encap.c

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/*
 * encap.c : L2TPv3 tunnel encapsulation
 *
 * Copyright (c) 2013 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <vppinfra/error.h>
#include <vppinfra/hash.h>
#include <vnet/vnet.h>
#include <vnet/ip/ip.h>
#include <vnet/ethernet/ethernet.h>
#include <vnet/l2tp/l2tp.h>

/* Statistics (not really errors) */
#define foreach_l2t_encap_error                                 \
_(NETWORK_TO_USER, "L2TP L2 network to user (ip6) pkts")        \
_(LOOKUP_FAIL_TO_L3, "L2TP L2 session lookup failed pkts")

static char * l2t_encap_error_strings[] = {
#define _(sym,string) string,
  foreach_l2t_encap_error
#undef _
};

typedef enum {
#define _(sym,str) L2T_ENCAP_ERROR_##sym,
    foreach_l2t_encap_error
#undef _
    L2T_ENCAP_N_ERROR,
} l2t_encap_error_t;


typedef enum {
    L2T_ENCAP_NEXT_DROP,
    L2T_ENCAP_NEXT_IP6_LOOKUP,
    L2T_ENCAP_N_NEXT,
} l2t_encap_next_t;

typedef struct {
  u32 cached_session_index;
  u32 cached_sw_if_index;
  vnet_main_t * vnet_main;
} l2tp_encap_runtime_t;

vlib_node_registration_t l2t_encap_node;

#define NSTAGES 3

static inline void stage0 (vlib_main_t * vm,
                           vlib_node_runtime_t * node,
                           u32 buffer_index)
{
    vlib_buffer_t *b = vlib_get_buffer (vm, buffer_index);
    vlib_prefetch_buffer_header (b, STORE);
    CLIB_PREFETCH (b->data, 2*CLIB_CACHE_LINE_BYTES, STORE);
}

static inline void stage1 (vlib_main_t * vm,
                           vlib_node_runtime_t * node,
                           u32 bi)
{
    l2tp_encap_runtime_t * rt = (void *) node->runtime_data;
    vlib_buffer_t *b = vlib_get_buffer (vm, bi);
    vnet_hw_interface_t * hi;

    u32 sw_if_index = vnet_buffer(b)->sw_if_index[VLIB_TX];
    u32 session_index = rt->cached_session_index;

    if (PREDICT_FALSE(rt->cached_sw_if_index != sw_if_index))
    {
        hi = vnet_get_sup_hw_interface (rt->vnet_main, sw_if_index);
        session_index = rt->cached_session_index = hi->dev_instance;
        rt->cached_sw_if_index = sw_if_index;        
    }

    /* Remember mapping index, prefetch the mini counter */
    vnet_buffer(b)->l2t.next_index = L2T_ENCAP_NEXT_IP6_LOOKUP;
    vnet_buffer(b)->l2t.session_index = session_index;

    /* $$$$ prefetch counter... */
}

static inline u32 last_stage (vlib_main_t *vm, vlib_node_runtime_t *node,
                              u32 bi)
{
    vlib_buffer_t *b = vlib_get_buffer (vm, bi);
    l2t_main_t *lm = &l2t_main;
    vlib_node_t *n = vlib_get_node (vm, l2t_encap_node.index);
    u32 node_counter_base_index = n->error_heap_index;
    vlib_error_main_t * em = &vm->error_main;
    l2tpv3_header_t * l2tp;
    u32 session_index;
    u32 counter_index;
    l2t_session_t *s;
    ip6_header_t *ip6;
    u16 payload_length;

    /* Other-than-output pkt? We're done... */
    if (vnet_buffer(b)->l2t.next_index != L2T_ENCAP_NEXT_IP6_LOOKUP)
        return vnet_buffer(b)->l2t.next_index;

