For AT firmware >= 1.7.0 - handle incoming data as OOB

When trying to pull data from the ESP8266 handle it as OOB to prevent
timeouts.

Author: Veijo Pesonen

ESP8266/ESP8266.cpp

@@ -73,10 +73,15 @@ ESP8266::ESP8266(PinName tx, PinName rx, bool debug, PinName rts, PinName cts)
     //https://github.com/esp8266/Arduino/blob/4897e0006b5b0123a2fa31f67b14a3fff65ce561/doc/faq/a02-my-esp-crashes.md#watchdog
     _parser.oob("Soft WDT reset", callback(this, &ESP8266::_oob_watchdog_reset));
     _parser.oob("busy ", callback(this, &ESP8266::_oob_busy));
+    // NOTE: documentation v3.0 says '+CIPRECVDATA:<data_len>,' but it's not how the FW responds...
+    _parser.oob("+CIPRECVDATA,", callback(this, &ESP8266::_oob_tcp_data_hdlr));
 
     for (int i = 0; i < SOCKET_COUNT; i++) {
         _sock_i[i].open = false;
         _sock_i[i].proto = NSAPI_UDP;
+        _sock_i[i].tcp_data = NULL;
+        _sock_i[i].tcp_data_avbl = 0;
+        _sock_i[i].tcp_data_rcvd = 0;
     }
 }
 
@@ -552,16 +557,12 @@ void ESP8266::_oob_packet_hdlr()
     if (!_parser.recv(",%d,", &id)) {
         return;
     }
-    // In passive mode amount not used...
-    if (_tcp_passive
-            && _sock_i[id].open == true
-            && _sock_i[id].proto == NSAPI_TCP) {
-        if (!_parser.recv("%d\n", &amount)) {
-            MBED_ERROR(MBED_MAKE_ERROR(MBED_MODULE_DRIVER, MBED_ERROR_CODE_ENODATA), \
-                       "ESP8266::_packet_handler(): Data length missing");
+
+    if(_tcp_passive && _sock_i[id].open == true && _sock_i[id].proto == NSAPI_TCP) {
+        if (_parser.recv("%d\n", &amount)) {
+            _sock_i[id].tcp_data_avbl = amount; // Not used but stored for the sake of visibility
         }
         return;
-        // Amount required in active mode
     } else if (!_parser.recv("%d:", &amount)) {
         return;
     }
@@ -614,41 +615,27 @@ void ESP8266::bg_process_oob(uint32_t timeout, bool all)
 
 int32_t ESP8266::_recv_tcp_passive(int id, void *data, uint32_t amount, uint32_t timeout)
 {
-    int32_t len;
-    int32_t ret = (int32_t)NSAPI_ERROR_WOULD_BLOCK;
+    int32_t ret;
 
     _smutex.lock();
 
-    // No flow control, drain the USART receive register ASAP to avoid data overrun
-    if (_serial_rts == NC) {
-        _process_oob(timeout, true);
-    }
+    _sock_i[id].tcp_data = (char*)data;
+    _sock_i[id].tcp_data_rcvd = NSAPI_ERROR_WOULD_BLOCK;
+    _sock_active_id = id;
 
-    // NOTE: documentation v3.0 says '+CIPRECVDATA:<data_len>,' but it's not how the FW responds...
     bool done = _parser.send("AT+CIPRECVDATA=%d,%lu", id, amount)
-                && _parser.recv("+CIPRECVDATA,%ld:", &len)
-                && _parser.read((char *)data, len)
                 && _parser.recv("OK\n");
 
-    if (done) {
-        _smutex.unlock();
-        return len;
-    }
+    (void)done;
+    _sock_i[id].tcp_data = NULL;
+    _sock_active_id = -1;
 
-    // Socket closed, doesn't mean there couldn't be data left
-    if (!_sock_i[id].open) {
-        done = _parser.send("AT+CIPRECVDATA=%d,%lu", id, amount)
-               && _parser.recv("+CIPRECVDATA,%ld:", &len)
-               && _parser.read((char *)data, len)
-               && _parser.recv("OK\n");
+    ret = _sock_i[id].tcp_data_rcvd;
 
-        ret = done ? len : 0;
+    if (!_sock_i[id].open && ret == NSAPI_ERROR_WOULD_BLOCK) {
+        ret = 0;
     }
 
-    // Flow control, read from USART receive register only when no more data is buffered, and as little as possible
-    if (_serial_rts != NC) {
-        _process_oob(timeout, false);
-    }
     _smutex.unlock();
     return ret;
 }
@@ -775,6 +762,13 @@ void ESP8266::_clear_socket_packets(int id)
             p = &(*p)->next;
         }
     }
+    if (id < 5) {
+        _sock_i[id].tcp_data_avbl = 0;
+    } else {
+        for (int id = 0; id < 5; id++) {
+            _sock_i[id].tcp_data_avbl = 0;
+        }
+    }
 }
 
 bool ESP8266::close(int id)
@@ -879,6 +873,23 @@ void ESP8266::_oob_busy()
     _busy = true;
 }
 
+void ESP8266::_oob_tcp_data_hdlr()
+{
+    int32_t len;
+
+    MBED_ASSERT(_sock_active_id >= 0 && _sock_active_id < 5);
+
+    if (!_parser.recv("%ld:", &len)) {
+        return;
+    }
+
+    if (!_parser.read(_sock_i[_sock_active_id].tcp_data, len)) {
+        return;
+    }
+
+    _sock_i[_sock_active_id].tcp_data_rcvd = len;
+}
+
 void ESP8266::_oob_connect_err()
 {
     _fail = false;

ESP8266/ESP8266.h

@@ -393,6 +393,7 @@ class ESP8266 {
         // data follows
     } *_packets, * *_packets_end;
     void _clear_socket_packets(int id);
+    int _sock_active_id;
 
     // Memory statistics
     size_t _heap_usage; // (Socket data buffer usage)
@@ -414,6 +415,7 @@ class ESP8266 {
     void _oob_socket_close_err();
     void _oob_watchdog_reset();
     void _oob_busy();
+    void _oob_tcp_data_hdlr();
 
     // OOB state variables
     int _connect_error;
@@ -433,6 +435,9 @@ class ESP8266 {
     struct _sock_info {
         bool open;
         nsapi_protocol_t proto;
+        char *tcp_data;
+        int32_t tcp_data_avbl; // Data waiting on modem
+        int32_t tcp_data_rcvd;
     };
     struct _sock_info _sock_i[SOCKET_COUNT];