/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2001 Charles Mott <cm@linktel.net>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Alias_local.h contains the function prototypes for alias.c,
 * alias_db.c, alias_util.c and alias_ftp.c, alias_irc.c (as well
 * as any future add-ons).  It also includes macros, globals and
 * struct definitions shared by more than one alias*.c file.
 *
 * This include file is intended to be used only within the aliasing
 * software.  Outside world interfaces are defined in alias.h
 *
 * This software is placed into the public domain with no restrictions
 * on its distribution.
 *
 * Initial version:  August, 1996  (cjm)
 *
 * <updated several times by original author and Eivind Eklund>
 */

#ifndef _ALIAS_LOCAL_H_
#define _ALIAS_LOCAL_H_

#include <sys/tree.h>
#include <sys/types.h>
#include <sys/sysctl.h>

#ifdef _KERNEL
#include <sys/malloc.h>
#include <sys/param.h>
#include <sys/lock.h>
#include <sys/mutex.h>

/* XXX: LibAliasSetTarget() uses this constant. */
#define INADDR_NONE     0xffffffff

#include <netinet/libalias/alias_sctp.h>
#else
#include "alias_sctp.h"
#endif

/* Sizes of input and output link tables */
#define GET_ALIAS_PORT          -1
#define GET_ALIAS_ID            GET_ALIAS_PORT

#ifdef _KERNEL
#define INET_NTOA_BUF(buf) (buf)
#else
#define INET_NTOA_BUF(buf) (buf), sizeof(buf)
#endif

struct proxy_entry;

struct group_in {
        struct in_addr  alias_addr;
        u_short         alias_port;
        int             link_type;
        SPLAY_ENTRY(group_in)   in;
        LIST_HEAD(, alias_link) full, partial;
};

struct libalias {
        LIST_ENTRY(libalias) instancelist;
        /* Mode flags documented in alias.h */
        int             packetAliasMode;
        /* Address written onto source field of IP packet. */
        struct in_addr  aliasAddress;
        /* IP address incoming packets are sent to
         * if no aliasing link already exists */
        struct in_addr  targetAddress;
        /* Lookup table of pointers to chains of link records.
         * Each link record is indexed into input,
         * output and "internal endpoint" lookup tables. */
        SPLAY_HEAD(splay_out, alias_link) linkSplayOut;
        SPLAY_HEAD(splay_in,  group_in)   linkSplayIn;
        SPLAY_HEAD(splay_internal_endpoint, alias_link)
            linkSplayInternalEndpoint;
        LIST_HEAD (, alias_link) pptpList;
        /* HouseKeeping */
        TAILQ_HEAD    (, alias_link) checkExpire;
        /* Link statistics */
        unsigned int    icmpLinkCount;
        unsigned int    udpLinkCount;
        unsigned int    tcpLinkCount;
        unsigned int    pptpLinkCount;
        unsigned int    protoLinkCount;
        unsigned int    fragmentIdLinkCount;
        unsigned int    fragmentPtrLinkCount;
        unsigned int    sockCount;
        /* log descriptor */
#ifdef _KERNEL
        char           *logDesc;
#else
        FILE           *logDesc;
#endif

#ifndef NO_FW_PUNCH
        /* File descriptor to be able to control firewall.
         * Opened by PacketAliasSetMode on first setting
         * the PKT_ALIAS_PUNCH_FW flag. */
        int             fireWallFD;
        /* The first firewall entry free for our use */
        int             fireWallBaseNum;
        /* How many entries can we use? */
        int             fireWallNumNums;
        /* Which entry did we last use? */
        int             fireWallActiveNum;
        /* bool array for entries */
        char           *fireWallField;
#endif
        /* TCP port used by the Skinny protocol. */
        unsigned int    skinnyPort;

        struct proxy_entry *proxyList;

        struct in_addr  true_addr;      /* in network byte order. */
        u_short         true_port;      /* in host byte order. */

        /* Port ranges for aliasing. */
        u_short         aliasPortLower;
        u_short         aliasPortLength;

        /*
         * sctp code support
         */

        /* counts associations that have progressed to UP and not yet removed */
        int             sctpLinkCount;
#ifdef _KERNEL
        /* timing queue for keeping track of association timeouts */
        struct sctp_nat_timer sctpNatTimer;
        /* size of hash table used in this instance */
        u_int sctpNatTableSize;
        /* local look up table sorted by l_vtag/l_port */
        LIST_HEAD(sctpNatTableL, sctp_nat_assoc) *sctpTableLocal;
        /* global look up table sorted by g_vtag/g_port */
        LIST_HEAD(sctpNatTableG, sctp_nat_assoc) *sctpTableGlobal;

        /* avoid races in libalias: every public function has to use it. */
        struct mtx mutex;
#endif
};

