Merge pull request #21129 from yuwata/network-dhcp6-pd-vs-ndisc

network: several follow-ups for DHCPv6-PD

7 files changed, 71 insertions, 59 deletions

diff --git a/man/systemd.network.xml b/man/systemd.network.xml
index b6bf993adc..41a58b36eb 100644
--- a/man/systemd.network.xml
+++ b/man/systemd.network.xml
@@ -2090,27 +2090,15 @@ Table=1234</programlisting></para>
         <!-- How to communicate with the server -->
 
         <varlistentry>
-          <term><varname>ForceDHCPv6PDOtherInformation=</varname></term>
-          <listitem>
-            <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
-            Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
-            makes DHCPv6 request network information in a stateless manner using a two-message Information
-            Request and Information Reply message exchange.
-            <ulink url="https://tools.ietf.org/html/rfc7084">RFC 7084</ulink>, requirement WPD-4, updates
-            this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
-            requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
-            behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
-            By default this option is set to false, enable it if no prefixes are delegated when the device
-            should be acting as a CE router.</para>
-          </listitem>
-        </varlistentry>
-
-        <varlistentry>
           <term><varname>WithoutRA=</varname></term>
           <listitem>
-            <para>Allows DHCPv6 client to start without router advertisements's managed or other address
-            configuration flag. Takes one of <literal>solicit</literal> or
-            <literal>information-request</literal>. Defaults to unset.</para>
+            <para>Allows DHCPv6 client to start without router advertisements's managed or other
+            address configuration flag. Takes one of <literal>no</literal>, <literal>solicit</literal>
+            or <literal>information-request</literal>. When this is not specified and
+            <varname>UplinkInterface=:self</varname> is specified, then <literal>solicit</literal> is
+            implied. Otherwise, defaults to <literal>no</literal>, and the DHCPv6 client will be
+            started when an RA is received. See also <varname>DHCPv6Client=</varname> setting in the
+            [IPv6AcceptRA] section.</para>
           </listitem>
         </varlistentry>
       </variablelist>
@@ -2128,9 +2116,10 @@ Table=1234</programlisting></para>
         <listitem>
           <para>Specifies the name or the index of the uplink interface, or one of the special values
           <literal>:self</literal> and <literal>:auto</literal>. When <literal>:self</literal>, the
-          interface itself is considered the uplink interface. When <literal>:auto</literal>, the first
-          link which acquired prefixes to be delegated from the DHCPv6 server is selected. Defaults to
-          <literal>:auto</literal>.</para>
+          interface itself is considered the uplink interface, and
+          <varname>WithoutRA=solicit</varname> is implied if the setting is not explicitly specified.
+          When <literal>:auto</literal>, the first link which acquired prefixes to be delegated from
+          the DHCPv6 server is selected. Defaults to <literal>:auto</literal>.</para>
         </listitem>
       </varlistentry>
 
@@ -2382,11 +2371,13 @@ Token=prefixstable:2002:da8:1::</programlisting></para>
         <varlistentry>
           <term><varname>DHCPv6Client=</varname></term>
           <listitem>
-            <para>Takes a boolean, or the special value <literal>always</literal>. When true or
-            <literal>always</literal>, the DHCPv6 client will be started when the RA has the managed or
-            other information flag. If set to <literal>always</literal>, the DHCPv6 client will also be
-            started in managed mode when neither managed nor other information flag is set in the RA.
-            Defaults to true.</para>
+            <para>Takes a boolean, or the special value <literal>always</literal>. When true, the
+            DHCPv6 client will be started when the RA has the managed or other information flag. If set
+            to <literal>always</literal>, the DHCPv6 client will be started in managed mode when an RA
+            is received, even if neither managed nor other information flag is set in the RA. This will
+            be ignored when <varname>WithoutRA=</varname> in the [DHCPv6] section is enabled, or
+            <varname>UplinkInterface=:self</varname> in the [DHCPv6PrefixDelegation] section is
+            specified. Defaults to true.</para>
           </listitem>
         </varlistentry>
       </variablelist>
diff --git a/src/network/networkd-dhcp6.c b/src/network/networkd-dhcp6.c
index 52ff5eb3aa..3cc457a02d 100644
--- a/src/network/networkd-dhcp6.c
+++ b/src/network/networkd-dhcp6.c
@@ -58,6 +58,25 @@ static int dhcp6_pd_resolve_uplink(Link *link, Link **ret) {
         return -ENOENT;
 }
 
