lib80211: Introduce TKIP_HDR_LEN define for code clarity

Introduce TKIP_HDR_LEN define for code clarity (in the same way as CCMP_HDR_LEN).

Also odd len variable (not used) dropped from lib80211_tkip_hdr().

---

Found few more candidates for TKIP_HDR_LEN usage comparing to prev. patch.

b/net/wireless/lib80211_crypt_tkip.c
index c362873..8cbdb32 100644

@@ -36,6 +36,8 @@ MODULE_AUTHOR("Jouni Malinen");
 MODULE_DESCRIPTION("lib80211 crypt: TKIP");
 MODULE_LICENSE("GPL");
 
+#define TKIP_HDR_LEN 8
+
 struct lib80211_tkip_data {
 #define TKIP_KEY_LEN 32
 	u8 key[TKIP_KEY_LEN];

@@ -314,13 +316,12 @@ static int lib80211_tkip_hdr(struct sk_buff *skb,

int hdr_len,
u8 * rc4key, int keylen, void *priv)
{
struct lib80211_tkip_data *tkey = priv;
- int len;
u8 *pos;
struct ieee80211_hdr *hdr;

hdr = (struct ieee80211_hdr *)skb->data;

- if (skb_headroom(skb) < 8 || skb->len < hdr_len)
+ if (skb_headroom(skb) < TKIP_HDR_LEN || skb->len < hdr_len)
return -1;

if (rc4key == NULL || keylen < 16)
@@ -333,9 +334,8 @@ static int lib80211_tkip_hdr(struct sk_buff *skb, int hdr_len,
}
tkip_mixing_phase2(rc4key, tkey->key, tkey->tx_ttak, tkey->tx_iv16);

- len = skb->len - hdr_len;
- pos = skb_push(skb, 8);
- memmove(pos, pos + 8, hdr_len);
+ pos = skb_push(skb, TKIP_HDR_LEN);
+ memmove(pos, pos + TKIP_HDR_LEN, hdr_len);
pos += hdr_len;

*pos++ = *rc4key;
@@ -353,7 +353,7 @@ static int lib80211_tkip_hdr(struct sk_buff *skb, int hdr_len,
tkey->tx_iv32++;
}

- return 8;
+ return TKIP_HDR_LEN;
}

static int lib80211_tkip_encrypt(struct sk_buff *skb, int hdr_len, void
*priv)
@@ -434,7 +433,7 @@ static int lib80211_tkip_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
return -1;
}

- if (skb->len < hdr_len + 8 + 4)
+ if (skb->len < hdr_len + TKIP_HDR_LEN + 4)
return -1;

pos = skb->data + hdr_len;
@@ -462,7 +461,7 @@ static int lib80211_tkip_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
}
iv16 = (pos[0] << 8) | pos[2];
iv32 = pos[4] | (pos[5] << 8) | (pos[6] << 16) | (pos[7] << 24);
- pos += 8;
+ pos += TKIP_HDR_LEN;

if (tkip_replay_check(iv32, iv16, tkey->rx_iv32, tkey->rx_iv16)) {
#ifdef CONFIG_LIB80211_DEBUG
@@ -523,8 +522,8 @@ static int lib80211_tkip_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
tkey->rx_iv16_new = iv16;

/* Remove IV and ICV */
- memmove(skb->data + 8, skb->data, hdr_len);
- skb_pull(skb, 8);
+ memmove(skb->data + TKIP_HDR_LEN, skb->data, hdr_len);
+ skb_pull(skb, TKIP_HDR_LEN);
skb_trim(skb, skb->len - 4);

return keyidx;