protocol.h

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/*
 * 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 protocol dispatcher.
 *
 * Version: @(#)protocol.h  1.0.2   05/07/93
 *
 * Author:  Fred N. van Kempen, <[email protected]>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 *  Changes:
 *      Alan Cox    :   Added a name field and a frag handler
 *                  field for later.
 *      Alan Cox    :   Cleaned up, and sorted types.
 *      Pedro Roque :   inet6 protocols
 */
 
#ifndef _PROTOCOL_H
#define _PROTOCOL_H

#include <linux/in6.h>
#if IS_ENABLED(CONFIG_IPV6)
#include <linux/ipv6.h>
#endif

/* This is one larger than the largest protocol value that can be
 * found in an ipv4 or ipv6 header.  Since in both cases the protocol
 * value is presented in a __u8, this is defined to be 256.
 */
#define MAX_INET_PROTOS     256

/* This is used to register protocols. */
struct net_protocol {
    void            (*early_demux)(struct sk_buff *skb);
    int         (*handler)(struct sk_buff *skb);
    void            (*err_handler)(struct sk_buff *skb, u32 info);
    int         (*gso_send_check)(struct sk_buff *skb);
    struct sk_buff         *(*gso_segment)(struct sk_buff *skb,
                           netdev_features_t features);
    struct sk_buff        **(*gro_receive)(struct sk_buff **head,
                           struct sk_buff *skb);
    int         (*gro_complete)(struct sk_buff *skb);
    unsigned int        no_policy:1,
                netns_ok:1;
};

#if IS_ENABLED(CONFIG_IPV6)
struct inet6_protocol {
    void    (*early_demux)(struct sk_buff *skb);

    int (*handler)(struct sk_buff *skb);

    void    (*err_handler)(struct sk_buff *skb,
                   struct inet6_skb_parm *opt,
                   u8 type, u8 code, int offset,
                   __be32 info);

    int (*gso_send_check)(struct sk_buff *skb);
    struct sk_buff *(*gso_segment)(struct sk_buff *skb,
                       netdev_features_t features);
    struct sk_buff **(*gro_receive)(struct sk_buff **head,
                    struct sk_buff *skb);
    int (*gro_complete)(struct sk_buff *skb);

    unsigned int    flags;  /* INET6_PROTO_xxx */
};

#define INET6_PROTO_NOPOLICY    0x1
#define INET6_PROTO_FINAL   0x2
/* This should be set for any extension header which is compatible with GSO. */
#define INET6_PROTO_GSO_EXTHDR  0x4
#endif

/* This is used to register socket interfaces for IP protocols.  */
struct inet_protosw {
    struct list_head list;

        /* These two fields form the lookup key.  */
    unsigned short   type;     /* This is the 2nd argument to socket(2). */
    unsigned short   protocol; /* This is the L4 protocol number.  */

    struct proto     *prot;
    const struct proto_ops *ops;
  
    char             no_check;   /* checksum on rcv/xmit/none? */
    unsigned char    flags;      /* See INET_PROTOSW_* below.  */
};
#define INET_PROTOSW_REUSE 0x01      /* Are ports automatically reusable? */
#define INET_PROTOSW_PERMANENT 0x02  /* Permanent protocols are unremovable. */
#define INET_PROTOSW_ICSK      0x04  /* Is this an inet_connection_sock? */

extern const struct net_protocol __rcu *inet_protos[MAX_INET_PROTOS];

#if IS_ENABLED(CONFIG_IPV6)
extern const struct inet6_protocol __rcu *inet6_protos[MAX_INET_PROTOS];
#endif

extern int  inet_add_protocol(const struct net_protocol *prot, unsigned char num);
extern int  inet_del_protocol(const struct net_protocol *prot, unsigned char num);
extern void inet_register_protosw(struct inet_protosw *p);
extern void inet_unregister_protosw(struct inet_protosw *p);

#if IS_ENABLED(CONFIG_IPV6)
extern int  inet6_add_protocol(const struct inet6_protocol *prot, unsigned char num);
extern int  inet6_del_protocol(const struct inet6_protocol *prot, unsigned char num);
extern int  inet6_register_protosw(struct inet_protosw *p);
extern void inet6_unregister_protosw(struct inet_protosw *p);
#endif

#endif  /* _PROTOCOL_H */