networking_sitnl.c

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/*
 *  Simplified Interface To NetLink
 *
 *  Copyright (C) 2016-2023 Antonio Quartulli <a@unstable.cc>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  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 (see the file COPYING included with this
 *  distribution); if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#ifdef TARGET_LINUX
 
#include "syshead.h"
 
#include "dco.h"
#include "errlevel.h"
#include "buffer.h"
#include "misc.h"
#include "networking.h"
#include "proto.h"
 
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
 
#define SNDBUF_SIZE (1024 * 2)
#define RCVBUF_SIZE (1024 * 4)
 
#define SITNL_ADDATTR(_msg, _max_size, _attr, _data, _size)         \
    {                                                               \
        if (sitnl_addattr(_msg, _max_size, _attr, _data, _size) < 0) \
        {                                                           \
            goto err;                                               \
        }                                                           \
    }
 
#define NLMSG_TAIL(nmsg) \
    ((struct rtattr *)(((uint8_t *)(nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
 
#define SITNL_NEST(_msg, _max_size, _attr)              \
    ({                                                  \
        struct rtattr *_nest = NLMSG_TAIL(_msg);        \
        SITNL_ADDATTR(_msg, _max_size, _attr, NULL, 0); \
        _nest;                                          \
    })
 
#define SITNL_NEST_END(_msg, _nest)                                 \
    {                                                               \
        _nest->rta_len = (void *)NLMSG_TAIL(_msg) - (void *)_nest;  \
    }
 
typedef union {
    in_addr_t ipv4;
    struct in6_addr ipv6;
} inet_address_t;
 
struct sitnl_link_req {
    struct nlmsghdr n;
    struct ifinfomsg i;
    char buf[256];
};
 
struct sitnl_addr_req {
    struct nlmsghdr n;
    struct ifaddrmsg i;
    char buf[256];
};
 
struct sitnl_route_req {
    struct nlmsghdr n;
    struct rtmsg r;
    char buf[256];
};
 
typedef int (*sitnl_parse_reply_cb)(struct nlmsghdr *msg, void *arg);
 
struct sitnl_route_data_cb {
    unsigned int iface;
    inet_address_t gw;
};
 
static int
sitnl_addattr(struct nlmsghdr *n, int maxlen, int type, const void *data,
              int alen)
{
    int len = RTA_LENGTH(alen);
    struct rtattr *rta;
 
    if ((int)(NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len)) > maxlen)
    {
        msg(M_WARN, "%s: rtnl: message exceeded bound of %d", __func__,
            maxlen);
        return -EMSGSIZE;
    }
 
    rta = NLMSG_TAIL(n);
    rta->rta_type = type;
    rta->rta_len = len;
 
    if (!data)
    {
        memset(RTA_DATA(rta), 0, alen);
    }
    else
    {
        memcpy(RTA_DATA(rta), data, alen);
    }
 
    n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
 
    return 0;
}
 
static int
sitnl_socket(void)
{
    int sndbuf = SNDBUF_SIZE;
    int rcvbuf = RCVBUF_SIZE;
    int fd;
 
    fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
    if (fd < 0)
    {
        msg(M_WARN, "%s: cannot open netlink socket", __func__);
        return fd;
    }
 
    if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &sndbuf, sizeof(sndbuf)) < 0)
    {
        msg(M_WARN | M_ERRNO, "%s: SO_SNDBUF", __func__);
        close(fd);
        return -1;
    }
 
    if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &rcvbuf, sizeof(rcvbuf)) < 0)
    {
        msg(M_WARN | M_ERRNO, "%s: SO_RCVBUF", __func__);
        close(fd);
        return -1;
    }
 
    return fd;
}
 
static int
sitnl_bind(int fd, uint32_t groups)
{
    socklen_t addr_len;
    struct sockaddr_nl local;
 
    CLEAR(local);
 
    local.nl_family = AF_NETLINK;
    local.nl_groups = groups;
 
    if (bind(fd, (struct sockaddr *)&local, sizeof(local)) < 0)
    {
        msg(M_WARN | M_ERRNO, "%s: cannot bind netlink socket", __func__);
        return -errno;
    }
 
    addr_len = sizeof(local);
    if (getsockname(fd, (struct sockaddr *)&local, &addr_len) < 0)
    {
        msg(M_WARN | M_ERRNO, "%s: cannot getsockname", __func__);
        return -errno;
    }
 
    if (addr_len != sizeof(local))
    {
        msg(M_WARN, "%s: wrong address length %d", __func__, addr_len);
        return -EINVAL;
    }
 
    if (local.nl_family != AF_NETLINK)
    {
        msg(M_WARN, "%s: wrong address family %d", __func__, local.nl_family);
        return -EINVAL;
    }
 
    return 0;
}
 
static int
sitnl_send(struct nlmsghdr *payload, pid_t peer, unsigned int groups,
           sitnl_parse_reply_cb cb, void *arg_cb)
{
    int len, rem_len, fd, ret, rcv_len;
    struct sockaddr_nl nladdr;
    struct nlmsgerr *err;
    struct nlmsghdr *h;
    unsigned int seq;
    char buf[1024 * 16];
    struct iovec iov =
    {
        .iov_base = payload,
        .iov_len = payload->nlmsg_len,
    };
    struct msghdr nlmsg =
    {
        .msg_name = &nladdr,
        .msg_namelen = sizeof(nladdr),
        .msg_iov = &iov,
        .msg_iovlen = 1,
    };
 
