src/libsystemd-network/ipv4ll-packet.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright (C) 2014 Axis Communications AB. All rights reserved.
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19 #include <arpa/inet.h>
  20
  21 #include "util.h"
  22 #include "ipv4ll-internal.h"
  23
  24 void arp_packet_init(struct ether_arp *arp) {
  25         assert(arp);
  26
  27         memzero(arp, sizeof(struct ether_arp));
  28         /* Header */
  29         arp->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); /* HTYPE */
  30         arp->ea_hdr.ar_pro = htons(ETHERTYPE_IP); /* PTYPE */
  31         arp->ea_hdr.ar_hln = ETH_ALEN; /* HLEN */
  32         arp->ea_hdr.ar_pln = sizeof arp->arp_spa; /* PLEN */
  33         arp->ea_hdr.ar_op = htons(ARPOP_REQUEST); /* REQUEST */
  34 }
  35
  36 void arp_packet_probe(struct ether_arp *arp, be32_t pa, const struct ether_addr *ha) {
  37         assert(ha);
  38
  39         arp_packet_init(arp);
  40         memcpy(arp->arp_sha, ha, ETH_ALEN);
  41         memcpy(arp->arp_tpa, &pa, sizeof(pa));
  42 }
  43
  44 void arp_packet_announcement(struct ether_arp *arp, be32_t pa, const struct ether_addr *ha) {
  45         assert(ha);
  46
  47         arp_packet_init(arp);
  48         memcpy(arp->arp_sha, ha, ETH_ALEN);
  49         memcpy(arp->arp_tpa, &pa, sizeof(pa));
  50         memcpy(arp->arp_spa, &pa, sizeof(pa));
  51 }
  52
  53 int arp_packet_verify_headers(struct ether_arp *arp) {
  54         assert(arp);
  55
  56         if (arp->ea_hdr.ar_hrd != htons(ARPHRD_ETHER)) {
  57                 log_ipv4ll(NULL, "ignoring packet: header is not ARPHRD_ETHER");
  58                 return -EINVAL;
  59         }
  60         if (arp->ea_hdr.ar_pro != htons(ETHERTYPE_IP)) {
  61                 log_ipv4ll(NULL, "ignoring packet: protocol is not ETHERTYPE_IP");
  62                 return -EINVAL;
  63         }
  64         if (arp->ea_hdr.ar_op != htons(ARPOP_REQUEST) &&
  65             arp->ea_hdr.ar_op != htons(ARPOP_REPLY)) {
  66                 log_ipv4ll(NULL, "ignoring packet: operation is not ARPOP_REQUEST or ARPOP_REPLY");
  67                 return -EINVAL;
  68         }
  69
  70         return 0;
  71 }