Re: Shortcuts to counting rules?

[Rick Jones <rick.jones2@hp.com>]

Rick Jones wrote:
> Rick Jones wrote:
> 
>> Philip Craig wrote:
>>
>>> The getsockopt() calls are part of the linux ABI.  Using them is safe.
>>> You just need to make sure you handle the case that they aren't
>>> implemented.
>>
>>
>>
>> Time to go find their documentation then I suppose.
> 
> 
> Looks like struct ipt_getinfo and ip6t_getinfo are only in header files 
> that come with "iptables-dev?"

Having found linux/netfilter_ipv4/ip_tables.h and its ipv6 counterpart, 
I will confess to having an Emily Litella moment with the above.

In messing about further and at the risk of yet another emily litella 
moment (I have no pride when I'm trying to learn something new :) with 
what the getsockopt(IPT_SO_GET_INFO) returns vs what I get by iterating 
with libiptc calls, I take it that I cannot just use num_entries from 
ipt_getinfo but have to retrieve the entries and run through them 
skipping over chain entries?

tardy:~/iptables-1.4.1.1# cc -o fw_count 
fw_count.ctardy:~/iptables-1.4.1.1# ./fw_count
name is mangle valid is 1f num is 6 size is 916
name is nat valid is 19 num is 4 size is 620
name is filter valid is e num is 4 size is 620
firewalltype is 1, rulecount 14
tardy:~/iptables-1.4.1.1# cc -DHAVE_IT_ALL -Iinclude -Llibiptc -o 
fw_count fw_count.c -liptc
tardy:~/iptables-1.4.1.1# ./fw_count
chain count 5
chain count 3
chain count 3
firewalltype is 1, rulecount 0

The "tardy" system has no rules defined, and there are five chains for 
mangle and three each for nat and filter, but that leaves me with one - 
is that expected?

tardy:~/iptables-1.4.1.1# cat fw_count.c
#if defined(HAVE_LIBIPTC_H) && defined(HAVE_IPTABLES_H) && 
defined(HAVE_LIBIPTC)
#define HAVE_IT_ALL
#endif

#include <errno.h>
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <dlfcn.h>
#include <time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

#if defined(HAVE_IT_ALL)
#include "libiptc/libiptc.h"
#include "iptables.h"
#else
/* seems linux/netfilter_ipv4/ip_tables.h needs IFNAMSIZ and does not get
  * it on its own */
#include <net/if.h>
#include <linux/netfilter_ipv4/ip_tables.h>
/* need to consider IPv6 here at some point */
#endif

#define NETFW_UNKNOWN -1
#define NETFW_IPTABLES 1


#if defined(HAVE_IT_ALL)
static int
count_rules(iptc_handle_t *messiah) {

         const char *chain;
         const struct ipt_entry *rule;
         int count = 0;
         int chain_count = 0;
         chain = iptc_first_chain(messiah);
         while (chain) {
                 chain_count++;
                 rule = iptc_first_rule(chain,messiah);
                 while (rule) {
                         count++;
                         rule = iptc_next_rule(rule,messiah);
                 }
                 chain = iptc_next_chain(messiah);
         }
         printf("chain count %d\n",chain_count);
         return count;
}
#else
static int
count_rules(char *table) {

         struct ipt_getinfo info;

         static int sock = -1;;
         int len = sizeof(info);

         if (-1 == sock)
                 sock = socket(AF_INET,SOCK_RAW,IPPROTO_RAW);
         strncpy(info.name,table,IPT_TABLE_MAXNAMELEN);
         info.name[IPT_TABLE_MAXNAMELEN-1] = '\0';

         getsockopt(sock,SOL_IP,IPT_SO_GET_INFO,&info,&len);

         printf("name is %s valid is %x num is %d size is %d\n",
                 info.name,
                 info.valid_hooks,
                 info.num_entries,
                 info.size);

         return info.num_entries;
}

#endif


void
get_firewall_info(int *firewalltype, int *rulecount) {

#if defined(HAVE_IT_ALL)
         iptc_handle_t messiah;  /* handles, always handles */
#endif

         FILE *namesfile = NULL;
         char tablename[IPT_TABLE_MAXNAMELEN + 1];
         int mycount = 0;
         *firewalltype = NETFW_IPTABLES;
         *rulecount = -1;


         namesfile = fopen("/proc/net/ip_tables_names","r");
         if (!namesfile)
                 return;

         while (fgets(tablename,
                      sizeof(tablename),
                      namesfile)) {
                 /* no end of line is bad */
                 if (tablename[strlen(tablename) - 1] != '\n') {
                         /* we want to signal the problem somehow */
                         /* so set the rulecount to -1 always here */
                         *rulecount = -1;
                         return;
                 }
                 /* but we dont want to have one in our calls */
                 tablename[strlen(tablename) - 1] = '\0';
#if defined(HAVE_IT_ALL)
                 messiah = iptc_init(tablename);
                 mycount += count_rules(&messiah);
                 iptc_free(&messiah);
#else
                 mycount += count_rules(tablename);
#endif
         }
         *rulecount = mycount;
}

int
main(int argc, char *argv[]) {

         int firewalltype,rulecount;

         get_firewall_info(&firewalltype,&rulecount);
         printf("firewalltype is %d, rulecount 
%d\n",firewalltype,rulecount);

         return 0;
}