ip.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 IP module.
 *
 * Version: @(#)ip.h    1.0.2   05/07/93
 *
 * Authors: Ross Biro
 *      Fred N. van Kempen, <[email protected]>
 *      Alan Cox, <[email protected]>
 *
 * Changes:
 *      Mike McLagan    :       Routing by source
 *
 *      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.
 */
#ifndef _IP_H
#define _IP_H

#include <linux/types.h>
#include <linux/ip.h>
#include <linux/in.h>
#include <linux/skbuff.h>

#include <net/inet_sock.h>
#include <net/snmp.h>
#include <net/flow.h>

struct sock;

struct inet_skb_parm {
    struct ip_options   opt;        /* Compiled IP options      */
    unsigned char       flags;

#define IPSKB_FORWARDED     1
#define IPSKB_XFRM_TUNNEL_SIZE  2
#define IPSKB_XFRM_TRANSFORMED  4
#define IPSKB_FRAG_COMPLETE 8
#define IPSKB_REROUTED      16

    u16         frag_max_size;
};

static inline unsigned int ip_hdrlen(const struct sk_buff *skb)
{
    return ip_hdr(skb)->ihl * 4;
}

struct ipcm_cookie {
    __be32          addr;
    int         oif;
    struct ip_options_rcu   *opt;
    __u8            tx_flags;
};

#define IPCB(skb) ((struct inet_skb_parm*)((skb)->cb))

struct ip_ra_chain {
    struct ip_ra_chain __rcu *next;
    struct sock     *sk;
    union {
        void            (*destructor)(struct sock *);
        struct sock     *saved_sk;
    };
    struct rcu_head     rcu;
};

extern struct ip_ra_chain __rcu *ip_ra_chain;

/* IP flags. */
#define IP_CE       0x8000      /* Flag: "Congestion"       */
#define IP_DF       0x4000      /* Flag: "Don't Fragment"   */
#define IP_MF       0x2000      /* Flag: "More Fragments"   */
#define IP_OFFSET   0x1FFF      /* "Fragment Offset" part   */

#define IP_FRAG_TIME    (30 * HZ)       /* fragment lifetime    */

struct msghdr;
struct net_device;
struct packet_type;
struct rtable;
struct sockaddr;

extern int      igmp_mc_proc_init(void);

/*
 *  Functions provided by ip.c
 */

extern int      ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
                          __be32 saddr, __be32 daddr,
                          struct ip_options_rcu *opt);
extern int      ip_rcv(struct sk_buff *skb, struct net_device *dev,
                   struct packet_type *pt, struct net_device *orig_dev);
extern int      ip_local_deliver(struct sk_buff *skb);
extern int      ip_mr_input(struct sk_buff *skb);
extern int      ip_output(struct sk_buff *skb);
extern int      ip_mc_output(struct sk_buff *skb);
extern int      ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *));
extern int      ip_do_nat(struct sk_buff *skb);
extern void     ip_send_check(struct iphdr *ip);
extern int      __ip_local_out(struct sk_buff *skb);
extern int      ip_local_out(struct sk_buff *skb);
extern int      ip_queue_xmit(struct sk_buff *skb, struct flowi *fl);
extern void     ip_init(void);
extern int      ip_append_data(struct sock *sk, struct flowi4 *fl4,
                       int getfrag(void *from, char *to, int offset, int len,
                           int odd, struct sk_buff *skb),
                void *from, int len, int protolen,
                struct ipcm_cookie *ipc,
                struct rtable **rt,
                unsigned int flags);
extern int      ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb);
extern ssize_t      ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
                int offset, size_t size, int flags);
extern struct sk_buff  *__ip_make_skb(struct sock *sk,
                      struct flowi4 *fl4,
                      struct sk_buff_head *queue,
                      struct inet_cork *cork);
extern int      ip_send_skb(struct net *net, struct sk_buff *skb);
extern int      ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4);
extern void     ip_flush_pending_frames(struct sock *sk);
extern struct sk_buff  *ip_make_skb(struct sock *sk,
                    struct flowi4 *fl4,
                    int getfrag(void *from, char *to, int offset, int len,
                        int odd, struct sk_buff *skb),
                    void *from, int length, int transhdrlen,
                    struct ipcm_cookie *ipc,
                    struct rtable **rtp,
                    unsigned int flags);

static inline struct sk_buff *ip_finish_skb(struct sock *sk, struct flowi4 *fl4)
{
    return __ip_make_skb(sk, fl4, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
}

