// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/socket.h>
#include <linux/udp.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <net/dst_metadata.h>
#include <net/net_namespace.h>
#include <net/udp.h>
#include <net/udp_tunnel.h>

int udp_sock_create4(struct net *net, struct udp_port_cfg *cfg,
                     struct socket **sockp)
{
        int err;
        struct socket *sock = NULL;
        struct sockaddr_in udp_addr;

        err = sock_create_kern(net, AF_INET, SOCK_DGRAM, 0, &sock);
        if (err < 0)
                goto error;

        if (cfg->bind_ifindex) {
                err = sock_bindtoindex(sock->sk, cfg->bind_ifindex, true);
                if (err < 0)
                        goto error;
        }

        udp_addr.sin_family = AF_INET;
        udp_addr.sin_addr = cfg->local_ip;
        udp_addr.sin_port = cfg->local_udp_port;
        err = kernel_bind(sock, (struct sockaddr *)&udp_addr,
                          sizeof(udp_addr));
        if (err < 0)
                goto error;

        if (cfg->peer_udp_port) {
                udp_addr.sin_family = AF_INET;
                udp_addr.sin_addr = cfg->peer_ip;
                udp_addr.sin_port = cfg->peer_udp_port;
                err = kernel_connect(sock, (struct sockaddr *)&udp_addr,
                                     sizeof(udp_addr), 0);
                if (err < 0)
                        goto error;
        }

        sock->sk->sk_no_check_tx = !cfg->use_udp_checksums;

        *sockp = sock;
        return 0;

error:
        if (sock) {
                kernel_sock_shutdown(sock, SHUT_RDWR);
                sock_release(sock);
        }
        *sockp = NULL;
        return err;
}
EXPORT_SYMBOL(udp_sock_create4);

void setup_udp_tunnel_sock(struct net *net, struct socket *sock,
                           struct udp_tunnel_sock_cfg *cfg)
{
        struct sock *sk = sock->sk;

        /* Disable multicast loopback */
        inet_sk(sk)->mc_loop = 0;

        /* Enable CHECKSUM_UNNECESSARY to CHECKSUM_COMPLETE conversion */
        inet_inc_convert_csum(sk);

        rcu_assign_sk_user_data(sk, cfg->sk_user_data);

        udp_sk(sk)->encap_type = cfg->encap_type;
        udp_sk(sk)->encap_rcv = cfg->encap_rcv;
        udp_sk(sk)->encap_err_lookup = cfg->encap_err_lookup;
        udp_sk(sk)->encap_destroy = cfg->encap_destroy;
        udp_sk(sk)->gro_receive = cfg->gro_receive;
        udp_sk(sk)->gro_complete = cfg->gro_complete;

        udp_tunnel_encap_enable(sock);
}
EXPORT_SYMBOL_GPL(setup_udp_tunnel_sock);

void udp_tunnel_push_rx_port(struct net_device *dev, struct socket *sock,
                             unsigned short type)
{
        struct sock *sk = sock->sk;
        struct udp_tunnel_info ti;

        if (!dev->netdev_ops->ndo_udp_tunnel_add ||
            !(dev->features & NETIF_F_RX_UDP_TUNNEL_PORT))
                return;

        ti.type = type;
        ti.sa_family = sk->sk_family;
        ti.port = inet_sk(sk)->inet_sport;

        dev->netdev_ops->ndo_udp_tunnel_add(dev, &ti);
}
EXPORT_SYMBOL_GPL(udp_tunnel_push_rx_port);

void udp_tunnel_drop_rx_port(struct net_device *dev, struct socket *sock,
                             unsigned short type)
{
        struct sock *sk = sock->sk;
        struct udp_tunnel_info ti;

        if (!dev->netdev_ops->ndo_udp_tunnel_del ||
            !(dev->features & NETIF_F_RX_UDP_TUNNEL_PORT))
                return;

        ti.type = type;
        ti.sa_family = sk->sk_family;
        ti.port = inet_sk(sk)->inet_sport;

        dev->netdev_ops->ndo_udp_tunnel_del(dev, &ti);
}
EXPORT_SYMBOL_GPL(udp_tunnel_drop_rx_port);

