| /* Shared library add-on to iptables to add connection limit support. */ |
| #include <stdio.h> |
| #include <netdb.h> |
| #include <string.h> |
| #include <stdlib.h> |
| #include <stddef.h> |
| #include <getopt.h> |
| #include <ip6tables.h> |
| #include "../include/linux/netfilter/xt_connlimit.h" |
| |
| /* Function which prints out usage message. */ |
| static void connlimit_help(void) |
| { |
| printf( |
| "connlimit v%s options:\n" |
| "[!] --connlimit-above n match if the number of existing " |
| " connections is (not) above n\n" |
| " --connlimit-mask n group hosts using mask\n" |
| "\n", IPTABLES_VERSION); |
| } |
| |
| static const struct option connlimit_opts[] = { |
| {"connlimit-above", 1, NULL, 1}, |
| {"connlimit-mask", 1, NULL, 2}, |
| {NULL}, |
| }; |
| |
| static void connlimit_init(struct ip6t_entry_match *match, unsigned int *nfc) |
| { |
| struct xt_connlimit_info *info = (void *)match->data; |
| info->v6_mask[0] = |
| info->v6_mask[1] = |
| info->v6_mask[2] = |
| info->v6_mask[3] = 0xFFFFFFFF; |
| } |
| |
| static void prefix_to_netmask(u_int32_t *mask, unsigned int prefix_len) |
| { |
| if (prefix_len == 0) { |
| mask[0] = mask[1] = mask[2] = mask[3] = 0; |
| } else if (prefix_len <= 32) { |
| mask[0] <<= 32 - prefix_len; |
| mask[1] = mask[2] = mask[3] = 0; |
| } else if (prefix_len <= 64) { |
| mask[1] <<= 32 - (prefix_len - 32); |
| mask[2] = mask[3] = 0; |
| } else if (prefix_len <= 96) { |
| mask[2] <<= 32 - (prefix_len - 64); |
| mask[3] = 0; |
| } else if (prefix_len <= 128) { |
| mask[3] <<= 32 - (prefix_len - 96); |
| } |
| mask[0] = htonl(mask[0]); |
| mask[1] = htonl(mask[1]); |
| mask[2] = htonl(mask[2]); |
| mask[3] = htonl(mask[3]); |
| } |
| |
| static int connlimit_parse(int c, char **argv, int invert, unsigned int *flags, |
| const struct ip6t_entry *entry, |
| unsigned int *nfcache, |
| struct ip6t_entry_match **match) |
| { |
| struct xt_connlimit_info *info = (void *)(*match)->data; |
| char *err; |
| int i; |
| |
| if (*flags & c) |
| exit_error(PARAMETER_PROBLEM, |
| "--connlimit-above and/or --connlimit-mask may " |
| "only be given once"); |
| |
| switch (c) { |
| case 1: |
| check_inverse(optarg, &invert, &optind, 0); |
| info->limit = strtoul(argv[optind-1], NULL, 0); |
| info->inverse = invert; |
| break; |
| case 2: |
| i = strtoul(argv[optind-1], &err, 0); |
| if (i > 128 || *err != '\0') |
| exit_error(PARAMETER_PROBLEM, |
| "--connlimit-mask must be between 0 and 128"); |
| prefix_to_netmask(info->v6_mask, i); |
| break; |
| default: |
| return 0; |
| } |
| |
| *flags |= c; |
| return 1; |
| } |
| |
| /* Final check */ |
| static void connlimit_check(unsigned int flags) |
| { |
| if (!(flags & 1)) |
| exit_error(PARAMETER_PROBLEM, |
| "You must specify \"--connlimit-above\""); |
| } |
| |
| static unsigned int count_bits(const u_int32_t *mask) |
| { |
| unsigned int bits = 0, i; |
| u_int32_t tmp[4]; |
| |
| for (i = 0; i < 4; ++i) |
| for (tmp[i] = ~ntohl(mask[i]); tmp[i] != 0; tmp[i] >>= 1) |
| ++bits; |
| return 128 - bits; |
| } |
| |
| /* Prints out the matchinfo. */ |
| static void connlimit_print(const struct ip6t_ip6 *ip, |
| const struct ip6t_entry_match *match, int numeric) |
| { |
| const struct xt_connlimit_info *info = (const void *)match->data; |
| |
| printf("#conn/%u %s %u ", count_bits(info->v6_mask), |
| info->inverse ? "<" : ">", info->limit); |
| } |
| |
| /* Saves the matchinfo in parsable form to stdout. */ |
| static void connlimit_save(const struct ip6t_ip6 *ip, |
| const struct ip6t_entry_match *match) |
| { |
| const struct xt_connlimit_info *info = (const void *)match->data; |
| |
| printf("%s--connlimit-above %u --connlimit-mask %u ", |
| info->inverse ? "! " : "", info->limit, |
| count_bits(info->v6_mask)); |
| } |
| |
| static struct ip6tables_match connlimit_reg = { |
| .name = "connlimit", |
| .version = IPTABLES_VERSION, |
| .size = IP6T_ALIGN(sizeof(struct xt_connlimit_info)), |
| .userspacesize = offsetof(struct xt_connlimit_info, data), |
| .help = connlimit_help, |
| .init = connlimit_init, |
| .parse = connlimit_parse, |
| .final_check = connlimit_check, |
| .print = connlimit_print, |
| .save = connlimit_save, |
| .extra_opts = connlimit_opts, |
| }; |
| |
| void _init(void) |
| { |
| register_match6(&connlimit_reg); |
| } |