/* datagram.c */
extern int      ip4_datagram_connect(struct sock *sk, 
                         struct sockaddr *uaddr, int addr_len);

struct ip_reply_arg {
    struct kvec iov[1];   
    int     flags;
    __wsum      csum;
    int     csumoffset; /* u16 offset of csum in iov[0].iov_base */
                /* -1 if not needed */ 
    int     bound_dev_if;
    u8          tos;
}; 

#define IP_REPLY_ARG_NOSRCCHECK 1

static inline __u8 ip_reply_arg_flowi_flags(const struct ip_reply_arg *arg)
{
    return (arg->flags & IP_REPLY_ARG_NOSRCCHECK) ? FLOWI_FLAG_ANYSRC : 0;
}

void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
               __be32 saddr, const struct ip_reply_arg *arg,
               unsigned int len);

struct ipv4_config {
    int log_martians;
    int no_pmtu_disc;
};

extern struct ipv4_config ipv4_config;
#define IP_INC_STATS(net, field)    SNMP_INC_STATS64((net)->mib.ip_statistics, field)
#define IP_INC_STATS_BH(net, field) SNMP_INC_STATS64_BH((net)->mib.ip_statistics, field)
#define IP_ADD_STATS(net, field, val)   SNMP_ADD_STATS64((net)->mib.ip_statistics, field, val)
#define IP_ADD_STATS_BH(net, field, val) SNMP_ADD_STATS64_BH((net)->mib.ip_statistics, field, val)
#define IP_UPD_PO_STATS(net, field, val) SNMP_UPD_PO_STATS64((net)->mib.ip_statistics, field, val)
#define IP_UPD_PO_STATS_BH(net, field, val) SNMP_UPD_PO_STATS64_BH((net)->mib.ip_statistics, field, val)
#define NET_INC_STATS(net, field)   SNMP_INC_STATS((net)->mib.net_statistics, field)
#define NET_INC_STATS_BH(net, field)    SNMP_INC_STATS_BH((net)->mib.net_statistics, field)
#define NET_INC_STATS_USER(net, field)  SNMP_INC_STATS_USER((net)->mib.net_statistics, field)
#define NET_ADD_STATS_BH(net, field, adnd) SNMP_ADD_STATS_BH((net)->mib.net_statistics, field, adnd)
#define NET_ADD_STATS_USER(net, field, adnd) SNMP_ADD_STATS_USER((net)->mib.net_statistics, field, adnd)

extern unsigned long snmp_fold_field(void __percpu *mib[], int offt);
#if BITS_PER_LONG==32
extern u64 snmp_fold_field64(void __percpu *mib[], int offt, size_t sync_off);
#else
static inline u64 snmp_fold_field64(void __percpu *mib[], int offt, size_t syncp_off)
{
    return snmp_fold_field(mib, offt);
}
#endif
extern int snmp_mib_init(void __percpu *ptr[2], size_t mibsize, size_t align);
extern void snmp_mib_free(void __percpu *ptr[2]);

extern struct local_ports {
    seqlock_t   lock;
    int     range[2];
} sysctl_local_ports;
extern void inet_get_local_port_range(int *low, int *high);

extern unsigned long *sysctl_local_reserved_ports;
static inline int inet_is_reserved_local_port(int port)
{
    return test_bit(port, sysctl_local_reserved_ports);
}

extern int sysctl_ip_nonlocal_bind;

/* From inetpeer.c */
extern int inet_peer_threshold;
extern int inet_peer_minttl;
extern int inet_peer_maxttl;

/* From ip_input.c */
extern int sysctl_ip_early_demux;

/* From ip_output.c */
extern int sysctl_ip_dynaddr;

extern void ipfrag_init(void);

extern void ip_static_sysctl_init(void);

static inline bool ip_is_fragment(const struct iphdr *iph)
{
    return (iph->frag_off & htons(IP_MF | IP_OFFSET)) != 0;
}

