slirp/src/arp_table.c

   1 /* SPDX-License-Identifier: MIT */
   2 /*
   3  * ARP table
   4  *
   5  * Copyright (c) 2011 AdaCore
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  */
  25
  26 #include "slirp.h"
  27
  28 #include <string.h>
  29
  30 void arp_table_add(Slirp *slirp, uint32_t ip_addr, uint8_t ethaddr[ETH_ALEN])
  31 {
  32     const uint32_t broadcast_addr =
  33         ~slirp->vnetwork_mask.s_addr | slirp->vnetwork_addr.s_addr;
  34     ArpTable *arptbl = &slirp->arp_table;
  35     int i;
  36
  37     DEBUG_CALL("arp_table_add");
  38     DEBUG_ARG("ip = %s", inet_ntoa((struct in_addr){.s_addr = ip_addr}));
  39     DEBUG_ARG("hw addr = %02x:%02x:%02x:%02x:%02x:%02x",
  40               ethaddr[0], ethaddr[1], ethaddr[2],
  41               ethaddr[3], ethaddr[4], ethaddr[5]);
  42
  43     if (ip_addr == 0 || ip_addr == 0xffffffff || ip_addr == broadcast_addr) {
  44         /* Do not register broadcast addresses */
  45         return;
  46     }
  47
  48     /* Search for an entry */
  49     for (i = 0; i < ARP_TABLE_SIZE; i++) {
  50         if (arptbl->table[i].ar_sip == ip_addr) {
  51             /* Update the entry */
  52             memcpy(arptbl->table[i].ar_sha, ethaddr, ETH_ALEN);
  53             return;
  54         }
  55     }
  56
  57     /* No entry found, create a new one */
  58     arptbl->table[arptbl->next_victim].ar_sip = ip_addr;
  59     memcpy(arptbl->table[arptbl->next_victim].ar_sha,  ethaddr, ETH_ALEN);
  60     arptbl->next_victim = (arptbl->next_victim + 1) % ARP_TABLE_SIZE;
  61 }
  62
  63 bool arp_table_search(Slirp *slirp, uint32_t ip_addr,
  64                       uint8_t out_ethaddr[ETH_ALEN])
  65 {
  66     const uint32_t broadcast_addr =
  67         ~slirp->vnetwork_mask.s_addr | slirp->vnetwork_addr.s_addr;
  68     ArpTable *arptbl = &slirp->arp_table;
  69     int i;
  70
  71     DEBUG_CALL("arp_table_search");
  72     DEBUG_ARG("ip = %s", inet_ntoa((struct in_addr){.s_addr = ip_addr}));
  73
  74     /* If broadcast address */
  75     if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) {
  76         /* return Ethernet broadcast address */
  77         memset(out_ethaddr, 0xff, ETH_ALEN);
  78         return 1;
  79     }
  80
  81     for (i = 0; i < ARP_TABLE_SIZE; i++) {
  82         if (arptbl->table[i].ar_sip == ip_addr) {
  83             memcpy(out_ethaddr, arptbl->table[i].ar_sha,  ETH_ALEN);
  84             DEBUG_ARG("found hw addr = %02x:%02x:%02x:%02x:%02x:%02x",
  85                       out_ethaddr[0], out_ethaddr[1], out_ethaddr[2],
  86                       out_ethaddr[3], out_ethaddr[4], out_ethaddr[5]);
  87             return 1;
  88         }
  89     }
  90
  91     return 0;
  92 }