[1765] | 1 | /* vi: set sw=4 ts=4: */
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[821] | 2 | /* serverpacket.c
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| 3 | *
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| 4 | * Construct and send DHCP server packets
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| 5 | *
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| 6 | * Russ Dill <Russ.Dill@asu.edu> July 2001
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| 7 | *
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| 8 | * This program is free software; you can redistribute it and/or modify
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| 9 | * it under the terms of the GNU General Public License as published by
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| 10 | * the Free Software Foundation; either version 2 of the License, or
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| 11 | * (at your option) any later version.
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| 12 | *
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| 13 | * This program is distributed in the hope that it will be useful,
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| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 16 | * GNU General Public License for more details.
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| 17 | *
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| 18 | * You should have received a copy of the GNU General Public License
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| 19 | * along with this program; if not, write to the Free Software
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| 20 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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| 21 | */
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| 22 |
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| 23 | #include "common.h"
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| 24 | #include "dhcpd.h"
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| 25 | #include "options.h"
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| 26 |
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[1765] | 27 |
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[821] | 28 | /* send a packet to giaddr using the kernel ip stack */
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| 29 | static int send_packet_to_relay(struct dhcpMessage *payload)
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| 30 | {
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[1765] | 31 | DEBUG("Forwarding packet to relay");
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[821] | 32 |
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| 33 | return udhcp_kernel_packet(payload, server_config.server, SERVER_PORT,
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| 34 | payload->giaddr, SERVER_PORT);
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| 35 | }
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| 36 |
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| 37 |
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| 38 | /* send a packet to a specific arp address and ip address by creating our own ip packet */
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| 39 | static int send_packet_to_client(struct dhcpMessage *payload, int force_broadcast)
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| 40 | {
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[1765] | 41 | const uint8_t *chaddr;
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[821] | 42 | uint32_t ciaddr;
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| 43 |
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| 44 | if (force_broadcast) {
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[1765] | 45 | DEBUG("broadcasting packet to client (NAK)");
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[821] | 46 | ciaddr = INADDR_BROADCAST;
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| 47 | chaddr = MAC_BCAST_ADDR;
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| 48 | } else if (payload->ciaddr) {
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[1765] | 49 | DEBUG("unicasting packet to client ciaddr");
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[821] | 50 | ciaddr = payload->ciaddr;
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| 51 | chaddr = payload->chaddr;
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| 52 | } else if (ntohs(payload->flags) & BROADCAST_FLAG) {
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[1765] | 53 | DEBUG("broadcasting packet to client (requested)");
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[821] | 54 | ciaddr = INADDR_BROADCAST;
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| 55 | chaddr = MAC_BCAST_ADDR;
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| 56 | } else {
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[1765] | 57 | DEBUG("unicasting packet to client yiaddr");
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[821] | 58 | ciaddr = payload->yiaddr;
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| 59 | chaddr = payload->chaddr;
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| 60 | }
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| 61 | return udhcp_raw_packet(payload, server_config.server, SERVER_PORT,
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| 62 | ciaddr, CLIENT_PORT, chaddr, server_config.ifindex);
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| 63 | }
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| 64 |
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| 65 |
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| 66 | /* send a dhcp packet, if force broadcast is set, the packet will be broadcast to the client */
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| 67 | static int send_packet(struct dhcpMessage *payload, int force_broadcast)
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| 68 | {
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| 69 | int ret;
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| 70 |
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| 71 | if (payload->giaddr)
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| 72 | ret = send_packet_to_relay(payload);
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| 73 | else ret = send_packet_to_client(payload, force_broadcast);
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| 74 | return ret;
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| 75 | }
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| 76 |
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| 77 |
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| 78 | static void init_packet(struct dhcpMessage *packet, struct dhcpMessage *oldpacket, char type)
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| 79 | {
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| 80 | udhcp_init_header(packet, type);
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| 81 | packet->xid = oldpacket->xid;
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| 82 | memcpy(packet->chaddr, oldpacket->chaddr, 16);
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| 83 | packet->flags = oldpacket->flags;
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| 84 | packet->giaddr = oldpacket->giaddr;
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| 85 | packet->ciaddr = oldpacket->ciaddr;
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| 86 | add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server);
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| 87 | }
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| 88 |
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| 89 |
