| #include <stdio.h> |
| #include <netdb.h> |
| #include <string.h> |
| #include <stdlib.h> |
| #include <getopt.h> |
| #include <xtables.h> |
| #include <limits.h> /* INT_MAX in ip_tables.h */ |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <linux/netfilter/nf_nat.h> |
| |
| enum { |
| O_TO_PORTS = 0, |
| O_RANDOM, |
| O_RANDOM_FULLY, |
| }; |
| |
| static void MASQUERADE_help(void) |
| { |
| printf( |
| "MASQUERADE target options:\n" |
| " --to-ports <port>[-<port>]\n" |
| " Port (range) to map to.\n" |
| " --random\n" |
| " Randomize source port.\n" |
| " --random-fully\n" |
| " Fully randomize source port.\n"); |
| } |
| |
| static const struct xt_option_entry MASQUERADE_opts[] = { |
| {.name = "to-ports", .id = O_TO_PORTS, .type = XTTYPE_STRING}, |
| {.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE}, |
| {.name = "random-fully", .id = O_RANDOM_FULLY, .type = XTTYPE_NONE}, |
| XTOPT_TABLEEND, |
| }; |
| |
| static void MASQUERADE_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; |
| } |
| |
| /* Parses ports */ |
| static void |
| parse_ports(const char *arg, struct nf_nat_ipv4_multi_range_compat *mr) |
| { |
| char *end; |
| unsigned int port, maxport; |
| |
| mr->range[0].flags |= NF_NAT_RANGE_PROTO_SPECIFIED; |
| |
| if (!xtables_strtoui(arg, &end, &port, 0, UINT16_MAX)) |
| xtables_param_act(XTF_BAD_VALUE, "MASQUERADE", "--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)) |
| 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, "MASQUERADE", "--to-ports", arg); |
| } |
| |
| static void MASQUERADE_parse(struct xt_option_call *cb) |
| { |
| const struct ipt_entry *entry = cb->xt_entry; |
| int portok; |
| struct nf_nat_ipv4_multi_range_compat *mr = cb->data; |
| |
| 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); |
| break; |
| case O_RANDOM: |
| mr->range[0].flags |= NF_NAT_RANGE_PROTO_RANDOM; |
| break; |
| case O_RANDOM_FULLY: |
| mr->range[0].flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY; |
| break; |
| } |
| } |
| |
| static void |
| MASQUERADE_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]; |
| |
| if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) { |
| printf(" masq 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 (r->flags & NF_NAT_RANGE_PROTO_RANDOM) |
| printf(" random"); |
| |
| if (r->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) |
| printf(" random-fully"); |
| } |
| |
| static void |
| MASQUERADE_save(const void *ip, const struct xt_entry_target *target) |
| { |
| const struct nf_nat_ipv4_multi_range_compat *mr = (const void *)target->data; |
| const struct nf_nat_ipv4_range *r = &mr->range[0]; |
| |
| if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) { |
| printf(" --to-ports %hu", ntohs(r->min.tcp.port)); |
| if (r->max.tcp.port != r->min.tcp.port) |
| printf("-%hu", ntohs(r->max.tcp.port)); |
| } |
| |
| if (r->flags & NF_NAT_RANGE_PROTO_RANDOM) |
| printf(" --random"); |
| |
| if (r->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) |
| printf(" --random-fully"); |
| } |
| |
| static int MASQUERADE_xlate(struct xt_xlate *xl, |
| const struct xt_xlate_tg_params *params) |
| { |
| const struct nf_nat_ipv4_multi_range_compat *mr = |
| (const void *)params->target->data; |
| const struct nf_nat_ipv4_range *r = &mr->range[0]; |
| |
| xt_xlate_add(xl, "masquerade"); |
| |
| if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) { |
| xt_xlate_add(xl, " to :%hu", ntohs(r->min.tcp.port)); |
| if (r->max.tcp.port != r->min.tcp.port) |
| xt_xlate_add(xl, "-%hu", ntohs(r->max.tcp.port)); |
| } |
| |
| xt_xlate_add(xl, " "); |
| if (r->flags & NF_NAT_RANGE_PROTO_RANDOM) |
| xt_xlate_add(xl, "random "); |
| |
| return 1; |
| } |
| |
| static struct xtables_target masquerade_tg_reg = { |
| .name = "MASQUERADE", |
| .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 = MASQUERADE_help, |
| .init = MASQUERADE_init, |
| .x6_parse = MASQUERADE_parse, |
| .print = MASQUERADE_print, |
| .save = MASQUERADE_save, |
| .x6_options = MASQUERADE_opts, |
| .xlate = MASQUERADE_xlate, |
| }; |
| |
| void _init(void) |
| { |
| xtables_register_target(&masquerade_tg_reg); |
| } |