Adding upstream version 247.3.upstream/247.3upstream

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

1 files changed, 1761 insertions, 0 deletions

diff --git a/src/network/networkd-dhcp4.c b/src/network/networkd-dhcp4.c
new file mode 100644
index 0000000..f3c1e5f
--- /dev/null
+++ b/src/network/networkd-dhcp4.c
@@ -0,0 +1,1761 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <linux/if.h>
+#include <linux/if_arp.h>
+
+#include "escape.h"
+#include "alloc-util.h"
+#include "dhcp-client-internal.h"
+#include "hostname-util.h"
+#include "parse-util.h"
+#include "network-internal.h"
+#include "networkd-address.h"
+#include "networkd-dhcp4.h"
+#include "networkd-link.h"
+#include "networkd-manager.h"
+#include "networkd-network.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "sysctl-util.h"
+#include "web-util.h"
+
+static int dhcp4_update_address(Link *link, bool announce);
+static int dhcp4_remove_all(Link *link);
+
+static int dhcp4_release_old_lease(Link *link) {
+        Route *route;
+        int k, r = 0;
+
+        assert(link);
+
+        if (!link->dhcp_address_old && set_isempty(link->dhcp_routes_old))
+                return 0;
+
+        log_link_debug(link, "Removing old DHCPv4 address and routes.");
+
+        link_dirty(link);
+
+        SET_FOREACH(route, link->dhcp_routes_old) {
+                k = route_remove(route, NULL, link, NULL);
+                if (k < 0)
+                        r = k;
+        }
+
+        if (link->dhcp_address_old) {
+                k = address_remove(link->dhcp_address_old, link, NULL);
+                if (k < 0)
+                        r = k;
+        }
+
+        return r;
+}
+
+static void dhcp4_check_ready(Link *link) {
+        int r;
+
+        if (link->network->dhcp_send_decline && !link->dhcp4_address_bind)
+                return;
+
+        if (link->dhcp4_messages > 0)
+                return;
+
+        link->dhcp4_configured = true;
+
+        /* New address and routes are configured now. Let's release old lease. */
+        r = dhcp4_release_old_lease(link);
+        if (r < 0) {
+                link_enter_failed(link);
+                return;
+        }
+
+        link_check_ready(link);
+}
+
+static int dhcp4_route_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
+        int r;
+
+        assert(link);
+        assert(link->dhcp4_messages > 0);
+
+        link->dhcp4_messages--;
+
+        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
+                return 1;
+
+        r = sd_netlink_message_get_errno(m);
+        if (r == -ENETUNREACH && !link->dhcp4_route_retrying) {
+
+                /* It seems kernel does not support that the prefix route cannot be configured with
+                 * route table. Let's once drop the config and reconfigure them later. */
+
+                log_link_message_debug_errno(link, m, r, "Could not set DHCPv4 route, retrying later");
+                link->dhcp4_route_failed = true;
+                link->manager->dhcp4_prefix_root_cannot_set_table = true;
+        } else if (r < 0 && r != -EEXIST) {
+                log_link_message_warning_errno(link, m, r, "Could not set DHCPv4 route");
+                link_enter_failed(link);
+                return 1;
+        }
+
+        if (link->dhcp4_messages == 0 && link->dhcp4_route_failed) {
+                link->dhcp4_route_failed = false;
+                link->dhcp4_route_retrying = true;
+
+                r = dhcp4_remove_all(link);
+                if (r < 0)
+                        link_enter_failed(link);
+                return 1;
+        }
+
+        dhcp4_check_ready(link);
+
+        return 1;
+}
+
+static int route_scope_from_address(const Route *route, const struct in_addr *self_addr) {
+        assert(route);
+        assert(self_addr);
+
+        if (in4_addr_is_localhost(&route->dst.in) ||
+            (!in4_addr_is_null(self_addr) && in4_addr_equal(&route->dst.in, self_addr)))
+                return RT_SCOPE_HOST;
+        else if (in4_addr_is_null(&route->gw.in))
+                return RT_SCOPE_LINK;
+        else
+                return RT_SCOPE_UNIVERSE;
+}
+
+static bool link_prefixroute(Link *link) {
+        return !link->network->dhcp_route_table_set ||
+                link->network->dhcp_route_table == RT_TABLE_MAIN ||
+                link->manager->dhcp4_prefix_root_cannot_set_table;
+}
+
+static int dhcp_route_configure(Route *route, Link *link) {
+        Route *ret;
+        int r;
+
+        assert(route);
+        assert(link);
+
+        r = route_configure(route, link, dhcp4_route_handler, &ret);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Failed to set DHCPv4 route: %m");
+
+        link->dhcp4_messages++;
+
+        r = set_ensure_put(&link->dhcp_routes, &route_hash_ops, ret);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Failed to store DHCPv4 route: %m");
+
+        (void) set_remove(link->dhcp_routes_old, ret);
+
+        return 0;
+}
+
+static int link_set_dns_routes(Link *link, const struct in_addr *address) {
+        const struct in_addr *dns;
+        uint32_t table;
+        int i, n, r;
+
+        assert(link);
+        assert(link->dhcp_lease);
+        assert(link->network);
+
+        if (!link->network->dhcp_use_dns ||
+            !link->network->dhcp_routes_to_dns)
+                return 0;
+
+        n = sd_dhcp_lease_get_dns(link->dhcp_lease, &dns);
+        if (IN_SET(n, 0, -ENODATA))
+                return 0;
+        if (n < 0)
+                return log_link_warning_errno(link, n, "DHCP error: could not get DNS servers: %m");
+
+        table = link_get_dhcp_route_table(link);
+
+        for (i = 0; i < n; i ++) {
+                _cleanup_(route_freep) Route *route = NULL;
+
+                r = route_new(&route);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Could not allocate route: %m");
+
+                /* Set routes to DNS servers. */
+
+                route->family = AF_INET;
+                route->dst.in = dns[i];
+                route->dst_prefixlen = 32;
+                route->prefsrc.in = *address;
+                route->scope = RT_SCOPE_LINK;
+                route->protocol = RTPROT_DHCP;
+                route->priority = link->network->dhcp_route_metric;
+                route->table = table;
+
+                r = dhcp_route_configure(route, link);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Could not set route to DNS server: %m");
+        }
+
+        return 0;
+}
+
+static int dhcp_prefix_route_from_lease(
+                const sd_dhcp_lease *lease,
+                uint32_t table,
+                const struct in_addr *address,
+                Route **ret_route) {
+
+        Route *route;
+        struct in_addr netmask;
+        int r;
+
+        r = sd_dhcp_lease_get_netmask((sd_dhcp_lease*) lease, &netmask);
+        if (r < 0)
+                return r;
+
+        r = route_new(&route);
+        if (r < 0)
+                return r;
+
+        route->family = AF_INET;
+        route->dst.in.s_addr = address->s_addr & netmask.s_addr;
+        route->dst_prefixlen = in4_addr_netmask_to_prefixlen(&netmask);
+        route->prefsrc.in = *address;
+        route->scope = RT_SCOPE_LINK;
+        route->protocol = RTPROT_DHCP;
+        route->table = table;
+        *ret_route = route;
+        return 0;
+}
+
+static int link_set_dhcp_routes(Link *link) {
