FreeBSD/Linux Kernel Cross Reference
sys/netinet/libalias/alias.h

     /* lint -save -library Flexelint comment for external headers */
     
     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * 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.
     *
     * $FreeBSD$
     */
    
    /*
     * Alias.h defines the outside world interfaces for the packet aliasing
     * software.
     *
     * This software is placed into the public domain with no restrictions on its
     * distribution.
     */
    
    #ifndef _ALIAS_H_
    #define _ALIAS_H_
    
    #include <netinet/in_systm.h>
    #include <netinet/in.h>
    #include <netinet/ip.h>
    
    #define LIBALIAS_BUF_SIZE 128
    #ifdef _KERNEL
    /*
     * The kernel version of libalias does not support these features.
     */
    #define NO_FW_PUNCH
    #define NO_USE_SOCKETS
    #endif
    
    /*
     * The external interface to libalias, the packet aliasing engine.
     *
     * There are two sets of functions:
     *
     * PacketAlias*() the old API which doesn't take an instance pointer
     * and therefore can only have one packet engine at a time.
     *
     * LibAlias*() the new API which takes as first argument a pointer to
     * the instance of the packet aliasing engine.
     *
     * The functions otherwise correspond to each other one for one, except
     * for the LibAliasUnaliasOut()/PacketUnaliasOut() function which were
     * were misnamed in the old API.
     */
    
    /*
     * The instance structure
     */
    struct libalias;
    
    /*
     * An anonymous structure, a pointer to which is returned from
     * PacketAliasRedirectAddr(), PacketAliasRedirectPort() or
     * PacketAliasRedirectProto(), passed to PacketAliasAddServer(),
     * and freed by PacketAliasRedirectDelete().
     */
    struct alias_link;
    
    /* Initialization and control functions. */
    struct libalias *LibAliasInit(struct libalias *);
    void            LibAliasSetAddress(struct libalias *, struct in_addr _addr);
    void            LibAliasSetAliasPortRange(struct libalias *la, u_short port_low, u_short port_hi);
    void            LibAliasSetFWBase(struct libalias *, unsigned int _base, unsigned int _num);
    void            LibAliasSetSkinnyPort(struct libalias *, unsigned int _port);
    unsigned int    LibAliasSetMode(struct libalias *, unsigned int _flags, unsigned int _mask);
    void            LibAliasUninit(struct libalias *);
    
    /* Packet Handling functions. */
    int             LibAliasIn (struct libalias *, void *_ptr, int _maxpacketsize);
    int             LibAliasOut(struct libalias *, void *_ptr, int _maxpacketsize);
    int             LibAliasOutTry(struct libalias *, void *_ptr, int _maxpacketsize, int _create);
    int             LibAliasUnaliasOut(struct libalias *, void *_ptr, int _maxpacketsize);
   
   /* Port and address redirection functions. */
   
   int             LibAliasAddServer(struct libalias *, struct alias_link *_lnk,
                       struct in_addr _addr, unsigned short _port);
   struct alias_link * LibAliasRedirectAddr(struct libalias *, struct in_addr _src_addr,
                       struct in_addr _alias_addr);
   int             LibAliasRedirectDynamic(struct libalias *, struct alias_link *_lnk);
   void            LibAliasRedirectDelete(struct libalias *, struct alias_link *_lnk);
   struct alias_link * LibAliasRedirectPort(struct libalias *, struct in_addr _src_addr,
                       unsigned short _src_port, struct in_addr _dst_addr,
                       unsigned short _dst_port, struct in_addr _alias_addr,
                       unsigned short _alias_port, unsigned char _proto);
   struct alias_link * LibAliasRedirectProto(struct libalias *, struct in_addr _src_addr,
                       struct in_addr _dst_addr, struct in_addr _alias_addr,
                       unsigned char _proto);
   
   /* Fragment Handling functions. */
   void            LibAliasFragmentIn(struct libalias *, void *_ptr, void *_ptr_fragment);
   void           *LibAliasGetFragment(struct libalias *, void *_ptr);
   int             LibAliasSaveFragment(struct libalias *, void *_ptr);
   
   /* Miscellaneous functions. */
   unsigned short  LibAliasInternetChecksum(struct libalias *, unsigned short *_ptr, int _nbytes);
   void            LibAliasSetTarget(struct libalias *, struct in_addr _target_addr);
   
   /* Transparent proxying routines. */
   int             LibAliasProxyRule(struct libalias *, const char *_cmd);
   
   /* Module handling API */
   int             LibAliasLoadModule(char *);
   int             LibAliasUnLoadAllModule(void);
   int             LibAliasRefreshModules(void);
   
