2017-11-18 17:09:20 +01:00
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/* SPDX-License-Identifier: LGPL-2.1+ */
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2014-02-11 13:11:18 +01:00
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/***
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2018-06-12 17:15:23 +02:00
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Copyright © 2013 Intel Corporation. All rights reserved.
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2014-02-11 13:11:18 +01:00
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***/
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#include <errno.h>
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#include <net/ethernet.h>
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#include <net/if_arp.h>
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2015-11-16 22:09:36 +01:00
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#include <string.h>
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2014-02-11 13:11:18 +01:00
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#include "dhcp-internal.h"
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2015-11-16 22:09:36 +01:00
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#include "dhcp-protocol.h"
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2014-02-11 13:11:18 +01:00
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#define DHCP_CLIENT_MIN_OPTIONS_SIZE 312
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int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid,
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2014-10-08 21:15:45 +02:00
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uint8_t type, uint16_t arp_type, size_t optlen,
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size_t *optoffset) {
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2014-05-20 11:04:50 +02:00
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size_t offset = 0;
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int r;
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2014-02-11 13:11:18 +01:00
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2017-09-29 00:37:23 +02:00
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assert(IN_SET(op, BOOTREQUEST, BOOTREPLY));
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assert(IN_SET(arp_type, ARPHRD_ETHER, ARPHRD_INFINIBAND));
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2014-02-23 22:07:07 +01:00
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2014-02-11 13:11:18 +01:00
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message->op = op;
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2014-10-08 21:15:45 +02:00
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message->htype = arp_type;
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message->hlen = (arp_type == ARPHRD_ETHER) ? ETHER_ADDR_LEN : 0;
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2014-02-11 13:11:18 +01:00
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message->xid = htobe32(xid);
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2014-04-06 14:05:32 +02:00
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message->magic = htobe32(DHCP_MAGIC_COOKIE);
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2014-02-11 13:11:18 +01:00
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2014-05-21 15:55:02 +02:00
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r = dhcp_option_append(message, optlen, &offset, 0,
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2016-01-20 14:44:24 +01:00
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SD_DHCP_OPTION_MESSAGE_TYPE, 1, &type);
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2014-05-20 11:04:50 +02:00
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if (r < 0)
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return r;
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2014-02-11 13:11:18 +01:00
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2014-05-20 11:04:50 +02:00
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*optoffset = offset;
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2014-02-11 13:11:18 +01:00
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return 0;
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}
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2014-06-16 15:24:28 +02:00
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uint16_t dhcp_packet_checksum(uint8_t *buf, size_t len) {
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uint64_t *buf_64 = (uint64_t*)buf;
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uint64_t *end_64 = buf_64 + (len / sizeof(uint64_t));
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2014-04-02 10:00:31 +02:00
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uint64_t sum = 0;
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2014-06-16 15:24:28 +02:00
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/* See RFC1071 */
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2014-04-02 10:00:31 +02:00
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while (buf_64 < end_64) {
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sum += *buf_64;
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if (sum < *buf_64)
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2014-06-16 15:24:28 +02:00
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/* wrap around in one's complement */
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2014-04-02 10:00:31 +02:00
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sum++;
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2016-02-23 05:32:04 +01:00
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buf_64++;
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2014-04-02 10:00:31 +02:00
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}
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2014-06-16 15:24:28 +02:00
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if (len % sizeof(uint64_t)) {
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/* If the buffer is not aligned to 64-bit, we need
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to zero-pad the last few bytes and add them in */
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uint64_t buf_tail = 0;
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2014-02-11 13:11:18 +01:00
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2014-06-16 15:24:28 +02:00
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memcpy(&buf_tail, buf_64, len % sizeof(uint64_t));
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2014-02-11 13:11:18 +01:00
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2014-06-16 15:24:28 +02:00
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sum += buf_tail;
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if (sum < buf_tail)
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/* wrap around */
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2014-04-02 10:00:31 +02:00
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sum++;
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2014-02-11 13:11:18 +01:00
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}
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while (sum >> 16)
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sum = (sum & 0xffff) + (sum >> 16);
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return ~sum;
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}
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2014-03-09 22:51:07 +01:00
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void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr,
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uint16_t source_port, be32_t destination_addr,
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2019-09-23 13:25:21 +02:00
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uint16_t destination_port, uint16_t len, int ip_service_type) {
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2014-02-11 13:11:18 +01:00
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packet->ip.version = IPVERSION;
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packet->ip.ihl = DHCP_IP_SIZE / 4;
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packet->ip.tot_len = htobe16(len);
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2019-09-23 13:25:21 +02:00
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if (ip_service_type >= 0)
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packet->ip.tos = ip_service_type;
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else