    CLEAR(nladdr);
 
    nladdr.nl_family = AF_NETLINK;
    nladdr.nl_pid = peer;
    nladdr.nl_groups = groups;
 
    payload->nlmsg_seq = seq = time(NULL);
 
    /* no need to send reply */
    if (!cb)
    {
        payload->nlmsg_flags |= NLM_F_ACK;
    }
 
    fd = sitnl_socket();
    if (fd < 0)
    {
        msg(M_WARN | M_ERRNO, "%s: can't open rtnl socket", __func__);
        return -errno;
    }
 
    ret = sitnl_bind(fd, 0);
    if (ret < 0)
    {
        msg(M_WARN | M_ERRNO, "%s: can't bind rtnl socket", __func__);
        ret = -errno;
        goto out;
    }
 
    ret = sendmsg(fd, &nlmsg, 0);
    if (ret < 0)
    {
        msg(M_WARN | M_ERRNO, "%s: rtnl: error on sendmsg()", __func__);
        ret = -errno;
        goto out;
    }
 
    /* prepare buffer to store RTNL replies */
    memset(buf, 0, sizeof(buf));
    iov.iov_base = buf;
 
    while (1)
    {
        /*
         * iov_len is modified by recvmsg(), therefore has to be initialized before
         * using it again
         */
        msg(D_RTNL, "%s: checking for received messages", __func__);
        iov.iov_len = sizeof(buf);
        rcv_len = recvmsg(fd, &nlmsg, 0);
        msg(D_RTNL, "%s: rtnl: received %d bytes", __func__, rcv_len);
        if (rcv_len < 0)
        {
            if ((errno == EINTR) || (errno == EAGAIN))
            {
                msg(D_RTNL, "%s: interrupted call", __func__);
                continue;
            }
            msg(M_WARN | M_ERRNO, "%s: rtnl: error on recvmsg()", __func__);
            ret = -errno;
            goto out;
        }
 
        if (rcv_len == 0)
        {
            msg(M_WARN, "%s: rtnl: socket reached unexpected EOF", __func__);
            ret = -EIO;
            goto out;
        }
 
        if (nlmsg.msg_namelen != sizeof(nladdr))
        {
            msg(M_WARN, "%s: sender address length: %u (expected %zu)",
                __func__, nlmsg.msg_namelen, sizeof(nladdr));
            ret = -EIO;
            goto out;
        }
 
        h = (struct nlmsghdr *)buf;
        while (rcv_len >= (int)sizeof(*h))
        {
            len = h->nlmsg_len;
            rem_len = len - sizeof(*h);
 
            if ((rem_len < 0) || (len > rcv_len))
            {
                if (nlmsg.msg_flags & MSG_TRUNC)
                {
                    msg(M_WARN, "%s: truncated message", __func__);
                    ret = -EIO;
                    goto out;
                }
                msg(M_WARN, "%s: malformed message: len=%d", __func__, len);
                ret = -EIO;
                goto out;
            }
 
/*            if (((int)nladdr.nl_pid != peer) || (h->nlmsg_pid != nladdr.nl_pid)
 *               || (h->nlmsg_seq != seq))
 *           {
 *               rcv_len -= NLMSG_ALIGN(len);
 *               h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
 *               msg(M_DEBUG, "%s: skipping unrelated message. nl_pid:%d (peer:%d) nl_msg_pid:%d nl_seq:%d seq:%d",
 *                   __func__, (int)nladdr.nl_pid, peer, h->nlmsg_pid,
 *                   h->nlmsg_seq, seq);
 *               continue;
 *           }
 */
 
            if (h->nlmsg_type == NLMSG_DONE)
            {
                ret = 0;
                goto out;
            }
 
            if (h->nlmsg_type == NLMSG_ERROR)
            {
                err = (struct nlmsgerr *)NLMSG_DATA(h);
                if (rem_len < (int)sizeof(struct nlmsgerr))
                {
                    msg(M_WARN, "%s: ERROR truncated", __func__);
                    ret = -EIO;
                }
                else
                {
                    if (!err->error)
                    {
                        ret = 0;
                        if (cb)
                        {
                            int r = cb(h, arg_cb);
                            if (r <= 0)
                            {
                                ret = r;
                            }
                        }
                    }
                    else
                    {
                        msg(M_WARN, "%s: rtnl: generic error (%d): %s",
                            __func__, err->error, strerror(-err->error));
                        ret = err->error;
                    }
                }
                goto out;
            }
 
            if (cb)
            {
                int r = cb(h, arg_cb);
                if (r <= 0)
                {
                    ret = r;
                    goto out;
                }
            }
            else
            {
                msg(M_WARN, "%s: RTNL: unexpected reply", __func__);
            }
 
            rcv_len -= NLMSG_ALIGN(len);
            h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
        }
 
        if (nlmsg.msg_flags & MSG_TRUNC)
        {
            msg(M_WARN, "%s: message truncated", __func__);
            continue;
        }
 
        if (rcv_len)
        {
            msg(M_WARN, "%s: rtnl: %d not parsed bytes", __func__, rcv_len);
            ret = -1;
            goto out;
        }
    }
out:
    close(fd);
 
    return ret;
}
 
typedef struct {
    int addr_size;
    inet_address_t gw;
    char iface[IFNAMSIZ];
    bool default_only;
    unsigned int table;
} route_res_t;
 
static int
sitnl_route_save(struct nlmsghdr *n, void *arg)
{
    route_res_t *res = arg;
    struct rtmsg *r = NLMSG_DATA(n);
    struct rtattr *rta = RTM_RTA(r);
    int len = n->nlmsg_len - NLMSG_LENGTH(sizeof(*r));
    unsigned int table, ifindex = 0;
    void *gw = NULL;
 