+        _cleanup_free_ sd_dhcp_route **static_routes = NULL;
+        bool classless_route = false, static_route = false;
+        struct in_addr address;
+        uint32_t table;
+        Route *rt;
+        int r, n;
+
+        assert(link);
+
+        if (!link->dhcp_lease) /* link went down while we configured the IP addresses? */
+                return 0;
+
+        if (!link->network) /* link went down while we configured the IP addresses? */
+                return 0;
+
+        if (!link_has_carrier(link) && !link->network->configure_without_carrier)
+                /* During configuring addresses, the link lost its carrier. As networkd is dropping
+                 * the addresses now, let's not configure the routes either. */
+                return 0;
+
+        while ((rt = set_steal_first(link->dhcp_routes))) {
+                r = set_ensure_put(&link->dhcp_routes_old, &route_hash_ops, rt);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Failed to store old DHCPv4 route: %m");
+        }
+
+        table = link_get_dhcp_route_table(link);
+
+        r = sd_dhcp_lease_get_address(link->dhcp_lease, &address);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "DHCP error: could not get address: %m");
+
+        if (!link_prefixroute(link)) {
+                _cleanup_(route_freep) Route *prefix_route = NULL;
+
+                r = dhcp_prefix_route_from_lease(link->dhcp_lease, table, &address, &prefix_route);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Could not create prefix route: %m");
+
+                r = dhcp_route_configure(prefix_route, link);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Could not set prefix route: %m");
+        }
+
+        n = sd_dhcp_lease_get_routes(link->dhcp_lease, &static_routes);
+        if (n == -ENODATA)
+                log_link_debug_errno(link, n, "DHCP: No routes received from DHCP server: %m");
+        else if (n < 0)
+                return log_link_error_errno(link, n, "DHCP: could not get routes: %m");
+
+        for (int i = 0; i < n; i++) {
+                switch (sd_dhcp_route_get_option(static_routes[i])) {
+                case SD_DHCP_OPTION_CLASSLESS_STATIC_ROUTE:
+                        classless_route = true;
+                        break;
+                case SD_DHCP_OPTION_STATIC_ROUTE:
+                        static_route = true;
+                        break;
+                }
+        }
+
+        if (link->network->dhcp_use_routes) {
+                /* if the DHCP server returns both a Classless Static Routes option and a Static Routes option,
+                 * the DHCP client MUST ignore the Static Routes option. */
+                if (classless_route && static_route)
+                        log_link_warning(link, "Classless static routes received from DHCP server: ignoring static-route option");
+
+                for (int i = 0; i < n; i++) {
+                        _cleanup_(route_freep) Route *route = NULL;
+
+                        if (classless_route &&
+                            sd_dhcp_route_get_option(static_routes[i]) != SD_DHCP_OPTION_CLASSLESS_STATIC_ROUTE)
+                                continue;
+
+                        r = route_new(&route);
+                        if (r < 0)
+                                return log_link_error_errno(link, r, "Could not allocate route: %m");
+
+                        route->family = AF_INET;
+                        route->protocol = RTPROT_DHCP;
+                        route->gw_family = AF_INET;
+                        assert_se(sd_dhcp_route_get_gateway(static_routes[i], &route->gw.in) >= 0);
+                        assert_se(sd_dhcp_route_get_destination(static_routes[i], &route->dst.in) >= 0);
+                        assert_se(sd_dhcp_route_get_destination_prefix_length(static_routes[i], &route->dst_prefixlen) >= 0);
+                        route->priority = link->network->dhcp_route_metric;
+                        route->table = table;
+                        route->mtu = link->network->dhcp_route_mtu;
+                        route->scope = route_scope_from_address(route, &address);
+                        if (IN_SET(route->scope, RT_SCOPE_LINK, RT_SCOPE_UNIVERSE))
+                                route->prefsrc.in = address;
+
+                        if (set_contains(link->dhcp_routes, route))
+                                continue;
+
+                        r = dhcp_route_configure(route, link);
+                        if (r < 0)
+                                return log_link_error_errno(link, r, "Could not set route: %m");
+                }
+        }
+
+        if (link->network->dhcp_use_gateway) {
+                const struct in_addr *router;
+
+                r = sd_dhcp_lease_get_router(link->dhcp_lease, &router);
+                if (IN_SET(r, 0, -ENODATA))
+                        log_link_info(link, "DHCP: No gateway received from DHCP server.");
+                else if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP error: could not get gateway: %m");
+                else if (in4_addr_is_null(&router[0]))
+                        log_link_info(link, "DHCP: Received gateway is null.");
+                else if (classless_route)
+                        /* According to RFC 3442: If the DHCP server returns both a Classless Static Routes option and
+                         * a Router option, the DHCP client MUST ignore the Router option. */
+                        log_link_warning(link, "Classless static routes received from DHCP server: ignoring router option");
+                else {
+                        _cleanup_(route_freep) Route *route = NULL, *route_gw = NULL;
+
+                        r = route_new(&route_gw);
+                        if (r < 0)
+                                return log_link_error_errno(link, r, "Could not allocate route: %m");
+
+                        /* The dhcp netmask may mask out the gateway. Add an explicit
+                         * route for the gw host so that we can route no matter the
+                         * netmask or existing kernel route tables. */
+                        route_gw->family = AF_INET;
+                        route_gw->dst.in = router[0];
+                        route_gw->dst_prefixlen = 32;
+                        route_gw->prefsrc.in = address;
+                        route_gw->scope = RT_SCOPE_LINK;
+                        route_gw->protocol = RTPROT_DHCP;
+                        route_gw->priority = link->network->dhcp_route_metric;
+                        route_gw->table = table;
+                        route_gw->mtu = link->network->dhcp_route_mtu;
+
+                        r = dhcp_route_configure(route_gw, link);
+                        if (r < 0)
+                                return log_link_error_errno(link, r, "Could not set host route: %m");
+
+                        r = route_new(&route);
+                        if (r < 0)
+                                return log_link_error_errno(link, r, "Could not allocate route: %m");
+
+                        route->family = AF_INET;
+                        route->gw_family = AF_INET;
+                        route->gw.in = router[0];
+                        route->prefsrc.in = address;
+                        route->protocol = RTPROT_DHCP;
