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/* $Id: aggregate.c,v 1.12 2002/03/06 16:55:38 jabley Exp $
*
* Copyright (c) 2000-2001 by Metromedia Fiber Network Services, Inc.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND METROMEDIA FIBER NETWORK SERVICES,
* INC. ("MFN") DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
* EVENT SHALL MFN BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
* USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*
* Metromedia Fiber Network
* 360 Hamilton Avenue
* White Plains, NY 10601
*
* http://www.mmfn.com/
*
* aggregate:
*
* Find the most general set of route prefixes which exactly
* include a supplied set. Intended to help launder peer-
* supplied route filters into a sensibly-sized list.
*
* jabley@mfnx.net
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <ctype.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/param.h>
#define MAX_buf 63
#define LESSTHAN(p,q) \
( (ntohl(p->prefix.s_addr) < ntohl(q->prefix.s_addr)) || \
(ntohl(p->prefix.s_addr) == ntohl(q->prefix.s_addr) && \
p->masklen < q->masklen) )
struct filter_list
{
struct in_addr prefix;
int masklen;
enum { origin_SUPPLIED, origin_REMOVED, origin_ADDED } origin;
int line;
struct filter_list *next;
};
int moanf(int fatal, char *fmt, ...)
{
va_list ap;
int r;
va_start(ap, fmt);
r = fprintf(stderr, "aggregate: ");
r += vfprintf(stderr, fmt, ap);
r += fprintf(stderr, "\n");
va_end(ap);
if (fatal) exit(1);
return(r);
}
/* we are rolling our own inet_aton() variant here, since the
* common libc practice of interpreting leading zeros on octets
* as octal numbers is non-intuitive, and is not compatible
* with zero-padded (decimal) data from whois.radb.net. Thanks
* to Arnold Nipper for noticing. This function was mainly
* ripped from OpenBSD source, since that's what happened to be
* handy.
*/
int my_inet_aton(const char *cp, struct in_addr *addr)
{
struct in_addr val;
int n;
char c;
u_int parts[4];
u_int *pp = parts;
c = *cp;
for (;;) {
/*
* collect number up to ``.'' Values are not specified as for C;
* preceding 0s still cause the digits to be interpreted as
* decimal, and "x" characters are illegal. This is different
* to the behaviour of the libc routine inet_aton().
*/
if (!isdigit(c))
return (0);
val.s_addr = 0;
for (;;) {
if (isdigit(c)) {
val.s_addr = (val.s_addr * 10) + (c - '0');
c = *++cp;
} else
break;
}
if (c == '.') {
/*
* Internet format:
* a.b.c.d
* a.b.c (with c treated as 16 bits)
* a.b (with b treated as 24 bits)
*/
if (pp >= parts + 3)
return (0);
*pp++ = val.s_addr;
c = *++cp;
} else
break;
}
/* Check for trailing characters. */
if (c != '\0' && (!isascii(c) || !isspace(c)))
return (0);
/* Concoct the address according to the number of parts specified. */
n = pp - parts + 1;
switch (n) {
case 0: /* initial nondigit */
return (0);
case 1: /* a -- 32 bits */
break;
case 2: /* a.b -- 8.24 bits */
if ((val.s_addr > 0xffffff) || (parts[0] > 0xff))
return (0);
val.s_addr |= parts[0] << 24;
break;
case 3: /* a.b.c -- 8.8.16 bits */
if ((val.s_addr > 0xffff) || (parts[0] > 0xff) || (parts[1] > 0xff))
return (0);
val.s_addr |= (parts[0] << 24) | (parts[1] << 16);
break;
case 4: /* a.b.c.d -- 8.8.8.8 bits */
if ((val.s_addr > 0xff) || (parts[0] > 0xff) || (parts[1] > 0xff) || \
(parts[2] > 0xff))
return (0);
val.s_addr |= (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8);
break;
}
if (addr)
addr->s_addr = htonl(val.s_addr);
return (1);
}
int main(int argc, char **argv)
{
int verbose = 0, quiet = 0, truncate = 0;
int default_prefix_length = 0;
int max_prefix_length = 32;
int max_prefix_opt = 32;
int ch, line, i, masklen, found;
struct filter_list *head, *p, *q, *r, *s;
char buf[MAX_buf + 1];
struct in_addr prefix;
/* initialise */
head = NULL;
/* parse command-line switches */
while ((ch = getopt(argc, argv, "tqvm:o:p:")) != -1)
switch (ch)
{
case 'm':
max_prefix_length = atoi(optarg);
if (max_prefix_length < 1 || max_prefix_length > 32)
moanf(1, "can't set maximum prefix length to %d", max_prefix_length);
break;
case 'o':
max_prefix_opt = atoi(optarg);
if (max_prefix_opt < 1 || max_prefix_opt > 32)
moanf(1, "can't set maximum prefix length for optimisation to %d", max_prefix_opt);
break;
case 'p':
default_prefix_length = atoi(optarg);
if (default_prefix_length < 1 || default_prefix_length > 32)
moanf(1, "can't set default prefix length to %d", \
