--- /dev/null
+/* serverpacket.c
+ *
+ * Construct and send DHCP server packets
+ *
+ * Russ Dill <Russ.Dill@asu.edu> July 2001
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <string.h>
+#include <time.h>
+
+#include "serverpacket.h"
+#include "dhcpd.h"
+#include "options.h"
+#include "common.h"
+#include "static_leases.h"
+
+/* send a packet to giaddr using the kernel ip stack */
+static int send_packet_to_relay(struct dhcpMessage *payload)
+{
+ DEBUG(LOG_INFO, "Forwarding packet to relay");
+
+ return kernel_packet(payload, server_config.server, SERVER_PORT,
+ payload->giaddr, SERVER_PORT);
+}
+
+
+/* send a packet to a specific arp address and ip address by creating our own ip packet */
+static int send_packet_to_client(struct dhcpMessage *payload, int force_broadcast)
+{
+ uint8_t *chaddr;
+ uint32_t ciaddr;
+
+ if (force_broadcast) {
+ DEBUG(LOG_INFO, "broadcasting packet to client (NAK)");
+ ciaddr = INADDR_BROADCAST;
+ chaddr = MAC_BCAST_ADDR;
+ } else if (payload->ciaddr) {
+ DEBUG(LOG_INFO, "unicasting packet to client ciaddr");
+ ciaddr = payload->ciaddr;
+ chaddr = payload->chaddr;
+ } else if (ntohs(payload->flags) & BROADCAST_FLAG) {
+ DEBUG(LOG_INFO, "broadcasting packet to client (requested)");
+ ciaddr = INADDR_BROADCAST;
+ chaddr = MAC_BCAST_ADDR;
+ } else {
+ DEBUG(LOG_INFO, "unicasting packet to client yiaddr");
+ ciaddr = payload->yiaddr;
+ chaddr = payload->chaddr;
+ }
+ return raw_packet(payload, server_config.server, SERVER_PORT,
+ ciaddr, CLIENT_PORT, chaddr, server_config.ifindex);
+}
+
+
+/* send a dhcp packet, if force broadcast is set, the packet will be broadcast to the client */
+static int send_packet(struct dhcpMessage *payload, int force_broadcast)
+{
+ int ret;
+
+ if (payload->giaddr)
+ ret = send_packet_to_relay(payload);
+ else ret = send_packet_to_client(payload, force_broadcast);
+ return ret;
+}
+
+
+static void init_packet(struct dhcpMessage *packet, struct dhcpMessage *oldpacket, char type)
+{
+ init_header(packet, type);
+ packet->xid = oldpacket->xid;
+ memcpy(packet->chaddr, oldpacket->chaddr, 16);
+ packet->flags = oldpacket->flags;
+ packet->giaddr = oldpacket->giaddr;
+ packet->ciaddr = oldpacket->ciaddr;
+ add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server);
+}
+
+
+/* add in the bootp options */
+static void add_bootp_options(struct dhcpMessage *packet)
+{
+ packet->siaddr = server_config.siaddr;
+ if (server_config.sname)
+ strncpy(packet->sname, server_config.sname, sizeof(packet->sname) - 1);
+ if (server_config.boot_file)
+ strncpy(packet->file, server_config.boot_file, sizeof(packet->file) - 1);
+}
+
+
+/* send a DHCP OFFER to a DHCP DISCOVER */
+int sendOffer(struct dhcpMessage *oldpacket)
+{
+ struct dhcpMessage packet;
+ struct dhcpOfferedAddr *lease = NULL;
+ uint32_t req_align, lease_time_align = server_config.lease;
+ uint8_t *req, *lease_time;
+ struct option_set *curr;
+ struct in_addr addr;
+
+ uint32_t static_lease_ip;
+
+ init_packet(&packet, oldpacket, DHCPOFFER);
+
+ static_lease_ip = getIpByMac(server_config.static_leases, oldpacket->chaddr);
+
+ /* ADDME: if static, short circuit */
+ if(!static_lease_ip)
+ {
+ /* the client is in our lease/offered table */
+ if ((lease = find_lease_by_chaddr(oldpacket->chaddr))) {
+ if (!lease_expired(lease))
+ lease_time_align = lease->expires - time(0);
+ packet.yiaddr = lease->yiaddr;
+
+ /* Or the client has a requested ip */
+ } else if ((req = get_option(oldpacket, DHCP_REQUESTED_IP)) &&
+
+ /* Don't look here (ugly hackish thing to do) */
+ memcpy(&req_align, req, 4) &&
+
+ /* and the ip is in the lease range */
+ ntohl(req_align) >= ntohl(server_config.start) &&
