Adding upstream version 241.upstream/241upstream

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

1 files changed, 822 insertions, 0 deletions

diff --git a/src/network/networkd-dhcp4.c b/src/network/networkd-dhcp4.c
new file mode 100644
index 0000000..d8ac455
--- /dev/null
+++ b/src/network/networkd-dhcp4.c
@@ -0,0 +1,822 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <netinet/ether.h>
+#include <linux/if.h>
+
+#include "alloc-util.h"
+#include "hostname-util.h"
+#include "parse-util.h"
+#include "netdev/vrf.h"
+#include "network-internal.h"
+#include "networkd-link.h"
+#include "networkd-manager.h"
+#include "networkd-network.h"
+#include "string-util.h"
+#include "sysctl-util.h"
+
+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--;
+
+        r = sd_netlink_message_get_errno(m);
+        if (r < 0 && r != -EEXIST) {
+                log_link_error_errno(link, r, "Could not set DHCPv4 route: %m");
+                link_enter_failed(link);
+        }
+
+        if (link->dhcp4_messages == 0) {
+                link->dhcp4_configured = true;
+                link_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 (in_addr_is_localhost(AF_INET, &route->dst) ||
+            (self_addr->s_addr && route->dst.in.s_addr == self_addr->s_addr))
+                return RT_SCOPE_HOST;
+        else if (in4_addr_is_null(&route->gw.in))
+                return RT_SCOPE_LINK;
+        else
+                return RT_SCOPE_UNIVERSE;
+}
+
+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 gateway, address;
+        int r, n, i;
+        uint32_t table;
+
+        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->network->dhcp_use_routes)
+                return 0;
+
+        /* When the interface is part of an VRF use the VRFs routing table, unless
+         * there is a another table specified. */
+        table = link->network->dhcp_route_table;
+        if (!link->network->dhcp_route_table_set && link->network->vrf != NULL)
+                table = VRF(link->network->vrf)->table;
+
+        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");
+
+        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)
+                log_link_debug_errno(link, n, "DHCP error: could not get routes: %m");
+
+        for (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;
+                }
+        }
+
+        for (i = 0; i < n; i++) {
+                _cleanup_(route_freep) Route *route = NULL;
+
+                /* 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 &&
+                    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;
+                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->scope = route_scope_from_address(route, &address);
+
+                r = route_configure(route, link, dhcp4_route_handler);
+                if (r < 0)
+                        return log_link_warning_errno(link, r, "Could not set host route: %m");
+
+                link->dhcp4_messages++;
+        }
+
+        r = sd_dhcp_lease_get_router(link->dhcp_lease, &gateway);
+        if (r == -ENODATA)
+                log_link_info_errno(link, r, "DHCP: No gateway received from DHCP server: %m");
+        else if (r < 0)
+                log_link_warning_errno(link, r, "DHCP error: could not get gateway: %m");
+
+        /* 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. */
+        if (classless_route && static_route)
+                log_link_warning(link, "Classless static routes received from DHCP server: ignoring static-route option and router option");
+
+        if (r >= 0 && !classless_route) {
+                _cleanup_(route_freep) Route *route = NULL;
+                _cleanup_(route_freep) Route *route_gw = NULL;
+
+                r = route_new(&route);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Could not allocate route: %m");
+
+                route->protocol = RTPROT_DHCP;
+
+                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 = gateway;
+                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;
+
+                r = route_configure(route_gw, link, dhcp4_route_handler);
+                if (r < 0)
+                        return log_link_warning_errno(link, r, "Could not set host route: %m");
+
+                link->dhcp4_messages++;
+
+                route->family = AF_INET;
+                route->gw.in = gateway;
+                route->prefsrc.in = address;
+                route->priority = link->network->dhcp_route_metric;
+                route->table = table;
+
+                r = route_configure(route, link, dhcp4_route_handler);
+                if (r < 0) {
+                        log_link_warning_errno(link, r, "Could not set routes: %m");
