networkd/dhcp6: Add support for IPv6 SIP servers (#38269)

This pull-request adds support for IPv6 SIP servers, which can be obtained from DHCPv6 options. [RFC3319](https://www.rfc-editor.org/rfc/rfc3319.html) defines two options for this: option 21 (SIP Servers Domain Name List) and option 22 (SIP Servers IPv6 Address List). systemd-networkd currently only supports IPv4 SIP servers, but ISPs like NTT EAST provide IPv6 SIP servers. Exposing this in the D-Bus API would allow other programs, such as downstream DHCPv6 servers, to utilize it. Usage: ``` [DHCPv6] UseSIP=yes ``` Partial output of `run0 systemd-networkd-tests.py NetworkdDHCPClientTests.test_dhcp_client_use_sip`: ```console > networkctl status veth99 ● 17: veth99 NetDev File: /run/systemd/network/25-veth.netdev Link File: /usr/lib/systemd/network/99-default.link Network File: /run/systemd/network/25-dhcp-client.network └─/run/systemd/network/25-dhcp-client.network.d/override.conf State: routable (configured) Online state: online Type: ether Kind: veth Driver: veth Hardware Address: 12:34:56:78:9a:bc MTU: 1500 (min: 68, max: 65535) QDisc: noqueue IPv6 Address Generation Mode: eui64 Number of Queues (Tx/Rx): 2/2 Auto negotiation: no Speed: 10Gbps Duplex: full Port: tp Address: 192.168.5.181 (DHCPv4 via 192.168.5.1) 2600::15 fe80::1034:56ff:fe78:9abc Gateway: 192.168.5.1 fe80::1034:56ff:fe78:9abd SIP: 192.168.5.1 2600::1 foo.example.com Activation Policy: up Required For Online: yes DHCPv4 Client ID: IAID:0x7ec6b6c/DUID DHCPv6 Client IAID: 0x7ec6b6c DHCPv6 Client DUID: DUID-EN/Vendor:0000ab11617740de1342c3a2 ```
2026-04-14 00:14:32 +09:00 · 2025-07-23 08:09:06 +09:00
parent 8acee7c35e 3a83ea5bf2
commit 3eb5402b5c
12 changed files with 257 additions and 34 deletions
--- a/man/systemd.network.xml
+++ b/man/systemd.network.xml
@@ -3233,6 +3233,7 @@ NFTSet=prefix:netdev:filter:eth_ipv4_prefix</programlisting>
        <term><varname>UseDNS=</varname></term>
        <term><varname>UseDNR=</varname></term>
        <term><varname>UseNTP=</varname></term>
+        <term><varname>UseSIP=</varname></term>
        <term><varname>UseHostname=</varname></term>
        <term><varname>UseDomains=</varname></term>
        <term><varname>NetLabel=</varname></term>
--- a/src/libsystemd-network/dhcp6-lease-internal.h
+++ b/src/libsystemd-network/dhcp6-lease-internal.h
@@ -43,6 +43,9 @@ struct sd_dhcp6_lease {
        char **ntp_fqdn;
        struct in6_addr *sntp;
        size_t sntp_count;
+        struct in6_addr *sip;
+        size_t sip_count;
+        char **sip_domains;
        char *fqdn;
        char *captive_portal;
        struct sd_dhcp6_option **sorted_vendor_options;
@@ -62,6 +65,8 @@ int dhcp6_lease_add_dns(sd_dhcp6_lease *lease, const uint8_t *optval, size_t opt
 int dhcp6_lease_add_domains(sd_dhcp6_lease *lease, const uint8_t *optval, size_t optlen);
 int dhcp6_lease_add_ntp(sd_dhcp6_lease *lease, const uint8_t *optval, size_t optlen);
 int dhcp6_lease_add_sntp(sd_dhcp6_lease *lease, const uint8_t *optval, size_t optlen);
+int dhcp6_lease_add_sip_addrs(sd_dhcp6_lease *lease, const uint8_t *optval, size_t optlen);
+int dhcp6_lease_add_sip_domains(sd_dhcp6_lease *lease, const uint8_t *optval, size_t optlen);
 int dhcp6_lease_set_fqdn(sd_dhcp6_lease *lease, const uint8_t *optval, size_t optlen);
 int dhcp6_lease_set_captive_portal(sd_dhcp6_lease *lease, const uint8_t *optval, size_t optlen);

