        r = sd_ndisc_router_get_address(rt, &router);
+        if (r < 0)
+                return r;
+
+        if (link->network->ipv6_accept_ra_use_mtu) {
+                r = sd_ndisc_router_get_mtu(rt, &mtu);
+                if (r < 0 && r != -ENODATA)
+                        return log_link_warning_errno(link, r, "Failed to get default router MTU from RA: %m");
+        }
+
+        if (link->network->ipv6_accept_ra_use_hop_limit) {
+                r = sd_ndisc_router_get_hop_limit(rt, &hop_limit);
+                if (r < 0 && r != -ENODATA)
+                        return log_link_warning_errno(link, r, "Failed to get default router hop limit from RA: %m");
+        }
+
+        route->source = NETWORK_CONFIG_SOURCE_NDISC;
+        route->provider.in6 = router;
+        if (!route->table_set)
+                route->table = link_get_ipv6_accept_ra_route_table(link);
+        ndisc_set_route_priority(link, route);
+        if (!route->protocol_set)
+                route->protocol = RTPROT_RA;
+        if (route->quickack < 0)
+                route->quickack = link->network->ipv6_accept_ra_quickack;
+        if (route->mtu == 0)
+                route->mtu = mtu;
+        if (route->hop_limit == 0)
+                route->hop_limit = hop_limit;
+
+        is_new = route_get(NULL, link, route, NULL) < 0;
+
+        r = link_request_route(link, TAKE_PTR(route), true, &link->ndisc_messages,
+                               ndisc_route_handler, NULL);
+        if (r < 0)
+                return r;
+        if (r > 0 && is_new)
+                link->ndisc_configured = false;
+
+        return 0;
+}
+
+static int ndisc_address_handler(sd_netlink *rtnl, sd_netlink_message *m, Request *req, Link *link, Address *address) {
+        int r;
+
+        assert(link);
+
+        r = address_configure_handler_internal(rtnl, m, link, "Could not set NDisc address");
+        if (r <= 0)
+                return r;
+
+        r = ndisc_check_ready(link);
+        if (r < 0)
+                link_enter_failed(link);
+
+        return 1;
+}
+
+static int ndisc_request_address(Address *in, Link *link, sd_ndisc_router *rt) {
+        _cleanup_(address_freep) Address *address = in;
+        struct in6_addr router;
+        bool is_new;
+        int r;
+
+        assert(address);
+        assert(link);
+        assert(rt);
+
+        r = sd_ndisc_router_get_address(rt, &router);
+        if (r < 0)
+                return r;
+
+        address->source = NETWORK_CONFIG_SOURCE_NDISC;
+        address->provider.in6 = router;
+
+        r = free_and_strdup_warn(&address->netlabel, link->network->ndisc_netlabel);
+        if (r < 0)
+                return r;
+
+        is_new = address_get(link, address, NULL) < 0;
+
+        r = link_request_address(link, address, &link->ndisc_messages,
+                                 ndisc_address_handler, NULL);
+        if (r < 0)
+                return r;
+        if (r > 0 && is_new)
+                link->ndisc_configured = false;
+
+        return 0;
+}
+
+static int ndisc_router_process_default(Link *link, sd_ndisc_router *rt) {
+        usec_t lifetime_usec;
+        struct in6_addr gateway;
+        unsigned preference;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(rt);
+
+        if (!link->network->ipv6_accept_ra_use_gateway &&
+            hashmap_isempty(link->network->routes_by_section))
+                return 0;
+
+        r = sd_ndisc_router_get_lifetime_timestamp(rt, CLOCK_BOOTTIME, &lifetime_usec);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get gateway lifetime from RA: %m");
+
+        r = sd_ndisc_router_get_address(rt, &gateway);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get gateway address from RA: %m");
+
+        if (link_get_ipv6_address(link, &gateway, 0, NULL) >= 0) {
+                if (DEBUG_LOGGING)
+                        log_link_debug(link, "No NDisc route added, gateway %s matches local address",
+                                       IN6_ADDR_TO_STRING(&gateway));
+                return 0;
+        }
+
+        r = sd_ndisc_router_get_preference(rt, &preference);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get default router preference from RA: %m");
+
+        if (link->network->ipv6_accept_ra_use_gateway) {
+                _cleanup_(route_freep) Route *route = NULL;
+
+                r = route_new(&route);
+                if (r < 0)
+                        return log_oom();
+
+                route->family = AF_INET6;
+                route->pref = preference;
+                route->gw_family = AF_INET6;
+                route->gw.in6 = gateway;
+                route->lifetime_usec = lifetime_usec;
+
+                r = ndisc_request_route(TAKE_PTR(route), link, rt);
+                if (r < 0)
+                        return log_link_warning_errno(link, r, "Could not request default route: %m");
+        }
+
+        Route *route_gw;
+        HASHMAP_FOREACH(route_gw, link->network->routes_by_section) {
+                _cleanup_(route_freep) Route *route = NULL;
+
+                if (!route_gw->gateway_from_dhcp_or_ra)
+                        continue;
+
+                if (route_gw->gw_family != AF_INET6)
+                        continue;
+
+                r = route_dup(route_gw, &route);
+                if (r < 0)
+                        return r;
+
+                route->gw.in6 = gateway;
+                if (!route->pref_set)
+                        route->pref = preference;
+                route->lifetime_usec = lifetime_usec;
+
+                r = ndisc_request_route(TAKE_PTR(route), link, rt);
+                if (r < 0)
+                        return log_link_warning_errno(link, r, "Could not request gateway: %m");
+        }
+
+        return 0;
+}
+
+static int ndisc_router_process_icmp6_ratelimit(Link *link, sd_ndisc_router *rt) {
