/*
 * Copyright (c) 2016 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 <vnet/adj/adj_nbr.h>
#include <vnet/adj/adj_internal.h>
#include <vnet/adj/adj_l2.h>
#include <vnet/adj/adj_midchain.h>
#include <vnet/ethernet/arp_packet.h>
#include <vnet/dpo/drop_dpo.h>
#include <vnet/fib/fib_walk.h>

/**
 * The two midchain tx feature node indices
 */
static u32 adj_midchain_tx_feature_node[FIB_LINK_NUM];
static u32 adj_midchain_tx_no_count_feature_node[FIB_LINK_NUM];

/**
 * @brief Trace data for packets traversing the midchain tx node
 */
typedef struct adj_midchain_tx_trace_t_
{
    /**
     * @brief the midchain adj we are traversing
     */
    adj_index_t ai;
} adj_midchain_tx_trace_t;

always_inline uword
adj_mdichain_tx_inline (vlib_main_t * vm,
			vlib_node_runtime_t * node,
			vlib_frame_t * frame,
			int interface_count)
{
    u32 * from, * to_next, n_left_from, n_left_to_next;
    u32 next_index;
    vnet_main_t *vnm = vnet_get_main ();
    vnet_interface_main_t *im = &vnm->interface_main;
    u32 cpu_index = vm->cpu_index;

    /* Vector of buffer / pkt indices we're supposed to process */
    from = vlib_frame_vector_args (frame);

    /* Number of buffers / pkts */
    n_left_from = frame->n_vectors;

    /* Speculatively send the first buffer to the last disposition we used */
    next_index = node->cached_next_index;

    while (n_left_from > 0)
    {
	/* set up to enqueue to our disposition with index = next_index */
	vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

	/*
	 * FIXME DUAL LOOP
	 */

	while (n_left_from > 0 && n_left_to_next > 0)
	{
	    u32 bi0, adj_index0, next0;
	    const ip_adjacency_t * adj0;
	    const dpo_id_t *dpo0;
	    vlib_buffer_t * b0;

	    bi0 = from[0];
	    to_next[0] = bi0;
	    from += 1;
	    to_next += 1;
	    n_left_from -= 1;
	    n_left_to_next -= 1;

	    b0 = vlib_get_buffer(vm, bi0);

	    /* Follow the DPO on which the midchain is stacked */
	    adj_index0 = vnet_buffer(b0)->ip.adj_index[VLIB_TX];
	    adj0 = adj_get(adj_index0);
	    dpo0 = &adj0->sub_type.midchain.next_dpo;
	    next0 = dpo0->dpoi_next_node;
	    vnet_buffer(b0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;

	    if (interface_count)
	    {
		vlib_increment_combined_counter (im->combined_sw_if_counters
						 + VNET_INTERFACE_COUNTER_TX,
						 cpu_index,
						 adj0->rewrite_header.sw_if_index,
						 1,
						 vlib_buffer_length_in_chain (vm, b0));
	    }

	    if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
	    {
		adj_midchain_tx_trace_t *tr = vlib_add_trace (vm, node,
							      b0, sizeof (*tr));
		tr->ai = adj_index0;
	    }

	    vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
					     to_next, n_left_to_next,
					     bi0, next0);
	}

	vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

    vlib_node_increment_counter (vm, gre_input_node.index,
				 GRE_ERROR_PKTS_ENCAP, frame->n_vectors);

    return frame->n_vectors;
}

static u8 *
format_adj_midchain_tx_trace (u8 * s, va_list * args)
{
    CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
    CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
    adj_midchain_tx_trace_t *tr = va_arg (*args, adj_midchain_tx_trace_t*);

    s = format(s, "adj-midchain:[%d]:%U", tr->ai,
	       format_ip_adjacency, vnet_get_main(), tr->ai,
	       FORMAT_IP_ADJACENCY_NONE);

    return (s);
}

static uword
adj_midchain_tx (vlib_main_t * vm,
		 vlib_node_runtime_t * node,
		 vlib_frame_t * frame)
{
    return (adj_mdichain_tx_inline(vm, node, frame, 1));
}

VLIB_REGISTER_NODE (adj_midchain_tx_node, static) = {
    .function = adj_midchain_tx,
    .name = "adj-midchain-tx",
    .vector_size = sizeof (u32),

    .format_trace = format_adj_midchain_tx_trace,

    .n_next_nodes = 1,
    .next_nodes = {
	[0] = "error-drop",
    },
};

static uword
adj_midchain_tx_no_count (vlib_main_t * vm,
			  vlib_node_runtime_t * node,
			  vlib_frame_t * frame)
{
    return (adj_mdichain_tx_inline(vm, node, frame, 0));
}

