Merge pull request #22615 from yuwata/network-dhcp-server-support-pxe-boot-systems

network: dhcp server: support pxe boot systems

man/systemd.network.xml

@@ -2626,6 +2626,23 @@ Token=prefixstable:2002:da8:1::</programlisting></para>
         <filename>/etc/localtime</filename> symlink.</para></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><varname>NextServer=</varname></term>
+
+        <listitem>
+          <para>Takes an IPv4 address. Configures the next server used by e.g. PXE boot systems.
+          Defaults to unset.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>Filename=</varname></term>
+
+        <listitem>
+          <para>Takes a path or url to a file loaded by e.g. a PXE boot loader. Defaults to unset.</para>
+        </listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><varname>SendOption=</varname></term>
         <listitem>

src/libsystemd-network/dhcp-server-internal.h

@@ -65,6 +65,8 @@ struct sd_dhcp_server {
         char *timezone;
 
         DHCPServerData servers[_SD_DHCP_LEASE_SERVER_TYPE_MAX];
+        struct in_addr next_server;
+        char *filename;
 
         OrderedSet *extra_options;
         OrderedSet *vendor_options;

src/libsystemd-network/sd-dhcp-server.c

@@ -21,6 +21,7 @@
 #include "siphash24.h"
 #include "string-util.h"
 #include "unaligned.h"
+#include "utf8.h"
 
 #define DHCP_DEFAULT_LEASE_TIME_USEC USEC_PER_HOUR
 #define DHCP_MAX_LEASE_TIME_USEC (USEC_PER_HOUR*12)
@@ -162,6 +163,7 @@ static sd_dhcp_server *dhcp_server_free(sd_dhcp_server *server) {
 
         sd_event_unref(server->event);
 
+        free(server->filename);
         free(server->timezone);
 
         for (sd_dhcp_lease_server_type_t i = 0; i < _SD_DHCP_LEASE_SERVER_TYPE_MAX; i++)
@@ -270,6 +272,26 @@ sd_event *sd_dhcp_server_get_event(sd_dhcp_server *server) {
         return server->event;
 }
 
+int sd_dhcp_server_set_next_server(sd_dhcp_server *server, const struct in_addr *next_server) {
+        assert_return(server, -EINVAL);
+
+        if (next_server)
+                server->next_server = *next_server;
+        else
+                server->next_server = (struct in_addr) {};
+
+        return 0;
+}
+
+int sd_dhcp_server_set_filename(sd_dhcp_server *server, const char *filename) {
+        assert_return(server, -EINVAL);
+
+        if (filename && !ascii_is_valid(filename))
+                return -EINVAL;
+
+        return free_and_strdup(&server->filename, filename);
+}
+
 int sd_dhcp_server_stop(sd_dhcp_server *server) {
         bool running;
 
@@ -539,6 +561,7 @@ static int server_send_offer_or_ack(
                 return r;
 
         packet->dhcp.yiaddr = address;
+        packet->dhcp.siaddr = server->next_server.s_addr;
 
         lease_time = htobe32(req->lifetime);
         r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
@@ -562,6 +585,22 @@ static int server_send_offer_or_ack(
                         return r;
         }
 
+        if (server->filename) {
+                /* The pxelinux magic option is marked as deprecated, but let's append it for older
+                 * implementations. */
+                r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+                                       SD_DHCP_OPTION_PXELINUX_MAGIC, 4,
+                                       (const uint8_t[]) { 0xf1, 0x00, 0x74, 0x7e });
+                if (r < 0)
+                        return r;
+
+                r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+                                       SD_DHCP_OPTION_CONFIGURATION_FILE,
+                                       strlen(server->filename), server->filename);
+                if (r < 0)
+                        return r;
+        }
+
         if (type == DHCP_ACK) {
                 static const uint8_t option_map[_SD_DHCP_LEASE_SERVER_TYPE_MAX] = {
                         [SD_DHCP_LEASE_DNS] = SD_DHCP_OPTION_DOMAIN_NAME_SERVER,

src/network/networkd-dhcp-server.c

@@ -416,6 +416,14 @@ static int dhcp4_server_configure(Link *link) {
                         return log_link_error_errno(link, r, "Failed to set default lease time for DHCPv4 server instance: %m");
         }
 