    /* filter-out non-zero dst prefixes */
    if (res->default_only && r->rtm_dst_len != 0)
    {
        return 1;
    }
 
    /* route table, ignored with RTA_TABLE */
    table = r->rtm_table;
 
    while (RTA_OK(rta, len))
    {
        switch (rta->rta_type)
        {
            /* route interface */
            case RTA_OIF:
                ifindex = *(unsigned int *)RTA_DATA(rta);
                break;
 
            /* route prefix */
            case RTA_DST:
                break;
 
            /* GW for the route */
            case RTA_GATEWAY:
                gw = RTA_DATA(rta);
                break;
 
            /* route table */
            case RTA_TABLE:
                table = *(unsigned int *)RTA_DATA(rta);
                break;
        }
 
        rta = RTA_NEXT(rta, len);
    }
 
    /* filter out any route not coming from the selected table */
    if (res->table && res->table != table)
    {
        return 1;
    }
 
    if (!if_indextoname(ifindex, res->iface))
    {
        msg(M_WARN | M_ERRNO, "%s: rtnl: can't get ifname for index %d",
            __func__, ifindex);
        return -1;
    }
 
    if (gw)
    {
        memcpy(&res->gw, gw, res->addr_size);
    }
 
    return 0;
}
 
static int
sitnl_route_best_gw(sa_family_t af_family, const inet_address_t *dst,
                    void *best_gw, char *best_iface)
{
    struct sitnl_route_req req;
    route_res_t res;
    int ret = -EINVAL;
 
    ASSERT(best_gw);
    ASSERT(best_iface);
 
    CLEAR(req);
    CLEAR(res);
 
    req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.r));
    req.n.nlmsg_type = RTM_GETROUTE;
    req.n.nlmsg_flags = NLM_F_REQUEST;
 
    req.r.rtm_family = af_family;
 
    switch (af_family)
    {
        case AF_INET:
            res.addr_size = sizeof(in_addr_t);
            /*
             * kernel can't return 0.0.0.0/8 host route, dump all
             * the routes and filter for 0.0.0.0/0 in cb()
             */
            if (!dst || !dst->ipv4)
            {
                req.n.nlmsg_flags |= NLM_F_DUMP;
                res.default_only = true;
                res.table = RT_TABLE_MAIN;
            }
            else
            {
                req.r.rtm_dst_len = 32;
            }
            break;
 
        case AF_INET6:
            res.addr_size = sizeof(struct in6_addr);
            /* kernel can return ::/128 host route */
            req.r.rtm_dst_len = 128;
            break;
 
        default:
            /* unsupported */
            return -EINVAL;
    }
 
    SITNL_ADDATTR(&req.n, sizeof(req), RTA_DST, dst, res.addr_size);
 
    ret = sitnl_send(&req.n, 0, 0, sitnl_route_save, &res);
    if (ret < 0)
    {
        goto err;
    }
 
    /* save result in output variables */
    memcpy(best_gw, &res.gw, res.addr_size);
    strncpy(best_iface, res.iface, IFNAMSIZ);
err:
    return ret;
 
}
 
/* used by iproute2 implementation too */
int
net_route_v6_best_gw(openvpn_net_ctx_t *ctx, const struct in6_addr *dst,
                     struct in6_addr *best_gw, char *best_iface)
{
    inet_address_t dst_v6 = {0};
    char buf[INET6_ADDRSTRLEN];
    int ret;
 
    if (dst)
    {
        dst_v6.ipv6 = *dst;
    }
 
    msg(D_ROUTE, "%s query: dst %s", __func__,
        inet_ntop(AF_INET6, &dst_v6.ipv6, buf, sizeof(buf)));
 
    ret = sitnl_route_best_gw(AF_INET6, &dst_v6, best_gw, best_iface);
    if (ret < 0)
    {
        return ret;
    }
 
    msg(D_ROUTE, "%s result: via %s dev %s", __func__,
        inet_ntop(AF_INET6, best_gw, buf, sizeof(buf)), best_iface);
 
    return ret;
 
}
 
#ifdef ENABLE_SITNL
 
int
net_route_v4_best_gw(openvpn_net_ctx_t *ctx, const in_addr_t *dst,
                     in_addr_t *best_gw, char *best_iface)
{
    inet_address_t dst_v4 = {0};
    char buf[INET_ADDRSTRLEN];
    int ret;
 
    if (dst)
    {
        dst_v4.ipv4 = htonl(*dst);
    }
 
    msg(D_ROUTE, "%s query: dst %s", __func__,
        inet_ntop(AF_INET, &dst_v4.ipv4, buf, sizeof(buf)));
 
    ret = sitnl_route_best_gw(AF_INET, &dst_v4, best_gw, best_iface);
    if (ret < 0)
    {
        return ret;
    }
 
    msg(D_ROUTE, "%s result: via %s dev %s", __func__,
        inet_ntop(AF_INET, best_gw, buf, sizeof(buf)), best_iface);
 