+        usec_t icmp6_ratelimit, msec;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(rt);
+
+        if (!link->network->ipv6_accept_ra_use_icmp6_ratelimit)
+                return 0;
+
+        r = sd_ndisc_router_get_icmp6_ratelimit(rt, &icmp6_ratelimit);
+        if (r < 0) {
+                log_link_debug(link, "Failed to get ICMP6 ratelimit from RA, ignoring: %m");
+                return 0;
+        }
+
+        /* We do not allow 0 here. */
+        if (!timestamp_is_set(icmp6_ratelimit))
+                return 0;
+
+        msec = DIV_ROUND_UP(icmp6_ratelimit, USEC_PER_MSEC);
+        if (msec <= 0 || msec > INT_MAX)
+                return 0;
+
+        /* Limit the maximal rates for sending ICMPv6 packets. 0 to disable any limiting, otherwise the
+         * minimal space between responses in milliseconds. Default: 1000. */
+        r = sysctl_write_ip_property_int(AF_INET6, NULL, "icmp/ratelimit", (int) msec);
+        if (r < 0)
+                log_link_warning_errno(link, r, "Failed to apply ICMP6 ratelimit, ignoring: %m");
+
+        return 0;
+}
+
+static int ndisc_router_process_autonomous_prefix(Link *link, sd_ndisc_router *rt) {
+        usec_t lifetime_valid_usec, lifetime_preferred_usec;
+        _cleanup_set_free_ Set *addresses = NULL;
+        struct in6_addr prefix, *a;
+        unsigned prefixlen;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(rt);
+
+        if (!link->network->ipv6_accept_ra_use_autonomous_prefix)
+                return 0;
+
+        r = sd_ndisc_router_prefix_get_address(rt, &prefix);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get prefix address: %m");
+
+        r = sd_ndisc_router_prefix_get_prefixlen(rt, &prefixlen);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get prefix length: %m");
+
+        /* ndisc_generate_addresses() below requires the prefix length <= 64. */
+        if (prefixlen > 64) {
+                log_link_debug(link, "Prefix is longer than 64, ignoring autonomous prefix %s.",
+                               IN6_ADDR_PREFIX_TO_STRING(&prefix, prefixlen));
+                return 0;
+        }
+
+        r = sd_ndisc_router_prefix_get_valid_lifetime_timestamp(rt, CLOCK_BOOTTIME, &lifetime_valid_usec);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get prefix valid lifetime: %m");
+
+        r = sd_ndisc_router_prefix_get_preferred_lifetime_timestamp(rt, CLOCK_BOOTTIME, &lifetime_preferred_usec);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get prefix preferred lifetime: %m");
+
+        /* The preferred lifetime is never greater than the valid lifetime */
+        if (lifetime_preferred_usec > lifetime_valid_usec)
+                return 0;
+
+        r = ndisc_generate_addresses(link, &prefix, prefixlen, &addresses);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to generate SLAAC addresses: %m");
+
+        SET_FOREACH(a, addresses) {
+                _cleanup_(address_freep) Address *address = NULL;
+
+                r = address_new(&address);
+                if (r < 0)
+                        return log_oom();
+
+                address->family = AF_INET6;
+                address->in_addr.in6 = *a;
+                address->prefixlen = prefixlen;
+                address->flags = IFA_F_NOPREFIXROUTE|IFA_F_MANAGETEMPADDR;
+                address->lifetime_valid_usec = lifetime_valid_usec;
+                address->lifetime_preferred_usec = lifetime_preferred_usec;
+
+                r = ndisc_request_address(TAKE_PTR(address), link, rt);
+                if (r < 0)
+                        return log_link_warning_errno(link, r, "Could not request SLAAC address: %m");
+        }
+
+        return 0;
+}
+
+static int ndisc_router_process_onlink_prefix(Link *link, sd_ndisc_router *rt) {
+        _cleanup_(route_freep) Route *route = NULL;
+        unsigned prefixlen, preference;
+        usec_t lifetime_usec;
+        struct in6_addr prefix;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(rt);
+
+        if (!link->network->ipv6_accept_ra_use_onlink_prefix)
+                return 0;
+
+        r = sd_ndisc_router_prefix_get_valid_lifetime_timestamp(rt, CLOCK_BOOTTIME, &lifetime_usec);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get prefix lifetime: %m");
+
+        r = sd_ndisc_router_prefix_get_address(rt, &prefix);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get prefix address: %m");
+
+        r = sd_ndisc_router_prefix_get_prefixlen(rt, &prefixlen);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get prefix length: %m");
+
+        /* Prefix Information option does not have preference, hence we use the 'main' preference here */
+        r = sd_ndisc_router_get_preference(rt, &preference);
+        if (r < 0)
+                log_link_warning_errno(link, r, "Failed to get default router preference from RA: %m");
+
+        r = route_new(&route);
+        if (r < 0)
+                return log_oom();
+
+        route->family = AF_INET6;
+        route->dst.in6 = prefix;
+        route->dst_prefixlen = prefixlen;
+        route->pref = preference;
+        route->lifetime_usec = lifetime_usec;
+
+        r = ndisc_request_route(TAKE_PTR(route), link, rt);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Could not request prefix route: %m");
+
+        return 0;
+}
+
+static int ndisc_router_process_prefix(Link *link, sd_ndisc_router *rt) {
+        unsigned prefixlen;
+        struct in6_addr a;
+        uint8_t flags;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(rt);
+
+        r = sd_ndisc_router_prefix_get_address(rt, &a);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get prefix address: %m");
+
+        /* RFC 4861 Section 4.6.2:
+         * A router SHOULD NOT send a prefix option for the link-local prefix and a host SHOULD ignore such
+         * a prefix option. */
+        if (in6_addr_is_link_local(&a)) {
