src/ndp_table.c

/* SPDX-License-Identifier: BSD-3-Clause */
/*
 * Copyright (c) 2013
 * Guillaume Subiron, Yann Bordenave, Serigne Modou Wagne.
 */

#include "slirp.h"

void ndp_table_add(Slirp *slirp, struct in6_addr ip_addr,
                   uint8_t ethaddr[ETH_ALEN])
{
    char addrstr[INET6_ADDRSTRLEN];
    NdpTable *ndp_table = &slirp->ndp_table;
    int i;
    char ethaddr_str[ETH_ADDRSTRLEN];

    inet_ntop(AF_INET6, &(ip_addr), addrstr, INET6_ADDRSTRLEN);

    DEBUG_CALL("ndp_table_add");
    DEBUG_ARG("ip = %s", addrstr);
    DEBUG_ARG("hw addr = %s", slirp_ether_ntoa(ethaddr, ethaddr_str,
                                               sizeof(ethaddr_str)));

    if (IN6_IS_ADDR_MULTICAST(&ip_addr) || in6_zero(&ip_addr)
            || in6_equal(&ip_addr, &slirp->vhost_addr6)
            || in6_equal(&ip_addr, &slirp->vnameserver_addr6)) {
        /* Do not register multicast or unspecified addresses */
        DEBUG_CALL(" abort: do not register multicast or unspecified address");
        return;
    }

    /* Search for an entry */
    for (i = 0; i < NDP_TABLE_SIZE; i++) {
        if (in6_equal(&ndp_table->table[i].ip_addr, &ip_addr)) {
            DEBUG_CALL(" already in table: update the entry");
            /* Update the entry */
            memcpy(ndp_table->table[i].eth_addr, ethaddr, ETH_ALEN);
            return;
        }
    }

    /* No entry found, create a new one */
    DEBUG_CALL(" create new entry");
    /* Save the first entry, it is the guest. */
    if (in6_zero(&ndp_table->guest_in6_addr)) {
        ndp_table->guest_in6_addr = ip_addr;
    }
    ndp_table->table[ndp_table->next_victim].ip_addr = ip_addr;
    memcpy(ndp_table->table[ndp_table->next_victim].eth_addr, ethaddr,
           ETH_ALEN);
    ndp_table->next_victim = (ndp_table->next_victim + 1) % NDP_TABLE_SIZE;
}

bool ndp_table_search(Slirp *slirp, struct in6_addr ip_addr,
                      uint8_t out_ethaddr[ETH_ALEN])
{
    char addrstr[INET6_ADDRSTRLEN];
    NdpTable *ndp_table = &slirp->ndp_table;
    int i;
    char ethaddr_str[ETH_ADDRSTRLEN];

    inet_ntop(AF_INET6, &(ip_addr), addrstr, INET6_ADDRSTRLEN);

    DEBUG_CALL("ndp_table_search");
    DEBUG_ARG("ip = %s", addrstr);

    /* If unspecified address */
    if (in6_zero(&ip_addr)) {
        /* return Ethernet broadcast address */
        memset(out_ethaddr, 0xff, ETH_ALEN);
        return 1;
    }

    /* Multicast address: fec0::abcd:efgh/8 -> 33:33:ab:cd:ef:gh */
    if (IN6_IS_ADDR_MULTICAST(&ip_addr)) {
        out_ethaddr[0] = 0x33;
        out_ethaddr[1] = 0x33;
        out_ethaddr[2] = ip_addr.s6_addr[12];
        out_ethaddr[3] = ip_addr.s6_addr[13];
        out_ethaddr[4] = ip_addr.s6_addr[14];
        out_ethaddr[5] = ip_addr.s6_addr[15];
        DEBUG_ARG("multicast addr = %s",
                  slirp_ether_ntoa(out_ethaddr, ethaddr_str,
                                   sizeof(ethaddr_str)));
        return 1;
    }

    for (i = 0; i < NDP_TABLE_SIZE; i++) {
        if (in6_equal(&ndp_table->table[i].ip_addr, &ip_addr)) {
            memcpy(out_ethaddr, ndp_table->table[i].eth_addr, ETH_ALEN);
            DEBUG_ARG("found hw addr = %s",
                      slirp_ether_ntoa(out_ethaddr, ethaddr_str,
                                       sizeof(ethaddr_str)));
            return 1;
        }
    }

    DEBUG_CALL(" ip not found in table");
    return 0;
}