/* 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);

}