    /* result is expected in Host Order */
    *best_gw = ntohl(*best_gw);
 
    return ret;
}
 
int
net_iface_up(openvpn_net_ctx_t *ctx, const char *iface, bool up)
{
    struct sitnl_link_req req;
    int ifindex;
 
    CLEAR(req);
 
    if (!iface)
    {
        msg(M_WARN, "%s: passed NULL interface", __func__);
        return -EINVAL;
    }
 
    ifindex = if_nametoindex(iface);
    if (ifindex == 0)
    {
        msg(M_WARN, "%s: rtnl: cannot get ifindex for %s: %s", __func__, iface,
            strerror(errno));
        return -ENOENT;
    }
 
    req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.i));
    req.n.nlmsg_flags = NLM_F_REQUEST;
    req.n.nlmsg_type = RTM_NEWLINK;
 
    req.i.ifi_family = AF_PACKET;
    req.i.ifi_index = ifindex;
    req.i.ifi_change |= IFF_UP;
    if (up)
    {
        req.i.ifi_flags |= IFF_UP;
    }
    else
    {
        req.i.ifi_flags &= ~IFF_UP;
    }
 
    msg(M_INFO, "%s: set %s %s", __func__, iface, up ? "up" : "down");
 
    return sitnl_send(&req.n, 0, 0, NULL, NULL);
}
 
int
net_iface_mtu_set(openvpn_net_ctx_t *ctx, const char *iface,
                  uint32_t mtu)
{
    struct sitnl_link_req req;
    int ifindex, ret = -1;
 
    CLEAR(req);
 
    ifindex = if_nametoindex(iface);
    if (ifindex == 0)
    {
        msg(M_WARN | M_ERRNO, "%s: rtnl: cannot get ifindex for %s", __func__,
            iface);
        return -1;
    }
 
    req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.i));
    req.n.nlmsg_flags = NLM_F_REQUEST;
    req.n.nlmsg_type = RTM_NEWLINK;
 
    req.i.ifi_family = AF_PACKET;
    req.i.ifi_index = ifindex;
 
    SITNL_ADDATTR(&req.n, sizeof(req), IFLA_MTU, &mtu, 4);
 
    msg(M_INFO, "%s: mtu %u for %s", __func__, mtu, iface);
 
    ret = sitnl_send(&req.n, 0, 0, NULL, NULL);
err:
    return ret;
}
 
int
net_addr_ll_set(openvpn_net_ctx_t *ctx, const openvpn_net_iface_t *iface,
                uint8_t *addr)
{
    struct sitnl_link_req req;
    int ifindex, ret = -1;
 
    CLEAR(req);
 
    ifindex = if_nametoindex(iface);
    if (ifindex == 0)
    {
        msg(M_WARN | M_ERRNO, "%s: rtnl: cannot get ifindex for %s", __func__,
            iface);
        return -1;
    }
 
    req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.i));
    req.n.nlmsg_flags = NLM_F_REQUEST;
    req.n.nlmsg_type = RTM_NEWLINK;
 
    req.i.ifi_family = AF_PACKET;
    req.i.ifi_index = ifindex;
 
    SITNL_ADDATTR(&req.n, sizeof(req), IFLA_ADDRESS, addr, OPENVPN_ETH_ALEN);
 
    msg(M_INFO, "%s: lladdr " MAC_FMT " for %s", __func__, MAC_PRINT_ARG(addr),
        iface);
 
    ret = sitnl_send(&req.n, 0, 0, NULL, NULL);
err:
    return ret;
}
 
static int
sitnl_addr_set(int cmd, uint32_t flags, int ifindex, sa_family_t af_family,
               const inet_address_t *local, const inet_address_t *remote,
               int prefixlen)
{
    struct sitnl_addr_req req;
    uint32_t size;
    int ret = -EINVAL;
 
    CLEAR(req);
 
    req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.i));
    req.n.nlmsg_type = cmd;
    req.n.nlmsg_flags = NLM_F_REQUEST | flags;
 
    req.i.ifa_index = ifindex;
    req.i.ifa_family = af_family;
 
    switch (af_family)
    {
        case AF_INET:
            size = sizeof(struct in_addr);
            break;
 
        case AF_INET6:
            size = sizeof(struct in6_addr);
            break;
 
        default:
            msg(M_WARN, "%s: rtnl: unknown address family %d", __func__,
                af_family);
            return -EINVAL;
    }
 
