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#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <xtables.h>
#include <iptables.h> /* get_kernel_version */
#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_DEST = 0,
O_RANDOM,
O_PERSISTENT,
O_X_TO_DEST, /* hidden flag */
F_TO_DEST = 1 << O_TO_DEST,
F_RANDOM = 1 << O_RANDOM,
F_X_TO_DEST = 1 << O_X_TO_DEST,
};
/* Dest NAT data consists of a multi-range, indicating where to map
to. */
struct ipt_natinfo
{
struct xt_entry_target t;
struct nf_nat_ipv4_multi_range_compat mr;
};
static void DNAT_help(void)
{
printf(
"DNAT target options:\n"
" --to-destination [<ipaddr>[-<ipaddr>]][:port[-port]]\n"
" Address to map destination to.\n"
"[--random] [--persistent]\n");
}
static void DNAT_help_v2(void)
{
printf(
"DNAT target options:\n"
" --to-destination [<ipaddr>[-<ipaddr>]][:port[-port[/port]]]\n"
" Address to map destination to.\n"
"[--random] [--persistent]\n");
}
static const struct xt_option_entry DNAT_opts[] = {
{.name = "to-destination", .id = O_TO_DEST, .type = XTTYPE_STRING,
.flags = XTOPT_MAND | XTOPT_MULTI},
{.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE},
{.name = "persistent", .id = O_PERSISTENT, .type = XTTYPE_NONE},
XTOPT_TABLEEND,
};
static struct ipt_natinfo *
append_range(struct ipt_natinfo *info, const struct nf_nat_ipv4_range *range)
{
unsigned int size;
/* One rangesize already in struct ipt_natinfo */
size = XT_ALIGN(sizeof(*info) + info->mr.rangesize * sizeof(*range));
info = realloc(info, size);
if (!info)
xtables_error(OTHER_PROBLEM, "Out of memory\n");
info->t.u.target_size = size;
info->mr.range[info->mr.rangesize] = *range;
info->mr.rangesize++;
return info;
}
/* Ranges expected in network order. */
static struct xt_entry_target *
parse_to(const char *orig_arg, int portok, struct ipt_natinfo *info)
{
struct nf_nat_ipv4_range range;
char *arg, *colon, *dash, *error;
const struct in_addr *ip;
arg = strdup(orig_arg);
if (arg == NULL)
xtables_error(RESOURCE_PROBLEM, "strdup");
memset(&range, 0, sizeof(range));
colon = strchr(arg, ':');
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.tcp.port
= range.max.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.tcp.port = htons(port);
range.max.tcp.port = htons(maxport);
}
/* Starts with a colon? No IP info...*/
if (colon == arg) {
free(arg);
return &(append_range(info, &range)->t);
}
*colon = '\0';
}
range.flags |= NF_NAT_RANGE_MAP_IPS;
dash = strchr(arg, '-');
if (colon && dash && dash > colon)
dash = NULL;
if (dash)
*dash = '\0';
ip = xtables_numeric_to_ipaddr(arg);
if (!ip)
xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
arg);
range.min_ip = ip->s_addr;
if (dash) {
ip = xtables_numeric_to_ipaddr(dash+1);
if (!ip)
xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
dash+1);
range.max_ip = ip->s_addr;
} else
range.max_ip = range.min_ip;
free(arg);
return &(append_range(info, &range)->t);
}
static void DNAT_parse(struct xt_option_call *cb)
{
const struct ipt_entry *entry = cb->xt_entry;
struct ipt_natinfo *info = (void *)(*cb->target);
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_DEST:
if (cb->xflags & F_X_TO_DEST) {
if (!kernel_version)
get_kernel_version();
if (kernel_version > LINUX_VERSION(2, 6, 10))
xtables_error(PARAMETER_PROBLEM,
"DNAT: Multiple --to-destination not supported");
}
*cb->target = parse_to(cb->arg, portok, info);
cb->xflags |= F_X_TO_DEST;
break;
case O_PERSISTENT:
info->mr.range[0].flags |= NF_NAT_RANGE_PERSISTENT;
break;
}
}
static void DNAT_fcheck(struct xt_fcheck_call *cb)
{
static const unsigned int f = F_TO_DEST | F_RANDOM;
struct nf_nat_ipv4_multi_range_compat *mr = cb->data;
if ((cb->xflags & f) == f)
mr->range[0].flags |= NF_NAT_RANGE_PROTO_RANDOM;
}
static void print_range(const struct nf_nat_ipv4_range *r)