+static DHCP6ClientStartMode link_get_dhcp6_client_start_mode(Link *link) {
+        Link *uplink;
+
+        assert(link);
+
+        if (!link->network)
+                return DHCP6_CLIENT_START_MODE_NO;
+
+        /* When WithoutRA= is explicitly specified, then honor it. */
+        if (link->network->dhcp6_client_start_mode >= 0)
+                return link->network->dhcp6_client_start_mode;
+
+        if (dhcp6_pd_resolve_uplink(link, &uplink) < 0)
+                return DHCP6_CLIENT_START_MODE_NO;
+
+        /* When this interface itself is an uplink interface, then start dhcp6 client in managed mode */
+        return uplink == link ? DHCP6_CLIENT_START_MODE_SOLICIT : DHCP6_CLIENT_START_MODE_NO;
+}
+
 static bool dhcp6_lease_has_pd_prefix(sd_dhcp6_lease *lease) {
         uint32_t lifetime_preferred_sec, lifetime_valid_sec;
         struct in6_addr pd_prefix;
@@ -1311,40 +1330,31 @@ static void dhcp6_handler(sd_dhcp6_client *client, int event, void *userdata) {
         }
 }
 
-int dhcp6_request_information(Link *link, int ir) {
-        int r, inf_req, pd;
-        bool running;
+int dhcp6_start_on_ra(Link *link, bool information_request) {
+        int r;
 
         assert(link);
         assert(link->dhcp6_client);
         assert(link->network);
         assert(in6_addr_is_link_local(&link->ipv6ll_address));
 
-        r = sd_dhcp6_client_is_running(link->dhcp6_client);
-        if (r < 0)
-                return r;
-        running = r;
+        if (link_get_dhcp6_client_start_mode(link) != DHCP6_CLIENT_START_MODE_NO)
+                /* When WithoutRA= is specified, then the DHCPv6 client should be already runnging in
+                 * the requested mode. Hence, ignore the requests by RA. */
+                return 0;
 
-        r = sd_dhcp6_client_get_prefix_delegation(link->dhcp6_client, &pd);
+        r = sd_dhcp6_client_is_running(link->dhcp6_client);
         if (r < 0)
                 return r;
 
-        if (pd && ir && link->network->dhcp6_force_pd_other_information) {
-                log_link_debug(link, "Enabling managed mode to request DHCPv6 PD with 'Other Information' set");
+        if (r > 0) {
+                int inf_req;
 
-                r = sd_dhcp6_client_set_address_request(link->dhcp6_client, false);
-                if (r < 0)
-                        return r;
-
-                ir = false;
-        }
-
-        if (running) {
                 r = sd_dhcp6_client_get_information_request(link->dhcp6_client, &inf_req);
                 if (r < 0)
                         return r;
 
-                if (inf_req == ir)
+                if (inf_req == information_request)
                         return 0;
 
                 r = sd_dhcp6_client_stop(link->dhcp6_client);
@@ -1356,7 +1366,7 @@ int dhcp6_request_information(Link *link, int ir) {
                         return r;
         }
 
-        r = sd_dhcp6_client_set_information_request(link->dhcp6_client, ir);
+        r = sd_dhcp6_client_set_information_request(link->dhcp6_client, information_request);
         if (r < 0)
                 return r;
 
@@ -1368,9 +1378,11 @@ int dhcp6_request_information(Link *link, int ir) {
 }
 
 int dhcp6_start(Link *link) {
+        DHCP6ClientStartMode start_mode;
         int r;
 
         assert(link);
+        assert(link->network);
 
         if (!link->dhcp6_client)
                 return 0;
@@ -1381,7 +1393,7 @@ int dhcp6_start(Link *link) {
         if (!link_has_carrier(link))
                 return 0;
 
-        if (link->network->dhcp6_without_ra == DHCP6_CLIENT_START_MODE_NO)
+        if (sd_dhcp6_client_is_running(link->dhcp6_client) > 0)
                 return 0;
 
         if (!in6_addr_is_link_local(&link->ipv6ll_address)) {
@@ -1389,10 +1401,20 @@ int dhcp6_start(Link *link) {
                 return 0;
         }
 