#ifdef CONFIG_INET
#include <net/dst.h>

/* The function in 2.2 was invalid, producing wrong result for
 * check=0xFEFF. It was noticed by Arthur Skawina _year_ ago. --ANK(000625) */
static inline
int ip_decrease_ttl(struct iphdr *iph)
{
    u32 check = (__force u32)iph->check;
    check += (__force u32)htons(0x0100);
    iph->check = (__force __sum16)(check + (check>=0xFFFF));
    return --iph->ttl;
}

static inline
int ip_dont_fragment(struct sock *sk, struct dst_entry *dst)
{
    return  inet_sk(sk)->pmtudisc == IP_PMTUDISC_DO ||
        (inet_sk(sk)->pmtudisc == IP_PMTUDISC_WANT &&
         !(dst_metric_locked(dst, RTAX_MTU)));
}

extern void __ip_select_ident(struct iphdr *iph, struct dst_entry *dst, int more);

static inline void ip_select_ident(struct iphdr *iph, struct dst_entry *dst, struct sock *sk)
{
    if (iph->frag_off & htons(IP_DF)) {
        /* This is only to work around buggy Windows95/2000
         * VJ compression implementations.  If the ID field
         * does not change, they drop every other packet in
         * a TCP stream using header compression.
         */
        iph->id = (sk && inet_sk(sk)->inet_daddr) ?
                    htons(inet_sk(sk)->inet_id++) : 0;
    } else
        __ip_select_ident(iph, dst, 0);
}

static inline void ip_select_ident_more(struct iphdr *iph, struct dst_entry *dst, struct sock *sk, int more)
{
    if (iph->frag_off & htons(IP_DF)) {
        if (sk && inet_sk(sk)->inet_daddr) {
            iph->id = htons(inet_sk(sk)->inet_id);
            inet_sk(sk)->inet_id += 1 + more;
        } else
            iph->id = 0;
    } else
        __ip_select_ident(iph, dst, more);
}

/*
 *  Map a multicast IP onto multicast MAC for type ethernet.
 */

static inline void ip_eth_mc_map(__be32 naddr, char *buf)
{
    __u32 addr=ntohl(naddr);
    buf[0]=0x01;
    buf[1]=0x00;
    buf[2]=0x5e;
    buf[5]=addr&0xFF;
    addr>>=8;
    buf[4]=addr&0xFF;
    addr>>=8;
    buf[3]=addr&0x7F;
}

/*
 *  Map a multicast IP onto multicast MAC for type IP-over-InfiniBand.
 *  Leave P_Key as 0 to be filled in by driver.
 */

static inline void ip_ib_mc_map(__be32 naddr, const unsigned char *broadcast, char *buf)
{
    __u32 addr;
    unsigned char scope = broadcast[5] & 0xF;

    buf[0]  = 0;        /* Reserved */
    buf[1]  = 0xff;     /* Multicast QPN */
    buf[2]  = 0xff;
    buf[3]  = 0xff;
    addr    = ntohl(naddr);
    buf[4]  = 0xff;
    buf[5]  = 0x10 | scope; /* scope from broadcast address */
    buf[6]  = 0x40;     /* IPv4 signature */
    buf[7]  = 0x1b;
    buf[8]  = broadcast[8];     /* P_Key */
    buf[9]  = broadcast[9];
    buf[10] = 0;
    buf[11] = 0;
    buf[12] = 0;
    buf[13] = 0;
    buf[14] = 0;
    buf[15] = 0;
    buf[19] = addr & 0xff;
    addr  >>= 8;
    buf[18] = addr & 0xff;
    addr  >>= 8;
    buf[17] = addr & 0xff;
    addr  >>= 8;
    buf[16] = addr & 0x0f;
}

static inline void ip_ipgre_mc_map(__be32 naddr, const unsigned char *broadcast, char *buf)
{
    if ((broadcast[0] | broadcast[1] | broadcast[2] | broadcast[3]) != 0)
        memcpy(buf, broadcast, 4);
    else
        memcpy(buf, &naddr, sizeof(naddr));
}

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

static __inline__ void inet_reset_saddr(struct sock *sk)
{
    inet_sk(sk)->inet_rcv_saddr = inet_sk(sk)->inet_saddr = 0;
#if IS_ENABLED(CONFIG_IPV6)
    if (sk->sk_family == PF_INET6) {
        struct ipv6_pinfo *np = inet6_sk(sk);

        memset(&np->saddr, 0, sizeof(np->saddr));
        memset(&np->rcv_saddr, 0, sizeof(np->rcv_saddr));
    }
#endif
}

