src/vnet/feature/registration.c - fdio/vpp - Gitiles

 /*
  * 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/vnet.h>
 #include <vnet/ip/ip.h>
 #include <vnet/mpls/mpls.h>

 /**
  * @file
  * @brief Feature Subgraph Ordering.

     Dynamically compute feature subgraph ordering by performing a
     topological sort across a set of "feature A before feature B" and
     "feature C after feature B" constraints.

     Use the topological sort result to set up vnet_config_main_t's for
     use at runtime.

     Feature subgraph arcs are simple enough. They start at specific
     fixed nodes, and end at specific fixed nodes.  In between, a
     per-interface current feature configuration dictates which
     additional nodes each packet visits. Each so-called feature node
     can [of course] drop any specific packet.

     See ip4_forward.c, ip6_forward.c in this directory to see the
     current rx-unicast, rx-multicast, and tx feature subgraph arc
     definitions.

     Let's say that we wish to add a new feature to the ip4 unicast
     feature subgraph arc, which needs to run before @c ip4-lookup.  In
     either base code or a plugin,
     <CODE><PRE>
     \#include <vnet/feature/feature.h>
     </PRE></CODE>

     and add the new feature as shown:

     <CODE><PRE>
     VNET_FEATURE_INIT (ip4_lookup, static) =
     {
       .arch_name = "ip4-unicast",
       .node_name = "my-ip4-unicast-feature",
       .runs_before = VLIB_FEATURES ("ip4-lookup")
     };
     </PRE></CODE>

     Here's the standard coding pattern to enable / disable
     @c my-ip4-unicast-feature on an interface:

     <CODE><PRE>

     sw_if_index = <interface-handle>
     vnet_feature_enable_disable ("ip4-unicast", "my-ip4-unicast-feature",
                                  sw_if_index, 1 );
     </PRE></CODE>

     Here's how to obtain the correct next node index in packet
     processing code, aka in the implementation of @c my-ip4-unicast-feature:

     <CODE><PRE>
     vnet_feature_next (sw_if_index0, &next0, b0);

     </PRE></CODE>

     Nodes are free to drop or otherwise redirect packets. Packets
     which "pass" should be enqueued via the next0 arc computed by
     vnet_feature_next.
 */


 static int
 comma_split (u8 * s, u8 ** a, u8 ** b)
 {
   *a = s;

   while (*s && *s != ',')
     s++;

   if (*s == ',')
     *s = 0;
   else
     return 1;

   *b = (u8 *) (s + 1);
   return 0;
 }

 /**
  * @brief Initialize a feature graph arc
  * @param vm vlib main structure pointer
  * @param vcm vnet config main structure pointer
  * @param feature_start_nodes names of start-nodes which use this
  *	  feature graph arc
  * @param num_feature_start_nodes number of start-nodes
  * @param first_reg first element in
  *        [an __attribute__((constructor)) function built, or
  *        otherwise created] singly-linked list of feature registrations
  * @param [out] in_feature_nodes returned vector of
  *        topologically-sorted feature node names, for use in
  *        show commands
  * @returns 0 on success, otherwise an error message. Errors
  *        are fatal since they invariably involve mistyped node-names, or
  *        genuinely missing node-names
  */
 clib_error_t *
 vnet_feature_arc_init (vlib_main_t * vm,
 		       vnet_config_main_t * vcm,
 		       char **feature_start_nodes,
 		       int num_feature_start_nodes,
 		       vnet_feature_registration_t * first_reg,
 		       char ***in_feature_nodes)
 {
   uword *index_by_name;
   uword *reg_by_index;
   u8 **node_names = 0;
   u8 *node_name;
   char **these_constraints;
   char *this_constraint_c;
   u8 **constraints = 0;
   u8 *constraint_tuple;
   u8 *this_constraint;
   u8 **orig, **closure;
   uword *p;
   int i, j, k;
   u8 *a_name, *b_name;
   int a_index, b_index;
   int n_features;
   u32 *result = 0;
   vnet_feature_registration_t *this_reg = 0;
   char **feature_nodes = 0;
   hash_pair_t *hp;
   u8 **keys_to_delete = 0;

   index_by_name = hash_create_string (0, sizeof (uword));
   reg_by_index = hash_create (0, sizeof (uword));

   this_reg = first_reg;

