55c5cd3cc1
Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Dave Jones <davej@redhat.com>
65 lines
1.9 KiB
C
65 lines
1.9 KiB
C
#ifndef __LINUX_BRIDGE_EBT_AMONG_H
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#define __LINUX_BRIDGE_EBT_AMONG_H
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#include <linux/types.h>
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#define EBT_AMONG_DST 0x01
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#define EBT_AMONG_SRC 0x02
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/* Grzegorz Borowiak <grzes@gnu.univ.gda.pl> 2003
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*
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* Write-once-read-many hash table, used for checking if a given
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* MAC address belongs to a set or not and possibly for checking
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* if it is related with a given IPv4 address.
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*
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* The hash value of an address is its last byte.
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*
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* In real-world ethernet addresses, values of the last byte are
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* evenly distributed and there is no need to consider other bytes.
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* It would only slow the routines down.
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*
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* For MAC address comparison speedup reasons, we introduce a trick.
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* MAC address is mapped onto an array of two 32-bit integers.
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* This pair of integers is compared with MAC addresses in the
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* hash table, which are stored also in form of pairs of integers
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* (in `cmp' array). This is quick as it requires only two elementary
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* number comparisons in worst case. Further, we take advantage of
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* fact that entropy of 3 last bytes of address is larger than entropy
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* of 3 first bytes. So first we compare 4 last bytes of addresses and
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* if they are the same we compare 2 first.
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*
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* Yes, it is a memory overhead, but in 2003 AD, who cares?
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*/
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struct ebt_mac_wormhash_tuple {
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__u32 cmp[2];
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__be32 ip;
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};
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struct ebt_mac_wormhash {
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int table[257];
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int poolsize;
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struct ebt_mac_wormhash_tuple pool[0];
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};
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#define ebt_mac_wormhash_size(x) ((x) ? sizeof(struct ebt_mac_wormhash) \
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+ (x)->poolsize * sizeof(struct ebt_mac_wormhash_tuple) : 0)
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struct ebt_among_info {
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int wh_dst_ofs;
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int wh_src_ofs;
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int bitmask;
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};
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#define EBT_AMONG_DST_NEG 0x1
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#define EBT_AMONG_SRC_NEG 0x2
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#define ebt_among_wh_dst(x) ((x)->wh_dst_ofs ? \
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(struct ebt_mac_wormhash*)((char*)(x) + (x)->wh_dst_ofs) : NULL)
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#define ebt_among_wh_src(x) ((x)->wh_src_ofs ? \
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(struct ebt_mac_wormhash*)((char*)(x) + (x)->wh_src_ofs) : NULL)
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#define EBT_AMONG_MATCH "among"
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#endif
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