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/* filter generator, ipfilter driver
*
* Copyright (c) 2002 Matthew Kirkwood
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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
*/
/* TODO:
* - does this need skeleton routines?
* - implement grouping
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "filter.h"
#include "util.h"
static char *appip(char *r, const struct addr_spec *h) {
if (!h->addrstr)
return APPS(r, "any");
APPS(r, h->addrstr);
if (h->maskstr)
APP2(r, "/", h->maskstr);
return r;
}
static char *appport(char *r, const struct port_spec *p, int neg) {
if (!p->minstr)
return r;
APPS(r, "port");
if (!p->maxstr)
return APPSS2(r, neg ? "!=" : "=", p->minstr);
APPS(r, p->minstr);
APPSS2(r, neg ? "><" : "<>", p->maxstr);
return r;
}
static char *appicmp(char *r, const char *h, int neg) {
if (!h)
return r;
if (neg)
APPS(r, "!");
return APPSS2(r, "icmp-type", h);
}
static int cb_ipfilter_rule(const struct filterent *ent,
struct fg_misc *misc __attribute__((unused))) {
char *rule = NULL;
/* target first */
switch (ent->target) {
case T_ACCEPT:
APP(rule, "pass");
break;
case DROP:
APP(rule, "block");
break;
case T_REJECT:
/* XXX - can this violate the rule about icmp errors
* about icmp errors? */
if (ent->proto.num == IPPROTO_TCP)
APP(rule, "block return-rst");
else
APP(rule, "block return-icmp-as-dest(port-unr)");
break;
default:
fprintf(stderr, "invalid target: %d\n", ent->target);
return -1;
}
/* in or out? */
switch (ent->direction) {
case INPUT:
APPS(rule, "in");
break;
case OUTPUT:
APPS(rule, "out");
break;
default:
fprintf(stderr, "invalid direction: %d\n", ent->direction);
return -1;
}
if (ESET(ent, LOG))
APPS(rule, "log");
/* XXX - All our rules have to be "quick", but ipfilter
* people seem to prefer having defaults at the top.
* It would be nice to improve the output readability.
*/
APPS(rule, "quick");
/* access list name */
if (ent->iface)
APPSS2(rule, "on", ent->iface);
/* protocol */
if (ent->proto.name)
APPSS2(rule, "proto", ent->proto.name);
APPS(rule, "from");
rule = appip(rule, &ent->srcaddr);
rule = appport(rule, &ent->u.ports.src, NEG(SPORT));
APPS(rule, "to");
rule = appip(rule, &ent->dstaddr);
rule = appport(rule, &ent->u.ports.dst, NEG(DPORT));
rule = appicmp(rule, ent->u.icmp, NEG(ICMPTYPE));
if (ent->proto.name && (ent->target == T_ACCEPT) && !ent->oneway)
APPS(rule, "keep state");
oputs(rule);
free(rule);
return 1;
}
int fg_ipfilter(struct filter *filter, int flags) {
struct fg_misc misc = {flags, NULL};
fg_callback cb_ipfilter = {.rule = cb_ipfilter_rule, NULL};
filter_nogroup(filter);
filter_unroll(&filter);
return filtergen_cprod(filter, &cb_ipfilter, &misc);
}
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