Cellular: Handling of TCP endpoint closed

Author: Ari Parkkila

features/cellular/framework/AT/AT_CellularContext.cpp

@@ -112,6 +112,8 @@ nsapi_error_t AT_CellularContext::connect()
     if (_is_connected) {
         return NSAPI_ERROR_IS_CONNECTED;
     }
+    call_network_cb(NSAPI_STATUS_CONNECTING);
+
     nsapi_error_t err = _device->attach_to_network();
     _cb_data.error = check_operation(err, OP_CONNECT);
 
@@ -130,6 +132,10 @@ nsapi_error_t AT_CellularContext::connect()
         }
     }
 
+    if (_cb_data.error == NSAPI_ERROR_ALREADY) {
+        return NSAPI_ERROR_OK;
+    }
+
     return _cb_data.error;
 }
 
@@ -543,8 +549,6 @@ nsapi_error_t AT_CellularContext::activate_context()
 
 void AT_CellularContext::do_connect()
 {
-    call_network_cb(NSAPI_STATUS_CONNECTING);
-
     if (!_is_context_active) {
         _cb_data.error = do_activate_context();
 #if !NSAPI_PPP_AVAILABLE
@@ -677,10 +681,11 @@ nsapi_error_t AT_CellularContext::disconnect()
         } else {
             deactivate_ip_context();
         }
+    } else {
+        call_network_cb(NSAPI_STATUS_DISCONNECTED);
     }
 
     _is_connected = false;
-    call_network_cb(NSAPI_STATUS_DISCONNECTED);
 
     return _at.unlock_return_error();
 }
@@ -736,11 +741,6 @@ void AT_CellularContext::deactivate_context()
         _at.write_int(_cid);
         _at.cmd_stop_read_resp();
     }
-
-    _at.clear_error();
-    _at.cmd_start("AT+CGATT=0");
-    _at.cmd_stop_read_resp();
-    _at.restore_at_timeout();
 }
 
 nsapi_error_t AT_CellularContext::get_apn_backoff_timer(int &backoff_timer)

features/cellular/framework/AT/AT_CellularStack.cpp

@@ -253,6 +253,19 @@ nsapi_size_or_error_t AT_CellularStack::socket_sendto(nsapi_socket_t handle, con
         return NSAPI_ERROR_DEVICE_ERROR;
     }
 
+    if (socket->closed && !socket->rx_avail) {
+        tr_info("sendto socket %d closed", socket->id);
+        return NSAPI_ERROR_NO_CONNECTION;
+    }
+
+    if (size == 0) {
+        if (socket->proto == NSAPI_UDP) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        } else if (socket->proto == NSAPI_TCP) {
+            return 0;
+        }
+    }
+
     nsapi_size_or_error_t ret_val = NSAPI_ERROR_OK;
 
     if (!socket->created) {
@@ -299,6 +312,11 @@ nsapi_size_or_error_t AT_CellularStack::socket_recvfrom(nsapi_socket_t handle, S
         return NSAPI_ERROR_DEVICE_ERROR;
     }
 
+    if (socket->closed) {
+        tr_info("recvfrom socket %d closed", socket->id);
+        return 0;
+    }
+
     nsapi_size_or_error_t ret_val = NSAPI_ERROR_OK;
 
     if (!socket->created) {
@@ -319,6 +337,11 @@ nsapi_size_or_error_t AT_CellularStack::socket_recvfrom(nsapi_socket_t handle, S
 
     _at.unlock();
 
+    if (socket->closed) {
+        tr_info("recvfrom socket %d closed", socket->id);
+        return 0;
+    }
+
     if (ret_val >= 0) {
         if (addr) {
             tr_info("Socket %d recv %d bytes from %s port %d", find_socket_index(socket), ret_val, addr->get_ip_address(), addr->get_port());
@@ -352,3 +375,18 @@ int AT_CellularStack::get_socket_index_by_port(uint16_t port)
     }
     return -1;
 }
+
+AT_CellularStack::CellularSocket *AT_CellularStack::find_socket(int sock_id)
+{
+    CellularSocket *sock = NULL;
+    for (int i = 0; i < _socket_count; i++) {
+        if (_socket[i] && _socket[i]->id == sock_id) {
+            sock = _socket[i];
+            break;
+        }
+    }
+    if (!sock) {
+        tr_error("Socket not found %d", sock_id);
+    }
+    return sock;
+}

features/cellular/framework/AT/AT_CellularStack.h

@@ -92,6 +92,7 @@ class AT_CellularStack : public NetworkStack, public AT_CellularBase {
             _cb(NULL),
             _data(NULL),
             created(false),
+            closed(false),
             started(false),
             tx_ready(false),
             rx_avail(false),
@@ -108,6 +109,7 @@ class AT_CellularStack : public NetworkStack, public AT_CellularBase {
         void (*_cb)(void *);
         void *_data;
         bool created; // socket has been created on modem stack
+        bool closed; // socket has been closed by a peer
         bool started; // socket has been opened on modem stack
         bool tx_ready; // socket is ready for sending on modem stack
         bool rx_avail; // socket has data for reading on modem stack
@@ -166,6 +168,14 @@ class AT_CellularStack : public NetworkStack, public AT_CellularBase {
     virtual nsapi_size_or_error_t socket_recvfrom_impl(CellularSocket *socket, SocketAddress *address,
                                                        void *buffer, nsapi_size_t size) = 0;
 
+    /**
+     *  Find the socket handle based on socket identifier
+     *
+     *  @param sock_id  Socket identifier
+     *  @return         Socket handle, NULL on error
+     */
+    CellularSocket *find_socket(int sock_id);
+
     // socket container
     CellularSocket **_socket;