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wifi: cleanup

cleanup wifiencrypt()/wifidecrypt() routines moving tkip
and ccmp in separate routines so we dont use less stack
space.

--- a/sys/src/9/pc/wifi.c

+++ b/sys/src/9/pc/wifi.c

@@ -664,54 +664,23 @@

 	return n;

 }

-static void tkipk2tk(uchar key[16], u16int tk[8]);

-static void tkipphase1(u32int tscu, uchar ta[Eaddrlen], u16int tk[8], u16int p1k[5]);

-static void tkipphase2(u16int tscl, u16int p1k[5], u16int tk[8], uchar rc4key[16]);

+static void tkipencrypt(Wkey *k, Wifipkt *w, Block *b, uvlong tsc);

+static int tkipdecrypt(Wkey *k, Wifipkt *w, Block *b, uvlong tsc);

+static void ccmpencrypt(Wkey *k, Wifipkt *w, Block *b, uvlong tsc);

+static int ccmpdecrypt(Wkey *k, Wifipkt *w, Block *b, uvlong tsc);

-typedef struct MICstate MICstate;

-struct MICstate

-{

-	u32int	l;

-	u32int	r;

-	u32int	m;

-	u32int	n;

-};

-

-static void micsetup(MICstate *s, uchar key[8]);

-static void micupdate(MICstate *s, uchar *data, ulong len);

-static void micfinish(MICstate *s, uchar mic[8]);

-

-static uchar pad4[4] = { 0x00, 0x00, 0x00, 0x00, };

-

-static int setupCCMP(Wkey *k, Wifipkt *w, uvlong tsc, uchar nonce[13], uchar auth[30], AESstate *as);

-

-void aesCCMencrypt(int L, int M, uchar *N /* N[15-L] */,

-	uchar *a /* a[la] */, int la,

-	uchar *m /* m[lm+M] */, int lm,

-	AESstate *s);

-int aesCCMdecrypt(int L, int M, uchar *N /* N[15-L] */,

-	uchar *a /* a[la] */, int la,

-	uchar *m /* m[lm+M] */, int lm,

-	AESstate *s);

-

 static Block*

 wifiencrypt(Wifi *, Wnode *wn, Block *b)

 {

-	uchar auth[32], seed[16];

-	u16int tk[8], p1k[5];

 	uvlong tsc;

-	ulong crc;

-	AESstate as;

-	RC4state rs;

-	MICstate ms;

-	Wifipkt *w;

 	int n, kid;

+	Wifipkt *w;

 	Wkey *k;

 	kid = 0;

 	k = &wn->txkey[kid];

 	if(k->cipher == 0)

-		goto pass;

+		return b;

 	n = wifihdrlen((Wifipkt*)b->rp);

@@ -735,30 +704,9 @@

 		b->rp[6] = tsc>>32;

 		b->rp[7] = tsc>>40;

 		b->rp += 8;

-

 		if(k->len != 32)

 			goto drop;

-		micsetup(&ms, k->key+24);

-		micupdate(&ms, dstaddr(w), Eaddrlen);

-		micupdate(&ms, srcaddr(w), Eaddrlen);

-		micupdate(&ms, pad4, 4);

-		micupdate(&ms, b->rp, BLEN(b));

-		micfinish(&ms, b->wp);

-		b->wp += 8;

-

-		crc = ethercrc(b->rp, BLEN(b));

-		crc = ~crc;

-		b->wp[0] = crc;

-		b->wp[1] = crc>>8;

-		b->wp[2] = crc>>16;

-		b->wp[3] = crc>>24;

-		b->wp += 4;

-

-		tkipk2tk(k->key, tk);

-		tkipphase1(tsc >> 16, w->a2, tk, p1k);

-		tkipphase2(tsc & 0xFFFF, p1k, tk, seed);

-		setupRC4state(&rs, seed, sizeof(seed));

-		rc4(&rs, b->rp, BLEN(b));

+		tkipencrypt(k, w, b, tsc);

 		break;

 	case CCMP:

 		b->rp[0] = tsc;

@@ -770,39 +718,27 @@

 		b->rp[6] = tsc>>32;

 		b->rp[7] = tsc>>40;

 		b->rp += 8;

