+++ /dev/null
-/***
- This file is part of systemd.
-
- Copyright (C) 2013 Intel Corporation. All rights reserved.
- Copyright (C) 2014 Tom Gundersen
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
-
- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
-
-#include <errno.h>
-#include <string.h>
-#include <net/ethernet.h>
-#include <net/if_arp.h>
-
-
-#include "dhcp-protocol.h"
-#include "dhcp-internal.h"
-
-#define DHCP_CLIENT_MIN_OPTIONS_SIZE 312
-
-int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid,
- uint8_t type, uint16_t arp_type, size_t optlen,
- size_t *optoffset) {
- size_t offset = 0;
- int r;
-
- assert(op == BOOTREQUEST || op == BOOTREPLY);
- assert(arp_type == ARPHRD_ETHER || arp_type == ARPHRD_INFINIBAND);
-
- message->op = op;
- message->htype = arp_type;
- message->hlen = (arp_type == ARPHRD_ETHER) ? ETHER_ADDR_LEN : 0;
- message->xid = htobe32(xid);
- message->magic = htobe32(DHCP_MAGIC_COOKIE);
-
- r = dhcp_option_append(message, optlen, &offset, 0,
- DHCP_OPTION_MESSAGE_TYPE, 1, &type);
- if (r < 0)
- return r;
-
- *optoffset = offset;
-
- return 0;
-}
-
-uint16_t dhcp_packet_checksum(uint8_t *buf, size_t len) {
- uint64_t *buf_64 = (uint64_t*)buf;
- uint64_t *end_64 = buf_64 + (len / sizeof(uint64_t));
- uint64_t sum = 0;
-
- /* See RFC1071 */
-
- while (buf_64 < end_64) {
- sum += *buf_64;
- if (sum < *buf_64)
- /* wrap around in one's complement */
- sum++;
-
- buf_64 ++;
- }
-
- if (len % sizeof(uint64_t)) {
- /* If the buffer is not aligned to 64-bit, we need
- to zero-pad the last few bytes and add them in */
- uint64_t buf_tail = 0;
-
- memcpy(&buf_tail, buf_64, len % sizeof(uint64_t));
-
- sum += buf_tail;
- if (sum < buf_tail)
- /* wrap around */
- sum++;
- }
-
- while (sum >> 16)
- sum = (sum & 0xffff) + (sum >> 16);
-
- return ~sum;
-}
-
-void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr,
- uint16_t source_port, be32_t destination_addr,
- uint16_t destination_port, uint16_t len) {
- packet->ip.version = IPVERSION;
- packet->ip.ihl = DHCP_IP_SIZE / 4;
- packet->ip.tot_len = htobe16(len);
-
- packet->ip.tos = IPTOS_CLASS_CS6;
-
- packet->ip.protocol = IPPROTO_UDP;
- packet->ip.saddr = source_addr;
- packet->ip.daddr = destination_addr;
-
- packet->udp.source = htobe16(source_port);
- packet->udp.dest = htobe16(destination_port);
-
- packet->udp.len = htobe16(len - DHCP_IP_SIZE);
-
- packet->ip.check = packet->udp.len;
- packet->udp.check = dhcp_packet_checksum((uint8_t*)&packet->ip.ttl, len - 8);
-
- packet->ip.ttl = IPDEFTTL;
- packet->ip.check = 0;
- packet->ip.check = dhcp_packet_checksum((uint8_t*)&packet->ip, DHCP_IP_SIZE);
-}
-
-int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum) {
- size_t hdrlen;
-
- assert(packet);
-
- /* IP */
-
- if (packet->ip.version != IPVERSION) {
- log_debug("ignoring packet: not IPv4");
- return -EINVAL;
- }
-
- if (packet->ip.ihl < 5) {
- log_debug("ignoring packet: IPv4 IHL (%u words) invalid",
- packet->ip.ihl);
- return -EINVAL;
- }
-
- hdrlen = packet->ip.ihl * 4;
- if (hdrlen < 20) {
- log_debug("ignoring packet: IPv4 IHL (%zu bytes) "
- "smaller than minimum (20 bytes)", hdrlen);
- return -EINVAL;
- }
-
- if (len < hdrlen) {
- log_debug("ignoring packet: packet (%zu bytes) "
- "smaller than expected (%zu) by IP header", len,
- hdrlen);
- return -EINVAL;
- }
-
- /* UDP */
-
- if (packet->ip.protocol != IPPROTO_UDP) {
- log_debug("ignoring packet: not UDP");
- return -EINVAL;
- }
-
- if (len < hdrlen + be16toh(packet->udp.len)) {
- log_debug("ignoring packet: packet (%zu bytes) "
- "smaller than expected (%zu) by UDP header", len,
- hdrlen + be16toh(packet->udp.len));
- return -EINVAL;
- }
-
- if (be16toh(packet->udp.dest) != DHCP_PORT_CLIENT) {
- log_debug("ignoring packet: to port %u, which "
- "is not the DHCP client port (%u)",
- be16toh(packet->udp.dest), DHCP_PORT_CLIENT);
- return -EINVAL;
- }
-
- /* checksums - computing these is relatively expensive, so only do it
- if all the other checks have passed
- */
-
- if (dhcp_packet_checksum((uint8_t*)&packet->ip, hdrlen)) {
- log_debug("ignoring packet: invalid IP checksum");
- return -EINVAL;
- }
-
- if (checksum && packet->udp.check) {
- packet->ip.check = packet->udp.len;
- packet->ip.ttl = 0;
-
- if (dhcp_packet_checksum((uint8_t*)&packet->ip.ttl,
- be16toh(packet->udp.len) + 12)) {
- log_debug("ignoring packet: invalid UDP checksum");
- return -EINVAL;
- }
- }
-
- return 0;
-}
~ianmdlvl / elogind.git / blobdiff