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/* ipv6header match - matches IPv6 packets based
on whether they contain certain headers */
/* Original idea: Brad Chapman
* Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> */
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <xtables.h>
#include <linux/netfilter_ipv6/ip6t_ipv6header.h>
enum {
O_HEADER = 0,
O_SOFT,
};
/* A few hardcoded protocols for 'all' and in case the user has no
* /etc/protocols */
struct pprot {
char *name;
uint8_t num;
};
struct numflag {
uint8_t proto;
uint8_t flag;
};
static const struct pprot chain_protos[] = {
{ "hop-by-hop", IPPROTO_HOPOPTS },
{ "protocol", IPPROTO_RAW },
{ "hop", IPPROTO_HOPOPTS },
{ "dst", IPPROTO_DSTOPTS },
{ "route", IPPROTO_ROUTING },
{ "frag", IPPROTO_FRAGMENT },
{ "auth", IPPROTO_AH },
{ "esp", IPPROTO_ESP },
{ "none", IPPROTO_NONE },
{ "prot", IPPROTO_RAW },
{ "0", IPPROTO_HOPOPTS },
{ "60", IPPROTO_DSTOPTS },
{ "43", IPPROTO_ROUTING },
{ "44", IPPROTO_FRAGMENT },
{ "51", IPPROTO_AH },
{ "50", IPPROTO_ESP },
{ "59", IPPROTO_NONE },
{ "255", IPPROTO_RAW },
/* { "all", 0 }, */
};
static const struct numflag chain_flags[] = {
{ IPPROTO_HOPOPTS, MASK_HOPOPTS },
{ IPPROTO_DSTOPTS, MASK_DSTOPTS },
{ IPPROTO_ROUTING, MASK_ROUTING },
{ IPPROTO_FRAGMENT, MASK_FRAGMENT },
{ IPPROTO_AH, MASK_AH },
{ IPPROTO_ESP, MASK_ESP },
{ IPPROTO_NONE, MASK_NONE },
{ IPPROTO_RAW, MASK_PROTO },
};
static const char *
proto_to_name(uint8_t proto, int nolookup)
{
unsigned int i;
if (proto && !nolookup) {
const struct protoent *pent = getprotobynumber(proto);
if (pent)
return pent->p_name;
}
for (i = 0; i < ARRAY_SIZE(chain_protos); ++i)
if (chain_protos[i].num == proto)
return chain_protos[i].name;
return NULL;
}
static uint16_t
name_to_proto(const char *s)
{
unsigned int proto=0;
const struct protoent *pent;
if ((pent = getprotobyname(s)))
proto = pent->p_proto;
else {
unsigned int i;
for (i = 0; i < ARRAY_SIZE(chain_protos); ++i)
if (strcmp(s, chain_protos[i].name) == 0) {
proto = chain_protos[i].num;
break;
}
if (i == ARRAY_SIZE(chain_protos))
xtables_error(PARAMETER_PROBLEM,
"unknown header `%s' specified",
s);
}
return proto;
}
static unsigned int
add_proto_to_mask(int proto){
unsigned int i=0, flag=0;
for (i = 0; i < ARRAY_SIZE(chain_flags); ++i)
if (proto == chain_flags[i].proto){
flag = chain_flags[i].flag;
break;
}
if (i == ARRAY_SIZE(chain_flags))
xtables_error(PARAMETER_PROBLEM,
"unknown header `%d' specified",
proto);
return flag;
}
static void ipv6header_help(void)
{
printf(
"ipv6header match options:\n"
"[!] --header headers Type of header to match, by name\n"
" names: hop,dst,route,frag,auth,esp,none,prot\n"
" long names: hop-by-hop,ipv6-opts,ipv6-route,\n"
" ipv6-frag,ah,esp,ipv6-nonxt,protocol\n"
" numbers: 0,60,43,44,51,50,59\n"
"--soft The header CONTAINS the specified extensions\n");
}
static const struct xt_option_entry ipv6header_opts[] = {
{.name = "header", .id = O_HEADER, .type = XTTYPE_STRING,
.flags = XTOPT_MAND | XTOPT_INVERT},
{.name = "soft", .id = O_SOFT, .type = XTTYPE_NONE},
XTOPT_TABLEEND,
};
static unsigned int
parse_header(const char *flags) {
unsigned int ret = 0;
char *ptr;
char *buffer;
buffer = strdup(flags);
for (ptr = strtok(buffer, ","); ptr; ptr = strtok(NULL, ","))
ret |= add_proto_to_mask(name_to_proto(ptr));
free(buffer);
return ret;
}
static void ipv6header_parse(struct xt_option_call *cb)
{
struct ip6t_ipv6header_info *info = cb->data;
xtables_option_parse(cb);
switch (cb->entry->id) {
case O_HEADER:
if (!(info->matchflags = parse_header(cb->arg)))
xtables_error(PARAMETER_PROBLEM, "ip6t_ipv6header: cannot parse header names");
if (cb->invert)
info->invflags |= 0xFF;
break;
case O_SOFT:
info->modeflag |= 0xFF;
break;
}
}
static void
print_header(uint8_t flags){
int have_flag = 0;
while (flags) {
unsigned int i;
for (i = 0; (flags & chain_flags[i].flag) == 0; i++);
if (have_flag)
printf(",");
printf("%s", proto_to_name(chain_flags[i].proto,0));
have_flag = 1;
flags &= ~chain_flags[i].flag;
}
if (!have_flag)
printf("NONE");
}
static void ipv6header_print(const void *ip,
const struct xt_entry_match *match, int numeric)
{
const struct ip6t_ipv6header_info *info = (const struct ip6t_ipv6header_info *)match->data;
printf(" ipv6header");
if (info->matchflags || info->invflags) {
printf(" flags:%s", info->invflags ? "!" : "");
if (numeric)
printf("0x%02X", info->matchflags);
else {
print_header(info->matchflags);
}
}
if (info->modeflag)
printf(" soft");
}
static void ipv6header_save(const void *ip, const struct xt_entry_match *match)
{
const struct ip6t_ipv6header_info *info = (const struct ip6t_ipv6header_info *)match->data;
printf("%s --header ", info->invflags ? " !" : "");
print_header(info->matchflags);
if (info->modeflag)
printf(" --soft");
}
static struct xtables_match ipv6header_mt6_reg = {
.name = "ipv6header",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV6,
.size = XT_ALIGN(sizeof(struct ip6t_ipv6header_info)),
.userspacesize = XT_ALIGN(sizeof(struct ip6t_ipv6header_info)),
.help = ipv6header_help,
.print = ipv6header_print,
.save = ipv6header_save,
.x6_parse = ipv6header_parse,
.x6_options = ipv6header_opts,
};
void _init(void)
{
xtables_register_match(&ipv6header_mt6_reg);
}
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