-

 		if(k->len != 16)

 			goto drop;

-		aesCCMencrypt(2, 8, seed, auth, setupCCMP(k, w, tsc, seed, auth, &as),

-			b->rp, BLEN(b), &as);

-		b->wp += 8;

+		ccmpencrypt(k, w, b, tsc);

 		break;

 	default:

-		goto drop;

+	drop:

+		free(b);

+		return nil;

 	}

 	b->rp = (uchar*)w;

 	w->fc[1] |= 0x40;

-

-pass:

 	return b;

-drop:

-	free(b);

-	return nil;

 }

 static Block*

 wifidecrypt(Wifi *, Wnode *wn, Block *b)

 {

-	uchar auth[32], seed[16], mic[8];

-	u16int tk[8], p1k[5];

-	RC4state rs;

-	AESstate as;

-	MICstate ms;

 	uvlong tsc;

-	ulong crc;

-	Wifipkt *w;

 	int n, kid;

+	Wifipkt *w;

 	Wkey *k;

 	w = (Wifipkt*)b->rp;

@@ -830,32 +766,10 @@

 			(uvlong)b->rp[0]<<8 |

 			(uvlong)b->rp[2];

 		b->rp += 8;

-		if(tsc <= k->tsc || BLEN(b) < 8+4 || k->len != 32)

+		if(tsc <= k->tsc || k->len != 32)

 			goto drop;

-		tkipk2tk(k->key, tk);

-		tkipphase1(tsc >> 16, w->a2, tk, p1k);

-		tkipphase2(tsc & 0xFFFF, p1k, tk, seed);

-		setupRC4state(&rs, seed, sizeof(seed));

-		rc4(&rs, b->rp, BLEN(b));

-

-		b->wp -= 4;

-		crc =	(ulong)b->wp[0] |

-			(ulong)b->wp[1]<<8 |

-			(ulong)b->wp[2]<<16 |

-			(ulong)b->wp[3]<<24;

-		crc = ~crc;

-		if(ethercrc(b->rp, BLEN(b)) != crc)

+		if(tkipdecrypt(k, w, b, tsc) != 0)

 			goto drop;

-

-		b->wp -= 8;

-		micsetup(&ms, k->key+16);

-		micupdate(&ms, dstaddr(w), Eaddrlen);

-		micupdate(&ms, srcaddr(w), Eaddrlen);

-		micupdate(&ms, pad4, 4);

-		micupdate(&ms, b->rp, BLEN(b));

-		micfinish(&ms, mic);

-		if(memcmp(b->wp, mic, 8) != 0)

-			goto drop;

 		break;

 	case CCMP:

 		tsc =	(uvlong)b->rp[7]<<40 |

@@ -867,13 +781,13 @@

 		b->rp += 8;

 		if(tsc <= k->tsc || k->len != 16)

 			goto drop;

-		b->wp -= 8;

-		if(aesCCMdecrypt(2, 8, seed, auth, setupCCMP(k, w, tsc, seed, auth, &as),

-			b->rp, BLEN(b), &as) != 0)

+		if(ccmpdecrypt(k, w, b, tsc) != 0)

 			goto drop;

 		break;

 	default:

-		goto drop;

+	drop:

+		freeb(b);

+		return nil;

 	}

 	k->tsc = tsc;

@@ -882,9 +796,6 @@

 	w = (Wifipkt*)b->rp;

 	w->fc[1] &= ~0x40;

 	return b;

-drop:

-	freeb(b);

-	return nil;

 }

 static u16int Sbox[256] = {

@@ -1043,6 +954,14 @@

 	rc4key[15] = ppk[5] >> 8;

 }

+typedef struct MICstate MICstate;

+struct MICstate

+{

+	u32int	l;

+	u32int	r;

+	u32int	m;

+	u32int	n;

+};

 static void

 micsetup(MICstate *s, uchar key[8])

@@ -1107,6 +1026,78 @@

 	mic[7] = s->r>>24;

 }

+static uchar pad4[4] = { 0x00, 0x00, 0x00, 0x00, };

+

+static void

+tkipencrypt(Wkey *k, Wifipkt *w, Block *b, uvlong tsc)

+{

+	u16int tk[8], p1k[5];

