/*
   * Copyright (C) 2007-2012 Siemens AG
   *
   * 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.
   *

   * Written by:
   * Pavel Smolenskiy <pavel.smolenskiy@gmail.com>
   * Maxim Gorbachyov <maxim.gorbachev@siemens.com>
   * Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
   * Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/netdevice.h>
  #include <linux/crc-ccitt.h>

  #include <asm/unaligned.h>

  
  #include <net/mac802154.h>
  #include <net/ieee802154_netdev.h>

  #include <net/nl802154.h>

  #include "ieee802154_i.h"

  static int ieee802154_deliver_skb(struct sk_buff *skb)

  {

  	skb->ip_summed = CHECKSUM_UNNECESSARY;

  	skb->protocol = htons(ETH_P_IEEE802154);

  	return netif_receive_skb(skb);
  }
  
  static int

  ieee802154_subif_frame(struct ieee802154_sub_if_data *sdata,
  		       struct sk_buff *skb, const struct ieee802154_hdr *hdr)

  {

  	struct wpan_dev *wpan_dev = &sdata->wpan_dev;

  	__le16 span, sshort;
  	int rc;
  
  	pr_debug("getting packet via slave interface %s
  ", sdata->dev->name);

  	span = wpan_dev->pan_id;
  	sshort = wpan_dev->short_addr;

  
  	switch (mac_cb(skb)->dest.mode) {
  	case IEEE802154_ADDR_NONE:
  		if (mac_cb(skb)->dest.mode != IEEE802154_ADDR_NONE)
  			/* FIXME: check if we are PAN coordinator */
  			skb->pkt_type = PACKET_OTHERHOST;
  		else
  			/* ACK comes with both addresses empty */
  			skb->pkt_type = PACKET_HOST;
  		break;
  	case IEEE802154_ADDR_LONG:
  		if (mac_cb(skb)->dest.pan_id != span &&
  		    mac_cb(skb)->dest.pan_id != cpu_to_le16(IEEE802154_PANID_BROADCAST))
  			skb->pkt_type = PACKET_OTHERHOST;

  		else if (mac_cb(skb)->dest.extended_addr == wpan_dev->extended_addr)

  			skb->pkt_type = PACKET_HOST;
  		else
  			skb->pkt_type = PACKET_OTHERHOST;
  		break;
  	case IEEE802154_ADDR_SHORT:
  		if (mac_cb(skb)->dest.pan_id != span &&
  		    mac_cb(skb)->dest.pan_id != cpu_to_le16(IEEE802154_PANID_BROADCAST))
  			skb->pkt_type = PACKET_OTHERHOST;
  		else if (mac_cb(skb)->dest.short_addr == sshort)
  			skb->pkt_type = PACKET_HOST;
  		else if (mac_cb(skb)->dest.short_addr ==
  			  cpu_to_le16(IEEE802154_ADDR_BROADCAST))
  			skb->pkt_type = PACKET_BROADCAST;
  		else
  			skb->pkt_type = PACKET_OTHERHOST;
  		break;
  	default:

  		pr_debug("invalid dest mode
  ");

  		goto fail;

  	}

  	skb->dev = sdata->dev;

  	/* TODO this should be moved after netif_receive_skb call, otherwise
  	 * wireshark will show a mac header with security fields and the
  	 * payload is already decrypted.
  	 */

  	rc = mac802154_llsec_decrypt(&sdata->sec, skb);
  	if (rc) {
  		pr_debug("decryption failed: %i
  ", rc);
  		goto fail;
  	}
  
  	sdata->dev->stats.rx_packets++;
  	sdata->dev->stats.rx_bytes += skb->len;
  
  	switch (mac_cb(skb)->type) {

  	case IEEE802154_FC_TYPE_BEACON:
  	case IEEE802154_FC_TYPE_ACK:
  	case IEEE802154_FC_TYPE_MAC_CMD:
  		goto fail;

  	case IEEE802154_FC_TYPE_DATA:

  		return ieee802154_deliver_skb(skb);

  	default:

  		pr_warn_ratelimited("ieee802154: bad frame received "
  				    "(type = %d)
  ", mac_cb(skb)->type);

  		goto fail;
  	}
  
  fail:
  	kfree_skb(skb);
  	return NET_RX_DROP;
  }

  static void
  ieee802154_print_addr(const char *name, const struct ieee802154_addr *addr)

  {
  	if (addr->mode == IEEE802154_ADDR_NONE)
  		pr_debug("%s not present
  ", name);
  
  	pr_debug("%s PAN ID: %04x
  ", name, le16_to_cpu(addr->pan_id));
  	if (addr->mode == IEEE802154_ADDR_SHORT) {
  		pr_debug("%s is short: %04x
  ", name,
  			 le16_to_cpu(addr->short_addr));
  	} else {
  		u64 hw = swab64((__force u64)addr->extended_addr);
  
  		pr_debug("%s is hardware: %8phC
  ", name, &hw);
  	}
  }

  static int
  ieee802154_parse_frame_start(struct sk_buff *skb, struct ieee802154_hdr *hdr)

