- check for bad sizes in hmac
- better error message from tlshand

Reference: /n/atom/patch/applied2013/secupd
Date: Wed Jun 19 16:26:49 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/libsec/port/hmac.c	Wed Jun 19 16:26:25 2013
+++ /sys/src/libsec/port/hmac.c	Wed Jun 19 16:26:25 2013
@@ -16,6 +16,10 @@
 
 	/* first time through */
 	if(s == nil || s->seeded == 0){
+		if(klen >= Hmacblksz){
+			print("klen too large: %lud", klen);
+			assert(0);
+		}
 		memset(pad, 0x36, Hmacblksz);
 		pad[Hmacblksz] = 0;
 		for(i = 0; i < klen; i++)
--- /sys/src/libsec/port/tlshand.c	Wed Jun 19 16:26:28 2013
+++ /sys/src/libsec/port/tlshand.c	Wed Jun 19 16:26:30 2013
@@ -921,7 +921,7 @@
 	if(act == AFlush){
 		sendp = sendbuf;
 		if(write(c->hand, sendbuf, p-sendbuf) < 0){
-			fprint(2, "write error: %r\n");
+			fprint(2, "tls flush: write(%d, %#p, %ld) error: %r\n", c->hand, sendbuf, p-sendbuf);
 			goto Err;
 		}
 	}