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/*
* virarptable.c Linux ARP table handling
*
* Copyright (C) 2018 Chen Hanxiao
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#ifdef __linux__
# include <linux/rtnetlink.h>
#endif
#include "viralloc.h"
#include "virarptable.h"
#include "virerror.h"
#include "virlog.h"
#include "virnetlink.h"
#include "virsocketaddr.h"
#define VIR_FROM_THIS VIR_FROM_NONE
VIR_LOG_INIT("util.arptable");
#ifdef __linux__
# define NDA_RTA(r) \
((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ndmsg))))
static int
parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int len)
{
memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
VIR_WARNINGS_NO_CAST_ALIGN
for (; RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
VIR_WARNINGS_RESET
if ((rta->rta_type <= max) && (!tb[rta->rta_type]))
tb[rta->rta_type] = rta;
}
if (len)
VIR_WARN("malformed netlink message: Deficit %d, rta_len=%d",
len, rta->rta_len);
return 0;
}
virArpTable *
virArpTableGet(void)
{
int num = 0;
int msglen;
g_autofree void *nlData = NULL;
virArpTable *table = NULL;
struct nlmsghdr* nh;
struct rtattr * tb[NDA_MAX+1];
msglen = virNetlinkGetNeighbor(&nlData, 0, 0);
if (msglen < 0)
return NULL;
table = g_new0(virArpTable, 1);
nh = (struct nlmsghdr*)nlData;
VIR_WARNINGS_NO_CAST_ALIGN
for (; NLMSG_OK(nh, msglen); nh = NLMSG_NEXT(nh, msglen)) {
VIR_WARNINGS_RESET
struct ndmsg *r = NLMSG_DATA(nh);
int len = nh->nlmsg_len;
void *addr;
if ((len -= NLMSG_LENGTH(sizeof(*nh))) < 0) {
virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("wrong nlmsg len"));
goto cleanup;
}
if (r->ndm_family && (r->ndm_family != AF_INET))
continue;
/* catch stale and reachalbe arp entry only */
if (r->ndm_state &&
(!(r->ndm_state == NUD_STALE || r->ndm_state == NUD_REACHABLE)))
continue;
if (nh->nlmsg_type == NLMSG_DONE)
return table;
VIR_WARNINGS_NO_CAST_ALIGN
parse_rtattr(tb, NDA_MAX, NDA_RTA(r),
nh->nlmsg_len - NLMSG_LENGTH(sizeof(*r)));
VIR_WARNINGS_RESET
if (tb[NDA_DST] == NULL || tb[NDA_LLADDR] == NULL)
continue;
if (tb[NDA_DST]) {
g_autofree char *ipstr = NULL;
virSocketAddr virAddr;
VIR_REALLOC_N(table->t, num + 1);
table->n = num + 1;
addr = RTA_DATA(tb[NDA_DST]);
memset(&virAddr, 0, sizeof(virAddr));
virAddr.len = sizeof(virAddr.data.inet4);
virAddr.data.inet4.sin_family = AF_INET;
virAddr.data.inet4.sin_addr = *(struct in_addr *)addr;
ipstr = virSocketAddrFormat(&virAddr);
table->t[num].ipaddr = g_strdup(ipstr);
}
if (tb[NDA_LLADDR]) {
virMacAddr macaddr;
char ifmac[VIR_MAC_STRING_BUFLEN];
addr = RTA_DATA(tb[NDA_LLADDR]);
memcpy(macaddr.addr, addr, VIR_MAC_BUFLEN);
virMacAddrFormat(&macaddr, ifmac);
table->t[num].mac = g_strdup(ifmac);
num++;
}
}
return table;
cleanup:
virArpTableFree(table);
return NULL;
}
#else
virArpTable *
virArpTableGet(void)
{
virReportError(VIR_ERR_NO_SUPPORT, "%s",
_("get arp table not implemented on this platform"));
return NULL;
}
#endif /* __linux__ */
void
virArpTableFree(virArpTable *table)
{
size_t i;
if (!table)
return;
for (i = 0; i < table->n; i++) {
g_free(table->t[i].ipaddr);
g_free(table->t[i].mac);
}
g_free(table->t);
g_free(table);
}
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