Add nsapi types for IP TOS and fix opt length check

Author: balajicyp

connectivity/lwipstack/source/LWIPStack.cpp

@@ -665,7 +665,7 @@ nsapi_error_t LWIP::setsockopt(nsapi_socket_t handle, int level, int optname, co
         }
 
         case NSAPI_IPTOS:
-            if (optlen != sizeof(int)) {
+            if (optlen != sizeof(u8_t)) {
                 return NSAPI_ERROR_UNSUPPORTED;
             }
             s->conn->pcb.ip->tos = (u8_t)(*(const int *)optval);

connectivity/netsocket/include/netsocket/nsapi_types.h

@@ -27,6 +27,50 @@ extern "C" {
 #endif
 
 
+/*
+ * The Type of Service provides an indication of the abstract
+ * parameters of the quality of service desired.  These parameters are
+ * to be used to guide the selection of the actual service parameters
+ * when transmitting a datagram through a particular network.  Several
+ * networks offer service precedence, which somehow treats high
+ * precedence traffic as more important than other traffic (generally
+ * by accepting only traffic above a certain precedence at time of high
+ * load).  The major choice is a three way tradeoff between low-delay,
+ * high-reliability, and high-throughput.
+ * The use of the Delay, Throughput, and Reliability indications may
+ * increase the cost (in some sense) of the service.  In many networks
+ * better performance for one of these parameters is coupled with worse
+ * performance on another.  Except for very unusual cases at most two
+ * of these three indications should be set.
+ */
+#define NSAPI_IPTOS_TOS_MASK          0x1E
+#define NSAPI_IPTOS_TOS(tos)          ((tos) & IPTOS_TOS_MASK)
+#define NSAPI_IPTOS_LOWDELAY          0x10
+#define NSAPI_IPTOS_THROUGHPUT        0x08
+#define NSAPI_IPTOS_RELIABILITY       0x04
+#define NSAPI_IPTOS_LOWCOST           0x02
+#define NSAPI_IPTOS_MINCOST           IPTOS_LOWCOST
+
+/*
+ * The Network Control precedence designation is intended to be used
+ * within a network only.  The actual use and control of that
+ * designation is up to each network. The Internetwork Control
+ * designation is intended for use by gateway control originators only.
+ * If the actual use of these precedence designations is of concern to
+ * a particular network, it is the responsibility of that network to
+ * control the access to, and use of, those precedence designations.
+ */
+#define NSAPI_IPTOS_PREC_MASK                 0xe0
+#define NSAPI_IPTOS_PREC(tos)                ((tos) & IPTOS_PREC_MASK)
+#define NSAPI_IPTOS_PREC_NETCONTROL           0xe0
+#define NSAPI_IPTOS_PREC_INTERNETCONTROL      0xc0
+#define NSAPI_IPTOS_PREC_CRITIC_ECP           0xa0
+#define NSAPI_IPTOS_PREC_FLASHOVERRIDE        0x80
+#define NSAPI_IPTOS_PREC_FLASH                0x60
+#define NSAPI_IPTOS_PREC_IMMEDIATE            0x40
+#define NSAPI_IPTOS_PREC_PRIORITY             0x20
+#define NSAPI_IPTOS_PREC_ROUTINE              0x00
+
 /** Enum of standardized error codes
  *
  *  Valid error codes have negative values and may