+ ntohl(req_align) <= ntohl(server_config.end) &&
+
+ !static_lease_ip && /* Check that its not a static lease */
+ /* and is not already taken/offered */
+ ((!(lease = find_lease_by_yiaddr(req_align)) ||
+
+ /* or its taken, but expired */ /* ADDME: or maybe in here */
+ lease_expired(lease)))) {
+ packet.yiaddr = req_align; /* FIXME: oh my, is there a host using this IP? */
+
+ /* otherwise, find a free IP */
+ } else {
+ /* Is it a static lease? (No, because find_address skips static lease) */
+ packet.yiaddr = find_address(0);
+
+ /* try for an expired lease */
+ if (!packet.yiaddr) packet.yiaddr = find_address(1);
+ }
+
+ if(!packet.yiaddr) {
+ LOG(LOG_WARNING, "no IP addresses to give -- OFFER abandoned");
+ return -1;
+ }
+
+ if (!add_lease(packet.chaddr, packet.yiaddr, server_config.offer_time)) {
+ LOG(LOG_WARNING, "lease pool is full -- OFFER abandoned");
+ return -1;
+ }
+
+ if ((lease_time = get_option(oldpacket, DHCP_LEASE_TIME))) {
+ memcpy(&lease_time_align, lease_time, 4);
+ lease_time_align = ntohl(lease_time_align);
+ if (lease_time_align > server_config.lease)
+ lease_time_align = server_config.lease;
+ }
+
+ /* Make sure we aren't just using the lease time from the previous offer */
+ if (lease_time_align < server_config.min_lease)
+ lease_time_align = server_config.lease;
+ }
+ /* ADDME: end of short circuit */
+ else
+ {
+ /* It is a static lease... use it */
+ packet.yiaddr = static_lease_ip;
+ }
+
+ add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
+
+ curr = server_config.options;
+ while (curr) {
+ if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
+ add_option_string(packet.options, curr->data);
+ curr = curr->next;
+ }
+
+ add_bootp_options(&packet);
+
+ addr.s_addr = packet.yiaddr;
+ LOG(LOG_INFO, "sending OFFER of %s", inet_ntoa(addr));
+ return send_packet(&packet, 0);
+}
+
+
+int sendNAK(struct dhcpMessage *oldpacket)
+{
+ struct dhcpMessage packet;
+
+ init_packet(&packet, oldpacket, DHCPNAK);
+
+ DEBUG(LOG_INFO, "sending NAK");
+ return send_packet(&packet, 1);
+}
+
+
+int sendACK(struct dhcpMessage *oldpacket, uint32_t yiaddr)
+{
+ struct dhcpMessage packet;
+ struct option_set *curr;
+ uint8_t *lease_time;
+ uint32_t lease_time_align = server_config.lease;
+ struct in_addr addr;
+
+ init_packet(&packet, oldpacket, DHCPACK);
+ packet.yiaddr = yiaddr;
+
+ if ((lease_time = get_option(oldpacket, DHCP_LEASE_TIME))) {
+ memcpy(&lease_time_align, lease_time, 4);
+ lease_time_align = ntohl(lease_time_align);
+ if (lease_time_align > server_config.lease)
+ lease_time_align = server_config.lease;
+ else if (lease_time_align < server_config.min_lease)
+ lease_time_align = server_config.lease;
+ }
+
+ add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
+
+ curr = server_config.options;
+ while (curr) {
+ if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
+ add_option_string(packet.options, curr->data);
+ curr = curr->next;
+ }
+
+ add_bootp_options(&packet);
+
+ addr.s_addr = packet.yiaddr;
+ LOG(LOG_INFO, "sending ACK to %s", inet_ntoa(addr));
+
+ if (send_packet(&packet, 0) < 0)
+ return -1;
+
+ add_lease(packet.chaddr, packet.yiaddr, lease_time_align);
+
+ return 0;
+}
+
+
+int send_inform(struct dhcpMessage *oldpacket)
+{
+ struct dhcpMessage packet;
+ struct option_set *curr;
+
+ init_packet(&packet, oldpacket, DHCPACK);
+
+ curr = server_config.options;
+ while (curr) {
+ if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
+ add_option_string(packet.options, curr->data);
+ curr = curr->next;
+ }
+
+ add_bootp_options(&packet);
+
+ return send_packet(&packet, 0);
+}
projects / grml-terminalserver.git / blobdiff