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cf597f65 TG |
1 | /*** |
2 | This file is part of systemd. | |
3 | ||
4 | Copyright (C) 2013 Intel Corporation. All rights reserved. | |
5 | Copyright (C) 2014 Tom Gundersen | |
6 | ||
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. | |
11 | ||
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. | |
16 | ||
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/>. | |
19 | ***/ | |
20 | ||
21 | #include <stdlib.h> | |
22 | #include <errno.h> | |
23 | #include <string.h> | |
24 | #include <stdio.h> | |
25 | #include <net/ethernet.h> | |
26 | #include <net/if_arp.h> | |
27 | #include <sys/param.h> | |
28 | ||
29 | #include "util.h" | |
30 | #include "list.h" | |
31 | ||
32 | #include "dhcp-protocol.h" | |
fe8db0c5 | 33 | #include "dhcp-lease-internal.h" |
cf597f65 | 34 | #include "dhcp-internal.h" |
fe8db0c5 | 35 | #include "sd-dhcp-lease.h" |
cf597f65 TG |
36 | #include "sd-dhcp-client.h" |
37 | ||
38 | #define DHCP_CLIENT_MIN_OPTIONS_SIZE 312 | |
39 | ||
40 | int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid, | |
04b28be1 | 41 | uint8_t type, size_t optlen, size_t *optoffset) { |
20b958bf TG |
42 | size_t offset = 0; |
43 | int r; | |
cf597f65 | 44 | |
0a1b6da8 TG |
45 | assert(op == BOOTREQUEST || op == BOOTREPLY); |
46 | ||
cf597f65 TG |
47 | message->op = op; |
48 | message->htype = ARPHRD_ETHER; | |
49 | message->hlen = ETHER_ADDR_LEN; | |
50 | message->xid = htobe32(xid); | |
3b7ca119 | 51 | message->magic = htobe32(DHCP_MAGIC_COOKIE); |
cf597f65 | 52 | |
04b28be1 TG |
53 | r = dhcp_option_append(message, optlen, &offset, 0, |
54 | DHCP_OPTION_MESSAGE_TYPE, 1, &type); | |
20b958bf TG |
55 | if (r < 0) |
56 | return r; | |
cf597f65 | 57 | |
20b958bf | 58 | *optoffset = offset; |
cf597f65 TG |
59 | |
60 | return 0; | |
61 | } | |
62 | ||
d5761274 TG |
63 | uint16_t dhcp_packet_checksum(void *buf, size_t len) { |
64 | uint64_t *buf_64 = buf; | |
65 | uint64_t *end_64 = (uint64_t*)buf + (len / sizeof(uint64_t)); | |
66 | uint32_t *buf_32; | |
67 | uint16_t *buf_16; | |
68 | uint8_t *buf_8; | |
69 | uint64_t sum = 0; | |
70 | ||
71 | while (buf_64 < end_64) { | |
72 | sum += *buf_64; | |
73 | if (sum < *buf_64) | |
74 | sum++; | |
75 | ||
76 | buf_64 ++; | |
77 | } | |
78 | ||
79 | buf_32 = (uint32_t*)buf_64; | |
80 | ||
81 | if (len & sizeof(uint32_t)) { | |
82 | sum += *buf_32; | |
83 | if (sum < *buf_32) | |
84 | sum++; | |
85 | ||
86 | buf_32 ++; | |
87 | } | |
88 | ||
89 | buf_16 = (uint16_t*)buf_32; | |
cf597f65 | 90 | |
d5761274 TG |
91 | if (len & sizeof(uint16_t)) { |
92 | sum += *buf_16; | |
93 | if (sum < *buf_16) | |
94 | sum ++; | |
95 | ||
96 | buf_16 ++; | |
97 | } | |
cf597f65 | 98 | |
d5761274 | 99 | buf_8 = (uint8_t*)buf_16; |
cf597f65 | 100 | |
d5761274 TG |
101 | if (len & sizeof(uint8_t)) { |
102 | sum += *buf_8; | |
103 | if (sum < *buf_8) | |
104 | sum++; | |
cf597f65 TG |
105 | } |
106 | ||
107 | while (sum >> 16) | |
108 | sum = (sum & 0xffff) + (sum >> 16); | |
109 | ||
110 | return ~sum; | |
111 | } | |
112 | ||
63edaa62 TG |
113 | void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr, |
114 | uint16_t source_port, be32_t destination_addr, | |
115 | uint16_t destination_port, uint16_t len) { | |
cf597f65 TG |
116 | packet->ip.version = IPVERSION; |
117 | packet->ip.ihl = DHCP_IP_SIZE / 4; | |
118 | packet->ip.tot_len = htobe16(len); | |
119 | ||
85923f79 TG |
120 | packet->ip.tos = IPTOS_CLASS_CS6; |
121 | ||