+                        link_enter_failed(link);
+                        return r;
+                }
+
+                link->dhcp4_messages++;
+        }
+
+        return 0;
+}
+
+static int dhcp_lease_lost(Link *link) {
+        _cleanup_(address_freep) Address *address = NULL;
+        struct in_addr addr;
+        struct in_addr netmask;
+        struct in_addr gateway;
+        unsigned prefixlen = 0;
+        int r;
+
+        assert(link);
+        assert(link->dhcp_lease);
+
+        log_link_warning(link, "DHCP lease lost");
+
+        if (link->network->dhcp_use_routes) {
+                _cleanup_free_ sd_dhcp_route **routes = NULL;
+                int n, i;
+
+                n = sd_dhcp_lease_get_routes(link->dhcp_lease, &routes);
+                if (n >= 0) {
+                        for (i = 0; i < n; i++) {
+                                _cleanup_(route_freep) Route *route = NULL;
+
+                                r = route_new(&route);
+                                if (r >= 0) {
+                                        route->family = AF_INET;
+                                        assert_se(sd_dhcp_route_get_gateway(routes[i], &route->gw.in) >= 0);
+                                        assert_se(sd_dhcp_route_get_destination(routes[i], &route->dst.in) >= 0);
+                                        assert_se(sd_dhcp_route_get_destination_prefix_length(routes[i], &route->dst_prefixlen) >= 0);
+
+                                        route_remove(route, link, NULL);
+                                }
+                        }
+                }
+        }
+
+        r = address_new(&address);
+        if (r >= 0) {
+                r = sd_dhcp_lease_get_router(link->dhcp_lease, &gateway);
+                if (r >= 0) {
+                        _cleanup_(route_freep) Route *route_gw = NULL;
+                        _cleanup_(route_freep) Route *route = NULL;
+
+                        r = route_new(&route_gw);
+                        if (r >= 0) {
+                                route_gw->family = AF_INET;
+                                route_gw->dst.in = gateway;
+                                route_gw->dst_prefixlen = 32;
+                                route_gw->scope = RT_SCOPE_LINK;
+
+                                route_remove(route_gw, link, NULL);
+                        }
+
+                        r = route_new(&route);
+                        if (r >= 0) {
+                                route->family = AF_INET;
+                                route->gw.in = gateway;
+
+                                route_remove(route, link, NULL);
+                        }
+                }
+
+                r = sd_dhcp_lease_get_address(link->dhcp_lease, &addr);
+                if (r >= 0) {
+                        r = sd_dhcp_lease_get_netmask(link->dhcp_lease, &netmask);
+                        if (r >= 0)
+                                prefixlen = in4_addr_netmask_to_prefixlen(&netmask);
+
+                        address->family = AF_INET;
+                        address->in_addr.in = addr;
+                        address->prefixlen = prefixlen;
+
+                        address_remove(address, link, NULL);
+                }
+        }
+
+        if (link->network->dhcp_use_mtu) {
+                uint16_t mtu;
+
+                r = sd_dhcp_lease_get_mtu(link->dhcp_lease, &mtu);
+                if (r >= 0 && link->original_mtu != mtu) {
+                        r = link_set_mtu(link, link->original_mtu);
+                        if (r < 0) {
+                                log_link_warning(link,
+                                                 "DHCP error: could not reset MTU");
+                                link_enter_failed(link);
+                                return r;
+                        }
+                }
+        }
+
+        if (link->network->dhcp_use_hostname) {
+                const char *hostname = NULL;
+
+                if (link->network->dhcp_hostname)
+                        hostname = link->network->dhcp_hostname;
+                else
+                        (void) sd_dhcp_lease_get_hostname(link->dhcp_lease, &hostname);
+
+                if (hostname) {
+                        /* If a hostname was set due to the lease, then unset it now. */
+                        r = manager_set_hostname(link->manager, NULL);
+                        if (r < 0)
+                                log_link_warning_errno(link, r, "Failed to reset transient hostname: %m");
+                }
+        }
+
+        link->dhcp_lease = sd_dhcp_lease_unref(link->dhcp_lease);
+        link_dirty(link);
+        link->dhcp4_configured = false;
+
+        return 0;