--- a/src/libsystemd-network/sd-dhcp6-lease.c
+++ b/src/libsystemd-network/sd-dhcp6-lease.c
@@ -629,6 +629,56 @@ int sd_dhcp6_lease_get_ntp_fqdn(sd_dhcp6_lease *lease, char ***ret) {
        return strv_length(lease->ntp_fqdn);
 }

+int dhcp6_lease_add_sip_addrs(sd_dhcp6_lease *lease, const uint8_t *optval, size_t optlen) {
+        assert(lease);
+        assert(optval || optlen == 0);
+
+        if (optlen == 0)
+                return 0;
+
+        return dhcp6_option_parse_addresses(optval, optlen, &lease->sip, &lease->sip_count);
+}
+
+int sd_dhcp6_lease_get_sip_addrs(sd_dhcp6_lease *lease, const struct in6_addr **ret) {
+        assert_return(lease, -EINVAL);
+
+        if (lease->sip) {
+                if (ret)
+                        *ret = lease->sip;
+                return lease->sip_count;
+        }
+
+        return -ENODATA;
+}
+
+int dhcp6_lease_add_sip_domains(sd_dhcp6_lease *lease, const uint8_t *optval, size_t optlen) {
+        _cleanup_strv_free_ char **domains = NULL;
+        int r;
+
+        assert(lease);
+        assert(optval || optlen == 0);
+
+        if (optlen == 0)
+                return 0;
+
+        r = dhcp6_option_parse_domainname_list(optval, optlen, &domains);
+        if (r < 0)
+                return r;
+
+        return strv_extend_strv_consume(&lease->sip_domains, TAKE_PTR(domains), /* filter_duplicates = */ true);
+}
+
+int sd_dhcp6_lease_get_sip_domains(sd_dhcp6_lease *lease, char ***ret) {
+        assert_return(lease, -EINVAL);
+        assert_return(ret, -EINVAL);
+
+        if (!lease->sip_domains)
+                return -ENODATA;
+
+        *ret = lease->sip_domains;
+        return strv_length(lease->sip_domains);
+}
+
 int dhcp6_lease_set_fqdn(sd_dhcp6_lease *lease, const uint8_t *optval, size_t optlen) {
        char *fqdn;
        int r;
@@ -930,6 +980,19 @@ static int dhcp6_lease_parse_message(

                        break;

+                case SD_DHCP6_OPTION_SIP_SERVER_ADDRESS:
+                        r = dhcp6_lease_add_sip_addrs(lease, optval, optlen);
+                        if (r < 0)
+                                log_dhcp6_client_errno(client, r, "Failed to parse SIP server address option, ignoring: %m");
+
+                        break;
+
+                case SD_DHCP6_OPTION_SIP_SERVER_DOMAIN_NAME:
+                        r = dhcp6_lease_add_sip_domains(lease, optval, optlen);
+                        if (r < 0)
+                                log_dhcp6_client_errno(client, r, "Failed to parse SIP server domain name option, ignoring: %m");
+                        break;
+
                case SD_DHCP6_OPTION_CAPTIVE_PORTAL:
                        r = dhcp6_lease_set_captive_portal(lease, optval, optlen);
                        if (r < 0)
@@ -1020,6 +1083,8 @@ static sd_dhcp6_lease *dhcp6_lease_free(sd_dhcp6_lease *lease) {
        free(lease->ntp);
        strv_free(lease->ntp_fqdn);
        free(lease->sntp);
+        free(lease->sip);
+        strv_free(lease->sip_domains);

