/*
 * 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\n", 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\n");
                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\n", rc);
                goto fail;
        }

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

        switch (mac_cb(skb)->type) {
        case IEEE802154_FC_TYPE_DATA:
                return ieee802154_deliver_skb(skb);
        default:
                pr_warn("ieee802154: bad frame received (type = %d)\n",
                        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\n", name);

        pr_debug("%s PAN ID: %04x\n", name, le16_to_cpu(addr->pan_id));
        if (addr->mode == IEEE802154_ADDR_SHORT) {
                pr_debug("%s is short: %04x\n", name,
                         le16_to_cpu(addr->short_addr));
        } else {
                u64 hw = swab64((__force u64)addr->extended_addr);

                pr_debug("%s is hardware: %8phC\n", 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\n", 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\n", hdr->sec.level);

                switch (hdr->sec.key_id_mode) {
                case IEEE802154_SCF_KEY_IMPLICIT:
                        pr_debug("implicit key\n");
                        break;

                case IEEE802154_SCF_KEY_INDEX:
                        pr_debug("key %02x\n", hdr->sec.key_id);
                        break;

                case IEEE802154_SCF_KEY_SHORT_INDEX:
                        pr_debug("key %04x:%04x %02x\n",
                                 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\n", &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\n");
                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);