+                log_link_debug(link, "Received link-local prefix, ignoring autonomous prefix.");
+                return 0;
+        }
+
+        r = sd_ndisc_router_prefix_get_prefixlen(rt, &prefixlen);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get prefix length: %m");
+
+        if (in6_prefix_is_filtered(&a, prefixlen, link->network->ndisc_allow_listed_prefix, link->network->ndisc_deny_listed_prefix)) {
+                if (DEBUG_LOGGING)
+                        log_link_debug(link, "Prefix '%s' is %s, ignoring",
+                                       !set_isempty(link->network->ndisc_allow_listed_prefix) ? "not in allow list"
+                                                                                              : "in deny list",
+                                       IN6_ADDR_PREFIX_TO_STRING(&a, prefixlen));
+                return 0;
+        }
+
+        r = sd_ndisc_router_prefix_get_flags(rt, &flags);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get RA prefix flags: %m");
+
+        if (FLAGS_SET(flags, ND_OPT_PI_FLAG_ONLINK)) {
+                r = ndisc_router_process_onlink_prefix(link, rt);
+                if (r < 0)
+                        return r;
+        }
+
+        if (FLAGS_SET(flags, ND_OPT_PI_FLAG_AUTO)) {
+                r = ndisc_router_process_autonomous_prefix(link, rt);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int ndisc_router_process_route(Link *link, sd_ndisc_router *rt) {
+        _cleanup_(route_freep) Route *route = NULL;
+        unsigned preference, prefixlen;
+        struct in6_addr gateway, dst;
+        usec_t lifetime_usec;
+        int r;
+
+        assert(link);
+
+        if (!link->network->ipv6_accept_ra_use_route_prefix)
+                return 0;
+
+        r = sd_ndisc_router_route_get_lifetime_timestamp(rt, CLOCK_BOOTTIME, &lifetime_usec);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get route lifetime from RA: %m");
+
+        r = sd_ndisc_router_route_get_address(rt, &dst);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get route destination address: %m");
+
+        r = sd_ndisc_router_route_get_prefixlen(rt, &prefixlen);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get route prefix length: %m");
+
+        if (in6_addr_is_null(&dst) && prefixlen == 0) {
+                log_link_debug(link, "Route prefix is ::/0, ignoring");
+                return 0;
+        }
+
+        if (in6_prefix_is_filtered(&dst, prefixlen,
+                                   link->network->ndisc_allow_listed_route_prefix,
+                                   link->network->ndisc_deny_listed_route_prefix)) {
+
+                if (DEBUG_LOGGING)
+                        log_link_debug(link, "Route prefix %s is %s, ignoring",
+                                       !set_isempty(link->network->ndisc_allow_listed_route_prefix) ? "not in allow list"
+                                                                                                    : "in deny list",
+                                       IN6_ADDR_PREFIX_TO_STRING(&dst, prefixlen));
+                return 0;
+        }
+
+        r = sd_ndisc_router_get_address(rt, &gateway);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get gateway address from RA: %m");
+
+        if (link_get_ipv6_address(link, &gateway, 0, NULL) >= 0) {
+                if (DEBUG_LOGGING)
+                        log_link_debug(link, "Advertised route gateway %s is local to the link, ignoring route",
+                                       IN6_ADDR_TO_STRING(&gateway));
+                return 0;
+        }
+
+        r = sd_ndisc_router_route_get_preference(rt, &preference);
+        if (r == -ENOTSUP) {
+                log_link_debug_errno(link, r, "Received route prefix with unsupported preference, ignoring: %m");
+                return 0;
+        }
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get default router preference from RA: %m");
+
+        r = route_new(&route);
+        if (r < 0)
+                return log_oom();
+
+        route->family = AF_INET6;
+        route->pref = preference;
+        route->gw.in6 = gateway;
+        route->gw_family = AF_INET6;
+        route->dst.in6 = dst;
+        route->dst_prefixlen = prefixlen;
+        route->lifetime_usec = lifetime_usec;
+
+        r = ndisc_request_route(TAKE_PTR(route), link, rt);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Could not request additional route: %m");
+
+        return 0;
+}
+
+static void ndisc_rdnss_hash_func(const NDiscRDNSS *x, struct siphash *state) {
+        siphash24_compress(&x->address, sizeof(x->address), state);
+}
+
+static int ndisc_rdnss_compare_func(const NDiscRDNSS *a, const NDiscRDNSS *b) {
+        return memcmp(&a->address, &b->address, sizeof(a->address));
+}
+
+DEFINE_PRIVATE_HASH_OPS_WITH_KEY_DESTRUCTOR(
+                ndisc_rdnss_hash_ops,
+                NDiscRDNSS,
+                ndisc_rdnss_hash_func,
+                ndisc_rdnss_compare_func,
+                free);
+
+static int ndisc_router_process_rdnss(Link *link, sd_ndisc_router *rt) {
+        usec_t lifetime_usec;
+        const struct in6_addr *a;
+        struct in6_addr router;
+        bool updated = false, logged_about_too_many = false;
+        int n, r;
+
+        assert(link);
+        assert(link->network);
+        assert(rt);
+
+        if (!link->network->ipv6_accept_ra_use_dns)
+                return 0;
+
+        r = sd_ndisc_router_get_address(rt, &router);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get router address from RA: %m");
+
+        r = sd_ndisc_router_rdnss_get_lifetime_timestamp(rt, CLOCK_BOOTTIME, &lifetime_usec);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get RDNSS lifetime: %m");
+
+        n = sd_ndisc_router_rdnss_get_addresses(rt, &a);
+        if (n < 0)
+                return log_link_warning_errno(link, n, "Failed to get RDNSS addresses: %m");
+
