Add API to constrain the use of the Router/Leader role. (#285)

include/openthread.h

@@ -478,6 +478,23 @@ otPanId otGetPanId(void);
  */
 ThreadError otSetPanId(otPanId aPanId);
 
+/**
+ * This function indicates whether or not the Router Role is enabled.
+ *
+ * @retval TRUE   If the Router Role is enabled.
+ * @retval FALSE  If the Router Role is not enabled.
+ *
+ */
+bool otIsRouterRoleEnabled(void);
+
+/**
+ * This function sets whether or not the Router Role is enabled.
+ *
+ * @param[in]  aEnabled  TRUE if the Router Role is enabled, FALSE otherwise.
+ *
+ */
+void otSetRouterRoleEnabled(bool aEnabled);
+
 /**
  * Get the IEEE 802.15.4 Short Address.
  *

src/core/openthread.cpp

@@ -250,6 +250,16 @@ ThreadError otSetPanId(otPanId aPanId)
     return sThreadNetif->GetMac().SetPanId(aPanId);
 }
 
+bool otIsRouterRoleEnabled(void)
+{
+    return sThreadNetif->GetMle().IsRouterRoleEnabled();
+}
+
+void otSetRouterRoleEnabled(bool aEnabled)
+{
+    sThreadNetif->GetMle().SetRouterRoleEnabled(aEnabled);
+}
+
 otShortAddress otGetShortAddress(void)
 {
     return sThreadNetif->GetMac().GetShortAddress();

src/core/thread/mle_router.cpp

@@ -68,10 +68,26 @@ MleRouter::MleRouter(ThreadNetif &aThreadNetif):
     mPreviousRouterId = kMaxRouterId;
     mAdvertiseInterval = kAdvertiseIntervalMin;
     mRouterIdSequenceLastUpdated = 0;
+    mRouterRoleEnabled = true;
 
     mCoapMessageId = otPlatRandomGet();
 }
 
+bool MleRouter::IsRouterRoleEnabled(void) const
+{
+    return mRouterRoleEnabled && (mDeviceMode & ModeTlv::kModeFFD);
+}
+
+void MleRouter::SetRouterRoleEnabled(bool aEnabled)
+{
+    mRouterRoleEnabled = aEnabled;
+
+    if (!mRouterRoleEnabled && (mDeviceState == kDeviceStateRouter || mDeviceState == kDeviceStateLeader))
+    {
+        BecomeDetached();
+    }
+}
+
 int MleRouter::AllocateRouterId(void)
 {
     int rval = -1;
@@ -167,7 +183,7 @@ ThreadError MleRouter::BecomeRouter(void)
 
     VerifyOrExit(mDeviceState == kDeviceStateDetached || mDeviceState == kDeviceStateChild,
                  error = kThreadError_Busy);
-    VerifyOrExit(mDeviceMode & ModeTlv::kModeFFD, ;);
+    VerifyOrExit(mRouterRoleEnabled && (mDeviceMode & ModeTlv::kModeFFD), ;);
 
     for (int i = 0; i < kMaxRouterId; i++)
     {

src/core/thread/mle_router.hpp

@@ -76,6 +76,26 @@ public:
      */
     explicit MleRouter(ThreadNetif &aThreadNetif);
 
+    /**
+     * This method indicates whether or not the Router Role is enabled.
+     *
+     * @retval true   If the Router Role is enabled.
+     * @retval false  If the Router Role is not enabled.
+     *
+     */
+    bool IsRouterRoleEnabled(void) const;
+
+    /**
+     * This method sets whether or not the Router Role is enabled.
+     *
+     * If @p aEnable is false and the device is currently operating as a router, this call will cause the device to
+     * detach and attempt to reattach as a child.
+     *
+     * @param[in]  aEnabled  TRUE to enable the Router Role, FALSE otherwise.
+     *
+     */
+    void SetRouterRoleEnabled(bool aEnabled);
+
     /**
      * This method generates an Address Solicit request for a Router ID.
      *
@@ -436,6 +456,7 @@ private:
     uint8_t mNetworkIdTimeout;
     uint8_t mRouterUpgradeThreshold;
     uint8_t mLeaderWeight;
+    bool mRouterRoleEnabled;
 
     int8_t mRouterId;
     int8_t mPreviousRouterId;