/* 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/moduleparam.h>
  #include <linux/netdevice.h>
  #include <net/af_ieee802154.h>
  #include <net/ieee802154.h>
  #include <net/ieee802154_netdev.h>

  #include <net/6lowpan.h>

  #include <net/ipv6.h>

  #include "reassembly.h"

  static LIST_HEAD(lowpan_devices);

  /* private device info */
  struct lowpan_dev_info {
  	struct net_device	*real_dev; /* real WPAN device ptr */
  	struct mutex		dev_list_mtx; /* mutex for list ops */

  	__be16			fragment_tag;

  };
  
  struct lowpan_dev_record {
  	struct net_device *ldev;
  	struct list_head list;
  };
  
  static inline struct
  lowpan_dev_info *lowpan_dev_info(const struct net_device *dev)
  {
  	return netdev_priv(dev);
  }
  
  static inline void lowpan_address_flip(u8 *src, u8 *dest)
  {
  	int i;
  	for (i = 0; i < IEEE802154_ADDR_LEN; i++)
  		(dest)[IEEE802154_ADDR_LEN - i - 1] = (src)[i];
  }

  static int lowpan_header_create(struct sk_buff *skb,
  			   struct net_device *dev,
  			   unsigned short type, const void *_daddr,

  			   const void *_saddr, unsigned int len)

  {

  	const u8 *saddr = _saddr;
  	const u8 *daddr = _daddr;

  	struct ieee802154_addr sa, da;

  	/* TODO:
  	 * if this package isn't ipv6 one, where should it be routed?
  	 */

  	if (type != ETH_P_IPV6)
  		return 0;

  	if (!saddr)
  		saddr = dev->dev_addr;

  	raw_dump_inline(__func__, "saddr", (unsigned char *)saddr, 8);
  	raw_dump_inline(__func__, "daddr", (unsigned char *)daddr, 8);

  	lowpan_header_compress(skb, dev, type, daddr, saddr, len);

  	/* NOTE1: I'm still unsure about the fact that compression and WPAN

  	 * header are created here and not later in the xmit. So wait for
  	 * an opinion of net maintainers.
  	 */

  	/* NOTE2: to be absolutely correct, we must derive PANid information

  	 * from MAC subif of the 'dev' and 'real_dev' network devices, but
  	 * this isn't implemented in mainline yet, so currently we assign 0xff
  	 */

  	mac_cb(skb)->flags = IEEE802154_FC_TYPE_DATA;
  	mac_cb(skb)->seq = ieee802154_mlme_ops(dev)->get_dsn(dev);

  	/* prepare wpan address data */

  	sa.mode = IEEE802154_ADDR_LONG;
  	sa.pan_id = ieee802154_mlme_ops(dev)->get_pan_id(dev);
  	sa.extended_addr = ieee802154_devaddr_from_raw(saddr);

  	/* intra-PAN communications */

  	da.pan_id = sa.pan_id;

  	/* if the destination address is the broadcast address, use the

  	 * corresponding short address
  	 */
  	if (lowpan_is_addr_broadcast(daddr)) {

  		da.mode = IEEE802154_ADDR_SHORT;
  		da.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);

  	} else {

  		da.mode = IEEE802154_ADDR_LONG;
  		da.extended_addr = ieee802154_devaddr_from_raw(daddr);

  		/* request acknowledgment */
  		mac_cb(skb)->flags |= MAC_CB_FLAG_ACKREQ;

  	}

  
  	return dev_hard_header(skb, lowpan_dev_info(dev)->real_dev,

  			type, (void *)&da, (void *)&sa, 0);

  }

  static int lowpan_give_skb_to_devices(struct sk_buff *skb,
  					struct net_device *dev)

  {
  	struct lowpan_dev_record *entry;
  	struct sk_buff *skb_cp;
  	int stat = NET_RX_SUCCESS;
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(entry, &lowpan_devices, list)
  		if (lowpan_dev_info(entry->ldev)->real_dev == skb->dev) {
  			skb_cp = skb_copy(skb, GFP_ATOMIC);
  			if (!skb_cp) {
  				stat = -ENOMEM;
  				break;
  			}
  
  			skb_cp->dev = entry->ldev;
  			stat = netif_rx(skb_cp);
  		}
  	rcu_read_unlock();
  
  	return stat;
  }

  static int process_data(struct sk_buff *skb, const struct ieee802154_hdr *hdr)

