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/* $Id: rtmon_bsd.c $ */
/** @file
* NAT Network - IPv6 default route monitor for BSD routing sockets.
*/
/*
* Copyright (C) 2013-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#define LOG_GROUP LOG_GROUP_NAT_SERVICE
#include "proxy.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
/**
* Query IPv6 routing table - BSD routing sockets version.
*
* We don't actually monitor the routing socket for updates, and
* instead query the kernel each time.
*
* We take a shortcut and don't read the reply to our RTM_GET - if
* there's no default IPv6 route, write(2) will fail with ESRCH
* synchronously. In theory it may fail asynchronously and we should
* wait for the RTM_GET reply and check rt_msghdr::rtm_errno.
*
* KAME code in *BSD maintains internally a list of default routers
* that it learned from RAs, and installs only one of them into the
* routing table (actually, I'm not sure if BSD routing table can
* handle multiple routes to the same destination). One side-effect
* of this is that when manually configured route (e.g. teredo) is
* deleted, the system will lose its default route even when KAME IPv6
* has default router(s) in its internal list. Next RA will force the
* update, though.
*
* Solaris does expose multiple routes in the routing table and
* replies to RTM_GET with "default default".
*/
int
rtmon_get_defaults(void)
{
int rtsock;
struct req {
struct rt_msghdr rtm;
struct sockaddr_in6 dst;
struct sockaddr_in6 mask;
struct sockaddr_dl ifp;
} req;
ssize_t nsent;
rtsock = socket(PF_ROUTE, SOCK_RAW, AF_INET6);
if (rtsock < 0) {
DPRINTF0(("rtmon: failed to create routing socket\n"));
return -1;
}
memset(&req, 0, sizeof(req));
req.rtm.rtm_type = RTM_GET;
req.rtm.rtm_version = RTM_VERSION;
req.rtm.rtm_msglen = sizeof(req);
req.rtm.rtm_seq = 0x12345;
req.rtm.rtm_flags = RTF_UP;
req.rtm.rtm_addrs = RTA_DST | RTA_NETMASK | RTA_IFP;
req.dst.sin6_family = AF_INET6;
#if HAVE_SA_LEN
req.dst.sin6_len = sizeof(req.dst);
#endif
req.mask.sin6_family = AF_INET6;
#if HAVE_SA_LEN
req.mask.sin6_len = sizeof(req.mask);
#endif
req.ifp.sdl_family = AF_LINK;
#if HAVE_SA_LEN
req.ifp.sdl_len = sizeof(req.ifp);
#endif
nsent = write(rtsock, &req, req.rtm.rtm_msglen);
if (nsent < 0) {
if (errno == ESRCH) {
/* there's no default route */
return 0;
}
else {
DPRINTF0(("rtmon: failed to send RTM_GET\n"));
return -1;
}
}
return 1;
}
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