diff options
Diffstat (limited to 'extensions/libipt_ttl.c')
| -rw-r--r-- | extensions/libipt_ttl.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/extensions/libipt_ttl.c b/extensions/libipt_ttl.c new file mode 100644 index 0000000..e2fbcd5 --- /dev/null +++ b/extensions/libipt_ttl.c @@ -0,0 +1,167 @@ +/* Shared library add-on to iptables to add TTL matching support + * (C) 2000 by Harald Welte <laforge@gnumonks.org> + * + * $Id$ + * + * This program is released under the terms of GNU GPL */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <getopt.h> +#include <xtables.h> + +#include <linux/netfilter_ipv4/ipt_ttl.h> + +static void ttl_help(void) +{ + printf( +"ttl match options:\n" +" --ttl-eq value Match time to live value\n" +" --ttl-lt value Match TTL < value\n" +" --ttl-gt value Match TTL > value\n"); +} + +static int ttl_parse(int c, char **argv, int invert, unsigned int *flags, + const void *entry, struct xt_entry_match **match) +{ + struct ipt_ttl_info *info = (struct ipt_ttl_info *) (*match)->data; + unsigned int value; + + xtables_check_inverse(optarg, &invert, &optind, 0, argv); + + switch (c) { + case '2': + if (!xtables_strtoui(optarg, NULL, &value, 0, UINT8_MAX)) + xtables_error(PARAMETER_PROBLEM, + "ttl: Expected value between 0 and 255"); + + if (invert) + info->mode = IPT_TTL_NE; + else + info->mode = IPT_TTL_EQ; + + /* is 0 allowed? */ + info->ttl = value; + break; + case '3': + if (!xtables_strtoui(optarg, NULL, &value, 0, UINT8_MAX)) + xtables_error(PARAMETER_PROBLEM, + "ttl: Expected value between 0 and 255"); + + if (invert) + xtables_error(PARAMETER_PROBLEM, + "ttl: unexpected `!'"); + + info->mode = IPT_TTL_LT; + info->ttl = value; + break; + case '4': + if (!xtables_strtoui(optarg, NULL, &value, 0, UINT8_MAX)) + xtables_error(PARAMETER_PROBLEM, + "ttl: Expected value between 0 and 255"); + + if (invert) + xtables_error(PARAMETER_PROBLEM, + "ttl: unexpected `!'"); + + info->mode = IPT_TTL_GT; + info->ttl = value; + break; + default: + return 0; + + } + + if (*flags) + xtables_error(PARAMETER_PROBLEM, + "Can't specify TTL option twice"); + *flags = 1; + + return 1; +} + +static void ttl_check(unsigned int flags) +{ + if (!flags) + xtables_error(PARAMETER_PROBLEM, + "TTL match: You must specify one of " + "`--ttl-eq', `--ttl-lt', `--ttl-gt"); +} + +static void ttl_print(const void *ip, const struct xt_entry_match *match, + int numeric) +{ + const struct ipt_ttl_info *info = + (struct ipt_ttl_info *) match->data; + + printf("TTL match "); + switch (info->mode) { + case IPT_TTL_EQ: + printf("TTL == "); + break; + case IPT_TTL_NE: + printf("TTL != "); + break; + case IPT_TTL_LT: + printf("TTL < "); + break; + case IPT_TTL_GT: + printf("TTL > "); + break; + } + printf("%u ", info->ttl); +} + +static void ttl_save(const void *ip, const struct xt_entry_match *match) +{ + const struct ipt_ttl_info *info = + (struct ipt_ttl_info *) match->data; + + switch (info->mode) { + case IPT_TTL_EQ: + printf("--ttl-eq "); + break; + case IPT_TTL_NE: + printf("! --ttl-eq "); + break; + case IPT_TTL_LT: + printf("--ttl-lt "); + break; + case IPT_TTL_GT: + printf("--ttl-gt "); + break; + default: + /* error */ + break; + } + printf("%u ", info->ttl); +} + +static const struct option ttl_opts[] = { + { "ttl", 1, NULL, '2' }, + { "ttl-eq", 1, NULL, '2'}, + { "ttl-lt", 1, NULL, '3'}, + { "ttl-gt", 1, NULL, '4'}, + { .name = NULL } +}; + +static struct xtables_match ttl_mt_reg = { + .name = "ttl", + .version = XTABLES_VERSION, + .family = NFPROTO_IPV4, + .size = XT_ALIGN(sizeof(struct ipt_ttl_info)), + .userspacesize = XT_ALIGN(sizeof(struct ipt_ttl_info)), + .help = ttl_help, + .parse = ttl_parse, + .final_check = ttl_check, + .print = ttl_print, + .save = ttl_save, + .extra_opts = ttl_opts, +}; + + +void _init(void) +{ + xtables_register_match(&ttl_mt_reg); +} |