slirp/arp_table.c

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