Cellular: Use more specific error codes for socket open and connect

- When calling socket APIs when socket is not open, NSAPI_ERROR_NO_SOCKET will be
  returned instead of generic NSAPI_ERROR_DEVICE_ERROR

- If socket_send() is called when connection is not open, NSAPI_ERROR_NO_CONNECTION
  will be returned instead of generic NSAPI_ERROR_DEVICE_ERROR

Author: Kimmo Vaisanen

UNITTESTS/features/cellular/framework/AT/at_cellularstack/at_cellularstacktest.cpp

@@ -244,7 +244,7 @@ TEST_F(TestAT_CellularStack, test_AT_CellularStack_socket_bind)
     MyStack st(at, 0, IPV6_STACK);
     SocketAddress addr;
     ATHandler_stub::nsapi_error_value = NSAPI_ERROR_ALREADY;
-    EXPECT_EQ(st.socket_bind(NULL, addr), NSAPI_ERROR_DEVICE_ERROR);
+    EXPECT_EQ(st.socket_bind(NULL, addr), NSAPI_ERROR_NO_SOCKET);
 
     EXPECT_EQ(st.socket_bind(&st.socket, addr), NSAPI_ERROR_ALREADY);
 }
@@ -267,7 +267,7 @@ TEST_F(TestAT_CellularStack, test_AT_CellularStack_socket_connect)
 
     MyStack st(at, 0, IPV6_STACK);
     SocketAddress addr;
-    EXPECT_EQ(st.socket_connect(NULL, addr), NSAPI_ERROR_DEVICE_ERROR);
+    EXPECT_EQ(st.socket_connect(NULL, addr), NSAPI_ERROR_NO_SOCKET);
 
     EXPECT_EQ(st.socket_connect(&st.socket, addr), NSAPI_ERROR_OK);
 }
@@ -290,9 +290,9 @@ TEST_F(TestAT_CellularStack, test_AT_CellularStack_socket_send)
     ATHandler at(&fh1, que, 0, ",");
 
     MyStack st(at, 0, IPV6_STACK);
-    EXPECT_EQ(st.socket_send(NULL, "addr", 4), NSAPI_ERROR_DEVICE_ERROR);
+    EXPECT_EQ(st.socket_send(NULL, "addr", 4), NSAPI_ERROR_NO_SOCKET);
 
-    EXPECT_EQ(st.socket_send(&st.socket, "addr", 4), NSAPI_ERROR_DEVICE_ERROR);
+    EXPECT_EQ(st.socket_send(&st.socket, "addr", 4), NSAPI_ERROR_NO_CONNECTION);
 
     SocketAddress addr;
     st.max_sock_value = 1;
@@ -312,7 +312,7 @@ TEST_F(TestAT_CellularStack, test_AT_CellularStack_socket_sendto)
     MyStack st(at, 0, IPV6_STACK);
 
     SocketAddress addr;
-    EXPECT_EQ(st.socket_sendto(NULL, addr, "addr", 4), NSAPI_ERROR_DEVICE_ERROR);
+    EXPECT_EQ(st.socket_sendto(NULL, addr, "addr", 4), NSAPI_ERROR_NO_SOCKET);
 
     st.max_sock_value = 1;
     st.bool_value = true;
@@ -334,7 +334,7 @@ TEST_F(TestAT_CellularStack, test_AT_CellularStack_socket_recv)
 
     MyStack st(at, 0, IPV6_STACK);
     char table[4];
-    EXPECT_EQ(st.socket_recv(NULL, table, 4), NSAPI_ERROR_DEVICE_ERROR);
+    EXPECT_EQ(st.socket_recv(NULL, table, 4), NSAPI_ERROR_NO_SOCKET);
 }
 
 TEST_F(TestAT_CellularStack, test_AT_CellularStack_socket_recvfrom)
@@ -345,7 +345,7 @@ TEST_F(TestAT_CellularStack, test_AT_CellularStack_socket_recvfrom)
 
