Add API to get ipv6 link local address.

Protocols like mdns requires IPv6 link local address to be advertised in its
records (AAAA record). LWIP::Interface::bringup() API is creating IPv6 link
local address;But as of now there is no API exposed by mbed-os to get the
IPv6 link local address.

This new API is required to deliver mDNS library support on mbed-os for Cypress
platforms. Unit tested it by invoking get_ipv6_link_local_address with a simple
application.

Author: Jayasankar Nara

TESTS/network/interface/README.md

@@ -155,10 +155,14 @@ Test `NetworkInterface::get_connection_status()`.
 1.  Check that `get_connection_status()` returns status `NSAPI_STATUS_DISCONNECTED`.
 2.  Connect interface.
 3.  Poll the `get_connection_status()` until it returns status `NSAPI_STATUS_GLOBAL_UP`.
-4.  Disconnect interface.
-5.  Check that `get_connection_status()` returns status `NSAPI_STATUS_DISCONNECTED`.
-6.  Repeat connect and disconnect steps 2 to 5 four times.
+4.  (IPv6 only) Get IPv6 link local address using `get_ipv6_link_local_address` API.
+5.  (IPv6 only) Check that `get_ipv6_link_local_address` returned status `NSAPI_ERROR_OK`.
+6.  (IPv6 only) Check that the IP address associated with the Socket Address is not `NULL`.
+7.  (IPv6 only) Check that the IP version of the IPv6 link local address is `NSAPI_IPv6`.
+8.  Disconnect interface.
+9.  Check that `get_connection_status()` returns status `NSAPI_STATUS_DISCONNECTED`.
+10. Repeat connect and disconnect steps 2 to 5 four times.
 
 **Expected result:**
 
-`Connect()` and `disconnect()` calls return `NSAPI_ERROR_OK`. The right status is returned by `get_connection_status()`.
+`Connect()`, `get_ipv6_link_local_address` and `disconnect()` calls return `NSAPI_ERROR_OK`. The right status is returned by `get_connection_status()`. And the right IPv6 link local address is returned by `get_ipv6_link_local_address`.

TESTS/network/interface/networkinterface_status.cpp

@@ -156,6 +156,15 @@ void NETWORKINTERFACE_STATUS_GET()
             ThisThread::sleep_for(500);
         }
 
+#if MBED_CONF_LWIP_IPV6_ENABLED
+        /* if IPv6 is enabled, validate ipv6_link_local_address API*/
+        SocketAddress ipv6_link_local_address  = NULL;
+        err = net->get_ipv6_link_local_address(&ipv6_link_local_address);
+        TEST_ASSERT_EQUAL(NSAPI_ERROR_OK, err);
+        TEST_ASSERT_NOT_NULL(ipv6_link_local_address.get_ip_address());
+        TEST_ASSERT_EQUAL(NSAPI_IPv6, ipv6_link_local_address.get_ip_version());
+#endif
+
         err = net->disconnect();
         TEST_ASSERT_EQUAL(NSAPI_ERROR_OK, err);
 

UNITTESTS/features/netsocket/EthernetInterface/test_EthernetInterface.cpp

@@ -94,6 +94,7 @@ class EmacNetworkStackMock : public OnboardNetworkStack {
         MOCK_CONST_METHOD0(get_connection_status, nsapi_connection_status_t());
         MOCK_METHOD2(get_mac_address, char *(char *buf, nsapi_size_t buflen));
         MOCK_METHOD2(get_ip_address, char *(char *buf, nsapi_size_t buflen));
+        MOCK_METHOD1(get_ipv6_link_local_address, nsapi_error_t(SocketAddress *address));
         MOCK_METHOD2(get_netmask, char *(char *buf, nsapi_size_t buflen));
         MOCK_METHOD2(get_gateway, char *(char *buf, nsapi_size_t buflen));
     };

UNITTESTS/stubs/NetworkInterface_stub.cpp

@@ -31,6 +31,11 @@ const char *NetworkInterface::get_ip_address()
     return 0;
 }
 
+nsapi_error_t NetworkInterface::get_ipv6_link_local_address(SocketAddress *address)
+{
+    return NSAPI_ERROR_UNSUPPORTED;
+}
+
 const char *NetworkInterface::get_netmask()
 {
     return 0;

UNITTESTS/stubs/NetworkStack_stub.cpp

@@ -93,6 +93,12 @@ const char *NetworkStack::get_ip_address()
 {
     return NULL;
 }
+
+nsapi_error_t NetworkStack::get_ipv6_link_local_address(SocketAddress *address)
+{
+    return NSAPI_ERROR_UNSUPPORTED;
+}
+
 const char *NetworkStack::get_ip_address_if(const char *interface_name)
 {
     return NULL;

features/lwipstack/LWIPInterface.cpp

@@ -37,6 +37,7 @@
 #include "lwip/udp.h"
 
