Add non-blocking support for connect (partly from patch #6860) plus many cleanups in socket & netconn API

src/include/lwip/api.h

@@ -61,6 +61,7 @@ extern "C" {
 #define NETCONNTYPE_GROUP(t)    (t&0xF0)
 #define NETCONNTYPE_DATAGRAM(t) (t&0xE0)
 
+/** Protocol family and type of the netconn */
 enum netconn_type {
   NETCONN_INVALID    = 0,
   /* NETCONN_TCP Group */
@@ -73,6 +74,8 @@ enum netconn_type {
   NETCONN_RAW        = 0x40
 };
 
+/** Current state of the netconn. Non-TCP netconns are always
+ * in state NETCONN_NONE! */
 enum netconn_state {
   NETCONN_NONE,
   NETCONN_WRITE,
@@ -81,6 +84,7 @@ enum netconn_state {
   NETCONN_CLOSE
 };
 
+/** Use to inform the callback function about changes */
 enum netconn_evt {
   NETCONN_EVT_RCVPLUS,
   NETCONN_EVT_RCVMINUS,
@@ -89,6 +93,7 @@ enum netconn_evt {
 };
 
 #if LWIP_IGMP
+/** Used for netconn_join_leave_group() */
 enum netconn_igmp {
   NETCONN_JOIN,
   NETCONN_LEAVE
@@ -152,10 +157,14 @@ struct netconn {
 #if LWIP_TCPIP_CORE_LOCKING
   /** TCP: when data passed to netconn_write doesn't fit into the send buffer,
       this temporarily stores whether to wake up the original application task
-      if data couldn't be sent in the first try. */
+      if data couldn't be sent in the first try. @todo: combine in 'flags' */
   u8_t write_delayed;
 #endif /* LWIP_TCPIP_CORE_LOCKING */
 #endif /* LWIP_TCP */
+  /** Should this netconn avoid blocking? @todo: combine in 'flags' */
+  u8_t non_blocking;
+  /** Was the last connect action a non-blocking one? @todo: combine in 'flags' */
+  u8_t in_non_blocking_connect;
   /** A callback function that is informed about events for this netconn */
   netconn_callback callback;
 };

src/include/lwip/err.h

@@ -54,24 +54,22 @@ typedef LWIP_ERR_T err_t;
 #define ERR_BUF        -2    /* Buffer error.            */
 #define ERR_TIMEOUT    -3    /* Timeout.                 */
 #define ERR_RTE        -4    /* Routing problem.         */
+#define ERR_INPROGRESS -5    /* Operation in progress    */
+#define ERR_VAL        -6    /* Illegal value.           */
 
-#define ERR_IS_FATAL(e) ((e) < ERR_RTE)
+#define ERR_IS_FATAL(e) ((e) < ERR_VAL)
 
-#define ERR_ABRT       -5    /* Connection aborted.      */
-#define ERR_RST        -6    /* Connection reset.        */
-#define ERR_CLSD       -7    /* Connection closed.       */
-#define ERR_CONN       -8    /* Not connected.           */
+#define ERR_ABRT       -7    /* Connection aborted.      */
+#define ERR_RST        -8    /* Connection reset.        */
+#define ERR_CLSD       -9    /* Connection closed.       */
+#define ERR_CONN       -10   /* Not connected.           */
 
-#define ERR_VAL        -9    /* Illegal value.           */
+#define ERR_ARG        -11   /* Illegal argument.        */
 
-#define ERR_ARG        -10   /* Illegal argument.        */
+#define ERR_USE        -12   /* Address in use.          */
 
-#define ERR_USE        -11   /* Address in use.          */
-
-#define ERR_IF         -12   /* Low-level netif error    */
-#define ERR_ISCONN     -13   /* Already connected.       */
-
-#define ERR_INPROGRESS -14   /* Operation in progress    */
+#define ERR_IF         -13   /* Low-level netif error    */
+#define ERR_ISCONN     -14   /* Already connected.       */
 
 
 #ifdef LWIP_DEBUG

src/include/lwip/sockets.h

@@ -262,10 +262,6 @@ typedef struct ip_mreq {
 #define SIOCATMARK  _IOR('s',  7, unsigned long)  /* at oob mark? */
 #endif
 
-/* Socket flags: */
-#ifndef O_NONBLOCK
-#define O_NONBLOCK    04000U
-#endif
 
 /* FD_SET used for lwip_select */
 #ifndef FD_SET