+                        route->priority = link->network->dhcp_route_metric;
+                        route->table = table;
+                        route->mtu = link->network->dhcp_route_mtu;
+
+                        r = dhcp_route_configure(route, link);
+                        if (r < 0)
+                                return log_link_error_errno(link, r, "Could not set router: %m");
+
+                        HASHMAP_FOREACH(rt, link->network->routes_by_section) {
+                                if (!rt->gateway_from_dhcp_or_ra)
+                                        continue;
+
+                                if (rt->gw_family != AF_INET)
+                                        continue;
+
+                                rt->gw.in = router[0];
+                                if (!rt->protocol_set)
+                                        rt->protocol = RTPROT_DHCP;
+                                if (!rt->priority_set)
+                                        rt->priority = link->network->dhcp_route_metric;
+                                if (!rt->table_set)
+                                        rt->table = table;
+                                if (rt->mtu == 0)
+                                        rt->mtu = link->network->dhcp_route_mtu;
+
+                                r = dhcp_route_configure(rt, link);
+                                if (r < 0)
+                                        return log_link_error_errno(link, r, "Could not set gateway: %m");
+                        }
+                }
+        }
+
+        return link_set_dns_routes(link, &address);
+}
+
+static int dhcp_reset_mtu(Link *link) {
+        uint16_t mtu;
+        int r;
+
+        assert(link);
+
+        if (!link->network->dhcp_use_mtu)
+                return 0;
+
+        r = sd_dhcp_lease_get_mtu(link->dhcp_lease, &mtu);
+        if (r == -ENODATA)
+                return 0;
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP error: failed to get MTU from lease: %m");
+
+        if (link->original_mtu == mtu)
+                return 0;
+
+        r = link_set_mtu(link, link->original_mtu);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP error: could not reset MTU: %m");
+
+        return 0;
+}
+
+static int dhcp_reset_hostname(Link *link) {
+        const char *hostname;
+        int r;
+
+        assert(link);
+
+        if (!link->network->dhcp_use_hostname)
+                return 0;
+
+        hostname = link->network->dhcp_hostname;
+        if (!hostname)
+                (void) sd_dhcp_lease_get_hostname(link->dhcp_lease, &hostname);
+
+        if (!hostname)
+                return 0;
+
+        /* If a hostname was set due to the lease, then unset it now. */
+        r = manager_set_hostname(link->manager, NULL);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP error: Failed to reset transient hostname: %m");
+
+        return 0;
+}
+
+static int dhcp4_remove_route_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
+        int r;
+
+        assert(m);
+        assert(link);
+        assert(link->dhcp4_remove_messages > 0);
+
+        link->dhcp4_remove_messages--;
+
+        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
+                return 1;
+
+        r = sd_netlink_message_get_errno(m);
+        if (r < 0 && r != -ESRCH)
+                log_link_message_warning_errno(link, m, r, "Failed to remove DHCPv4 route, ignoring");
+
+        if (link->dhcp4_remove_messages == 0) {
+                r = dhcp4_update_address(link, false);
+                if (r < 0)
+                        link_enter_failed(link);
+        }
+
+        return 1;
+}
+
+static int dhcp4_remove_address_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
+        int r;
+
+        assert(m);
+        assert(link);
+        assert(link->dhcp4_remove_messages > 0);
+
+        link->dhcp4_remove_messages--;
+
+        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
+                return 1;
+
+        r = sd_netlink_message_get_errno(m);
+        if (r < 0 && r != -EADDRNOTAVAIL)
+                log_link_message_warning_errno(link, m, r, "Failed to remove DHCPv4 address, ignoring");
+        else
+                (void) manager_rtnl_process_address(rtnl, m, link->manager);
+
+        if (link->dhcp4_remove_messages == 0) {
+                r = dhcp4_update_address(link, false);
+                if (r < 0)
+                        link_enter_failed(link);
+        }
+
+        return 1;
+}
+
+static int dhcp4_remove_all(Link *link) {
+        Route *route;
+        int k, r = 0;
+
+        assert(link);
+
+        SET_FOREACH(route, link->dhcp_routes) {
+                k = route_remove(route, NULL, link, dhcp4_remove_route_handler);
+                if (k < 0)
+                        r = k;
+                else
+                        link->dhcp4_remove_messages++;
+        }
+
+        if (link->dhcp_address) {
+                k = address_remove(link->dhcp_address, link, dhcp4_remove_address_handler);
+                if (k < 0)
+                        r = k;
+                else
+                        link->dhcp4_remove_messages++;
+        }
+
+        return r;
+}
+
+static int dhcp_lease_lost(Link *link) {
+        int k, r = 0;
+
+        assert(link);
+        assert(link->dhcp_lease);
+
+        log_link_info(link, "DHCP lease lost");
+
+        link->dhcp4_configured = false;
+
+        /* dhcp_lease_lost() may be called during renewing IP address. */
+        k = dhcp4_release_old_lease(link);
+        if (k < 0)
+                r = k;
+
+        k = dhcp4_remove_all(link);
+        if (k < 0)
+                r = k;
+
+        k = dhcp_reset_mtu(link);
+        if (k < 0)
+                r = k;
+
+        k = dhcp_reset_hostname(link);
+        if (k < 0)
+                r = k;
+
+        link->dhcp_lease = sd_dhcp_lease_unref(link->dhcp_lease);
+        link_dirty(link);
+
+        (void) sd_ipv4acd_stop(link->dhcp_acd);
+
+        return r;
+}
+
+static void dhcp_address_on_acd(sd_ipv4acd *acd, int event, void *userdata) {
+        _cleanup_free_ char *pretty = NULL;
+        union in_addr_union address = {};
+        Link *link;
+        int r;
+
+        assert(acd);
+        assert(userdata);
+
+        link = userdata;
+
+        switch (event) {
+        case SD_IPV4ACD_EVENT_STOP:
+                log_link_debug(link, "Stopping ACD client for DHCP4...");
+                return;
+
+        case SD_IPV4ACD_EVENT_BIND:
+                if (DEBUG_LOGGING) {
+                        (void) sd_dhcp_lease_get_address(link->dhcp_lease, &address.in);
+                        (void) in_addr_to_string(AF_INET, &address, &pretty);
+                        log_link_debug(link, "Successfully claimed DHCP4 address %s", strna(pretty));
+                }
+                link->dhcp4_address_bind = true;
+                dhcp4_check_ready(link);
+                break;
+
+        case SD_IPV4ACD_EVENT_CONFLICT:
+                (void) sd_dhcp_lease_get_address(link->dhcp_lease, &address.in);
+                (void) in_addr_to_string(AF_INET, &address, &pretty);
+                log_link_warning(link, "DAD conflict. Dropping DHCP4 address %s", strna(pretty));
+
+                r = sd_dhcp_client_send_decline(link->dhcp_client);
+                if (r < 0)
+                        log_link_warning_errno(link, r, "Failed to send DHCP DECLINE, ignoring: %m");