  {

  	u8 iphc0, iphc1;

  	struct ieee802154_addr_sa sa, da;
  	void *sap, *dap;

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

  	/* at least two bytes will be used for the encoding */
  	if (skb->len < 2)
  		goto drop;

  
  	if (lowpan_fetch_skb_u8(skb, &iphc0))
  		goto drop;

  	if (lowpan_fetch_skb_u8(skb, &iphc1))
  		goto drop;

  	ieee802154_addr_to_sa(&sa, &hdr->source);
  	ieee802154_addr_to_sa(&da, &hdr->dest);

  	if (sa.addr_type == IEEE802154_ADDR_SHORT)
  		sap = &sa.short_addr;
  	else
  		sap = &sa.hwaddr;
  
  	if (da.addr_type == IEEE802154_ADDR_SHORT)
  		dap = &da.short_addr;
  	else
  		dap = &da.hwaddr;
  
  	return lowpan_process_data(skb, skb->dev, sap, sa.addr_type,
  				   IEEE802154_ADDR_LEN, dap, da.addr_type,
  				   IEEE802154_ADDR_LEN, iphc0, iphc1,
  				   lowpan_give_skb_to_devices);

  drop:

  	kfree_skb(skb);

  	return -EINVAL;
  }

  static int lowpan_set_address(struct net_device *dev, void *p)
  {
  	struct sockaddr *sa = p;
  
  	if (netif_running(dev))
  		return -EBUSY;
  
  	/* TODO: validate addr */
  	memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
  
  	return 0;
  }

  static int
  lowpan_fragment_xmit(struct sk_buff *skb, u8 *head,

  		     int mlen, int plen, int offset, int type)

  {
  	struct sk_buff *frag;

  	int hlen;

  	hlen = (type == LOWPAN_DISPATCH_FRAG1) ?
  			LOWPAN_FRAG1_HEAD_SIZE : LOWPAN_FRAGN_HEAD_SIZE;

  	raw_dump_inline(__func__, "6lowpan fragment header", head, hlen);

  	frag = netdev_alloc_skb(skb->dev,
  				hlen + mlen + plen + IEEE802154_MFR_SIZE);

  	if (!frag)
  		return -ENOMEM;
  
  	frag->priority = skb->priority;

  
  	/* copy header, MFR and payload */

  	skb_put(frag, mlen);
  	skb_copy_to_linear_data(frag, skb_mac_header(skb), mlen);

  	skb_put(frag, hlen);
  	skb_copy_to_linear_data_offset(frag, mlen, head, hlen);
  
  	skb_put(frag, plen);
  	skb_copy_to_linear_data_offset(frag, mlen + hlen,
  				       skb_network_header(skb) + offset, plen);

  	raw_dump_table(__func__, " raw fragment dump", frag->data, frag->len);

  	return dev_queue_xmit(frag);

  }
  
  static int

  lowpan_skb_fragmentation(struct sk_buff *skb, struct net_device *dev)

  {

  	int err;
  	u16 dgram_offset, dgram_size, payload_length, header_length,

  	    lowpan_size, frag_plen, offset;
  	__be16 tag;

  	u8 head[5];

  	header_length = skb->mac_len;

  	payload_length = skb->len - header_length;

  	tag = lowpan_dev_info(dev)->fragment_tag++;

  	lowpan_size = skb_network_header_len(skb);
  	dgram_size = lowpan_uncompress_size(skb, &dgram_offset) -
  		     header_length;

  
  	/* first fragment header */

  	head[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x7);
  	head[1] = dgram_size & 0xff;

  	memcpy(head + 2, &tag, sizeof(tag));

  	/* calc the nearest payload length(divided to 8) for first fragment
  	 * which fits into a IEEE802154_MTU
  	 */
  	frag_plen = round_down(IEEE802154_MTU - header_length -
  			       LOWPAN_FRAG1_HEAD_SIZE - lowpan_size -
  			       IEEE802154_MFR_SIZE, 8);

  	err = lowpan_fragment_xmit(skb, head, header_length,
  				   frag_plen + lowpan_size, 0,
  				   LOWPAN_DISPATCH_FRAG1);

  	if (err) {
  		pr_debug("%s unable to send FRAG1 packet (tag: %d)",
  			 __func__, tag);

  		goto exit;