-        if (sd_dhcp6_client_is_running(link->dhcp6_client) > 0)
+        r = sd_dhcp6_client_set_local_address(link->dhcp6_client, &link->ipv6ll_address);
+        if (r < 0)
+                return r;
+
+        start_mode = link_get_dhcp6_client_start_mode(link);
+        if (start_mode == DHCP6_CLIENT_START_MODE_NO)
                 return 0;
 
-        r = dhcp6_request_information(link, link->network->dhcp6_without_ra == DHCP6_CLIENT_START_MODE_INFORMATION_REQUEST);
+        r = sd_dhcp6_client_set_information_request(link->dhcp6_client,
+                                                    start_mode == DHCP6_CLIENT_START_MODE_INFORMATION_REQUEST);
+        if (r < 0)
+                return r;
+
+        r = sd_dhcp6_client_start(link->dhcp6_client);
         if (r < 0)
                 return r;
 
diff --git a/src/network/networkd-dhcp6.h b/src/network/networkd-dhcp6.h
index a08d03b614..4a522aebcf 100644
--- a/src/network/networkd-dhcp6.h
+++ b/src/network/networkd-dhcp6.h
@@ -21,7 +21,7 @@ bool link_dhcp6_pd_is_enabled(Link *link);
 int dhcp6_pd_remove(Link *link, bool only_marked);
 int dhcp6_update_mac(Link *link);
 int dhcp6_start(Link *link);
-int dhcp6_request_information(Link *link, int ir);
+int dhcp6_start_on_ra(Link *link, bool information_request);
 int dhcp6_request_prefix_delegation(Link *link);
 
 int request_process_dhcp6_client(Request *req);
diff --git a/src/network/networkd-ndisc.c b/src/network/networkd-ndisc.c
index d7b79f7416..5f831b58a4 100644
--- a/src/network/networkd-ndisc.c
+++ b/src/network/networkd-ndisc.c
@@ -906,13 +906,13 @@ static int ndisc_start_dhcp6_client(Link *link, sd_ndisc_router *rt) {
                 /* (re)start DHCPv6 client in stateful or stateless mode according to RA flags.
                  * Note, if both managed and other information bits are set, then ignore other
                  * information bit. See RFC 4861. */
-                r = dhcp6_request_information(link, !(flags & ND_RA_FLAG_MANAGED));
+                r = dhcp6_start_on_ra(link, !(flags & ND_RA_FLAG_MANAGED));
                 break;
         }
         case IPV6_ACCEPT_RA_START_DHCP6_CLIENT_ALWAYS:
                 /* When IPv6AcceptRA.DHCPv6Client=always, start dhcp6 client in managed mode
                  * even if the router flags have neither M nor O flags. */
-                r = dhcp6_request_information(link, false);
+                r = dhcp6_start_on_ra(link, /* information_request = */ false);
                 break;
 