+
+                if (link->dhcp_lease) {
+                        r = dhcp_lease_lost(link);
+                        if (r < 0)
+                                link_enter_failed(link);
+                }
+                break;
+
+        default:
+                assert_not_reached("Invalid IPv4ACD event.");
+        }
+
+        (void) sd_ipv4acd_stop(acd);
+
+        return;
+}
+
+static int dhcp4_configure_dad(Link *link) {
+        int r;
+
+        assert(link);
+        assert(link->manager);
+        assert(link->network);
+
+        if (!link->network->dhcp_send_decline)
+                return 0;
+
+        if (!link->dhcp_acd) {
+                r = sd_ipv4acd_new(&link->dhcp_acd);
+                if (r < 0)
+                        return r;
+
+                r = sd_ipv4acd_attach_event(link->dhcp_acd, link->manager->event, 0);
+                if (r < 0)
+                        return r;
+        }
+
+        r = sd_ipv4acd_set_ifindex(link->dhcp_acd, link->ifindex);
+        if (r < 0)
+                return r;
+
+        r = sd_ipv4acd_set_mac(link->dhcp_acd, &link->hw_addr.addr.ether);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+static int dhcp4_dad_update_mac(Link *link) {
+        bool running;
+        int r;
+
+        assert(link);
+
+        if (!link->dhcp_acd)
+                return 0;
+
+        running = sd_ipv4acd_is_running(link->dhcp_acd);
+
+        r = sd_ipv4acd_stop(link->dhcp_acd);
+        if (r < 0)
+                return r;
+
+        r = sd_ipv4acd_set_mac(link->dhcp_acd, &link->hw_addr.addr.ether);
+        if (r < 0)
+                return r;
+
+        if (running) {
+                r = sd_ipv4acd_start(link->dhcp_acd, true);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int dhcp4_start_acd(Link *link) {
+        union in_addr_union addr;
+        struct in_addr old;
+        int r;
+
+        if (!link->network->dhcp_send_decline)
+                return 0;
+
+        if (!link->dhcp_lease)
+                return 0;
+
+        (void) sd_ipv4acd_stop(link->dhcp_acd);
+
+        link->dhcp4_address_bind = false;
+
+        r = sd_dhcp_lease_get_address(link->dhcp_lease, &addr.in);
+        if (r < 0)
+                return r;
+
+        r = sd_ipv4acd_get_address(link->dhcp_acd, &old);
+        if (r < 0)
+                return r;
+
+        r = sd_ipv4acd_set_address(link->dhcp_acd, &addr.in);
+        if (r < 0)
+                return r;
+
+        r = sd_ipv4acd_set_callback(link->dhcp_acd, dhcp_address_on_acd, link);
+        if (r < 0)
+                return r;
+
+        if (DEBUG_LOGGING) {
+                _cleanup_free_ char *pretty = NULL;
+
+                (void) in_addr_to_string(AF_INET, &addr, &pretty);
+                log_link_debug(link, "Starting IPv4ACD client. Probing DHCPv4 address %s", strna(pretty));
+        }
+
+        r = sd_ipv4acd_start(link->dhcp_acd, !in4_addr_equal(&addr.in, &old));
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+static int dhcp4_address_ready_callback(Address *address) {
+        Link *link;
+        int r;
+
+        assert(address);
+
+        link = address->link;
+
+        /* Do not call this again. */
+        address->callback = NULL;
+
+        r = link_set_dhcp_routes(link);
+        if (r < 0)
+                return r;
+
+        /* Reconfigure static routes as kernel may remove some routes when lease expires. */
+        r = link_set_routes(link);
+        if (r < 0)
+                return r;
+
+        r = dhcp4_start_acd(link);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Failed to start IPv4ACD for DHCP4 address: %m");
+
+        dhcp4_check_ready(link);
+        return 0;
+}
+
+static int dhcp4_address_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
+        int r;
+
+        assert(link);
+
+        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
+                return 1;
+
+        r = sd_netlink_message_get_errno(m);
+        if (r < 0 && r != -EEXIST) {
+                log_link_message_warning_errno(link, m, r, "Could not set DHCPv4 address");
+                link_enter_failed(link);
+                return 1;
+        } else if (r >= 0)
+                (void) manager_rtnl_process_address(rtnl, m, link->manager);
+
+        if (address_is_ready(link->dhcp_address)) {
+                r = dhcp4_address_ready_callback(link->dhcp_address);
+                if (r < 0) {
+                        link_enter_failed(link);
+                        return 1;
+                }
+        } else
+                link->dhcp_address->callback = dhcp4_address_ready_callback;
+
+        return 1;
+}
+
+static int dhcp4_update_address(Link *link, bool announce) {
+        _cleanup_(address_freep) Address *addr = NULL;
+        uint32_t lifetime = CACHE_INFO_INFINITY_LIFE_TIME;
+        struct in_addr address, netmask;
+        unsigned prefixlen;
+        Address *ret;
+        int r;
+
+        assert(link);
+        assert(link->network);
+
+        if (!link->dhcp_lease)
+                return 0;
+
+        link_set_state(link, LINK_STATE_CONFIGURING);
+        link->dhcp4_configured = false;
+
+        /* address_handler calls link_set_routes() and link_set_nexthop(). Before they are called, the
+         * related flags must be cleared. Otherwise, the link becomes configured state before routes
+         * are configured. */
+        link->static_routes_configured = false;
+        link->static_nexthops_configured = false;
+
+        r = sd_dhcp_lease_get_address(link->dhcp_lease, &address);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "DHCP error: no address: %m");
+
+        r = sd_dhcp_lease_get_netmask(link->dhcp_lease, &netmask);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "DHCP error: no netmask: %m");
+
+        if (!FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP)) {
+                r = sd_dhcp_lease_get_lifetime(link->dhcp_lease, &lifetime);
+                if (r < 0)
+                        return log_link_warning_errno(link, r, "DHCP error: no lifetime: %m");
+        }
+
+        prefixlen = in4_addr_netmask_to_prefixlen(&netmask);
+
+        if (announce) {
+                const struct in_addr *router;
+
+                r = sd_dhcp_lease_get_router(link->dhcp_lease, &router);
+                if (r < 0 && r != -ENODATA)
+                        return log_link_error_errno(link, r, "DHCP error: Could not get gateway: %m");
+
+                if (r > 0 && !in4_addr_is_null(&router[0]))
+                        log_struct(LOG_INFO,
+                                   LOG_LINK_INTERFACE(link),
+                                   LOG_LINK_MESSAGE(link, "DHCPv4 address "IPV4_ADDRESS_FMT_STR"/%u via "IPV4_ADDRESS_FMT_STR,
+                                                    IPV4_ADDRESS_FMT_VAL(address),
+                                                    prefixlen,
+                                                    IPV4_ADDRESS_FMT_VAL(router[0])),
+                                   "ADDRESS="IPV4_ADDRESS_FMT_STR, IPV4_ADDRESS_FMT_VAL(address),
+                                   "PREFIXLEN=%u", prefixlen,
+                                   "GATEWAY="IPV4_ADDRESS_FMT_STR, IPV4_ADDRESS_FMT_VAL(router[0]));
+                else
+                        log_struct(LOG_INFO,
+                                   LOG_LINK_INTERFACE(link),