+        r = sd_dhcp_server_set_next_server(link->dhcp_server, &link->network->dhcp_server_next_server);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to set next server for DHCPv4 server instance: %m");
+
+        r = sd_dhcp_server_set_filename(link->dhcp_server, link->network->dhcp_server_filename);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to set filename for DHCPv4 server instance: %m");
+
         for (sd_dhcp_lease_server_type_t type = 0; type < _SD_DHCP_LEASE_SERVER_TYPE_MAX; type ++) {
 
                 if (!link->network->dhcp_server_emit[type].emit)

src/network/networkd-network-gperf.gperf

@@ -305,6 +305,8 @@ DHCPServer.PoolSize,                         config_parse_uint32,
 DHCPServer.SendVendorOption,                 config_parse_dhcp_send_option,                            0,                             offsetof(Network, dhcp_server_send_vendor_options)
 DHCPServer.SendOption,                       config_parse_dhcp_send_option,                            0,                             offsetof(Network, dhcp_server_send_options)
 DHCPServer.BindToInterface,                  config_parse_bool,                                        0,                             offsetof(Network, dhcp_server_bind_to_interface)
+DHCPServer.NextServer,                       config_parse_in_addr_non_null,                            AF_INET,                       offsetof(Network, dhcp_server_next_server)
+DHCPServer.Filename,                         config_parse_string,                                      0,                             offsetof(Network, dhcp_server_filename)
 DHCPServerStaticLease.Address,               config_parse_dhcp_static_lease_address,                   0,                             0
 DHCPServerStaticLease.MACAddress,            config_parse_dhcp_static_lease_hwaddr,                    0,                             0
 Bridge.Cost,                                 config_parse_uint32,                                      0,                             offsetof(Network, cost)

src/network/networkd-network.c

@@ -700,6 +700,7 @@ static Network *network_free(Network *network) {
 
         free(network->dhcp_server_relay_agent_circuit_id);
         free(network->dhcp_server_relay_agent_remote_id);
+        free(network->dhcp_server_filename);
 
         free(network->description);
         free(network->dhcp_vendor_class_identifier);

src/network/networkd-network.h

@@ -200,6 +200,8 @@ struct Network {
         uint32_t dhcp_server_pool_size;
         OrderedHashmap *dhcp_server_send_options;
         OrderedHashmap *dhcp_server_send_vendor_options;
+        struct in_addr dhcp_server_next_server;
+        char *dhcp_server_filename;
 
         /* link local addressing support */
         AddressFamily link_local;

src/systemd/sd-dhcp-client.h

@@ -97,6 +97,10 @@ enum {
         SD_DHCP_OPTION_SIP_SERVER                     = 120,
         SD_DHCP_OPTION_CLASSLESS_STATIC_ROUTE         = 121,
         SD_DHCP_OPTION_MUD_URL                        = 161,
+        SD_DHCP_OPTION_PXELINUX_MAGIC                 = 208, /* deprecated */
+        SD_DHCP_OPTION_CONFIGURATION_FILE             = 209,
+        SD_DHCP_OPTION_PATH_PREFIX                    = 210,
+        SD_DHCP_OPTION_REBOOT_TIME                    = 211,
         SD_DHCP_OPTION_6RD                            = 212,
         SD_DHCP_OPTION_PRIVATE_BASE                   = 224,
         /* Windows 10 option to send when Anonymize=true */

src/systemd/sd-dhcp-server.h

@@ -58,6 +58,8 @@ int sd_dhcp_server_stop(sd_dhcp_server *server);
 
 int sd_dhcp_server_configure_pool(sd_dhcp_server *server, const struct in_addr *address, unsigned char prefixlen, uint32_t offset, uint32_t size);
 
+int sd_dhcp_server_set_next_server(sd_dhcp_server *server, const struct in_addr *next_server);
+int sd_dhcp_server_set_filename(sd_dhcp_server *server, const char *filename);
 int sd_dhcp_server_set_bind_to_interface(sd_dhcp_server *server, int enabled);
 int sd_dhcp_server_set_timezone(sd_dhcp_server *server, const char *timezone);
 int sd_dhcp_server_set_router(sd_dhcp_server *server, const struct in_addr *address);

test/fuzz/fuzz-network-parser/directives.network

@@ -409,6 +409,8 @@ RelayAgentCircuitId=
 RelayAgentRemoteId=
 ServerAddress=
 UplinkInterface=
+NextServer=
+Filename=
 [DHCPServerStaticLease]
 MACAddress=
 Address=