   /* Mbuf helper function. */
   struct mbuf    *m_megapullup(struct mbuf *, int);
   
   /*
    * Mode flags and other constants.
    */
   
   /* Mode flags, set using PacketAliasSetMode() */
   
   /*
    * If PKT_ALIAS_LOG is set, a message will be printed to /var/log/alias.log
    * every time a link is created or deleted.  This is useful for debugging.
    */
   #define PKT_ALIAS_LOG                   0x01
   
   /*
    * If PKT_ALIAS_DENY_INCOMING is set, then incoming connections (e.g. to ftp,
    * telnet or web servers will be prevented by the aliasing mechanism.
    */
   #define PKT_ALIAS_DENY_INCOMING         0x02
   
   /*
    * If PKT_ALIAS_SAME_PORTS is set, packets will be attempted sent from the
    * same port as they originated on.  This allows e.g. rsh to work *99% of the
    * time*, but _not_ 100% (it will be slightly flakey instead of not working
    * at all).  This mode bit is set by PacketAliasInit(), so it is a default
    * mode of operation.
    */
   #define PKT_ALIAS_SAME_PORTS            0x04
   
   /*
    * If PKT_ALIAS_USE_SOCKETS is set, then when partially specified links (e.g.
    * destination port and/or address is zero), the packet aliasing engine will
    * attempt to allocate a socket for the aliasing port it chooses.  This will
    * avoid interference with the host machine.  Fully specified links do not
    * require this.  This bit is set after a call to PacketAliasInit(), so it is
    * a default mode of operation.
    */
   #ifndef NO_USE_SOCKETS
   #define PKT_ALIAS_USE_SOCKETS           0x08
   #endif
   /*-
    * If PKT_ALIAS_UNREGISTERED_ONLY is set, then only packets with
    * unregistered source addresses will be aliased.  Private
    * addresses are those in the following ranges:
    *
    *              10.0.0.0     ->   10.255.255.255
    *              172.16.0.0   ->   172.31.255.255
    *              192.168.0.0  ->   192.168.255.255
    */
   #define PKT_ALIAS_UNREGISTERED_ONLY     0x10
   
   /*
    * If PKT_ALIAS_RESET_ON_ADDR_CHANGE is set, then the table of dynamic
    * aliasing links will be reset whenever PacketAliasSetAddress() changes the
    * default aliasing address.  If the default aliasing address is left
    * unchanged by this function call, then the table of dynamic aliasing links
    * will be left intact.  This bit is set after a call to PacketAliasInit().
    */
   #define PKT_ALIAS_RESET_ON_ADDR_CHANGE  0x20
   
   /*
    * If PKT_ALIAS_PROXY_ONLY is set, then NAT will be disabled and only
    * transparent proxying is performed.
    */
   #define PKT_ALIAS_PROXY_ONLY            0x40
   
   /*
    * If PKT_ALIAS_REVERSE is set, the actions of PacketAliasIn() and
    * PacketAliasOut() are reversed.
    */
   #define PKT_ALIAS_REVERSE               0x80
   
   #ifndef NO_FW_PUNCH
   /*
    * If PKT_ALIAS_PUNCH_FW is set, active FTP and IRC DCC connections will
    * create a 'hole' in the firewall to allow the transfers to work.  The
    * ipfw rule number that the hole is created with is controlled by
    * PacketAliasSetFWBase().  The hole will be attached to that
    * particular alias_link, so when the link goes away the hole is deleted.
    */
   #define PKT_ALIAS_PUNCH_FW              0x100
   #endif
   
   /*
    * If PKT_ALIAS_SKIP_GLOBAL is set, nat instance is not checked for matching
    * states in 'ipfw nat global' rule.
    */
   #define PKT_ALIAS_SKIP_GLOBAL           0x200
   
   /*
    * Like PKT_ALIAS_UNREGISTERED_ONLY, but includes the RFC 6598
    * (Carrier Grade NAT) address range as follows:
    *
    *              100.64.0.0   ->   100.127.255.255
    */
   #define PKT_ALIAS_UNREGISTERED_CGN      0x400
   
   /* Function return codes. */
   #define PKT_ALIAS_ERROR                 -1
   #define PKT_ALIAS_OK                    1
   #define PKT_ALIAS_IGNORED               2
   #define PKT_ALIAS_UNRESOLVED_FRAGMENT   3
   #define PKT_ALIAS_FOUND_HEADER_FRAGMENT 4
   
   #endif                          /* !_ALIAS_H_ */
   
   /* lint -restore */

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