         default:
diff --git a/src/network/networkd-network-gperf.gperf b/src/network/networkd-network-gperf.gperf
index ccbf02b99d..6631f5bc3e 100644
--- a/src/network/networkd-network-gperf.gperf
+++ b/src/network/networkd-network-gperf.gperf
@@ -248,9 +248,8 @@ DHCPv6.RequestOptions,                       config_parse_dhcp_request_options,
 DHCPv6.UserClass,                            config_parse_dhcp_user_or_vendor_class,                   AF_INET6,                      offsetof(Network, dhcp6_user_class)
 DHCPv6.VendorClass,                          config_parse_dhcp_user_or_vendor_class,                   AF_INET6,                      offsetof(Network, dhcp6_vendor_class)
 DHCPv6.SendVendorOption,                     config_parse_dhcp_send_option,                            AF_INET6,                      offsetof(Network, dhcp6_client_send_vendor_options)
-DHCPv6.ForceDHCPv6PDOtherInformation,        config_parse_bool,                                        0,                             offsetof(Network, dhcp6_force_pd_other_information)
 DHCPv6.PrefixDelegationHint,                 config_parse_dhcp6_pd_prefix_hint,                        0,                             0
-DHCPv6.WithoutRA,                            config_parse_dhcp6_client_start_mode,                     0,                             offsetof(Network, dhcp6_without_ra)
+DHCPv6.WithoutRA,                            config_parse_dhcp6_client_start_mode,                     0,                             offsetof(Network, dhcp6_client_start_mode)
 DHCPv6.SendOption,                           config_parse_dhcp_send_option,                            AF_INET6,                      offsetof(Network, dhcp6_client_send_options)
 DHCPv6.IAID,                                 config_parse_iaid,                                        AF_INET6,                      0
 DHCPv6.DUIDType,                             config_parse_duid_type,                                   0,                             offsetof(Network, dhcp6_duid)
@@ -530,11 +529,12 @@ DHCP.RouteTable,                             config_parse_dhcp_or_ra_route_table
 DHCP.UseTimezone,                            config_parse_bool,                                        0,                             offsetof(Network, dhcp_use_timezone)
 DHCP.ListenPort,                             config_parse_uint16,                                      0,                             offsetof(Network, dhcp_client_port)
 DHCP.RapidCommit,                            config_parse_warn_compat,                                 DISABLED_LEGACY,               0
-DHCP.ForceDHCPv6PDOtherInformation,          config_parse_bool,                                        0,                             offsetof(Network, dhcp6_force_pd_other_information)
+DHCP.ForceDHCPv6PDOtherInformation,          config_parse_warn_compat,                                 DISABLED_LEGACY,               0
 DHCPv4.UseDomainName,                        config_parse_dhcp_use_domains,                            AF_INET,                       0
 DHCPv4.CriticalConnection,                   config_parse_tristate,                                    0,                             offsetof(Network, dhcp_critical)
 DHCPv6.RouteMetric,                          config_parse_dhcp_or_ra_route_metric,                     AF_INET6,                      0
 DHCPv6.RapidCommit,                          config_parse_warn_compat,                                 DISABLED_LEGACY,               0
+DHCPv6.ForceDHCPv6PDOtherInformation,        config_parse_warn_compat,                                 DISABLED_LEGACY,               0
 IPv6AcceptRA.DenyList,                       config_parse_in_addr_prefixes,                            AF_INET6,                      offsetof(Network, ndisc_deny_listed_prefix)
 IPv6AcceptRA.BlackList,                      config_parse_in_addr_prefixes,                            AF_INET6,                      offsetof(Network, ndisc_deny_listed_prefix)
 TrafficControlQueueingDiscipline.Parent,                        config_parse_qdisc_parent,             _QDISC_KIND_INVALID,           0
diff --git a/src/network/networkd-network.c b/src/network/networkd-network.c
index c3c792eb49..5469cb4560 100644
--- a/src/network/networkd-network.c
+++ b/src/network/networkd-network.c
@@ -405,6 +405,7 @@ int network_load_one(Manager *manager, OrderedHashmap **networks, const char *fi
                 .dhcp6_use_hostname = true,
                 .dhcp6_use_ntp = true,
                 .dhcp6_duid.type = _DUID_TYPE_INVALID,
+                .dhcp6_client_start_mode = _DHCP6_CLIENT_START_MODE_INVALID,
 
                 .dhcp6_pd = -1,
                 .dhcp6_pd_announce = true,
diff --git a/src/network/networkd-network.h b/src/network/networkd-network.h
index bd9758c899..d10119f58c 100644
--- a/src/network/networkd-network.h
+++ b/src/network/networkd-network.h
@@ -185,12 +185,10 @@ struct Network {
         char *dhcp6_mudurl;
         char **dhcp6_user_class;
         char **dhcp6_vendor_class;
-        DHCP6ClientStartMode dhcp6_without_ra;
+        DHCP6ClientStartMode dhcp6_client_start_mode;
         OrderedHashmap *dhcp6_client_send_options;
         OrderedHashmap *dhcp6_client_send_vendor_options;
         Set *dhcp6_request_options;
-        /* Start DHCPv6 PD also when 'O' RA flag is set, see RFC 7084, WPD-4 */
-        bool dhcp6_force_pd_other_information;
 
         /* DHCP Server Support */
         bool dhcp_server;