     MyStack st(at, 0, IPV6_STACK);
     char table[4];
-    EXPECT_EQ(st.socket_recvfrom(NULL, NULL, table, 4), NSAPI_ERROR_DEVICE_ERROR);
+    EXPECT_EQ(st.socket_recvfrom(NULL, NULL, table, 4), NSAPI_ERROR_NO_SOCKET);
 
     SocketAddress addr;
     st.max_sock_value = 1;

features/cellular/framework/AT/AT_CellularStack.cpp

@@ -156,7 +156,7 @@ nsapi_error_t AT_CellularStack::socket_close(nsapi_socket_t handle)
 
     struct CellularSocket *socket = (struct CellularSocket *)handle;
     if (!socket) {
-        return err;
+        return NSAPI_ERROR_NO_SOCKET;
     }
     int sock_id = socket->id;
 
@@ -192,7 +192,7 @@ nsapi_error_t AT_CellularStack::socket_bind(nsapi_socket_t handle, const SocketA
 {
     struct CellularSocket *socket = (CellularSocket *)handle;
     if (!socket) {
-        return NSAPI_ERROR_DEVICE_ERROR;
+        return NSAPI_ERROR_NO_SOCKET;
     }
 
     if (addr) {
@@ -220,14 +220,14 @@ nsapi_error_t AT_CellularStack::socket_bind(nsapi_socket_t handle, const SocketA
 
 nsapi_error_t AT_CellularStack::socket_listen(nsapi_socket_t handle, int backlog)
 {
-    return NSAPI_ERROR_UNSUPPORTED;;
+    return NSAPI_ERROR_UNSUPPORTED;
 }
 
 nsapi_error_t AT_CellularStack::socket_connect(nsapi_socket_t handle, const SocketAddress &addr)
 {
     CellularSocket *socket = (CellularSocket *)handle;
     if (!socket) {
-        return NSAPI_ERROR_DEVICE_ERROR;
+        return NSAPI_ERROR_NO_SOCKET;
     }
     socket->remoteAddress = addr;
     socket->connected = true;
@@ -237,14 +237,17 @@ nsapi_error_t AT_CellularStack::socket_connect(nsapi_socket_t handle, const Sock
 
 nsapi_error_t AT_CellularStack::socket_accept(void *server, void **socket, SocketAddress *addr)
 {
-    return NSAPI_ERROR_UNSUPPORTED;;
+    return NSAPI_ERROR_UNSUPPORTED;
 }
 
 nsapi_size_or_error_t AT_CellularStack::socket_send(nsapi_socket_t handle, const void *data, unsigned size)
 {
     CellularSocket *socket = (CellularSocket *)handle;
-    if (!socket || !socket->connected) {
-        return NSAPI_ERROR_DEVICE_ERROR;
+    if (!socket) {
+        return NSAPI_ERROR_NO_SOCKET;
+    }
+    if (!socket->connected) {
+        return NSAPI_ERROR_NO_CONNECTION;
     }
     return socket_sendto(handle, socket->remoteAddress, data, size);
 }
@@ -253,7 +256,7 @@ nsapi_size_or_error_t AT_CellularStack::socket_sendto(nsapi_socket_t handle, con
 {
     CellularSocket *socket = (CellularSocket *)handle;
     if (!socket) {
-        return NSAPI_ERROR_DEVICE_ERROR;
+        return NSAPI_ERROR_NO_SOCKET;
     }
 
     if (socket->closed && !socket->rx_avail) {
@@ -319,7 +322,7 @@ nsapi_size_or_error_t AT_CellularStack::socket_recvfrom(nsapi_socket_t handle, S
 {
     CellularSocket *socket = (CellularSocket *)handle;
     if (!socket) {
-        return NSAPI_ERROR_DEVICE_ERROR;
+        return NSAPI_ERROR_NO_SOCKET;
     }
 
     if (socket->closed) {