+}
+
+static int dhcp4_address_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
+        int r;
+
+        assert(link);
+
+        r = sd_netlink_message_get_errno(m);
+        if (r < 0 && r != -EEXIST) {
+                log_link_error_errno(link, r, "Could not set DHCPv4 address: %m");
+                link_enter_failed(link);
+        } else if (r >= 0)
+                manager_rtnl_process_address(rtnl, m, link->manager);
+
+        link_set_dhcp_routes(link);
+
+        if (link->dhcp4_messages == 0) {
+                link->dhcp4_configured = true;
+                link_check_ready(link);
+        }
+
+        return 1;
+}
+
+static int dhcp4_update_address(Link *link,
+                                struct in_addr *address,
+                                struct in_addr *netmask,
+                                uint32_t lifetime) {
+        _cleanup_(address_freep) Address *addr = NULL;
+        unsigned prefixlen;
+        int r;
+
+        assert(address);
+        assert(netmask);
+        assert(lifetime);
+
+        prefixlen = in4_addr_netmask_to_prefixlen(netmask);
+
+        r = address_new(&addr);
+        if (r < 0)
+                return r;
+
+        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;
+        addr->broadcast.s_addr = address->s_addr | ~netmask->s_addr;
+
+        /* allow reusing an existing address and simply update its lifetime
+         * in case it already exists */
+        r = address_configure(addr, link, dhcp4_address_handler, true);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+static int dhcp_lease_renew(sd_dhcp_client *client, Link *link) {
+        sd_dhcp_lease *lease;
+        struct in_addr address;
+        struct in_addr netmask;
+        uint32_t lifetime = CACHE_INFO_INFINITY_LIFE_TIME;
+        int r;
+
+        assert(link);
+        assert(client);
+        assert(link->network);
+
+        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->dhcp4_configured = false;
+        link->dhcp_lease = sd_dhcp_lease_ref(lease);
+        link_dirty(link);
+
+        r = sd_dhcp_lease_get_address(lease, &address);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "DHCP error: no address: %m");
+
+        r = sd_dhcp_lease_get_netmask(lease, &netmask);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "DHCP error: no netmask: %m");
+
+        if (!link->network->dhcp_critical) {
+                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");
+        }
+
+        r = dhcp4_update_address(link, &address, &netmask, lifetime);
+        if (r < 0) {
+                log_link_warning_errno(link, r, "Could not update IP address: %m");
+                link_enter_failed(link);
+                return r;
+        }
+
+        return 0;
+}
+
+static int dhcp_lease_acquired(sd_dhcp_client *client, Link *link) {
+        sd_dhcp_lease *lease;
+        struct in_addr address;
+        struct in_addr netmask;
+        struct in_addr gateway;
+        unsigned prefixlen;
+        uint32_t lifetime = CACHE_INFO_INFINITY_LIFE_TIME;
+        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");
+
+        r = sd_dhcp_lease_get_address(lease, &address);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP error: No address: %m");
+
+        r = sd_dhcp_lease_get_netmask(lease, &netmask);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP error: No netmask: %m");
+
+        prefixlen = in4_addr_netmask_to_prefixlen(&netmask);
+
+        r = sd_dhcp_lease_get_router(lease, &gateway);
+        if (r < 0 && r != -ENODATA)
+                return log_link_error_errno(link, r, "DHCP error: Could not get gateway: %m");
+
+        if (r >= 0)
+                log_struct(LOG_INFO,
+                           LOG_LINK_INTERFACE(link),
+                           LOG_LINK_MESSAGE(link, "DHCPv4 address %u.%u.%u.%u/%u via %u.%u.%u.%u",
+                                            ADDRESS_FMT_VAL(address),
+                                            prefixlen,
+                                            ADDRESS_FMT_VAL(gateway)),
+                           "ADDRESS=%u.%u.%u.%u", ADDRESS_FMT_VAL(address),
+                           "PREFIXLEN=%u", prefixlen,
+                           "GATEWAY=%u.%u.%u.%u", ADDRESS_FMT_VAL(gateway));
+        else
+                log_struct(LOG_INFO,
+                           LOG_LINK_INTERFACE(link),
+                           LOG_LINK_MESSAGE(link, "DHCPv4 address %u.%u.%u.%u/%u",
+                                            ADDRESS_FMT_VAL(address),
+                                            prefixlen),
+                           "ADDRESS=%u.%u.%u.%u", ADDRESS_FMT_VAL(address),
+                           "PREFIXLEN=%u", prefixlen);