+                                   LOG_LINK_MESSAGE(link, "DHCPv4 address "IPV4_ADDRESS_FMT_STR"/%u",
+                                                    IPV4_ADDRESS_FMT_VAL(address),
+                                                    prefixlen),
+                                   "ADDRESS="IPV4_ADDRESS_FMT_STR, IPV4_ADDRESS_FMT_VAL(address),
+                                   "PREFIXLEN=%u", prefixlen);
+        }
+
+        r = address_new(&addr);
+        if (r < 0)
+                return log_oom();
+
+        addr->family = AF_INET;
+        addr->in_addr.in.s_addr = address.s_addr;
+        addr->cinfo.ifa_prefered = lifetime;
+        addr->cinfo.ifa_valid = lifetime;
+        addr->prefixlen = prefixlen;
+        if (prefixlen <= 30)
+                addr->broadcast.s_addr = address.s_addr | ~netmask.s_addr;
+        SET_FLAG(addr->flags, IFA_F_NOPREFIXROUTE, !link_prefixroute(link));
+
+        /* allow reusing an existing address and simply update its lifetime
+         * in case it already exists */
+        r = address_configure(addr, link, dhcp4_address_handler, true, &ret);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Failed to set DHCPv4 address: %m");
+
+        if (!address_equal(link->dhcp_address, ret))
+                link->dhcp_address_old = link->dhcp_address;
+        link->dhcp_address = ret;
+
+        return 0;
+}
+
+static int dhcp_lease_renew(sd_dhcp_client *client, Link *link) {
+        sd_dhcp_lease *lease;
+        int r;
+
+        assert(link);
+        assert(client);
+
+        r = sd_dhcp_client_get_lease(client, &lease);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "DHCP error: no lease: %m");
+
+        sd_dhcp_lease_unref(link->dhcp_lease);
+        link->dhcp_lease = sd_dhcp_lease_ref(lease);
+        link_dirty(link);
+
+        return dhcp4_update_address(link, false);
+}
+
+static int dhcp_lease_acquired(sd_dhcp_client *client, Link *link) {
+        sd_dhcp_lease *lease;
+        int r;
+
+        assert(client);
+        assert(link);
+
+        r = sd_dhcp_client_get_lease(client, &lease);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP error: No lease: %m");
+
+        sd_dhcp_lease_unref(link->dhcp_lease);
+        link->dhcp_lease = sd_dhcp_lease_ref(lease);
+        link_dirty(link);
+
+        if (link->network->dhcp_use_mtu) {
+                uint16_t mtu;
+
+                r = sd_dhcp_lease_get_mtu(lease, &mtu);
+                if (r >= 0) {
+                        r = link_set_mtu(link, mtu);
+                        if (r < 0)
+                                log_link_error_errno(link, r, "Failed to set MTU to %" PRIu16 ": %m", mtu);
+                }
+        }
+
+        if (link->network->dhcp_use_hostname) {
+                const char *dhcpname = NULL;
+                _cleanup_free_ char *hostname = NULL;
+
+                if (link->network->dhcp_hostname)
+                        dhcpname = link->network->dhcp_hostname;
+                else
+                        (void) sd_dhcp_lease_get_hostname(lease, &dhcpname);
+
+                if (dhcpname) {
+                        r = shorten_overlong(dhcpname, &hostname);
+                        if (r < 0)
+                                log_link_warning_errno(link, r, "Unable to shorten overlong DHCP hostname '%s', ignoring: %m", dhcpname);
+                        if (r == 1)
+                                log_link_notice(link, "Overlong DHCP hostname received, shortened from '%s' to '%s'", dhcpname, hostname);
+                }
+
+                if (hostname) {
+                        r = manager_set_hostname(link->manager, hostname);
+                        if (r < 0)
+                                log_link_error_errno(link, r, "Failed to set transient hostname to '%s': %m", hostname);
+                }
+        }
+
+        if (link->network->dhcp_use_timezone) {
+                const char *tz = NULL;
+
+                (void) sd_dhcp_lease_get_timezone(link->dhcp_lease, &tz);
+
+                if (tz) {
+                        r = manager_set_timezone(link->manager, tz);
+                        if (r < 0)
+                                log_link_error_errno(link, r, "Failed to set timezone to '%s': %m", tz);
+                }
+        }
+
+        if (link->dhcp4_remove_messages == 0) {
+                r = dhcp4_update_address(link, true);
+                if (r < 0)
+                        return r;
+        } else
+                log_link_debug(link,
+                               "The link has previously assigned DHCPv4 address or routes. "
+                               "The newly assigned address and routes will set up after old ones are removed.");
+
+        return 0;
+}
+
+static int dhcp_lease_ip_change(sd_dhcp_client *client, Link *link) {
+        int r;
+
+        r = dhcp_lease_acquired(client, link);
+        if (r < 0)
+                (void) dhcp_lease_lost(link);
+
+        return r;
+}
+
+static int dhcp_server_is_deny_listed(Link *link, sd_dhcp_client *client) {
+        sd_dhcp_lease *lease;
+        struct in_addr addr;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(client);
+
+        r = sd_dhcp_client_get_lease(client, &lease);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Failed to get DHCP lease: %m");
+
+        r = sd_dhcp_lease_get_server_identifier(lease, &addr);
+        if (r < 0)
+                return log_link_debug_errno(link, r, "Failed to get DHCP server IP address: %m");
+
+        if (set_contains(link->network->dhcp_deny_listed_ip, UINT32_TO_PTR(addr.s_addr))) {
+                log_struct(LOG_DEBUG,
+                           LOG_LINK_INTERFACE(link),
+                           LOG_LINK_MESSAGE(link, "DHCPv4 server IP address "IPV4_ADDRESS_FMT_STR" found in deny-list, ignoring offer",
+                                            IPV4_ADDRESS_FMT_VAL(addr)));
+                return true;
+        }
+
+        return false;
+}
+
+static int dhcp_server_is_allow_listed(Link *link, sd_dhcp_client *client) {
+        sd_dhcp_lease *lease;
+        struct in_addr addr;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(client);
+
+        r = sd_dhcp_client_get_lease(client, &lease);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Failed to get DHCP lease: %m");
+
+        r = sd_dhcp_lease_get_server_identifier(lease, &addr);
+        if (r < 0)
+                return log_link_debug_errno(link, r, "Failed to get DHCP server IP address: %m");
+
+        if (set_contains(link->network->dhcp_allow_listed_ip, UINT32_TO_PTR(addr.s_addr))) {
+                log_struct(LOG_DEBUG,
+                           LOG_LINK_INTERFACE(link),
+                           LOG_LINK_MESSAGE(link, "DHCPv4 server IP address "IPV4_ADDRESS_FMT_STR" found in allow-list, accepting offer",
+                                            IPV4_ADDRESS_FMT_VAL(addr)));
+                return true;
+        }
+
+        return false;
+}
+
+static int dhcp4_handler(sd_dhcp_client *client, int event, void *userdata) {
+        Link *link = userdata;
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(link->manager);
+
+        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
+                return 0;
+
+        switch (event) {
+                case SD_DHCP_CLIENT_EVENT_STOP:
+
