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db9ecf05 | 1 | /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
cf597f65 | 2 | /*** |
810adae9 | 3 | Copyright © 2013 Intel Corporation. All rights reserved. |
cf597f65 TG |
4 | ***/ |
5 | ||
cf597f65 | 6 | #include <errno.h> |
cf597f65 TG |
7 | #include <net/ethernet.h> |
8 | #include <net/if_arp.h> | |
cf0fbc49 | 9 | #include <string.h> |
cf597f65 | 10 | |
8664ded7 YW |
11 | #include "dhcp-option.h" |
12 | #include "dhcp-packet.h" | |
97fa338d | 13 | #include "memory-util.h" |
cf597f65 TG |
14 | |
15 | #define DHCP_CLIENT_MIN_OPTIONS_SIZE 312 | |
16 | ||
97fa338d YW |
17 | int dhcp_message_init( |
18 | DHCPMessage *message, | |
19 | uint8_t op, | |
20 | uint32_t xid, | |
21 | uint8_t type, | |
22 | uint16_t arp_type, | |
23 | uint8_t hlen, | |
24 | const uint8_t *chaddr, | |
25 | size_t optlen, | |
26 | size_t *optoffset) { | |
27 | ||
20b958bf TG |
28 | size_t offset = 0; |
29 | int r; | |
cf597f65 | 30 | |
3742095b | 31 | assert(IN_SET(op, BOOTREQUEST, BOOTREPLY)); |
97fa338d | 32 | assert(chaddr || hlen == 0); |
0a1b6da8 | 33 | |
cf597f65 | 34 | message->op = op; |
76253e73 | 35 | message->htype = arp_type; |
97fa338d YW |
36 | |
37 | /* RFC2131 section 4.1.1: | |
38 | The client MUST include its hardware address in the ’chaddr’ field, if | |
39 | necessary for delivery of DHCP reply messages. | |
40 | ||
41 | RFC 4390 section 2.1: | |
42 | A DHCP client, when working over an IPoIB interface, MUST follow the | |
43 | following rules: | |
44 | "htype" (hardware address type) MUST be 32 [ARPPARAM]. | |
45 | "hlen" (hardware address length) MUST be 0. | |
46 | "chaddr" (client hardware address) field MUST be zeroed. | |
47 | */ | |
0b6a4795 | 48 | message->hlen = arp_type == ARPHRD_INFINIBAND ? 0 : hlen; |
97fa338d YW |
49 | memcpy_safe(message->chaddr, chaddr, message->hlen); |
50 | ||
cf597f65 | 51 | message->xid = htobe32(xid); |
3b7ca119 | 52 | message->magic = htobe32(DHCP_MAGIC_COOKIE); |
cf597f65 | 53 | |
04b28be1 | 54 | r = dhcp_option_append(message, optlen, &offset, 0, |
22805d92 | 55 | SD_DHCP_OPTION_MESSAGE_TYPE, 1, &type); |
20b958bf TG |
56 | if (r < 0) |
57 | return r; | |
cf597f65 | 58 | |
20b958bf | 59 | *optoffset = offset; |
cf597f65 TG |
60 | |
61 | return 0; | |
62 | } | |
63 | ||
0bbc2c1f TG |
64 | uint16_t dhcp_packet_checksum(uint8_t *buf, size_t len) { |
65 | uint64_t *buf_64 = (uint64_t*)buf; | |
66 | uint64_t *end_64 = buf_64 + (len / sizeof(uint64_t)); | |
d5761274 TG |
67 | uint64_t sum = 0; |
68 | ||
0bbc2c1f TG |
69 | /* See RFC1071 */ |
70 | ||
d5761274 TG |
71 | while (buf_64 < end_64) { |
72 | sum += *buf_64; | |
73 | if (sum < *buf_64) | |
0bbc2c1f | 74 | /* wrap around in one's complement */ |
d5761274 TG |
75 | sum++; |
76 | ||
313cefa1 | 77 | buf_64++; |
d5761274 TG |
78 | } |
79 | ||
0bbc2c1f TG |
80 | if (len % sizeof(uint64_t)) { |
81 | /* If the buffer is not aligned to 64-bit, we need | |
82 | to zero-pad the last few bytes and add them in */ | |
83 | uint64_t buf_tail = 0; | |
cf597f65 | 84 | |
0bbc2c1f | 85 | memcpy(&buf_tail, buf_64, len % sizeof(uint64_t)); |
cf597f65 | 86 | |
0bbc2c1f TG |
87 | sum += buf_tail; |
88 | if (sum < buf_tail) | |
89 | /* wrap around */ | |
d5761274 | 90 | sum++; |
cf597f65 TG |
91 | } |
92 | ||
93 | while (sum >> 16) | |
94 | sum = (sum & 0xffff) + (sum >> 16); | |
95 | ||
96 | return ~sum; | |
97 | } | |
98 | ||
63edaa62 TG |
99 | void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr, |
100 | uint16_t source_port, be32_t destination_addr, | |
afe42aef | 101 | uint16_t destination_port, uint16_t len, int ip_service_type) { |
cf597f65 TG |
102 | packet->ip.version = IPVERSION; |
103 | packet->ip.ihl = DHCP_IP_SIZE / 4; | |
104 | packet->ip.tot_len = htobe16(len); | |
105 | ||
