/*
 * Copyright 2011, Siemens AG
 * written by Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
 */

/* Based on patches from Jon Smirl <jonsmirl@gmail.com>
 * Copyright (c) 2011 Jon Smirl <jonsmirl@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

/* Jon's code is based on 6lowpan implementation for Contiki which is:
 * Copyright (c) 2008, Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <linux/bitops.h>
#include <linux/if_arp.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <net/6lowpan.h>
#include <net/ipv6.h>
#include <net/af_ieee802154.h>

#include "nhc.h"

/* Uncompress address function for source and
 * destination address(non-multicast).
 *
 * address_mode is sam value or dam value.
 */
static int uncompress_addr(struct sk_buff *skb,
                           struct in6_addr *ipaddr, const u8 address_mode,
                           const u8 *lladdr, const u8 addr_type,
                           const u8 addr_len)
{
        bool fail;

        switch (address_mode) {
        case LOWPAN_IPHC_ADDR_00:
                /* for global link addresses */
                fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
                break;
        case LOWPAN_IPHC_ADDR_01:
                /* fe:80::XXXX:XXXX:XXXX:XXXX */
                ipaddr->s6_addr[0] = 0xFE;
                ipaddr->s6_addr[1] = 0x80;
                fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
                break;
        case LOWPAN_IPHC_ADDR_02:
                /* fe:80::ff:fe00:XXXX */
                ipaddr->s6_addr[0] = 0xFE;
                ipaddr->s6_addr[1] = 0x80;
                ipaddr->s6_addr[11] = 0xFF;
                ipaddr->s6_addr[12] = 0xFE;
                fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
                break;
        case LOWPAN_IPHC_ADDR_03:
                fail = false;
                switch (addr_type) {
                case IEEE802154_ADDR_LONG:
                        /* fe:80::XXXX:XXXX:XXXX:XXXX
                         *        \_________________/
                         *              hwaddr
                         */
                        ipaddr->s6_addr[0] = 0xFE;
                        ipaddr->s6_addr[1] = 0x80;
                        memcpy(&ipaddr->s6_addr[8], lladdr, addr_len);
                        /* second bit-flip (Universe/Local)
                         * is done according RFC2464
                         */
                        ipaddr->s6_addr[8] ^= 0x02;
                        break;
                case IEEE802154_ADDR_SHORT:
                        /* fe:80::ff:fe00:XXXX
                         *                \__/
                         *             short_addr
                         *
                         * Universe/Local bit is zero.
                         */
                        ipaddr->s6_addr[0] = 0xFE;
                        ipaddr->s6_addr[1] = 0x80;
                        ipaddr->s6_addr[11] = 0xFF;
                        ipaddr->s6_addr[12] = 0xFE;
                        ipaddr->s6_addr16[7] = htons(*((u16 *)lladdr));
                        break;
                default:
                        pr_debug("Invalid addr_type set\n");
                        return -EINVAL;
                }
                break;
        default:
                pr_debug("Invalid address mode value: 0x%x\n", address_mode);
                return -EINVAL;
        }

        if (fail) {
                pr_debug("Failed to fetch skb data\n");
                return -EIO;
        }

        raw_dump_inline(NULL, "Reconstructed ipv6 addr is",
                        ipaddr->s6_addr, 16);

        return 0;
}

/* Uncompress address function for source context
 * based address(non-multicast).
 */
static int uncompress_context_based_src_addr(struct sk_buff *skb,
                                             struct in6_addr *ipaddr,
                                             const u8 sam)
{
        switch (sam) {
        case LOWPAN_IPHC_ADDR_00:
                /* unspec address ::
                 * Do nothing, address is already ::
                 */
                break;
        case LOWPAN_IPHC_ADDR_01:
                /* TODO */
        case LOWPAN_IPHC_ADDR_02:
                /* TODO */
        case LOWPAN_IPHC_ADDR_03:
                /* TODO */
                netdev_warn(skb->dev, "SAM value 0x%x not supported\n", sam);
                return -EINVAL;
        default:
                pr_debug("Invalid sam value: 0x%x\n", sam);
                return -EINVAL;
        }

        raw_dump_inline(NULL,
                        "Reconstructed context based ipv6 src addr is",
                        ipaddr->s6_addr, 16);