   /* pass 1, collect feature node names, construct a before b pairs */
   while (this_reg)
     {
       node_name = format (0, "%s%c", this_reg->node_name, 0);
       hash_set (reg_by_index, vec_len (node_names), (uword) this_reg);

       hash_set_mem (index_by_name, node_name, vec_len (node_names));

       vec_add1 (node_names, node_name);

       these_constraints = this_reg->runs_before;
       while (these_constraints && these_constraints[0])
 	{
 	  this_constraint_c = these_constraints[0];

 	  constraint_tuple = format (0, "%s,%s%c", node_name,
 				     this_constraint_c, 0);
 	  vec_add1 (constraints, constraint_tuple);
 	  these_constraints++;
 	}

       these_constraints = this_reg->runs_after;
       while (these_constraints && these_constraints[0])
 	{
 	  this_constraint_c = these_constraints[0];

 	  constraint_tuple = format (0, "%s,%s%c",
 				     this_constraint_c, node_name, 0);
 	  vec_add1 (constraints, constraint_tuple);
 	  these_constraints++;
 	}

       this_reg = this_reg->next;
     }

   n_features = vec_len (node_names);
   orig = clib_ptclosure_alloc (n_features);

   for (i = 0; i < vec_len (constraints); i++)
     {
       this_constraint = constraints[i];

       if (comma_split (this_constraint, &a_name, &b_name))
 	return clib_error_return (0, "comma_split failed!");

       p = hash_get_mem (index_by_name, a_name);
       /*
        * Note: the next two errors mean that something is
        * b0rked. As in: if you code "A depends on B," and you forget
        * to define a FEATURE_INIT macro for B, you lose.
        * Nonexistent graph nodes are tolerated.
        */
       if (p == 0)
 	return clib_error_return (0, "feature node '%s' not found", a_name);
       a_index = p[0];

       p = hash_get_mem (index_by_name, b_name);
       if (p == 0)
 	return clib_error_return (0, "feature node '%s' not found", b_name);
       b_index = p[0];

       /* add a before b to the original set of constraints */
       orig[a_index][b_index] = 1;
       vec_free (this_constraint);
     }

   /* Compute the positive transitive closure of the original constraints */
   closure = clib_ptclosure (orig);

   /* Compute a partial order across feature nodes, if one exists. */
 again:
   for (i = 0; i < n_features; i++)
     {
       for (j = 0; j < n_features; j++)
 	{
 	  if (closure[i][j])
 	    goto item_constrained;
 	}
       /* Item i can be output */
       vec_add1 (result, i);
       {
 	for (k = 0; k < n_features; k++)
 	  closure[k][i] = 0;
 	/*
 	 * Add a "Magic" a before a constraint.
 	 * This means we'll never output it again
 	 */
 	closure[i][i] = 1;
 	goto again;
       }
     item_constrained:
       ;
     }

   /* see if we got a partial order... */
   if (vec_len (result) != n_features)
     return clib_error_return (0, "%d feature_init_cast no partial order!");

   /*
    * We win.
    * Bind the index variables, and output the feature node name vector
    * using the partial order we just computed. Result is in stack
    * order, because the entry with the fewest constraints (e.g. none)
    * is output first, etc.
    */

   for (i = n_features - 1; i >= 0; i--)
     {
       p = hash_get (reg_by_index, result[i]);
       ASSERT (p != 0);
       this_reg = (vnet_feature_registration_t *) p[0];
       if (this_reg->feature_index_ptr)
 	*this_reg->feature_index_ptr = n_features - (i + 1);
       this_reg->feature_index = n_features - (i + 1);
       vec_add1 (feature_nodes, this_reg->node_name);
     }

   /* Set up the config infrastructure */
   vnet_config_init (vm, vcm,
 		    feature_start_nodes,
 		    num_feature_start_nodes,
 		    feature_nodes, vec_len (feature_nodes));

   /* Save a copy for show command */
   *in_feature_nodes = feature_nodes;

   /* Finally, clean up all the shit we allocated */
   /* *INDENT-OFF* */
   hash_foreach_pair (hp, index_by_name,
   ({
     vec_add1 (keys_to_delete, (u8 *)hp->key);
   }));
   /* *INDENT-ON* */
   hash_free (index_by_name);
   for (i = 0; i < vec_len (keys_to_delete); i++)
     vec_free (keys_to_delete[i]);
   vec_free (keys_to_delete);
   hash_free (reg_by_index);
   vec_free (result);
   clib_ptclosure_free (orig);
   clib_ptclosure_free (closure);
   return 0;
 }

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* 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/vnet.h>
	#include <vnet/ip/ip.h>
	#include <vnet/mpls/mpls.h>

	/**
	* @file
	* @brief Feature Subgraph Ordering.