/* Macros */

#ifdef _KERNEL
#define LIBALIAS_LOCK_INIT(l) \
        mtx_init(&l->mutex, "per-instance libalias mutex", NULL, MTX_DEF)
#define LIBALIAS_LOCK_ASSERT(l) mtx_assert(&l->mutex, MA_OWNED)
#define LIBALIAS_LOCK(l) mtx_lock(&l->mutex)
#define LIBALIAS_UNLOCK(l) mtx_unlock(&l->mutex)
#define LIBALIAS_LOCK_DESTROY(l)        mtx_destroy(&l->mutex)
#else
#define LIBALIAS_LOCK_INIT(l)
#define LIBALIAS_LOCK_ASSERT(l)
#define LIBALIAS_LOCK(l)
#define LIBALIAS_UNLOCK(l)
#define LIBALIAS_LOCK_DESTROY(l)
#endif

/*
 * The following macro is used to update an
 * internet checksum.  "delta" is a 32-bit
 * accumulation of all the changes to the
 * checksum (adding in new 16-bit words and
 * subtracting out old words), and "cksum"
 * is the checksum value to be updated.
 */
#define ADJUST_CHECKSUM(acc, cksum) \
        do { \
                acc += cksum; \
                if (acc < 0) { \
                        acc = -acc; \
                        acc = (acc >> 16) + (acc & 0xffff); \
                        acc += acc >> 16; \
                        cksum = (u_short) ~acc; \
                } else { \
                        acc = (acc >> 16) + (acc & 0xffff); \
                        acc += acc >> 16; \
                        cksum = (u_short) acc; \
                } \
        } while (0)

/* Prototypes */

/* System time in seconds for current packet */
extern int LibAliasTime;

/*
 * SctpFunction prototypes
 *
 */
void AliasSctpInit(struct libalias *la);
void AliasSctpTerm(struct libalias *la);
int SctpAlias(struct libalias *la, struct ip *ip, int direction);

/*
 * We do not calculate TCP checksums when libalias is a kernel
 * module, since it has no idea about checksum offloading.
 * If TCP data has changed, then we just set checksum to zero,
 * and caller must recalculate it himself.
 * In case if libalias will edit UDP data, the same approach
 * should be used.
 */
#ifndef _KERNEL
u_short         IpChecksum(struct ip *_pip);
u_short         TcpChecksum(struct ip *_pip);
#endif
void
DifferentialChecksum(u_short * _cksum, void * _new, void * _old, int _n);

/* Internal data access */
struct alias_link *
AddLink(struct libalias *la, struct in_addr src_addr, struct in_addr dst_addr,
    struct in_addr alias_addr, u_short src_port, u_short dst_port,
    int alias_param, int link_type);
int
FindIcmpIn(struct libalias *la, struct in_addr _dst_addr, struct in_addr _alias_addr,
    u_short _id_alias, int _create, struct alias_link **_lnkp);
int
FindIcmpOut(struct libalias *la, struct in_addr _src_addr, struct in_addr _dst_addr,
    u_short _id, int _create, struct alias_link **_lnkp);
struct alias_link *
FindFragmentIn1(struct libalias *la, struct in_addr _dst_addr, struct in_addr _alias_addr,
    u_short _ip_id);
struct alias_link *
FindFragmentIn2(struct libalias *la, struct in_addr _dst_addr, struct in_addr _alias_addr,
    u_short _ip_id);
struct alias_link *
AddFragmentPtrLink(struct libalias *la, struct in_addr _dst_addr, u_short _ip_id);
struct alias_link *
FindFragmentPtr(struct libalias *la, struct in_addr _dst_addr, u_short _ip_id);
int
FindProtoIn(struct libalias *la, struct in_addr _dst_addr, struct in_addr _alias_addr,
    u_char _proto, struct alias_link **_lnkp);
int
FindProtoOut(struct libalias *la, struct in_addr _src_addr, struct in_addr _dst_addr,
    u_char _proto, struct alias_link **_lnkp);
int
FindUdpTcpIn(struct libalias *la, struct in_addr _dst_addr, struct in_addr _alias_addr,
    u_short _dst_port, u_short _alias_port, u_char _proto, int _create,
    struct alias_link **_lnkp);
int
FindUdpTcpOut(struct libalias *la, struct in_addr _src_addr, struct in_addr _dst_addr,
    u_short _src_port, u_short _dst_port, u_char _proto, int _create,
    struct alias_link **_lnkp);
struct alias_link *
AddPptp(struct libalias *la, struct in_addr _src_addr, struct in_addr _dst_addr,
    struct in_addr _alias_addr, u_int16_t _src_call_id);
struct alias_link *
FindPptpOutByCallId(struct libalias *la, struct in_addr _src_addr,
    struct in_addr _dst_addr, u_int16_t _src_call_id);
struct alias_link *
FindPptpInByCallId(struct libalias *la, struct in_addr _dst_addr,
    struct in_addr _alias_addr, u_int16_t _dst_call_id);
struct alias_link *
FindPptpOutByPeerCallId(struct libalias *la, struct in_addr _src_addr,
    struct in_addr _dst_addr, u_int16_t _dst_call_id);
struct alias_link *
FindPptpInByPeerCallId(struct libalias *la, struct in_addr _dst_addr,
    struct in_addr _alias_addr, u_int16_t _alias_call_id);
struct alias_link *
FindRtspOut(struct libalias *la, struct in_addr _src_addr, struct in_addr _dst_addr,
    u_short _src_port, u_short _alias_port, u_char _proto);
struct in_addr
FindOriginalAddress(struct libalias *la, struct in_addr _alias_addr);
struct in_addr
FindAliasAddress(struct libalias *la, struct in_addr _original_addr);
struct in_addr
FindSctpRedirectAddress(struct libalias *la,  struct sctp_nat_msg *sm);

