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/* Shared library add-on to iptables to add AH support. */
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <errno.h>
#include <iptables.h>
#include <linux/netfilter_ipv4/ipt_ah.h>
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"AH v%s options:\n"
" --ahspi [!] spi[:spi]\n"
" match spi (range)\n",
NETFILTER_VERSION);
}
static struct option opts[] = {
{ "ahspi", 1, 0, '1' },
{0}
};
static u_int32_t
parse_ah_spi(const char *spistr)
{
unsigned long int spi;
char* ep;
spi = strtoul(spistr,&ep,0) ;
if ( spistr == ep ) {
exit_error(PARAMETER_PROBLEM,
"AH no valid digits in spi `%s'", spistr);
}
if ( spi == ULONG_MAX && errno == ERANGE ) {
exit_error(PARAMETER_PROBLEM,
"spi `%s' specified too big: would overflow", spistr);
}
if ( *spistr != '\0' && *ep != '\0' ) {
exit_error(PARAMETER_PROBLEM,
"AH error parsing spi `%s'", spistr);
}
return (u_int32_t) spi;
}
static void
parse_ah_spis(const char *spistring, u_int32_t *spis)
{
char *buffer;
char *cp;
buffer = strdup(spistring);
if ((cp = strchr(buffer, ':')) == NULL)
spis[0] = spis[1] = parse_ah_spi(buffer);
else {
*cp = '\0';
cp++;
spis[0] = buffer[0] ? parse_ah_spi(buffer) : 0;
spis[1] = cp[0] ? parse_ah_spi(cp) : 0xFFFFFFFF;
}
free(buffer);
}
/* Initialize the match. */
static void
init(struct ipt_entry_match *m, unsigned int *nfcache)
{
struct ipt_ah *ahinfo = (struct ipt_ah *)m->data;
ahinfo->spis[1] = 0xFFFFFFFF;
}
#define AH_SPI 0x01
/* Function which parses command options; returns true if it
ate an option */
static int
parse(int c, char **argv, int invert, unsigned int *flags,
const struct ipt_entry *entry,
unsigned int *nfcache,
struct ipt_entry_match **match)
{
struct ipt_ah *ahinfo = (struct ipt_ah *)(*match)->data;
switch (c) {
case '1':
if (*flags & AH_SPI)
exit_error(PARAMETER_PROBLEM,
"Only one `--spi' allowed");
if (check_inverse(optarg, &invert))
optind++;
parse_ah_spis(argv[optind-1], ahinfo->spis);
if (invert)
ahinfo->invflags |= IPT_AH_INV_SPI;
*flags |= AH_SPI;
break;
default:
return 0;
}
return 1;
}
/* Final check; we don't care. */
static void
final_check(unsigned int flags)
{
}
static void
print_spis(const char *name, u_int32_t min, u_int32_t max,
int invert)
{
const char *inv = invert ? "!" : "";
if (min != 0 || max != 0xFFFFFFFF || invert) {
printf("%s", name);
if (min == max) {
printf(":%s", inv);
printf("%u", min);
} else {
printf("s:%s", inv);
printf("%u",min);
printf(":");
printf("%u",max);
}
printf(" ");
}
}
/* Prints out the union ipt_matchinfo. */
static void
print(const struct ipt_ip *ip,
const struct ipt_entry_match *match, int numeric)
{
const struct ipt_ah *ah = (struct ipt_ah *)match->data;
printf("ah ");
print_spis("spi", ah->spis[0], ah->spis[1],
ah->invflags & IPT_AH_INV_SPI);
if (ah->invflags & ~IPT_AH_INV_MASK)
printf("Unknown invflags: 0x%X ",
ah->invflags & ~IPT_AH_INV_MASK);
}
/* Saves the union ipt_matchinfo in parsable form to stdout. */
static void save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
{
const struct ipt_ah *ahinfo = (struct ipt_ah *)match->data;
if (ahinfo->spis[0] != 0
&& ahinfo->spis[1] != 0xFFFFFFFF) {
if (ahinfo->invflags & IPT_AH_INV_SPI)
printf("! ");
if (ahinfo->spis[0]
!= ahinfo->spis[1])
printf("--spi %u-%u ",
ahinfo->spis[0],
ahinfo->spis[1]);
else
printf("--spi %u ",
ahinfo->spis[0]);
}
}
struct iptables_match ah
= { NULL,
"ah",
NETFILTER_VERSION,
IPT_ALIGN(sizeof(struct ipt_ah)),
IPT_ALIGN(sizeof(struct ipt_ah)),
&help,
&init,
&parse,
&final_check,
&print,
&save,
opts
};
void
_init(void)
{
register_match(&ah);
}
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