| /* Shared library add-on to iptables to add static NAT support. |
| Author: Svenning Soerensen <svenning@post5.tele.dk> |
| */ |
| #include <stdio.h> |
| #include <netdb.h> |
| #include <string.h> |
| #include <stdlib.h> |
| #include <getopt.h> |
| #include <xtables.h> |
| #include <linux/netfilter/nf_nat.h> |
| |
| #define MODULENAME "NETMAP" |
| |
| enum { |
| O_TO = 0, |
| }; |
| |
| static const struct xt_option_entry NETMAP_opts[] = { |
| {.name = "to", .id = O_TO, .type = XTTYPE_HOSTMASK, |
| .flags = XTOPT_MAND}, |
| XTOPT_TABLEEND, |
| }; |
| |
| static void NETMAP_help(void) |
| { |
| printf(MODULENAME" target options:\n" |
| " --%s address[/mask]\n" |
| " Network address to map to.\n\n", |
| NETMAP_opts[0].name); |
| } |
| |
| static int |
| netmask2bits(uint32_t netmask) |
| { |
| uint32_t bm; |
| int bits; |
| |
| netmask = ntohl(netmask); |
| for (bits = 0, bm = 0x80000000; netmask & bm; netmask <<= 1) |
| bits++; |
| if (netmask) |
| return -1; /* holes in netmask */ |
| return bits; |
| } |
| |
| static void NETMAP_init(struct xt_entry_target *t) |
| { |
| struct nf_nat_ipv4_multi_range_compat *mr = (struct nf_nat_ipv4_multi_range_compat *)t->data; |
| |
| /* Actually, it's 0, but it's ignored at the moment. */ |
| mr->rangesize = 1; |
| } |
| |
| static void NETMAP_parse(struct xt_option_call *cb) |
| { |
| struct nf_nat_ipv4_multi_range_compat *mr = cb->data; |
| struct nf_nat_ipv4_range *range = &mr->range[0]; |
| |
| xtables_option_parse(cb); |
| range->flags |= NF_NAT_RANGE_MAP_IPS; |
| range->min_ip = cb->val.haddr.ip & cb->val.hmask.ip; |
| range->max_ip = range->min_ip | ~cb->val.hmask.ip; |
| } |
| |
| static void __NETMAP_print(const void *ip, const struct xt_entry_target *target, |
| int numeric) |
| { |
| const struct nf_nat_ipv4_multi_range_compat *mr = (const void *)target->data; |
| const struct nf_nat_ipv4_range *r = &mr->range[0]; |
| struct in_addr a; |
| int bits; |
| |
| a.s_addr = r->min_ip; |
| printf("%s", xtables_ipaddr_to_numeric(&a)); |
| a.s_addr = ~(r->min_ip ^ r->max_ip); |
| bits = netmask2bits(a.s_addr); |
| if (bits < 0) |
| printf("/%s", xtables_ipaddr_to_numeric(&a)); |
| else |
| printf("/%d", bits); |
| } |
| |
| static void NETMAP_print(const void *ip, const struct xt_entry_target *target, |
| int numeric) |
| { |
| printf(" to:"); |
| __NETMAP_print(ip, target, numeric); |
| } |
| |
| static void NETMAP_save(const void *ip, const struct xt_entry_target *target) |
| { |
| printf(" --%s ", NETMAP_opts[0].name); |
| __NETMAP_print(ip, target, 0); |
| } |
| |
| static struct xtables_target netmap_tg_reg = { |
| .name = MODULENAME, |
| .version = XTABLES_VERSION, |
| .family = NFPROTO_IPV4, |
| .size = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)), |
| .userspacesize = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)), |
| .help = NETMAP_help, |
| .init = NETMAP_init, |
| .x6_parse = NETMAP_parse, |
| .print = NETMAP_print, |
| .save = NETMAP_save, |
| .x6_options = NETMAP_opts, |
| }; |
| |
| void _init(void) |
| { |
| xtables_register_target(&netmap_tg_reg); |
| } |