  	}

  	offset = lowpan_size + frag_plen;
  	dgram_offset += frag_plen;

  
  	/* next fragment header */
  	head[0] &= ~LOWPAN_DISPATCH_FRAG1;
  	head[0] |= LOWPAN_DISPATCH_FRAGN;

  	frag_plen = round_down(IEEE802154_MTU - header_length -
  			       LOWPAN_FRAGN_HEAD_SIZE - IEEE802154_MFR_SIZE, 8);

  	while (payload_length - offset > 0) {

  		int len = frag_plen;

  		head[4] = dgram_offset >> 3;

  
  		if (payload_length - offset < len)
  			len = payload_length - offset;

  		err = lowpan_fragment_xmit(skb, head, header_length, len,
  					   offset, LOWPAN_DISPATCH_FRAGN);

  		if (err) {

  			pr_debug("%s unable to send a FRAGN packet. (tag: %d, offset: %d)
  ",
  				 __func__, tag, offset);

  			goto exit;

  		}

  		offset += len;

  		dgram_offset += len;

  	}

  exit:

  	return err;
  }

  static netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *dev)
  {

  	int err = -1;

  	pr_debug("package xmit
  ");

  
  	skb->dev = lowpan_dev_info(dev)->real_dev;
  	if (skb->dev == NULL) {

  		pr_debug("ERROR: no real wpan device found
  ");

  		goto error;
  	}

  	/* Send directly if less than the MTU minus the 2 checksum bytes. */
  	if (skb->len <= IEEE802154_MTU - IEEE802154_MFR_SIZE) {

  		err = dev_queue_xmit(skb);

  		goto out;
  	}

  	pr_debug("frame is too big, fragmentation is needed
  ");

  	err = lowpan_skb_fragmentation(skb, dev);

  error:
  	dev_kfree_skb(skb);
  out:

  	if (err)

  		pr_debug("ERROR: xmit failed
  ");

  	return (err < 0) ? NET_XMIT_DROP : err;

  }

  static struct wpan_phy *lowpan_get_phy(const struct net_device *dev)
  {
  	struct net_device *real_dev = lowpan_dev_info(dev)->real_dev;
  	return ieee802154_mlme_ops(real_dev)->get_phy(real_dev);
  }

  static __le16 lowpan_get_pan_id(const struct net_device *dev)

  {
  	struct net_device *real_dev = lowpan_dev_info(dev)->real_dev;
  	return ieee802154_mlme_ops(real_dev)->get_pan_id(real_dev);
  }

  static __le16 lowpan_get_short_addr(const struct net_device *dev)

  {
  	struct net_device *real_dev = lowpan_dev_info(dev)->real_dev;
  	return ieee802154_mlme_ops(real_dev)->get_short_addr(real_dev);
  }

  static u8 lowpan_get_dsn(const struct net_device *dev)
  {
  	struct net_device *real_dev = lowpan_dev_info(dev)->real_dev;
  	return ieee802154_mlme_ops(real_dev)->get_dsn(real_dev);
  }

  static struct header_ops lowpan_header_ops = {
  	.create	= lowpan_header_create,
  };

  static struct lock_class_key lowpan_tx_busylock;
  static struct lock_class_key lowpan_netdev_xmit_lock_key;
  
  static void lowpan_set_lockdep_class_one(struct net_device *dev,
  					 struct netdev_queue *txq,
  					 void *_unused)
  {
  	lockdep_set_class(&txq->_xmit_lock,
  			  &lowpan_netdev_xmit_lock_key);
  }
  
  
  static int lowpan_dev_init(struct net_device *dev)
  {
  	netdev_for_each_tx_queue(dev, lowpan_set_lockdep_class_one, NULL);
  	dev->qdisc_tx_busylock = &lowpan_tx_busylock;
  	return 0;
  }

  static const struct net_device_ops lowpan_netdev_ops = {

  	.ndo_init		= lowpan_dev_init,

  	.ndo_start_xmit		= lowpan_xmit,

  	.ndo_set_mac_address	= lowpan_set_address,

  };

  static struct ieee802154_mlme_ops lowpan_mlme = {
  	.get_pan_id = lowpan_get_pan_id,
  	.get_phy = lowpan_get_phy,
  	.get_short_addr = lowpan_get_short_addr,

