Fix socket state freshness and data availability

When opening TCP and UDP sockets there is a check to see whether
the socket is already in use or not. Because OOB messages are not
handled immediately there might be a mismatch between the stored
state and the actual state. This change processes any outstanding
OOB messages before opening the socket.

Similarly, when receiving data passively there is an internal
variable for keeping track of available data on the wifi modem.
This change processes any outstanding OOB messages before
receiving data.

Author: Marcus Chang

ESP8266/ESP8266.cpp

@@ -427,12 +427,16 @@ nsapi_error_t ESP8266::open_udp(int id, const char *addr, int port, int local_po
     static const char *type = "UDP";
     bool done = false;
 
+    _smutex.lock();
+
+    // process OOB so that _sock_i reflects the correct state of the socket
+    _process_oob(ESP8266_SEND_TIMEOUT, true);
+
     if (id >= SOCKET_COUNT || _sock_i[id].open) {
+        _smutex.unlock();
         return NSAPI_ERROR_PARAMETER;
     }
 
-    _smutex.lock();
-
     for (int i = 0; i < 2; i++) {
         if (local_port) {
             done = _parser.send("AT+CIPSTART=%d,\"%s\",\"%s\",%d,%d", id, type, addr, port, local_port);
@@ -477,12 +481,16 @@ nsapi_error_t ESP8266::open_tcp(int id, const char *addr, int port, int keepaliv
     static const char *type = "TCP";
     bool done = false;
 
+    _smutex.lock();
+
+    // process OOB so that _sock_i reflects the correct state of the socket
+    _process_oob(ESP8266_SEND_TIMEOUT, true);
+
     if (id >= SOCKET_COUNT || _sock_i[id].open) {
+        _smutex.unlock();
         return NSAPI_ERROR_PARAMETER;
     }
 
-    _smutex.lock();
-
     for (int i = 0; i < 2; i++) {
         if (keepalive) {
             done = _parser.send("AT+CIPSTART=%d,\"%s\",\"%s\",%d,%d", id, type, addr, port, keepalive);
@@ -655,6 +663,15 @@ int32_t ESP8266::_recv_tcp_passive(int id, void *data, uint32_t amount, uint32_t
         _sock_i[id].tcp_data = NULL;
         _sock_active_id = -1;
 
+        // update internal variable tcp_data_avbl to reflect the remaining data
+        if (_sock_i[id].tcp_data_rcvd > 0) {
+            if (_sock_i[id].tcp_data_avbl > _sock_i[id].tcp_data_rcvd) {
+                _sock_i[id].tcp_data_avbl -= _sock_i[id].tcp_data_rcvd;
+            } else {
+                _sock_i[id].tcp_data_avbl = 0;
+            }
+        }
+
         ret = _sock_i[id].tcp_data_rcvd;
     }