        return 0;
}

/* Uncompress function for multicast destination address,
 * when M bit is set.
 */
static int lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
                                             struct in6_addr *ipaddr,
                                             const u8 dam)
{
        bool fail;

        switch (dam) {
        case LOWPAN_IPHC_DAM_00:
                /* 00:  128 bits.  The full address
                 * is carried in-line.
                 */
                fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
                break;
        case LOWPAN_IPHC_DAM_01:
                /* 01:  48 bits.  The address takes
                 * the form ffXX::00XX:XXXX:XXXX.
                 */
                ipaddr->s6_addr[0] = 0xFF;
                fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
                fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);
                break;
        case LOWPAN_IPHC_DAM_10:
                /* 10:  32 bits.  The address takes
                 * the form ffXX::00XX:XXXX.
                 */
                ipaddr->s6_addr[0] = 0xFF;
                fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
                fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);
                break;
        case LOWPAN_IPHC_DAM_11:
                /* 11:  8 bits.  The address takes
                 * the form ff02::00XX.
                 */
                ipaddr->s6_addr[0] = 0xFF;
                ipaddr->s6_addr[1] = 0x02;
                fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);
                break;
        default:
                pr_debug("DAM value has a wrong value: 0x%x\n", dam);
                return -EINVAL;
        }

        if (fail) {
                pr_debug("Failed to fetch skb data\n");
                return -EIO;
        }

        raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is",
                        ipaddr->s6_addr, 16);

        return 0;
}

/* TTL uncompression values */
static const u8 lowpan_ttl_values[] = { 0, 1, 64, 255 };

int
lowpan_header_decompress(struct sk_buff *skb, struct net_device *dev,
                         const u8 *saddr, const u8 saddr_type,
                         const u8 saddr_len, const u8 *daddr,
                         const u8 daddr_type, const u8 daddr_len,
                         u8 iphc0, u8 iphc1)
{
        struct ipv6hdr hdr = {};
        u8 tmp, num_context = 0;
        int err;

        raw_dump_table(__func__, "raw skb data dump uncompressed",
                       skb->data, skb->len);

        /* another if the CID flag is set */
        if (iphc1 & LOWPAN_IPHC_CID) {
                pr_debug("CID flag is set, increase header with one\n");
                if (lowpan_fetch_skb(skb, &num_context, sizeof(num_context)))
                        return -EINVAL;
        }

        hdr.version = 6;

        /* Traffic Class and Flow Label */
        switch ((iphc0 & LOWPAN_IPHC_TF) >> 3) {
        /* Traffic Class and FLow Label carried in-line
         * ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
         */
        case 0: /* 00b */
                if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
                        return -EINVAL;

                memcpy(&hdr.flow_lbl, &skb->data[0], 3);
                skb_pull(skb, 3);
                hdr.priority = ((tmp >> 2) & 0x0f);
                hdr.flow_lbl[0] = ((tmp >> 2) & 0x30) | (tmp << 6) |
                                        (hdr.flow_lbl[0] & 0x0f);
                break;
        /* Traffic class carried in-line
         * ECN + DSCP (1 byte), Flow Label is elided
         */
        case 2: /* 10b */
                if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
                        return -EINVAL;

                hdr.priority = ((tmp >> 2) & 0x0f);
                hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
                break;
        /* Flow Label carried in-line
         * ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
         */
        case 1: /* 01b */
                if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
                        return -EINVAL;

                hdr.flow_lbl[0] = (skb->data[0] & 0x0F) | ((tmp >> 2) & 0x30);
                memcpy(&hdr.flow_lbl[1], &skb->data[0], 2);
                skb_pull(skb, 2);
                break;
        /* Traffic Class and Flow Label are elided */
        case 3: /* 11b */
                break;
        default:
                break;
        }

        /* Next Header */
        if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
                /* Next header is carried inline */
                if (lowpan_fetch_skb(skb, &hdr.nexthdr, sizeof(hdr.nexthdr)))
                        return -EINVAL;

                pr_debug("NH flag is set, next header carried inline: %02x\n",
                         hdr.nexthdr);
        }

