/*
   * Michael MIC implementation - optimized for TKIP MIC operations
   * Copyright 2002-2003, Instant802 Networks, Inc.
   *
   * 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.
   */

  #include <linux/types.h>

  #include <linux/bitops.h>

  #include <linux/ieee80211.h>

  #include <asm/unaligned.h>

  
  #include "michael.h"

  static void michael_block(struct michael_mic_ctx *mctx, u32 val)
  {
  	mctx->l ^= val;
  	mctx->r ^= rol32(mctx->l, 17);
  	mctx->l += mctx->r;
  	mctx->r ^= ((mctx->l & 0xff00ff00) >> 8) |
  		   ((mctx->l & 0x00ff00ff) << 8);
  	mctx->l += mctx->r;
  	mctx->r ^= rol32(mctx->l, 3);
  	mctx->l += mctx->r;
  	mctx->r ^= ror32(mctx->l, 2);
  	mctx->l += mctx->r;
  }

  static void michael_mic_hdr(struct michael_mic_ctx *mctx, const u8 *key,
  			    struct ieee80211_hdr *hdr)

  {

  	u8 *da, *sa, tid;
  
  	da = ieee80211_get_DA(hdr);
  	sa = ieee80211_get_SA(hdr);
  	if (ieee80211_is_data_qos(hdr->frame_control))
  		tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
  	else
  		tid = 0;

  	mctx->l = get_unaligned_le32(key);
  	mctx->r = get_unaligned_le32(key + 4);
  
  	/*
  	 * A pseudo header (DA, SA, Priority, 0, 0, 0) is used in Michael MIC
  	 * calculation, but it is _not_ transmitted
  	 */
  	michael_block(mctx, get_unaligned_le32(da));
  	michael_block(mctx, get_unaligned_le16(&da[4]) |
  			    (get_unaligned_le16(sa) << 16));
  	michael_block(mctx, get_unaligned_le32(&sa[2]));

  	michael_block(mctx, tid);

  }

  void michael_mic(const u8 *key, struct ieee80211_hdr *hdr,

  		 const u8 *data, size_t data_len, u8 *mic)

  {

  	u32 val;

  	size_t block, blocks, left;

  	struct michael_mic_ctx mctx;

  	michael_mic_hdr(&mctx, key, hdr);

  
  	/* Real data */
  	blocks = data_len / 4;
  	left = data_len % 4;

  	for (block = 0; block < blocks; block++)
  		michael_block(&mctx, get_unaligned_le32(&data[block * 4]));

  
  	/* Partial block of 0..3 bytes and padding: 0x5a + 4..7 zeros to make
  	 * total length a multiple of 4. */
  	val = 0x5a;
  	while (left > 0) {
  		val <<= 8;
  		left--;
  		val |= data[blocks * 4 + left];
  	}

  	michael_block(&mctx, val);
  	michael_block(&mctx, 0);
  
  	put_unaligned_le32(mctx.l, mic);
  	put_unaligned_le32(mctx.r, mic + 4);

  }