+                        if (link_ipv4ll_enabled(link, ADDRESS_FAMILY_FALLBACK_IPV4)) {
+                                assert(link->ipv4ll);
+
+                                log_link_debug(link, "DHCP client is stopped. Acquiring IPv4 link-local address");
+
+                                r = sd_ipv4ll_start(link->ipv4ll);
+                                if (r < 0)
+                                        return log_link_warning_errno(link, r, "Could not acquire IPv4 link-local address: %m");
+                        }
+
+                        if (FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP)) {
+                                log_link_notice(link, "DHCPv4 connection considered critical, ignoring request to reconfigure it.");
+                                return 0;
+                        }
+
+                        if (link->dhcp_lease) {
+                                if (link->network->dhcp_send_release) {
+                                        r = sd_dhcp_client_send_release(client);
+                                        if (r < 0)
+                                                log_link_warning_errno(link, r, "Failed to send DHCP RELEASE, ignoring: %m");
+                                }
+
+                                r = dhcp_lease_lost(link);
+                                if (r < 0) {
+                                        link_enter_failed(link);
+                                        return r;
+                                }
+                        }
+
+                        break;
+                case SD_DHCP_CLIENT_EVENT_EXPIRED:
+                        if (FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP)) {
+                                log_link_notice(link, "DHCPv4 connection considered critical, ignoring request to reconfigure it.");
+                                return 0;
+                        }
+
+                        if (link->dhcp_lease) {
+                                r = dhcp_lease_lost(link);
+                                if (r < 0) {
+                                        link_enter_failed(link);
+                                        return r;
+                                }
+                        }
+
+                        break;
+                case SD_DHCP_CLIENT_EVENT_IP_CHANGE:
+                        if (FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP)) {
+                                log_link_notice(link, "DHCPv4 connection considered critical, ignoring request to reconfigure it.");
+                                return 0;
+                        }
+
+                        r = dhcp_lease_ip_change(client, link);
+                        if (r < 0) {
+                                link_enter_failed(link);
+                                return r;
+                        }
+
+                        break;
+                case SD_DHCP_CLIENT_EVENT_RENEW:
+                        r = dhcp_lease_renew(client, link);
+                        if (r < 0) {
+                                link_enter_failed(link);
+                                return r;
+                        }
+                        break;
+                case SD_DHCP_CLIENT_EVENT_IP_ACQUIRE:
+                        r = dhcp_lease_acquired(client, link);
+                        if (r < 0) {
+                                link_enter_failed(link);
+                                return r;
+                        }
+                        break;
+                case SD_DHCP_CLIENT_EVENT_SELECTING:
+                        if (!set_isempty(link->network->dhcp_allow_listed_ip)) {
+                                r = dhcp_server_is_allow_listed(link, client);
+                                if (r < 0)
+                                        return r;
+                                if (r == 0)
+                                        return -ENOMSG;
+                        } else {
+                                r = dhcp_server_is_deny_listed(link, client);
+                                if (r < 0)
+                                        return r;
+                                if (r != 0)
+                                        return -ENOMSG;
+                        }
+                        break;
+                default:
+                        if (event < 0)
+                                log_link_warning_errno(link, event, "DHCP error: Client failed: %m");
+                        else
+                                log_link_warning(link, "DHCP unknown event: %i", event);
+                        break;
+        }
+
+        return 0;
+}
+
+static int dhcp4_set_hostname(Link *link) {
+        _cleanup_free_ char *hostname = NULL;
+        const char *hn;
+        int r;
+
+        assert(link);
+
+        if (!link->network->dhcp_send_hostname)
+                hn = NULL;
+        else if (link->network->dhcp_hostname)
+                hn = link->network->dhcp_hostname;
+        else {
+                r = gethostname_strict(&hostname);
+                if (r < 0 && r != -ENXIO) /* ENXIO: no hostname set or hostname is "localhost" */
+                        return r;
+
+                hn = hostname;
+        }
+
+        r = sd_dhcp_client_set_hostname(link->dhcp_client, hn);
+        if (r == -EINVAL && hostname)
+                /* Ignore error when the machine's hostname is not suitable to send in DHCP packet. */
+                log_link_warning_errno(link, r, "DHCP4 CLIENT: Failed to set hostname from kernel hostname, ignoring: %m");
+        else if (r < 0)
+                return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set hostname: %m");
+
+        return 0;
+}
+
+static bool promote_secondaries_enabled(const char *ifname) {
+        _cleanup_free_ char *promote_secondaries_sysctl = NULL;
+        char *promote_secondaries_path;
+        int r;
+
+        promote_secondaries_path = strjoina("net/ipv4/conf/", ifname, "/promote_secondaries");
+        r = sysctl_read(promote_secondaries_path, &promote_secondaries_sysctl);
+        if (r < 0) {
+                log_debug_errno(r, "Cannot read sysctl %s", promote_secondaries_path);
+                return false;
+        }
+
+        truncate_nl(promote_secondaries_sysctl);
+        r = parse_boolean(promote_secondaries_sysctl);
+        if (r < 0)
+                log_warning_errno(r, "Cannot parse sysctl %s with content %s as boolean", promote_secondaries_path, promote_secondaries_sysctl);
+        return r > 0;
+}
+
+/* dhcp4_set_promote_secondaries will ensure this interface has
+ * the "promote_secondaries" option in the kernel set. If this sysctl
+ * is not set DHCP will work only as long as the IP address does not
+ * changes between leases. The kernel will remove all secondary IP
+ * addresses of an interface otherwise. The way systemd-network works
+ * is that the new IP of a lease is added as a secondary IP and when
+ * the primary one expires it relies on the kernel to promote the
+ * secondary IP. See also https://github.com/systemd/systemd/issues/7163
+ */
+static int dhcp4_set_promote_secondaries(Link *link) {
+        int r;
+
+        assert(link);
+
+        /* check if the kernel has promote_secondaries enabled for our
+         * interface. If it is not globally enabled or enabled for the
+         * specific interface we must either enable it.
