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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/linux/netfilter_bridge/ebt_among.h | |
download | op-kernel-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip op-kernel-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'include/linux/netfilter_bridge/ebt_among.h')
-rw-r--r-- | include/linux/netfilter_bridge/ebt_among.h | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/include/linux/netfilter_bridge/ebt_among.h b/include/linux/netfilter_bridge/ebt_among.h new file mode 100644 index 0000000..307c1fe --- /dev/null +++ b/include/linux/netfilter_bridge/ebt_among.h @@ -0,0 +1,65 @@ +#ifndef __LINUX_BRIDGE_EBT_AMONG_H +#define __LINUX_BRIDGE_EBT_AMONG_H + +#define EBT_AMONG_DST 0x01 +#define EBT_AMONG_SRC 0x02 + +/* Grzegorz Borowiak <grzes@gnu.univ.gda.pl> 2003 + * + * Write-once-read-many hash table, used for checking if a given + * MAC address belongs to a set or not and possibly for checking + * if it is related with a given IPv4 address. + * + * The hash value of an address is its last byte. + * + * In real-world ethernet addresses, values of the last byte are + * evenly distributed and there is no need to consider other bytes. + * It would only slow the routines down. + * + * For MAC address comparison speedup reasons, we introduce a trick. + * MAC address is mapped onto an array of two 32-bit integers. + * This pair of integers is compared with MAC addresses in the + * hash table, which are stored also in form of pairs of integers + * (in `cmp' array). This is quick as it requires only two elementary + * number comparisons in worst case. Further, we take advantage of + * fact that entropy of 3 last bytes of address is larger than entropy + * of 3 first bytes. So first we compare 4 last bytes of addresses and + * if they are the same we compare 2 first. + * + * Yes, it is a memory overhead, but in 2003 AD, who cares? + */ + +struct ebt_mac_wormhash_tuple +{ + uint32_t cmp[2]; + uint32_t ip; +}; + +struct ebt_mac_wormhash +{ + int table[257]; + int poolsize; + struct ebt_mac_wormhash_tuple pool[0]; +}; + +#define ebt_mac_wormhash_size(x) ((x) ? sizeof(struct ebt_mac_wormhash) \ + + (x)->poolsize * sizeof(struct ebt_mac_wormhash_tuple) : 0) + +struct ebt_among_info +{ + int wh_dst_ofs; + int wh_src_ofs; + int bitmask; +}; + +#define EBT_AMONG_DST_NEG 0x1 +#define EBT_AMONG_SRC_NEG 0x2 + +#define ebt_among_wh_dst(x) ((x)->wh_dst_ofs ? \ + (struct ebt_mac_wormhash*)((char*)(x) + (x)->wh_dst_ofs) : NULL) +#define ebt_among_wh_src(x) ((x)->wh_src_ofs ? \ + (struct ebt_mac_wormhash*)((char*)(x) + (x)->wh_src_ofs) : NULL) + +#define EBT_AMONG_MATCH "among" + +#endif |