fixed default value of TCP_SND_BUF to not violate the sanity checks in init.c

CHANGELOG

@@ -61,6 +61,10 @@ HISTORY
 
  ++ Bugfixes:
 
+  2011-09-21: Simon Goldschmidt
+  * opt.h: fixed default value of TCP_SND_BUF to not violate the sanity checks
+    in init.c
+
   2011-09-20: Simon Goldschmidt
   * timers.c: fixed bug #34337 (possible NULL pointer in sys_check_timeouts)
 

src/include/lwip/opt.h

@@ -968,10 +968,11 @@
 
 
 /**
- * TCP_SND_BUF: TCP sender buffer space (bytes). 
+ * TCP_SND_BUF: TCP sender buffer space (bytes).
+ * To achieve good performance, this should be at least 2 * TCP_MSS.
  */
 #ifndef TCP_SND_BUF
-#define TCP_SND_BUF                     256
+#define TCP_SND_BUF                     (2 * TCP_MSS)
 #endif
 
 /**
@@ -1434,7 +1435,8 @@
 #endif
 
 /**
- * LWIP_SO_RCVTIMEO==1: Enable SO_RCVTIMEO processing.
+ * LWIP_SO_RCVTIMEO==1: Enable receive timeout for sockets/netconns and
+ * SO_RCVTIMEO processing.
  */
 #ifndef LWIP_SO_RCVTIMEO
 #define LWIP_SO_RCVTIMEO                0