+        for (int j = 0; j < n; j++) {
+                _cleanup_free_ NDiscRDNSS *x = NULL;
+                NDiscRDNSS *rdnss, d = {
+                        .address = a[j],
+                };
+
+                if (lifetime_usec == 0) {
+                        /* The entry is outdated. */
+                        free(set_remove(link->ndisc_rdnss, &d));
+                        updated = true;
+                        continue;
+                }
+
+                rdnss = set_get(link->ndisc_rdnss, &d);
+                if (rdnss) {
+                        rdnss->router = router;
+                        rdnss->lifetime_usec = lifetime_usec;
+                        continue;
+                }
+
+                if (set_size(link->ndisc_rdnss) >= NDISC_RDNSS_MAX) {
+                        if (!logged_about_too_many)
+                                log_link_warning(link, "Too many RDNSS records per link. Only first %u records will be used.", NDISC_RDNSS_MAX);
+                        logged_about_too_many = true;
+                        continue;
+                }
+
+                x = new(NDiscRDNSS, 1);
+                if (!x)
+                        return log_oom();
+
+                *x = (NDiscRDNSS) {
+                        .address = a[j],
+                        .router = router,
+                        .lifetime_usec = lifetime_usec,
+                };
+
+                r = set_ensure_consume(&link->ndisc_rdnss, &ndisc_rdnss_hash_ops, TAKE_PTR(x));
+                if (r < 0)
+                        return log_oom();
+                assert(r > 0);
+
+                updated = true;
+        }
+
+        if (updated)
+                link_dirty(link);
+
+        return 0;
+}
+
+static void ndisc_dnssl_hash_func(const NDiscDNSSL *x, struct siphash *state) {
+        siphash24_compress_string(NDISC_DNSSL_DOMAIN(x), state);
+}
+
+static int ndisc_dnssl_compare_func(const NDiscDNSSL *a, const NDiscDNSSL *b) {
+        return strcmp(NDISC_DNSSL_DOMAIN(a), NDISC_DNSSL_DOMAIN(b));
+}
+
+DEFINE_PRIVATE_HASH_OPS_WITH_KEY_DESTRUCTOR(
+                ndisc_dnssl_hash_ops,
+                NDiscDNSSL,
+                ndisc_dnssl_hash_func,
+                ndisc_dnssl_compare_func,
+                free);
+
+static int ndisc_router_process_dnssl(Link *link, sd_ndisc_router *rt) {
+        _cleanup_strv_free_ char **l = NULL;
+        usec_t lifetime_usec;
+        struct in6_addr router;
+        bool updated = false, logged_about_too_many = false;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(rt);
+
+        if (link->network->ipv6_accept_ra_use_domains == DHCP_USE_DOMAINS_NO)
+                return 0;
+
+        r = sd_ndisc_router_get_address(rt, &router);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get router address from RA: %m");
+
+        r = sd_ndisc_router_dnssl_get_lifetime_timestamp(rt, CLOCK_BOOTTIME, &lifetime_usec);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get DNSSL lifetime: %m");
+
+        r = sd_ndisc_router_dnssl_get_domains(rt, &l);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get DNSSL addresses: %m");
+
+        STRV_FOREACH(j, l) {
+                _cleanup_free_ NDiscDNSSL *s = NULL;
+                NDiscDNSSL *dnssl;
+
+                s = malloc0(ALIGN(sizeof(NDiscDNSSL)) + strlen(*j) + 1);
+                if (!s)
+                        return log_oom();
+
+                strcpy(NDISC_DNSSL_DOMAIN(s), *j);
+
+                if (lifetime_usec == 0) {
+                        /* The entry is outdated. */
+                        free(set_remove(link->ndisc_dnssl, s));
+                        updated = true;
+                        continue;
+                }
+
+                dnssl = set_get(link->ndisc_dnssl, s);
+                if (dnssl) {
+                        dnssl->router = router;
+                        dnssl->lifetime_usec = lifetime_usec;
+                        continue;
+                }
+
+                if (set_size(link->ndisc_dnssl) >= NDISC_DNSSL_MAX) {
+                        if (!logged_about_too_many)
+                                log_link_warning(link, "Too many DNSSL records per link. Only first %u records will be used.", NDISC_DNSSL_MAX);
+                        logged_about_too_many = true;
+                        continue;
+                }
+
+                s->router = router;
+                s->lifetime_usec = lifetime_usec;
+
+                r = set_ensure_consume(&link->ndisc_dnssl, &ndisc_dnssl_hash_ops, TAKE_PTR(s));
+                if (r < 0)
+                        return log_oom();
+                assert(r > 0);
+
+                updated = true;
+        }
+
+        if (updated)
+                link_dirty(link);
+
+        return 0;
+}
+
+static NDiscCaptivePortal* ndisc_captive_portal_free(NDiscCaptivePortal *x) {
+        if (!x)
+                return NULL;
+
+        free(x->captive_portal);
+        return mfree(x);
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(NDiscCaptivePortal*, ndisc_captive_portal_free);
+
+static void ndisc_captive_portal_hash_func(const NDiscCaptivePortal *x, struct siphash *state) {
+        assert(x);
+        siphash24_compress_string(x->captive_portal, state);
+}
+
+static int ndisc_captive_portal_compare_func(const NDiscCaptivePortal *a, const NDiscCaptivePortal *b) {
+        assert(a);
+        assert(b);
+        return strcmp_ptr(a->captive_portal, b->captive_portal);
+}
+
+DEFINE_PRIVATE_HASH_OPS_WITH_KEY_DESTRUCTOR(
+                ndisc_captive_portal_hash_ops,
+                NDiscCaptivePortal,
+                ndisc_captive_portal_hash_func,
+                ndisc_captive_portal_compare_func,
+                ndisc_captive_portal_free);
+
+static int ndisc_router_process_captive_portal(Link *link, sd_ndisc_router *rt) {
+        _cleanup_(ndisc_captive_portal_freep) NDiscCaptivePortal *new_entry = NULL;
