network: clean-up DHCP lease server data configuration

This is an attempt to clean up the POP3/SMTP/LPR/… DHCP lease server
data logic in networkd. This reduces code duplication and fixes a number
of bugs.

This removes any support for collecting POP3/SMPT/LPR servers acquired
via local DHCP client releases since noone uses that, and given how old
these protocols are I doubt this will change. It keeps support for
configuring them for the dhcp server however.

The differences between the DNS/NTP/SIP/POP3/SMTP/LPR configuration
logics are minimized.

This removes the relevant symbols from sd-network.h (which is an
internal API only at this point after all).

This is unfortunately not well test, given the old code for this had
barely any tests. But the new code should not perform worse at least,
and allow us to release, since it corrects some interfaces visible in
the .network configuration format.

Fixes: #15943

15 files changed, 178 insertions, 506 deletions

diff --git a/NEWS b/NEWS
index 6e65c637c8..7db370516a 100644
--- a/NEWS
+++ b/NEWS
@@ -76,7 +76,7 @@ CHANGES WITH 246 in spe:
           field.
 
         * systemd-networkd's [DHCPServer] section gained a new set of options
-          POP3Servers=, SMTPServers=, LPRServers= for including server
+          EmitPOP3=/POP3=, EmitSMTP=/SMTP=, EmitLPR=/LPR= for including server
           information about these three protocols in the DHCP lease. It also
           gained support for including "MUD" URLs ("Manufacturer Usage
           Description"). Support for "MUD" URLs was also added to the LLDP
diff --git a/man/systemd.network.xml b/man/systemd.network.xml
index 851570e723..c0d8d979e6 100644
--- a/man/systemd.network.xml
+++ b/man/systemd.network.xml
@@ -578,7 +578,7 @@
         <varlistentry>
           <term><varname>NTP=</varname></term>
           <listitem>
-            <para>An NTP server address. This option may be specified more than once. This setting is read by
+            <para>An NTP server address (either an IP address, or a hostname). This option may be specified more than once. This setting is read by
             <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
           </listitem>
         </varlistentry>
@@ -1412,17 +1412,16 @@
         <varlistentry>
           <term><varname>UseNTP=</varname></term>
           <listitem>
-            <para>When true (the default), the NTP servers received
-            from the DHCP server will be used by systemd-timesyncd
-            and take precedence over any statically configured ones.</para>
+            <para>When true (the default), the NTP servers received from the DHCP server will be used by
+            <filename>systemd-timesyncd.service</filename> and take precedence over any statically configured
+            ones.</para>
           </listitem>
         </varlistentry>
         <varlistentry>
           <term><varname>UseSIP=</varname></term>
           <listitem>
-            <para>When true (the default), the SIP servers received
-            from the DHCP server will be saved at the state files and can be
-            read via <function>sd_network_link_get_sip_servers()</function> function.</para>
+            <para>When true (the default), the SIP servers received from the DHCP server will be collected
+            and made available to client programs.</para>
           </listitem>
         </varlistentry>
 
@@ -2010,79 +2009,37 @@
         <term><varname>EmitDNS=</varname></term>
         <term><varname>DNS=</varname></term>
 
-        <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
-        to clients shall contain DNS server information. Defaults to <literal>yes</literal>.
-        The DNS servers to pass to clients may be configured with the
-        <varname>DNS=</varname> option, which takes a list of IPv4
-        addresses. If the <varname>EmitDNS=</varname> option is
-        enabled but no servers configured, the servers are
-        automatically propagated from an "uplink" interface that has
-        appropriate servers set. The "uplink" interface is determined
-        by the default route of the system with the highest
-        priority. Note that this information is acquired at the time
-        the lease is handed out, and does not take uplink interfaces
-        into account that acquire DNS or NTP server information at a
-        later point. DNS server propagation does not take
-        <filename>/etc/resolv.conf</filename> into account. Also, note
-        that the leases are not refreshed if the uplink network
-        configuration changes. To ensure clients regularly acquire the
-        most current uplink DNS server information, it is thus
-        advisable to shorten the DHCP lease time via
-        <varname>MaxLeaseTimeSec=</varname> described
+        <listitem><para><varname>EmitDNS=</varname> takes a boolean. Configures whether the DHCP leases
+        handed out to clients shall contain DNS server information. Defaults to <literal>yes</literal>.  The
+        DNS servers to pass to clients may be configured with the <varname>DNS=</varname> option, which takes
+        a list of IPv4 addresses. If the <varname>EmitDNS=</varname> option is enabled but no servers
+        configured, the servers are automatically propagated from an "uplink" interface that has appropriate
+        servers set. The "uplink" interface is determined by the default route of the system with the highest
+        priority. Note that this information is acquired at the time the lease is handed out, and does not
+        take uplink interfaces into account that acquire DNS server information at a later point. If no
+        suitable uplinkg interface is found the DNS server data from <filename>/etc/resolv.conf</filename> is
+        used. Also, note that the leases are not refreshed if the uplink network configuration changes. To
+        ensure clients regularly acquire the most current uplink DNS server information, it is thus advisable
+        to shorten the DHCP lease time via <varname>MaxLeaseTimeSec=</varname> described
         above.</para></listitem>
       </varlistentry>
 