    /* if no prefixlen has been specified, assume host address */
    if (prefixlen == 0)
    {
        prefixlen = size * 8;
    }
    req.i.ifa_prefixlen = prefixlen;
 
    if (remote)
    {
        SITNL_ADDATTR(&req.n, sizeof(req), IFA_ADDRESS, remote, size);
    }
 
    if (local)
    {
        SITNL_ADDATTR(&req.n, sizeof(req), IFA_LOCAL, local, size);
    }
 
    ret = sitnl_send(&req.n, 0, 0, NULL, NULL);
    if (ret == -EEXIST)
    {
        ret = 0;
    }
err:
    return ret;
}
 
static int
sitnl_addr_ptp_add(sa_family_t af_family, const char *iface,
                   const inet_address_t *local,
                   const inet_address_t *remote)
{
    int ifindex;
 
    switch (af_family)
    {
        case AF_INET:
        case AF_INET6:
            break;
 
        default:
            return -EINVAL;
    }
 
    if (!iface)
    {
        msg(M_WARN, "%s: passed NULL interface", __func__);
        return -EINVAL;
    }
 
    ifindex = if_nametoindex(iface);
    if (ifindex == 0)
    {
        msg(M_WARN, "%s: cannot get ifindex for %s: %s", __func__, np(iface),
            strerror(errno));
        return -ENOENT;
    }
 
    return sitnl_addr_set(RTM_NEWADDR, NLM_F_CREATE | NLM_F_REPLACE, ifindex,
                          af_family, local, remote, 0);
}
 
static int
sitnl_addr_ptp_del(sa_family_t af_family, const char *iface,
                   const inet_address_t *local)
{
    int ifindex;
 
    switch (af_family)
    {
        case AF_INET:
        case AF_INET6:
            break;
 
        default:
            return -EINVAL;
    }
 
    if (!iface)
    {
        msg(M_WARN, "%s: passed NULL interface", __func__);
        return -EINVAL;
    }
 
    ifindex = if_nametoindex(iface);
    if (ifindex == 0)
    {
        msg(M_WARN | M_ERRNO, "%s: cannot get ifindex for %s", __func__, iface);
        return -ENOENT;
    }
 
    return sitnl_addr_set(RTM_DELADDR, 0, ifindex, af_family, local, NULL, 0);
}
 
static int
sitnl_route_set(int cmd, uint32_t flags, int ifindex, sa_family_t af_family,
                const void *dst, int prefixlen,
                const void *gw, enum rt_class_t table, int metric,
                enum rt_scope_t scope, int protocol, int type)
{
    struct sitnl_route_req req;
    int ret = -1, size;
 
    CLEAR(req);
 
    switch (af_family)
    {
        case AF_INET:
            size = sizeof(in_addr_t);
            break;
 
        case AF_INET6:
            size = sizeof(struct in6_addr);
            break;
 
        default:
            return -EINVAL;
    }
 
    req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.r));
    req.n.nlmsg_type = cmd;
    req.n.nlmsg_flags = NLM_F_REQUEST | flags;
 
    req.r.rtm_family = af_family;
    req.r.rtm_scope = scope;
    req.r.rtm_protocol = protocol;
    req.r.rtm_type = type;
    req.r.rtm_dst_len = prefixlen;
 
    if (table < 256)
    {
        req.r.rtm_table = table;
    }
    else
    {
        req.r.rtm_table = RT_TABLE_UNSPEC;
        SITNL_ADDATTR(&req.n, sizeof(req), RTA_TABLE, &table, 4);
    }
 
    if (dst)
    {
        SITNL_ADDATTR(&req.n, sizeof(req), RTA_DST, dst, size);
    }
 
    if (gw)
    {
        SITNL_ADDATTR(&req.n, sizeof(req), RTA_GATEWAY, gw, size);
    }
 
    if (ifindex > 0)
    {
        SITNL_ADDATTR(&req.n, sizeof(req), RTA_OIF, &ifindex, 4);
    }
 
    if (metric > 0)
    {
        SITNL_ADDATTR(&req.n, sizeof(req), RTA_PRIORITY, &metric, 4);
    }
 
    ret = sitnl_send(&req.n, 0, 0, NULL, NULL);
err:
    return ret;
}
 
static int
sitnl_addr_add(sa_family_t af_family, const char *iface,
               const inet_address_t *addr, int prefixlen)
{
    int ifindex;
 
    switch (af_family)
    {
        case AF_INET:
        case AF_INET6:
            break;
 
        default:
            return -EINVAL;
    }
 
    if (!iface)
    {
        msg(M_WARN, "%s: passed NULL interface", __func__);
        return -EINVAL;
    }
 
    ifindex = if_nametoindex(iface);
    if (ifindex == 0)
    {
        msg(M_WARN | M_ERRNO, "%s: rtnl: cannot get ifindex for %s", __func__,
            iface);
        return -ENOENT;
    }
 
    return sitnl_addr_set(RTM_NEWADDR, NLM_F_CREATE | NLM_F_REPLACE, ifindex,
                          af_family, addr, NULL, prefixlen);
}
 
static int
sitnl_addr_del(sa_family_t af_family, const char *iface, inet_address_t *addr,
               int prefixlen)
{
    int ifindex;
 
    switch (af_family)
    {
        case AF_INET:
        case AF_INET6:
            break;
 
        default:
            return -EINVAL;
    }
 
    if (!iface)
    {
        msg(M_WARN, "%s: passed NULL interface", __func__);
        return -EINVAL;
    }
 
    ifindex = if_nametoindex(iface);
    if (ifindex == 0)
    {
        msg(M_WARN | M_ERRNO, "%s: rtnl: cannot get ifindex for %s", __func__,
            iface);
        return -ENOENT;
    }
 
    return sitnl_addr_set(RTM_DELADDR, 0, ifindex, af_family, addr, NULL,
                          prefixlen);
}
 