+        _cleanup_free_ char *captive_portal = NULL;
+        usec_t lifetime_usec;
+        NDiscCaptivePortal *exist;
+        struct in6_addr router;
+        const char *uri;
+        size_t len;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(rt);
+
+        if (!link->network->ipv6_accept_ra_use_captive_portal)
+                return 0;
+
+        r = sd_ndisc_router_get_address(rt, &router);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get router address from RA: %m");
+
+        /* RFC 4861 section 4.2. states that the lifetime in the message header should be used only for the
+         * default gateway, but the captive portal option does not have a lifetime field, hence, we use the
+         * main lifetime for the portal. */
+        r = sd_ndisc_router_get_lifetime_timestamp(rt, CLOCK_BOOTTIME, &lifetime_usec);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get lifetime of RA message: %m");
+
+        r = sd_ndisc_router_captive_portal_get_uri(rt, &uri, &len);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get captive portal from RA: %m");
+
+        if (len == 0)
+                return log_link_warning_errno(link, SYNTHETIC_ERRNO(EBADMSG), "Received empty captive portal, ignoring.");
+
+        r = make_cstring(uri, len, MAKE_CSTRING_REFUSE_TRAILING_NUL, &captive_portal);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to convert captive portal URI: %m");
+
+        if (!in_charset(captive_portal, URI_VALID))
+                return log_link_warning_errno(link, SYNTHETIC_ERRNO(EBADMSG), "Received invalid captive portal, ignoring.");
+
+        if (lifetime_usec == 0) {
+                /* Drop the portal with zero lifetime. */
+                ndisc_captive_portal_free(set_remove(link->ndisc_captive_portals,
+                                                     &(NDiscCaptivePortal) {
+                                                             .captive_portal = captive_portal,
+                                                     }));
+                return 0;
+        }
+
+        exist = set_get(link->ndisc_captive_portals,
+                        &(NDiscCaptivePortal) {
+                                .captive_portal = captive_portal,
+                        });
+        if (exist) {
+                /* update existing entry */
+                exist->router = router;
+                exist->lifetime_usec = lifetime_usec;
+                return 1;
+        }
+
+        if (set_size(link->ndisc_captive_portals) >= NDISC_CAPTIVE_PORTAL_MAX) {
+                NDiscCaptivePortal *c, *target = NULL;
+
+                /* Find the portal who has the minimal lifetime and drop it to store new one. */
+                SET_FOREACH(c, link->ndisc_captive_portals)
+                        if (!target || c->lifetime_usec < target->lifetime_usec)
+                                target = c;
+
+                assert(target);
+                assert(set_remove(link->ndisc_captive_portals, target) == target);
+                ndisc_captive_portal_free(target);
+        }
+
+        new_entry = new(NDiscCaptivePortal, 1);
+        if (!new_entry)
+                return log_oom();
+
+        *new_entry = (NDiscCaptivePortal) {
+                .router = router,
+                .lifetime_usec = lifetime_usec,
+                .captive_portal = TAKE_PTR(captive_portal),
+        };
+
+        r = set_ensure_put(&link->ndisc_captive_portals, &ndisc_captive_portal_hash_ops, new_entry);
+        if (r < 0)
+                return log_oom();
+        assert(r > 0);
+        TAKE_PTR(new_entry);
+
+        link_dirty(link);
+        return 1;
+}
+
+static void ndisc_pref64_hash_func(const NDiscPREF64 *x, struct siphash *state) {
+        assert(x);
+
+        siphash24_compress(&x->prefix_len, sizeof(x->prefix_len), state);
+        siphash24_compress(&x->prefix, sizeof(x->prefix), state);
+}
+
+static int ndisc_pref64_compare_func(const NDiscPREF64 *a, const NDiscPREF64 *b) {
+        int r;
+
+        assert(a);
+        assert(b);
+
+        r = CMP(a->prefix_len, b->prefix_len);
+        if (r != 0)
+                return r;
+
+        return memcmp(&a->prefix, &b->prefix, sizeof(a->prefix));
+}
+
+DEFINE_PRIVATE_HASH_OPS_WITH_KEY_DESTRUCTOR(
+                ndisc_pref64_hash_ops,
+                NDiscPREF64,
+                ndisc_pref64_hash_func,
+                ndisc_pref64_compare_func,
+                mfree);
+
+static int ndisc_router_process_pref64(Link *link, sd_ndisc_router *rt) {
+        _cleanup_free_ NDiscPREF64 *new_entry = NULL;
+        usec_t lifetime_usec;
+        struct in6_addr a, router;
+        unsigned prefix_len;
+        NDiscPREF64 *exist;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(rt);
+
+        if (!link->network->ipv6_accept_ra_use_pref64)
+                return 0;
+
+        r = sd_ndisc_router_get_address(rt, &router);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get router address from RA: %m");
+
+        r = sd_ndisc_router_prefix64_get_prefix(rt, &a);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get pref64 prefix: %m");
+
+        r = sd_ndisc_router_prefix64_get_prefixlen(rt, &prefix_len);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get pref64 prefix length: %m");
+
+        r = sd_ndisc_router_prefix64_get_lifetime_timestamp(rt, CLOCK_BOOTTIME, &lifetime_usec);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get pref64 prefix lifetime: %m");
+
+        if (lifetime_usec == 0) {
+                free(set_remove(link->ndisc_pref64,
+                                &(NDiscPREF64) {
+                                        .prefix = a,
+                                        .prefix_len = prefix_len
+                                }));
+                return 0;
+        }
+
+        exist = set_get(link->ndisc_pref64,
+                        &(NDiscPREF64) {