       <varlistentry>
         <term><varname>EmitNTP=</varname></term>
         <term><varname>NTP=</varname></term>
-
-        <listitem><para>Similar to the <varname>EmitDNS=</varname> and
-        <varname>DNS=</varname> settings described above, these
-        settings configure whether and what NTP server information
-        shall be emitted as part of the DHCP lease. The same syntax,
-        propagation semantics and defaults apply as for
-        <varname>EmitDNS=</varname> and
-        <varname>DNS=</varname>.</para></listitem>
-      </varlistentry>
-
-      <varlistentry>
         <term><varname>EmitSIP=</varname></term>
         <term><varname>SIP=</varname></term>
-
-        <listitem><para>Similar to the <varname>EmitDNS=</varname> and
-        <varname>DNS=</varname> settings described above, these
-        settings configure whether and what SIP server information
-        shall be emitted as part of the DHCP lease. The same syntax,
-        propagation semantics and defaults apply as for
-        <varname>EmitDNS=</varname> and
-        <varname>DNS=</varname>.</para></listitem>
-      </varlistentry>
-
-      <varlistentry>
-        <term><varname>POP3Servers=</varname></term>
-
-        <listitem><para>Similar to the <varname>DNS=</varname> setting described above, this setting
-        configures whether and what POP3 server information shall be emitted as part of the DHCP lease. The
-        same syntax, propagation semantics and defaults apply as for
-        <varname>DNS=</varname>.</para></listitem>
-      </varlistentry>
-
-      <varlistentry>
-        <term><varname>SMTPServers=</varname></term>
-
-        <listitem><para>Similar to the <varname>DNS=</varname> setting described above, this
-        setting configures whether and what SMTP server information shall be emitted as part of
-        the DHCP lease. The same syntax, propagation semantics and defaults apply as for
-        <varname>DNS=</varname>.</para></listitem>
-      </varlistentry>
-
-      <varlistentry>
-        <term><varname>LPRServers=</varname></term>
-
-        <listitem><para>Similar to the <varname>DNS=</varname> setting described above, this
-        setting configures whether and what LPR (line printer) server information shall be emitted
-        as part of the DHCP lease. The same syntax, propagation semantics and defaults apply as for
-        <varname>DNS=</varname>.</para></listitem>
+        <term><varname>EmitPOP3=</varname></term>
+        <term><varname>POP3=</varname></term>
+        <term><varname>EmitSMTP=</varname></term>
+        <term><varname>SMTP=</varname></term>
+        <term><varname>EmitLPR=</varname></term>
+        <term><varname>LPR=</varname></term>
+
+        <listitem><para>Similar to the <varname>EmitDNS=</varname> and <varname>DNS=</varname> settings
+        described above, these settings configure whether and what server information for the indicate
+        protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and
+        defaults apply as for <varname>EmitDNS=</varname> and <varname>DNS=</varname>.</para></listitem>
       </varlistentry>
 
       <varlistentry>
diff --git a/src/libsystemd/sd-network/sd-network.c b/src/libsystemd/sd-network/sd-network.c
index 2fde4fbb64..30f47244ad 100644
--- a/src/libsystemd/sd-network/sd-network.c
+++ b/src/libsystemd/sd-network/sd-network.c
@@ -264,22 +264,6 @@ _public_ int sd_network_link_get_route_domains(int ifindex, char ***ret) {
         return network_link_get_strv(ifindex, "ROUTE_DOMAINS", ret);
 }
 
-_public_ int sd_network_link_get_sip_servers(int ifindex, char ***ret) {
-        return network_link_get_strv(ifindex, "SIP", ret);
-}
-
-_public_ int sd_network_link_get_pop3_servers(int ifindex, char ***pop3) {
-        return network_link_get_strv(ifindex, "POP3_SERVERS", pop3);
-}
-
-_public_ int sd_network_link_get_smtp_servers(int ifindex, char ***ret) {
-        return network_link_get_strv(ifindex, "SMTP_SERVERS", ret);
-}
-
-_public_ int sd_network_link_get_lpr_servers(int ifindex, char ***ret) {
-        return network_link_get_strv(ifindex, "LPR_SERVERS", ret);
-}
-
 _public_ int sd_network_link_get_dns_default_route(int ifindex) {
         char path[STRLEN("/run/systemd/netif/links/") + DECIMAL_STR_MAX(ifindex) + 1];
         _cleanup_free_ char *s = NULL;
diff --git a/src/network/networkctl.c b/src/network/networkctl.c
index f7c48f19b1..bf663146d6 100644
--- a/src/network/networkctl.c
+++ b/src/network/networkctl.c
@@ -1378,8 +1378,7 @@ static int link_status_one(
                 sd_hwdb *hwdb,
                 const LinkInfo *info) {
 
-        _cleanup_strv_free_ char **dns = NULL, **ntp = NULL, **sip = NULL, **search_domains = NULL, **route_domains = NULL,
-                **pop3_server = NULL, **smtp_server = NULL, **lpr_server = NULL;
+        _cleanup_strv_free_ char **dns = NULL, **ntp = NULL, **sip = NULL, **search_domains = NULL, **route_domains = NULL;
         _cleanup_free_ char *t = NULL, *network = NULL, *client_id = NULL, *iaid = NULL, *duid = NULL;
         const char *driver = NULL, *path = NULL, *vendor = NULL, *model = NULL, *link = NULL;
         _cleanup_free_ char *setup_state = NULL, *operational_state = NULL, *tz = NULL;
@@ -1406,9 +1405,6 @@ static int link_status_one(
         (void) sd_network_link_get_route_domains(info->ifindex, &route_domains);
         (void) sd_network_link_get_ntp(info->ifindex, &ntp);
         (void) sd_network_link_get_sip(info->ifindex, &sip);
-        (void) sd_network_link_get_pop3_servers(info->ifindex, &pop3_server);
-        (void) sd_network_link_get_smtp_servers(info->ifindex, &smtp_server);
-        (void) sd_network_link_get_lpr_servers(info->ifindex, &lpr_server);
 
