3 * Construct and send DHCP server packets
5 * Russ Dill <Russ.Dill@asu.edu> July 2001
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 #include <sys/socket.h>
23 #include <netinet/in.h>
24 #include <arpa/inet.h>
29 #include "serverpacket.h"
32 #include "static_leases.h"
34 /* send a packet to giaddr using the kernel ip stack */
35 static int send_packet_to_relay(struct dhcpMessage *payload)
37 DEBUG(LOG_INFO, "Forwarding packet to relay");
39 return kernel_packet(payload, server_config.server, SERVER_PORT,
40 payload->giaddr, SERVER_PORT);
44 /* send a packet to a specific arp address and ip address by creating our own ip packet */
45 static int send_packet_to_client(struct dhcpMessage *payload, int force_broadcast)
50 if (force_broadcast) {
51 DEBUG(LOG_INFO, "broadcasting packet to client (NAK)");
52 ciaddr = INADDR_BROADCAST;
53 chaddr = MAC_BCAST_ADDR;
54 } else if (payload->ciaddr) {
55 DEBUG(LOG_INFO, "unicasting packet to client ciaddr");
56 ciaddr = payload->ciaddr;
57 chaddr = payload->chaddr;
58 } else if (ntohs(payload->flags) & BROADCAST_FLAG) {
59 DEBUG(LOG_INFO, "broadcasting packet to client (requested)");
60 ciaddr = INADDR_BROADCAST;
61 chaddr = MAC_BCAST_ADDR;
63 DEBUG(LOG_INFO, "unicasting packet to client yiaddr");
64 ciaddr = payload->yiaddr;
65 chaddr = payload->chaddr;
67 return raw_packet(payload, server_config.server, SERVER_PORT,
68 ciaddr, CLIENT_PORT, chaddr, server_config.ifindex);
72 /* send a dhcp packet, if force broadcast is set, the packet will be broadcast to the client */
73 static int send_packet(struct dhcpMessage *payload, int force_broadcast)
78 ret = send_packet_to_relay(payload);
79 else ret = send_packet_to_client(payload, force_broadcast);
84 static void init_packet(struct dhcpMessage *packet, struct dhcpMessage *oldpacket, char type)
86 init_header(packet, type);
87 packet->xid = oldpacket->xid;
88 memcpy(packet->chaddr, oldpacket->chaddr, 16);
89 packet->flags = oldpacket->flags;
90 packet->giaddr = oldpacket->giaddr;
91 packet->ciaddr = oldpacket->ciaddr;
92 add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server);
96 /* add in the bootp options */
97 static void add_bootp_options(struct dhcpMessage *packet)
99 packet->siaddr = server_config.siaddr;
100 if (server_config.sname)
101 strncpy(packet->sname, server_config.sname, sizeof(packet->sname) - 1);
102 if (server_config.boot_file)
103 strncpy(packet->file, server_config.boot_file, sizeof(packet->file) - 1);
107 /* send a DHCP OFFER to a DHCP DISCOVER */
108 int sendOffer(struct dhcpMessage *oldpacket)
110 struct dhcpMessage packet;
111 struct dhcpOfferedAddr *lease = NULL;
112 uint32_t req_align, lease_time_align = server_config.lease;
113 uint8_t *req, *lease_time;
114 struct option_set *curr;
117 uint32_t static_lease_ip;
119 init_packet(&packet, oldpacket, DHCPOFFER);
121 static_lease_ip = getIpByMac(server_config.static_leases, oldpacket->chaddr);
123 /* ADDME: if static, short circuit */
126 /* the client is in our lease/offered table */
127 if ((lease = find_lease_by_chaddr(oldpacket->chaddr))) {
128 if (!lease_expired(lease))
129 lease_time_align = lease->expires - time(0);
130 packet.yiaddr = lease->yiaddr;
132 /* Or the client has a requested ip */
133 } else if ((req = get_option(oldpacket, DHCP_REQUESTED_IP)) &&
135 /* Don't look here (ugly hackish thing to do) */
136 memcpy(&req_align, req, 4) &&
138 /* and the ip is in the lease range */
