Line data    Source code

       1             : // SPDX-License-Identifier: Apache-2.0
       2             : // Copyright(c) 2023 Cisco Systems, Inc.
       3             : 
       4             : /*
       5             :  * npt66.c: NPT66 plugin
       6             :  * An implementation of Network Prefix Translation for IPv6-to-IPv6 (NPTv6) as
       7             :  * specified in RFC6296.
       8             :  */
       9             : 
      10             : #include <stdio.h>
      11             : #include <stdint.h>
      12             : #include <inttypes.h>
      13             : #include <vlib/vlib.h>
      14             : #include <vnet/feature/feature.h>
      15             : #include <vppinfra/pool.h>
      16             : #include "npt66.h"
      17             : 
      18             : static int
      19          16 : npt66_feature_enable_disable (u32 sw_if_index, bool is_add)
      20             : {
      21          16 :   if (vnet_feature_enable_disable ("ip6-unicast", "npt66-input", sw_if_index,
      22             :                                    is_add, 0, 0) != 0)
      23           0 :     return -1;
      24          16 :   if (vnet_feature_enable_disable ("ip6-output", "npt66-output", sw_if_index,
      25             :                                    is_add, 0, 0) != 0)
      26           0 :     return -1;
      27          16 :   return 0;
      28             : }
      29             : 
      30             : static void
      31          16 : ipv6_prefix_zero (ip6_address_t *address, int prefix_len)
      32             : {
      33          16 :   int byte_index = prefix_len / 8;
      34          16 :   int bit_offset = prefix_len % 8;
      35          16 :   uint8_t mask = (1 << (8 - bit_offset)) - 1;
      36          16 :   if (byte_index < 16)
      37             :     {
      38          16 :       address->as_u8[byte_index] &= mask;
      39         164 :       for (int i = byte_index + 1; i < 16; i++)
      40             :         {
      41         148 :           address->as_u8[i] = 0;
      42             :         }
      43             :     }
      44          16 : }
      45             : 
      46             : int
      47          16 : npt66_binding_add_del (u32 sw_if_index, ip6_address_t *internal,
      48             :                        int internal_plen, ip6_address_t *external,
      49             :                        int external_plen, bool is_add)
      50             : {
      51          16 :   npt66_main_t *nm = &npt66_main;
      52          16 :   int rv = 0;
      53             : 
      54             :   /* Currently limited to a single binding per interface */
      55          16 :   npt66_binding_t *b = npt66_interface_by_sw_if_index (sw_if_index);
      56             : 
      57          16 :   if (is_add)
      58             :     {
      59           8 :       bool configure_feature = false;
      60             :       /* Ensure prefix lengths are less than or equal to a /64 */
      61           8 :       if (internal_plen > 64 || external_plen > 64)
      62           0 :         return VNET_API_ERROR_INVALID_VALUE;
      63             : 
      64             :       /* Create a binding entry (or update existing) */
      65           8 :       if (!b)
      66             :         {
      67           8 :           pool_get_zero (nm->bindings, b);
      68           8 :           configure_feature = true;
      69             :         }
      70           8 :       b->internal = *internal;
      71           8 :       b->internal_plen = internal_plen;
      72           8 :       b->external = *external;
      73           8 :       b->external_plen = external_plen;
      74           8 :       b->sw_if_index = sw_if_index;
      75             : 
      76           8 :       ipv6_prefix_zero (&b->internal, internal_plen);
      77           8 :       ipv6_prefix_zero (&b->external, external_plen);
      78          11 :       vec_validate_init_empty (nm->interface_by_sw_if_index, sw_if_index, ~0);
      79           8 :       nm->interface_by_sw_if_index[sw_if_index] = b - nm->bindings;
      80             : 
      81           8 :       uword delta = 0;
      82           8 :       delta = ip_csum_add_even (delta, b->external.as_u64[0]);
      83           8 :       delta = ip_csum_add_even (delta, b->external.as_u64[1]);
      84           8 :       delta = ip_csum_sub_even (delta, b->internal.as_u64[0]);
      85           8 :       delta = ip_csum_sub_even (delta, b->internal.as_u64[1]);
      86           8 :       delta = ip_csum_fold (delta);
      87           8 :       b->delta = delta;
      88             : 
      89           8 :       if (configure_feature)
      90           8 :         rv = npt66_feature_enable_disable (sw_if_index, is_add);
      91             :     }
      92             :   else
      93             :     {
      94             :       /* Delete a binding entry */
      95           8 :       npt66_binding_t *b = npt66_interface_by_sw_if_index (sw_if_index);
      96           8 :       if (!b)
      97           0 :         return VNET_API_ERROR_NO_SUCH_ENTRY;
      98           8 :       nm->interface_by_sw_if_index[sw_if_index] = ~0;
      99           8 :       pool_put (nm->bindings, b);
     100           8 :       rv = npt66_feature_enable_disable (sw_if_index, is_add);
     101             :     }
     102             : 
     103          16 :   return rv;
     104             : }
     105             : 
     106             : /*
     107             :  * Do a lookup in the interface vector (interface_by_sw_if_index)
     108             :  * and return pool entry.
     109             :  */
     110             : npt66_binding_t *
     111          41 : npt66_interface_by_sw_if_index (u32 sw_if_index)
     112             : {
     113          41 :   npt66_main_t *nm = &npt66_main;
     114             : 
     115          81 :   if (!nm->interface_by_sw_if_index ||
     116          40 :       sw_if_index > (vec_len (nm->interface_by_sw_if_index) - 1))
     117           1 :     return 0;
     118          40 :   u32 index = nm->interface_by_sw_if_index[sw_if_index];
     119          40 :   if (index == ~0)
     120           7 :     return 0;
     121          33 :   if (pool_is_free_index (nm->bindings, index))
     122           0 :     return 0;
     123          33 :   return pool_elt_at_index (nm->bindings, index);
     124             : }