/*
        Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
        <http://rt2x00.serialmonkey.com>

        This program is free software; you can redistribute it and/or modify
        it under the terms of the GNU General Public License as published by
        the Free Software Foundation; either version 2 of the License, or
        (at your option) any later version.

        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.

        You should have received a copy of the GNU General Public License
        along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

/*
        Module: rt2x00lib
        Abstract: rt2x00 crypto specific routines.
 */

#include <linux/kernel.h>
#include <linux/module.h>

#include "rt2x00.h"
#include "rt2x00lib.h"

enum cipher rt2x00crypto_key_to_cipher(struct ieee80211_key_conf *key)
{
        switch (key->cipher) {
        case WLAN_CIPHER_SUITE_WEP40:
                return CIPHER_WEP64;
        case WLAN_CIPHER_SUITE_WEP104:
                return CIPHER_WEP128;
        case WLAN_CIPHER_SUITE_TKIP:
                return CIPHER_TKIP;
        case WLAN_CIPHER_SUITE_CCMP:
                return CIPHER_AES;
        default:
                return CIPHER_NONE;
        }
}

void rt2x00crypto_create_tx_descriptor(struct rt2x00_dev *rt2x00dev,
                                       struct sk_buff *skb,
                                       struct txentry_desc *txdesc)
{
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
        struct ieee80211_key_conf *hw_key = tx_info->control.hw_key;

        if (!rt2x00_has_cap_hw_crypto(rt2x00dev) || !hw_key)
                return;

        __set_bit(ENTRY_TXD_ENCRYPT, &txdesc->flags);

        txdesc->cipher = rt2x00crypto_key_to_cipher(hw_key);

        if (hw_key->flags & IEEE80211_KEY_FLAG_PAIRWISE)
                __set_bit(ENTRY_TXD_ENCRYPT_PAIRWISE, &txdesc->flags);

        txdesc->key_idx = hw_key->hw_key_idx;
        txdesc->iv_offset = txdesc->header_length;
        txdesc->iv_len = hw_key->iv_len;

        if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
                __set_bit(ENTRY_TXD_ENCRYPT_IV, &txdesc->flags);

        if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC))
                __set_bit(ENTRY_TXD_ENCRYPT_MMIC, &txdesc->flags);
}

unsigned int rt2x00crypto_tx_overhead(struct rt2x00_dev *rt2x00dev,
                                      struct sk_buff *skb)
{
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
        struct ieee80211_key_conf *key = tx_info->control.hw_key;
        unsigned int overhead = 0;

        if (!rt2x00_has_cap_hw_crypto(rt2x00dev) || !key)
                return overhead;

        /*
         * Extend frame length to include IV/EIV/ICV/MMIC,
         * note that these lengths should only be added when
         * mac80211 does not generate it.
         */
        overhead += key->icv_len;

        if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
                overhead += key->iv_len;

        if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
                if (key->cipher == WLAN_CIPHER_SUITE_TKIP)
                        overhead += 8;
        }

        return overhead;
}

void rt2x00crypto_tx_copy_iv(struct sk_buff *skb, struct txentry_desc *txdesc)
{
        struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);

        if (unlikely(!txdesc->iv_len))
                return;

        /* Copy IV/EIV data */
        memcpy(skbdesc->iv, skb->data + txdesc->iv_offset, txdesc->iv_len);
}

void rt2x00crypto_tx_remove_iv(struct sk_buff *skb, struct txentry_desc *txdesc)
{
        struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);

        if (unlikely(!txdesc->iv_len))
                return;

        /* Copy IV/EIV data */
        memcpy(skbdesc->iv, skb->data + txdesc->iv_offset, txdesc->iv_len);

        /* Move ieee80211 header */
        memmove(skb->data + txdesc->iv_len, skb->data, txdesc->iv_offset);

        /* Pull buffer to correct size */
        skb_pull(skb, txdesc->iv_len);
        txdesc->length -= txdesc->iv_len;

