network: introduce [DHCPv4] RequestAddress= setting

This may be useful when requesting a specific address.

Closes #29437.

diff --git a/man/systemd.network.xml b/man/systemd.network.xml
index 8d462615ac6211c485c2792ee49fc48212ff18c2..33c559cddb5223a073ab3ad6c03a9c735c421b90 100644 (file)
--- a/man/systemd.network.xml
+++ b/man/systemd.network.xml
@@ -2098,6 +2098,17 @@ NFTSet=prefix:netdev:filter:eth_ipv4_prefix</programlisting>
 
       <!-- DHCP packet contents -->
 
+      <varlistentry>
+        <term><varname>RequestAddress=</varname></term>
+        <listitem>
+          <para>Takes an IPv4 address. When specified, the Requested IP Address option (option code 50) is
+          added with it to the initial DHCPDISCOVER message sent by the DHCP client. Defaults to unset, and
+          an already assigned dynamic address to the interface is automatically picked.</para>
+
+          <xi:include href="version-info.xml" xpointer="v255"/>
+        </listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><varname>SendHostname=</varname></term>
         <listitem>
@@ -2232,6 +2243,7 @@ NFTSet=prefix:netdev:filter:eth_ipv4_prefix</programlisting>
           are implied and these settings in the .network file are silently ignored. Also,
           <varname>Hostname=</varname>,
           <varname>MUDURL=</varname>,
+          <varname>RequestAddress</varname>,
           <varname>RequestOptions=</varname>,
           <varname>SendOption=</varname>,
           <varname>SendVendorOption=</varname>,

diff --git a/src/network/networkd-dhcp4.c b/src/network/networkd-dhcp4.c
index 2a6237c6d5159979cac6c83704109eed34f988e0..3e8038ede6b71ea648d0530f6526350b42cc21a7 100644 (file)
--- a/src/network/networkd-dhcp4.c
+++ b/src/network/networkd-dhcp4.c
@@ -1383,15 +1383,15 @@ static int dhcp4_set_client_identifier(Link *link) {
         return 0;
 }
 
-static int dhcp4_set_request_address(Link *link) {
+static int dhcp4_find_dynamic_address(Link *link, struct in_addr *ret) {
         Address *a;
 
         assert(link);
         assert(link->network);
-        assert(link->dhcp_client);
+        assert(ret);
 
         if (!FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP))
-                return 0;
+                return false;
 
         SET_FOREACH(a, link->addresses) {
                 if (a->source != NETWORK_CONFIG_SOURCE_FOREIGN)
@@ -1403,11 +1403,29 @@ static int dhcp4_set_request_address(Link *link) {
         }
 
         if (!a)
-                return 0;
+                return false;
+
+        *ret = a->in_addr.in;
+        return true;
+}
+
+static int dhcp4_set_request_address(Link *link) {
+        struct in_addr a;
+
+        assert(link);
+        assert(link->network);
+        assert(link->dhcp_client);
+
+        a = link->network->dhcp_request_address;
 
-        log_link_debug(link, "DHCPv4 CLIENT: requesting " IPV4_ADDRESS_FMT_STR, IPV4_ADDRESS_FMT_VAL(a->in_addr.in));
+        if (in4_addr_is_null(&a))
+                (void) dhcp4_find_dynamic_address(link, &a);
+
+        if (in4_addr_is_null(&a))
+                return 0;
 
-        return sd_dhcp_client_set_request_address(link->dhcp_client, &a->in_addr.in);
+        log_link_debug(link, "DHCPv4 CLIENT: requesting %s.", IN4_ADDR_TO_STRING(&a));
+        return sd_dhcp_client_set_request_address(link->dhcp_client, &a);
 }
 
 static bool link_needs_dhcp_broadcast(Link *link) {

diff --git a/src/network/networkd-network-gperf.gperf b/src/network/networkd-network-gperf.gperf
index ab456efb9e98549cb7be74fc7b31bc3eb163a4d8..42e989e11608499b23b47c9e0358b1d504fc9907 100644 (file)
--- a/src/network/networkd-network-gperf.gperf
+++ b/src/network/networkd-network-gperf.gperf
@@ -214,6 +214,7 @@ NextHop.Family,                              config_parse_nexthop_family,
 NextHop.OnLink,                              config_parse_nexthop_onlink,                              0,                             0
 NextHop.Blackhole,                           config_parse_nexthop_blackhole,                           0,                             0
 NextHop.Group,                               config_parse_nexthop_group,                               0,                             0
+DHCPv4.RequestAddress,                       config_parse_in_addr_non_null,                            AF_INET,                       offsetof(Network, dhcp_request_address)
 DHCPv4.ClientIdentifier,                     config_parse_dhcp_client_identifier,                      0,                             offsetof(Network, dhcp_client_identifier)
 DHCPv4.UseDNS,                               config_parse_dhcp_use_dns,                                AF_INET,                       0
 DHCPv4.RoutesToDNS,                          config_parse_bool,                                        0,                             offsetof(Network, dhcp_routes_to_dns)

diff --git a/src/network/networkd-network.h b/src/network/networkd-network.h
index 34bc179d75bbfa50b633b717579c990f963880cd..cc2cf36f5ce6049617d2fe585f46f4d7d05fcbee 100644 (file)
--- a/src/network/networkd-network.h
+++ b/src/network/networkd-network.h
@@ -114,6 +114,7 @@ struct Network {
 
         /* DHCP Client Support */
         AddressFamily dhcp;
+        struct in_addr dhcp_request_address;
         DHCPClientIdentifier dhcp_client_identifier;
         DUID dhcp_duid;
         uint32_t dhcp_iaid;