168 lines
5.0 KiB
C
168 lines
5.0 KiB
C
/****************************************************************************
|
|
*
|
|
* Copyright (C) 2006-2010 Sourcefire, Inc.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License Version 2 as
|
|
* published by the Free Software Foundation. You may not use, modify or
|
|
* distribute this program under any other version of the GNU General
|
|
* Public License.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/*
|
|
trie.h
|
|
|
|
A routing table for wordsized (32bits) bitstrings implemented as a
|
|
static level- and pathcompressed trie. For details please consult
|
|
|
|
Stefan Nilsson and Gunnar Karlsson. Fast Address Look-Up
|
|
for Internet Routers. International Conference of Broadband
|
|
Communications (BC'97).
|
|
|
|
http://www.hut.fi/~sni/papers/router/router.html
|
|
|
|
The code presented in this file has been tested with care but is
|
|
not guaranteed for any purpose. The writer does not offer any
|
|
warranties nor does he accept any liabilities with respect to
|
|
the code.
|
|
|
|
Stefan Nilsson, 4 nov 1997.
|
|
|
|
Laboratory of Information Processing Science
|
|
Helsinki University of Technology
|
|
Stefan.Nilsson@hut.fi
|
|
*/
|
|
|
|
/*
|
|
The trie is represented by an array and each node consists of an
|
|
unsigned word. The first 5 bits (31-27) indicate the logarithm
|
|
of the branching factor. The next 5 bits (26-22) indicate the
|
|
skip value. The final 22 (21-0) bits is an adress, either to
|
|
another internal node, or the base vector.
|
|
The maximum capacity is 2^21 strings (or a few more). The trie
|
|
is prefixfree. All strings that are prefixes of another string
|
|
are stored separately.
|
|
*/
|
|
|
|
#ifndef RT_TRIE_H
|
|
#define RT_TRIE_H
|
|
|
|
#define ADRSIZE 32 /* the number of bits in an address */
|
|
|
|
/* A 32-bit word is used to hold the bit patterns of
|
|
the addresses. In IPv6 this should be 128 bits.
|
|
The following typedef is machine dependent.
|
|
A word must be 32 bits long! */
|
|
typedef unsigned long word;
|
|
|
|
/* The trie is represented by an array and each node in
|
|
the trie is compactly represented using only 32 bits:
|
|
5 + 5 + 22 = branch + skip + adr */
|
|
typedef word trie_node_t;
|
|
|
|
#define NOPRE -1 /* an empty prefix pointer */
|
|
|
|
#define SETBRANCH(branch) ((branch)<<27)
|
|
#define GETBRANCH(node) ((node)>>27)
|
|
#define SETSKIP(skip) ((skip)<<22)
|
|
#define GETSKIP(node) ((node)>>22 & 037)
|
|
#define SETADR(adr) (adr)
|
|
#define GETADR(node) ((node) & 017777777)
|
|
|
|
/* extract n bits from str starting at position p */
|
|
#define EXTRACT(p, n, str) ((str)<<(p)>>(32-(n)))
|
|
|
|
/* remove the first p bits from string */
|
|
#define REMOVE(p, str) ((str)<<(p)>>(p))
|
|
|
|
/* A next-hop table entry is a 32 bit string */
|
|
|
|
typedef word policy_t;
|
|
|
|
/* The routing table entries are initially stored in
|
|
a simple array */
|
|
|
|
typedef struct entryrec *entry_t;
|
|
struct entryrec {
|
|
word data; /* the routing entry */
|
|
int len; /* and its length */
|
|
policy_t policy; /* the corresponding next-hop */
|
|
int pre; /* this auxiliary variable is used in the */
|
|
}; /* construction of the final data structure */
|
|
|
|
/* base vector */
|
|
|
|
typedef struct baserec *base_t;
|
|
struct baserec {
|
|
word str; /* the routing entry */
|
|
int len; /* and its length */
|
|
int pre; /* pointer to prefix table, -1 if no prefix */
|
|
int policy; /* pointer to next-hop table */
|
|
};
|
|
|
|
typedef struct { /* compact version of above */
|
|
word str;
|
|
int len;
|
|
int pre;
|
|
int policy;
|
|
} comp_base_t;
|
|
|
|
/* prefix vector */
|
|
|
|
typedef struct prerec *pre_t;
|
|
struct prerec {
|
|
int len; /* the length of the prefix */
|
|
int pre; /* pointer to prefix, -1 if no prefix */
|
|
int policy; /* pointer to policy table */
|
|
};
|
|
|
|
typedef struct { /* compact version of above */
|
|
int len;
|
|
int pre;
|
|
int policy;
|
|
} comp_pre_t;
|
|
|
|
/* The complete routing table data structure consists of
|
|
a trie, a base vector, a prefix vector, and a next-hop table. */
|
|
|
|
typedef struct routtablerec *routtable_t;
|
|
struct routtablerec {
|
|
trie_node_t *trie; /* the main trie search structure */
|
|
int triesize;
|
|
comp_base_t *base; /* the base vector */
|
|
int basesize;
|
|
comp_pre_t *pre; /* the prefix vector */
|
|
int presize;
|
|
policy_t *policy; /* the next-hop table */
|
|
int policysize;
|
|
|
|
int dirty; /* Whether or not the table needs to be rebuilt */
|
|
};
|
|
|
|
/* utilities */
|
|
#ifndef boolean
|
|
#ifndef HAVE_BOOLEAN
|
|
typedef unsigned char boolean;
|
|
#endif
|
|
#endif
|
|
|
|
#ifndef TRUE
|
|
# define TRUE 1
|
|
#endif
|
|
|
|
#ifndef FALSE
|
|
# define FALSE 0
|
|
#endif
|
|
|
|
#endif
|