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/*
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* "ts3init_get_cookie and ts3init_get_puzzle" match extension for iptables
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* Niels Werensteijn <niels werensteijn [at] teamspeak com>, 2016-10-03
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License; either version 2
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* or 3 of the License, as published by the Free Software Foundation.
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*/
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <getopt.h>
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#include <xtables.h>
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#include "ts3init_match.h"
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#define param_act(t, s, f) xtables_param_act((t), "ts3init_get_puzzle", (s), (f))
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#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
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static bool hex2int_seed(const char *src, __u8* dst)
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{
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for (int i = 0; i < 60; ++i)
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{
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int v = 0;
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for (int j = 0; j < 2; ++j)
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{
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uint8_t byte = *src++;
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if (byte >= '0' && byte <= '9') byte = byte - '0';
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else if (byte >= 'a' && byte <='f') byte = byte - 'a' + 10;
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else if (byte >= 'A' && byte <='F') byte = byte - 'A' + 10;
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else return false;
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v = (v << 4) | byte;
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}
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*dst++ = v;
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}
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return true;
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}
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static void ts3init_get_puzzle_help(void)
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{
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printf(
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"ts3init_get_puzzle match options:\n"
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" --min-client n The sending client needs to be at least version n.\n"
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" --check-cookie seed Check the cookie. Assume it was generated with seed.\n"
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" seed is a 60 byte random number in lowecase hex. A source\n"
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" could be /dev/random.\n"
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);
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}
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static const struct option ts3init_get_puzzle_opts[] = {
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{.name = "min-client", .has_arg = true, .val = '1'},
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{.name = "check-cookie", .has_arg = true, .val = '2'},
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{NULL},
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};
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static int ts3init_get_puzzle_parse(int c, char **argv, int invert, unsigned int *flags,
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const void *entry, struct xt_entry_match **match)
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{
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struct xt_ts3init_get_puzzle_mtinfo *info = (void *)(*match)->data;
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int client_version;
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switch (c) {
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case '1':
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param_act(XTF_ONLY_ONCE, "--min-client", info->common_options & CHK_COMMON_CLIENT_VERSION);
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param_act(XTF_NO_INVERT, "--min-client", invert);
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client_version = atoi(optarg);
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if (client_version <= 0)
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xtables_error(PARAMETER_PROBLEM,
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"ts3init_get_cookie: invalid min-client version");
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info->common_options |= CHK_COMMON_CLIENT_VERSION;
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info->min_client_version = client_version - CLIENT_VERSION_OFFSET;
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return true;
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case '2':
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param_act(XTF_ONLY_ONCE, "--check-cookie", info->specific_options & CHK_GET_PUZZLE_CHECK_COOKIE);
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param_act(XTF_NO_INVERT, "--check-cookie", invert);
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if (strlen(optarg) != 120)
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xtables_error(PARAMETER_PROBLEM,
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"ts3init_get_puzzle: invalid cookie-seed length");
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if (!hex2int_seed(optarg, info->cookie_seed))
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xtables_error(PARAMETER_PROBLEM,
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"ts3init_get_puzzle: invalid cookie-seed. (not lowercase hex)");
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info->specific_options |= CHK_GET_PUZZLE_CHECK_COOKIE;
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return true;
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default:
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return false;
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}
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}
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static void ts3init_get_puzzle_save(const void *ip, const struct xt_entry_match *match)
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{
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const struct xt_ts3init_get_puzzle_mtinfo *info = (const void *)match->data;
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if (info->common_options & CHK_COMMON_CLIENT_VERSION)
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{
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printf("--min-client %u ", info->min_client_version + CLIENT_VERSION_OFFSET);
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}
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if (info->specific_options & CHK_GET_PUZZLE_CHECK_COOKIE)
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{
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printf("--check-cookie ");
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for (int i = 0; i < 60; i++)
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{
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printf("%02X", info->cookie_seed[i]);
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}
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printf(" ");
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}
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}
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static void ts3init_get_puzzle_print(const void *ip, const struct xt_entry_match *match,
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int numeric)
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{
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printf(" -m ts3init_get_puzzle ");
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ts3init_get_puzzle_save(ip, match);
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}
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/* register and init */
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static struct xtables_match ts3init_mt_reg[] =
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{
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{
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.name = "ts3init_get_puzzle",
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.revision = 0,
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.family = NFPROTO_IPV4,
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.version = XTABLES_VERSION,
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.size = XT_ALIGN(sizeof(struct xt_ts3init_get_puzzle_mtinfo)),
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.userspacesize = XT_ALIGN(sizeof(struct xt_ts3init_get_puzzle_mtinfo)),
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.help = ts3init_get_puzzle_help,
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.parse = ts3init_get_puzzle_parse,
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.print = ts3init_get_puzzle_print,
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.save = ts3init_get_puzzle_save,
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.extra_opts = ts3init_get_puzzle_opts,
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},
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{
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.name = "ts3init_get_puzzle",
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.revision = 0,
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.family = NFPROTO_IPV6,
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.version = XTABLES_VERSION,
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.size = XT_ALIGN(sizeof(struct xt_ts3init_get_puzzle_mtinfo)),
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.userspacesize = XT_ALIGN(sizeof(struct xt_ts3init_get_puzzle_mtinfo)),
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.help = ts3init_get_puzzle_help,
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.parse = ts3init_get_puzzle_parse,
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.print = ts3init_get_puzzle_print,
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.save = ts3init_get_puzzle_save,
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.extra_opts = ts3init_get_puzzle_opts,
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}
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};
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static __attribute__((constructor)) void ts3init_mt_ldr(void)
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{
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xtables_register_matches(ts3init_mt_reg, ARRAY_SIZE(ts3init_mt_reg));
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}
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