 #include "LWIPStack.h"
+#include "lwip_tools.h"
 
 LWIP::Interface *LWIP::Interface::list;
 
@@ -271,6 +272,30 @@ char *LWIP::Interface::get_interface_name(char *buf)
     return buf;
 }
 
+nsapi_error_t LWIP::Interface::get_ipv6_link_local_address(SocketAddress *address)
+{
+#if LWIP_IPV6
+    const ip_addr_t *addr = LWIP::get_ipv6_link_local_addr(&netif);
+    nsapi_addr_t out;
+    bool ret;
+
+    if (!addr) {
+        return NSAPI_ERROR_PARAMETER;
+    }
+
+    ret = convert_lwip_addr_to_mbed(&out, addr);
+    if (ret != true) {
+        return NSAPI_ERROR_PARAMETER;
+    }
+
+    address->set_addr(out);
+
+    return NSAPI_ERROR_OK;
+#else
+    return NSAPI_ERROR_UNSUPPORTED;
+#endif
+}
+
 char *LWIP::Interface::get_ip_address(char *buf, nsapi_size_t buflen)
 {
     const ip_addr_t *addr = LWIP::get_ip_addr(true, &netif);

features/lwipstack/LWIPStack.h

@@ -101,6 +101,13 @@ class LWIP : public OnboardNetworkStack, private mbed::NonCopyable<LWIP> {
          */
         virtual char *get_ip_address(char *buf, nsapi_size_t buflen);
 
+        /** Get the IPv6 link local address in SocketAddress representation
+         *
+         *  @address        SocketAddress representation of the link local IPv6 address
+         *  @return         NSAPI_ERROR_OK on success, or error code
+         */
+        virtual nsapi_error_t get_ipv6_link_local_address(SocketAddress *address);
+
         /** Copies IP address of the name based network interface to user supplied buffer
          *
          * @param    buf        buffer to which IP address will be copied as "W:X:Y:Z"
@@ -571,6 +578,7 @@ class LWIP : public OnboardNetworkStack, private mbed::NonCopyable<LWIP> {
     static const ip_addr_t *get_ip_addr(bool any_addr, const struct netif *netif);
     static const ip_addr_t *get_ipv4_addr(const struct netif *netif);
     static const ip_addr_t *get_ipv6_addr(const struct netif *netif);
+    static const ip_addr_t *get_ipv6_link_local_addr(const struct netif *netif);
 
     static void add_dns_addr(struct netif *lwip_netif, const char *interface_name);
 

features/lwipstack/lwip_tools.cpp

@@ -79,6 +79,23 @@ const ip_addr_t *LWIP::get_ipv4_addr(const struct netif *netif)
     return NULL;
 }
 
+const ip_addr_t *LWIP::get_ipv6_link_local_addr(const struct netif *netif)
+{
+#if LWIP_IPV6
+    if (!netif_is_up(netif)) {
+        return NULL;
+    }
+
+    for (int i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
+        if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) &&
+                ip6_addr_islinklocal(netif_ip6_addr(netif, i))) {
+            return netif_ip_addr6(netif, i);
+        }
+    }
+#endif
+    return NULL;
+}
+
 const ip_addr_t *LWIP::get_ipv6_addr(const struct netif *netif)
 {
 #if LWIP_IPV6

features/netsocket/EMACInterface.cpp

@@ -95,6 +95,15 @@ const char *EMACInterface::get_ip_address()
     return NULL;
 }
 
+nsapi_error_t EMACInterface::get_ipv6_link_local_address(SocketAddress *address)
+{
+    if (_interface) {
+        return _interface->get_ipv6_link_local_address(address);
+    }
+
+    return NSAPI_ERROR_NO_CONNECTION;
+}
+
 const char *EMACInterface::get_netmask()
 {
     if (_interface && _interface->get_netmask(_netmask, sizeof(_netmask))) {

features/netsocket/EMACInterface.h

@@ -103,6 +103,13 @@ class EMACInterface : public virtual NetworkInterface {
      */
     virtual const char *get_ip_address();
 
+    /** Get the IPv6 link local address
+     *
+     *  @address        SocketAddress representation of the link local IPv6 address
+     *  @return         0 on success, negative error code on failure
+     */
+    virtual nsapi_error_t get_ipv6_link_local_address(SocketAddress *address);
+
     /** Get the local network mask
      *
      *  @return         Null-terminated representation of the local network mask