afe42aef SC |
106 | if (ip_service_type >= 0) |
107 | packet->ip.tos = ip_service_type; | |
108 | else | |
109 | packet->ip.tos = IPTOS_CLASS_CS6; | |
85923f79 | 110 | |
cf597f65 | 111 | packet->ip.protocol = IPPROTO_UDP; |
63edaa62 TG |
112 | packet->ip.saddr = source_addr; |
113 | packet->ip.daddr = destination_addr; | |
cf597f65 | 114 | |
63edaa62 TG |
115 | packet->udp.source = htobe16(source_port); |
116 | packet->udp.dest = htobe16(destination_port); | |
cf597f65 TG |
117 | |
118 | packet->udp.len = htobe16(len - DHCP_IP_SIZE); | |
119 | ||
120 | packet->ip.check = packet->udp.len; | |
0bbc2c1f | 121 | packet->udp.check = dhcp_packet_checksum((uint8_t*)&packet->ip.ttl, len - 8); |
cf597f65 TG |
122 | |
123 | packet->ip.ttl = IPDEFTTL; | |
124 | packet->ip.check = 0; | |
0bbc2c1f | 125 | packet->ip.check = dhcp_packet_checksum((uint8_t*)&packet->ip, DHCP_IP_SIZE); |
cf597f65 TG |
126 | } |
127 | ||
9faed222 | 128 | int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum, uint16_t port) { |
cf597f65 TG |
129 | size_t hdrlen; |
130 | ||
5266a81e | 131 | assert(packet); |
a57dd1d1 YW |
132 | |
133 | if (len < sizeof(DHCPPacket)) | |
134 | return 0; | |
5266a81e | 135 | |
06b44be7 | 136 | /* IP */ |
cf597f65 | 137 | |
baaa35ad ZJS |
138 | if (packet->ip.version != IPVERSION) |
139 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
140 | "ignoring packet: not IPv4"); | |
6e34949d | 141 | |
baaa35ad ZJS |
142 | if (packet->ip.ihl < 5) |
143 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
c0f86d66 | 144 | "ignoring packet: IPv4 IHL (%i words) invalid", |
baaa35ad | 145 | packet->ip.ihl); |
cf597f65 TG |
146 | |
147 | hdrlen = packet->ip.ihl * 4; | |
baaa35ad ZJS |
148 | if (hdrlen < 20) |
149 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
9a94baa6 | 150 | "ignoring packet: IPv4 IHL (%zu bytes) smaller than minimum (20 bytes)", |
baaa35ad ZJS |
151 | hdrlen); |
152 | ||
153 | if (len < hdrlen) | |
154 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
9a94baa6 | 155 | "ignoring packet: packet (%zu bytes) smaller than expected (%zu) by IP header", |
baaa35ad | 156 | len, hdrlen); |
cf597f65 | 157 | |
06b44be7 TG |
158 | /* UDP */ |
159 | ||
baaa35ad ZJS |
160 | if (packet->ip.protocol != IPPROTO_UDP) |
161 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
162 | "ignoring packet: not UDP"); | |
d454a674 | 163 | |
baaa35ad ZJS |
164 | if (len < hdrlen + be16toh(packet->udp.len)) |
165 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
9a94baa6 | 166 | "ignoring packet: packet (%zu bytes) smaller than expected (%zu) by UDP header", |
baaa35ad | 167 | len, hdrlen + be16toh(packet->udp.len)); |
cf597f65 | 168 | |
baaa35ad ZJS |
169 | if (be16toh(packet->udp.dest) != port) |
170 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
9a94baa6 | 171 | "ignoring packet: to port %u, which is not the DHCP client port (%u)", |
baaa35ad | 172 | be16toh(packet->udp.dest), port); |
2ad7561f TG |
173 | |
174 | /* checksums - computing these is relatively expensive, so only do it | |
175 | if all the other checks have passed | |
176 | */ | |
177 | ||
baaa35ad ZJS |
178 | if (dhcp_packet_checksum((uint8_t*)&packet->ip, hdrlen)) |
179 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
180 | "ignoring packet: invalid IP checksum"); | |
2ad7561f | 181 | |
55dab2ed | 182 | if (checksum && packet->udp.check) { |
cf597f65 TG |
183 | packet->ip.check = packet->udp.len; |
184 | packet->ip.ttl = 0; | |
185 | ||
0bbc2c1f | 186 | if (dhcp_packet_checksum((uint8_t*)&packet->ip.ttl, |
baaa35ad ZJS |
187 | be16toh(packet->udp.len) + 12)) |
188 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
189 | "ignoring packet: invalid UDP checksum"); | |
cf597f65 TG |
190 | } |
191 | ||
cf597f65 TG |
192 | return 0; |
193 | } |