[ncp] adding new spinel property to get EID address cache table (#2788)

This commit adds a new spinel property `THREAD_ADDRESS_CACHE_TABLE`
to get the Thread EID IPv6 Address cache table.

doc/spinel-protocol-src/spinel-tech-thread.md

@@ -562,3 +562,17 @@ Data per item is:
 * `S`: Message error rate (0 -> 0%, 0xffff -> 100%)
 * `c`: Average RSSI (in dBm)
 * `c`: Last RSSI (in dBm)
+
+
+### PROP 5411: SPINEL_PROP_THREAD_ADDRESS_CACHE_TABLE (#prop-thread-address-cache-table)
+
+* Type: Read-Only
+* Packing-Encoding: `A(t(6SC))`
+
+This property provides Thread EID IPv6 address cache table.
+
+Data per item is:
+
+* `6` : Target IPv6 address
+* `S` : RLOC16 of target
+* `C` : Age (order of use, 0 indicates most recently used entry)

src/ncp/ncp_base.cpp

@@ -232,6 +232,7 @@ const NcpBase::PropertyHandlerEntry NcpBase::mGetPropertyHandlerTable[] =
     NCP_GET_PROP_HANDLER_ENTRY(THREAD_NETWORK_ID_TIMEOUT),
     NCP_GET_PROP_HANDLER_ENTRY(THREAD_ROUTER_SELECTION_JITTER),
     NCP_GET_PROP_HANDLER_ENTRY(THREAD_PREFERRED_ROUTER_ID),
+    NCP_GET_PROP_HANDLER_ENTRY(THREAD_ADDRESS_CACHE_TABLE),
 #if OPENTHREAD_ENABLE_COMMISSIONER
     NCP_GET_PROP_HANDLER_ENTRY(THREAD_COMMISSIONER_ENABLED),
 #endif

src/ncp/ncp_base.hpp

@@ -670,6 +670,7 @@ protected:
     NCP_SET_PROP_HANDLER(THREAD_PENDING_DATASET);
     NCP_SET_PROP_HANDLER(THREAD_MGMT_ACTIVE_DATASET);
     NCP_SET_PROP_HANDLER(THREAD_MGMT_PENDING_DATASET);
+    NCP_GET_PROP_HANDLER(THREAD_ADDRESS_CACHE_TABLE);
 #if OPENTHREAD_ENABLE_CHANNEL_MANAGER
     NCP_GET_PROP_HANDLER(CHANNEL_MANAGER_NEW_CHANNEL);
     NCP_SET_PROP_HANDLER(CHANNEL_MANAGER_NEW_CHANNEL);

src/ncp/ncp_base_ftd.cpp

@@ -528,6 +528,31 @@ exit:
     return error;
 }
 
+otError NcpBase::GetPropertyHandler_THREAD_ADDRESS_CACHE_TABLE(void)
+{
+    otError         error = OT_ERROR_NONE;
+    otEidCacheEntry entry;
+
+    for (uint8_t index = 0; ; index++)
+    {
+        SuccessOrExit(otThreadGetEidCacheEntry(mInstance, index, &entry));
+
+        if (!entry.mValid)
+        {
+            continue;
+        }
+
+        SuccessOrExit(error = mEncoder.OpenStruct());
+        SuccessOrExit(error = mEncoder.WriteIp6Address(entry.mTarget));
+        SuccessOrExit(error = mEncoder.WriteUint16(entry.mRloc16));
+        SuccessOrExit(error = mEncoder.WriteUint8(entry.mAge));
+        SuccessOrExit(error = mEncoder.CloseStruct());
+    }
+
+exit:
+    return error;
+}
+
 #if OPENTHREAD_ENABLE_TMF_PROXY
 otError NcpBase::GetPropertyHandler_THREAD_TMF_PROXY_ENABLED(void)
 {

src/ncp/spinel.c

@@ -1545,6 +1545,10 @@ spinel_prop_key_to_cstr(spinel_prop_key_t prop_key)
         ret = "PROP_THREAD_NEIGHBOR_TABLE_ERROR_RATES";
         break;
 
+    case SPINEL_PROP_THREAD_ADDRESS_CACHE_TABLE:
+        ret = "PROP_THREAD_ADDRESS_CACHE_TABLE";
+        break;
+
     case SPINEL_PROP_IPV6_LL_ADDR:
         ret = "PROP_IPV6_LL_ADDR";
         break;

src/ncp/spinel.h

@@ -1416,6 +1416,21 @@ typedef enum
     SPINEL_PROP_THREAD_NEIGHBOR_TABLE_ERROR_RATES
                                         = SPINEL_PROP_THREAD_EXT__BEGIN + 34,
 
+    /// EID (Endpoint Identifier) IPv6 Address Cache Table
+    /** Format `A(t(6SC))`
+     *
+     * This property provides Thread EID address cache table.
+     *
+     * Data per item is:
+     *
+     *  `6` : Target IPv6 address
+     *  `S` : RLOC16 of target
+     *  `C` : Age (order of use, 0 indicates most recently used entry)
+     *
+     */
+    SPINEL_PROP_THREAD_ADDRESS_CACHE_TABLE
+                                        = SPINEL_PROP_THREAD_EXT__BEGIN + 35,
+
     SPINEL_PROP_THREAD_EXT__END         = 0x1600,
 
     SPINEL_PROP_IPV6__BEGIN             = 0x60,