int
net_addr_v4_add(openvpn_net_ctx_t *ctx, const char *iface,
                const in_addr_t *addr, int prefixlen)
{
    inet_address_t addr_v4 = { 0 };
    char buf[INET_ADDRSTRLEN];
 
    if (!addr)
    {
        return -EINVAL;
    }
 
    addr_v4.ipv4 = htonl(*addr);
 
    msg(M_INFO, "%s: %s/%d dev %s", __func__,
        inet_ntop(AF_INET, &addr_v4.ipv4, buf, sizeof(buf)), prefixlen, iface);
 
    return sitnl_addr_add(AF_INET, iface, &addr_v4, prefixlen);
}
 
int
net_addr_v6_add(openvpn_net_ctx_t *ctx, const char *iface,
                const struct in6_addr *addr, int prefixlen)
{
    inet_address_t addr_v6 = { 0 };
    char buf[INET6_ADDRSTRLEN];
 
    if (!addr)
    {
        return -EINVAL;
    }
 
    addr_v6.ipv6 = *addr;
 
    msg(M_INFO, "%s: %s/%d dev %s", __func__,
        inet_ntop(AF_INET6, &addr_v6.ipv6, buf, sizeof(buf)), prefixlen, iface);
 
    return sitnl_addr_add(AF_INET6, iface, &addr_v6, prefixlen);
}
 
int
net_addr_v4_del(openvpn_net_ctx_t *ctx, const char *iface,
                const in_addr_t *addr, int prefixlen)
{
    inet_address_t addr_v4 = { 0 };
    char buf[INET_ADDRSTRLEN];
 
    if (!addr)
    {
        return -EINVAL;
    }
 
    addr_v4.ipv4 = htonl(*addr);
 
    msg(M_INFO, "%s: %s dev %s", __func__,
        inet_ntop(AF_INET, &addr_v4.ipv4, buf, sizeof(buf)), iface);
 
    return sitnl_addr_del(AF_INET, iface, &addr_v4, prefixlen);
}
 
int
net_addr_v6_del(openvpn_net_ctx_t *ctx, const char *iface,
                const struct in6_addr *addr, int prefixlen)
{
    inet_address_t addr_v6 = { 0 };
    char buf[INET6_ADDRSTRLEN];
 
    if (!addr)
    {
        return -EINVAL;
    }
 
    addr_v6.ipv6 = *addr;
 
    msg(M_INFO, "%s: %s/%d dev %s", __func__,
        inet_ntop(AF_INET6, &addr_v6.ipv6, buf, sizeof(buf)), prefixlen, iface);
 
    return sitnl_addr_del(AF_INET6, iface, &addr_v6, prefixlen);
}
 
int
net_addr_ptp_v4_add(openvpn_net_ctx_t *ctx, const char *iface,
                    const in_addr_t *local, const in_addr_t *remote)
{
    inet_address_t local_v4 = { 0 };
    inet_address_t remote_v4 = { 0 };
    char buf1[INET_ADDRSTRLEN];
    char buf2[INET_ADDRSTRLEN];
 
    if (!local)
    {
        return -EINVAL;
    }
 
    local_v4.ipv4 = htonl(*local);
 
    if (remote)
    {
        remote_v4.ipv4 = htonl(*remote);
    }
 
    msg(M_INFO, "%s: %s peer %s dev %s", __func__,
        inet_ntop(AF_INET, &local_v4.ipv4, buf1, sizeof(buf1)),
        inet_ntop(AF_INET, &remote_v4.ipv4, buf2, sizeof(buf2)), iface);
 
    return sitnl_addr_ptp_add(AF_INET, iface, &local_v4, &remote_v4);
}
 
int
net_addr_ptp_v4_del(openvpn_net_ctx_t *ctx, const char *iface,
                    const in_addr_t *local, const in_addr_t *remote)
{
    inet_address_t local_v4 = { 0 };
    char buf[INET6_ADDRSTRLEN];
 
 
    if (!local)
    {
        return -EINVAL;
    }
 
    local_v4.ipv4 = htonl(*local);
 
    msg(M_INFO, "%s: %s dev %s", __func__,
        inet_ntop(AF_INET, &local_v4.ipv4, buf, sizeof(buf)), iface);
 
    return sitnl_addr_ptp_del(AF_INET, iface, &local_v4);
}
 
static int
sitnl_route_add(const char *iface, sa_family_t af_family, const void *dst,
                int prefixlen, const void *gw, uint32_t table, int metric)
{
    enum rt_scope_t scope = RT_SCOPE_UNIVERSE;
    int ifindex = 0;
 
    if (iface)
    {
        ifindex = if_nametoindex(iface);
        if (ifindex == 0)
        {
            msg(M_WARN | M_ERRNO, "%s: rtnl: can't get ifindex for %s",
                __func__, iface);
            return -ENOENT;
        }
    }
 
    if (table == 0)
    {
        table = RT_TABLE_MAIN;
    }
 
    if (!gw && iface)
    {
        scope = RT_SCOPE_LINK;
    }
 
    return sitnl_route_set(RTM_NEWROUTE, NLM_F_CREATE, ifindex,
                           af_family, dst, prefixlen, gw, table, metric, scope,
                           RTPROT_BOOT, RTN_UNICAST);
}
 