        return mfree(lease);
 }
--- a/src/libsystemd-network/test-dhcp6-client.c
+++ b/src/libsystemd-network/test-dhcp6-client.c
@@ -47,6 +47,10 @@
        0x20, 0x01, 0x0d, 0xb8, 0xde, 0xad, 0xbe, 0xef, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x05
 #define NTP2_BYTES                                                      \
        0x20, 0x01, 0x0d, 0xb8, 0xde, 0xad, 0xbe, 0xef, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06
+#define SIP1_BYTES                                                      \
+        0x20, 0x01, 0x0d, 0xb8, 0xde, 0xad, 0xbe, 0xef, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07
+#define SIP2_BYTES                                                      \
+        0x20, 0x01, 0x0d, 0xb8, 0xde, 0xad, 0xbe, 0xef, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08
 #define CLIENT_ID_BYTES                                                 \
        0x00, 0x02, 0x00, 0x00, 0xab, 0x11, 0x61, 0x77, 0x40, 0xde, 0x13, 0x42, 0xc3, 0xa2
 #define SERVER_ID_BYTES                                                 \
@@ -67,6 +71,8 @@ static const struct in6_addr sntp1 = { { { SNTP1_BYTES } } };
 static const struct in6_addr sntp2 = { { { SNTP2_BYTES } } };
 static const struct in6_addr ntp1 = { { { NTP1_BYTES } } };
 static const struct in6_addr ntp2 = { { { NTP2_BYTES } } };
+static const struct in6_addr sip1 = { { { SIP1_BYTES } } };
+static const struct in6_addr sip2 = { { { SIP2_BYTES } } };
 static const uint8_t client_id[] = { CLIENT_ID_BYTES };
 static const uint8_t server_id[] = { SERVER_ID_BYTES };
 static uint8_t vendor_suboption_data[] = { VENDOR_SUBOPTION_BYTES };
@@ -107,6 +113,8 @@ TEST(client_basic) {
        assert_se(sd_dhcp6_client_set_request_option(client, SD_DHCP6_OPTION_DNS_SERVER) >= 0);
        assert_se(sd_dhcp6_client_set_request_option(client, SD_DHCP6_OPTION_NTP_SERVER) >= 0);
        assert_se(sd_dhcp6_client_set_request_option(client, SD_DHCP6_OPTION_SNTP_SERVER) >= 0);
+        assert_se(sd_dhcp6_client_set_request_option(client, SD_DHCP6_OPTION_SIP_SERVER_ADDRESS) >= 0);
+        assert_se(sd_dhcp6_client_set_request_option(client, SD_DHCP6_OPTION_SIP_SERVER_DOMAIN_NAME) >= 0);
        assert_se(sd_dhcp6_client_set_request_option(client, SD_DHCP6_OPTION_VENDOR_OPTS) >= 0);
        assert_se(sd_dhcp6_client_set_request_option(client, SD_DHCP6_OPTION_DOMAIN) >= 0);
        assert_se(sd_dhcp6_client_set_request_option(client, 10) == -EINVAL);
@@ -737,6 +745,13 @@ static const uint8_t msg_reply[] = {
        /* NTP server (fqdn suboption) */
        0x00, DHCP6_NTP_SUBOPTION_SRV_FQDN, 0x00, 0x0b,
        0x03, 'n', 't', 'p', 0x05, 'i', 'n', 't', 'r', 'a', 0x00,
+        /* SIP server addresses */
+        0x00, SD_DHCP6_OPTION_SIP_SERVER_ADDRESS, 0x00, 0x20,
+        SIP1_BYTES,
+        SIP2_BYTES,
+        /* SIP server domains */
+        0x00, SD_DHCP6_OPTION_SIP_SERVER_DOMAIN_NAME, 0x00, 0x0b,
+        0x03, 's', 'i', 'p', 0x05, 'i', 'n', 't', 'r', 'a', 0x00,
        /* Domain list */
        0x00, SD_DHCP6_OPTION_DOMAIN, 0x00, 0x0b,
        0x03, 'l', 'a', 'b', 0x05, 'i', 'n', 't', 'r', 'a', 0x00,
@@ -819,6 +834,13 @@ static const uint8_t msg_advertise[] = {
        /* NTP server (fqdn suboption) */
        0x00, DHCP6_NTP_SUBOPTION_SRV_FQDN, 0x00, 0x0b,
        0x03, 'n', 't', 'p', 0x05, 'i', 'n', 't', 'r', 'a', 0x00,
+        /* SIP server addresses */
+        0x00, SD_DHCP6_OPTION_SIP_SERVER_ADDRESS, 0x00, 0x20,
+        SIP1_BYTES,
+        SIP2_BYTES,
+        /* SIP server domains */
+        0x00, SD_DHCP6_OPTION_SIP_SERVER_DOMAIN_NAME, 0x00, 0x0b,
+        0x03, 's', 'i', 'p', 0x05, 'i', 'n', 't', 'r', 'a', 0x00,
        /* Domain list */
        0x00, SD_DHCP6_OPTION_DOMAIN, 0x00, 0x0b,
        0x03, 'l', 'a', 'b', 0x05, 'i', 'n', 't', 'r', 'a', 0x00,
@@ -899,6 +921,14 @@ static void test_lease_common(sd_dhcp6_client *client) {
        assert_se(streq(strv[0], "ntp.intra"));
        assert_se(!strv[1]);

