| #include <stdio.h> |
| #include <string.h> |
| #include <stdlib.h> |
| #include <xtables.h> |
| #include <limits.h> /* INT_MAX in ip_tables.h */ |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <net/netfilter/nf_nat.h> |
| |
| enum { |
| O_TO_PORTS = 0, |
| O_RANDOM, |
| F_TO_PORTS = 1 << O_TO_PORTS, |
| F_RANDOM = 1 << O_RANDOM, |
| }; |
| |
| static void REDIRECT_help(void) |
| { |
| printf( |
| "REDIRECT target options:\n" |
| " --to-ports <port>[-<port>]\n" |
| " Port (range) to map to.\n" |
| " [--random]\n"); |
| } |
| |
| static const struct xt_option_entry REDIRECT_opts[] = { |
| {.name = "to-ports", .id = O_TO_PORTS, .type = XTTYPE_STRING}, |
| {.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE}, |
| XTOPT_TABLEEND, |
| }; |
| |
| static void REDIRECT_init(struct xt_entry_target *t) |
| { |
| struct nf_nat_multi_range *mr = (struct nf_nat_multi_range *)t->data; |
| |
| /* Actually, it's 0, but it's ignored at the moment. */ |
| mr->rangesize = 1; |
| } |
| |
| /* Parses ports */ |
| static void |
| parse_ports(const char *arg, struct nf_nat_multi_range *mr) |
| { |
| char *end = ""; |
| unsigned int port, maxport; |
| |
| mr->range[0].flags |= IP_NAT_RANGE_PROTO_SPECIFIED; |
| |
| if (!xtables_strtoui(arg, &end, &port, 0, UINT16_MAX) && |
| (port = xtables_service_to_port(arg, NULL)) == (unsigned)-1) |
| xtables_param_act(XTF_BAD_VALUE, "REDIRECT", "--to-ports", arg); |
| |
| switch (*end) { |
| case '\0': |
| mr->range[0].min.tcp.port |
| = mr->range[0].max.tcp.port |
| = htons(port); |
| return; |
| case '-': |
| if (!xtables_strtoui(end + 1, NULL, &maxport, 0, UINT16_MAX) && |
| (maxport = xtables_service_to_port(end + 1, NULL)) == (unsigned)-1) |
| break; |
| |
| if (maxport < port) |
| break; |
| |
| mr->range[0].min.tcp.port = htons(port); |
| mr->range[0].max.tcp.port = htons(maxport); |
| return; |
| default: |
| break; |
| } |
| xtables_param_act(XTF_BAD_VALUE, "REDIRECT", "--to-ports", arg); |
| } |
| |
| static void REDIRECT_parse(struct xt_option_call *cb) |
| { |
| const struct ipt_entry *entry = cb->xt_entry; |
| struct nf_nat_multi_range *mr = (void *)(*cb->target)->data; |
| int portok; |
| |
| if (entry->ip.proto == IPPROTO_TCP |
| || entry->ip.proto == IPPROTO_UDP |
| || entry->ip.proto == IPPROTO_SCTP |
| || entry->ip.proto == IPPROTO_DCCP |
| || entry->ip.proto == IPPROTO_ICMP) |
| portok = 1; |
| else |
| portok = 0; |
| |
| xtables_option_parse(cb); |
| switch (cb->entry->id) { |
| case O_TO_PORTS: |
| if (!portok) |
| xtables_error(PARAMETER_PROBLEM, |
| "Need TCP, UDP, SCTP or DCCP with port specification"); |
| parse_ports(cb->arg, mr); |
| if (cb->xflags & F_RANDOM) |
| mr->range[0].flags |= IP_NAT_RANGE_PROTO_RANDOM; |
| break; |
| case O_RANDOM: |
| if (cb->xflags & F_TO_PORTS) |
| mr->range[0].flags |= IP_NAT_RANGE_PROTO_RANDOM; |
| break; |
| } |
| } |
| |
| static void REDIRECT_print(const void *ip, const struct xt_entry_target *target, |
| int numeric) |
| { |
| const struct nf_nat_multi_range *mr = (const void *)target->data; |
| const struct nf_nat_range *r = &mr->range[0]; |
| |
| if (r->flags & IP_NAT_RANGE_PROTO_SPECIFIED) { |
| printf(" redir ports "); |
| printf("%hu", ntohs(r->min.tcp.port)); |
| if (r->max.tcp.port != r->min.tcp.port) |
| printf("-%hu", ntohs(r->max.tcp.port)); |
| if (mr->range[0].flags & IP_NAT_RANGE_PROTO_RANDOM) |
| printf(" random"); |
| } |
| } |
| |
| static void REDIRECT_save(const void *ip, const struct xt_entry_target *target) |
| { |
| const struct nf_nat_multi_range *mr = (const void *)target->data; |
| const struct nf_nat_range *r = &mr->range[0]; |
| |
| if (r->flags & IP_NAT_RANGE_PROTO_SPECIFIED) { |
| printf(" --to-ports "); |
| printf("%hu", ntohs(r->min.tcp.port)); |
| if (r->max.tcp.port != r->min.tcp.port) |
| printf("-%hu", ntohs(r->max.tcp.port)); |
| if (mr->range[0].flags & IP_NAT_RANGE_PROTO_RANDOM) |
| printf(" --random"); |
| } |
| } |
| |
| static struct xtables_target redirect_tg_reg = { |
| .name = "REDIRECT", |
| .version = XTABLES_VERSION, |
| .family = NFPROTO_IPV4, |
| .size = XT_ALIGN(sizeof(struct nf_nat_multi_range)), |
| .userspacesize = XT_ALIGN(sizeof(struct nf_nat_multi_range)), |
| .help = REDIRECT_help, |
| .init = REDIRECT_init, |
| .x6_parse = REDIRECT_parse, |
| .print = REDIRECT_print, |
| .save = REDIRECT_save, |
| .x6_options = REDIRECT_opts, |
| }; |
| |
| void _init(void) |
| { |
| xtables_register_target(&redirect_tg_reg); |
| } |