#include <stdio.h>
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#include <xtables.h>
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#include <linux/netfilter/xt_tcpmss.h>
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enum {
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O_TCPMSS = 0,
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};
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static void tcpmss_help(void)
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{
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printf(
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"tcpmss match options:\n"
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"[!] --mss value[:value] Match TCP MSS range.\n"
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" (only valid for TCP SYN or SYN/ACK packets)\n");
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}
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static const struct xt_option_entry tcpmss_opts[] = {
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{.name = "mss", .id = O_TCPMSS, .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 tcpmss_parse(struct xt_option_call *cb)
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{
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struct xt_tcpmss_match_info *mssinfo = cb->data;
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xtables_option_parse(cb);
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mssinfo->mss_min = cb->val.u16_range[0];
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mssinfo->mss_max = mssinfo->mss_min;
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if (cb->nvals == 2)
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mssinfo->mss_max = cb->val.u16_range[1];
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if (cb->invert)
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mssinfo->invert = 1;
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}
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static void
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tcpmss_print(const void *ip, const struct xt_entry_match *match, int numeric)
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{
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const struct xt_tcpmss_match_info *info = (void *)match->data;
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printf(" tcpmss match %s", info->invert ? "!" : "");
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if (info->mss_min == info->mss_max)
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printf("%u", info->mss_min);
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else
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printf("%u:%u", info->mss_min, info->mss_max);
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}
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static void tcpmss_save(const void *ip, const struct xt_entry_match *match)
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{
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const struct xt_tcpmss_match_info *info = (void *)match->data;
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printf("%s --mss ", info->invert ? " !" : "");
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if (info->mss_min == info->mss_max)
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printf("%u", info->mss_min);
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else
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printf("%u:%u", info->mss_min, info->mss_max);
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}
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static struct xtables_match tcpmss_match = {
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.family = NFPROTO_UNSPEC,
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.name = "tcpmss",
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.version = XTABLES_VERSION,
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.size = XT_ALIGN(sizeof(struct xt_tcpmss_match_info)),
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.userspacesize = XT_ALIGN(sizeof(struct xt_tcpmss_match_info)),
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.help = tcpmss_help,
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.print = tcpmss_print,
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.save = tcpmss_save,
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.x6_parse = tcpmss_parse,
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.x6_options = tcpmss_opts,
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};
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void _init(void)
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{
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xtables_register_match(&tcpmss_match);
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}
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