         if (info->sd_device) {
                 (void) sd_device_get_property_value(info->sd_device, "ID_NET_LINK_FILE", &link);
@@ -2047,15 +2043,6 @@ static int link_status_one(
         r = dump_list(table, "SIP:", sip);
         if (r < 0)
                 return r;
-        r = dump_list(table, "POP3 servers:", pop3_server);
-        if (r < 0)
-                return r;
-        r = dump_list(table, "SMTP servers:", smtp_server);
-        if (r < 0)
-                return r;
-        r = dump_list(table, "LPR servers:", lpr_server);
-        if (r < 0)
-                return r;
         r = dump_ifindexes(table, "Carrier Bound To:", carrier_bound_to);
         if (r < 0)
                 return r;
diff --git a/src/network/networkd-dhcp-server.c b/src/network/networkd-dhcp-server.c
index 40705c3d81..b3ed4a8cea 100644
--- a/src/network/networkd-dhcp-server.c
+++ b/src/network/networkd-dhcp-server.c
@@ -34,118 +34,95 @@ static Address* link_find_dhcp_server_address(Link *link) {
         return NULL;
 }
 
-static int link_push_uplink_dns_to_dhcp_server(Link *link, sd_dhcp_server *s) {
+static int link_push_uplink_to_dhcp_server(
+                Link *link,
+                sd_dhcp_lease_server_type what,
+                sd_dhcp_server *s) {
+
         _cleanup_free_ struct in_addr *addresses = NULL;
         size_t n_addresses = 0, n_allocated = 0;
+        bool use_dhcp_lease_data = true;
 
-        for (unsigned i = 0; i < link->network->n_dns; i++) {
-                struct in_addr ia;
+        assert(link);
 
-                /* Only look for IPv4 addresses */
-                if (link->network->dns[i].family != AF_INET)
-                        continue;
+        if (!link->network)
+                return 0;
+        assert(link->network);
 
-                ia = link->network->dns[i].address.in;
+        log_link_debug(link, "Copying %s from link", dhcp_lease_server_type_to_string(what));
 
-                /* Never propagate obviously borked data */
-                if (in4_addr_is_null(&ia) || in4_addr_is_localhost(&ia))
-                        continue;
+        switch (what) {
 
-                if (!GREEDY_REALLOC(addresses, n_allocated, n_addresses + 1))
-                        return log_oom();
+        case SD_DHCP_LEASE_DNS:
+                /* For DNS we have a special case. We the data configured explicitly locally along with the
+                 * data from the DHCP lease. */
 
-                addresses[n_addresses++] = ia;
-        }
+                for (unsigned i = 0; i < link->network->n_dns; i++) {
+                        struct in_addr ia;
 
-        if (link->network->dhcp_use_dns && link->dhcp_lease) {
-                const struct in_addr *da;
+                        /* Only look for IPv4 addresses */
+                        if (link->network->dns[i].family != AF_INET)
+                                continue;
 
-                int n = sd_dhcp_lease_get_dns(link->dhcp_lease, &da);
-                if (n > 0) {
-                        if (!GREEDY_REALLOC(addresses, n_allocated, n_addresses + n))
+                        ia = link->network->dns[i].address.in;
+
+                        /* Never propagate obviously borked data */
+                        if (in4_addr_is_null(&ia) || in4_addr_is_localhost(&ia))
+                                continue;
+
+                        if (!GREEDY_REALLOC(addresses, n_allocated, n_addresses + 1))
                                 return log_oom();
 
-                        for (int j = 0; j < n; j++)
-                                if (in4_addr_is_non_local(&da[j]))
-                                        addresses[n_addresses++] = da[j];
+                        addresses[n_addresses++] = ia;
                 }
-        }
 
-        if (n_addresses <= 0)
-                return 0;
+                use_dhcp_lease_data = link->network->dhcp_use_dns;
+                break;
 
-        return sd_dhcp_server_set_dns(s, addresses, n_addresses);
-}
+        case SD_DHCP_LEASE_NTP: {
+                char **i;
 
-static int link_push_uplink_to_dhcp_server(
-                Link *link,
-                sd_dhcp_lease_server_type what,
-                sd_dhcp_server *s) {
-
-        _cleanup_free_ struct in_addr *addresses = NULL;
-        size_t n_addresses = 0, n_allocated = 0;
-        bool lease_condition;
-        char **servers;
+                /* For NTP things are similar, but for NTP hostnames can be configured too, which we cannot
+                 * propagate via DHCP. Hence let's only propagate those which are IP addresses. */
 
-        if (!link->network)
-                return 0;
+                STRV_FOREACH(i, link->network->ntp) {
+                        union in_addr_union ia;
 
-        log_link_debug(link, "Copying %s from link", dhcp_lease_server_type_to_string(what));
+                        if (in_addr_from_string(AF_INET, *i, &ia) < 0)
+                                continue;
 
-        switch (what) {
-        case SD_DHCP_LEASE_DNS:
-                /* DNS servers are stored as parsed data, so special handling is required.
-                 * TODO: check if DNS servers should be stored unparsed too. */
-                return link_push_uplink_dns_to_dhcp_server(link, s);
+                        /* Never propagate obviously borked data */
+                        if (in4_addr_is_null(&ia.in) || in4_addr_is_localhost(&ia.in))
+                                continue;
 
-        case SD_DHCP_LEASE_NTP:
-                servers = link->network->ntp;
-                lease_condition = link->network->dhcp_use_ntp;
-                break;
+                        if (!GREEDY_REALLOC(addresses, n_allocated, n_addresses + 1))
+                                return log_oom();
 
