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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
//
// Emulate Excluded Routes implementation (needed by Android)
#ifndef OPENVPN_CLIENT_CLIEMUEXR_H
#define OPENVPN_CLIENT_CLIEMUEXR_H
#include <openvpn/common/exception.hpp>
#include <openvpn/tun/client/emuexr.hpp>
#include <openvpn/addr/addrspacesplit.hpp>
namespace openvpn {
class EmulateExcludeRouteImpl : public EmulateExcludeRoute
{
public:
OPENVPN_EXCEPTION(emulate_exclude_route_error);
typedef RCPtr<EmulateExcludeRouteImpl> Ptr;
explicit EmulateExcludeRouteImpl(const bool exclude_server_address)
: exclude_server_address_(exclude_server_address)
{
}
private:
void add_route(const bool add, const IP::Addr &addr, const int prefix_len) override
{
(add ? include : exclude).emplace_back(addr, prefix_len);
}
void add_default_routes(bool ipv4, bool ipv6) override
{
if (ipv4)
add_route(true, IP::Addr::from_zero(IP::Addr::V4), 0);
if (ipv6)
add_route(true, IP::Addr::from_zero(IP::Addr::V6), 0);
}
bool enabled(const IPVerFlags &ipv) const override
{
return exclude.size() && (ipv.rgv4() || ipv.rgv6());
}
void emulate(TunBuilderBase *tb, IPVerFlags &ipv, const IP::Addr &server_addr) const override
{
const unsigned int ip_ver_flags = ipv.ip_ver_flags();
IP::RouteList rl, tempExcludeList;
rl.reserve(include.size() + exclude.size());
rl.insert(rl.end(), include.begin(), include.end());
rl.insert(rl.end(), exclude.begin(), exclude.end());
// Check if we have to exclude the server, if yes we temporarily add it to the list
// of excluded networks as small individual /32 or /128 network
const IP::RouteList *excludedRoutes = &exclude;
if (exclude_server_address_
&& (server_addr.version_mask() & ip_ver_flags)
&& !exclude.contains(IP::Route(server_addr, server_addr.size())))
{
rl.emplace_back(server_addr, server_addr.size());
// Create a temporary list that includes all the routes + the server
tempExcludeList = exclude;
tempExcludeList.emplace_back(server_addr, server_addr.size());
excludedRoutes = &tempExcludeList;
}
if (excludedRoutes->empty())
{
// Samsung's Android VPN API does different things if you have
// 0.0.0.0/0 in the list of installed routes
// (even if 0.0.0.0/1 and 128.0.0.0/1 and are present it behaves different)
// We normally always split the address space, breaking a 0.0.0.0/0 into
// smaller routes. If no routes are excluded, we install the original
// routes without modifying them
for (const auto &rt : include)
{
if (rt.version() & ip_ver_flags)
{
if (!tb->tun_builder_add_route(rt.addr.to_string(), rt.prefix_len, -1, rt.addr.version() == IP::Addr::V6))
throw emulate_exclude_route_error("tun_builder_add_route failed");
}
}
return;
}
// Complete address space (0.0.0.0/0 or ::/0) split into smaller networks
// Figure out which parts of this non overlapping address we want to install
for (const auto &r : IP::AddressSpaceSplitter(rl, ip_ver_flags))
{
if (check_route_should_be_installed(r, *excludedRoutes))
if (!tb->tun_builder_add_route(r.addr.to_string(), r.prefix_len, -1, r.addr.version() == IP::Addr::V6))
throw emulate_exclude_route_error("tun_builder_add_route failed");
}
ipv.set_emulate_exclude_routes();
}
bool check_route_should_be_installed(const IP::Route &r, const IP::RouteList &excludedRoutes) const
{
// The whole address space was partioned into NON-overlapping routes that
// we get one by one with the parameter r.
// Therefore we already know that the whole route r either is included or
// excluded IPs.
// Figure out if this particular route should be installed or not
IP::Route const *bestroute = nullptr;
// Get the best (longest-prefix/smallest) route from included routes that completely
// matches this route
for (const auto &incRoute : include)
{
if (incRoute.contains(r))
{
if (!bestroute || bestroute->prefix_len < incRoute.prefix_len)
bestroute = &incRoute;
}
}
// No positive route matches the route at all, do not install it
if (!bestroute)
return false;
// Check if there is a more specific exclude route
for (const auto &exclRoute : excludedRoutes)
{
if (exclRoute.contains(r) && exclRoute.prefix_len > bestroute->prefix_len)
return false;
}
return true;
}
const bool exclude_server_address_;
IP::RouteList include;
IP::RouteList exclude;
};
class EmulateExcludeRouteFactoryImpl : public EmulateExcludeRouteFactory
{
public:
typedef RCPtr<EmulateExcludeRouteFactoryImpl> Ptr;
EmulateExcludeRouteFactoryImpl(const bool exclude_server_address)
: exclude_server_address_(exclude_server_address)
{
}
private:
EmulateExcludeRoute::Ptr new_obj() const override
{
return EmulateExcludeRoute::Ptr(new EmulateExcludeRouteImpl(exclude_server_address_));
}
const bool exclude_server_address_;
};
} // namespace openvpn
#endif
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