default_prefix_length);
break;
case 'q':
quiet = 1;
break;
case 't':
truncate = 1;
break;
case 'v':
verbose = 1;
break;
case '?':
moanf(1, "Syntax: aggregate [-m max-length] [-o max-opt-length] [-p default-length] [-q] [-t] [-v]");
break;
}
if (default_prefix_length > max_prefix_length && !quiet)
moanf(0, "default prefix length (%d) is greater than maximum prefix length (%d)", \
default_prefix_length, max_prefix_length);
if (!quiet)
moanf(0, "maximum prefix length permitted will be %d", max_prefix_length);
if (max_prefix_opt > max_prefix_length && !quiet)
moanf(0, "no optimisation for prefixes longer than %d bits", max_prefix_length);
if (default_prefix_length && !quiet)
moanf(0, "prefix length of %d bits will be used where none specified", \
default_prefix_length);
/* read a list of prefixes on stdin */
line = 0;
while (fgets(buf, MAX_buf, stdin))
{
line++;
/* parse the line we just read */
if (default_prefix_length)
{
i = 0;
while (buf[i] == '.' || (buf[i] >= '0' && buf[i] <= '9') && \
i < MAX_buf) i++;
if (i == MAX_buf)
{
if (!quiet)
moanf(0, "[line %d] line too long; ignoring line", line);
continue;
}
buf[i] = 0;
masklen = default_prefix_length;
} else {
i = 0;
while (buf[i] != '/' && i < MAX_buf) i++;
if (i == MAX_buf)
{
if (!quiet)
moanf(0, "[line %d] line too long; ignoring line", line);
continue;
}
buf[i] = 0;
masklen = atoi(buf + i + 1);
if (masklen < 1 || masklen > max_prefix_length)
{
if (!quiet)
moanf(0, "[line %d] mask length %d out of range; ignoring line", \
line, masklen);
continue;
}
}
if (my_inet_aton(buf, &prefix) == 0)
{
if (!quiet)
moanf(0, "[line %d] can't parse prefix '%s'; ignoring line", line, \
buf);
continue;
}
if ((ntohl(prefix.s_addr) & (0xffffffff >> masklen)) != 0 && masklen < 32)
{
if (truncate) {
prefix.s_addr = htonl(ntohl(prefix.s_addr) & \
(0xffffffff << (32-masklen)));
if (!quiet)
moanf(0, "[line %d] prefix %s/%d truncated to %s/%d", \
line, buf, masklen, inet_ntoa(prefix), masklen);
} else {
if (!quiet)
moanf(0, "[line %d] %s/%d inconsistent; ignoring line", \
line, inet_ntoa(prefix), masklen);
continue;
}
}
/* create a list entry, and insertion sort it */
if ((p = malloc(sizeof(struct filter_list))) == NULL)
moanf(1, "[line %d] malloc() failure", line);
p->prefix.s_addr = prefix.s_addr;
p->masklen = masklen;
p->origin = origin_SUPPLIED;
p->line = line;
if (head)
{
q = head;
r = NULL;
while (LESSTHAN(q, p) && q->next)
{
r = q;
q = q->next;
}
if (LESSTHAN(q, p))
{
p->next = q->next;
q->next = p;
} else {
if (r)
{
p->next = r->next;
r->next = p;
} else {
p->next = q;
head = p;
}
}
} else {
head = p;
head->next = NULL;
}
}
if (!head) {
if (!quiet)
moanf(0, "no prefixes supplied");
exit(0);
}
/* list of prefixes is now complete; do our crude optimisations */
/* first eliminate overlapping prefixes */
p = head->next;
while (p)
{
q = head;
while (q && q != p)
{
if ((p->masklen <= max_prefix_opt) &&
(ntohl(p->prefix.s_addr) / (1<<(32 - q->masklen))) ==
(ntohl(q->prefix.s_addr) / (1<<(32 - q->masklen))))
{
p->origin = origin_REMOVED;
break;
}
q = q->next;
}
p = p->next;
}
/* now hunt for adjacent entries that can be combined */
do
{
found = 0;
p = head;
r = NULL;
while (p)
{
while (p->next && p->origin == origin_REMOVED)
p = p->next;
if (!(p->next))
break;
q = p->next;
while (q->next && q->origin == origin_REMOVED)
q = q->next;
if (q->origin == origin_REMOVED)
break;
if ( (p->masklen == q->masklen) && \
(p->masklen <= max_prefix_opt) && \
(ntohl(p->prefix.s_addr) % (2 << (32 - p->masklen)) == 0) && \
(ntohl(q->prefix.s_addr) - ntohl(p->prefix.s_addr) == \
(1 << (32 - p->masklen))))
{
if ((s = malloc(sizeof(struct filter_list))) == NULL)
moanf(1, "malloc() failure during adjacency collapse");
s->prefix = p->prefix;
s->masklen = p->masklen - 1;
s->origin = origin_ADDED;
s->next = p;
s->line = 0;
p->origin = origin_REMOVED;
q->origin = origin_REMOVED;
if (r)
r->next = s;
else
head = s;
found = 1;
break;
}
r = p;
p = p->next;
}
} while (found);
/* output the results */
p = head;
while (p)
{
if (verbose)
{
printf("[%5d] ", p->line);
switch (p->origin)
{
case origin_SUPPLIED:
putchar(' ');
break;
case origin_REMOVED:
putchar('-');
break;
case origin_ADDED:
putchar('+');
break;
}
putchar(' ');
}
if (verbose || p->origin != origin_REMOVED)
printf("%s/%d\n", inet_ntoa(p->prefix), p->masklen);
p = p->next;
}
return(0);
}
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