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Commit | Line | Data |
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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
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 | |
cf597f65 | 11 | #include "dhcp-internal.h" |
cf0fbc49 | 12 | #include "dhcp-protocol.h" |
cf597f65 TG |
13 | |
14 | #define DHCP_CLIENT_MIN_OPTIONS_SIZE 312 | |
15 | ||
16 | int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid, | |
76253e73 DW |
17 | uint8_t type, uint16_t arp_type, size_t optlen, |
18 | size_t *optoffset) { | |
20b958bf TG |
19 | size_t offset = 0; |
20 | int r; | |
cf597f65 | 21 | |
3742095b AR |
22 | assert(IN_SET(op, BOOTREQUEST, BOOTREPLY)); |
23 | assert(IN_SET(arp_type, ARPHRD_ETHER, ARPHRD_INFINIBAND)); | |
0a1b6da8 | 24 | |
cf597f65 | 25 | message->op = op; |
76253e73 DW |
26 | message->htype = arp_type; |
27 | message->hlen = (arp_type == ARPHRD_ETHER) ? ETHER_ADDR_LEN : 0; | |
cf597f65 | 28 | message->xid = htobe32(xid); |
3b7ca119 | 29 | message->magic = htobe32(DHCP_MAGIC_COOKIE); |
cf597f65 | 30 | |
04b28be1 | 31 | r = dhcp_option_append(message, optlen, &offset, 0, |
22805d92 | 32 | SD_DHCP_OPTION_MESSAGE_TYPE, 1, &type); |
20b958bf TG |
33 | if (r < 0) |
34 | return r; | |
cf597f65 | 35 | |
20b958bf | 36 | *optoffset = offset; |
cf597f65 TG |
37 | |
38 | return 0; | |
39 | } | |
40 | ||
0bbc2c1f TG |
41 | uint16_t dhcp_packet_checksum(uint8_t *buf, size_t len) { |
42 | uint64_t *buf_64 = (uint64_t*)buf; | |
43 | uint64_t *end_64 = buf_64 + (len / sizeof(uint64_t)); | |
d5761274 TG |
44 | uint64_t sum = 0; |
45 | ||
0bbc2c1f TG |
46 | /* See RFC1071 */ |
47 | ||
d5761274 TG |
48 | while (buf_64 < end_64) { |
49 | sum += *buf_64; | |
50 | if (sum < *buf_64) | |
0bbc2c1f | 51 | /* wrap around in one's complement */ |
d5761274 TG |
52 | sum++; |
53 | ||
313cefa1 | 54 | buf_64++; |
d5761274 TG |
55 | } |
56 | ||
0bbc2c1f TG |
57 | if (len % sizeof(uint64_t)) { |
58 | /* If the buffer is not aligned to 64-bit, we need | |
59 | to zero-pad the last few bytes and add them in */ | |
60 | uint64_t buf_tail = 0; | |
cf597f65 | 61 | |
0bbc2c1f | 62 | memcpy(&buf_tail, buf_64, len % sizeof(uint64_t)); |
cf597f65 | 63 | |
0bbc2c1f TG |
64 | sum += buf_tail; |
65 | if (sum < buf_tail) | |
66 | /* wrap around */ | |
d5761274 | 67 | sum++; |
cf597f65 TG |
68 | } |
69 | ||
70 | while (sum >> 16) | |
71 | sum = (sum & 0xffff) + (sum >> 16); | |
72 | ||
73 | return ~sum; | |
74 | } | |
75 | ||
63edaa62 TG |
76 | void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr, |
77 | uint16_t source_port, be32_t destination_addr, | |
78 | uint16_t destination_port, uint16_t len) { | |
cf597f65 TG |
79 | packet->ip.version = IPVERSION; |
80 | packet->ip.ihl = DHCP_IP_SIZE / 4; | |
81 | packet->ip.tot_len = htobe16(len); | |
82 | ||
85923f79 TG |
83 | packet->ip.tos = IPTOS_CLASS_CS6; |
84 | ||
cf597f65 | 85 | packet->ip.protocol = IPPROTO_UDP; |
63edaa62 TG |
86 | packet->ip.saddr = source_addr; |
87 | packet->ip.daddr = destination_addr; | |
cf597f65 | 88 | |
63edaa62 TG |
89 | packet->udp.source = htobe16(source_port); |
90 | packet->udp.dest = htobe16(destination_port); | |