+	uchar seed[16];

+	RC4state rs;

+	MICstate ms;

+	ulong crc;

+

+	micsetup(&ms, k->key+24);

+	micupdate(&ms, dstaddr(w), Eaddrlen);

+	micupdate(&ms, srcaddr(w), Eaddrlen);

+	micupdate(&ms, pad4, 4);

+	micupdate(&ms, b->rp, BLEN(b));

+	micfinish(&ms, b->wp);

+	b->wp += 8;

+

+	crc = ethercrc(b->rp, BLEN(b));

+	crc = ~crc;

+	b->wp[0] = crc;

+	b->wp[1] = crc>>8;

+	b->wp[2] = crc>>16;

+	b->wp[3] = crc>>24;

+	b->wp += 4;

+

+	tkipk2tk(k->key, tk);

+	tkipphase1(tsc >> 16, w->a2, tk, p1k);

+	tkipphase2(tsc & 0xFFFF, p1k, tk, seed);

+	setupRC4state(&rs, seed, sizeof(seed));

+	rc4(&rs, b->rp, BLEN(b));

+}

+

+static int

+tkipdecrypt(Wkey *k, Wifipkt *w, Block *b, uvlong tsc)

+{

+	uchar seed[16], mic[8];

+	u16int tk[8], p1k[5];

+	RC4state rs;

+	MICstate ms;

+	ulong crc;

+

+	if(BLEN(b) < 8+4)

+		return -1;

+

+	tkipk2tk(k->key, tk);

+	tkipphase1(tsc >> 16, w->a2, tk, p1k);

+	tkipphase2(tsc & 0xFFFF, p1k, tk, seed);

+	setupRC4state(&rs, seed, sizeof(seed));

+	rc4(&rs, b->rp, BLEN(b));

+

+	b->wp -= 4;

+	crc =	(ulong)b->wp[0] |

+		(ulong)b->wp[1]<<8 |

+		(ulong)b->wp[2]<<16 |

+		(ulong)b->wp[3]<<24;

+	crc = ~crc;

+	if(ethercrc(b->rp, BLEN(b)) != crc)

+		return -1;

+

+	b->wp -= 8;

+	micsetup(&ms, k->key+16);

+	micupdate(&ms, dstaddr(w), Eaddrlen);

+	micupdate(&ms, srcaddr(w), Eaddrlen);

+	micupdate(&ms, pad4, 4);

+	micupdate(&ms, b->rp, BLEN(b));

+	micfinish(&ms, mic);

+

+	return memcmp(b->wp, mic, 8) != 0;

+}

+

 static uchar*

 putbe(uchar *p, int L, uint v)

 {

@@ -1150,7 +1141,7 @@

 	return b;

 };

-void

+static void

 aesCCMencrypt(int L, int M, uchar *N /* N[15-L] */,

 	uchar *a /* a[la] */, int la,

 	uchar *m /* m[lm+M] */, int lm,

@@ -1189,7 +1180,7 @@

 	memmove(m, t, M);

 }

-int

+static int

 aesCCMdecrypt(int L, int M, uchar *N /* N[15-L] */,

 	uchar *a /* a[la] */, int la,

 	uchar *m /* m[lm+M] */, int lm,

@@ -1254,4 +1245,31 @@

 	*p++ = 0;

 	return p - auth;

+}

+

+static void

+ccmpencrypt(Wkey *k, Wifipkt *w, Block *b, uvlong tsc)

+{

+	uchar auth[32], nonce[13];

+	AESstate as;

+

+	aesCCMencrypt(2, 8, nonce, auth,

+		setupCCMP(k, w, tsc, nonce, auth, &as),

+		b->rp, BLEN(b), &as);

+	b->wp += 8;

+}

+

+static int

+ccmpdecrypt(Wkey *k, Wifipkt *w, Block *b, uvlong tsc)

+{

+	uchar auth[32], nonce[13];

+	AESstate as;

+

+	if(BLEN(b) < 8)

+		return -1;

+

+	b->wp -= 8;

+	return aesCCMdecrypt(2, 8, nonce, auth,

+		setupCCMP(k, w, tsc, nonce, auth, &as),

+		b->rp, BLEN(b), &as);

 }