  	.get_dsn = lowpan_get_dsn,

  };

  static void lowpan_setup(struct net_device *dev)
  {

  	dev->addr_len		= IEEE802154_ADDR_LEN;
  	memset(dev->broadcast, 0xff, IEEE802154_ADDR_LEN);
  	dev->type		= ARPHRD_IEEE802154;

  	/* Frame Control + Sequence Number + Address fields + Security Header */
  	dev->hard_header_len	= 2 + 1 + 20 + 14;
  	dev->needed_tailroom	= 2; /* FCS */
  	dev->mtu		= 1281;
  	dev->tx_queue_len	= 0;

  	dev->flags		= IFF_BROADCAST | IFF_MULTICAST;

  	dev->watchdog_timeo	= 0;
  
  	dev->netdev_ops		= &lowpan_netdev_ops;
  	dev->header_ops		= &lowpan_header_ops;

  	dev->ml_priv		= &lowpan_mlme;

  	dev->destructor		= free_netdev;

  }
  
  static int lowpan_validate(struct nlattr *tb[], struct nlattr *data[])
  {

  	if (tb[IFLA_ADDRESS]) {
  		if (nla_len(tb[IFLA_ADDRESS]) != IEEE802154_ADDR_LEN)
  			return -EINVAL;
  	}
  	return 0;
  }
  
  static int lowpan_rcv(struct sk_buff *skb, struct net_device *dev,
  	struct packet_type *pt, struct net_device *orig_dev)
  {

  	struct ieee802154_hdr hdr;

  	int ret;

  	skb = skb_share_check(skb, GFP_ATOMIC);
  	if (!skb)
  		goto drop;

  	if (!netif_running(dev))

  		goto drop_skb;

  
  	if (dev->type != ARPHRD_IEEE802154)

  		goto drop_skb;

  	if (ieee802154_hdr_peek_addrs(skb, &hdr) < 0)
  		goto drop_skb;

  	/* check that it's our buffer */

  	if (skb->data[0] == LOWPAN_DISPATCH_IPV6) {

  		skb->protocol = htons(ETH_P_IPV6);
  		skb->pkt_type = PACKET_HOST;

  
  		/* Pull off the 1-byte of 6lowpan header. */

  		skb_pull(skb, 1);

  		ret = lowpan_give_skb_to_devices(skb, NULL);

  		if (ret == NET_RX_DROP)
  			goto drop;

  	} else {
  		switch (skb->data[0] & 0xe0) {
  		case LOWPAN_DISPATCH_IPHC:	/* ipv6 datagram */

  			ret = process_data(skb, &hdr);

  			if (ret == NET_RX_DROP)
  				goto drop;
  			break;

  		case LOWPAN_DISPATCH_FRAG1:	/* first fragment header */

  			ret = lowpan_frag_rcv(skb, LOWPAN_DISPATCH_FRAG1);

  			if (ret == 1) {

  				ret = process_data(skb, &hdr);

  				if (ret == NET_RX_DROP)
  					goto drop;
  			}
  			break;

  		case LOWPAN_DISPATCH_FRAGN:	/* next fragments headers */

  			ret = lowpan_frag_rcv(skb, LOWPAN_DISPATCH_FRAGN);

  			if (ret == 1) {

  				ret = process_data(skb, &hdr);

  				if (ret == NET_RX_DROP)
  					goto drop;
  			}

  			break;
  		default:
  			break;
  		}

  	}

  
  	return NET_RX_SUCCESS;

  drop_skb:

  	kfree_skb(skb);

  drop:

  	return NET_RX_DROP;
  }
  
  static int lowpan_newlink(struct net *src_net, struct net_device *dev,
  			  struct nlattr *tb[], struct nlattr *data[])
  {
  	struct net_device *real_dev;
  	struct lowpan_dev_record *entry;

  	pr_debug("adding new link
  ");

  
  	if (!tb[IFLA_LINK])
  		return -EINVAL;
  	/* find and hold real wpan device */
  	real_dev = dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK]));
  	if (!real_dev)
  		return -ENODEV;

  	if (real_dev->type != ARPHRD_IEEE802154) {
  		dev_put(real_dev);

  		return -EINVAL;

  	}

  
  	lowpan_dev_info(dev)->real_dev = real_dev;
  	mutex_init(&lowpan_dev_info(dev)->dev_list_mtx);

  	entry = kzalloc(sizeof(*entry), GFP_KERNEL);

  	if (!entry) {
  		dev_put(real_dev);
  		lowpan_dev_info(dev)->real_dev = NULL;

  		return -ENOMEM;