+        assert_se(sd_dhcp6_lease_get_sip_addrs(lease, &addrs) == 2);
+        assert_se(in6_addr_equal(&addrs[0], &sip1));
+        assert_se(in6_addr_equal(&addrs[1], &sip2));
+
+        assert_se(sd_dhcp6_lease_get_sip_domains(lease, &strv) == 1);
+        assert_se(streq(strv[0], "sip.intra"));
+        assert_se(!strv[1]);
+
        assert_se(lease->sntp_count == 2);
        assert_se(in6_addr_equal(&lease->sntp[0], &sntp1));
        assert_se(in6_addr_equal(&lease->sntp[1], &sntp2));
--- a/src/network/networkd-dhcp6.c
+++ b/src/network/networkd-dhcp6.c
@@ -687,6 +687,16 @@ static int dhcp6_configure(Link *link) {
                        return log_link_debug_errno(link, r, "DHCPv6 CLIENT: Failed to request SNTP servers: %m");
        }

+        if (link->network->dhcp6_use_sip > 0) {
+                r = sd_dhcp6_client_set_request_option(client, SD_DHCP6_OPTION_SIP_SERVER_ADDRESS);
+                if (r < 0)
+                        return log_link_debug_errno(link, r, "DHCPv6 CLIENT: Failed to request SIP servers: %m");
+
+                r = sd_dhcp6_client_set_request_option(client, SD_DHCP6_OPTION_SIP_SERVER_DOMAIN_NAME);
+                if (r < 0)
+                        return log_link_debug_errno(link, r, "DHCPv6 CLIENT: Failed to request SIP server domain names: %m");
+        }
+
        SET_FOREACH(request_options, link->network->dhcp6_request_options) {
                uint32_t option = PTR_TO_UINT32(request_options);

--- a/src/network/networkd-json.c
+++ b/src/network/networkd-json.c
@@ -819,39 +819,6 @@ static int ntp_append_json(Link *link, sd_json_variant **v) {
        return json_variant_set_field_non_null(v, "NTP", array);
 }

