From abe463b931338e77095586052b66daade0428c95 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Mon, 6 Aug 2018 23:13:23 +0200
Subject: wifi: lilu dallas multirate

now handle the supported rates element properly, only
providing the intersecting set of rates that the bss
advertises and what the driver supports, putting the
basic rates first.

also avoid using usupported rates.
---
 sys/src/9/port/wifi.c | 83 +++++++++++++++++++++++++++++++++++++--------------
 sys/src/9/port/wifi.h |  3 ++
 2 files changed, 64 insertions(+), 22 deletions(-)

diff --git a/sys/src/9/port/wifi.c b/sys/src/9/port/wifi.c
index 67fa5fc46..10b5417a2 100644
--- a/sys/src/9/port/wifi.c
+++ b/sys/src/9/port/wifi.c
@@ -173,7 +173,7 @@ wifitx(Wifi *wifi, Wnode *wn, Block *b)
 		uchar *a, *p;
 
 		for(a = wn->maxrate, p = wifi->rates; *p; p++){
-			if(*p < *a && *p > *wn->actrate)
+			if(*p < *a && *p > *wn->actrate && (wn->validrates & (1UL << p-wifi->rates)) != 0)
 				a = p;
 		}
 		wn->actrate = a;
@@ -229,7 +229,7 @@ wifitxfail(Wifi *wifi, Block *b)
 		uchar *a, *p;
 
 		for(a = wn->minrate, p = wifi->rates; *p; p++){
-			if(*p > *a && *p < *wn->actrate)
+			if(*p > *a && *p < *wn->actrate && (wn->validrates & (1UL << p-wifi->rates)) != 0)
 				a = p;
 		}
 		wn->actrate = a;
@@ -237,25 +237,59 @@ wifitxfail(Wifi *wifi, Block *b)
 }
 
 static uchar*
-putrates(uchar *p, uchar *rates)
+putrates(uchar *p, uchar *rates, ulong valid, ulong basic)
 {
-	int n, m;
+	int n, i, j;
+
+	valid |= basic;
+
+	for(i = n = 0; i < 32 && rates[i] != 0; i++)
+		if(valid & (1UL<<i))
+			n++;
+
+	valid &= ~basic;
+
+	if(n > 0){
+		/* supported rates */
+		*p++ = 1;
+		*p++ = n;
+		for(i = j = 0; j < n; i++){
+			if(basic & (1UL<<i)){
+				*p++ = rates[i] | 0x80;
+				j++;
+			}
+		}
+		for(i = 0; j < n; i++){
+			if(valid & (1UL<<i)){
+				*p++ = rates[i] & 0x7f;
+				j++;
+			}
+		}
+	}
+
+	if(n > 8){
+		/* truncate supported rates element */
+		p -= n;
+		p[-1] = 8;
+		p += 8;
 
-	n = m = strlen((char*)rates);
-	if(n > 8)
-		n = 8;
-	/* supported rates */
-	*p++ = 1;
-	*p++ = n;
-	memmove(p, rates, n);
-	p += n;
-	if(m > 8){
 		/* extended supported rates */
 		*p++ = 50;
-		*p++ = m;
-		memmove(p, rates, m);
-		p += m;
+		*p++ = n;
+		for(i = j = 0; j < n; i++){
+			if(basic & (1UL<<i)){
+				*p++ = rates[i] | 0x80;
+				j++;
+			}
+		}
+		for(i = 0; j < n; i++){
+			if(valid & (1UL<<i)){
+				*p++ = rates[i] & 0x7f;
+				j++;
+			}
+		}
 	}
+
 	return p;
 }
 
@@ -289,7 +323,7 @@ wifiprobe(Wifi *wifi, Wnode *wn)
 	memmove(p, wifi->essid, n);
 	p += n;
 
-	p = putrates(p, wifi->rates);
+	p = putrates(p, wifi->rates, wn->validrates, wn->basicrates);
 
 	*p++ = 3;	/* ds parameter set */
 	*p++ = 1;
@@ -363,7 +397,7 @@ sendassoc(Wifi *wifi, Wnode *bss)
 	memmove(p, bss->ssid, n);
 	p += n;
 
-	p = putrates(p, wifi->rates);
+	p = putrates(p, wifi->rates, bss->validrates, bss->basicrates);
 
 	n = bss->rsnelen;
 	if(n > 0){
@@ -454,12 +488,15 @@ recvbeacon(Wifi *wifi, Wnode *wn, uchar *d, int len)
 			break;
 		case 1:		/* supported rates */
 		case 50:	/* extended rates */
-			if(wn->actrate != nil || wifi->rates == nil)
-				break;	/* already set */
+			if(wifi->rates == nil)
+				break;
 			while(d < x){
-				t = *d++ | 0x80;
+				t = *d | 0x80;
 				for(p = wifi->rates; *p != 0; p++){
 					if(*p == t){
+						wn->validrates |= 1UL << p-wifi->rates;
+						if(*d & 0x80)
+							wn->basicrates |= 1UL << p-wifi->rates;
 						if(wn->minrate == nil || t < *wn->minrate)
 							wn->minrate = p;
 						if(wn->maxrate == nil || t > *wn->maxrate)
@@ -467,8 +504,10 @@ recvbeacon(Wifi *wifi, Wnode *wn, uchar *d, int len)
 						break;
 					}
 				}
-				wn->actrate = wn->maxrate;
+				d++;
 			}
+			if(wn->actrate == nil)
+				wn->actrate = wn->maxrate;
 			break;
 		case 3:		/* DSPARAMS */
 			if(d != x)
diff --git a/sys/src/9/port/wifi.h b/sys/src/9/port/wifi.h
index 3abf4d1b9..09fc5c01a 100644
--- a/sys/src/9/port/wifi.h
+++ b/sys/src/9/port/wifi.h
@@ -43,6 +43,9 @@ struct Wnode
 	uchar	*maxrate;
 	uchar	*actrate;
 
+	ulong	validrates;	/* bitmap on wifi->rates */
+	ulong	basicrates;
+
 	ulong	txcount;	/* statistics for rate adaption */
 	ulong	txerror;
 
-- 
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