-        case SD_DHCP_LEASE_POP3:
-                servers = link->network->pop3;
-                lease_condition = true;
-                break;
+                        addresses[n_addresses++] = ia.in;
+                }
 
-        case SD_DHCP_LEASE_SMTP:
-                servers = link->network->smtp;
-                lease_condition = true;
+                use_dhcp_lease_data = link->network->dhcp_use_ntp;
                 break;
+        }
 
         case SD_DHCP_LEASE_SIP:
-                servers = link->network->sip;
-                lease_condition = link->network->dhcp_use_sip;
+
+                /* For SIP we don't allow explicit, local configuration, but there's control whether to use the data */
+                use_dhcp_lease_data = link->network->dhcp_use_sip;
                 break;
 
+        case SD_DHCP_LEASE_POP3:
+        case SD_DHCP_LEASE_SMTP:
         case SD_DHCP_LEASE_LPR:
-                servers = link->network->lpr;
-                lease_condition = true;
-                break;
+                /* For the other server types we currently do not allow local configuration of server data,
+                 * since there are typically no local consumers of the data. */
+                ;
 
         default:
-                assert_not_reached("Unknown DHCP lease info item");
-        }
-
-        char **a;
-        STRV_FOREACH(a, servers) {
-                union in_addr_union ia;
-
-                /* Only look for IPv4 addresses */
-                if (in_addr_from_string(AF_INET, *a, &ia) <= 0)
-                        continue;
-
-                /* Never propagate obviously borked data */
-                if (in4_addr_is_null(&ia.in) || in4_addr_is_localhost(&ia.in))
-                        continue;
-
-                if (!GREEDY_REALLOC(addresses, n_allocated, n_addresses + 1))
-                        return log_oom();
-
-                addresses[n_addresses++] = ia.in;
+                assert_not_reached("Unexpected server type");
         }
 
-        if (lease_condition && link->dhcp_lease) {
+        if (use_dhcp_lease_data && link->dhcp_lease) {
                 const struct in_addr *da;
 
                 int n = sd_dhcp_lease_get_servers(link->dhcp_lease, what, &da);
@@ -153,9 +130,9 @@ static int link_push_uplink_to_dhcp_server(
                         if (!GREEDY_REALLOC(addresses, n_allocated, n_addresses + n))
                                 return log_oom();
 
-                        for (int i = 0; i < n; i++)
-                                if (in4_addr_is_non_local(&da[i]))
-                                        addresses[n_addresses++] = da[i];
+                        for (int j = 0; j < n; j++)
+                                if (in4_addr_is_non_local(&da[j]))
+                                        addresses[n_addresses++] = da[j];
                 }
         }
 
@@ -285,71 +262,43 @@ int dhcp4_server_configure(Link *link) {
                         return log_link_error_errno(link, r, "Failed to set default lease time for DHCPv4 server instance: %m");
         }
 
-        const struct {
-                bool condition;
-                const struct in_addr *servers;
-                unsigned n_servers;
-        } configs[] = {
-                [SD_DHCP_LEASE_DNS] = {
-                        link->network->dhcp_server_emit_dns,
-                        link->network->dhcp_server_dns,
-                        link->network->n_dhcp_server_dns,
-                },
-                [SD_DHCP_LEASE_NTP] = {
-                        link->network->dhcp_server_emit_ntp,
-                        link->network->dhcp_server_ntp,
-                        link->network->n_dhcp_server_ntp,
-                },
-                [SD_DHCP_LEASE_SIP] = {
-                        link->network->dhcp_server_emit_sip,
-                        link->network->dhcp_server_sip,
-                        link->network->n_dhcp_server_sip,
-                },
-                [SD_DHCP_LEASE_POP3] = {
-                        true,
-                        link->network->dhcp_server_pop3,
-                        link->network->n_dhcp_server_pop3,
-                },
-                [SD_DHCP_LEASE_SMTP] = {
-                        true,
-                        link->network->dhcp_server_smtp,
-                        link->network->n_dhcp_server_smtp,
-                },
-                [SD_DHCP_LEASE_LPR] = {
-                        true,
-                        link->network->dhcp_server_lpr,
-                        link->network->n_dhcp_server_lpr,
-                },
-        };
-        assert_cc(ELEMENTSOF(configs) == _SD_DHCP_LEASE_SERVER_TYPE_MAX);
-
-        for (unsigned n = 0; n < ELEMENTSOF(configs); n++)
-                if (configs[n].condition) {
-                        if (configs[n].n_servers > 0)
-                                r = sd_dhcp_server_set_servers(link->dhcp_server, n,
-                                                               configs[n].servers, configs[n].n_servers);
+        for (sd_dhcp_lease_server_type type = 0; type < _SD_DHCP_LEASE_SERVER_TYPE_MAX; type ++) {
+
+                if (!link->network->dhcp_server_emit[type].emit)
+                        continue;
+
+                if (link->network->dhcp_server_emit[type].n_addresses > 0)
+                        /* Explicitly specified servers to emit */
+                        r = sd_dhcp_server_set_servers(
+                                        link->dhcp_server,
+                                        type,
+                                        link->network->dhcp_server_emit[type].addresses,
+                                        link->network->dhcp_server_emit[type].n_addresses);
+                else {
+                        /* Emission is requested, but nothing explicitly configured. Let's find a suitable upling */
+                        if (!acquired_uplink) {
+                                uplink = manager_find_uplink(link->manager, link);
+                                acquired_uplink = true;
+                        }
+
+                        if (uplink && uplink->network)
+                                r = link_push_uplink_to_dhcp_server(uplink, type, link->dhcp_server);
+                        else if (type == SD_DHCP_LEASE_DNS)
+                                r = dhcp4_server_set_dns_from_resolve_conf(link);
                         else {
-                                if (!acquired_uplink) {
-                                        uplink = manager_find_uplink(link->manager, link);
-                                        acquired_uplink = true;
-                                }
-
-                                if (!uplink) {
-                                        log_link_debug(link,
-                                                       "Not emitting %s on link, couldn't find suitable uplink.",
-                                                       dhcp_lease_server_type_to_string(n));
-                                        r = 0;
-                                } else if (uplink->network)
-                                        r = link_push_uplink_to_dhcp_server(uplink, n, link->dhcp_server);
-                                else if (n == SD_DHCP_LEASE_DNS)
-                                        r = dhcp4_server_set_dns_from_resolve_conf(link);
+                                log_link_debug(link,
+                                               "Not emitting %s on link, couldn't find suitable uplink.",
+                                               dhcp_lease_server_type_to_string(type));
+                                continue;
                         }
-                        if (r < 0)
-                                log_link_warning_errno(link, r,
-                                                       "Failed to set %s for DHCP server, ignoring: %m",
-                                                       dhcp_lease_server_type_to_string(n));
                 }
 
