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 void arp_table_add(Slirp *slirp, uint32_t ip_addr, uint8_t ethaddr[ETH_ALEN])
  28 {
  29     const uint32_t broadcast_addr =
  30         ~slirp->vnetwork_mask.s_addr | slirp->vnetwork_addr.s_addr;
  31     ArpTable *arptbl = &slirp->arp_table;
  32     int i;
  33
  34     DEBUG_CALL("arp_table_add");
  35     DEBUG_ARG("ip = 0x%x", ip_addr);
  36     DEBUG_ARGS((dfd, " hw addr = %02x:%02x:%02x:%02x:%02x:%02x\n",
  37                 ethaddr[0], ethaddr[1], ethaddr[2],
  38                 ethaddr[3], ethaddr[4], ethaddr[5]));
  39
  40     /* Check 0.0.0.0/8 invalid source-only addresses */
  41     if ((ip_addr & htonl(~(0xfU << 28))) == 0) {
  42         return;
  43     }
  44
  45     if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) {
  46         /* Do not register broadcast addresses */
  47         return;
  48     }
  49
  50     /* Search for an entry */
  51     for (i = 0; i < ARP_TABLE_SIZE; i++) {
  52         if (arptbl->table[i].ar_sip == ip_addr) {
  53             /* Update the entry */
  54             memcpy(arptbl->table[i].ar_sha, ethaddr, ETH_ALEN);
  55             return;
  56         }
  57     }
  58
  59     /* No entry found, create a new one */
  60     arptbl->table[arptbl->next_victim].ar_sip = ip_addr;
  61     memcpy(arptbl->table[arptbl->next_victim].ar_sha,  ethaddr, ETH_ALEN);
  62     arptbl->next_victim = (arptbl->next_victim + 1) % ARP_TABLE_SIZE;
  63 }
  64
  65 bool arp_table_search(Slirp *slirp, uint32_t ip_addr,
  66                       uint8_t out_ethaddr[ETH_ALEN])
  67 {
  68     const uint32_t broadcast_addr =
  69         ~slirp->vnetwork_mask.s_addr | slirp->vnetwork_addr.s_addr;
  70     ArpTable *arptbl = &slirp->arp_table;
  71     int i;
  72
  73     DEBUG_CALL("arp_table_search");
  74     DEBUG_ARG("ip = 0x%x", ip_addr);
  75
  76     /* Check 0.0.0.0/8 invalid source-only addresses */
  77     assert((ip_addr & htonl(~(0xfU << 28))) != 0);
  78
  79     /* If broadcast address */
  80     if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) {
  81         /* return Ethernet broadcast address */
  82         memset(out_ethaddr, 0xff, ETH_ALEN);
  83         return 1;
  84     }
  85
  86     for (i = 0; i < ARP_TABLE_SIZE; i++) {
  87         if (arptbl->table[i].ar_sip == ip_addr) {
  88             memcpy(out_ethaddr, arptbl->table[i].ar_sha,  ETH_ALEN);
  89             DEBUG_ARGS((dfd, " found hw addr = %02x:%02x:%02x:%02x:%02x:%02x\n",
  90                         out_ethaddr[0], out_ethaddr[1], out_ethaddr[2],
  91                         out_ethaddr[3], out_ethaddr[4], out_ethaddr[5]));
  92             return 1;
  93         }
  94     }
  95
  96     return 0;
  97 }