{
if (r->flags & NF_NAT_RANGE_MAP_IPS) {
struct in_addr a;
a.s_addr = r->min_ip;
printf("%s", xtables_ipaddr_to_numeric(&a));
if (r->max_ip != r->min_ip) {
a.s_addr = r->max_ip;
printf("-%s", xtables_ipaddr_to_numeric(&a));
}
}
if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
printf(":");
printf("%hu", ntohs(r->min.tcp.port));
if (r->max.tcp.port != r->min.tcp.port)
printf("-%hu", ntohs(r->max.tcp.port));
}
}
static void DNAT_print(const void *ip, const struct xt_entry_target *target,
int numeric)
{
const struct ipt_natinfo *info = (const void *)target;
unsigned int i = 0;
printf(" to:");
for (i = 0; i < info->mr.rangesize; i++) {
print_range(&info->mr.range[i]);
if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" random");
if (info->mr.range[i].flags & NF_NAT_RANGE_PERSISTENT)
printf(" persistent");
}
}
static void DNAT_save(const void *ip, const struct xt_entry_target *target)
{
const struct ipt_natinfo *info = (const void *)target;
unsigned int i = 0;
for (i = 0; i < info->mr.rangesize; i++) {
printf(" --to-destination ");
print_range(&info->mr.range[i]);
if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" --random");
if (info->mr.range[i].flags & NF_NAT_RANGE_PERSISTENT)
printf(" --persistent");
}
}
static void print_range_xlate(const struct nf_nat_ipv4_range *r,
struct xt_xlate *xl)
{
if (r->flags & NF_NAT_RANGE_MAP_IPS) {
struct in_addr a;
a.s_addr = r->min_ip;
xt_xlate_add(xl, "%s", xtables_ipaddr_to_numeric(&a));
if (r->max_ip != r->min_ip) {
a.s_addr = r->max_ip;
xt_xlate_add(xl, "-%s", xtables_ipaddr_to_numeric(&a));
}
}
if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
xt_xlate_add(xl, ":%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));
}
}
static int DNAT_xlate(struct xt_xlate *xl,
const struct xt_xlate_tg_params *params)
{
const struct ipt_natinfo *info = (const void *)params->target;
unsigned int i = 0;
bool sep_need = false;
const char *sep = " ";
for (i = 0; i < info->mr.rangesize; i++) {
xt_xlate_add(xl, "dnat to ");
print_range_xlate(&info->mr.range[i], xl);
if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM) {
xt_xlate_add(xl, " random");
sep_need = true;
}
if (info->mr.range[i].flags & NF_NAT_RANGE_PERSISTENT) {
if (sep_need)
sep = ",";
xt_xlate_add(xl, "%spersistent", sep);
}
}
return 1;
}
static void
parse_to_v2(const char *orig_arg, int portok, struct nf_nat_range2 *range)
{
char *arg, *colon, *dash, *error;
const struct in_addr *ip;
arg = strdup(orig_arg);
if (arg == NULL)
xtables_error(RESOURCE_PROBLEM, "strdup");
colon = strchr(arg, ':');
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;
char *slash;
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);
slash = strchr(dash, '/');
if (slash) {
int baseport;
baseport = atoi(slash + 1);
if (baseport <= 0 || baseport > 65535)
xtables_error(PARAMETER_PROBLEM,
"Port `%s' not valid\n", slash+1);
range->flags |= NF_NAT_RANGE_PROTO_OFFSET;
range->base_proto.tcp.port = htons(baseport);
}
}
/* Starts with a colon? No IP info...*/
if (colon == arg) {
free(arg);
return;
}
*colon = '\0';
}
range->flags |= NF_NAT_RANGE_MAP_IPS;
dash = strchr(arg, '-');
if (colon && dash && dash > colon)
dash = NULL;
if (dash)
*dash = '\0';
ip = xtables_numeric_to_ipaddr(arg);
if (!ip)
xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
arg);
range->min_addr.in = *ip;
if (dash) {
ip = xtables_numeric_to_ipaddr(dash+1);
if (!ip)
xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
dash+1);
range->max_addr.in = *ip;
} else
range->max_addr = range->min_addr;
free(arg);
return;
}
static void DNAT_parse_v2(struct xt_option_call *cb)
{
const struct ipt_entry *entry = cb->xt_entry;
struct nf_nat_range2 *range = cb->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_DEST:
