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tcpdump/ether.h

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The "__attribute__((packed))" tag on structures causes some files not to compile with Sun C, as "interface.h" isn't being included before the structures are being declared. Furthermore, in the files that Sun C *can* compile, it doesn't cause Sun C to generate code that's safe with unaligned accesses, as "__attribute__" is defined as a do-nothing macro with compilers that don't support it. Therefore, we get rid of that tag on the structures to which it was added, and instead use "EXTRACT_16BIT()" and "EXTRACT_32BIT()" to fetch 16-bit and 32-bit big-endian quantities from packets. We also fix some other references to multi-byte quantities to get rid of code that tries to do unaligned loads on platforms that don't support them. We also throw in a hack that makes those macros use "__attribute__((packed))" on structures containing only one 16-bit or 32-bit integer to get the compiler to generate unaligned-safe code rather than doing it by hand. (GCC on SPARC produces the same code that doing it by hand does; I don't know if GCC on any other big-endian strict-alignment processor generates better code for that case. On little-endian processors, as "ntohs()" and "ntohl()" might be functions, that might actually produce worse code.) Fix some places to use "%u" rather than "%d" to print unsigned quantities.
2002-12-11 15:13:49 +08:00
/* @(#) $Header: /tcpdump/master/tcpdump/ether.h,v 1.8 2002-12-11 07:13:51 guy Exp $ (LBL) */
Add definitions of Ethernet types from "linux-includes/netinet/if_ether.h" to "ethertype.h". Move other stuff used by dissectors from <netinet/if_ether.h> to "ether.h", along the lines of "fddi.h" and "token.h". Move ARP declarations from BSD include files to "print-arp.c". Remove from dissectors includes of <netinet/if_ether.h>, and add includes of "ethertype.h" and/or "ether.h" as necessary. Get rid of configuration options that test declarations now made in "ether.h" or "print-arp.c", as those declarations are now under our control, not the OS's control.
2000-09-23 16:03:27 +08:00
/*
* Copyright (c) 1982, 1986, 1993
* The Regents of the University of California. 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)if_ether.h 8.3 (Berkeley) 5/2/95
*/
#define ETHERMTU 1500
/*
* The number of bytes in an ethernet (MAC) address.
*/
#define ETHER_ADDR_LEN 6
/*
Some compilers may pad structures to a length that's a multiple of 2 or 4 bytes, even though no member in the structure requires such an alignment; don't use "sizeof (struct ether_header)" or "sizeof (struct fddi_header)", explicitly #define the header length and use that #defined value.
2000-10-09 10:59:39 +08:00
* Structure of a DEC/Intel/Xerox or 802.3 Ethernet header.
Add definitions of Ethernet types from "linux-includes/netinet/if_ether.h" to "ethertype.h". Move other stuff used by dissectors from <netinet/if_ether.h> to "ether.h", along the lines of "fddi.h" and "token.h". Move ARP declarations from BSD include files to "print-arp.c". Remove from dissectors includes of <netinet/if_ether.h>, and add includes of "ethertype.h" and/or "ether.h" as necessary. Get rid of configuration options that test declarations now made in "ether.h" or "print-arp.c", as those declarations are now under our control, not the OS's control.
2000-09-23 16:03:27 +08:00
*/
struct ether_header {
always use u_intXX_t for protocol format declaration. char/short/int may not come with exact size. while at it, correct signedness of ip/udp header field. nuke most of the use of bitfield. TODO: bitfield in namser.h
2000-10-03 10:54:54 +08:00
u_int8_t ether_dhost[ETHER_ADDR_LEN];
u_int8_t ether_shost[ETHER_ADDR_LEN];
u_int16_t ether_type;
The "__attribute__((packed))" tag on structures causes some files not to compile with Sun C, as "interface.h" isn't being included before the structures are being declared. Furthermore, in the files that Sun C *can* compile, it doesn't cause Sun C to generate code that's safe with unaligned accesses, as "__attribute__" is defined as a do-nothing macro with compilers that don't support it. Therefore, we get rid of that tag on the structures to which it was added, and instead use "EXTRACT_16BIT()" and "EXTRACT_32BIT()" to fetch 16-bit and 32-bit big-endian quantities from packets. We also fix some other references to multi-byte quantities to get rid of code that tries to do unaligned loads on platforms that don't support them. We also throw in a hack that makes those macros use "__attribute__((packed))" on structures containing only one 16-bit or 32-bit integer to get the compiler to generate unaligned-safe code rather than doing it by hand. (GCC on SPARC produces the same code that doing it by hand does; I don't know if GCC on any other big-endian strict-alignment processor generates better code for that case. On little-endian processors, as "ntohs()" and "ntohl()" might be functions, that might actually produce worse code.) Fix some places to use "%u" rather than "%d" to print unsigned quantities.
2002-12-11 15:13:49 +08:00
};
Some compilers may pad structures to a length that's a multiple of 2 or 4 bytes, even though no member in the structure requires such an alignment; don't use "sizeof (struct ether_header)" or "sizeof (struct fddi_header)", explicitly #define the header length and use that #defined value.
2000-10-09 10:59:39 +08:00
/*
* Length of a DEC/Intel/Xerox or 802.3 Ethernet header; note that some
* compilers may pad "struct ether_header" to a multiple of 4 bytes,
* for example, so "sizeof (struct ether_header)" may not give the right
* answer.
*/
#define ETHER_HDRLEN 14
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