  {
  	int hlen;
  	struct ieee802154_mac_cb *cb = mac_cb_init(skb);

  	skb_reset_mac_header(skb);

  	hlen = ieee802154_hdr_pull(skb, hdr);
  	if (hlen < 0)
  		return -EINVAL;
  
  	skb->mac_len = hlen;
  
  	pr_debug("fc: %04x dsn: %02x
  ", le16_to_cpup((__le16 *)&hdr->fc),
  		 hdr->seq);
  
  	cb->type = hdr->fc.type;
  	cb->ackreq = hdr->fc.ack_request;
  	cb->secen = hdr->fc.security_enabled;

  	ieee802154_print_addr("destination", &hdr->dest);
  	ieee802154_print_addr("source", &hdr->source);

  
  	cb->source = hdr->source;
  	cb->dest = hdr->dest;
  
  	if (hdr->fc.security_enabled) {
  		u64 key;
  
  		pr_debug("seclevel %i
  ", hdr->sec.level);
  
  		switch (hdr->sec.key_id_mode) {
  		case IEEE802154_SCF_KEY_IMPLICIT:
  			pr_debug("implicit key
  ");
  			break;
  
  		case IEEE802154_SCF_KEY_INDEX:
  			pr_debug("key %02x
  ", hdr->sec.key_id);
  			break;
  
  		case IEEE802154_SCF_KEY_SHORT_INDEX:
  			pr_debug("key %04x:%04x %02x
  ",
  				 le32_to_cpu(hdr->sec.short_src) >> 16,
  				 le32_to_cpu(hdr->sec.short_src) & 0xffff,
  				 hdr->sec.key_id);
  			break;
  
  		case IEEE802154_SCF_KEY_HW_INDEX:
  			key = swab64((__force u64)hdr->sec.extended_src);
  			pr_debug("key source %8phC %02x
  ", &key,
  				 hdr->sec.key_id);
  			break;
  		}
  	}
  
  	return 0;
  }
  
  static void

  __ieee802154_rx_handle_packet(struct ieee802154_local *local,
  			      struct sk_buff *skb)

  {
  	int ret;
  	struct ieee802154_sub_if_data *sdata;
  	struct ieee802154_hdr hdr;

  	ret = ieee802154_parse_frame_start(skb, &hdr);

  	if (ret) {
  		pr_debug("got invalid frame
  ");
  		kfree_skb(skb);
  		return;
  	}

  	list_for_each_entry_rcu(sdata, &local->interfaces, list) {

  		if (sdata->wpan_dev.iftype != NL802154_IFTYPE_NODE)
  			continue;
  
  		if (!ieee802154_sdata_running(sdata))

  			continue;

  		ieee802154_subif_frame(sdata, skb, &hdr);

  		skb = NULL;
  		break;
  	}

  	kfree_skb(skb);

  }

  static void

  ieee802154_monitors_rx(struct ieee802154_local *local, struct sk_buff *skb)

  {
  	struct sk_buff *skb2;
  	struct ieee802154_sub_if_data *sdata;

  	skb_reset_mac_header(skb);

  	skb->ip_summed = CHECKSUM_UNNECESSARY;

  	skb->pkt_type = PACKET_OTHERHOST;

  	skb->protocol = htons(ETH_P_IEEE802154);

  	list_for_each_entry_rcu(sdata, &local->interfaces, list) {

  		if (sdata->wpan_dev.iftype != NL802154_IFTYPE_MONITOR)

  			continue;
  
  		if (!ieee802154_sdata_running(sdata))

  			continue;
  
  		skb2 = skb_clone(skb, GFP_ATOMIC);

  		if (skb2) {
  			skb2->dev = sdata->dev;
  			ieee802154_deliver_skb(skb2);

  			sdata->dev->stats.rx_packets++;
  			sdata->dev->stats.rx_bytes += skb->len;
  		}

  	}

  }

  void ieee802154_rx(struct ieee802154_local *local, struct sk_buff *skb)

  {

  	u16 crc;

  	WARN_ON_ONCE(softirq_count() == 0);

  	if (local->suspended)
  		goto drop;

  	/* TODO: When a transceiver omits the checksum here, we
  	 * add an own calculated one. This is currently an ugly
  	 * solution because the monitor needs a crc here.
  	 */
  	if (local->hw.flags & IEEE802154_HW_RX_OMIT_CKSUM) {

  		crc = crc_ccitt(0, skb->data, skb->len);

  		put_unaligned_le16(crc, skb_put(skb, 2));

  	}

  	rcu_read_lock();

  	ieee802154_monitors_rx(local, skb);

  	/* Check if transceiver doesn't validate the checksum.
  	 * If not we validate the checksum here.
  	 */
  	if (local->hw.flags & IEEE802154_HW_RX_DROP_BAD_CKSUM) {
  		crc = crc_ccitt(0, skb->data, skb->len);
  		if (crc) {
  			rcu_read_unlock();

  			goto drop;

  		}
  	}

  	/* remove crc */
  	skb_trim(skb, skb->len - 2);

  	__ieee802154_rx_handle_packet(local, skb);

  	rcu_read_unlock();

  
  	return;
  drop:
  	kfree_skb(skb);

  }

  
  void

  ieee802154_rx_irqsafe(struct ieee802154_hw *hw, struct sk_buff *skb, u8 lqi)

  {

  	struct ieee802154_local *local = hw_to_local(hw);

  	mac_cb(skb)->lqi = lqi;
  	skb->pkt_type = IEEE802154_RX_MSG;
  	skb_queue_tail(&local->skb_queue, skb);
  	tasklet_schedule(&local->tasklet);

  }
  EXPORT_SYMBOL(ieee802154_rx_irqsafe);