[udp] expose UDP receiver API (#3477)

include/openthread/udp.h

@@ -73,6 +73,30 @@ typedef struct otUdpReceiver
     void *                mContext; ///< A pointer to application-specific context.
 } otUdpReceiver;
 
+/**
+ * This function adds a UDP receiver.
+ *
+ * @param[in]   aInstance       A pointer to an OpenThread instance.
+ * @param[in]   aUdpReceiver    A pointer to the UDP receiver.
+ *
+ * @retval  OT_ERROR_NONE       The receiver is successfully added.
+ * @retval  OT_ERROR_ALREADY    The UDP receiver was already added.
+ *
+ */
+otError otUdpAddReceiver(otInstance *aInstance, otUdpReceiver *aUdpReceiver);
+
+/**
+ * This function removes a UDP receiver.
+ *
+ * @param[in]   aInstance       A pointer to an OpenThread instance.
+ * @param[in]   aUdpReceiver    A pointer to the UDP receiver.
+ *
+ * @retval  OT_ERROR_NONE       The receiver is successfully removed.
+ * @retval  OT_ERROR_NOT_FOUND  The UDP receiver was not added.
+ *
+ */
+otError otUdpRemoveReceiver(otInstance *aInstance, otUdpReceiver *aUdpReceiver);
+
 /**
  * This callback allows OpenThread to inform the application of a received UDP message.
  *

src/core/api/udp_api.cpp

@@ -37,6 +37,7 @@
 
 #include "common/instance.hpp"
 #include "common/new.hpp"
+#include "net/udp6.hpp"
 
 using namespace ot;
 
@@ -136,3 +137,17 @@ otUdpSocket *otUdpGetSockets(otInstance *aInstance)
     return instance.Get<Ip6::Ip6>().GetUdp().GetUdpSockets();
 }
 #endif
+
+otError otUdpAddReceiver(otInstance *aInstance, otUdpReceiver *aUdpReceiver)
+{
+    Instance &instance = *static_cast<Instance *>(aInstance);
+
+    return instance.GetIp6().GetUdp().AddReceiver(*static_cast<Ip6::UdpReceiver *>(aUdpReceiver));
+}
+
+otError otUdpRemoveReceiver(otInstance *aInstance, otUdpReceiver *aUdpReceiver)
+{
+    Instance &instance = *static_cast<Instance *>(aInstance);
+
+    return instance.GetIp6().GetUdp().RemoveReceiver(*static_cast<Ip6::UdpReceiver *>(aUdpReceiver));
+}

src/core/net/udp6.cpp

@@ -209,11 +209,13 @@ Udp::Udp(Instance &aInstance)
 
 otError Udp::AddReceiver(UdpReceiver &aReceiver)
 {
+    otError error = OT_ERROR_NONE;
+
     for (UdpReceiver *cur = mReceivers; cur; cur = cur->GetNext())
     {
         if (cur == &aReceiver)
         {
-            ExitNow();
+            ExitNow(error = OT_ERROR_ALREADY);
         }
     }
 
@@ -221,14 +223,18 @@ otError Udp::AddReceiver(UdpReceiver &aReceiver)
     mReceivers = &aReceiver;
 
 exit:
-    return OT_ERROR_NONE;
+    return error;
 }
 
 otError Udp::RemoveReceiver(UdpReceiver &aReceiver)
 {
+    otError error = OT_ERROR_NOT_FOUND;
+
     if (mReceivers == &aReceiver)
     {
         mReceivers = mReceivers->GetNext();
+        aReceiver.SetNext(NULL);
+        error = OT_ERROR_NONE;
     }
     else
     {
@@ -237,14 +243,14 @@ otError Udp::RemoveReceiver(UdpReceiver &aReceiver)
             if (handler->GetNext() == &aReceiver)
             {
                 handler->SetNext(aReceiver.GetNext());
+                aReceiver.SetNext(NULL);
+                error = OT_ERROR_NONE;
                 break;
             }
         }
     }
 
-    aReceiver.SetNext(NULL);
-
-    return OT_ERROR_NONE;
+    return error;
 }
 
 otError Udp::AddSocket(UdpSocket &aSocket)

src/core/net/udp6.hpp

@@ -226,7 +226,8 @@ public:
      *
      * @param[in]  aReceiver  A reference to the UDP receiver.
      *
-     * @retval OT_ERROR_NONE  Successfully added the UDP receiver.
+     * @retval OT_ERROR_NONE    Successfully added the UDP receiver.
+     * @retval OT_ERROR_ALREADY The UDP receiver was already added.
      *
      */
     otError AddReceiver(UdpReceiver &aReceiver);
@@ -236,7 +237,8 @@ public:
      *
      * @param[in]  aReceiver  A reference to the UDP receiver.
      *
-     * @retval OT_ERROR_NONE  Successfully removed the UDP receiver.
+     * @retval OT_ERROR_NONE        Successfully removed the UDP receiver.
+     * @retval OT_ERROR_NOT_FOUND   The UDP receiver was not added.
      *
      */
     otError RemoveReceiver(UdpReceiver &aReceiver);