2 This file is part of systemd.
4 Copyright (C) 2013 Intel Corporation. All rights reserved.
5 Copyright (C) 2014 Tom Gundersen
7 systemd is free software; you can redistribute it and/or modify it
8 under the terms of the GNU Lesser General Public License as published by
9 the Free Software Foundation; either version 2.1 of the License, or
10 (at your option) any later version.
12 systemd is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public License
18 along with systemd; If not, see <http://www.gnu.org/licenses/>.
25 #include <net/ethernet.h>
26 #include <net/if_arp.h>
27 #include <sys/param.h>
32 #include "dhcp-protocol.h"
33 #include "dhcp-lease-internal.h"
34 #include "dhcp-internal.h"
35 #include "sd-dhcp-lease.h"
36 #include "sd-dhcp-client.h"
38 #define DHCP_CLIENT_MIN_OPTIONS_SIZE 312
40 int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid,
41 uint8_t type, uint8_t **opt, size_t *optlen) {
44 assert(op == BOOTREQUEST || op == BOOTREPLY);
46 *opt = (uint8_t *)(message + 1);
53 message->htype = ARPHRD_ETHER;
54 message->hlen = ETHER_ADDR_LEN;
55 message->xid = htobe32(xid);
64 err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1,
72 uint16_t dhcp_packet_checksum(void *buf, int len) {
81 for (i = 0; i < len / 2 ; i++)
90 sum = (sum & 0xffff) + (sum >> 16);
95 void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr,
96 uint16_t source_port, be32_t destination_addr,
97 uint16_t destination_port, uint16_t len) {
98 packet->ip.version = IPVERSION;
99 packet->ip.ihl = DHCP_IP_SIZE / 4;
100 packet->ip.tot_len = htobe16(len);
102 packet->ip.protocol = IPPROTO_UDP;
103 packet->ip.saddr = source_addr;
104 packet->ip.daddr = destination_addr;
106 packet->udp.source = htobe16(source_port);
107 packet->udp.dest = htobe16(destination_port);
109 packet->udp.len = htobe16(len - DHCP_IP_SIZE);
111 packet->ip.check = packet->udp.len;
112 packet->udp.check = dhcp_packet_checksum(&packet->ip.ttl, len - 8);
114 packet->ip.ttl = IPDEFTTL;
115 packet->ip.check = 0;
116 packet->ip.check = dhcp_packet_checksum(&packet->ip, DHCP_IP_SIZE);
119 int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum) {
126 if (len < DHCP_IP_SIZE) {
127 log_dhcp_client(client, "ignoring packet: packet (%zu bytes) "
128 " smaller than IP header (%u bytes)", len,
133 if (packet->ip.version != IPVERSION) {
134 log_dhcp_client(client, "ignoring packet: not IPv4");
138 if (packet->ip.ihl < 5) {
139 log_dhcp_client(client, "ignoring packet: IPv4 IHL (%u words) invalid",
144 hdrlen = packet->ip.ihl * 4;
146 log_dhcp_client(client, "ignoring packet: IPv4 IHL (%zu bytes) "
147 "smaller than minimum (20 bytes)", hdrlen);
152 log_dhcp_client(client, "ignoring packet: packet (%zu bytes) "
153 "smaller than expected (%zu) by IP header", len,
160 if (packet->ip.protocol != IPPROTO_UDP) {
161 log_dhcp_client(client, "ignoring packet: not UDP");
165 if (len < DHCP_IP_UDP_SIZE) {
166 log_dhcp_client(client, "ignoring packet: packet (%zu bytes) "
167 " smaller than IP+UDP header (%u bytes)", len,
172 if (len < hdrlen + be16toh(packet->udp.len)) {
173 log_dhcp_client(client, "ignoring packet: packet (%zu bytes) "
174 "smaller than expected (%zu) by UDP header", len,
175 hdrlen + be16toh(packet->udp.len));
179 if (be16toh(packet->udp.dest) != DHCP_PORT_CLIENT) {
180 log_dhcp_client(client, "ignoring packet: to port %u, which "
181 "is not the DHCP client port (%u)",
182 be16toh(packet->udp.dest), DHCP_PORT_CLIENT);
186 /* checksums - computing these is relatively expensive, so only do it
187 if all the other checks have passed
190 if (dhcp_packet_checksum(&packet->ip, hdrlen)) {
191 log_dhcp_client(client, "ignoring packet: invalid IP checksum");
195 if (checksum && packet->udp.check) {
196 packet->ip.check = packet->udp.len;
199 if (dhcp_packet_checksum(&packet->ip.ttl,
200 be16toh(packet->udp.len) + 12)) {
201 log_dhcp_client(client, "ignoring packet: invalid UDP checksum");