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      1 /*-
      2  * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * This code is derived from the Stanford/CMU enet packet filter,
      6  * (net/enet.c) distributed as part of 4.3BSD, and code contributed
      7  * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
      8  * Berkeley Laboratory.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *      This product includes software developed by the University of
     21  *      California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  *
     38  * @(#) $Header: /tcpdump/master/libpcap/sll.h,v 1.7 2002/06/11 17:04:48 itojun Exp $ (LBL)
     39  */
     40 
     41 /*
     42  * For captures on Linux cooked sockets, we construct a fake header
     43  * that includes:
     44  *
     45  *	a 2-byte "packet type" which is one of:
     46  *
     47  *		LINUX_SLL_HOST		packet was sent to us
     48  *		LINUX_SLL_BROADCAST	packet was broadcast
     49  *		LINUX_SLL_MULTICAST	packet was multicast
     50  *		LINUX_SLL_OTHERHOST	packet was sent to somebody else
     51  *		LINUX_SLL_OUTGOING	packet was sent *by* us;
     52  *
     53  *	a 2-byte Ethernet protocol field;
     54  *
     55  *	a 2-byte link-layer type;
     56  *
     57  *	a 2-byte link-layer address length;
     58  *
     59  *	an 8-byte source link-layer address, whose actual length is
     60  *	specified by the previous value.
     61  *
     62  * All fields except for the link-layer address are in network byte order.
     63  *
     64  * DO NOT change the layout of this structure, or change any of the
     65  * LINUX_SLL_ values below.  If you must change the link-layer header
     66  * for a "cooked" Linux capture, introduce a new DLT_ type (ask
     67  * "tcpdump-workers (at) tcpdump.org" for one, so that you don't give it a
     68  * value that collides with a value already being used), and use the
     69  * new header in captures of that type, so that programs that can
     70  * handle DLT_LINUX_SLL captures will continue to handle them correctly
     71  * without any change, and so that capture files with different headers
     72  * can be told apart and programs that read them can dissect the
     73  * packets in them.
     74  */
     75 
     76 /*
     77  * A DLT_LINUX_SLL fake link-layer header.
     78  */
     79 #define SLL_HDR_LEN	16		/* total header length */
     80 #define SLL_ADDRLEN	8		/* length of address field */
     81 
     82 struct sll_header {
     83 	u_int16_t sll_pkttype;		/* packet type */
     84 	u_int16_t sll_hatype;		/* link-layer address type */
     85 	u_int16_t sll_halen;		/* link-layer address length */
     86 	u_int8_t sll_addr[SLL_ADDRLEN];	/* link-layer address */
     87 	u_int16_t sll_protocol;		/* protocol */
     88 };
     89 
     90 /*
     91  * The LINUX_SLL_ values for "sll_pkttype"; these correspond to the
     92  * PACKET_ values on Linux, but are defined here so that they're
     93  * available even on systems other than Linux, and so that they
     94  * don't change even if the PACKET_ values change.
     95  */
     96 #define LINUX_SLL_HOST		0
     97 #define LINUX_SLL_BROADCAST	1
     98 #define LINUX_SLL_MULTICAST	2
     99 #define LINUX_SLL_OTHERHOST	3
    100 #define LINUX_SLL_OUTGOING	4
    101 
    102 /*
    103  * The LINUX_SLL_ values for "sll_protocol"; these correspond to the
    104  * ETH_P_ values on Linux, but are defined here so that they're
    105  * available even on systems other than Linux.  We assume, for now,
    106  * that the ETH_P_ values won't change in Linux; if they do, then:
    107  *
    108  *	if we don't translate them in "pcap-linux.c", capture files
    109  *	won't necessarily be readable if captured on a system that
    110  *	defines ETH_P_ values that don't match these values;
    111  *
    112  *	if we do translate them in "pcap-linux.c", that makes life
    113  *	unpleasant for the BPF code generator, as the values you test
    114  *	for in the kernel aren't the values that you test for when
    115  *	reading a capture file, so the fixup code run on BPF programs
    116  *	handed to the kernel ends up having to do more work.
    117  *
    118  * Add other values here as necessary, for handling packet types that
    119  * might show up on non-Ethernet, non-802.x networks.  (Not all the ones
    120  * in the Linux "if_ether.h" will, I suspect, actually show up in
    121  * captures.)
    122  */
    123 #define LINUX_SLL_P_802_3	0x0001	/* Novell 802.3 frames without 802.2 LLC header */
    124 #define LINUX_SLL_P_802_2	0x0004	/* 802.2 frames (not D/I/X Ethernet) */
    125