int
net_route_v4_add(openvpn_net_ctx_t *ctx, const in_addr_t *dst, int prefixlen,
                 const in_addr_t *gw, const char *iface,
                 uint32_t table, int metric)
{
    in_addr_t *dst_ptr = NULL, *gw_ptr = NULL;
    in_addr_t dst_be = 0, gw_be = 0;
    char dst_str[INET_ADDRSTRLEN];
    char gw_str[INET_ADDRSTRLEN];
 
    if (dst)
    {
        dst_be = htonl(*dst);
        dst_ptr = &dst_be;
    }
 
    if (gw)
    {
        gw_be = htonl(*gw);
        gw_ptr = &gw_be;
    }
 
    msg(D_ROUTE, "%s: %s/%d via %s dev %s table %d metric %d", __func__,
        inet_ntop(AF_INET, &dst_be, dst_str, sizeof(dst_str)),
        prefixlen, inet_ntop(AF_INET, &gw_be, gw_str, sizeof(gw_str)),
        np(iface), table, metric);
 
    return sitnl_route_add(iface, AF_INET, dst_ptr, prefixlen, gw_ptr, table,
                           metric);
}
 
int
net_route_v6_add(openvpn_net_ctx_t *ctx, const struct in6_addr *dst,
                 int prefixlen, const struct in6_addr *gw,
                 const char *iface, uint32_t table, int metric)
{
    inet_address_t dst_v6 = { 0 };
    inet_address_t gw_v6 = { 0 };
    char dst_str[INET6_ADDRSTRLEN];
    char gw_str[INET6_ADDRSTRLEN];
 
    if (dst)
    {
        dst_v6.ipv6 = *dst;
    }
 
    if (gw)
    {
        gw_v6.ipv6 = *gw;
    }
 
    msg(D_ROUTE, "%s: %s/%d via %s dev %s table %d metric %d", __func__,
        inet_ntop(AF_INET6, &dst_v6.ipv6, dst_str, sizeof(dst_str)),
        prefixlen, inet_ntop(AF_INET6, &gw_v6.ipv6, gw_str, sizeof(gw_str)),
        np(iface), table, metric);
 
    return sitnl_route_add(iface, AF_INET6, dst, prefixlen, gw, table,
                           metric);
}
 
static int
sitnl_route_del(const char *iface, sa_family_t af_family, inet_address_t *dst,
                int prefixlen, inet_address_t *gw, uint32_t table,
                int metric)
{
    int ifindex = 0;
 
    if (iface)
    {
        ifindex = if_nametoindex(iface);
        if (ifindex == 0)
        {
            msg(M_WARN | M_ERRNO, "%s: rtnl: can't get ifindex for %s",
                __func__, iface);
            return -ENOENT;
        }
    }
 
    if (table == 0)
    {
        table = RT_TABLE_MAIN;
    }
 
    return sitnl_route_set(RTM_DELROUTE, 0, ifindex, af_family, dst, prefixlen,
                           gw, table, metric, RT_SCOPE_NOWHERE, 0, 0);
}
 
int
net_route_v4_del(openvpn_net_ctx_t *ctx, const in_addr_t *dst, int prefixlen,
                 const in_addr_t *gw, const char *iface, uint32_t table,
                 int metric)
{
    inet_address_t dst_v4 = { 0 };
    inet_address_t gw_v4 = { 0 };
    char dst_str[INET_ADDRSTRLEN];
    char gw_str[INET_ADDRSTRLEN];
 
    if (dst)
    {
        dst_v4.ipv4 = htonl(*dst);
    }
 
    if (gw)
    {
        gw_v4.ipv4 = htonl(*gw);
    }
 
    msg(D_ROUTE, "%s: %s/%d via %s dev %s table %d metric %d", __func__,
        inet_ntop(AF_INET, &dst_v4.ipv4, dst_str, sizeof(dst_str)),
        prefixlen, inet_ntop(AF_INET, &gw_v4.ipv4, gw_str, sizeof(gw_str)),
        np(iface), table, metric);
 
    return sitnl_route_del(iface, AF_INET, &dst_v4, prefixlen, &gw_v4, table,
                           metric);
}
 
int
net_route_v6_del(openvpn_net_ctx_t *ctx, const struct in6_addr *dst,
                 int prefixlen, const struct in6_addr *gw,
                 const char *iface, uint32_t table, int metric)
{
    inet_address_t dst_v6 = { 0 };
    inet_address_t gw_v6 = { 0 };
    char dst_str[INET6_ADDRSTRLEN];
    char gw_str[INET6_ADDRSTRLEN];
 
    if (dst)
    {
        dst_v6.ipv6 = *dst;
    }
 
    if (gw)
    {
        gw_v6.ipv6 = *gw;
    }
 
    msg(D_ROUTE, "%s: %s/%d via %s dev %s table %d metric %d", __func__,
        inet_ntop(AF_INET6, &dst_v6.ipv6, dst_str, sizeof(dst_str)),
        prefixlen, inet_ntop(AF_INET6, &gw_v6.ipv6, gw_str, sizeof(gw_str)),
        np(iface), table, metric);
 
    return sitnl_route_del(iface, AF_INET6, &dst_v6, prefixlen, &gw_v6,
                           table, metric);
}
 
 
int
net_iface_new(openvpn_net_ctx_t *ctx, const char *iface, const char *type,
              void *arg)
{
    struct sitnl_link_req req = { };
    int ret = -1;
 