    /* clear so it is not interpreted as fib_index */
    vnet_buffer(b)->sw_if_index[VLIB_TX] = (u32)~0;

    em->counters[node_counter_base_index + L2T_ENCAP_ERROR_NETWORK_TO_USER] += 1;
    
    session_index = vnet_buffer(b)->l2t.session_index;

    counter_index = 
        session_index_to_counter_index (session_index,
                                        SESSION_COUNTER_NETWORK_TO_USER);
    
    /* per-mapping byte stats include the ethernet header */
    vlib_increment_combined_counter (&lm->counter_main,
                                     os_get_cpu_number(),
                                     counter_index, 
                                     1 /* packet_increment */,
                                     vlib_buffer_length_in_chain (vm, b));
    
    s = pool_elt_at_index (lm->sessions, session_index);

    /* Paint on an l2tpv3 hdr */
    vlib_buffer_advance (b, -(s->l2tp_hdr_size));
    l2tp = vlib_buffer_get_current (b);

    l2tp->session_id = s->remote_session_id;
    l2tp->cookie = s->remote_cookie;
    if (PREDICT_FALSE (s->l2_sublayer_present)) {
        l2tp->l2_specific_sublayer = 0;
    }

    /* Paint on an ip6 header */
    vlib_buffer_advance (b, -(sizeof (*ip6)));
    ip6 = vlib_buffer_get_current (b);

    ip6->ip_version_traffic_class_and_flow_label = 
        clib_host_to_net_u32 (0x6<<28);

    /* calculate ip6 payload length */
    payload_length = vlib_buffer_length_in_chain (vm, b);
    payload_length -= sizeof (*ip6);

    ip6->payload_length = clib_host_to_net_u16 (payload_length);
    ip6->protocol = IP_PROTOCOL_L2TP;
    ip6->hop_limit = 0xff;
    ip6->src_address.as_u64[0] = s->our_address.as_u64[0];
    ip6->src_address.as_u64[1] = s->our_address.as_u64[1];
    ip6->dst_address.as_u64[0] = s->client_address.as_u64[0];
    ip6->dst_address.as_u64[1] = s->client_address.as_u64[1];

    if (PREDICT_FALSE(b->flags & VLIB_BUFFER_IS_TRACED)) {
        l2t_trace_t *t = vlib_add_trace (vm, node, b, sizeof (*t));
        t->is_user_to_network = 0;
        t->our_address.as_u64[0] =
            ip6->src_address.as_u64[0];
        t->our_address.as_u64[1] =
            ip6->src_address.as_u64[1];
        t->client_address.as_u64[0] =
            ip6->dst_address.as_u64[0];
        t->client_address.as_u64[1] =
            ip6->dst_address.as_u64[1];
        t->session_index = session_index;
    }

    return L2T_ENCAP_NEXT_IP6_LOOKUP;
}

#include <vnet/pipeline.h>

uword l2t_encap_node_fn (vlib_main_t * vm,
                      vlib_node_runtime_t * node,
                      vlib_frame_t * frame)
{
    return dispatch_pipeline (vm, node, frame);
}


VLIB_REGISTER_NODE (l2t_encap_node) = {
  .function = l2t_encap_node_fn,
  .name = "l2tp-encap",
  .vector_size = sizeof (u32),
  .format_trace = format_l2t_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .runtime_data_bytes = sizeof (l2tp_encap_runtime_t),
  
  .n_errors = ARRAY_LEN(l2t_encap_error_strings),
  .error_strings = l2t_encap_error_strings,

  .n_next_nodes = L2T_ENCAP_N_NEXT,

  //  add dispositions here
  .next_nodes = {
        [L2T_ENCAP_NEXT_IP6_LOOKUP] = "ip6-lookup",
        [L2T_ENCAP_NEXT_DROP] = "error-drop",
  },
};

void l2tp_encap_init (vlib_main_t * vm)
{
  l2tp_encap_runtime_t * rt;

  rt = vlib_node_get_runtime_data (vm, l2t_encap_node.index);
  rt->vnet_main = vnet_get_main();
  rt->cached_sw_if_index = (u32) ~0;
  rt->cached_session_index = (u32) ~0;
}