+                                .prefix = a,
+                                .prefix_len = prefix_len
+                });
+        if (exist) {
+                /* update existing entry */
+                exist->router = router;
+                exist->lifetime_usec = lifetime_usec;
+                return 0;
+        }
+
+        if (set_size(link->ndisc_pref64) >= NDISC_PREF64_MAX) {
+                log_link_debug(link, "Too many PREF64 records received. Only first %u records will be used.", NDISC_PREF64_MAX);
+                return 0;
+        }
+
+        new_entry = new(NDiscPREF64, 1);
+        if (!new_entry)
+                return log_oom();
+
+        *new_entry = (NDiscPREF64) {
+                .router = router,
+                .lifetime_usec = lifetime_usec,
+                .prefix = a,
+                .prefix_len = prefix_len,
+        };
+
+        r = set_ensure_put(&link->ndisc_pref64, &ndisc_pref64_hash_ops, new_entry);
+        if (r < 0)
+                return log_oom();
+
+        assert(r > 0);
+        TAKE_PTR(new_entry);
+
+        return 0;
+}
+
+static int ndisc_router_process_options(Link *link, sd_ndisc_router *rt) {
+        size_t n_captive_portal = 0;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(rt);
+
+        for (r = sd_ndisc_router_option_rewind(rt); ; r = sd_ndisc_router_option_next(rt)) {
+                uint8_t type;
+
+                if (r < 0)
+                        return log_link_warning_errno(link, r, "Failed to iterate through options: %m");
+                if (r == 0) /* EOF */
+                        return 0;
+
+                r = sd_ndisc_router_option_get_type(rt, &type);
+                if (r < 0)
+                        return log_link_warning_errno(link, r, "Failed to get RA option type: %m");
+
+                switch (type) {
+                case SD_NDISC_OPTION_PREFIX_INFORMATION:
+                        r = ndisc_router_process_prefix(link, rt);
+                        break;
+
+                case SD_NDISC_OPTION_ROUTE_INFORMATION:
+                        r = ndisc_router_process_route(link, rt);
+                        break;
+
+                case SD_NDISC_OPTION_RDNSS:
+                        r = ndisc_router_process_rdnss(link, rt);
+                        break;
+
+                case SD_NDISC_OPTION_DNSSL:
+                        r = ndisc_router_process_dnssl(link, rt);
+                        break;
+                case SD_NDISC_OPTION_CAPTIVE_PORTAL:
+                        if (n_captive_portal > 0) {
+                                if (n_captive_portal == 1)
+                                        log_link_notice(link, "Received RA with multiple captive portals, only using the first one.");
+
+                                n_captive_portal++;
+                                continue;
+                        }
+                        r = ndisc_router_process_captive_portal(link, rt);
+                        if (r > 0)
+                                n_captive_portal++;
+                        break;
+                case SD_NDISC_OPTION_PREF64:
+                        r = ndisc_router_process_pref64(link, rt);
+                        break;
+                }
+                if (r < 0 && r != -EBADMSG)
+                        return r;
+        }
+}
+
+static int ndisc_drop_outdated(Link *link, usec_t timestamp_usec) {
+        bool updated = false;
+        NDiscDNSSL *dnssl;
+        NDiscRDNSS *rdnss;
+        NDiscCaptivePortal *cp;
+        NDiscPREF64 *p64;
+        Address *address;
+        Route *route;
+        int r = 0, k;
+
+        assert(link);
+
+        /* If an address or friends is already assigned, but not valid anymore, then refuse to update it,
+         * and let's immediately remove it.
+         * See RFC4862, section 5.5.3.e. But the following logic is deviated from RFC4862 by honoring all
+         * valid lifetimes to improve the reaction of SLAAC to renumbering events.
+         * See draft-ietf-6man-slaac-renum-02, section 4.2. */
+
+        SET_FOREACH(route, link->routes) {
+                if (route->source != NETWORK_CONFIG_SOURCE_NDISC)
+                        continue;
+
+                if (route->lifetime_usec >= timestamp_usec)
+                        continue; /* the route is still valid */
+
+                k = route_remove_and_drop(route);
+                if (k < 0)
+                        r = log_link_warning_errno(link, k, "Failed to remove outdated SLAAC route, ignoring: %m");
+        }
+
+        SET_FOREACH(address, link->addresses) {
+                if (address->source != NETWORK_CONFIG_SOURCE_NDISC)
+                        continue;
+
+                if (address->lifetime_valid_usec >= timestamp_usec)
+                        continue; /* the address is still valid */
+
+                k = address_remove_and_drop(address);
+                if (k < 0)
+                        r = log_link_warning_errno(link, k, "Failed to remove outdated SLAAC address, ignoring: %m");
+        }
+
+        SET_FOREACH(rdnss, link->ndisc_rdnss) {
+                if (rdnss->lifetime_usec >= timestamp_usec)
+                        continue; /* the DNS server is still valid */
+
+                free(set_remove(link->ndisc_rdnss, rdnss));
+                updated = true;
+        }
+
+        SET_FOREACH(dnssl, link->ndisc_dnssl) {
+                if (dnssl->lifetime_usec >= timestamp_usec)
+                        continue; /* the DNS domain is still valid */
+
+                free(set_remove(link->ndisc_dnssl, dnssl));
+                updated = true;
+        }
+
+        SET_FOREACH(cp, link->ndisc_captive_portals) {
+                if (cp->lifetime_usec >= timestamp_usec)
+                        continue; /* the captive portal is still valid */
+
+                ndisc_captive_portal_free(set_remove(link->ndisc_captive_portals, cp));