/* Notify netdevs that UDP port started listening */
void udp_tunnel_notify_add_rx_port(struct socket *sock, unsigned short type)
{
        struct sock *sk = sock->sk;
        struct net *net = sock_net(sk);
        struct udp_tunnel_info ti;
        struct net_device *dev;

        ti.type = type;
        ti.sa_family = sk->sk_family;
        ti.port = inet_sk(sk)->inet_sport;

        rcu_read_lock();
        for_each_netdev_rcu(net, dev) {
                if (!dev->netdev_ops->ndo_udp_tunnel_add)
                        continue;
                if (!(dev->features & NETIF_F_RX_UDP_TUNNEL_PORT))
                        continue;
                dev->netdev_ops->ndo_udp_tunnel_add(dev, &ti);
        }
        rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(udp_tunnel_notify_add_rx_port);

/* Notify netdevs that UDP port is no more listening */
void udp_tunnel_notify_del_rx_port(struct socket *sock, unsigned short type)
{
        struct sock *sk = sock->sk;
        struct net *net = sock_net(sk);
        struct udp_tunnel_info ti;
        struct net_device *dev;

        ti.type = type;
        ti.sa_family = sk->sk_family;
        ti.port = inet_sk(sk)->inet_sport;

        rcu_read_lock();
        for_each_netdev_rcu(net, dev) {
                if (!dev->netdev_ops->ndo_udp_tunnel_del)
                        continue;
                if (!(dev->features & NETIF_F_RX_UDP_TUNNEL_PORT))
                        continue;
                dev->netdev_ops->ndo_udp_tunnel_del(dev, &ti);
        }
        rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(udp_tunnel_notify_del_rx_port);

void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk, struct sk_buff *skb,
                         __be32 src, __be32 dst, __u8 tos, __u8 ttl,
                         __be16 df, __be16 src_port, __be16 dst_port,
                         bool xnet, bool nocheck)
{
        struct udphdr *uh;

        __skb_push(skb, sizeof(*uh));
        skb_reset_transport_header(skb);
        uh = udp_hdr(skb);

        uh->dest = dst_port;
        uh->source = src_port;
        uh->len = htons(skb->len);

        memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));

        udp_set_csum(nocheck, skb, src, dst, skb->len);

        iptunnel_xmit(sk, rt, skb, src, dst, IPPROTO_UDP, tos, ttl, df, xnet);
}
EXPORT_SYMBOL_GPL(udp_tunnel_xmit_skb);

void udp_tunnel_sock_release(struct socket *sock)
{
        rcu_assign_sk_user_data(sock->sk, NULL);
        kernel_sock_shutdown(sock, SHUT_RDWR);
        sock_release(sock);
}
EXPORT_SYMBOL_GPL(udp_tunnel_sock_release);

struct metadata_dst *udp_tun_rx_dst(struct sk_buff *skb,  unsigned short family,
                                    __be16 flags, __be64 tunnel_id, int md_size)
{
        struct metadata_dst *tun_dst;
        struct ip_tunnel_info *info;

        if (family == AF_INET)
                tun_dst = ip_tun_rx_dst(skb, flags, tunnel_id, md_size);
        else
                tun_dst = ipv6_tun_rx_dst(skb, flags, tunnel_id, md_size);
        if (!tun_dst)
                return NULL;

        info = &tun_dst->u.tun_info;
        info->key.tp_src = udp_hdr(skb)->source;
        info->key.tp_dst = udp_hdr(skb)->dest;
        if (udp_hdr(skb)->check)
                info->key.tun_flags |= TUNNEL_CSUM;
        return tun_dst;
}
EXPORT_SYMBOL_GPL(udp_tun_rx_dst);

MODULE_LICENSE("GPL");