-static int sip_append_json(Link *link, sd_json_variant **v) {
-        _cleanup_(sd_json_variant_unrefp) sd_json_variant *array = NULL;
-        const struct in_addr *sip;
-        union in_addr_union s;
-        int n_sip, r;
-
-        assert(link);
-        assert(v);
-
-        if (!link->network || !link->network->dhcp_use_sip || !link->dhcp_lease)
-                return 0;
-
-        n_sip = sd_dhcp_lease_get_sip(link->dhcp_lease, &sip);
-        if (n_sip <= 0)
-                return 0;
-
-        r = sd_dhcp_lease_get_server_identifier(link->dhcp_lease, &s.in);
-        if (r < 0)
-                return r;
-
-        for (int i = 0; i < n_sip; i++) {
-                r = server_append_json_one_addr(AF_INET,
-                                                &(union in_addr_union) { .in = sip[i], },
-                                                NETWORK_CONFIG_SOURCE_DHCP4,
-                                                &s,
-                                                &array);
-                if (r < 0)
-                        return r;
-        }
-
-        return json_variant_set_field_non_null(v, "SIP", array);
-}
-
 static int domain_append_json(int family, const char *domain, NetworkConfigSource s, const union in_addr_union *p, sd_json_variant **array) {
        assert(IN_SET(family, AF_UNSPEC, AF_INET, AF_INET6));
        assert(domain);
@@ -864,6 +831,78 @@ static int domain_append_json(int family, const char *domain, NetworkConfigSourc
                        JSON_BUILD_PAIR_IN_ADDR_NON_NULL("ConfigProvider", p, family));
 }

+static int sip_append_json(Link *link, sd_json_variant **v) {
+        _cleanup_(sd_json_variant_unrefp) sd_json_variant *array = NULL;
+        int r;
+
+        assert(link);
+        assert(v);
+
+        if (!link->network)
+                return 0;
+
+        if (link->dhcp_lease && link->network->dhcp_use_sip) {
+                const struct in_addr *sip;
+                union in_addr_union s;
+                int n_sip;
+
+                n_sip = sd_dhcp_lease_get_sip(link->dhcp_lease, &sip);
+                if (n_sip <= 0)
+                        return 0;
+
+                r = sd_dhcp_lease_get_server_identifier(link->dhcp_lease, &s.in);
+                if (r < 0)
+                        return r;
+
+                for (int i = 0; i < n_sip; i++) {
+                        r = server_append_json_one_addr(AF_INET,
+                                                        &(union in_addr_union) { .in = sip[i], },
+                                                        NETWORK_CONFIG_SOURCE_DHCP4,
+                                                        &s,
+                                                        &array);
+                        if (r < 0)
+                                return r;
+                }
+
+        }
+
+        if (link->dhcp6_lease && link->network->dhcp6_use_sip) {
+                const struct in6_addr *sip_addr;
+                union in_addr_union s;
+                char **domains;
+                int n_sip;
+
+                r = sd_dhcp6_lease_get_server_address(link->dhcp6_lease, &s.in6);
+                if (r < 0)
+                        return r;
+
+                n_sip = sd_dhcp6_lease_get_sip_addrs(link->dhcp6_lease, &sip_addr);
+                for (int i = 0; i < n_sip; i++) {
+                        r = server_append_json_one_addr(AF_INET6,
+                                                        &(union in_addr_union) { .in6 = sip_addr[i], },