+                updated = true;
+        }
+
+        SET_FOREACH(p64, link->ndisc_pref64) {
+                if (p64->lifetime_usec >= timestamp_usec)
+                        continue; /* the pref64 prefix is still valid */
+
+                free(set_remove(link->ndisc_pref64, p64));
+                /* The pref64 prefix is not exported through the state file, hence it is not necessary to set
+                 * the 'updated' flag. */
+        }
+
+        if (updated)
+                link_dirty(link);
+
+        return r;
+}
+
+static int ndisc_setup_expire(Link *link);
+
+static int ndisc_expire_handler(sd_event_source *s, uint64_t usec, void *userdata) {
+        Link *link = ASSERT_PTR(userdata);
+        usec_t now_usec;
+
+        assert(link->manager);
+
+        assert_se(sd_event_now(link->manager->event, CLOCK_BOOTTIME, &now_usec) >= 0);
+
+        (void) ndisc_drop_outdated(link, now_usec);
+        (void) ndisc_setup_expire(link);
+        return 0;
+}
+
+static int ndisc_setup_expire(Link *link) {
+        usec_t lifetime_usec = USEC_INFINITY;
+        NDiscCaptivePortal *cp;
+        NDiscDNSSL *dnssl;
+        NDiscRDNSS *rdnss;
+        NDiscPREF64 *p64;
+        Address *address;
+        Route *route;
+        int r;
+
+        assert(link);
+        assert(link->manager);
+
+        SET_FOREACH(route, link->routes) {
+                if (route->source != NETWORK_CONFIG_SOURCE_NDISC)
+                        continue;
+
+                if (!route_exists(route))
+                        continue;
+
+                lifetime_usec = MIN(lifetime_usec, route->lifetime_usec);
+        }
+
+        SET_FOREACH(address, link->addresses) {
+                if (address->source != NETWORK_CONFIG_SOURCE_NDISC)
+                        continue;
+
+                if (!address_exists(address))
+                        continue;
+
+                lifetime_usec = MIN(lifetime_usec, address->lifetime_valid_usec);
+        }
+
+        SET_FOREACH(rdnss, link->ndisc_rdnss)
+                lifetime_usec = MIN(lifetime_usec, rdnss->lifetime_usec);
+
+        SET_FOREACH(dnssl, link->ndisc_dnssl)
+                lifetime_usec = MIN(lifetime_usec, dnssl->lifetime_usec);
+
+        SET_FOREACH(cp, link->ndisc_captive_portals)
+                lifetime_usec = MIN(lifetime_usec, cp->lifetime_usec);
+
+        SET_FOREACH(p64, link->ndisc_pref64)
+                lifetime_usec = MIN(lifetime_usec, p64->lifetime_usec);
+
+        if (lifetime_usec == USEC_INFINITY)
+                return 0;
+
+        r = event_reset_time(link->manager->event, &link->ndisc_expire, CLOCK_BOOTTIME,
+                             lifetime_usec, 0, ndisc_expire_handler, link, 0, "ndisc-expiration", true);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to update expiration timer for ndisc: %m");
+
+        return 0;
+}
+
+static int ndisc_start_dhcp6_client(Link *link, sd_ndisc_router *rt) {
+        int r;
+
+        assert(link);
+        assert(link->network);
+
+        switch (link->network->ipv6_accept_ra_start_dhcp6_client) {
+        case IPV6_ACCEPT_RA_START_DHCP6_CLIENT_NO:
+                return 0;
+
+        case IPV6_ACCEPT_RA_START_DHCP6_CLIENT_YES: {
+                uint64_t flags;
+
+                r = sd_ndisc_router_get_flags(rt, &flags);
+                if (r < 0)
+                        return log_link_warning_errno(link, r, "Failed to get RA flags: %m");
+
+                if ((flags & (ND_RA_FLAG_MANAGED | ND_RA_FLAG_OTHER)) == 0)
+                        return 0;
+
+                /* (re)start DHCPv6 client in stateful or stateless mode according to RA flags.
+                 * Note, if both "managed" and "other configuration" bits are set, then ignore
+                 * "other configuration" bit. See RFC 4861. */
+                r = dhcp6_start_on_ra(link, !(flags & ND_RA_FLAG_MANAGED));
+                break;
+        }
+        case IPV6_ACCEPT_RA_START_DHCP6_CLIENT_ALWAYS:
+                /* When IPv6AcceptRA.DHCPv6Client=always, start dhcp6 client in solicit mode
+                 * even if the router flags have neither M nor O flags. */
+                r = dhcp6_start_on_ra(link, /* information_request = */ false);
+                break;
+
+        default:
+                assert_not_reached();
+        }
+
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Could not acquire DHCPv6 lease on NDisc request: %m");
+
+        log_link_debug(link, "Acquiring DHCPv6 lease on NDisc request");
+        return 0;
+}
+
+static int ndisc_router_handler(Link *link, sd_ndisc_router *rt) {
+        struct in6_addr router;
+        usec_t timestamp_usec;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(link->manager);
+        assert(rt);
+
+        r = sd_ndisc_router_get_address(rt, &router);
+        if (r == -ENODATA) {
+                log_link_debug(link, "Received RA without router address, ignoring.");
+                return 0;
+        }
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to get router address from RA: %m");
+
+        if (in6_prefix_is_filtered(&router, 128, link->network->ndisc_allow_listed_router, link->network->ndisc_deny_listed_router)) {
+                if (DEBUG_LOGGING) {
+                        if (!set_isempty(link->network->ndisc_allow_listed_router))
+                                log_link_debug(link, "Router %s is not in allow list, ignoring.", IN6_ADDR_TO_STRING(&router));
+                        else
+                                log_link_debug(link, "Router %s is in deny list, ignoring.", IN6_ADDR_TO_STRING(&router));
+                }
+                return 0;
+        }
+
+        r = sd_ndisc_router_get_timestamp(rt, CLOCK_BOOTTIME, &timestamp_usec);
+        if (r == -ENODATA) {
+                log_link_debug(link, "Received RA without timestamp, ignoring.");
+                return 0;