if (cb->xflags & F_X_TO_DEST) {
xtables_error(PARAMETER_PROBLEM,
"DNAT: Multiple --to-destination not supported");
}
parse_to_v2(cb->arg, portok, range);
cb->xflags |= F_X_TO_DEST;
break;
case O_PERSISTENT:
range->flags |= NF_NAT_RANGE_PERSISTENT;
break;
}
}
static void DNAT_fcheck_v2(struct xt_fcheck_call *cb)
{
static const unsigned int f = F_TO_DEST | F_RANDOM;
struct nf_nat_range2 *range = cb->data;
if ((cb->xflags & f) == f)
range->flags |= NF_NAT_RANGE_PROTO_RANDOM;
}
static void print_range_v2(const struct nf_nat_range2 *range)
{
if (range->flags & NF_NAT_RANGE_MAP_IPS) {
printf("%s", xtables_ipaddr_to_numeric(&range->min_addr.in));
if (memcmp(&range->min_addr, &range->max_addr,
sizeof(range->min_addr)))
printf("-%s", xtables_ipaddr_to_numeric(&range->max_addr.in));
}
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));
if (range->flags & NF_NAT_RANGE_PROTO_OFFSET)
printf("/%hu", ntohs(range->base_proto.tcp.port));
}
}
static void DNAT_print_v2(const void *ip, const struct xt_entry_target *target,
int numeric)
{
const struct nf_nat_range2 *range = (const void *)target->data;
printf(" to:");
print_range_v2(range);
if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" random");
if (range->flags & NF_NAT_RANGE_PERSISTENT)
printf(" persistent");
}
static void DNAT_save_v2(const void *ip, const struct xt_entry_target *target)
{
const struct nf_nat_range2 *range = (const void *)target->data;
printf(" --to-destination ");
print_range_v2(range);
if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" --random");
if (range->flags & NF_NAT_RANGE_PERSISTENT)
printf(" --persistent");
}
static void print_range_xlate_v2(const struct nf_nat_range2 *range,
struct xt_xlate *xl)
{
if (range->flags & NF_NAT_RANGE_MAP_IPS) {
xt_xlate_add(xl, "%s", xtables_ipaddr_to_numeric(&range->min_addr.in));
if (memcmp(&range->min_addr, &range->max_addr,
sizeof(range->min_addr))) {
xt_xlate_add(xl, "-%s", xtables_ipaddr_to_numeric(&range->max_addr.in));
}
}
if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
xt_xlate_add(xl, ":%hu", ntohs(range->min_proto.tcp.port));
if (range->max_proto.tcp.port != range->min_proto.tcp.port)
xt_xlate_add(xl, "-%hu", ntohs(range->max_proto.tcp.port));
if (range->flags & NF_NAT_RANGE_PROTO_OFFSET)
xt_xlate_add(xl, ";%hu", ntohs(range->base_proto.tcp.port));
}
}
static int DNAT_xlate_v2(struct xt_xlate *xl,
const struct xt_xlate_tg_params *params)
{
const struct nf_nat_range2 *range = (const void *)params->target->data;
bool sep_need = false;
const char *sep = " ";
xt_xlate_add(xl, "dnat to ");
print_range_xlate_v2(range, xl);
if (range->flags & NF_NAT_RANGE_PROTO_RANDOM) {
xt_xlate_add(xl, " random");
sep_need = true;
}
if (range->flags & NF_NAT_RANGE_PERSISTENT) {
if (sep_need)
sep = ",";
xt_xlate_add(xl, "%spersistent", sep);
}
return 1;
}
static struct xtables_target dnat_tg_reg[] = {
{
.name = "DNAT",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV4,
.revision = 0,
.size = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)),
.userspacesize = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)),
.help = DNAT_help,
.print = DNAT_print,
.save = DNAT_save,
.x6_parse = DNAT_parse,
.x6_fcheck = DNAT_fcheck,
.x6_options = DNAT_opts,
.xlate = DNAT_xlate,
},
{
.name = "DNAT",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV4,
.revision = 2,
.size = XT_ALIGN(sizeof(struct nf_nat_range2)),
.userspacesize = XT_ALIGN(sizeof(struct nf_nat_range2)),
.help = DNAT_help_v2,
.print = DNAT_print_v2,
.save = DNAT_save_v2,
.x6_parse = DNAT_parse_v2,
.x6_fcheck = DNAT_fcheck_v2,
.x6_options = DNAT_opts,
.xlate = DNAT_xlate_v2,
},
};
void _init(void)
{
xtables_register_targets(dnat_tg_reg, ARRAY_SIZE(dnat_tg_reg));
}
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