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     assert((ip_addr & htonl(~(0xf << 28))) != 0);
  42
  43     if (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 = 0x%x", ip_addr);
  73
  74     /* Check 0.0.0.0/8 invalid source-only addresses */
  75     assert((ip_addr & htonl(~(0xf << 28))) != 0);
  76
  77     /* If broadcast address */
  78     if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) {
  79         /* return Ethernet broadcast address */
  80         memset(out_ethaddr, 0xff, ETH_ALEN);
  81         return 1;
  82     }
  83
  84     for (i = 0; i < ARP_TABLE_SIZE; i++) {
  85         if (arptbl->table[i].ar_sip == ip_addr) {
  86             memcpy(out_ethaddr, arptbl->table[i].ar_sha,  ETH_ALEN);
  87             DEBUG_ARGS((dfd, " found hw addr = %02x:%02x:%02x:%02x:%02x:%02x\n",
  88                         out_ethaddr[0], out_ethaddr[1], out_ethaddr[2],
  89                         out_ethaddr[3], out_ethaddr[4], out_ethaddr[5]));
  90             return 1;
  91         }
  92     }
  93
  94     return 0;
  95 }