+                if (r < 0)
+                        log_link_warning_errno(link, r,
+                                               "Failed to set %s for DHCP server, ignoring: %m",
+                                               dhcp_lease_server_type_to_string(type));
+        }
+
         r = sd_dhcp_server_set_emit_router(link->dhcp_server, link->network->dhcp_server_emit_router);
         if (r < 0)
                 return log_link_error_errno(link, r, "Failed to set router emission for DHCP server: %m");
@@ -398,17 +347,21 @@ int dhcp4_server_configure(Link *link) {
         return 0;
 }
 
-static int config_parse_dhcp_lease_server_list(
+int config_parse_dhcp_server_emit(
                 const char *unit,
                 const char *filename,
                 unsigned line,
+                const char *section,
+                unsigned section_line,
                 const char *lvalue,
+                int ltype,
                 const char *rvalue,
-                struct in_addr **addresses,
-                unsigned *n_addresses) {
+                void *data,
+                void *userdata) {
 
-        assert(filename);
-        assert(lvalue);
+        NetworkDHCPServerEmitAddress *emit = data;
+
+        assert(emit);
         assert(rvalue);
 
         for (const char *p = rvalue;;) {
@@ -434,127 +387,11 @@ static int config_parse_dhcp_lease_server_list(
                         continue;
                 }
 
-                struct in_addr *m = reallocarray(*addresses, *n_addresses + 1, sizeof(struct in_addr));
+                struct in_addr *m = reallocarray(emit->addresses, emit->n_addresses + 1, sizeof(struct in_addr));
                 if (!m)
                         return log_oom();
 
-                m[(*n_addresses)++] = a.in;
-                *addresses = m;
+                emit->addresses = m;
+                emit->addresses[emit->n_addresses++] = a.in;
         }
 }
-
-int config_parse_dhcp_server_dns(
-                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 *n = data;
-
-        return config_parse_dhcp_lease_server_list(unit, filename, line,
-                                                   lvalue, rvalue,
-                                                   &n->dhcp_server_dns, &n->n_dhcp_server_dns);
-}
-
-int config_parse_dhcp_server_ntp(
-                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 *n = data;
-
-        return config_parse_dhcp_lease_server_list(unit, filename, line,
-                                                   lvalue, rvalue,
-                                                   &n->dhcp_server_ntp, &n->n_dhcp_server_ntp);
-}
-
-int config_parse_dhcp_server_sip(
-                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 *n = data;
-
-        return config_parse_dhcp_lease_server_list(unit, filename, line,
-                                                   lvalue, rvalue,
-                                                   &n->dhcp_server_sip, &n->n_dhcp_server_sip);
-}
-
-int config_parse_dhcp_server_pop3_servers(
-                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 *n = data;
-
-        return config_parse_dhcp_lease_server_list(unit, filename, line,
-                                                   lvalue, rvalue,
-                                                   &n->dhcp_server_pop3, &n->n_dhcp_server_pop3);
-}
-
-int config_parse_dhcp_server_smtp_servers(
-                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 *n = data;
-
-        return config_parse_dhcp_lease_server_list(unit, filename, line,
-                                                   lvalue, rvalue,
-                                                   &n->dhcp_server_smtp, &n->n_dhcp_server_smtp);
-
-}
-
-int config_parse_dhcp_server_lpr_servers(
-                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 *n = data;
-
-        return config_parse_dhcp_lease_server_list(unit, filename, line,
-                                                   lvalue, rvalue,
-                                                   &n->dhcp_server_lpr, &n->n_dhcp_server_lpr);
-
-}
diff --git a/src/network/networkd-dhcp-server.h b/src/network/networkd-dhcp-server.h
index 898e9acd52..2250a30af4 100644
--- a/src/network/networkd-dhcp-server.h
+++ b/src/network/networkd-dhcp-server.h
@@ -9,9 +9,4 @@ typedef struct Link Link;
 
 int dhcp4_server_configure(Link *link);
 
