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