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/* Shared library add-on to ip6tables to add Dst header support. */
#include <stdbool.h>
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <errno.h>
#include <xtables.h>
#include <linux/netfilter_ipv6/ip6t_opts.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
static void dst_help(void)
{
printf(
"dst match options:\n"
"[!] --dst-len length total length of this header\n"
" --dst-opts TYPE[:LEN][,TYPE[:LEN]...]\n"
" Options and its length (list, max: %d)\n",
IP6T_OPTS_OPTSNR);
}
static const struct option dst_opts[] = {
{.name = "dst-len", .has_arg = true, .val = '1'},
{.name = "dst-opts", .has_arg = true, .val = '2'},
XT_GETOPT_TABLEEND,
};
static uint32_t
parse_opts_num(const char *idstr, const char *typestr)
{
unsigned long int id;
char* ep;
id = strtoul(idstr, &ep, 0);
if ( idstr == ep ) {
xtables_error(PARAMETER_PROBLEM,
"dst: no valid digits in %s `%s'", typestr, idstr);
}
if ( id == ULONG_MAX && errno == ERANGE ) {
xtables_error(PARAMETER_PROBLEM,
"%s `%s' specified too big: would overflow",
typestr, idstr);
}
if ( *idstr != '\0' && *ep != '\0' ) {
xtables_error(PARAMETER_PROBLEM,
"dst: error parsing %s `%s'", typestr, idstr);
}
return id;
}
static int
parse_options(const char *optsstr, uint16_t *opts)
{
char *buffer, *cp, *next, *range;
unsigned int i;
buffer = strdup(optsstr);
if (!buffer)
xtables_error(OTHER_PROBLEM, "strdup failed");
for (cp = buffer, i = 0; cp && i < IP6T_OPTS_OPTSNR; cp = next, i++)
{
next = strchr(cp, ',');
if (next)
*next++='\0';
range = strchr(cp, ':');
if (range) {
if (i == IP6T_OPTS_OPTSNR-1)
xtables_error(PARAMETER_PROBLEM,
"too many ports specified");
*range++ = '\0';
}
opts[i] = (parse_opts_num(cp, "opt") & 0xFF) << 8;
if (range) {
if (opts[i] == 0)
xtables_error(PARAMETER_PROBLEM,
"PAD0 hasn't got length");
opts[i] |= parse_opts_num(range, "length") & 0xFF;
} else
opts[i] |= (0x00FF);
#ifdef DEBUG
printf("opts str: %s %s\n", cp, range);
printf("opts opt: %04X\n", opts[i]);
#endif
}
if (cp)
xtables_error(PARAMETER_PROBLEM, "too many addresses specified");
free(buffer);
#ifdef DEBUG
printf("addr nr: %d\n", i);
#endif
return i;
}
static int dst_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_match **match)
{
struct ip6t_opts *optinfo = (struct ip6t_opts *)(*match)->data;
switch (c) {
case '1':
if (*flags & IP6T_OPTS_LEN)
xtables_error(PARAMETER_PROBLEM,
"Only one `--dst-len' allowed");
xtables_check_inverse(optarg, &invert, &optind, 0, argv);
optinfo->hdrlen = parse_opts_num(optarg, "length");
if (invert)
optinfo->invflags |= IP6T_OPTS_INV_LEN;
optinfo->flags |= IP6T_OPTS_LEN;
*flags |= IP6T_OPTS_LEN;
break;
case '2':
if (*flags & IP6T_OPTS_OPTS)
xtables_error(PARAMETER_PROBLEM,
"Only one `--dst-opts' allowed");
xtables_check_inverse(optarg, &invert, &optind, 0, argv);
if (invert)
xtables_error(PARAMETER_PROBLEM,
" '!' not allowed with `--dst-opts'");
optinfo->optsnr = parse_options(optarg, optinfo->opts);
optinfo->flags |= IP6T_OPTS_OPTS;
*flags |= IP6T_OPTS_OPTS;
break;
}
return 1;
}
static void
print_options(unsigned int optsnr, uint16_t *optsp)
{
unsigned int i;
printf(" ");
for(i = 0; i < optsnr; i++) {
printf("%d", (optsp[i] & 0xFF00) >> 8);
if ((optsp[i] & 0x00FF) != 0x00FF)
printf(":%d", (optsp[i] & 0x00FF));
printf("%c", (i != optsnr - 1) ? ',' : ' ');
}
}
static void dst_print(const void *ip, const struct xt_entry_match *match,
int numeric)
{
const struct ip6t_opts *optinfo = (struct ip6t_opts *)match->data;
printf(" dst");
if (optinfo->flags & IP6T_OPTS_LEN)
printf(" length:%s%u",
optinfo->invflags & IP6T_OPTS_INV_LEN ? "!" : "",
optinfo->hdrlen);
if (optinfo->flags & IP6T_OPTS_OPTS)
printf(" opts");
print_options(optinfo->optsnr, (uint16_t *)optinfo->opts);
if (optinfo->invflags & ~IP6T_OPTS_INV_MASK)
printf(" Unknown invflags: 0x%X",
optinfo->invflags & ~IP6T_OPTS_INV_MASK);
}
static void dst_save(const void *ip, const struct xt_entry_match *match)
{
const struct ip6t_opts *optinfo = (struct ip6t_opts *)match->data;
if (optinfo->flags & IP6T_OPTS_LEN) {
printf("%s --dst-len %u",
(optinfo->invflags & IP6T_OPTS_INV_LEN) ? " !" : "",
optinfo->hdrlen);
}
if (optinfo->flags & IP6T_OPTS_OPTS)
printf(" --dst-opts");
print_options(optinfo->optsnr, (uint16_t *)optinfo->opts);
}
static struct xtables_match dst_mt6_reg = {
.name = "dst",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV6,
.size = XT_ALIGN(sizeof(struct ip6t_opts)),
.userspacesize = XT_ALIGN(sizeof(struct ip6t_opts)),
.help = dst_help,
.parse = dst_parse,
.print = dst_print,
.save = dst_save,
.extra_opts = dst_opts,
};
void
_init(void)
{
xtables_register_match(&dst_mt6_reg);
}
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