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| 90 | /* add in the bootp options */
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| 91 | static void add_bootp_options(struct dhcpMessage *packet)
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| 92 | {
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| 93 | packet->siaddr = server_config.siaddr;
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| 94 | if (server_config.sname)
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| 95 | strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1);
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| 96 | if (server_config.boot_file)
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| 97 | strncpy((char*)packet->file, server_config.boot_file, sizeof(packet->file) - 1);
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| 98 | }
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| 99 |
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| 100 |
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| 101 | /* send a DHCP OFFER to a DHCP DISCOVER */
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| 102 | int sendOffer(struct dhcpMessage *oldpacket)
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| 103 | {
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| 104 | struct dhcpMessage packet;
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| 105 | struct dhcpOfferedAddr *lease = NULL;
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| 106 | uint32_t req_align, lease_time_align = server_config.lease;
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| 107 | uint8_t *req, *lease_time;
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| 108 | struct option_set *curr;
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| 109 | struct in_addr addr;
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| 110 |
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| 111 | uint32_t static_lease_ip;
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| 112 |
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| 113 | init_packet(&packet, oldpacket, DHCPOFFER);
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| 114 |
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| 115 | static_lease_ip = getIpByMac(server_config.static_leases, oldpacket->chaddr);
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| 116 |
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| 117 | /* ADDME: if static, short circuit */
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[1765] | 118 | if (!static_lease_ip) {
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| 119 | /* the client is in our lease/offered table */
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| 120 | lease = find_lease_by_chaddr(oldpacket->chaddr);
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| 121 | if (lease) {
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| 122 | if (!lease_expired(lease))
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| 123 | lease_time_align = lease->expires - time(0);
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| 124 | packet.yiaddr = lease->yiaddr;
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| 125 | /* Or the client has a requested ip */
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| 126 | } else if ((req = get_option(oldpacket, DHCP_REQUESTED_IP))
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| 127 | /* Don't look here (ugly hackish thing to do) */
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| 128 | && memcpy(&req_align, req, 4)
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| 129 | /* and the ip is in the lease range */
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| 130 | && ntohl(req_align) >= server_config.start_ip
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| 131 | && ntohl(req_align) <= server_config.end_ip
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| 132 | && !static_lease_ip /* Check that its not a static lease */
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| 133 | /* and is not already taken/offered */
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| 134 | && (!(lease = find_lease_by_yiaddr(req_align))
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| 135 | /* or its taken, but expired */ /* ADDME: or maybe in here */
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| 136 | || lease_expired(lease))
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| 137 | ) {
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| 138 | packet.yiaddr = req_align; /* FIXME: oh my, is there a host using this IP? */
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[821] | 139 | /* otherwise, find a free IP */
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[1765] | 140 | } else {
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[821] | 141 | /* Is it a static lease? (No, because find_address skips static lease) */
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[1765] | 142 | packet.yiaddr = find_address(0);
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| 143 | /* try for an expired lease */
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| 144 | if (!packet.yiaddr)
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| 145 | packet.yiaddr = find_address(1);
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| 146 | }
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[821] | 147 |
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[1765] | 148 | if (!packet.yiaddr) {
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| 149 | bb_error_msg("no IP addresses to give - OFFER abandoned");
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| 150 | return -1;
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| 151 | }
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| 152 | if (!add_lease(packet.chaddr, packet.yiaddr, server_config.offer_time)) {
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| 153 | bb_error_msg("lease pool is full - OFFER abandoned");
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| 154 | return -1;
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| 155 | }
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| 156 | lease_time = get_option(oldpacket, DHCP_LEASE_TIME);
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| 157 | if (lease_time) {
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| 158 | memcpy(&lease_time_align, lease_time, 4);
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| 159 | lease_time_align = ntohl(lease_time_align);
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| 160 | if (lease_time_align > server_config.lease)
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| 161 | lease_time_align = server_config.lease;
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| 162 | }
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[821] | 163 |
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[1765] | 164 | /* Make sure we aren't just using the lease time from the previous offer */
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| 165 | if (lease_time_align < server_config.min_lease)
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[821] | 166 | lease_time_align = server_config.lease;
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[1765] | 167 | /* ADDME: end of short circuit */
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| 168 | } else {
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[821] | 169 | /* It is a static lease... use it */
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| 170 | packet.yiaddr = static_lease_ip;
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| 171 | }
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| 172 |
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| 173 | add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