+         */
+        if (!(promote_secondaries_enabled("all") || promote_secondaries_enabled(link->ifname))) {
+                char *promote_secondaries_path = NULL;
+
+                log_link_debug(link, "promote_secondaries is unset, setting it");
+                promote_secondaries_path = strjoina("net/ipv4/conf/", link->ifname, "/promote_secondaries");
+                r = sysctl_write(promote_secondaries_path, "1");
+                if (r < 0)
+                        log_link_warning_errno(link, r, "cannot set sysctl %s to 1", promote_secondaries_path);
+                return r > 0;
+        }
+
+        return 0;
+}
+
+static int dhcp4_set_client_identifier(Link *link) {
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(link->dhcp_client);
+
+        switch (link->network->dhcp_client_identifier) {
+        case DHCP_CLIENT_ID_DUID: {
+                /* If configured, apply user specified DUID and IAID */
+                const DUID *duid = link_get_duid(link);
+
+                if (duid->type == DUID_TYPE_LLT && duid->raw_data_len == 0)
+                        r = sd_dhcp_client_set_iaid_duid_llt(link->dhcp_client,
+                                                             link->network->iaid_set,
+                                                             link->network->iaid,
+                                                             duid->llt_time);
+                else
+                        r = sd_dhcp_client_set_iaid_duid(link->dhcp_client,
+                                                         link->network->iaid_set,
+                                                         link->network->iaid,
+                                                         duid->type,
+                                                         duid->raw_data_len > 0 ? duid->raw_data : NULL,
+                                                         duid->raw_data_len);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set IAID+DUID: %m");
+                break;
+        }
+        case DHCP_CLIENT_ID_DUID_ONLY: {
+                /* If configured, apply user specified DUID */
+                const DUID *duid = link_get_duid(link);
+
+                if (duid->type == DUID_TYPE_LLT && duid->raw_data_len == 0)
+                        r = sd_dhcp_client_set_duid_llt(link->dhcp_client,
+                                                        duid->llt_time);
+                else
+                        r = sd_dhcp_client_set_duid(link->dhcp_client,
+                                                    duid->type,
+                                                    duid->raw_data_len > 0 ? duid->raw_data : NULL,
+                                                    duid->raw_data_len);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set DUID: %m");
+                break;
+        }
+        case DHCP_CLIENT_ID_MAC: {
+                const uint8_t *hw_addr = link->hw_addr.addr.bytes;
+                size_t hw_addr_len = link->hw_addr.length;
+
+                if (link->iftype == ARPHRD_INFINIBAND && hw_addr_len == INFINIBAND_ALEN) {
+                        /* set_client_id expects only last 8 bytes of an IB address */
+                        hw_addr += INFINIBAND_ALEN - 8;
+                        hw_addr_len -= INFINIBAND_ALEN - 8;
+                }
+
+                r = sd_dhcp_client_set_client_id(link->dhcp_client,
+                                                 link->iftype,
+                                                 hw_addr,
+                                                 hw_addr_len);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set client ID: %m");
+                break;
+        }
+        default:
+                assert_not_reached("Unknown client identifier type.");
+        }
+
+        return 0;
+}
+
+static int dhcp4_init(Link *link) {
+        int r;
+
+        assert(link);
+
+        if (link->dhcp_client)
+                return 0;
+
+        r = sd_dhcp_client_new(&link->dhcp_client, link->network->dhcp_anonymize);
+        if (r < 0)
+                return r;
+
+        r = sd_dhcp_client_attach_event(link->dhcp_client, link->manager->event, 0);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+int dhcp4_configure(Link *link) {
+        sd_dhcp_option *send_option;
+        void *request_options;
+        int r;
+
+        assert(link);
+        assert(link->network);
+
+        if (!link_dhcp4_enabled(link))
+                return 0;
+
+        r = dhcp4_set_promote_secondaries(link);
+        if (r < 0)
+                return r;
+
+        r = dhcp4_init(link);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to initialize DHCP4 client: %m");
+
+        r = sd_dhcp_client_set_mac(link->dhcp_client,
+                                   link->hw_addr.addr.bytes,
+                                   link->bcast_addr.length > 0 ? link->bcast_addr.addr.bytes : NULL,
+                                   link->hw_addr.length, link->iftype);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MAC address: %m");
+
+        r = sd_dhcp_client_set_ifindex(link->dhcp_client, link->ifindex);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set ifindex: %m");
+
+        r = sd_dhcp_client_set_callback(link->dhcp_client, dhcp4_handler, link);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set callback: %m");
+
+        r = sd_dhcp_client_set_request_broadcast(link->dhcp_client,
+                                                 link->network->dhcp_broadcast);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for broadcast: %m");
+
+        if (link->mtu) {
+                r = sd_dhcp_client_set_mtu(link->dhcp_client, link->mtu);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MTU: %m");
+        }
+
+        if (link->network->dhcp_use_mtu) {
+                r = sd_dhcp_client_set_request_option(link->dhcp_client,
+                                                      SD_DHCP_OPTION_INTERFACE_MTU);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for MTU: %m");
+        }
+
+        /* NOTE: even if this variable is called "use", it also "sends" PRL
+         * options, maybe there should be a different configuration variable
+         * to send or not route options?. */
+        /* NOTE: when using Anonymize=yes, routes PRL options are sent
+         * by default, so they don't need to be added here. */
+        if (link->network->dhcp_use_routes && !link->network->dhcp_anonymize) {
+                r = sd_dhcp_client_set_request_option(link->dhcp_client,
+                                                      SD_DHCP_OPTION_STATIC_ROUTE);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for static route: %m");
+
+                r = sd_dhcp_client_set_request_option(link->dhcp_client,
+                                                      SD_DHCP_OPTION_CLASSLESS_STATIC_ROUTE);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for classless static route: %m");
+        }
+
+        if (link->network->dhcp_use_domains != DHCP_USE_DOMAINS_NO && !link->network->dhcp_anonymize) {
+                r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_DOMAIN_SEARCH_LIST);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for domain search list: %m");
+        }
+
+        if (link->network->dhcp_use_ntp) {
+                r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_NTP_SERVER);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for NTP server: %m");
+        }
+
+        if (link->network->dhcp_use_sip) {
+                r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_SIP_SERVER);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for SIP server: %m");
+        }
+
+        if (link->network->dhcp_use_timezone) {
+                r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_NEW_TZDB_TIMEZONE);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for timezone: %m");
+        }
+
+        SET_FOREACH(request_options, link->network->dhcp_request_options) {
+                uint32_t option = PTR_TO_UINT32(request_options);
+
+                r = sd_dhcp_client_set_request_option(link->dhcp_client, option);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for '%u': %m", option);
+        }
+
+        ORDERED_HASHMAP_FOREACH(send_option, link->network->dhcp_client_send_options) {
+                r = sd_dhcp_client_add_option(link->dhcp_client, send_option);
+                if (r == -EEXIST)
+                        continue;
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set send option: %m");
+        }
+
+        ORDERED_HASHMAP_FOREACH(send_option, link->network->dhcp_client_send_vendor_options) {
+                r = sd_dhcp_client_add_vendor_option(link->dhcp_client, send_option);
+                if (r == -EEXIST)
+                        continue;
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set send option: %m");
+        }
+
+        r = dhcp4_set_hostname(link);