+                                                        NETWORK_CONFIG_SOURCE_DHCP6,
+                                                        &s,
+                                                        &array);
+                        if (r < 0)
+                                return r;
+                }
+
+                if (sd_dhcp6_lease_get_sip_domains(link->dhcp6_lease, &domains) >= 0)
+                        STRV_FOREACH(p, domains) {
+                                r = domain_append_json(AF_INET6,
+                                                       *p,
+                                                       NETWORK_CONFIG_SOURCE_DHCP6,
+                                                       &s,
+                                                       &array);
+                                if (r < 0)
+                                        return r;
+                        }
+
+        }
+
+        return json_variant_set_field_non_null(v, "SIP", array);
+}
+
 static int domains_append_json(Link *link, bool is_route, sd_json_variant **v) {
        _cleanup_(sd_json_variant_unrefp) sd_json_variant *array = NULL;
        OrderedSet *link_domains, *network_domains;
--- a/src/network/networkd-network-gperf.gperf
+++ b/src/network/networkd-network-gperf.gperf
@@ -310,6 +310,7 @@ DHCPv6.UseDNR,                               config_parse_tristate,
 DHCPv6.UseHostname,                          config_parse_bool,                                        0,                             offsetof(Network, dhcp6_use_hostname)
 DHCPv6.UseDomains,                           config_parse_use_domains,                                 0,                             offsetof(Network, dhcp6_use_domains)
 DHCPv6.UseNTP,                               config_parse_tristate,                                    0,                             offsetof(Network, dhcp6_use_ntp)
+DHCPv6.UseSIP,                               config_parse_bool,                                        0,                             offsetof(Network, dhcp6_use_sip)
 DHCPv6.UseCaptivePortal,                     config_parse_bool,                                        0,                             offsetof(Network, dhcp6_use_captive_portal)
 DHCPv6.MUDURL,                               config_parse_mud_url,                                     0,                             offsetof(Network, dhcp6_mudurl)
 DHCPv6.SendHostname,                         config_parse_dhcp_send_hostname,                          AF_INET6,                      0
--- a/src/network/networkd-network.c
+++ b/src/network/networkd-network.c
@@ -413,6 +413,7 @@ int network_load_one(Manager *manager, OrderedHashmap **networks, const char *fi
                .dhcp6_use_domains = _USE_DOMAINS_INVALID,
                .dhcp6_use_hostname = true,
                .dhcp6_use_ntp = -1,
+                .dhcp6_use_sip = true,
                .dhcp6_use_captive_portal = true,
                .dhcp6_use_rapid_commit = true,
                .dhcp6_send_hostname = true,
--- a/src/network/networkd-network.h
+++ b/src/network/networkd-network.h
@@ -181,6 +181,7 @@ typedef struct Network {
        int dhcp6_use_dnr;
        bool dhcp6_use_hostname;
        int dhcp6_use_ntp;
+        bool dhcp6_use_sip;
        bool dhcp6_use_captive_portal;
        bool dhcp6_use_rapid_commit;
        UseDomains dhcp6_use_domains;
--- a/src/network/networkd-state-file.c
+++ b/src/network/networkd-state-file.c
@@ -264,6 +264,25 @@ static int link_put_sip(Link *link, OrderedSet **s) {
                }
        }

