/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Multipath TCP
 *
 * Copyright (c) 2017 - 2019, Intel Corporation.
 */

#ifndef __NET_MPTCP_H
#define __NET_MPTCP_H

#include <linux/skbuff.h>
#include <linux/tcp.h>
#include <linux/types.h>

struct mptcp_info;
struct mptcp_sock;
struct mptcp_pm_addr_entry;
struct seq_file;

/* MPTCP sk_buff extension data */
struct mptcp_ext {
        union {
                u64     data_ack;
                u32     data_ack32;
        };
        u64             data_seq;
        u32             subflow_seq;
        u16             data_len;
        __sum16         csum;
        u8              use_map:1,
                        dsn64:1,
                        data_fin:1,
                        use_ack:1,
                        ack64:1,
                        mpc_map:1,
                        frozen:1,
                        reset_transient:1;
        u8              reset_reason:4,
                        csum_reqd:1,
                        infinite_map:1;
};

#define MPTCPOPT_HMAC_LEN       20
#define MPTCP_RM_IDS_MAX        8

struct mptcp_rm_list {
        u8 ids[MPTCP_RM_IDS_MAX];
        u8 nr;
};

struct mptcp_addr_info {
        u8                      id;
        sa_family_t             family;
        __be16                  port;
        union {
                struct in_addr  addr;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
                struct in6_addr addr6;
#endif
        };
};

struct mptcp_out_options {
#if IS_ENABLED(CONFIG_MPTCP)
        u16 suboptions;
        struct mptcp_rm_list rm_list;
        u8 join_id;
        u8 backup;
        u8 reset_reason:4,
           reset_transient:1,
           csum_reqd:1,
           allow_join_id0:1;
        union {
                struct {
                        u64 sndr_key;
                        u64 rcvr_key;
                        u64 data_seq;
                        u32 subflow_seq;
                        u16 data_len;
                        __sum16 csum;
                };
                struct {
                        struct mptcp_addr_info addr;
                        u64 ahmac;
                };
                struct {
                        struct mptcp_ext ext_copy;
                        u64 fail_seq;
                };
                struct {
                        u32 nonce;
                        u32 token;
                        u64 thmac;
                        u8 hmac[MPTCPOPT_HMAC_LEN];
                };
        };
#endif
};

#define MPTCP_SCHED_NAME_MAX    16
#define MPTCP_SCHED_MAX         128
#define MPTCP_SCHED_BUF_MAX     (MPTCP_SCHED_NAME_MAX * MPTCP_SCHED_MAX)

struct mptcp_sched_ops {
        int (*get_send)(struct mptcp_sock *msk);
        int (*get_retrans)(struct mptcp_sock *msk);

        char                    name[MPTCP_SCHED_NAME_MAX];
        struct module           *owner;
        struct list_head        list;

        void (*init)(struct mptcp_sock *msk);
        void (*release)(struct mptcp_sock *msk);
} ____cacheline_aligned_in_smp;

#define MPTCP_PM_NAME_MAX       16
#define MPTCP_PM_MAX            128
#define MPTCP_PM_BUF_MAX        (MPTCP_PM_NAME_MAX * MPTCP_PM_MAX)

struct mptcp_pm_ops {
        char                    name[MPTCP_PM_NAME_MAX];
        struct module           *owner;
        struct list_head        list;

        void (*init)(struct mptcp_sock *msk);
        void (*release)(struct mptcp_sock *msk);
} ____cacheline_aligned_in_smp;

#ifdef CONFIG_MPTCP
void mptcp_init(void);

static inline bool sk_is_mptcp(const struct sock *sk)
{
        return tcp_sk(sk)->is_mptcp;
}

static inline bool rsk_is_mptcp(const struct request_sock *req)
{
        return tcp_rsk(req)->is_mptcp;
}

static inline bool rsk_drop_req(const struct request_sock *req)
{
        return tcp_rsk(req)->is_mptcp && tcp_rsk(req)->drop_req;
}

void mptcp_space(const struct sock *ssk, int *space, int *full_space);
bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
                       unsigned int *size, struct mptcp_out_options *opts);
bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
                          struct mptcp_out_options *opts);
bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
                               unsigned int *size, unsigned int remaining,
                               struct mptcp_out_options *opts);
bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb);

void mptcp_write_options(struct tcphdr *th, __be32 *ptr, struct tcp_sock *tp,
                         struct mptcp_out_options *opts);

void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info);