+        if (r < 0)
+                return r;
+
+        if (link->network->dhcp_vendor_class_identifier) {
+                r = sd_dhcp_client_set_vendor_class_identifier(link->dhcp_client,
+                                                               link->network->dhcp_vendor_class_identifier);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set vendor class identifier: %m");
+        }
+
+       if (link->network->dhcp_mudurl) {
+                r = sd_dhcp_client_set_mud_url(link->dhcp_client,
+                                               link->network->dhcp_mudurl);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MUD URL: %m");
+        }
+
+        if (link->network->dhcp_user_class) {
+                r = sd_dhcp_client_set_user_class(link->dhcp_client, link->network->dhcp_user_class);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set user class: %m");
+        }
+
+        if (link->network->dhcp_client_port) {
+                r = sd_dhcp_client_set_client_port(link->dhcp_client, link->network->dhcp_client_port);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set listen port: %m");
+        }
+
+        if (link->network->dhcp_max_attempts > 0) {
+                r = sd_dhcp_client_set_max_attempts(link->dhcp_client, link->network->dhcp_max_attempts);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set max attempts: %m");
+        }
+
+        if (link->network->dhcp_ip_service_type > 0) {
+                r = sd_dhcp_client_set_service_type(link->dhcp_client, link->network->dhcp_ip_service_type);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set IP service type: %m");
+        }
+
+        if (link->network->dhcp_fallback_lease_lifetime > 0) {
+                r = sd_dhcp_client_set_fallback_lease_lifetime(link->dhcp_client, link->network->dhcp_fallback_lease_lifetime);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed set to lease lifetime: %m");
+        }
+
+        r = dhcp4_configure_dad(link);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to configure service type: %m");
+
+        return dhcp4_set_client_identifier(link);
+}
+
+int dhcp4_update_mac(Link *link) {
+        int r;
+
+        assert(link);
+
+        if (!link->dhcp_client)
+                return 0;
+
+        r = sd_dhcp_client_set_mac(link->dhcp_client, link->hw_addr.addr.bytes,
+                                   link->bcast_addr.length > 0 ? link->bcast_addr.addr.bytes : NULL,
+                                   link->hw_addr.length, link->iftype);
+        if (r < 0)
+                return r;
+
+        r = dhcp4_set_client_identifier(link);
+        if (r < 0)
+                return r;
+
+        r = dhcp4_dad_update_mac(link);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+int link_deserialize_dhcp4(Link *link, const char *dhcp4_address) {
+        union in_addr_union address;
+        int r;
+
+        assert(link);
+
+        if (isempty(dhcp4_address))
+                return 0;
+
+        r = in_addr_from_string(AF_INET, dhcp4_address, &address);
+        if (r < 0)
+                return log_link_debug_errno(link, r, "Failed to parse DHCPv4 address: %s", dhcp4_address);
+
+        r = dhcp4_init(link);
+        if (r < 0)
+                return log_link_debug_errno(link, r, "Failed to initialize DHCPv4 client: %m");
+
+        r = sd_dhcp_client_set_request_address(link->dhcp_client, &address.in);
+        if (r < 0)
+                return log_link_debug_errno(link, r, "Failed to set initial DHCPv4 address %s: %m", dhcp4_address);
+
+        return 0;
+}
+
+int config_parse_dhcp_max_attempts(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        Network *network = data;
+        uint64_t a;
+        int r;
+
+        assert(network);
+        assert(lvalue);
+        assert(rvalue);
+
+        if (isempty(rvalue)) {
+                network->dhcp_max_attempts = 0;
+                return 0;
+        }
+
+        if (streq(rvalue, "infinity")) {
+                network->dhcp_max_attempts = (uint64_t) -1;
+                return 0;
+        }
+
+        r = safe_atou64(rvalue, &a);
+        if (r < 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, r,
+                           "Failed to parse DHCP maximum attempts, ignoring: %s", rvalue);
+                return 0;
+        }
+
+        if (a == 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "%s= must be positive integer or 'infinity', ignoring: %s", lvalue, rvalue);
+                return 0;
+        }
+
+        network->dhcp_max_attempts = a;
+
+        return 0;
+}
+
+int config_parse_dhcp_acl_ip_address(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        Network *network = data;
+        Set **acl;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        acl = STR_IN_SET(lvalue, "DenyList", "BlackList") ? &network->dhcp_deny_listed_ip : &network->dhcp_allow_listed_ip;
+
+        if (isempty(rvalue)) {
+                *acl = set_free(*acl);
+                return 0;
+        }
+
+        for (const char *p = rvalue;;) {
+                _cleanup_free_ char *n = NULL;
+                union in_addr_union ip;
+
+                r = extract_first_word(&p, &n, NULL, 0);
+                if (r == -ENOMEM)
+                        return log_oom();
+                if (r < 0) {
+                        log_syntax(unit, LOG_WARNING, filename, line, r,
+                                   "Failed to parse DHCP '%s=' IP address, ignoring assignment: %s",
+                                   lvalue, rvalue);
+                        return 0;
+                }
+                if (r == 0)
+                        return 0;
+
+                r = in_addr_from_string(AF_INET, n, &ip);
+                if (r < 0) {
+                        log_syntax(unit, LOG_WARNING, filename, line, r,
+                                   "DHCP '%s=' IP address is invalid, ignoring assignment: %s", lvalue, n);
+                        continue;
+                }
+
+                r = set_ensure_put(acl, NULL, UINT32_TO_PTR(ip.in.s_addr));
+                if (r < 0)
+                        log_syntax(unit, LOG_WARNING, filename, line, r,
+                                   "Failed to store DHCP '%s=' IP address '%s', ignoring assignment: %m", lvalue, n);
+        }
+}
+
+int config_parse_dhcp_ip_service_type(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+
+        if (streq(rvalue, "CS4"))
+                *((int *)data) = IPTOS_CLASS_CS4;
+        else if (streq(rvalue, "CS6"))
+                *((int *)data) = IPTOS_CLASS_CS6;
+        else
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "Failed to parse IPServiceType type '%s', ignoring.", rvalue);
+
+        return 0;
+}
+
+int config_parse_dhcp_mud_url(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        _cleanup_free_ char *unescaped = NULL;
+        Network *network = data;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+
+        if (isempty(rvalue)) {
+                network->dhcp_mudurl = mfree(network->dhcp_mudurl);
+                return 0;
+        }
+
+        r = cunescape(rvalue, 0, &unescaped);
+        if (r < 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, r,
+                           "Failed to Failed to unescape MUD URL, ignoring: %s", rvalue);
+                return 0;
+        }
+
+        if (!http_url_is_valid(unescaped) || strlen(unescaped) > 255) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "Failed to parse MUD URL '%s', ignoring: %m", rvalue);
+
+                return 0;
+        }
+
+        return free_and_strdup_warn(&network->dhcp_mudurl, unescaped);
+}
+
+int config_parse_dhcp_fallback_lease_lifetime(const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+        Network *network = userdata;
+        uint32_t k;
+
+        assert(filename);
+        assert(section);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        if (isempty(rvalue)) {
+                network->dhcp_fallback_lease_lifetime = 0;
+                return 0;
+        }
+
+        /* We accept only "forever" or "infinity". */
+        if (STR_IN_SET(rvalue, "forever", "infinity"))
+                k = CACHE_INFO_INFINITY_LIFE_TIME;
+        else {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "Invalid LeaseLifetime= value, ignoring: %s", rvalue);
+                return 0;
+        }
+
+        network->dhcp_fallback_lease_lifetime = k;
+
+        return 0;
+}
+
+static const char* const dhcp_client_identifier_table[_DHCP_CLIENT_ID_MAX] = {
+        [DHCP_CLIENT_ID_MAC] = "mac",
+        [DHCP_CLIENT_ID_DUID] = "duid",
+        [DHCP_CLIENT_ID_DUID_ONLY] = "duid-only",
+};
+
+DEFINE_PRIVATE_STRING_TABLE_LOOKUP_FROM_STRING(dhcp_client_identifier, DHCPClientIdentifier);
+DEFINE_CONFIG_PARSE_ENUM(config_parse_dhcp_client_identifier, dhcp_client_identifier, DHCPClientIdentifier,
+                         "Failed to parse client identifier type");