-CONFIG_PARSER_PROTOTYPE(config_parse_dhcp_server_dns);
-CONFIG_PARSER_PROTOTYPE(config_parse_dhcp_server_ntp);
-CONFIG_PARSER_PROTOTYPE(config_parse_dhcp_server_sip);
-CONFIG_PARSER_PROTOTYPE(config_parse_dhcp_server_pop3_servers);
-CONFIG_PARSER_PROTOTYPE(config_parse_dhcp_server_smtp_servers);
-CONFIG_PARSER_PROTOTYPE(config_parse_dhcp_server_lpr_servers);
+CONFIG_PARSER_PROTOTYPE(config_parse_dhcp_server_emit);
diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index be5c58087e..afeb36d315 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -4196,32 +4196,11 @@ int link_save(Link *link) {
                                     sd_dhcp6_lease_get_ntp_fqdn);
 
                 serialize_addresses(f, "SIP", NULL,
-                                    link->network->sip,
+                                    NULL,
                                     link->dhcp_lease,
                                     link->network->dhcp_use_sip,
                                     SD_DHCP_LEASE_SIP,
-                                    false, NULL, NULL, NULL);
-
-                serialize_addresses(f, "POP3", NULL,
-                                    link->network->pop3,
-                                    link->dhcp_lease,
-                                    true,
-                                    SD_DHCP_LEASE_POP3,
-                                    false, NULL, NULL, NULL);
-
-                serialize_addresses(f, "SMTP", NULL,
-                                    link->network->smtp,
-                                    link->dhcp_lease,
-                                    true,
-                                    SD_DHCP_LEASE_SMTP,
-                                    false, NULL, NULL, NULL);
-
-                serialize_addresses(f, "LPR", NULL,
-                                    link->network->lpr,
-                                    link->dhcp_lease,
-                                    true,
-                                    SD_DHCP_LEASE_LPR,
-                                    false, NULL, NULL, NULL);
+                                    NULL, false, NULL, NULL);
 
                 /************************************************************/
 
diff --git a/src/network/networkd-link.h b/src/network/networkd-link.h
index b1a8c432aa..2d36ed2463 100644
--- a/src/network/networkd-link.h
+++ b/src/network/networkd-link.h
@@ -159,7 +159,7 @@ typedef struct Link {
         struct rtnl_link_stats64 stats_old, stats_new;
         bool stats_updated;
 
-        /* All kinds of DNS configuration */
+        /* All kinds of DNS configuration the user configured via D-Bus */
         struct in_addr_data *dns;
         unsigned n_dns;
         OrderedSet *search_domains, *route_domains;
@@ -171,6 +171,7 @@ typedef struct Link {
         DnsOverTlsMode dns_over_tls_mode;
         Set *dnssec_negative_trust_anchors;
 
+        /* Similar, but NTP server configuration */
         char **ntp;
 } Link;
 
diff --git a/src/network/networkd-manager.c b/src/network/networkd-manager.c
index abfdf7ff74..8692b9411e 100644
--- a/src/network/networkd-manager.c
+++ b/src/network/networkd-manager.c
@@ -1499,8 +1499,7 @@ static int ordered_set_put_in4_addrv(OrderedSet *s,
 }
 
 static int manager_save(Manager *m) {
-        _cleanup_ordered_set_free_free_ OrderedSet *dns = NULL, *ntp = NULL, *sip = NULL, *pop3 = NULL,
-                *smtp = NULL, *lpr = NULL, *search_domains = NULL, *route_domains = NULL;
+        _cleanup_ordered_set_free_free_ OrderedSet *dns = NULL, *ntp = NULL, *sip = NULL, *search_domains = NULL, *route_domains = NULL;
         const char *operstate_str, *carrier_state_str, *address_state_str;
         LinkOperationalState operstate = LINK_OPERSTATE_OFF;
         LinkCarrierState carrier_state = LINK_CARRIER_STATE_OFF;
@@ -1508,7 +1507,6 @@ static int manager_save(Manager *m) {
         _cleanup_free_ char *temp_path = NULL;
         _cleanup_strv_free_ char **p = NULL;
         _cleanup_fclose_ FILE *f = NULL;
-        const struct in_addr *addresses;
         Link *link;
         Iterator i;
         int r;
@@ -1529,18 +1527,6 @@ static int manager_save(Manager *m) {
         if (!sip)
                 return -ENOMEM;
 
-        pop3 = ordered_set_new(&string_hash_ops);
-        if (!pop3)
-                return -ENOMEM;
-
-        smtp = ordered_set_new(&string_hash_ops);
-        if (!smtp)
-                return -ENOMEM;
-
-        lpr = ordered_set_new(&string_hash_ops);
-        if (!lpr)
-                return -ENOMEM;
-
         search_domains = ordered_set_new(&dns_name_hash_ops);
         if (!search_domains)
                 return -ENOMEM;
@@ -1550,6 +1536,8 @@ static int manager_save(Manager *m) {
                 return -ENOMEM;
 
         HASHMAP_FOREACH(link, m->links, i) {
+                const struct in_addr *addresses;
+
                 if (link->flags & IFF_LOOPBACK)
                         continue;
 
@@ -1616,30 +1604,6 @@ static int manager_save(Manager *m) {
                                 return r;
                 }
 