/* External data access/modification */
int             FindNewPortGroup(struct libalias *la, struct in_addr _dst_addr,
                    struct in_addr _alias_addr, u_short _src_port,
                    u_short _dst_port, u_short _port_count, u_char _proto,
                    u_char _align);
void            GetFragmentAddr(struct alias_link *_lnk, struct in_addr *_src_addr);
void            SetFragmentAddr(struct alias_link *_lnk, struct in_addr _src_addr);
void            GetFragmentPtr(struct alias_link *_lnk, void **_fptr);
void            SetFragmentPtr(struct alias_link *_lnk, void *fptr);
void            SetStateIn(struct alias_link *_lnk, int _state);
void            SetStateOut(struct alias_link *_lnk, int _state);
int             GetStateIn (struct alias_link *_lnk);
int             GetStateOut(struct alias_link *_lnk);
struct in_addr  GetOriginalAddress(struct alias_link *_lnk);
struct in_addr  GetDestAddress(struct alias_link *_lnk);
struct in_addr  GetAliasAddress(struct alias_link *_lnk);
struct in_addr  GetDefaultAliasAddress(struct libalias *la);
void            SetDefaultAliasAddress(struct libalias *la, struct in_addr _alias_addr);
u_short         GetOriginalPort(struct alias_link *_lnk);
u_short         GetAliasPort(struct alias_link *_lnk);
struct in_addr  GetProxyAddress(struct alias_link *_lnk);
void            SetProxyAddress(struct alias_link *_lnk, struct in_addr _addr);
u_short         GetProxyPort(struct alias_link *_lnk);
void            SetProxyPort(struct alias_link *_lnk, u_short _port);
void            SetAckModified(struct alias_link *_lnk);
int             GetAckModified(struct alias_link *_lnk);
int             GetDeltaAckIn(u_long, struct alias_link *_lnk);
int             GetDeltaSeqOut(u_long, struct alias_link *lnk);
void            AddSeq(struct alias_link *lnk, int delta, u_int ip_hl,
                    u_short ip_len, u_long th_seq, u_int th_off);
void            SetExpire (struct alias_link *_lnk, int _expire);
void            SetProtocolFlags(struct alias_link *_lnk, int _pflags);
int             GetProtocolFlags(struct alias_link *_lnk);
void            SetDestCallId(struct alias_link *_lnk, u_int16_t _cid);

#ifndef NO_FW_PUNCH
void            PunchFWHole(struct alias_link *_lnk);

#endif

/* Housekeeping function */
void            HouseKeeping(struct libalias *);

/* Transparent proxy routines */
int
ProxyCheck(struct libalias *la, struct in_addr *proxy_server_addr,
    u_short * proxy_server_port, struct in_addr src_addr,
    struct in_addr dst_addr, u_short dst_port, u_char ip_p);
void
ProxyModify(struct libalias *la, struct alias_link *_lnk, struct ip *_pip,
    int _maxpacketsize, int _proxy_type);

/* Tcp specific routines */
/* lint -save -library Suppress flexelint warnings */

enum alias_tcp_state {
        ALIAS_TCP_STATE_NOT_CONNECTED,
        ALIAS_TCP_STATE_CONNECTED,
        ALIAS_TCP_STATE_DISCONNECTED
};

#if defined(_NETINET_IP_H_)
static __inline void *
ip_next(struct ip *iphdr)
{
        char *p = (char *)iphdr;
        return (&p[iphdr->ip_hl * 4]);
}
#endif

#if defined(_NETINET_TCP_H_)
static __inline void *
tcp_next(struct tcphdr *tcphdr)
{
        char *p = (char *)tcphdr;
        return (&p[tcphdr->th_off * 4]);
}
#endif

#if defined(_NETINET_UDP_H_)
static __inline void *
udp_next(struct udphdr *udphdr)
{
        return ((void *)(udphdr + 1));
}
#endif

#endif                          /* !_ALIAS_LOCAL_H_ */