+static int server_message_init(sd_dhcp_server *server, DHCPPacket **ret,
+ uint8_t type, size_t *_optoffset, DHCPRequest *req) {
+ _cleanup_free_ DHCPPacket *packet = NULL;
+ size_t optoffset = 0;
+ int r;
+
+ assert(server);
+ assert(ret);
+ assert(_optoffset);
+ assert(IN_SET(type, DHCP_OFFER, DHCP_ACK, DHCP_NAK));
+
+ packet = malloc0(sizeof(DHCPPacket) + req->max_optlen);
+ if (!packet)
+ return -ENOMEM;
+
+ r = dhcp_message_init(&packet->dhcp, BOOTREPLY, be32toh(req->message->xid),
+ type, req->max_optlen, &optoffset);
+ if (r < 0)
+ return r;
+
+ packet->dhcp.flags = req->message->flags;
+ packet->dhcp.giaddr = req->message->giaddr;
+ memcpy(&packet->dhcp.chaddr, &req->message->chaddr, ETH_ALEN);
+
+ *_optoffset = optoffset;
+ *ret = packet;
+ packet = NULL;
+
+ return 0;
+}
+
+static int server_send_offer(sd_dhcp_server *server, DHCPRequest *req, be32_t address) {
+ _cleanup_free_ DHCPPacket *packet = NULL;
+ size_t offset;
+ be32_t lease_time;
+ int r;
+
+ r = server_message_init(server, &packet, DHCP_OFFER, &offset, req);
+ if (r < 0)
+ return r;
+
+ packet->dhcp.yiaddr = address;
+
+ lease_time = htobe32(req->lifetime);
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+ DHCP_OPTION_IP_ADDRESS_LEASE_TIME, 4, &lease_time);
+ if (r < 0)
+ return r;
+
+ r = dhcp_server_send_packet(server, req, packet, DHCP_OFFER, offset);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+static int server_send_ack(sd_dhcp_server *server, DHCPRequest *req, be32_t address) {
+ _cleanup_free_ DHCPPacket *packet = NULL;
+ size_t offset;
+ be32_t lease_time;
+ int r;
+
+ r = server_message_init(server, &packet, DHCP_ACK, &offset, req);
+ if (r < 0)
+ return r;
+
+ packet->dhcp.yiaddr = address;
+
+ lease_time = htobe32(req->lifetime);
+ r = dhcp_option_append(&packet->dhcp, req->max_optlen, &offset, 0,
+ DHCP_OPTION_IP_ADDRESS_LEASE_TIME, 4, &lease_time);
+ if (r < 0)
+ return r;
+
+ r = dhcp_server_send_packet(server, req, packet, DHCP_ACK, offset);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+static int server_send_nak(sd_dhcp_server *server, DHCPRequest *req) {
+ _cleanup_free_ DHCPPacket *packet = NULL;
+ size_t offset;
+ int r;
+
+ r = server_message_init(server, &packet, DHCP_NAK, &offset, req);
+ if (r < 0)
+ return r;
+
+ r = dhcp_server_send_packet(server, req, packet, DHCP_NAK, offset);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+static int server_send_forcerenew(sd_dhcp_server *server, be32_t address, be32_t gateway,
+ uint8_t chaddr[]) {
+ _cleanup_free_ DHCPPacket *packet = NULL;
+ size_t optoffset = 0;
+ int r;
+
+ assert(server);
+ assert(address != INADDR_ANY);
+ assert(chaddr);
+
+ packet = malloc0(sizeof(DHCPPacket) + DHCP_MIN_OPTIONS_SIZE);
+ if (!packet)
+ return -ENOMEM;
+
+ r = dhcp_message_init(&packet->dhcp, BOOTREPLY, 0,
+ DHCP_FORCERENEW, DHCP_MIN_OPTIONS_SIZE,
+ &optoffset);
+ if (r < 0)
+ return r;
+
+ r = dhcp_option_append(&packet->dhcp, DHCP_MIN_OPTIONS_SIZE,
+ &optoffset, 0, DHCP_OPTION_END, 0, NULL);
+ if (r < 0)
+ return r;
+
+ memcpy(&packet->dhcp.chaddr, chaddr, ETH_ALEN);
+
+ r = dhcp_server_send_udp(server, address, &packet->dhcp,
+ sizeof(DHCPMessage) + optoffset);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+