-                r = sd_dhcp_lease_get_pop3(link->dhcp_lease, &addresses);
-                if (r > 0) {
-                        r = ordered_set_put_in4_addrv(pop3, addresses, r, in4_addr_is_non_local);
-                        if (r < 0)
-                                return r;
-                } else if (r < 0 && r != -ENODATA)
-                        return r;
-
-                r = sd_dhcp_lease_get_smtp(link->dhcp_lease, &addresses);
-                if (r > 0) {
-                        r = ordered_set_put_in4_addrv(smtp, addresses, r, in4_addr_is_non_local);
-                        if (r < 0)
-                                return r;
-                } else if (r < 0 && r != -ENODATA)
-                        return r;
-
-                r = sd_dhcp_lease_get_lpr(link->dhcp_lease, &addresses);
-                if (r > 0) {
-                        r = ordered_set_put_in4_addrv(lpr, addresses, r, in4_addr_is_non_local);
-                        if (r < 0)
-                                return r;
-                } else if (r < 0 && r != -ENODATA)
-                        return r;
-
                 if (link->network->dhcp_use_domains != DHCP_USE_DOMAINS_NO) {
                         const char *domainname;
                         char **domains = NULL;
@@ -1691,9 +1655,6 @@ static int manager_save(Manager *m) {
         ordered_set_print(f, "DNS=", dns);
         ordered_set_print(f, "NTP=", ntp);
         ordered_set_print(f, "SIP=", sip);
-        ordered_set_print(f, "POP3_SERVERS=", pop3);
-        ordered_set_print(f, "SMTP_SERVERS=", smtp);
-        ordered_set_print(f, "LPR_SERVERS=", lpr);
         ordered_set_print(f, "DOMAINS=", search_domains);
         ordered_set_print(f, "ROUTE_DOMAINS=", route_domains);
 
diff --git a/src/network/networkd-network-gperf.gperf b/src/network/networkd-network-gperf.gperf
index 84ea5d552e..fc756ef0fc 100644
--- a/src/network/networkd-network-gperf.gperf
+++ b/src/network/networkd-network-gperf.gperf
@@ -217,15 +217,18 @@ IPv6AcceptRA.RouteTable,                     config_parse_section_route_table,
 IPv6AcceptRA.BlackList,                      config_parse_ndisc_black_listed_prefix,                   0,                             0
 DHCPServer.MaxLeaseTimeSec,                  config_parse_sec,                                         0,                             offsetof(Network, dhcp_server_max_lease_time_usec)
 DHCPServer.DefaultLeaseTimeSec,              config_parse_sec,                                         0,                             offsetof(Network, dhcp_server_default_lease_time_usec)
-DHCPServer.EmitDNS,                          config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_emit_dns)
-DHCPServer.DNS,                              config_parse_dhcp_server_dns,                             0,                             0
-DHCPServer.EmitNTP,                          config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_emit_ntp)
-DHCPServer.NTP,                              config_parse_dhcp_server_ntp,                             0,                             0
-DHCPServer.EmitSIP,                          config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_emit_sip)
-DHCPServer.SIP,                              config_parse_dhcp_server_sip,                             0,                             0
-DHCPServer.POP3Servers,                      config_parse_dhcp_server_pop3_servers,                    0,                             0
-DHCPServer.SMTPServers,                      config_parse_dhcp_server_smtp_servers,                    0,                             0
-DHCPServer.LPRServers,                       config_parse_dhcp_server_lpr_servers,                     0,                             0
+DHCPServer.EmitDNS,                          config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_DNS].emit)
+DHCPServer.DNS,                              config_parse_dhcp_server_emit,                            0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_DNS])
+DHCPServer.EmitNTP,                          config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_NTP].emit)
+DHCPServer.NTP,                              config_parse_dhcp_server_emit,                            0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_NTP])
+DHCPServer.EmitSIP,                          config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_SIP].emit)
+DHCPServer.SIP,                              config_parse_dhcp_server_emit,                            0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_SIP])
+DHCPServer.EmitPOP3,                         config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_POP3].emit)
+DHCPServer.POP3,                             config_parse_dhcp_server_emit,                            0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_POP3])
+DHCPServer.EmitSMTP,                         config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_SMTP].emit)
+DHCPServer.SMTP,                             config_parse_dhcp_server_emit,                            0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_SMTP])
+DHCPServer.EmitLPR,                          config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_LPR].emit)
+DHCPServer.LPR,                              config_parse_dhcp_server_emit,                            0,                             offsetof(Network, dhcp_server_emit[SD_DHCP_LEASE_LPR])
 DHCPServer.EmitRouter,                       config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_emit_router)
 DHCPServer.EmitTimezone,                     config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_emit_timezone)
 DHCPServer.Timezone,                         config_parse_timezone,                                    0,                             offsetof(Network, dhcp_server_timezone)
diff --git a/src/network/networkd-network.c b/src/network/networkd-network.c
index 51c57af563..f0fa5d0427 100644
--- a/src/network/networkd-network.c
+++ b/src/network/networkd-network.c
@@ -416,9 +416,10 @@ int network_load_one(Manager *manager, OrderedHashmap **networks, const char *fi
 
                 .dhcp6_pd_assign_prefix = true,
 
-                .dhcp_server_emit_dns = true,
-                .dhcp_server_emit_ntp = true,
-                .dhcp_server_emit_sip = true,
+                .dhcp_server_emit[SD_DHCP_LEASE_DNS].emit = true,
+                .dhcp_server_emit[SD_DHCP_LEASE_NTP].emit = true,
+                .dhcp_server_emit[SD_DHCP_LEASE_SIP].emit = true,
+
                 .dhcp_server_emit_router = true,
                 .dhcp_server_emit_timezone = true,
 
@@ -673,8 +674,6 @@ static Network *network_free(Network *network) {
 
         strv_free(network->ntp);
         free(network->dns);
-        strv_free(network->sip);
-        strv_free(network->smtp);
         ordered_set_free_free(network->search_domains);
         ordered_set_free_free(network->route_domains);
         strv_free(network->bind_carrier);
@@ -740,12 +739,9 @@ static Network *network_free(Network *network) {
         free(network->name);
 
         free(network->dhcp_server_timezone);
-        free(network->dhcp_server_dns);
-        free(network->dhcp_server_ntp);
-        free(network->dhcp_server_sip);
-        free(network->dhcp_server_pop3);
-        free(network->dhcp_server_smtp);
-        free(network->dhcp_server_lpr);
+
+        for (sd_dhcp_lease_server_type t = 0; t < _SD_DHCP_LEASE_SERVER_TYPE_MAX; t++)
+                free(network->dhcp_server_emit[t].addresses);
 
         set_free_free(network->dnssec_negative_trust_anchors);
 
diff --git a/src/network/networkd-network.h b/src/network/networkd-network.h
index 00ecac6ca9..a2fcc5209b 100644
--- a/src/network/networkd-network.h
+++ b/src/network/networkd-network.h
@@ -54,6 +54,12 @@ typedef enum KeepConfiguration {
 
 typedef struct Manager Manager;
 
