/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              Definitions for the UDP protocol.
 *
 * Version:     @(#)udp.h       1.0.2   04/28/93
 *
 * Author:      Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 */
#ifndef _LINUX_UDP_H
#define _LINUX_UDP_H

#include <net/inet_sock.h>
#include <linux/skbuff.h>
#include <net/netns/hash.h>
#include <uapi/linux/udp.h>

static inline struct udphdr *udp_hdr(const struct sk_buff *skb)
{
        return (struct udphdr *)skb_transport_header(skb);
}

#define UDP_HTABLE_SIZE_MIN_PERNET      128
#define UDP_HTABLE_SIZE_MIN             (IS_ENABLED(CONFIG_BASE_SMALL) ? 128 : 256)
#define UDP_HTABLE_SIZE_MAX             65536

static inline u32 udp_hashfn(const struct net *net, u32 num, u32 mask)
{
        return (num + net_hash_mix(net)) & mask;
}

enum {
        UDP_FLAGS_CORK,         /* Cork is required */
        UDP_FLAGS_NO_CHECK6_TX, /* Send zero UDP6 checksums on TX? */
        UDP_FLAGS_NO_CHECK6_RX, /* Allow zero UDP6 checksums on RX? */
        UDP_FLAGS_GRO_ENABLED,  /* Request GRO aggregation */
        UDP_FLAGS_ACCEPT_FRAGLIST,
        UDP_FLAGS_ACCEPT_L4,
        UDP_FLAGS_ENCAP_ENABLED, /* This socket enabled encap */
        UDP_FLAGS_UDPLITE_SEND_CC, /* set via udplite setsockopt */
        UDP_FLAGS_UDPLITE_RECV_CC, /* set via udplite setsockopt */
};

/* per NUMA structure for lockless producer usage. */
struct udp_prod_queue {
        struct llist_head       ll_root ____cacheline_aligned_in_smp;
        atomic_t                rmem_alloc;
};

struct udp_sock {
        /* inet_sock has to be the first member */
        struct inet_sock inet;
#define udp_port_hash           inet.sk.__sk_common.skc_u16hashes[0]
#define udp_portaddr_hash       inet.sk.__sk_common.skc_u16hashes[1]
#define udp_portaddr_node       inet.sk.__sk_common.skc_portaddr_node

        unsigned long    udp_flags;

        int              pending;       /* Any pending frames ? */
        __u8             encap_type;    /* Is this an Encapsulation socket? */

#if !IS_ENABLED(CONFIG_BASE_SMALL)
        /* For UDP 4-tuple hash */
        __u16 udp_lrpa_hash;
        struct hlist_nulls_node udp_lrpa_node;
#endif

        /*
         * Following member retains the information to create a UDP header
         * when the socket is uncorked.
         */
        __u16            len;           /* total length of pending frames */
        __u16            gso_size;
        /*
         * Fields specific to UDP-Lite.
         */
        __u16            pcslen;
        __u16            pcrlen;
        /*
         * For encapsulation sockets.
         */
        int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
        void (*encap_err_rcv)(struct sock *sk, struct sk_buff *skb, int err,
                              __be16 port, u32 info, u8 *payload);
        int (*encap_err_lookup)(struct sock *sk, struct sk_buff *skb);
        void (*encap_destroy)(struct sock *sk);

        /* GRO functions for UDP socket */
        struct sk_buff *        (*gro_receive)(struct sock *sk,
                                               struct list_head *head,
                                               struct sk_buff *skb);
        int                     (*gro_complete)(struct sock *sk,
                                                struct sk_buff *skb,
                                                int nhoff);

        struct udp_prod_queue *udp_prod_queue;

        /* udp_recvmsg try to use this before splicing sk_receive_queue */
        struct sk_buff_head     reader_queue ____cacheline_aligned_in_smp;

        /* This field is dirtied by udp_recvmsg() */
        int             forward_deficit;

        /* This fields follows rcvbuf value, and is touched by udp_recvmsg */
        int             forward_threshold;

        /* Cache friendly copy of sk->sk_peek_off >= 0 */
        bool            peeking_with_offset;

        /*
         * Accounting for the tunnel GRO fastpath.
         * Unprotected by compilers guard, as it uses space available in
         * the last UDP socket cacheline.
         */
        struct hlist_node       tunnel_list;
        struct numa_drop_counters drop_counters;
};

