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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
//
// Add routes on Linux using AF_NETLINK socket
#ifndef OPENVPN_NETCONF_LINUX_ROUTE_H
#define OPENVPN_NETCONF_LINUX_ROUTE_H
#include <cstring>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <net/if.h>
#include <errno.h>
#include <string>
#include <openvpn/common/exception.hpp>
#include <openvpn/common/scoped_fd.hpp>
#include <openvpn/common/strerror.hpp>
#include <openvpn/addr/route.hpp>
namespace openvpn {
class LinuxRoute
{
public:
OPENVPN_EXCEPTION(linux_route_error);
LinuxRoute()
{
fd.reset(::socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE));
if (!fd.defined())
throw linux_route_error("creating AF_NETLINK socket");
struct sockaddr_nl local;
::memset(&local, 0, sizeof(local));
local.nl_family = AF_NETLINK;
local.nl_pad = 0;
local.nl_pid = 0; // only use getpid() if unique instantiation per process
local.nl_groups = 0;
if (::bind(fd(), (struct sockaddr *)&local, sizeof(local)) < 0)
throw linux_route_error("binding to AF_NETLINK socket");
}
void add_delete(const bool add,
const IP::Route &route,
const int if_index,
const int table = RT_TABLE_MAIN)
{
typedef struct
{
struct nlmsghdr nlmsg_info;
struct rtmsg rtmsg_info;
char buffer[64]; // must be large enough to contain request
} netlink_req_t;
struct rtattr *rtattr_ptr;
int rtmsg_len;
struct sockaddr_nl peer;
struct msghdr msg_info;
struct iovec iov_info;
netlink_req_t netlink_req;
::memset(&peer, 0, sizeof(peer));
peer.nl_family = AF_NETLINK;
peer.nl_pad = 0;
peer.nl_pid = 0;
peer.nl_groups = 0;
::memset(&msg_info, 0, sizeof(msg_info));
msg_info.msg_name = (void *)&peer;
msg_info.msg_namelen = sizeof(peer);
::memset(&netlink_req, 0, sizeof(netlink_req));
rtmsg_len = sizeof(struct rtmsg);
// add destination addr
rtattr_ptr = (struct rtattr *)netlink_req.buffer;
rtattr_ptr->rta_type = RTA_DST;
rtattr_ptr->rta_len = sizeof(struct rtattr) + route.addr.size_bytes();
route.addr.to_byte_string_variable(((unsigned char *)rtattr_ptr) + sizeof(struct rtattr));
rtmsg_len += rtattr_ptr->rta_len;
// add if_index
rtattr_ptr = (struct rtattr *)(((unsigned char *)rtattr_ptr) + rtattr_ptr->rta_len);
rtattr_ptr->rta_type = RTA_OIF;
rtattr_ptr->rta_len = sizeof(struct rtattr) + 4;
::memcpy(((unsigned char *)rtattr_ptr) + sizeof(struct rtattr), &if_index, 4);
rtmsg_len += rtattr_ptr->rta_len;
netlink_req.nlmsg_info.nlmsg_len = NLMSG_LENGTH(rtmsg_len);
if (add)
{
netlink_req.nlmsg_info.nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE;
netlink_req.nlmsg_info.nlmsg_type = RTM_NEWROUTE;
}
else // delete
{
netlink_req.nlmsg_info.nlmsg_flags = NLM_F_REQUEST;
netlink_req.nlmsg_info.nlmsg_type = RTM_DELROUTE;
}
netlink_req.rtmsg_info.rtm_family = route.addr.family();
netlink_req.rtmsg_info.rtm_table = table;
netlink_req.rtmsg_info.rtm_dst_len = route.prefix_len; // add prefix
netlink_req.rtmsg_info.rtm_protocol = RTPROT_STATIC;
netlink_req.rtmsg_info.rtm_scope = RT_SCOPE_UNIVERSE;
netlink_req.rtmsg_info.rtm_type = RTN_UNICAST;
iov_info.iov_base = (void *)&netlink_req.nlmsg_info;
iov_info.iov_len = netlink_req.nlmsg_info.nlmsg_len;
msg_info.msg_iov = &iov_info;
msg_info.msg_iovlen = 1;
const ssize_t status = ::sendmsg(fd(), &msg_info, 0);
if (status < 0)
{
const int eno = errno;
OPENVPN_THROW(linux_route_error, "add_delete: sendmsg failed: " << strerror_str(eno));
}
}
static int if_index(const std::string &iface)
{
const unsigned int ret = ::if_nametoindex(iface.c_str());
if (!ret)
OPENVPN_THROW(linux_route_error, "if_index: no such interface: " << iface);
return ret;
}
private:
ScopedFD fd;
};
} // namespace openvpn
#endif
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