+
+        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 DCHP 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->network->dhcp_critical) {
+                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");
+        }
+
+        r = dhcp4_update_address(link, &address, &netmask, lifetime);
+        if (r < 0) {
+                log_link_warning_errno(link, r, "Could not update IP address: %m");
+                link_enter_failed(link);
+                return r;
+        }
+
+        return 0;
+}
+static void dhcp4_handler(sd_dhcp_client *client, int event, void *userdata) {
+        Link *link = userdata;
+        int r = 0;
+
+        assert(link);
+        assert(link->network);
+        assert(link->manager);
+
+        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
+                return;
+
+        switch (event) {
+                case SD_DHCP_CLIENT_EVENT_EXPIRED:
+                case SD_DHCP_CLIENT_EVENT_STOP:
+                case SD_DHCP_CLIENT_EVENT_IP_CHANGE:
+                        if (link->network->dhcp_critical) {
+                                log_link_error(link, "DHCPv4 connection considered system critical, ignoring request to reconfigure it.");
+                                return;
+                        }
+
+                        if (link->dhcp_lease) {
+                                r = dhcp_lease_lost(link);
+                                if (r < 0) {
+                                        link_enter_failed(link);
+                                        return;
+                                }
+                        }
+
+                        if (event == SD_DHCP_CLIENT_EVENT_IP_CHANGE) {
+                                r = dhcp_lease_acquired(client, link);
+                                if (r < 0) {
+                                        link_enter_failed(link);
+                                        return;
+                                }
+                        }
+
+                        break;
+                case SD_DHCP_CLIENT_EVENT_RENEW:
+                        r = dhcp_lease_renew(client, link);
+                        if (r < 0) {
+                                link_enter_failed(link);
+                                return;
+                        }
+                        break;
+                case SD_DHCP_CLIENT_EVENT_IP_ACQUIRE:
+                        r = dhcp_lease_acquired(client, link);
+                        if (r < 0) {
+                                link_enter_failed(link);
+                                return;
+                        }
+                        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;
+}
+
+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
+ */
+int dhcp4_set_promote_secondaries(Link *link) {
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(link->network->dhcp & ADDRESS_FAMILY_IPV4);
+
+        /* 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;
+}
+
+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:
+                r = sd_dhcp_client_set_client_id(link->dhcp_client,
+                                                 ARPHRD_ETHER,
+                                                 (const uint8_t *) &link->mac,
+                                                 sizeof(link->mac));
+                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;
+}
+
+int dhcp4_configure(Link *link) {
+        int r;
+
+        assert(link);
+        assert(link->network);
+        assert(link->network->dhcp & ADDRESS_FAMILY_IPV4);
+
+        if (!link->dhcp_client) {
+                r = sd_dhcp_client_new(&link->dhcp_client, link->network->dhcp_anonymize);
+                if (r == -ENOMEM)
+                        return log_oom();
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to create DHCP4 client: %m");
+        }
+
+        r = sd_dhcp_client_attach_event(link->dhcp_client, NULL, 0);
+        if (r < 0)
+                return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to attach event: %m");
+
+        r = sd_dhcp_client_set_mac(link->dhcp_client,
+                                   (const uint8_t *) &link->mac,
+                                   sizeof (link->mac), ARPHRD_ETHER);
+        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_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_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");
+        }
+
+        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_user_class) {
+                r = sd_dhcp_client_set_user_class(link->dhcp_client, (const char **) 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");
+        }
+
+        return dhcp4_set_client_identifier(link);
+}