VLIB_REGISTER_NODE (adj_midchain_tx_no_count_node, static) = {
    .function = adj_midchain_tx_no_count,
    .name = "adj-midchain-tx-no-count",
    .vector_size = sizeof (u32),

    .format_trace = format_adj_midchain_tx_trace,

    .n_next_nodes = 1,
    .next_nodes = {
	[0] = "error-drop",
    },
};

VNET_IP4_TX_FEATURE_INIT (adj_midchain_tx_ip4, static) = {
    .node_name = "adj-midchain-tx",
    .runs_before = ORDER_CONSTRAINTS {"interface-output"},
    .feature_index = &adj_midchain_tx_feature_node[FIB_LINK_IP4],
};
VNET_IP4_TX_FEATURE_INIT (adj_midchain_tx_no_count_ip4, static) = {
    .node_name = "adj-midchain-tx-no-count",
    .runs_before = ORDER_CONSTRAINTS {"interface-output"},
    .feature_index = &adj_midchain_tx_no_count_feature_node[FIB_LINK_IP4],
};
VNET_IP6_TX_FEATURE_INIT (adj_midchain_tx_ip6, static) = {
    .node_name = "adj-midchain-tx",
    .runs_before = ORDER_CONSTRAINTS {"interface-output"},
    .feature_index = &adj_midchain_tx_feature_node[FIB_LINK_IP6],
};
VNET_IP6_TX_FEATURE_INIT (adj_midchain_tx_no_count_ip6, static) = {
    .node_name = "adj-midchain-tx-no-count",
    .runs_before = ORDER_CONSTRAINTS {"interface-output"},
    .feature_index = &adj_midchain_tx_no_count_feature_node[FIB_LINK_IP6],
};
VNET_MPLS_TX_FEATURE_INIT (adj_midchain_tx_mpls, static) = {
    .node_name = "adj-midchain-txs",
    .runs_before = ORDER_CONSTRAINTS {"interface-output"},
    .feature_index = &adj_midchain_tx_feature_node[FIB_LINK_MPLS],
};
VNET_MPLS_TX_FEATURE_INIT (adj_midchain_tx_no_count_mpls, static) = {
    .node_name = "adj-midchain-tx-no-count",
    .runs_before = ORDER_CONSTRAINTS {"interface-output"},
    .feature_index = &adj_midchain_tx_no_count_feature_node[FIB_LINK_MPLS],
};
VNET_ETHERNET_TX_FEATURE_INIT (adj_midchain_tx_ethernet, static) = {
    .node_name = "adj-midchain-tx",
    .runs_before = ORDER_CONSTRAINTS {"error-drop"},
    .feature_index = &adj_midchain_tx_feature_node[FIB_LINK_ETHERNET],
};
VNET_ETHERNET_TX_FEATURE_INIT (adj_midchain_tx_no_count_ethernet, static) = {
    .node_name = "adj-midchain-tx-no-count",
    .runs_before = ORDER_CONSTRAINTS {"error-drop"},
    .feature_index = &adj_midchain_tx_no_count_feature_node[FIB_LINK_ETHERNET],
};

static inline u32
adj_get_midchain_node (fib_link_t link)
{
    switch (link) {
    case FIB_LINK_IP4:
	return (ip4_midchain_node.index);
    case FIB_LINK_IP6:
	return (ip6_midchain_node.index);
    case FIB_LINK_MPLS:
	return (mpls_midchain_node.index);
    case FIB_LINK_ETHERNET:
	return (adj_l2_midchain_node.index);
    }
    ASSERT(0);
    return (0);
}

static ip_config_main_t *
adj_midchain_get_cofing_for_link_type (const ip_adjacency_t *adj)
{
    ip_config_main_t *cm = NULL;

    switch (adj->ia_link)
    {
    case FIB_LINK_IP4:
	{
	    ip4_main_t * im = &ip4_main;
	    ip_lookup_main_t * lm = &im->lookup_main;
	    cm = &lm->feature_config_mains[VNET_IP_TX_FEAT];
	    break;
	}
    case FIB_LINK_IP6:
	{
	    ip6_main_t * im = &ip6_main;
	    ip_lookup_main_t * lm = &im->lookup_main;
	    cm = &lm->feature_config_mains[VNET_IP_TX_FEAT];
	    break;
	}
    case FIB_LINK_MPLS:
	{
	    mpls_main_t * mm = &mpls_main;
	    cm = &mm->feature_config_mains[VNET_IP_TX_FEAT];
	    break;
	}
    case FIB_LINK_ETHERNET:
	{
	    cm = &ethernet_main.feature_config_mains[VNET_IP_TX_FEAT];
	    break;
	}
    }

