1 /* vi: set sw=4 ts=4: */
4 * Construct and send DHCP server packets
6 * Russ Dill <Russ.Dill@asu.edu> July 2001
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
28 /* send a packet to giaddr using the kernel ip stack */
29 static int send_packet_to_relay(struct dhcpMessage *payload)
31 DEBUG("Forwarding packet to relay");
33 return udhcp_kernel_packet(payload, server_config.server, SERVER_PORT,
34 payload->giaddr, SERVER_PORT);
38 /* send a packet to a specific arp address and ip address by creating our own ip packet */
39 static int send_packet_to_client(struct dhcpMessage *payload, int force_broadcast)
44 if (force_broadcast) {
45 DEBUG("broadcasting packet to client (NAK)");
46 ciaddr = INADDR_BROADCAST;
47 chaddr = MAC_BCAST_ADDR;
48 } else if (payload->ciaddr) {
49 DEBUG("unicasting packet to client ciaddr");
50 ciaddr = payload->ciaddr;
51 chaddr = payload->chaddr;
52 } else if (ntohs(payload->flags) & BROADCAST_FLAG) {
53 DEBUG("broadcasting packet to client (requested)");
54 ciaddr = INADDR_BROADCAST;
55 chaddr = MAC_BCAST_ADDR;
57 DEBUG("unicasting packet to client yiaddr");
58 ciaddr = payload->yiaddr;
59 chaddr = payload->chaddr;
61 return udhcp_raw_packet(payload, server_config.server, SERVER_PORT,
62 ciaddr, CLIENT_PORT, chaddr, server_config.ifindex);
66 /* send a dhcp packet, if force broadcast is set, the packet will be broadcast to the client */
67 static int send_packet(struct dhcpMessage *payload, int force_broadcast)
72 ret = send_packet_to_relay(payload);
73 else ret = send_packet_to_client(payload, force_broadcast);
78 static void init_packet(struct dhcpMessage *packet, struct dhcpMessage *oldpacket, char type)
80 udhcp_init_header(packet, type);
81 packet->xid = oldpacket->xid;
82 memcpy(packet->chaddr, oldpacket->chaddr, 16);
83 packet->flags = oldpacket->flags;
84 packet->giaddr = oldpacket->giaddr;
85 packet->ciaddr = oldpacket->ciaddr;
86 add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server);
90 /* add in the bootp options */
91 static void add_bootp_options(struct dhcpMessage *packet)
93 packet->siaddr = server_config.siaddr;
94 if (server_config.sname)
95 strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1);
96 if (server_config.boot_file)
97 strncpy((char*)packet->file, server_config.boot_file, sizeof(packet->file) - 1);
101 /* send a DHCP OFFER to a DHCP DISCOVER */
102 int sendOffer(struct dhcpMessage *oldpacket)
104 struct dhcpMessage packet;
105 struct dhcpOfferedAddr *lease = NULL;
106 uint32_t req_align, lease_time_align = server_config.lease;
107 uint8_t *req, *lease_time;
108 struct option_set *curr;
111 uint32_t static_lease_ip;
113 init_packet(&packet, oldpacket, DHCPOFFER);
115 static_lease_ip = getIpByMac(server_config.static_leases, oldpacket->chaddr);
117 /* ADDME: if static, short circuit */
118 if (!static_lease_ip) {
119 /* the client is in our lease/offered table */
120 lease = find_lease_by_chaddr(oldpacket->chaddr);
122 if (!lease_expired(lease))
123 lease_time_align = lease->expires - time(0);
124 packet.yiaddr = lease->yiaddr;
126 /* Or the client has a requested ip */
127 } else if ((req = get_option(oldpacket, DHCP_REQUESTED_IP))
128 /* Don't look here (ugly hackish thing to do) */
129 && memcpy(&req_align, req, 4)
130 /* and the ip is in the lease range */
131 && ntohl(req_align) >= ntohl(server_config.start)
132 && ntohl(req_align) <= ntohl(server_config.end)
133 && !static_lease_ip /* Check that its not a static lease */
134 /* and is not already taken/offered */
135 && (!(lease = find_lease_by_yiaddr(req_align))
136 /* or its taken, but expired */ /* ADDME: or maybe in here */
137 || lease_expired(lease))
139 packet.yiaddr = req_align; /* FIXME: oh my, is there a host using this IP? */
140 /* otherwise, find a free IP */
142 /* Is it a static lease? (No, because find_address skips static lease) */
143 packet.yiaddr = find_address(0);
144 /* try for an expired lease */
145 if (!packet.yiaddr) packet.yiaddr = find_address(1);
148 if (!packet.yiaddr) {
149 bb_error_msg("no IP addresses to give - OFFER abandoned");
152 if (!add_lease(packet.chaddr, packet.yiaddr, server_config.offer_time)) {
153 bb_error_msg("lease pool is full - OFFER abandoned");
156 lease_time = get_option(oldpacket, DHCP_LEASE_TIME);
158 memcpy(&lease_time_align, lease_time, 4);
159 lease_time_align = ntohl(lease_time_align);
160 if (lease_time_align > server_config.lease)
161 lease_time_align = server_config.lease;
164 /* Make sure we aren't just using the lease time from the previous offer */
165 if (lease_time_align < server_config.min_lease)
166 lease_time_align = server_config.lease;
167 /* ADDME: end of short circuit */
169 /* It is a static lease... use it */
170 packet.yiaddr = static_lease_ip;
173 add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
175 curr = server_config.options;
177 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
178 add_option_string(packet.options, curr->data);
182 add_bootp_options(&packet);
184 addr.s_addr = packet.yiaddr;
185 bb_info_msg("Sending OFFER of %s", inet_ntoa(addr));
186 return send_packet(&packet, 0);
190 int sendNAK(struct dhcpMessage *oldpacket)
192 struct dhcpMessage packet;
194 init_packet(&packet, oldpacket, DHCPNAK);
196 DEBUG("Sending NAK");
197 return send_packet(&packet, 1);
201 int sendACK(struct dhcpMessage *oldpacket, uint32_t yiaddr)
203 struct dhcpMessage packet;
204 struct option_set *curr;
206 uint32_t lease_time_align = server_config.lease;
209 init_packet(&packet, oldpacket, DHCPACK);
210 packet.yiaddr = yiaddr;
212 if ((lease_time = get_option(oldpacket, DHCP_LEASE_TIME))) {
213 memcpy(&lease_time_align, lease_time, 4);
214 lease_time_align = ntohl(lease_time_align);
215 if (lease_time_align > server_config.lease)
216 lease_time_align = server_config.lease;
217 else if (lease_time_align < server_config.min_lease)
218 lease_time_align = server_config.lease;
221 add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
223 curr = server_config.options;
225 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
226 add_option_string(packet.options, curr->data);
230 add_bootp_options(&packet);
232 addr.s_addr = packet.yiaddr;
233 bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
235 if (send_packet(&packet, 0) < 0)
238 add_lease(packet.chaddr, packet.yiaddr, lease_time_align);
244 int send_inform(struct dhcpMessage *oldpacket)
246 struct dhcpMessage packet;
247 struct option_set *curr;
249 init_packet(&packet, oldpacket, DHCPACK);
251 curr = server_config.options;
253 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
254 add_option_string(packet.options, curr->data);
258 add_bootp_options(&packet);
260 return send_packet(&packet, 0);