  	}

  
  	entry->ldev = dev;

  	/* Set the lowpan harware address to the wpan hardware address. */
  	memcpy(dev->dev_addr, real_dev->dev_addr, IEEE802154_ADDR_LEN);

  	mutex_lock(&lowpan_dev_info(dev)->dev_list_mtx);
  	INIT_LIST_HEAD(&entry->list);
  	list_add_tail(&entry->list, &lowpan_devices);
  	mutex_unlock(&lowpan_dev_info(dev)->dev_list_mtx);
  
  	register_netdevice(dev);
  
  	return 0;
  }
  
  static void lowpan_dellink(struct net_device *dev, struct list_head *head)
  {
  	struct lowpan_dev_info *lowpan_dev = lowpan_dev_info(dev);
  	struct net_device *real_dev = lowpan_dev->real_dev;

  	struct lowpan_dev_record *entry, *tmp;

  
  	ASSERT_RTNL();
  
  	mutex_lock(&lowpan_dev_info(dev)->dev_list_mtx);

  	list_for_each_entry_safe(entry, tmp, &lowpan_devices, list) {

  		if (entry->ldev == dev) {
  			list_del(&entry->list);
  			kfree(entry);
  		}

  	}

  	mutex_unlock(&lowpan_dev_info(dev)->dev_list_mtx);
  
  	mutex_destroy(&lowpan_dev_info(dev)->dev_list_mtx);
  
  	unregister_netdevice_queue(dev, head);
  
  	dev_put(real_dev);
  }
  
  static struct rtnl_link_ops lowpan_link_ops __read_mostly = {
  	.kind		= "lowpan",
  	.priv_size	= sizeof(struct lowpan_dev_info),
  	.setup		= lowpan_setup,
  	.newlink	= lowpan_newlink,
  	.dellink	= lowpan_dellink,
  	.validate	= lowpan_validate,
  };
  
  static inline int __init lowpan_netlink_init(void)
  {
  	return rtnl_link_register(&lowpan_link_ops);
  }

  static inline void lowpan_netlink_fini(void)

  {
  	rtnl_link_unregister(&lowpan_link_ops);
  }

  static int lowpan_device_event(struct notifier_block *unused,

  			       unsigned long event, void *ptr)

  {

  	struct net_device *dev = netdev_notifier_info_to_dev(ptr);

  	LIST_HEAD(del_list);
  	struct lowpan_dev_record *entry, *tmp;
  
  	if (dev->type != ARPHRD_IEEE802154)
  		goto out;
  
  	if (event == NETDEV_UNREGISTER) {
  		list_for_each_entry_safe(entry, tmp, &lowpan_devices, list) {
  			if (lowpan_dev_info(entry->ldev)->real_dev == dev)
  				lowpan_dellink(entry->ldev, &del_list);
  		}
  
  		unregister_netdevice_many(&del_list);

  	}

  
  out:
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block lowpan_dev_notifier = {
  	.notifier_call = lowpan_device_event,
  };

  static struct packet_type lowpan_packet_type = {

  	.type = htons(ETH_P_IEEE802154),

  	.func = lowpan_rcv,
  };
  
  static int __init lowpan_init_module(void)
  {
  	int err = 0;

  	err = lowpan_net_frag_init();

  	if (err < 0)
  		goto out;

  	err = lowpan_netlink_init();
  	if (err < 0)
  		goto out_frag;

  	dev_add_pack(&lowpan_packet_type);

  
  	err = register_netdevice_notifier(&lowpan_dev_notifier);

  	if (err < 0)
  		goto out_pack;
  
  	return 0;
  
  out_pack:
  	dev_remove_pack(&lowpan_packet_type);
  	lowpan_netlink_fini();
  out_frag:
  	lowpan_net_frag_exit();

  out:
  	return err;
  }
  
  static void __exit lowpan_cleanup_module(void)
  {

  	lowpan_netlink_fini();
  
  	dev_remove_pack(&lowpan_packet_type);

  	lowpan_net_frag_exit();

  	unregister_netdevice_notifier(&lowpan_dev_notifier);

  }
  
  module_init(lowpan_init_module);
  module_exit(lowpan_cleanup_module);
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_RTNL_LINK("lowpan");