/* move the skb extension owership, with the assumption that 'to' is
 * newly allocated
 */
static inline void mptcp_skb_ext_move(struct sk_buff *to,
                                      struct sk_buff *from)
{
        if (!skb_ext_exist(from, SKB_EXT_MPTCP))
                return;

        if (WARN_ON_ONCE(to->active_extensions))
                skb_ext_put(to);

        to->active_extensions = from->active_extensions;
        to->extensions = from->extensions;
        from->active_extensions = 0;
}

static inline void mptcp_skb_ext_copy(struct sk_buff *to,
                                      struct sk_buff *from)
{
        struct mptcp_ext *from_ext;

        from_ext = skb_ext_find(from, SKB_EXT_MPTCP);
        if (!from_ext)
                return;

        from_ext->frozen = 1;
        skb_ext_copy(to, from);
}

static inline bool mptcp_ext_matches(const struct mptcp_ext *to_ext,
                                     const struct mptcp_ext *from_ext)
{
        /* MPTCP always clears the ext when adding it to the skb, so
         * holes do not bother us here
         */
        return !from_ext ||
               (to_ext && from_ext &&
                !memcmp(from_ext, to_ext, sizeof(struct mptcp_ext)));
}

/* check if skbs can be collapsed.
 * MPTCP collapse is allowed if neither @to or @from carry an mptcp data
 * mapping, or if the extension of @to is the same as @from.
 * Collapsing is not possible if @to lacks an extension, but @from carries one.
 */
static inline bool mptcp_skb_can_collapse(const struct sk_buff *to,
                                          const struct sk_buff *from)
{
        return mptcp_ext_matches(skb_ext_find(to, SKB_EXT_MPTCP),
                                 skb_ext_find(from, SKB_EXT_MPTCP));
}

void mptcp_seq_show(struct seq_file *seq);
int mptcp_subflow_init_cookie_req(struct request_sock *req,
                                  const struct sock *sk_listener,
                                  struct sk_buff *skb);
struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
                                               struct sock *sk_listener,
                                               bool attach_listener);

__be32 mptcp_get_reset_option(const struct sk_buff *skb);

static inline __be32 mptcp_reset_option(const struct sk_buff *skb)
{
        if (skb_ext_exist(skb, SKB_EXT_MPTCP))
                return mptcp_get_reset_option(skb);

        return htonl(0u);
}

void mptcp_active_detect_blackhole(struct sock *sk, bool expired);
#else

static inline void mptcp_init(void)
{
}

static inline bool sk_is_mptcp(const struct sock *sk)
{
        return false;
}

static inline bool rsk_is_mptcp(const struct request_sock *req)
{
        return false;
}

static inline bool rsk_drop_req(const struct request_sock *req)
{
        return false;
}

static inline bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
                                     unsigned int *size,
                                     struct mptcp_out_options *opts)
{
        return false;
}

static inline bool mptcp_synack_options(const struct request_sock *req,
                                        unsigned int *size,
                                        struct mptcp_out_options *opts)
{
        return false;
}

static inline bool mptcp_established_options(struct sock *sk,
                                             struct sk_buff *skb,
                                             unsigned int *size,
                                             unsigned int remaining,
                                             struct mptcp_out_options *opts)
{
        return false;
}

static inline bool mptcp_incoming_options(struct sock *sk,
                                          struct sk_buff *skb)
{
        return true;
}

static inline void mptcp_skb_ext_move(struct sk_buff *to,
                                      const struct sk_buff *from)
{
}

static inline void mptcp_skb_ext_copy(struct sk_buff *to,
                                      struct sk_buff *from)
{
}

static inline bool mptcp_skb_can_collapse(const struct sk_buff *to,
                                          const struct sk_buff *from)
{
        return true;
}

static inline void mptcp_space(const struct sock *ssk, int *s, int *fs) { }
static inline void mptcp_seq_show(struct seq_file *seq) { }

static inline int mptcp_subflow_init_cookie_req(struct request_sock *req,
                                                const struct sock *sk_listener,
                                                struct sk_buff *skb)
{
        return 0; /* TCP fallback */
}

static inline struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
                                                             struct sock *sk_listener,
                                                             bool attach_listener)
{
        return NULL;
}

static inline __be32 mptcp_reset_option(const struct sk_buff *skb)  { return htonl(0u); }

static inline void mptcp_active_detect_blackhole(struct sock *sk, bool expired) { }
#endif /* CONFIG_MPTCP */

#if IS_ENABLED(CONFIG_MPTCP_IPV6)
int mptcpv6_init(void);
void mptcpv6_handle_mapped(struct sock *sk, bool mapped);
#elif IS_ENABLED(CONFIG_IPV6)
static inline int mptcpv6_init(void) { return 0; }
static inline void mptcpv6_handle_mapped(struct sock *sk, bool mapped) { }
#endif

#if defined(CONFIG_MPTCP) && defined(CONFIG_BPF_SYSCALL)
struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk);
#else
static inline struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk) { return NULL; }
#endif

#if !IS_ENABLED(CONFIG_MPTCP)
struct mptcp_sock { };
#endif

#endif /* __NET_MPTCP_H */