139 ntohl(req_align) >= ntohl(server_config.start) &&
140 ntohl(req_align) <= ntohl(server_config.end) &&
142 !static_lease_ip && /* Check that its not a static lease */
143 /* and is not already taken/offered */
144 ((!(lease = find_lease_by_yiaddr(req_align)) ||
146 /* or its taken, but expired */ /* ADDME: or maybe in here */
147 lease_expired(lease)))) {
148 packet.yiaddr = req_align; /* FIXME: oh my, is there a host using this IP? */
150 /* otherwise, find a free IP */
152 /* Is it a static lease? (No, because find_address skips static lease) */
153 packet.yiaddr = find_address(0);
155 /* try for an expired lease */
156 if (!packet.yiaddr) packet.yiaddr = find_address(1);
160 LOG(LOG_WARNING, "no IP addresses to give -- OFFER abandoned");
164 if (!add_lease(packet.chaddr, packet.yiaddr, server_config.offer_time)) {
165 LOG(LOG_WARNING, "lease pool is full -- OFFER abandoned");
169 if ((lease_time = get_option(oldpacket, DHCP_LEASE_TIME))) {
170 memcpy(&lease_time_align, lease_time, 4);
171 lease_time_align = ntohl(lease_time_align);
172 if (lease_time_align > server_config.lease)
173 lease_time_align = server_config.lease;
176 /* Make sure we aren't just using the lease time from the previous offer */
177 if (lease_time_align < server_config.min_lease)
178 lease_time_align = server_config.lease;
180 /* ADDME: end of short circuit */
183 /* It is a static lease... use it */
184 packet.yiaddr = static_lease_ip;
187 add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
189 curr = server_config.options;
191 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
192 add_option_string(packet.options, curr->data);
196 add_bootp_options(&packet);
198 addr.s_addr = packet.yiaddr;
199 LOG(LOG_INFO, "sending OFFER of %s", inet_ntoa(addr));
200 return send_packet(&packet, 0);
204 int sendNAK(struct dhcpMessage *oldpacket)
206 struct dhcpMessage packet;
208 init_packet(&packet, oldpacket, DHCPNAK);
210 DEBUG(LOG_INFO, "sending NAK");
211 return send_packet(&packet, 1);
215 int sendACK(struct dhcpMessage *oldpacket, uint32_t yiaddr)
217 struct dhcpMessage packet;
218 struct option_set *curr;
220 uint32_t lease_time_align = server_config.lease;
223 init_packet(&packet, oldpacket, DHCPACK);
224 packet.yiaddr = yiaddr;
226 if ((lease_time = get_option(oldpacket, DHCP_LEASE_TIME))) {
227 memcpy(&lease_time_align, lease_time, 4);
228 lease_time_align = ntohl(lease_time_align);
229 if (lease_time_align > server_config.lease)
230 lease_time_align = server_config.lease;
231 else if (lease_time_align < server_config.min_lease)
232 lease_time_align = server_config.lease;
235 add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
237 curr = server_config.options;
239 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
240 add_option_string(packet.options, curr->data);
244 add_bootp_options(&packet);
246 addr.s_addr = packet.yiaddr;
247 LOG(LOG_INFO, "sending ACK to %s", inet_ntoa(addr));
249 if (send_packet(&packet, 0) < 0)
252 add_lease(packet.chaddr, packet.yiaddr, lease_time_align);
258 int send_inform(struct dhcpMessage *oldpacket)
260 struct dhcpMessage packet;
261 struct option_set *curr;
263 init_packet(&packet, oldpacket, DHCPACK);
265 curr = server_config.options;
267 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
268 add_option_string(packet.options, curr->data);
272 add_bootp_options(&packet);
274 return send_packet(&packet, 0);