    ASSERT(iface);
 
    req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.i));
    req.n.nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_EXCL;
    req.n.nlmsg_type = RTM_NEWLINK;
 
    SITNL_ADDATTR(&req.n, sizeof(req), IFLA_IFNAME, iface, strlen(iface) + 1);
 
    struct rtattr *linkinfo = SITNL_NEST(&req.n, sizeof(req), IFLA_LINKINFO);
    SITNL_ADDATTR(&req.n, sizeof(req), IFLA_INFO_KIND, type, strlen(type) + 1);
#if defined(ENABLE_DCO)
    if (arg && (strcmp(type, "ovpn-dco") == 0))
    {
        dco_context_t *dco = arg;
        struct rtattr *data = SITNL_NEST(&req.n, sizeof(req), IFLA_INFO_DATA);
        SITNL_ADDATTR(&req.n, sizeof(req), IFLA_OVPN_MODE, &dco->ifmode,
                      sizeof(uint8_t));
        SITNL_NEST_END(&req.n, data);
    }
#endif
    SITNL_NEST_END(&req.n, linkinfo);
 
    req.i.ifi_family = AF_PACKET;
 
    msg(D_ROUTE, "%s: add %s type %s", __func__,  iface, type);
 
    ret = sitnl_send(&req.n, 0, 0, NULL, NULL);
err:
    return ret;
}
 
static int
sitnl_parse_rtattr_flags(struct rtattr *tb[], int max, struct rtattr *rta,
                         int len, unsigned short flags)
{
    unsigned short type;
 
    memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
 
    while (RTA_OK(rta, len))
    {
        type = rta->rta_type & ~flags;
 
        if ((type <= max) && (!tb[type]))
        {
            tb[type] = rta;
        }
 
        rta = RTA_NEXT(rta, len);
    }
 
    if (len)
    {
        msg(D_ROUTE, "%s: %d bytes not parsed! (rta_len=%d)", __func__, len,
            rta->rta_len);
    }
 
    return 0;
}
 
static int
sitnl_parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int len)
{
    return sitnl_parse_rtattr_flags(tb, max, rta, len, 0);
}
 
#define sitnl_parse_rtattr_nested(tb, max, rta) \
    (sitnl_parse_rtattr_flags(tb, max, RTA_DATA(rta), RTA_PAYLOAD(rta), \
                              NLA_F_NESTED))
 
static int
sitnl_type_save(struct nlmsghdr *n, void *arg)
{
    char *type = arg;
    struct ifinfomsg *ifi = NLMSG_DATA(n);
    struct rtattr *tb[IFLA_MAX + 1];
    int ret;
 
    ret = sitnl_parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), IFLA_PAYLOAD(n));
    if (ret < 0)
    {
        return ret;
    }
 
    if (tb[IFLA_LINKINFO])
    {
        struct rtattr *tb_link[IFLA_INFO_MAX + 1];
 
        ret = sitnl_parse_rtattr_nested(tb_link, IFLA_INFO_MAX,
                                        tb[IFLA_LINKINFO]);
        if (ret < 0)
        {
            return ret;
        }
 
        if (!tb_link[IFLA_INFO_KIND])
        {
            return -ENOENT;
        }
 
        strncpynt(type, RTA_DATA(tb_link[IFLA_INFO_KIND]), IFACE_TYPE_LEN_MAX);
    }
 
    return 0;
}
 
int
net_iface_type(openvpn_net_ctx_t *ctx, const char *iface,
               char type[IFACE_TYPE_LEN_MAX])
{
    struct sitnl_link_req req = { };
    int ifindex = if_nametoindex(iface);
 
    if (!ifindex)
    {
        return -errno;
    }
 
    req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.i));
    req.n.nlmsg_flags = NLM_F_REQUEST;
    req.n.nlmsg_type = RTM_GETLINK;
 
    req.i.ifi_family = AF_PACKET;
    req.i.ifi_index = ifindex;
 
    memset(type, 0, IFACE_TYPE_LEN_MAX);
 
    int ret = sitnl_send(&req.n, 0, 0, sitnl_type_save, type);
    if (ret < 0)
    {
        msg(D_ROUTE, "%s: cannot retrieve iface %s: %s (%d)", __func__, iface,
            strerror(-ret), ret);
        return ret;
    }
 
    msg(D_ROUTE, "%s: type of %s: %s", __func__, iface, type);
 
    return 0;
}
 
int
net_iface_del(openvpn_net_ctx_t *ctx, const char *iface)
{
    struct sitnl_link_req req = { };
    int ifindex = if_nametoindex(iface);
 
    if (!ifindex)
    {
        return -errno;
    }
 
    req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.i));
    req.n.nlmsg_flags = NLM_F_REQUEST;
    req.n.nlmsg_type = RTM_DELLINK;
 
    req.i.ifi_family = AF_PACKET;
    req.i.ifi_index = ifindex;
 
    msg(D_ROUTE, "%s: delete %s", __func__, iface);
 
    return sitnl_send(&req.n, 0, 0, NULL, NULL);
}
 
#endif /* !ENABLE_SITNL */
 
#endif /* TARGET_LINUX */