Added primitive nsapi_stack_t and nsapi_stack_api_t structures

Provides a primitive structure for explicitly instantiating
network stack structures/vtables.

- Avoids reoccuring issue with non-gced vtables
- Provides thick api layer for additional nsapi features
- Provides more explicit seperation between implementation and user api

Now implementors have two options:
1. Extend NetworkStack and implement all of the abstract member functions
2. Fill out a nsapi_stack_api_t and provide a NetworkStack with nsapi_create_stack

option 1 provides an easy route for porting single drivers such as the
esp8266 or the c027 and can easily benefit from other C++ classes.

option 2 provides an easy route for porting full network-stacks such as
lwip or nanostack, which provide their own host of networking utilities
and only need a minimal socket interface.

Author: geky

NetworkStack.cpp

@@ -14,9 +14,14 @@
  * limitations under the License.
  */
 
+#include "NetworkStack.h"
 #include "DnsQuery.h"
 #include "mbed.h"
+#include "stddef.h"
+#include <new>
 
+
+// Default NetworkStack operations
 int NetworkStack::gethostbyname(SocketAddress *address, const char *name)
 {
     char buffer[NSAPI_IP_SIZE];
@@ -48,3 +53,199 @@ int NetworkStack::getsockopt(void *handle, int level, int optname, void *optval,
 {
     return NSAPI_ERROR_UNSUPPORTED;
 }
+
+
+// NetworkStackWrapper class for encapsulating the raw nsapi_stack structure
+class NetworkStackWrapper : public NetworkStack
+{
+private:
+    inline nsapi_stack_t *_stack()
+    {
+        return reinterpret_cast<nsapi_stack_t *>(
+                reinterpret_cast<uint8_t *>(this)
+                - offsetof(nsapi_stack_t, _stack_buffer));
+    }
+
+    inline const nsapi_stack_api_t *_stack_api()
+    {
+        return _stack()->stack_api;
+    }
+
+public:
+    virtual const char *get_ip_address()
+    {
+        if (!_stack_api()->get_ip_address) {
+            return 0;
+        }
+
+        static uint8_t buffer[sizeof(SocketAddress)];
+        SocketAddress *address = new (buffer) SocketAddress(_stack_api()->get_ip_address(_stack()));
+        return address->get_ip_address();
+    }
+
+    virtual int gethostbyname(SocketAddress *address, const char *name)
+    {
+        if (!_stack_api()->gethostbyname) {
+            return NetworkStack::gethostbyname(address, name);
+        }
+
+        nsapi_addr_t addr = {NSAPI_IPv4, 0};
+        int err = _stack_api()->gethostbyname(_stack(), &addr, name);
+        address->set_addr(addr);
+        return err;
+    }
+
+    virtual int setstackopt(int level, int optname, const void *optval, unsigned optlen)
+    {
+        if (!_stack_api()->setstackopt) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->setstackopt(_stack(), level, optname, optval, optlen);
+    }
+
+    virtual int getstackopt(int level, int optname, void *optval, unsigned *optlen)
+    {
+        if (!_stack_api()->getstackopt) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->getstackopt(_stack(), level, optname, optval, optlen);
+    }
+
+protected:
+    virtual int socket_open(nsapi_socket_t *socket, nsapi_protocol_t proto)
+    {
+        if (!_stack_api()->socket_open) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->socket_open(_stack(), socket, proto);
+    }
+
+    virtual int socket_close(nsapi_socket_t socket)
+    {
+        if (!_stack_api()->socket_close) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->socket_close(_stack(), socket);
+    }
+
+    virtual int socket_bind(nsapi_socket_t socket, const SocketAddress &address)
+    {
+        if (!_stack_api()->socket_bind) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->socket_bind(_stack(), socket, address.get_addr(), address.get_port());
+    }
+
+    virtual int socket_listen(nsapi_socket_t socket, int backlog)
+    {
+        if (!_stack_api()->socket_listen) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->socket_listen(_stack(), socket, backlog);
+    }
+
+    virtual int socket_connect(nsapi_socket_t socket, const SocketAddress &address)
+    {
+        if (!_stack_api()->socket_connect) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->socket_connect(_stack(), socket, address.get_addr(), address.get_port());
+    }
+
+    virtual int socket_accept(nsapi_socket_t *socket, nsapi_socket_t server)
+    {
+        if (!_stack_api()->socket_accept) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->socket_accept(_stack(), socket, server);
+    }
+
+    virtual int socket_send(nsapi_socket_t socket, const void *data, unsigned size)
+    {
+        if (!_stack_api()->socket_send) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->socket_send(_stack(), socket, data, size);
+    }
+
+    virtual int socket_recv(nsapi_socket_t socket, void *data, unsigned size)
+    {
+        if (!_stack_api()->socket_recv) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->socket_recv(_stack(), socket, data, size);
+    }
+
+    virtual int socket_sendto(nsapi_socket_t socket, const SocketAddress &address, const void *data, unsigned size)
+    {
+        if (!_stack_api()->socket_sendto) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->socket_sendto(_stack(), socket, address.get_addr(), address.get_port(), data, size);
+    }
+
+    virtual int socket_recvfrom(nsapi_socket_t socket, SocketAddress *address, void *data, unsigned size)
+    {
+        if (!_stack_api()->socket_recvfrom) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        nsapi_addr_t addr = {NSAPI_IPv4, 0};
+        uint16_t port = 0;
+
+        int err = _stack_api()->socket_recvfrom(_stack(), socket, &addr, &port, data, size);
+
+        if (address) {
+            address->set_addr(addr);
+            address->set_port(port);
+        }
+
+        return err;
+    }
+
+    virtual void socket_attach(nsapi_socket_t socket, void (*callback)(void *), void *data)
+    {
+        if (!_stack_api()->socket_attach) {
+            return;
+        }
+
+        return _stack_api()->socket_attach(_stack(), socket, callback, data);
+    }
+
+    virtual int setsockopt(nsapi_socket_t socket, int level, int optname, const void *optval, unsigned optlen)
+    {
+        if (!_stack_api()->setsockopt) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->setsockopt(_stack(), socket, level, optname, optval, optlen);
+    }
+
+    virtual int getsockopt(nsapi_socket_t socket, int level, int optname, void *optval, unsigned *optlen)
+    {
+        if (!_stack_api()->getsockopt) {
+            return NSAPI_ERROR_UNSUPPORTED;
+        }
+
+        return _stack_api()->getsockopt(_stack(), socket, level, optname, optval, optlen);
+    }
+};
+
+
+// Conversion function for network stacks
+NetworkStack *nsapi_create_stack(nsapi_stack_t *stack)
+{
+    MBED_ASSERT(sizeof stack->_stack_buffer >= sizeof(NetworkStackWrapper));
+    return new (stack->_stack_buffer) NetworkStackWrapper;
+}

NetworkStack.h

@@ -278,4 +278,12 @@ class NetworkStack
 };
 
 
+/** Convert a raw nsapi_stack_t object into a C++ NetworkStack object
+ *
+ *  @param stack    Reference to a raw nsapi_stack_t object
+ *  @return         Reference to the underlying network stack
+ */
+NetworkStack *nsapi_create_stack(nsapi_stack_t *stack);
+
+
 #endif