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