        /* Hop Limit */
        if ((iphc0 & 0x03) != LOWPAN_IPHC_TTL_I) {
                hdr.hop_limit = lowpan_ttl_values[iphc0 & 0x03];
        } else {
                if (lowpan_fetch_skb(skb, &hdr.hop_limit,
                                     sizeof(hdr.hop_limit)))
                        return -EINVAL;
        }

        /* Extract SAM to the tmp variable */
        tmp = ((iphc1 & LOWPAN_IPHC_SAM) >> LOWPAN_IPHC_SAM_BIT) & 0x03;

        if (iphc1 & LOWPAN_IPHC_SAC) {
                /* Source address context based uncompression */
                pr_debug("SAC bit is set. Handle context based source address.\n");
                err = uncompress_context_based_src_addr(skb, &hdr.saddr, tmp);
        } else {
                /* Source address uncompression */
                pr_debug("source address stateless compression\n");
                err = uncompress_addr(skb, &hdr.saddr, tmp, saddr,
                                      saddr_type, saddr_len);
        }

        /* Check on error of previous branch */
        if (err)
                return -EINVAL;

        /* Extract DAM to the tmp variable */
        tmp = ((iphc1 & LOWPAN_IPHC_DAM_11) >> LOWPAN_IPHC_DAM_BIT) & 0x03;

        /* check for Multicast Compression */
        if (iphc1 & LOWPAN_IPHC_M) {
                if (iphc1 & LOWPAN_IPHC_DAC) {
                        pr_debug("dest: context-based mcast compression\n");
                        /* TODO: implement this */
                } else {
                        err = lowpan_uncompress_multicast_daddr(skb, &hdr.daddr,
                                                                tmp);

                        if (err)
                                return -EINVAL;
                }
        } else {
                err = uncompress_addr(skb, &hdr.daddr, tmp, daddr,
                                      daddr_type, daddr_len);
                pr_debug("dest: stateless compression mode %d dest %pI6c\n",
                         tmp, &hdr.daddr);
                if (err)
                        return -EINVAL;
        }

        /* Next header data uncompression */
        if (iphc0 & LOWPAN_IPHC_NH_C) {
                err = lowpan_nhc_do_uncompression(skb, dev, &hdr);
                if (err < 0)
                        return err;
        } else {
                err = skb_cow(skb, sizeof(hdr));
                if (unlikely(err))
                        return err;
        }

        hdr.payload_len = htons(skb->len);

        pr_debug("skb headroom size = %d, data length = %d\n",
                 skb_headroom(skb), skb->len);

        pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n\t"
                 "nexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
                hdr.version, ntohs(hdr.payload_len), hdr.nexthdr,
                hdr.hop_limit, &hdr.daddr);

        skb_push(skb, sizeof(hdr));
        skb_reset_network_header(skb);
        skb_copy_to_linear_data(skb, &hdr, sizeof(hdr));

        raw_dump_table(__func__, "raw header dump", (u8 *)&hdr, sizeof(hdr));

        return 0;
}
EXPORT_SYMBOL_GPL(lowpan_header_decompress);

static u8 lowpan_compress_addr_64(u8 **hc_ptr, u8 shift,
                                  const struct in6_addr *ipaddr,
                                  const unsigned char *lladdr)
{
        u8 val = 0;

        if (is_addr_mac_addr_based(ipaddr, lladdr)) {
                val = 3; /* 0-bits */
                pr_debug("address compression 0 bits\n");
        } else if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
                /* compress IID to 16 bits xxxx::XXXX */
                lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[7], 2);
                val = 2; /* 16-bits */
                raw_dump_inline(NULL, "Compressed ipv6 addr is (16 bits)",
                                *hc_ptr - 2, 2);
        } else {
                /* do not compress IID => xxxx::IID */
                lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[4], 8);
                val = 1; /* 64-bits */
                raw_dump_inline(NULL, "Compressed ipv6 addr is (64 bits)",
                                *hc_ptr - 8, 8);
        }

        return rol8(val, shift);
}

int lowpan_header_compress(struct sk_buff *skb, struct net_device *dev,
                           unsigned short type, const void *_daddr,
                           const void *_saddr, unsigned int len)
{
        u8 tmp, iphc0, iphc1, *hc_ptr;
        struct ipv6hdr *hdr;
        u8 head[100] = {};
        int ret, addr_type;

        if (type != ETH_P_IPV6)
                return -EINVAL;

        hdr = ipv6_hdr(skb);
        hc_ptr = head + 2;

        pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n"
                 "\tnexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
                 hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
                 hdr->hop_limit, &hdr->daddr);

        raw_dump_table(__func__, "raw skb network header dump",
                       skb_network_header(skb), sizeof(struct ipv6hdr));

