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, uint16_t arp_type, size_t optlen,
46 assert(op == BOOTREQUEST || op == BOOTREPLY);
47 assert(arp_type == ARPHRD_ETHER || arp_type == ARPHRD_INFINIBAND);
50 message->htype = arp_type;
51 message->hlen = (arp_type == ARPHRD_ETHER) ? ETHER_ADDR_LEN : 0;
52 message->xid = htobe32(xid);
53 message->magic = htobe32(DHCP_MAGIC_COOKIE);
55 r = dhcp_option_append(message, optlen, &offset, 0,
56 DHCP_OPTION_MESSAGE_TYPE, 1, &type);
65 uint16_t dhcp_packet_checksum(uint8_t *buf, size_t len) {
66 uint64_t *buf_64 = (uint64_t*)buf;
67 uint64_t *end_64 = buf_64 + (len / sizeof(uint64_t));
72 while (buf_64 < end_64) {
75 /* wrap around in one's complement */
81 if (len % sizeof(uint64_t)) {
82 /* If the buffer is not aligned to 64-bit, we need
83 to zero-pad the last few bytes and add them in */
84 uint64_t buf_tail = 0;
86 memcpy(&buf_tail, buf_64, len % sizeof(uint64_t));
95 sum = (sum & 0xffff) + (sum >> 16);
100 void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr,
101 uint16_t source_port, be32_t destination_addr,
102 uint16_t destination_port, uint16_t len) {
103 packet->ip.version = IPVERSION;
104 packet->ip.ihl = DHCP_IP_SIZE / 4;
105 packet->ip.tot_len = htobe16(len);
107 packet->ip.tos = IPTOS_CLASS_CS6;
109 packet->ip.protocol = IPPROTO_UDP;
110 packet->ip.saddr = source_addr;
111 packet->ip.daddr = destination_addr;
113 packet->udp.source = htobe16(source_port);
114 packet->udp.dest = htobe16(destination_port);
116 packet->udp.len = htobe16(len - DHCP_IP_SIZE);
118 packet->ip.check = packet->udp.len;
119 packet->udp.check = dhcp_packet_checksum((uint8_t*)&packet->ip.ttl, len - 8);
121 packet->ip.ttl = IPDEFTTL;
122 packet->ip.check = 0;
123 packet->ip.check = dhcp_packet_checksum((uint8_t*)&packet->ip, DHCP_IP_SIZE);
126 int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum) {
133 if (packet->ip.version != IPVERSION) {
134 log_debug("ignoring packet: not IPv4");
138 if (packet->ip.ihl < 5) {
139 log_debug("ignoring packet: IPv4 IHL (%u words) invalid",
144 hdrlen = packet->ip.ihl * 4;
146 log_debug("ignoring packet: IPv4 IHL (%zu bytes) "
147 "smaller than minimum (20 bytes)", hdrlen);
152 log_debug("ignoring packet: packet (%zu bytes) "
153 "smaller than expected (%zu) by IP header", len,
160 if (packet->ip.protocol != IPPROTO_UDP) {
161 log_debug("ignoring packet: not UDP");
165 if (len < hdrlen + be16toh(packet->udp.len)) {
166 log_debug("ignoring packet: packet (%zu bytes) "
167 "smaller than expected (%zu) by UDP header", len,
168 hdrlen + be16toh(packet->udp.len));
172 if (be16toh(packet->udp.dest) != DHCP_PORT_CLIENT) {
173 log_debug("ignoring packet: to port %u, which "
174 "is not the DHCP client port (%u)",
175 be16toh(packet->udp.dest), DHCP_PORT_CLIENT);
179 /* checksums - computing these is relatively expensive, so only do it
180 if all the other checks have passed
183 if (dhcp_packet_checksum((uint8_t*)&packet->ip, hdrlen)) {
184 log_debug("ignoring packet: invalid IP checksum");
188 if (checksum && packet->udp.check) {
189 packet->ip.check = packet->udp.len;
192 if (dhcp_packet_checksum((uint8_t*)&packet->ip.ttl,
193 be16toh(packet->udp.len) + 12)) {
194 log_debug("ignoring packet: invalid UDP checksum");