#endif

static inline int sk_mc_loop(struct sock *sk)
{
    if (!sk)
        return 1;
    switch (sk->sk_family) {
    case AF_INET:
        return inet_sk(sk)->mc_loop;
#if IS_ENABLED(CONFIG_IPV6)
    case AF_INET6:
        return inet6_sk(sk)->mc_loop;
#endif
    }
    WARN_ON(1);
    return 1;
}

extern bool ip_call_ra_chain(struct sk_buff *skb);

/*
 *  Functions provided by ip_fragment.c
 */

enum ip_defrag_users {
    IP_DEFRAG_LOCAL_DELIVER,
    IP_DEFRAG_CALL_RA_CHAIN,
    IP_DEFRAG_CONNTRACK_IN,
    __IP_DEFRAG_CONNTRACK_IN_END    = IP_DEFRAG_CONNTRACK_IN + USHRT_MAX,
    IP_DEFRAG_CONNTRACK_OUT,
    __IP_DEFRAG_CONNTRACK_OUT_END   = IP_DEFRAG_CONNTRACK_OUT + USHRT_MAX,
    IP_DEFRAG_CONNTRACK_BRIDGE_IN,
    __IP_DEFRAG_CONNTRACK_BRIDGE_IN = IP_DEFRAG_CONNTRACK_BRIDGE_IN + USHRT_MAX,
    IP_DEFRAG_VS_IN,
    IP_DEFRAG_VS_OUT,
    IP_DEFRAG_VS_FWD,
    IP_DEFRAG_AF_PACKET,
    IP_DEFRAG_MACVLAN,
};

int ip_defrag(struct sk_buff *skb, u32 user);
#ifdef CONFIG_INET
struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user);
#else
static inline struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user)
{
    return skb;
}
#endif
int ip_frag_mem(struct net *net);
int ip_frag_nqueues(struct net *net);

/*
 *  Functions provided by ip_forward.c
 */
 
extern int ip_forward(struct sk_buff *skb);
 
/*
 *  Functions provided by ip_options.c
 */
 
extern void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
                 __be32 daddr, struct rtable *rt, int is_frag);
extern int ip_options_echo(struct ip_options *dopt, struct sk_buff *skb);
extern void ip_options_fragment(struct sk_buff *skb);
extern int ip_options_compile(struct net *net,
                  struct ip_options *opt, struct sk_buff *skb);
extern int ip_options_get(struct net *net, struct ip_options_rcu **optp,
              unsigned char *data, int optlen);
extern int ip_options_get_from_user(struct net *net, struct ip_options_rcu **optp,
                    unsigned char __user *data, int optlen);
extern void ip_options_undo(struct ip_options * opt);
extern void ip_forward_options(struct sk_buff *skb);
extern int ip_options_rcv_srr(struct sk_buff *skb);

/*
 *  Functions provided by ip_sockglue.c
 */

extern void ipv4_pktinfo_prepare(struct sk_buff *skb);
extern void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb);
extern int  ip_cmsg_send(struct net *net,
                 struct msghdr *msg, struct ipcm_cookie *ipc);
extern int  ip_setsockopt(struct sock *sk, int level, int optname, char __user *optval, unsigned int optlen);
extern int  ip_getsockopt(struct sock *sk, int level, int optname, char __user *optval, int __user *optlen);
extern int  compat_ip_setsockopt(struct sock *sk, int level,
            int optname, char __user *optval, unsigned int optlen);
extern int  compat_ip_getsockopt(struct sock *sk, int level,
            int optname, char __user *optval, int __user *optlen);
extern int  ip_ra_control(struct sock *sk, unsigned char on, void (*destructor)(struct sock *));

extern int  ip_recv_error(struct sock *sk, struct msghdr *msg, int len);
extern void ip_icmp_error(struct sock *sk, struct sk_buff *skb, int err, 
                  __be16 port, u32 info, u8 *payload);
extern void ip_local_error(struct sock *sk, int err, __be32 daddr, __be16 dport,
                   u32 info);

#ifdef CONFIG_PROC_FS
extern int ip_misc_proc_init(void);
#endif

#endif  /* _IP_H */