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packet->ip.tos = IPTOS_CLASS_CS6;
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2014-05-06 22:02:14 +02:00
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2014-02-11 13:11:18 +01:00
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packet->ip.protocol = IPPROTO_UDP;
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2014-03-09 22:51:07 +01:00
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packet->ip.saddr = source_addr;
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packet->ip.daddr = destination_addr;
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2014-02-11 13:11:18 +01:00
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2014-03-09 22:51:07 +01:00
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packet->udp.source = htobe16(source_port);
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packet->udp.dest = htobe16(destination_port);
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2014-02-11 13:11:18 +01:00
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packet->udp.len = htobe16(len - DHCP_IP_SIZE);
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packet->ip.check = packet->udp.len;
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2014-06-16 15:24:28 +02:00
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packet->udp.check = dhcp_packet_checksum((uint8_t*)&packet->ip.ttl, len - 8);
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2014-02-11 13:11:18 +01:00
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packet->ip.ttl = IPDEFTTL;
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packet->ip.check = 0;
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2014-06-16 15:24:28 +02:00
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packet->ip.check = dhcp_packet_checksum((uint8_t*)&packet->ip, DHCP_IP_SIZE);
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2014-02-11 13:11:18 +01:00
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}
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2016-11-11 00:34:19 +01:00
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int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum, uint16_t port) {
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2014-02-11 13:11:18 +01:00
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size_t hdrlen;
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2014-02-23 17:30:13 +01:00
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assert(packet);
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2014-02-23 14:15:05 +01:00
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/* IP */
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2014-02-11 13:11:18 +01:00
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2018-11-20 23:40:44 +01:00
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if (packet->ip.version != IPVERSION)
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return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
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"ignoring packet: not IPv4");
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2014-03-30 20:33:57 +02:00
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2018-11-20 23:40:44 +01:00
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if (packet->ip.ihl < 5)
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return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
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"ignoring packet: IPv4 IHL (%u words) invalid",
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packet->ip.ihl);
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2014-02-11 13:11:18 +01:00
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hdrlen = packet->ip.ihl * 4;
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2018-11-20 23:40:44 +01:00
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if (hdrlen < 20)
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return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
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"ignoring packet: IPv4 IHL (%zu bytes) "
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"smaller than minimum (20 bytes)",
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hdrlen);
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if (len < hdrlen)
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return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
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"ignoring packet: packet (%zu bytes) "
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"smaller than expected (%zu) by IP header",
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len, hdrlen);
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2014-02-11 13:11:18 +01:00
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2014-02-23 14:15:05 +01:00
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/* UDP */
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2018-11-20 23:40:44 +01:00
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if (packet->ip.protocol != IPPROTO_UDP)
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return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
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"ignoring packet: not UDP");
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2014-03-30 19:09:14 +02:00
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2018-11-20 23:40:44 +01:00
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if (len < hdrlen + be16toh(packet->udp.len))
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return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
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"ignoring packet: packet (%zu bytes) "
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"smaller than expected (%zu) by UDP header",
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len, hdrlen + be16toh(packet->udp.len));
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2014-02-11 13:11:18 +01:00
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2018-11-20 23:40:44 +01:00
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if (be16toh(packet->udp.dest) != port)
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return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
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"ignoring packet: to port %u, which "
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"is not the DHCP client port (%u)",
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be16toh(packet->udp.dest), port);
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2014-03-30 20:36:44 +02:00
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/* checksums - computing these is relatively expensive, so only do it
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if all the other checks have passed
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*/
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2018-11-20 23:40:44 +01:00
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if (dhcp_packet_checksum((uint8_t*)&packet->ip, hdrlen))
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return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
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"ignoring packet: invalid IP checksum");
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2014-03-30 20:36:44 +02:00
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2014-02-24 01:09:21 +01:00
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if (checksum && packet->udp.check) {
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2014-02-11 13:11:18 +01:00
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packet->ip.check = packet->udp.len;
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packet->ip.ttl = 0;
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2014-06-16 15:24:28 +02:00
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if (dhcp_packet_checksum((uint8_t*)&packet->ip.ttl,
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2018-11-20 23:40:44 +01:00
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be16toh(packet->udp.len) + 12))
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return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
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"ignoring packet: invalid UDP checksum");
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2014-02-11 13:11:18 +01:00
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}
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return 0;
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}
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