Basics of NSM logic and internals

eRINA_STM32F7/src/rina/namespace_manager.adb

@@ -0,0 +1,82 @@
+with Ada.Numerics.Discrete_Random;
+
+package body Namespace_Manager is
+    -- instantiate IPCP to App Names map when NSM created inside a DIF
+    IPCP_To_App_Names : IPCP_Map;
+
+    -- Get IPCP address from app name
+    function Get_IPCP_Address
+       (Self : Namespace_Manager; App_Name : Application_Name)
+        return IPCP_Address
+    is
+        Curr_Name : Application_Name;
+    begin
+        -- for now, linear O(n)
+        for IPCP in IPCP_To_App_Names.Iterate loop
+            Curr_Name := IPCP_To_App_Names (IPCP);
+            if Curr_Name = App_Name then
+                return IPCP;
+            end if;
+        end loop;
+        -- Make user handle error
+        raise Application_Name_Non_Existent;
+    end Get_IPCP_Address;
+
+    -- Get the app name from IPCP Address
+    function Get_Application_Name
+       (IPCP_Addr : IPCP_Address) return Application_Name
+    is
+    begin
+        -- desired route
+        if IPCP_To_App_Names.Contains (IPCP_Addr) then
+            return IPCP_To_App_Names (IPCP_Addr);
+        end if;
+        -- Make user handle error
+        raise Application_Name_Non_Existent;
+    end Get_Application_Name;
+
+    -- store application name with corresponding ipcp address
+    procedure Assign_Application_Name (App_Name : Application_Name) is
+        IPCP_Addr              : IPCP_Address;
+        IPCP_Assigned          : Boolean;
+        Pos                    : Cursor;
+        IPCP_Alloc_Retry_Count : Integer := IPCP_Address'Last + 1;
+    begin
+        -- allocate an unassigned IPCP Address
+        IPCP_Addr := Allocate_IPCP_Address;
+        -- Insert IPCP address into map
+        IPCP_To_App_Names.Insert (IPCP_Addr, App_Name, Pos, IPCP_Assigned);
+
+        -- double check that app name was actually inserted
+        while IPCP_Assigned /= True and IPCP_Alloc_Retry_Count > 0 loop
+            -- retry only as many times as there are addresses
+            IPCP_Addr := Allocate_IPCP_Address;
+            IPCP_To_App_Names.Insert (IPCP_Addr, App_Name, Pos, IPCP_Assigned);
+            -- decrement counter
+            IPCP_Alloc_Retry_Count := IPCP_Alloc_Retry_Count - 1;
+        end loop;
+    end Assign_Application_Name;
+
+    -- helper to allocate new IPCP address
+    function Allocate_IPCP_Address return IPCP_Address is
+        -- Instantiate Random number with range of IPCP Addrs
+        package Random_Addr is new Ada.Numerics.Discrete_Random (IPCP_Address);
+        use Random_Addr;
+        Gen                   : Generator;
+        Addr                  : IPCP_Address;
+        Addr_Already_Assigned : Boolean;
+    begin
+        Reset
+           (Gen); -- seed random number generator with new seed every invocation
+        Addr := Random (Gen); -- choose pseudo random IPCP addr number
+        -- check if IPCP Addr already allocated
+        Addr_Already_Assigned := IPCP_To_App_Names.Contains (Addr);
+        while Addr_Already_Assigned loop
+            Addr := Random (Gen); -- choose pseudo random IPCP addr number
+            Addr_Already_Assigned :=
+               IPCP_To_App_Names.Contains (Addr); -- check again
+        end loop;
+        return Addr;
+    end Allocate_IPCP_Address;
+
+end Namespace_Manager;

eRINA_STM32F7/src/rina/namespace_manager.ads

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+with Names;                      use Names;
+with Ada.Strings.Hash;
+with Ada.Containers.Hashed_Maps; use Ada.Containers;
+
+package Namespace_Manager is
+    -- Possible errors
+    Application_Name_Non_Existent     : exception;
+    Application_Name_Already_Assigned : exception;
+
+    -- IPCP address maps to Application name
+    type Application_Name is
+       new Names_String; -- The endpoint to send and be sent from
+
+    type IPCP_Address is
+       new Integer range 0 .. 255; -- IPCP address range is 1 byte
+
+    -- Map of app names to IPCP addrs
+    package IPCP_To_App is new Ada.Containers.Hashed_Maps
+       (Key_Type => IPCP_Address, Element_Type => Application_Name,
+        Hash     => Integer.Hash, Equivalent_Keys => "=");
+
+    subtype IPCP_Map is
+       IPCP_To_App.Map; -- so we don't have to .Map everytime created
+
+    -- Allow getting assigned names
+    -- and addresses given one or the other
+    function Get_IPCP_Address
+       (Self : Namespace_Manager; App_Name : Application_Name)
+        return IPCP_Address;
+
+    function Get_Application_Name
+       (Self : Namespace_Manager; IPCP_Add : IPCP_Address)
+        return Application_Name;
+
+    -- Allow assigning names to IPCP's
+    procedure Assign_Application_Name (App_Name : Application_Name);
+
+private
+    -- Pseudo-randomly choose IPCP address
+    function Allocate_IPCP_Address return IPCP_Address;
+
+end Namespace_Manager;