        /* IV/EIV data has officially been stripped */
        skbdesc->flags |= SKBDESC_IV_STRIPPED;
}

void rt2x00crypto_tx_insert_iv(struct sk_buff *skb, unsigned int header_length)
{
        struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
        const unsigned int iv_len =
            ((!!(skbdesc->iv[0])) * 4) + ((!!(skbdesc->iv[1])) * 4);

        if (!(skbdesc->flags & SKBDESC_IV_STRIPPED))
                return;

        skb_push(skb, iv_len);

        /* Move ieee80211 header */
        memmove(skb->data, skb->data + iv_len, header_length);

        /* Copy IV/EIV data */
        memcpy(skb->data + header_length, skbdesc->iv, iv_len);

        /* IV/EIV data has returned into the frame */
        skbdesc->flags &= ~SKBDESC_IV_STRIPPED;
}

void rt2x00crypto_rx_insert_iv(struct sk_buff *skb,
                               unsigned int header_length,
                               struct rxdone_entry_desc *rxdesc)
{
        unsigned int payload_len = rxdesc->size - header_length;
        unsigned int align = ALIGN_SIZE(skb, header_length);
        unsigned int iv_len;
        unsigned int icv_len;
        unsigned int transfer = 0;

        /*
         * WEP64/WEP128: Provides IV & ICV
         * TKIP: Provides IV/EIV & ICV
         * AES: Provies IV/EIV & ICV
         */
        switch (rxdesc->cipher) {
        case CIPHER_WEP64:
        case CIPHER_WEP128:
                iv_len = 4;
                icv_len = 4;
                break;
        case CIPHER_TKIP:
                iv_len = 8;
                icv_len = 4;
                break;
        case CIPHER_AES:
                iv_len = 8;
                icv_len = 8;
                break;
        default:
                /* Unsupport type */
                return;
        }

        /*
         * Make room for new data. There are 2 possibilities
         * either the alignment is already present between
         * the 802.11 header and payload. In that case we
         * we have to move the header less then the iv_len
         * since we can use the already available l2pad bytes
         * for the iv data.
         * When the alignment must be added manually we must
         * move the header more then iv_len since we must
         * make room for the payload move as well.
         */
        if (rxdesc->dev_flags & RXDONE_L2PAD) {
                skb_push(skb, iv_len - align);
                skb_put(skb, icv_len);

                /* Move ieee80211 header */
                memmove(skb->data + transfer,
                        skb->data + transfer + (iv_len - align),
                        header_length);
                transfer += header_length;
        } else {
                skb_push(skb, iv_len + align);
                if (align < icv_len)
                        skb_put(skb, icv_len - align);
                else if (align > icv_len)
                        skb_trim(skb, rxdesc->size + iv_len + icv_len);

                /* Move ieee80211 header */
                memmove(skb->data + transfer,
                        skb->data + transfer + iv_len + align,
                        header_length);
                transfer += header_length;
        }

        /* Copy IV/EIV data */
        memcpy(skb->data + transfer, rxdesc->iv, iv_len);
        transfer += iv_len;

        /*
         * Move payload for alignment purposes. Note that
         * this is only needed when no l2 padding is present.
         */
        if (!(rxdesc->dev_flags & RXDONE_L2PAD)) {
                memmove(skb->data + transfer,
                        skb->data + transfer + align,
                        payload_len);
        }

        /*
         * NOTE: Always count the payload as transferred,
         * even when alignment was set to zero. This is required
         * for determining the correct offset for the ICV data.
         */
        transfer += payload_len;

        /*
         * Copy ICV data
         * AES appends 8 bytes, we can't fill the upper
         * 4 bytes, but mac80211 doesn't care about what
         * we provide here anyway and strips it immediately.
         */
        memcpy(skb->data + transfer, &rxdesc->icv, 4);
        transfer += icv_len;

        /* IV/EIV/ICV has been inserted into frame */
        rxdesc->size = transfer;
        rxdesc->flags &= ~RX_FLAG_IV_STRIPPED;
}