+typedef struct NetworkDHCPServerEmitAddress {
+        bool emit;
+        struct in_addr *addresses;
+        size_t n_addresses;
+} NetworkDHCPServerEmitAddress;
+
 struct Network {
         Manager *manager;
 
@@ -149,28 +155,7 @@ struct Network {
 
         /* DHCP Server Support */
         bool dhcp_server;
-
-        bool dhcp_server_emit_dns;
-        struct in_addr *dhcp_server_dns;
-        unsigned n_dhcp_server_dns;
-
-        bool dhcp_server_emit_ntp;
-        struct in_addr *dhcp_server_ntp;
-        unsigned n_dhcp_server_ntp;
-
-        bool dhcp_server_emit_sip;
-        struct in_addr *dhcp_server_sip;
-        unsigned n_dhcp_server_sip;
-
-        struct in_addr *dhcp_server_pop3;
-        unsigned n_dhcp_server_pop3;
-
-        struct in_addr *dhcp_server_smtp;
-        unsigned n_dhcp_server_smtp;
-
-        struct in_addr *dhcp_server_lpr;
-        unsigned n_dhcp_server_lpr;
-
+        NetworkDHCPServerEmitAddress dhcp_server_emit[_SD_DHCP_LEASE_SERVER_TYPE_MAX];
         bool dhcp_server_emit_router;
         bool dhcp_server_emit_timezone;
         char *dhcp_server_timezone;
@@ -331,10 +316,6 @@ struct Network {
         Set *dnssec_negative_trust_anchors;
 
         char **ntp;
-        char **sip;
-        char **pop3;
-        char **smtp;
-        char **lpr;
         char **bind_carrier;
 };
 
diff --git a/src/systemd/sd-dhcp-server.h b/src/systemd/sd-dhcp-server.h
index 2e15a6b181..b6a5e9db84 100644
--- a/src/systemd/sd-dhcp-server.h
+++ b/src/systemd/sd-dhcp-server.h
@@ -68,8 +68,8 @@ int sd_dhcp_server_set_lpr(sd_dhcp_server *server, const struct in_addr lpr[], s
 int sd_dhcp_server_set_dns(sd_dhcp_server *server, const struct in_addr dns[], size_t n);
 int sd_dhcp_server_set_ntp(sd_dhcp_server *server, const struct in_addr ntp[], size_t n);
 int sd_dhcp_server_set_sip(sd_dhcp_server *server, const struct in_addr sip[], size_t n);
-int sd_dhcp_server_set_pop3(sd_dhcp_server *server, const struct in_addr pop3_server[], size_t n);
-int sd_dhcp_server_set_smtp(sd_dhcp_server *server, const struct in_addr smtp_server[], size_t n);
+int sd_dhcp_server_set_pop3(sd_dhcp_server *server, const struct in_addr pop3[], size_t n);
+int sd_dhcp_server_set_smtp(sd_dhcp_server *server, const struct in_addr smtp[], size_t n);
 
 int sd_dhcp_server_add_option(sd_dhcp_server *server, sd_dhcp_option *v);
 int sd_dhcp_server_add_vendor_option(sd_dhcp_server *server, sd_dhcp_option *v);
diff --git a/src/systemd/sd-network.h b/src/systemd/sd-network.h
index 7e42df17b9..edb40850b1 100644
--- a/src/systemd/sd-network.h
+++ b/src/systemd/sd-network.h
@@ -164,18 +164,6 @@ int sd_network_link_get_search_domains(int ifindex, char ***domains);
 /* Get the route DNS domain names for a given link. */
 int sd_network_link_get_route_domains(int ifindex, char ***domains);
 
-/* Get the sip servers for a given link. */
-int sd_network_link_get_sip_servers(int ifindex, char ***sip);
-
-/* Get the pop3 servers for a given link. */
-int sd_network_link_get_pop3_servers(int ifindex, char ***pop3);
-
-/* Get the SMTP servers for a given link. */
-int sd_network_link_get_smtp_servers(int ifindex, char ***smtp);
-
-/* Get the LPR servers for a given link. */
-int sd_network_link_get_lpr_servers(int ifindex, char ***lpr);
-
 /* Get whether this link shall be used as 'default route' for DNS queries */
 int sd_network_link_get_dns_default_route(int ifindex);
 
diff --git a/test/fuzz/fuzz-network-parser/directives.network b/test/fuzz/fuzz-network-parser/directives.network
index a6ef817360..f97b1ba1b8 100644
--- a/test/fuzz/fuzz-network-parser/directives.network
+++ b/test/fuzz/fuzz-network-parser/directives.network
@@ -289,9 +289,12 @@ EmitDNS=
 NTP=
 EmitSIP=
 SIP=
-POP3Servers=
-SMTPServers=
-LPRServers=
+EmitPOP3=
+POP3=
+EmitSMTP=
+SMTP=
+EmitLPR=
+LPR=
 EmitRouter=
 MaxLeaseTimeSec=
 DefaultLeaseTimeSec=