+        if (link->dhcp6_lease && link->network->dhcp6_use_sip) {
+                const struct in6_addr *addresses;
+                char **domains;
+
+                r = sd_dhcp6_lease_get_sip_addrs(link->dhcp6_lease, &addresses);
+                if (r >= 0) {
+                        r = ordered_set_put_in6_addrv(s, addresses, r);
+                        if (r < 0)
+                                return r;
+                }
+
+                r = sd_dhcp6_lease_get_sip_domains(link->dhcp6_lease, &domains);
+                if (r >= 0) {
+                        r = ordered_set_put_strdupv_full(s, &dns_name_hash_ops_free, domains);
+                        if (r < 0)
+                                return r;
+                }
+        }
+
        return 0;
 }

@@ -842,7 +861,10 @@ static int link_save(Link *link) {
                                    link->dhcp_lease,
                                    link->network->dhcp_use_sip,
                                    SD_DHCP_LEASE_SIP,
-                                    NULL, false, NULL, NULL);
+                                    link->dhcp6_lease,
+                                    link->network->dhcp6_use_sip,
+                                    sd_dhcp6_lease_get_sip_addrs,
+                                    sd_dhcp6_lease_get_sip_domains);

                /************************************************************/

--- a/src/systemd/sd-dhcp6-lease.h
+++ b/src/systemd/sd-dhcp6-lease.h
@@ -77,6 +77,8 @@ int sd_dhcp6_lease_get_dnr(sd_dhcp6_lease *lease, sd_dns_resolver **ret);
 int sd_dhcp6_lease_get_domains(sd_dhcp6_lease *lease, char ***ret);
 int sd_dhcp6_lease_get_ntp_addrs(sd_dhcp6_lease *lease, const struct in6_addr **ret);
 int sd_dhcp6_lease_get_ntp_fqdn(sd_dhcp6_lease *lease, char ***ret);
+int sd_dhcp6_lease_get_sip_addrs(sd_dhcp6_lease *lease, const struct in6_addr **ret);
+int sd_dhcp6_lease_get_sip_domains(sd_dhcp6_lease *lease, char ***ret);
 int sd_dhcp6_lease_get_fqdn(sd_dhcp6_lease *lease, const char **ret);
 int sd_dhcp6_lease_get_captive_portal(sd_dhcp6_lease *lease, const char **ret);
 int sd_dhcp6_lease_get_vendor_options(sd_dhcp6_lease *lease, sd_dhcp6_option ***ret);
--- a/test/test-network/systemd-networkd-tests.py
+++ b/test/test-network/systemd-networkd-tests.py
@@ -8433,6 +8433,52 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
        check(self, False, True, needs_reconfigure=True)
        check(self, False, False)

+    def test_dhcp_client_use_sip(self):
+        def check(self, ipv4, ipv6, needs_reconfigure=False):
+            os.makedirs(os.path.join(network_unit_dir, '25-dhcp-client.network.d'), exist_ok=True)
+            with open(os.path.join(network_unit_dir, '25-dhcp-client.network.d/override.conf'), mode='w', encoding='utf-8') as f:
+                f.write('[DHCPv4]\nUseSIP=')
+                f.write('yes' if ipv4 else 'no')
+                f.write('\n[DHCPv6]\nUseSIP=')
+                f.write('yes' if ipv6 else 'no')
+
+            networkctl_reload()
+            if needs_reconfigure:
+                networkctl_reconfigure('veth99')
+            self.wait_online('veth99:routable')
+
+            # link becomes 'routable' when at least one protocol provide an valid address. Hence, we need to explicitly wait for both addresses.
+            self.wait_address('veth99', r'inet 192.168.5.[0-9]*/24 metric 1024 brd 192.168.5.255 scope global dynamic', ipv='-4')
+            self.wait_address('veth99', r'inet6 2600::[0-9a-f]*/128 scope global (dynamic noprefixroute|noprefixroute dynamic)', ipv='-6')
+
+            output = networkctl_status('veth99')
+            print(output)
+            if ipv4 and ipv6:
+                self.assertRegex(output, 'SIP: 192.168.5.1\n *2600::1\n *foo.example.com')
+            elif ipv4:
+                self.assertIn('SIP: 192.168.5.1', output)
+            elif ipv6:
+                self.assertRegex(output, 'SIP: 2600::1\n *foo.example.com')
+            else:
+                self.assertNotIn('SIP: 192.168.5.1', output)
+                self.assertNotIn('SIP: 2600::1', output)
+                self.assertNotIn('SIP: foo.example.com', output)
+
+            check_json(networkctl_json())
+
+        copy_network_unit('25-veth.netdev', '25-dhcp-server-veth-peer.network', '25-dhcp-client.network', copy_dropins=False)
+
+        start_networkd()
+        self.wait_online('veth-peer:carrier')
+        start_dnsmasq('--dhcp-option=option:sip-server,192.168.5.1',
+                      '--dhcp-option=option6:sip-server,[2600::1]',
+                      '--dhcp-option=option6:sip-server-domain,foo.example.com')
+
+        check(self, True, True)
+        check(self, True, False)
+        check(self, False, True, needs_reconfigure=True)
+        check(self, False, False)
+
    def test_dhcp_client_use_captive_portal(self):
        def check(self, ipv4, ipv6, needs_reconfigure=False):
            os.makedirs(os.path.join(network_unit_dir, '25-dhcp-client.network.d'), exist_ok=True)