#define udp_test_bit(nr, sk)                    \
        test_bit(UDP_FLAGS_##nr, &udp_sk(sk)->udp_flags)
#define udp_set_bit(nr, sk)                     \
        set_bit(UDP_FLAGS_##nr, &udp_sk(sk)->udp_flags)
#define udp_test_and_set_bit(nr, sk)            \
        test_and_set_bit(UDP_FLAGS_##nr, &udp_sk(sk)->udp_flags)
#define udp_clear_bit(nr, sk)                   \
        clear_bit(UDP_FLAGS_##nr, &udp_sk(sk)->udp_flags)
#define udp_assign_bit(nr, sk, val)             \
        assign_bit(UDP_FLAGS_##nr, &udp_sk(sk)->udp_flags, val)

#define UDP_MAX_SEGMENTS        (1 << 7UL)

#define udp_sk(ptr) container_of_const(ptr, struct udp_sock, inet.sk)

static inline int udp_set_peek_off(struct sock *sk, int val)
{
        sk_set_peek_off(sk, val);
        WRITE_ONCE(udp_sk(sk)->peeking_with_offset, val >= 0);
        return 0;
}

static inline void udp_set_no_check6_tx(struct sock *sk, bool val)
{
        udp_assign_bit(NO_CHECK6_TX, sk, val);
}

static inline void udp_set_no_check6_rx(struct sock *sk, bool val)
{
        udp_assign_bit(NO_CHECK6_RX, sk, val);
}

static inline bool udp_get_no_check6_tx(const struct sock *sk)
{
        return udp_test_bit(NO_CHECK6_TX, sk);
}

static inline bool udp_get_no_check6_rx(const struct sock *sk)
{
        return udp_test_bit(NO_CHECK6_RX, sk);
}

static inline void udp_cmsg_recv(struct msghdr *msg, struct sock *sk,
                                 struct sk_buff *skb)
{
        int gso_size;

        if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) {
                gso_size = skb_shinfo(skb)->gso_size;
                put_cmsg(msg, SOL_UDP, UDP_GRO, sizeof(gso_size), &gso_size);
        }
}

DECLARE_STATIC_KEY_FALSE(udp_encap_needed_key);
#if IS_ENABLED(CONFIG_IPV6)
DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
#endif

static inline bool udp_encap_needed(void)
{
        if (static_branch_unlikely(&udp_encap_needed_key))
                return true;

#if IS_ENABLED(CONFIG_IPV6)
        if (static_branch_unlikely(&udpv6_encap_needed_key))
                return true;
#endif

        return false;
}

static inline bool udp_unexpected_gso(struct sock *sk, struct sk_buff *skb)
{
        if (!skb_is_gso(skb))
                return false;

        if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4 &&
            !udp_test_bit(ACCEPT_L4, sk))
                return true;

        if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST &&
            !udp_test_bit(ACCEPT_FRAGLIST, sk))
                return true;

        /* GSO packets lacking the SKB_GSO_UDP_TUNNEL/_CSUM bits might still
         * land in a tunnel as the socket check in udp_gro_receive cannot be
         * foolproof.
         */
        if (udp_encap_needed() &&
            READ_ONCE(udp_sk(sk)->encap_rcv) &&
            !(skb_shinfo(skb)->gso_type &
              (SKB_GSO_UDP_TUNNEL | SKB_GSO_UDP_TUNNEL_CSUM)))
                return true;

        return false;
}

static inline void udp_allow_gso(struct sock *sk)
{
        udp_set_bit(ACCEPT_L4, sk);
        udp_set_bit(ACCEPT_FRAGLIST, sk);
}

#define udp_portaddr_for_each_entry(__sk, list) \
        hlist_for_each_entry(__sk, list, __sk_common.skc_portaddr_node)

#define udp_portaddr_for_each_entry_from(__sk) \
        hlist_for_each_entry_from(__sk, __sk_common.skc_portaddr_node)

#define udp_portaddr_for_each_entry_rcu(__sk, list) \
        hlist_for_each_entry_rcu(__sk, list, __sk_common.skc_portaddr_node)

#if !IS_ENABLED(CONFIG_BASE_SMALL)
#define udp_lrpa_for_each_entry_rcu(__up, node, list) \
        hlist_nulls_for_each_entry_rcu(__up, node, list, udp_lrpa_node)
#endif

#define IS_UDPLITE(__sk) (unlikely(__sk->sk_protocol == IPPROTO_UDPLITE))

static inline struct sock *udp_tunnel_sk(const struct net *net, bool is_ipv6)
{
#if IS_ENABLED(CONFIG_NET_UDP_TUNNEL)
        return rcu_dereference(net->ipv4.udp_tunnel_gro[is_ipv6].sk);
#else
        return NULL;
#endif
}

#endif  /* _LINUX_UDP_H */