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| 174 |
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| 175 | curr = server_config.options;
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| 176 | while (curr) {
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| 177 | if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
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| 178 | add_option_string(packet.options, curr->data);
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| 179 | curr = curr->next;
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| 180 | }
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| 181 |
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| 182 | add_bootp_options(&packet);
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| 183 |
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| 184 | addr.s_addr = packet.yiaddr;
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[1765] | 185 | bb_info_msg("Sending OFFER of %s", inet_ntoa(addr));
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[821] | 186 | return send_packet(&packet, 0);
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| 187 | }
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| 188 |
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| 189 |
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| 190 | int sendNAK(struct dhcpMessage *oldpacket)
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| 191 | {
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| 192 | struct dhcpMessage packet;
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| 193 |
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| 194 | init_packet(&packet, oldpacket, DHCPNAK);
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| 195 |
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[1765] | 196 | DEBUG("Sending NAK");
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[821] | 197 | return send_packet(&packet, 1);
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| 198 | }
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| 199 |
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| 200 |
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| 201 | int sendACK(struct dhcpMessage *oldpacket, uint32_t yiaddr)
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| 202 | {
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| 203 | struct dhcpMessage packet;
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| 204 | struct option_set *curr;
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| 205 | uint8_t *lease_time;
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| 206 | uint32_t lease_time_align = server_config.lease;
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| 207 | struct in_addr addr;
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| 208 |
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| 209 | init_packet(&packet, oldpacket, DHCPACK);
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| 210 | packet.yiaddr = yiaddr;
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| 211 |
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[1765] | 212 | lease_time = get_option(oldpacket, DHCP_LEASE_TIME);
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| 213 | if (lease_time) {
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[821] | 214 | memcpy(&lease_time_align, lease_time, 4);
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| 215 | lease_time_align = ntohl(lease_time_align);
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| 216 | if (lease_time_align > server_config.lease)
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| 217 | lease_time_align = server_config.lease;
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| 218 | else if (lease_time_align < server_config.min_lease)
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| 219 | lease_time_align = server_config.lease;
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| 220 | }
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| 221 |
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| 222 | add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
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| 223 |
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| 224 | curr = server_config.options;
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| 225 | while (curr) {
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| 226 | if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
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| 227 | add_option_string(packet.options, curr->data);
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| 228 | curr = curr->next;
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| 229 | }
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| 230 |
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| 231 | add_bootp_options(&packet);
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| 232 |
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| 233 | addr.s_addr = packet.yiaddr;
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[1765] | 234 | bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
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[821] | 235 |
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| 236 | if (send_packet(&packet, 0) < 0)
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| 237 | return -1;
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| 238 |
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| 239 | add_lease(packet.chaddr, packet.yiaddr, lease_time_align);
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[1765] | 240 | if (ENABLE_FEATURE_UDHCPD_WRITE_LEASES_EARLY) {
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| 241 | /* rewrite the file with leases at every new acceptance */
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| 242 | write_leases();
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| 243 | }
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[821] | 244 |
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| 245 | return 0;
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| 246 | }
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| 247 |
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| 248 |
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| 249 | int send_inform(struct dhcpMessage *oldpacket)
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| 250 | {
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| 251 | struct dhcpMessage packet;
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| 252 | struct option_set *curr;
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| 253 |
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| 254 | init_packet(&packet, oldpacket, DHCPACK);
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| 255 |
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| 256 | curr = server_config.options;
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| 257 | while (curr) {
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| 258 | if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
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| 259 | add_option_string(packet.options, curr->data);
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| 260 | curr = curr->next;
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| 261 | }
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| 262 |
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| 263 | add_bootp_options(&packet);
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| 264 |
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| 265 | return send_packet(&packet, 0);
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| 266 | }
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