        /* As we copy some bit-length fields, in the IPHC encoding bytes,
         * we sometimes use |=
         * If the field is 0, and the current bit value in memory is 1,
         * this does not work. We therefore reset the IPHC encoding here
         */
        iphc0 = LOWPAN_DISPATCH_IPHC;
        iphc1 = 0;

        /* TODO: context lookup */

        raw_dump_inline(__func__, "saddr",
                        (unsigned char *)_saddr, IEEE802154_ADDR_LEN);
        raw_dump_inline(__func__, "daddr",
                        (unsigned char *)_daddr, IEEE802154_ADDR_LEN);

        raw_dump_table(__func__, "sending raw skb network uncompressed packet",
                       skb->data, skb->len);

        /* Traffic class, flow label
         * If flow label is 0, compress it. If traffic class is 0, compress it
         * We have to process both in the same time as the offset of traffic
         * class depends on the presence of version and flow label
         */

        /* hc format of TC is ECN | DSCP , original one is DSCP | ECN */
        tmp = (hdr->priority << 4) | (hdr->flow_lbl[0] >> 4);
        tmp = ((tmp & 0x03) << 6) | (tmp >> 2);

        if (((hdr->flow_lbl[0] & 0x0F) == 0) &&
            (hdr->flow_lbl[1] == 0) && (hdr->flow_lbl[2] == 0)) {
                /* flow label can be compressed */
                iphc0 |= LOWPAN_IPHC_FL_C;
                if ((hdr->priority == 0) &&
                    ((hdr->flow_lbl[0] & 0xF0) == 0)) {
                        /* compress (elide) all */
                        iphc0 |= LOWPAN_IPHC_TC_C;
                } else {
                        /* compress only the flow label */
                        *hc_ptr = tmp;
                        hc_ptr += 1;
                }
        } else {
                /* Flow label cannot be compressed */
                if ((hdr->priority == 0) &&
                    ((hdr->flow_lbl[0] & 0xF0) == 0)) {
                        /* compress only traffic class */
                        iphc0 |= LOWPAN_IPHC_TC_C;
                        *hc_ptr = (tmp & 0xc0) | (hdr->flow_lbl[0] & 0x0F);
                        memcpy(hc_ptr + 1, &hdr->flow_lbl[1], 2);
                        hc_ptr += 3;
                } else {
                        /* compress nothing */
                        memcpy(hc_ptr, hdr, 4);
                        /* replace the top byte with new ECN | DSCP format */
                        *hc_ptr = tmp;
                        hc_ptr += 4;
                }
        }

        /* NOTE: payload length is always compressed */

        /* Check if we provide the nhc format for nexthdr and compression
         * functionality. If not nexthdr is handled inline and not compressed.
         */
        ret = lowpan_nhc_check_compression(skb, hdr, &hc_ptr, &iphc0);
        if (ret < 0)
                return ret;

        /* Hop limit
         * if 1:   compress, encoding is 01
         * if 64:  compress, encoding is 10
         * if 255: compress, encoding is 11
         * else do not compress
         */
        switch (hdr->hop_limit) {
        case 1:
                iphc0 |= LOWPAN_IPHC_TTL_1;
                break;
        case 64:
                iphc0 |= LOWPAN_IPHC_TTL_64;
                break;
        case 255:
                iphc0 |= LOWPAN_IPHC_TTL_255;
                break;
        default:
                lowpan_push_hc_data(&hc_ptr, &hdr->hop_limit,
                                    sizeof(hdr->hop_limit));
        }

