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/*
* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
*
* Based on Rusty Russell's IPv4 SNAT target. Development of IPv6 NAT
* funded by Astaro.
*/
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <xtables.h>
#include <iptables.h>
#include <limits.h> /* INT_MAX in ip_tables.h */
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter/nf_nat.h>
enum {
O_TO_SRC = 0,
O_RANDOM,
O_RANDOM_FULLY,
O_PERSISTENT,
O_X_TO_SRC,
F_TO_SRC = 1 << O_TO_SRC,
F_RANDOM = 1 << O_RANDOM,
F_RANDOM_FULLY = 1 << O_RANDOM_FULLY,
F_X_TO_SRC = 1 << O_X_TO_SRC,
};
static void SNAT_help(void)
{
printf(
"SNAT target options:\n"
" --to-source [<ipaddr>[-<ipaddr>]][:port[-port]]\n"
" Address to map source to.\n"
"[--random] [--random-fully] [--persistent]\n");
}
static const struct xt_option_entry SNAT_opts[] = {
{.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING,
.flags = XTOPT_MAND | XTOPT_MULTI},
{.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE},
{.name = "random-fully", .id = O_RANDOM_FULLY, .type = XTTYPE_NONE},
{.name = "persistent", .id = O_PERSISTENT, .type = XTTYPE_NONE},
XTOPT_TABLEEND,
};
/* Ranges expected in network order. */
static void
parse_to(const char *orig_arg, int portok, struct nf_nat_range *range)
{
char *arg, *start, *end = NULL, *colon = NULL, *dash, *error;
const struct in6_addr *ip;
arg = strdup(orig_arg);
if (arg == NULL)
xtables_error(RESOURCE_PROBLEM, "strdup");
start = strchr(arg, '[');
if (start == NULL) {
start = arg;
/* Lets assume one colon is port information. Otherwise its an IPv6 address */
colon = strchr(arg, ':');
if (colon && strchr(colon+1, ':'))
colon = NULL;
}
else {
start++;
end = strchr(start, ']');
if (end == NULL)
xtables_error(PARAMETER_PROBLEM,
"Invalid address format");
*end = '\0';
colon = strchr(end + 1, ':');
}
if (colon) {
int port;
if (!portok)
xtables_error(PARAMETER_PROBLEM,
"Need TCP, UDP, SCTP or DCCP with port specification");
range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
port = atoi(colon+1);
if (port <= 0 || port > 65535)
xtables_error(PARAMETER_PROBLEM,
"Port `%s' not valid\n", colon+1);
error = strchr(colon+1, ':');
if (error)
xtables_error(PARAMETER_PROBLEM,
"Invalid port:port syntax - use dash\n");
dash = strchr(colon, '-');
if (!dash) {
range->min_proto.tcp.port
= range->max_proto.tcp.port
= htons(port);
} else {
int maxport;
maxport = atoi(dash + 1);
if (maxport <= 0 || maxport > 65535)
xtables_error(PARAMETER_PROBLEM,
"Port `%s' not valid\n", dash+1);
if (maxport < port)
/* People are stupid. */
xtables_error(PARAMETER_PROBLEM,
"Port range `%s' funky\n", colon+1);
range->min_proto.tcp.port = htons(port);
range->max_proto.tcp.port = htons(maxport);
}
/* Starts with colon or [] colon? No IP info...*/
if (colon == arg || colon == arg+2) {
free(arg);
return;
}
*colon = '\0';
}
range->flags |= NF_NAT_RANGE_MAP_IPS;
dash = strchr(start, '-');
if (colon && dash && dash > colon)
dash = NULL;
if (dash)
*dash = '\0';
ip = xtables_numeric_to_ip6addr(start);
if (!ip)
xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
start);
range->min_addr.in6 = *ip;
if (dash) {
ip = xtables_numeric_to_ip6addr(dash + 1);
if (!ip)
xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
dash+1);
range->max_addr.in6 = *ip;
} else
range->max_addr = range->min_addr;
free(arg);
return;
}
static void SNAT_parse(struct xt_option_call *cb)
{
const struct ip6t_entry *entry = cb->xt_entry;
struct nf_nat_range *range = cb->data;
int portok;
if (entry->ipv6.proto == IPPROTO_TCP ||
entry->ipv6.proto == IPPROTO_UDP ||
entry->ipv6.proto == IPPROTO_SCTP ||
entry->ipv6.proto == IPPROTO_DCCP ||
entry->ipv6.proto == IPPROTO_ICMP)
portok = 1;
else
portok = 0;
xtables_option_parse(cb);
switch (cb->entry->id) {
case O_TO_SRC:
if (cb->xflags & F_X_TO_SRC) {
if (!kernel_version)
get_kernel_version();
if (kernel_version > LINUX_VERSION(2, 6, 10))
xtables_error(PARAMETER_PROBLEM,
"SNAT: Multiple --to-source not supported");
}
parse_to(cb->arg, portok, range);
break;
case O_PERSISTENT:
range->flags |= NF_NAT_RANGE_PERSISTENT;
break;
}
}
static void SNAT_fcheck(struct xt_fcheck_call *cb)
{
static const unsigned int f = F_TO_SRC | F_RANDOM;
static const unsigned int r = F_TO_SRC | F_RANDOM_FULLY;
struct nf_nat_range *range = cb->data;
if ((cb->xflags & f) == f)
range->flags |= NF_NAT_RANGE_PROTO_RANDOM;
if ((cb->xflags & r) == r)
range->flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY;
}
static void print_range(const struct nf_nat_range *range)
{
if (range->flags & NF_NAT_RANGE_MAP_IPS) {
if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)
printf("[");
printf("%s", xtables_ip6addr_to_numeric(&range->min_addr.in6));
if (memcmp(&range->min_addr, &range->max_addr,
sizeof(range->min_addr)))
printf("-%s", xtables_ip6addr_to_numeric(&range->max_addr.in6));
if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)
printf("]");
}
if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
printf(":");
printf("%hu", ntohs(range->min_proto.tcp.port));
if (range->max_proto.tcp.port != range->min_proto.tcp.port)
printf("-%hu", ntohs(range->max_proto.tcp.port));
}
}
static void SNAT_print(const void *ip, const struct xt_entry_target *target,
int numeric)
{
const struct nf_nat_range *range = (const void *)target->data;
printf(" to:");
print_range(range);
if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" random");
if (range->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)
printf(" random-fully");
if (range->flags & NF_NAT_RANGE_PERSISTENT)
printf(" persistent");
}
static void SNAT_save(const void *ip, const struct xt_entry_target *target)
{
const struct nf_nat_range *range = (const void *)target->data;
printf(" --to-source ");
print_range(range);
if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" --random");
if (range->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)
printf(" --random-fully");
if (range->flags & NF_NAT_RANGE_PERSISTENT)
printf(" --persistent");
}
static struct xtables_target snat_tg_reg = {
.name = "SNAT",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV6,
.revision = 1,
.size = XT_ALIGN(sizeof(struct nf_nat_range)),
.userspacesize = XT_ALIGN(sizeof(struct nf_nat_range)),
.help = SNAT_help,
.x6_parse = SNAT_parse,
.x6_fcheck = SNAT_fcheck,
.print = SNAT_print,
.save = SNAT_save,
.x6_options = SNAT_opts,
};
void _init(void)
{
xtables_register_target(&snat_tg_reg);
}
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