cf597f65 | 122 | packet->ip.protocol = IPPROTO_UDP; |
63edaa62 TG |
123 | packet->ip.saddr = source_addr; |
124 | packet->ip.daddr = destination_addr; | |
cf597f65 | 125 | |
63edaa62 TG |
126 | packet->udp.source = htobe16(source_port); |
127 | packet->udp.dest = htobe16(destination_port); | |
cf597f65 TG |
128 | |
129 | packet->udp.len = htobe16(len - DHCP_IP_SIZE); | |
130 | ||
131 | packet->ip.check = packet->udp.len; | |
a838c939 | 132 | packet->udp.check = dhcp_packet_checksum(&packet->ip.ttl, len - 8); |
cf597f65 TG |
133 | |
134 | packet->ip.ttl = IPDEFTTL; | |
135 | packet->ip.check = 0; | |
a838c939 | 136 | packet->ip.check = dhcp_packet_checksum(&packet->ip, DHCP_IP_SIZE); |
cf597f65 TG |
137 | } |
138 | ||
55dab2ed | 139 | int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum) { |
cf597f65 TG |
140 | size_t hdrlen; |
141 | ||
5266a81e TG |
142 | assert(packet); |
143 | ||
06b44be7 | 144 | /* IP */ |
cf597f65 | 145 | |
6e34949d | 146 | if (packet->ip.version != IPVERSION) { |
aa6fc9b8 | 147 | log_debug("ignoring packet: not IPv4"); |
6e34949d TG |
148 | return -EINVAL; |
149 | } | |
150 | ||
06b44be7 | 151 | if (packet->ip.ihl < 5) { |
aa6fc9b8 TG |
152 | log_debug("ignoring packet: IPv4 IHL (%u words) invalid", |
153 | packet->ip.ihl); | |
cf597f65 | 154 | return -EINVAL; |
ac4f16ab | 155 | } |
cf597f65 TG |
156 | |
157 | hdrlen = packet->ip.ihl * 4; | |
06b44be7 | 158 | if (hdrlen < 20) { |
aa6fc9b8 TG |
159 | log_debug("ignoring packet: IPv4 IHL (%zu bytes) " |
160 | "smaller than minimum (20 bytes)", hdrlen); | |
06b44be7 TG |
161 | return -EINVAL; |
162 | } | |
163 | ||
164 | if (len < hdrlen) { | |
aa6fc9b8 TG |
165 | log_debug("ignoring packet: packet (%zu bytes) " |
166 | "smaller than expected (%zu) by IP header", len, | |
167 | hdrlen); | |
cf597f65 | 168 | return -EINVAL; |
ac4f16ab | 169 | } |
cf597f65 | 170 | |
06b44be7 TG |
171 | /* UDP */ |
172 | ||
d454a674 | 173 | if (packet->ip.protocol != IPPROTO_UDP) { |
aa6fc9b8 | 174 | log_debug("ignoring packet: not UDP"); |
d454a674 UTL |
175 | return -EINVAL; |
176 | } | |
177 | ||
8fa2eeac | 178 | if (len < hdrlen + be16toh(packet->udp.len)) { |
aa6fc9b8 TG |
179 | log_debug("ignoring packet: packet (%zu bytes) " |
180 | "smaller than expected (%zu) by UDP header", len, | |
181 | hdrlen + be16toh(packet->udp.len)); | |
ac4f16ab TG |
182 | return -EINVAL; |
183 | } | |
cf597f65 | 184 | |
2ad7561f | 185 | if (be16toh(packet->udp.dest) != DHCP_PORT_CLIENT) { |
aa6fc9b8 TG |
186 | log_debug("ignoring packet: to port %u, which " |
187 | "is not the DHCP client port (%u)", | |
188 | be16toh(packet->udp.dest), DHCP_PORT_CLIENT); | |
2ad7561f TG |
189 | return -EINVAL; |
190 | } | |
191 | ||
192 | /* checksums - computing these is relatively expensive, so only do it | |
193 | if all the other checks have passed | |
194 | */ | |
195 | ||
196 | if (dhcp_packet_checksum(&packet->ip, hdrlen)) { | |
aa6fc9b8 | 197 | log_debug("ignoring packet: invalid IP checksum"); |
2ad7561f TG |
198 | return -EINVAL; |
199 | } | |
200 | ||
55dab2ed | 201 | if (checksum && packet->udp.check) { |
cf597f65 TG |
202 | packet->ip.check = packet->udp.len; |
203 | packet->ip.ttl = 0; | |
204 | ||
a838c939 | 205 | if (dhcp_packet_checksum(&packet->ip.ttl, |
ac4f16ab | 206 | be16toh(packet->udp.len) + 12)) { |
aa6fc9b8 | 207 | log_debug("ignoring packet: invalid UDP checksum"); |
cf597f65 | 208 | return -EINVAL; |
ac4f16ab | 209 | } |
cf597f65 TG |
210 | } |
211 | ||
cf597f65 TG |
212 | return 0; |
213 | } |