    return (cm);
}

/**
 * adj_nbr_midchain_update_rewrite
 *
 * Update the adjacency's rewrite string. A NULL string implies the
 * rewrite is reset (i.e. when ARP/ND etnry is gone).
 * NB: the adj being updated may be handling traffic in the DP.
 */
void
adj_nbr_midchain_update_rewrite (adj_index_t adj_index,
				 adj_midchain_fixup_t fixup,
				 adj_midchain_flag_t flags,
				 u8 *rewrite)
{
    vnet_config_main_t * vcm;
    ip_config_main_t *cm;
    ip_adjacency_t *adj;
    u32 ci;

    ASSERT(ADJ_INDEX_INVALID != adj_index);

    adj = adj_get(adj_index);
    adj->lookup_next_index = IP_LOOKUP_NEXT_MIDCHAIN;
    adj->sub_type.midchain.fixup_func = fixup;

    cm = adj_midchain_get_cofing_for_link_type(adj);
    vcm = &(cm->config_main);
    vec_validate_init_empty(cm->config_index_by_sw_if_index,
			    adj->rewrite_header.sw_if_index, ~0);
    ci = cm->config_index_by_sw_if_index[adj->rewrite_header.sw_if_index];

    /*
     * Choose the adj tx function based on whether the client wants
     * to count against the interface or not and insert the appropriate
     * TX feature.
     */
    if (flags & ADJ_MIDCHAIN_FLAG_NO_COUNT)
    {
	adj->sub_type.midchain.tx_function_node =
	    adj_midchain_tx_no_count_node.index;

	ci = vnet_config_add_feature(
		 vlib_get_main(),
		 vcm, ci,
		 adj_midchain_tx_no_count_feature_node[adj->ia_link],
		 /* config data */ 0,
		 /* # bytes of config data */ 0);
    }
    else
    {
	adj->sub_type.midchain.tx_function_node =
	    adj_midchain_tx_node.index;
	ci = vnet_config_add_feature(
		 vlib_get_main(),
		 vcm, ci,
		 adj_midchain_tx_feature_node[adj->ia_link],
		 /* config data */ 0,
		 /* # bytes of config data */ 0);
    }

    cm->config_index_by_sw_if_index[adj->rewrite_header.sw_if_index] = ci;

    if (NULL != rewrite)
    {
	/*
	 * new rewrite provided.
	 * use a dummy rewrite header to get the interface to print into.
	 */
	ip_adjacency_t dummy;
	dpo_id_t tmp = DPO_NULL;

	vnet_rewrite_for_tunnel(vnet_get_main(),
				adj->rewrite_header.sw_if_index,
				adj_get_midchain_node(adj->ia_link),
				adj->sub_type.midchain.tx_function_node,
				&dummy.rewrite_header,
				rewrite,
				vec_len(rewrite));

	/*
	 * this is an update of an existing rewrite.
	 * packets are in flight. we'll need to briefly stack on the drop DPO
	 * whilst the rewrite is written, so any packets that see the partial update
	 * are binned.
	 */
	if (!dpo_id_is_valid(&adj->sub_type.midchain.next_dpo))
	{
	    /*
	     * not stacked yet. stack on the drop
	     */
	    dpo_stack(DPO_ADJACENCY_MIDCHAIN,
		      fib_link_to_dpo_proto(adj->ia_link),
		      &adj->sub_type.midchain.next_dpo,
		      drop_dpo_get(fib_link_to_dpo_proto(adj->ia_link)));
	}

	dpo_copy(&tmp, &adj->sub_type.midchain.next_dpo);
	dpo_stack(DPO_ADJACENCY_MIDCHAIN,
		  fib_link_to_dpo_proto(adj->ia_link),
		  &adj->sub_type.midchain.next_dpo,
		  drop_dpo_get(fib_link_to_dpo_proto(adj->ia_link)));

	CLIB_MEMORY_BARRIER();

	clib_memcpy(&adj->rewrite_header,
		    &dummy.rewrite_header,
		    VLIB_BUFFER_PRE_DATA_SIZE);

	CLIB_MEMORY_BARRIER();

