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92 lines
2.1 KiB
92 lines
2.1 KiB
#include <stdio.h>
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#include <xtables.h>
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#include <linux/netfilter/xt_length.h>
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enum {
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O_LENGTH = 0,
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};
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static void length_help(void)
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{
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printf(
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"length match options:\n"
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"[!] --length length[:length] Match packet length against value or range\n"
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" of values (inclusive)\n");
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}
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static const struct xt_option_entry length_opts[] = {
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{.name = "length", .id = O_LENGTH, .type = XTTYPE_UINT16RC,
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.flags = XTOPT_MAND | XTOPT_INVERT},
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XTOPT_TABLEEND,
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};
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static void length_parse(struct xt_option_call *cb)
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{
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struct xt_length_info *info = cb->data;
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xtables_option_parse(cb);
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info->min = cb->val.u16_range[0];
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info->max = cb->val.u16_range[0];
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if (cb->nvals >= 2)
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info->max = cb->val.u16_range[1];
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if (cb->invert)
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info->invert = 1;
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}
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static void
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length_print(const void *ip, const struct xt_entry_match *match, int numeric)
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{
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const struct xt_length_info *info = (void *)match->data;
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printf(" length %s", info->invert ? "!" : "");
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if (info->min == info->max)
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printf("%u", info->min);
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else
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printf("%u:%u", info->min, info->max);
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}
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static void length_save(const void *ip, const struct xt_entry_match *match)
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{
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const struct xt_length_info *info = (void *)match->data;
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printf("%s --length ", info->invert ? " !" : "");
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if (info->min == info->max)
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printf("%u", info->min);
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else
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printf("%u:%u", info->min, info->max);
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}
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static int length_xlate(struct xt_xlate *xl,
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const struct xt_xlate_mt_params *params)
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{
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const struct xt_length_info *info = (void *)params->match->data;
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xt_xlate_add(xl, "meta length %s", info->invert ? "!= " : "");
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if (info->min == info->max)
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xt_xlate_add(xl, "%u", info->min);
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else
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xt_xlate_add(xl, "%u-%u", info->min, info->max);
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return 1;
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}
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static struct xtables_match length_match = {
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.family = NFPROTO_UNSPEC,
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.name = "length",
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.version = XTABLES_VERSION,
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.size = XT_ALIGN(sizeof(struct xt_length_info)),
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.userspacesize = XT_ALIGN(sizeof(struct xt_length_info)),
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.help = length_help,
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.print = length_print,
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.save = length_save,
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.x6_parse = length_parse,
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.x6_options = length_opts,
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.xlate = length_xlate,
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};
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void _init(void)
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{
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xtables_register_match(&length_match);
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}
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