        addr_type = ipv6_addr_type(&hdr->saddr);
        /* source address compression */
        if (addr_type == IPV6_ADDR_ANY) {
                pr_debug("source address is unspecified, setting SAC\n");
                iphc1 |= LOWPAN_IPHC_SAC;
        } else {
                if (addr_type & IPV6_ADDR_LINKLOCAL) {
                        iphc1 |= lowpan_compress_addr_64(&hc_ptr,
                                                         LOWPAN_IPHC_SAM_BIT,
                                                         &hdr->saddr, _saddr);
                        pr_debug("source address unicast link-local %pI6c iphc1 0x%02x\n",
                                 &hdr->saddr, iphc1);
                } else {
                        pr_debug("send the full source address\n");
                        lowpan_push_hc_data(&hc_ptr, hdr->saddr.s6_addr, 16);
                }
        }

        addr_type = ipv6_addr_type(&hdr->daddr);
        /* destination address compression */
        if (addr_type & IPV6_ADDR_MULTICAST) {
                pr_debug("destination address is multicast: ");
                iphc1 |= LOWPAN_IPHC_M;
                if (lowpan_is_mcast_addr_compressable8(&hdr->daddr)) {
                        pr_debug("compressed to 1 octet\n");
                        iphc1 |= LOWPAN_IPHC_DAM_11;
                        /* use last byte */
                        lowpan_push_hc_data(&hc_ptr,
                                            &hdr->daddr.s6_addr[15], 1);
                } else if (lowpan_is_mcast_addr_compressable32(&hdr->daddr)) {
                        pr_debug("compressed to 4 octets\n");
                        iphc1 |= LOWPAN_IPHC_DAM_10;
                        /* second byte + the last three */
                        lowpan_push_hc_data(&hc_ptr,
                                            &hdr->daddr.s6_addr[1], 1);
                        lowpan_push_hc_data(&hc_ptr,
                                            &hdr->daddr.s6_addr[13], 3);
                } else if (lowpan_is_mcast_addr_compressable48(&hdr->daddr)) {
                        pr_debug("compressed to 6 octets\n");
                        iphc1 |= LOWPAN_IPHC_DAM_01;
                        /* second byte + the last five */
                        lowpan_push_hc_data(&hc_ptr,
                                            &hdr->daddr.s6_addr[1], 1);
                        lowpan_push_hc_data(&hc_ptr,
                                            &hdr->daddr.s6_addr[11], 5);
                } else {
                        pr_debug("using full address\n");
                        iphc1 |= LOWPAN_IPHC_DAM_00;
                        lowpan_push_hc_data(&hc_ptr, hdr->daddr.s6_addr, 16);
                }
        } else {
                if (addr_type & IPV6_ADDR_LINKLOCAL) {
                        /* TODO: context lookup */
                        iphc1 |= lowpan_compress_addr_64(&hc_ptr,
                                LOWPAN_IPHC_DAM_BIT, &hdr->daddr, _daddr);
                        pr_debug("dest address unicast link-local %pI6c "
                                 "iphc1 0x%02x\n", &hdr->daddr, iphc1);
                } else {
                        pr_debug("dest address unicast %pI6c\n", &hdr->daddr);
                        lowpan_push_hc_data(&hc_ptr, hdr->daddr.s6_addr, 16);
                }
        }

        /* next header compression */
        if (iphc0 & LOWPAN_IPHC_NH_C) {
                ret = lowpan_nhc_do_compression(skb, hdr, &hc_ptr);
                if (ret < 0)
                        return ret;
        }

        head[0] = iphc0;
        head[1] = iphc1;

        skb_pull(skb, sizeof(struct ipv6hdr));
        skb_reset_transport_header(skb);
        memcpy(skb_push(skb, hc_ptr - head), head, hc_ptr - head);
        skb_reset_network_header(skb);

        pr_debug("header len %d skb %u\n", (int)(hc_ptr - head), skb->len);

        raw_dump_table(__func__, "raw skb data dump compressed",
                       skb->data, skb->len);
        return 0;
}
EXPORT_SYMBOL_GPL(lowpan_header_compress);

static int __init lowpan_module_init(void)
{
        request_module_nowait("nhc_dest");
        request_module_nowait("nhc_fragment");
        request_module_nowait("nhc_hop");
        request_module_nowait("nhc_ipv6");
        request_module_nowait("nhc_mobility");
        request_module_nowait("nhc_routing");
        request_module_nowait("nhc_udp");

        return 0;
}
module_init(lowpan_module_init);

MODULE_LICENSE("GPL");