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);
47 message->htype = ARPHRD_ETHER;
48 message->hlen = ETHER_ADDR_LEN;
49 message->xid = htobe32(xid);
50 message->magic = htobe32(DHCP_MAGIC_COOKIE);
52 *opt = (uint8_t *)(message + 1);
54 err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1,
62 uint16_t dhcp_packet_checksum(void *buf, size_t len) {
63 uint64_t *buf_64 = buf;
64 uint64_t *end_64 = (uint64_t*)buf + (len / sizeof(uint64_t));
70 while (buf_64 < end_64) {
78 buf_32 = (uint32_t*)buf_64;
80 if (len & sizeof(uint32_t)) {
88 buf_16 = (uint16_t*)buf_32;
90 if (len & sizeof(uint16_t)) {
98 buf_8 = (uint8_t*)buf_16;
100 if (len & sizeof(uint8_t)) {
107 sum = (sum & 0xffff) + (sum >> 16);
112 void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr,
113 uint16_t source_port, be32_t destination_addr,
114 uint16_t destination_port, uint16_t len) {
115 packet->ip.version = IPVERSION;
116 packet->ip.ihl = DHCP_IP_SIZE / 4;
117 packet->ip.tot_len = htobe16(len);
119 packet->ip.tos = IPTOS_CLASS_CS6;
121 packet->ip.protocol = IPPROTO_UDP;
122 packet->ip.saddr = source_addr;
123 packet->ip.daddr = destination_addr;
125 packet->udp.source = htobe16(source_port);
126 packet->udp.dest = htobe16(destination_port);
128 packet->udp.len = htobe16(len - DHCP_IP_SIZE);
130 packet->ip.check = packet->udp.len;
131 packet->udp.check = dhcp_packet_checksum(&packet->ip.ttl, len - 8);
133 packet->ip.ttl = IPDEFTTL;
134 packet->ip.check = 0;
135 packet->ip.check = dhcp_packet_checksum(&packet->ip, DHCP_IP_SIZE);
138 int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum) {
145 if (packet->ip.version != IPVERSION) {
146 log_debug("ignoring packet: not IPv4");
150 if (packet->ip.ihl < 5) {
151 log_debug("ignoring packet: IPv4 IHL (%u words) invalid",
156 hdrlen = packet->ip.ihl * 4;
158 log_debug("ignoring packet: IPv4 IHL (%zu bytes) "
159 "smaller than minimum (20 bytes)", hdrlen);
164 log_debug("ignoring packet: packet (%zu bytes) "
165 "smaller than expected (%zu) by IP header", len,
172 if (packet->ip.protocol != IPPROTO_UDP) {
173 log_debug("ignoring packet: not UDP");
177 if (len < hdrlen + be16toh(packet->udp.len)) {
178 log_debug("ignoring packet: packet (%zu bytes) "
179 "smaller than expected (%zu) by UDP header", len,
180 hdrlen + be16toh(packet->udp.len));
184 if (be16toh(packet->udp.dest) != DHCP_PORT_CLIENT) {
185 log_debug("ignoring packet: to port %u, which "
186 "is not the DHCP client port (%u)",
187 be16toh(packet->udp.dest), DHCP_PORT_CLIENT);
191 /* checksums - computing these is relatively expensive, so only do it
192 if all the other checks have passed
195 if (dhcp_packet_checksum(&packet->ip, hdrlen)) {
196 log_debug("ignoring packet: invalid IP checksum");
200 if (checksum && packet->udp.check) {
201 packet->ip.check = packet->udp.len;
204 if (dhcp_packet_checksum(&packet->ip.ttl,
205 be16toh(packet->udp.len) + 12)) {
206 log_debug("ignoring packet: invalid UDP checksum");