if_arp.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.
 *
 *              Global definitions for the ARP (RFC 826) protocol.
 *
 * Version:     @(#)if_arp.h    1.0.1   04/16/93
 *
 * Authors:     Original taken from Berkeley UNIX 4.3, (c) UCB 1986-1988
 *              Portions taken from the KA9Q/NOS (v2.00m PA0GRI) source.
 *              Ross Biro, <bir7@leland.Stanford.Edu>
 *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *
 *              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 _LINUX_IF_ARP_H
#define _LINUX_IF_ARP_H

/// ARP protocol HARDWARE identifiers. 
#define ARPHRD_NETROM   0               ///< from KA9Q: NET/ROM pseudo  
#define ARPHRD_ETHER    1               ///< Ethernet 10Mbps            
#define ARPHRD_EETHER   2               ///< Experimental Ethernet      
#define ARPHRD_AX25     3               ///< AX.25 Level 2              
#define ARPHRD_PRONET   4               ///< PROnet token ring          
#define ARPHRD_CHAOS    5               ///< Chaosnet                   
#define ARPHRD_IEEE802  6               ///< IEEE 802.2 Ethernet- huh?  
#define ARPHRD_ARCNET   7               ///< ARCnet                     
#define ARPHRD_APPLETLK 8               ///< APPLEtalk                  

/// ARP protocol opcodes. 
#define ARPOP_REQUEST   1               ///< ARP request                        
#define ARPOP_REPLY     2               ///< ARP reply                  
#define ARPOP_RREQUEST  3               ///< RARP request                       
#define ARPOP_RREPLY    4               ///< RARP reply                 


/**
*

 * Address Resolution Protocol.
 *
 * See RFC 826 for protocol description.  ARP packets are variable
 * in size; the arphdr structure defines the fixed-length portion.
 * Protocol type values are the same as those for 10 Mb/s Ethernet.
 * It is followed by the variable-sized fields ar_sha, arp_spa,
 * arp_tha and arp_tpa in that order, according to the lengths
 * specified.  Field names used correspond to RFC 826.


*/
struct arphdr {
  unsigned short        ar_hrd;         ///< format of hardware address 
  unsigned short        ar_pro;         ///< format of protocol address 
  unsigned char         ar_hln;         ///< length of hardware address 
  unsigned char         ar_pln;         ///< length of protocol address 
  unsigned short        ar_op;          ///< ARP opcode (command)               

  /// The rest is variable in size, according to the sizes above. 
#if 0
  unsigned char         ar_sha[];       ///< sender hardware address    
  unsigned char         ar_spa[];       ///< sender protocol address    
  unsigned char         ar_tha[];       ///< target hardware address    
  unsigned char         ar_tpa[];       ///< target protocol address    
#endif  // not actually included! 
};


/// ARP ioctl request. 
struct arpreq {
  struct sockaddr       arp_pa;         ///< protocol address           
  struct sockaddr       arp_ha;         ///< hardware address           
  int                   arp_flags;      ///< flags                      
};

/// ARP Flag values. 
#define ATF_INUSE       0x01            ///< entry in use                       
#define ATF_COM         0x02            ///< completed entry (ha valid) 
#define ATF_PERM        0x04            ///< permanent entry            
#define ATF_PUBL        0x08            ///< publish entry              
#define ATF_USETRAILERS 0x10            ///< has requested trailers     


#endif  // _LINUX_IF_ARP_H 

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