| /* Shared library add-on to iptables to add TTL matching support |
| * (C) 2000 by Harald Welte <laforge@gnumonks.org> |
| * |
| * This program is released under the terms of GNU GPL */ |
| #include <stdio.h> |
| #include <xtables.h> |
| #include <linux/netfilter_ipv4/ipt_ttl.h> |
| |
| enum { |
| O_TTL_EQ = 0, |
| O_TTL_LT, |
| O_TTL_GT, |
| F_TTL_EQ = 1 << O_TTL_EQ, |
| F_TTL_LT = 1 << O_TTL_LT, |
| F_TTL_GT = 1 << O_TTL_GT, |
| F_ANY = F_TTL_EQ | F_TTL_LT | F_TTL_GT, |
| }; |
| |
| 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 void ttl_parse(struct xt_option_call *cb) |
| { |
| struct ipt_ttl_info *info = cb->data; |
| |
| xtables_option_parse(cb); |
| switch (cb->entry->id) { |
| case O_TTL_EQ: |
| info->mode = cb->invert ? IPT_TTL_NE : IPT_TTL_EQ; |
| break; |
| case O_TTL_LT: |
| info->mode = IPT_TTL_LT; |
| break; |
| case O_TTL_GT: |
| info->mode = IPT_TTL_GT; |
| break; |
| } |
| } |
| |
| static void ttl_check(struct xt_fcheck_call *cb) |
| { |
| if (!(cb->xflags & F_ANY)) |
| 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 int ttl_xlate(struct xt_xlate *xl, |
| const struct xt_xlate_mt_params *params) |
| { |
| const struct ipt_ttl_info *info = |
| (struct ipt_ttl_info *) params->match->data; |
| |
| switch (info->mode) { |
| case IPT_TTL_EQ: |
| xt_xlate_add(xl, "ip ttl"); |
| break; |
| case IPT_TTL_NE: |
| xt_xlate_add(xl, "ip ttl !="); |
| break; |
| case IPT_TTL_LT: |
| xt_xlate_add(xl, "ip ttl lt"); |
| break; |
| case IPT_TTL_GT: |
| xt_xlate_add(xl, "ip ttl gt"); |
| break; |
| default: |
| /* Should not happen. */ |
| break; |
| } |
| |
| xt_xlate_add(xl, " %u", info->ttl); |
| |
| return 1; |
| } |
| |
| #define s struct ipt_ttl_info |
| static const struct xt_option_entry ttl_opts[] = { |
| {.name = "ttl-lt", .id = O_TTL_LT, .excl = F_ANY, .type = XTTYPE_UINT8, |
| .flags = XTOPT_PUT, XTOPT_POINTER(s, ttl)}, |
| {.name = "ttl-gt", .id = O_TTL_GT, .excl = F_ANY, .type = XTTYPE_UINT8, |
| .flags = XTOPT_PUT, XTOPT_POINTER(s, ttl)}, |
| {.name = "ttl-eq", .id = O_TTL_EQ, .excl = F_ANY, .type = XTTYPE_UINT8, |
| .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, ttl)}, |
| {.name = "ttl", .id = O_TTL_EQ, .excl = F_ANY, .type = XTTYPE_UINT8, |
| .flags = XTOPT_PUT, XTOPT_POINTER(s, ttl)}, |
| XTOPT_TABLEEND, |
| }; |
| #undef s |
| |
| 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, |
| .print = ttl_print, |
| .save = ttl_save, |
| .x6_parse = ttl_parse, |
| .x6_fcheck = ttl_check, |
| .x6_options = ttl_opts, |
| .xlate = ttl_xlate, |
| }; |
| |
| |
| void _init(void) |
| { |
| xtables_register_match(&ttl_mt_reg); |
| } |