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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012- OpenVPN Inc.
//
// SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
// Find default gateways on Linux using ip route command
#pragma once
#include <string>
#include <openvpn/common/exception.hpp>
#include <openvpn/addr/ip.hpp>
#include <openvpn/addr/ipv4.hpp>
#include <openvpn/addr/ipv6.hpp>
#include <openvpn/tun/linux/client/sitnl.hpp>
namespace openvpn {
class LinuxGWNetlink
{
public:
OPENVPN_EXCEPTION(linux_gw_netlink_error);
/**
* Provides gateway which is used to reach given address
*
* @param addr address which we want to reach
* @param iface_to_ignore this allows to exclude certain interface
* from discovered gateways. Used when we want to exclude VPN interface
* when there is active VPN connection with redirected default gateway
*
* @param ipv6 true if address is IPv6
*/
LinuxGWNetlink(const std::string &addr, const std::string &iface_to_ignore, bool ipv6)
{
try
{
if (ipv6)
{
IPv6::Addr addr6;
if (TunNetlink::SITNL::net_route_best_gw(IP::Route6::from_string(addr),
addr6,
dev_,
iface_to_ignore)
< 0)
{
OPENVPN_THROW(linux_gw_netlink_error,
"error retrieving default IPv6 GW");
}
addr_ = IP::Addr::from_ipv6(addr6);
}
else
{
IPv4::Addr addr4;
if (TunNetlink::SITNL::net_route_best_gw(IP::Route4::from_string(addr),
addr4,
dev_,
iface_to_ignore)
< 0)
{
OPENVPN_THROW(linux_gw_netlink_error,
"error retrieving default IPv4 GW");
}
addr_ = IP::Addr::from_ipv4(addr4);
}
}
catch (...)
{
/* nothing to do. just leave default GW unassigned */
}
}
const std::string &dev() const
{
return dev_;
}
const IP::Addr &addr() const
{
return addr_;
}
bool defined() const
{
return !dev_.empty() && addr_.defined();
}
std::string to_string() const
{
return dev_ + '/' + addr_.to_string();
}
private:
IP::Addr addr_;
std::string dev_;
};
/**
* Provides IPv4/6 gateway which is used to reach given address
*
* @param iface_to_ignore this allows to exclude certain interface
* from discovered gateways. Used when we want to exclude VPN interface
* when there is active VPN connection with redirected default gateway
* @param addr address which we want to reach
*/
struct LinuxGW46Netlink
{
LinuxGW46Netlink(const std::string &iface_to_ignore, const std::string &addr = "")
: v4(addr.empty() ? IPv4::Addr::from_zero().to_string() : addr, iface_to_ignore, false),
v6(addr.empty() ? IPv6::Addr::from_zero().to_string() : addr, iface_to_ignore, true)
{
}
std::string to_string() const
{
std::string ret = "[";
if (v4.defined())
{
ret += "4:";
ret += v4.to_string();
}
if (v6.defined())
{
if (v4.defined())
ret += ' ';
ret += "6:";
ret += v6.to_string();
}
ret += "]";
return ret;
}
std::string dev() const
{
if (v4.defined())
return v4.dev();
else if (v6.defined())
return v6.dev();
else
throw LinuxGWNetlink::linux_gw_netlink_error("cannot determine gateway interface");
}
LinuxGWNetlink v4;
LinuxGWNetlink v6;
};
} // namespace openvpn
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