	/*
	 * The graph arc used/created here is from the midchain-tx node to the
	 * child's registered node. This is because post adj processing the next
	 * node are any output features, then the midchain-tx.  from there we
	 * need to get to the stacked child's node.
	 */
	dpo_stack_from_node(adj->sub_type.midchain.tx_function_node,
			    &adj->sub_type.midchain.next_dpo,
			    &tmp);
	dpo_reset(&tmp);
    }
    else
    {
	ASSERT(0);
    }

    /*
     * time for walkies fido.
     */
    fib_node_back_walk_ctx_t bw_ctx = {
	.fnbw_reason = FIB_NODE_BW_REASON_ADJ_UPDATE,
    };

    fib_walk_sync(FIB_NODE_TYPE_ADJ, adj_get_index(adj), &bw_ctx);
}

/**
 * adj_nbr_midchain_unstack
 *
 * Unstack the adj. stack it on drop
 */
void
adj_nbr_midchain_unstack (adj_index_t adj_index)
{
    ip_adjacency_t *adj;

    ASSERT(ADJ_INDEX_INVALID != adj_index);

    adj = adj_get(adj_index);

    /*
     * stack on the drop
     */
    dpo_stack(DPO_ADJACENCY_MIDCHAIN,
	      fib_link_to_dpo_proto(adj->ia_link),
	      &adj->sub_type.midchain.next_dpo,
	      drop_dpo_get(fib_link_to_dpo_proto(adj->ia_link)));

    CLIB_MEMORY_BARRIER();
}

/**
 * adj_nbr_midchain_stack
 */
void
adj_nbr_midchain_stack (adj_index_t adj_index,
			const dpo_id_t *next)
{
    ip_adjacency_t *adj;

    ASSERT(ADJ_INDEX_INVALID != adj_index);

    adj = adj_get(adj_index);

    ASSERT(IP_LOOKUP_NEXT_MIDCHAIN == adj->lookup_next_index);

    dpo_stack_from_node(adj->sub_type.midchain.tx_function_node,
			&adj->sub_type.midchain.next_dpo,
			next);
}

u8*
format_adj_midchain (u8* s, va_list *ap)
{
    index_t index = va_arg(ap, index_t);
    u32 indent = va_arg(ap, u32);
    vnet_main_t * vnm = vnet_get_main();
    ip_adjacency_t * adj = adj_get(index);

    s = format (s, "%U", format_fib_link, adj->ia_link);
    s = format (s, " via %U ",
		format_ip46_address, &adj->sub_type.nbr.next_hop);
    s = format (s, " %U",
		format_vnet_rewrite,
		vnm->vlib_main, &adj->rewrite_header,
		sizeof (adj->rewrite_data), indent);
    s = format (s, "\n%Ustacked-on:\n%U%U",
		format_white_space, indent,
		format_white_space, indent+2,
		format_dpo_id, &adj->sub_type.midchain.next_dpo, indent+2);

    return (s);
}

static void
adj_dpo_lock (dpo_id_t *dpo)
{
    adj_lock(dpo->dpoi_index);
}
static void
adj_dpo_unlock (dpo_id_t *dpo)
{
    adj_unlock(dpo->dpoi_index);
}

const static dpo_vft_t adj_midchain_dpo_vft = {
    .dv_lock = adj_dpo_lock,
    .dv_unlock = adj_dpo_unlock,
    .dv_format = format_adj_midchain,
};

/**
 * @brief The per-protocol VLIB graph nodes that are assigned to a midchain
 *        object.
 *
 * this means that these graph nodes are ones from which a midchain is the
 * parent object in the DPO-graph.
 */
const static char* const midchain_ip4_nodes[] =
{
    "ip4-midchain",
    NULL,
};
const static char* const midchain_ip6_nodes[] =
{
    "ip6-midchain",
    NULL,
};
const static char* const midchain_mpls_nodes[] =
{
    "mpls-midchain",
    NULL,
};
const static char* const midchain_ethernet_nodes[] =
{
    "adj-l2-midchain",
    NULL,
};

const static char* const * const midchain_nodes[DPO_PROTO_NUM] =
{
    [DPO_PROTO_IP4]  = midchain_ip4_nodes,
    [DPO_PROTO_IP6]  = midchain_ip6_nodes,
    [DPO_PROTO_MPLS] = midchain_mpls_nodes,
    [DPO_PROTO_ETHERNET] = midchain_ethernet_nodes,
};

void
adj_midchain_module_init (void)
{
    dpo_register(DPO_ADJACENCY_MIDCHAIN, &adj_midchain_dpo_vft, midchain_nodes);
}