+        }
+        if (r < 0)
+                return r;
+
+        r = ndisc_drop_outdated(link, timestamp_usec);
+        if (r < 0)
+                return r;
+
+        r = ndisc_start_dhcp6_client(link, rt);
+        if (r < 0)
+                return r;
+
+        r = ndisc_router_process_default(link, rt);
+        if (r < 0)
+                return r;
+
+        r = ndisc_router_process_icmp6_ratelimit(link, rt);
+        if (r < 0)
+                return r;
+
+        r = ndisc_router_process_options(link, rt);
+        if (r < 0)
+                return r;
+
+        r = ndisc_setup_expire(link);
+        if (r < 0)
+                return r;
+
+        if (link->ndisc_messages == 0)
+                link->ndisc_configured = true;
+        else
+                log_link_debug(link, "Setting SLAAC addresses and router.");
+
+        if (!link->ndisc_configured)
+                link_set_state(link, LINK_STATE_CONFIGURING);
+
+        link_check_ready(link);
+        return 0;
+}
+
+static void ndisc_handler(sd_ndisc *nd, sd_ndisc_event_t event, sd_ndisc_router *rt, void *userdata) {
+        Link *link = ASSERT_PTR(userdata);
+        int r;
+
+        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
+                return;
+
+        switch (event) {
+
+        case SD_NDISC_EVENT_ROUTER:
+                r = ndisc_router_handler(link, rt);
+                if (r < 0 && r != -EBADMSG) {
+                        link_enter_failed(link);
+                        return;
+                }
+                break;
+
+        case SD_NDISC_EVENT_TIMEOUT:
+                log_link_debug(link, "NDisc handler get timeout event");
+                if (link->ndisc_messages == 0) {
+                        link->ndisc_configured = true;
+                        link_check_ready(link);
+                }
+                break;
+        default:
+                assert_not_reached();
+        }
+}
+
+static int ndisc_configure(Link *link) {
+        int r;
+
+        assert(link);
+
+        if (!link_ipv6_accept_ra_enabled(link))
+                return 0;
+
+        if (link->ndisc)
+                return -EBUSY; /* Already configured. */
+
+        r = sd_ndisc_new(&link->ndisc);
+        if (r < 0)
+                return r;
+
+        r = sd_ndisc_attach_event(link->ndisc, link->manager->event, 0);
+        if (r < 0)
+                return r;
+
+        if (link->hw_addr.length == ETH_ALEN) {
+                r = sd_ndisc_set_mac(link->ndisc, &link->hw_addr.ether);
+                if (r < 0)
+                        return r;
+        }
+
+        r = sd_ndisc_set_ifindex(link->ndisc, link->ifindex);
+        if (r < 0)
+                return r;
+
+        r = sd_ndisc_set_callback(link->ndisc, ndisc_handler, link);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+int ndisc_start(Link *link) {
+        int r;
+
+        assert(link);
+
+        if (!link->ndisc || !link->dhcp6_client)
+                return 0;
+
+        if (!link_has_carrier(link))
+                return 0;
+
+        if (in6_addr_is_null(&link->ipv6ll_address))
+                return 0;
+
+        log_link_debug(link, "Discovering IPv6 routers");
+
+        r = sd_ndisc_start(link->ndisc);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+static int ndisc_process_request(Request *req, Link *link, void *userdata) {
+        int r;
+
+        assert(link);
+
+        if (!link_is_ready_to_configure(link, /* allow_unmanaged = */ false))
+                return 0;
+
+        r = ndisc_configure(link);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to configure IPv6 Router Discovery: %m");
+
+        r = ndisc_start(link);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to start IPv6 Router Discovery: %m");
+
+        log_link_debug(link, "IPv6 Router Discovery is configured%s.",
+                       r > 0 ? " and started" : "");
+        return 1;
+}
+
+int link_request_ndisc(Link *link) {
+        int r;
+
+        assert(link);
+
+        if (!link_ipv6_accept_ra_enabled(link))
+                return 0;
+
+        if (link->ndisc)
+                return 0;
+
+        r = link_queue_request(link, REQUEST_TYPE_NDISC, ndisc_process_request, NULL);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to request configuring of the IPv6 Router Discovery: %m");
+
+        log_link_debug(link, "Requested configuring of the IPv6 Router Discovery.");
+        return 0;
+}
+
+int ndisc_stop(Link *link) {
+        assert(link);
+
+        link->ndisc_expire = sd_event_source_disable_unref(link->ndisc_expire);
+
+        return sd_ndisc_stop(link->ndisc);
+}
+
+
+void ndisc_flush(Link *link) {
+        assert(link);
+
+        /* Remove all RDNSS, DNSSL, and Captive Portal entries, without exception. */
+
+        link->ndisc_rdnss = set_free(link->ndisc_rdnss);
+        link->ndisc_dnssl = set_free(link->ndisc_dnssl);
+        link->ndisc_captive_portals = set_free(link->ndisc_captive_portals);
+        link->ndisc_pref64 = set_free(link->ndisc_pref64);
+}
+
+static const char* const ipv6_accept_ra_start_dhcp6_client_table[_IPV6_ACCEPT_RA_START_DHCP6_CLIENT_MAX] = {
+        [IPV6_ACCEPT_RA_START_DHCP6_CLIENT_NO]     = "no",
+        [IPV6_ACCEPT_RA_START_DHCP6_CLIENT_ALWAYS] = "always",
+        [IPV6_ACCEPT_RA_START_DHCP6_CLIENT_YES]    = "yes",
+};
+
+DEFINE_PRIVATE_STRING_TABLE_LOOKUP_FROM_STRING_WITH_BOOLEAN(ipv6_accept_ra_start_dhcp6_client, IPv6AcceptRAStartDHCP6Client, IPV6_ACCEPT_RA_START_DHCP6_CLIENT_YES);
+
+DEFINE_CONFIG_PARSE_ENUM(config_parse_ipv6_accept_ra_use_domains, dhcp_use_domains, DHCPUseDomains,
+                         "Failed to parse UseDomains= setting");
+DEFINE_CONFIG_PARSE_ENUM(config_parse_ipv6_accept_ra_start_dhcp6_client, ipv6_accept_ra_start_dhcp6_client, IPv6AcceptRAStartDHCP6Client,
+                         "Failed to parse DHCPv6Client= setting");