cf597f65 TG |
91 | |
92 | packet->udp.len = htobe16(len - DHCP_IP_SIZE); | |
93 | ||
94 | packet->ip.check = packet->udp.len; | |
0bbc2c1f | 95 | packet->udp.check = dhcp_packet_checksum((uint8_t*)&packet->ip.ttl, len - 8); |
cf597f65 TG |
96 | |
97 | packet->ip.ttl = IPDEFTTL; | |
98 | packet->ip.check = 0; | |
0bbc2c1f | 99 | packet->ip.check = dhcp_packet_checksum((uint8_t*)&packet->ip, DHCP_IP_SIZE); |
cf597f65 TG |
100 | } |
101 | ||
9faed222 | 102 | int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum, uint16_t port) { |
cf597f65 TG |
103 | size_t hdrlen; |
104 | ||
5266a81e TG |
105 | assert(packet); |
106 | ||
06b44be7 | 107 | /* IP */ |
cf597f65 | 108 | |
baaa35ad ZJS |
109 | if (packet->ip.version != IPVERSION) |
110 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
111 | "ignoring packet: not IPv4"); | |
6e34949d | 112 | |
baaa35ad ZJS |
113 | if (packet->ip.ihl < 5) |
114 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
115 | "ignoring packet: IPv4 IHL (%u words) invalid", | |
116 | packet->ip.ihl); | |
cf597f65 TG |
117 | |
118 | hdrlen = packet->ip.ihl * 4; | |
baaa35ad ZJS |
119 | if (hdrlen < 20) |
120 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
121 | "ignoring packet: IPv4 IHL (%zu bytes) " | |
122 | "smaller than minimum (20 bytes)", | |
123 | hdrlen); | |
124 | ||
125 | if (len < hdrlen) | |
126 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
127 | "ignoring packet: packet (%zu bytes) " | |
128 | "smaller than expected (%zu) by IP header", | |
129 | len, hdrlen); | |
cf597f65 | 130 | |
06b44be7 TG |
131 | /* UDP */ |
132 | ||
baaa35ad ZJS |
133 | if (packet->ip.protocol != IPPROTO_UDP) |
134 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
135 | "ignoring packet: not UDP"); | |
d454a674 | 136 | |
baaa35ad ZJS |
137 | if (len < hdrlen + be16toh(packet->udp.len)) |
138 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
139 | "ignoring packet: packet (%zu bytes) " | |
140 | "smaller than expected (%zu) by UDP header", | |
141 | len, hdrlen + be16toh(packet->udp.len)); | |
cf597f65 | 142 | |
baaa35ad ZJS |
143 | if (be16toh(packet->udp.dest) != port) |
144 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
145 | "ignoring packet: to port %u, which " | |
146 | "is not the DHCP client port (%u)", | |
147 | be16toh(packet->udp.dest), port); | |
2ad7561f TG |
148 | |
149 | /* checksums - computing these is relatively expensive, so only do it | |
150 | if all the other checks have passed | |
151 | */ | |
152 | ||
baaa35ad ZJS |
153 | if (dhcp_packet_checksum((uint8_t*)&packet->ip, hdrlen)) |
154 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
155 | "ignoring packet: invalid IP checksum"); | |
2ad7561f | 156 | |
55dab2ed | 157 | if (checksum && packet->udp.check) { |
cf597f65 TG |
158 | packet->ip.check = packet->udp.len; |
159 | packet->ip.ttl = 0; | |
160 | ||
0bbc2c1f | 161 | if (dhcp_packet_checksum((uint8_t*)&packet->ip.ttl, |
baaa35ad ZJS |
162 | be16toh(packet->udp.len) + 12)) |
163 | return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), | |
164 | "ignoring packet: invalid UDP checksum"); | |
cf597f65 TG |
165 | } |
166 | ||
cf597f65 TG |
167 | return 0; |
168 | } |