	Dynamically compute feature subgraph ordering by performing a
	topological sort across a set of "feature A before feature B" and
	"feature C after feature B" constraints.

	Use the topological sort result to set up vnet_config_main_t's for
	use at runtime.

	Feature subgraph arcs are simple enough. They start at specific
	fixed nodes, and end at specific fixed nodes. In between, a
	per-interface current feature configuration dictates which
	additional nodes each packet visits. Each so-called feature node
	can [of course] drop any specific packet.

	See ip4_forward.c, ip6_forward.c in this directory to see the
	current rx-unicast, rx-multicast, and tx feature subgraph arc
	definitions.

	Let's say that we wish to add a new feature to the ip4 unicast
	feature subgraph arc, which needs to run before @c ip4-lookup. In
	either base code or a plugin,
	<CODE><PRE>
	\#include <vnet/feature/feature.h>
	</PRE></CODE>

	and add the new feature as shown:

	<CODE><PRE>
	VNET_FEATURE_INIT (ip4_lookup, static) =
	{
	.arch_name = "ip4-unicast",
	.node_name = "my-ip4-unicast-feature",
	.runs_before = VLIB_FEATURES ("ip4-lookup")
	};
	</PRE></CODE>

	Here's the standard coding pattern to enable / disable
	@c my-ip4-unicast-feature on an interface:

	<CODE><PRE>

	sw_if_index = <interface-handle>
	vnet_feature_enable_disable ("ip4-unicast", "my-ip4-unicast-feature",
	sw_if_index, 1 );
	</PRE></CODE>

	Here's how to obtain the correct next node index in packet
	processing code, aka in the implementation of @c my-ip4-unicast-feature:

	<CODE><PRE>
	vnet_feature_next (sw_if_index0, &next0, b0);

	</PRE></CODE>

	Nodes are free to drop or otherwise redirect packets. Packets
	which "pass" should be enqueued via the next0 arc computed by
	vnet_feature_next.
	*/


	static int
	comma_split (u8 * s, u8 a, u8 b)
	{
	*a = s;

	while (s && s != ',')
	s++;

	if (*s == ',')
	*s = 0;
	else
	return 1;

	b = (u8 ) (s + 1);
	return 0;
	}

	/**
	* @brief Initialize a feature graph arc
	* @param vm vlib main structure pointer
	* @param vcm vnet config main structure pointer
	* @param feature_start_nodes names of start-nodes which use this
	* feature graph arc
	* @param num_feature_start_nodes number of start-nodes
	* @param first_reg first element in
	* [an __attribute__((constructor)) function built, or
	* otherwise created] singly-linked list of feature registrations
	* @param [out] in_feature_nodes returned vector of
	* topologically-sorted feature node names, for use in
	* show commands
	* @returns 0 on success, otherwise an error message. Errors
	* are fatal since they invariably involve mistyped node-names, or
	* genuinely missing node-names
	*/
	clib_error_t *
	vnet_feature_arc_init (vlib_main_t * vm,
	vnet_config_main_t * vcm,
	char **feature_start_nodes,
	int num_feature_start_nodes,
	vnet_feature_registration_t * first_reg,
	char ***in_feature_nodes)
	{
	uword *index_by_name;
	uword *reg_by_index;
	u8 **node_names = 0;
	u8 *node_name;
	char **these_constraints;
	char *this_constraint_c;
	u8 **constraints = 0;
	u8 *constraint_tuple;
	u8 *this_constraint;
	u8 orig, closure;
	uword *p;
	int i, j, k;
	u8 a_name, b_name;
	int a_index, b_index;
	int n_features;
	u32 *result = 0;
	vnet_feature_registration_t *this_reg = 0;
	char **feature_nodes = 0;
	hash_pair_t *hp;
	u8 **keys_to_delete = 0;

	index_by_name = hash_create_string (0, sizeof (uword));
	reg_by_index = hash_create (0, sizeof (uword));

	this_reg = first_reg;

	/* pass 1, collect feature node names, construct a before b pairs */
	while (this_reg)
	{
	node_name = format (0, "%s%c", this_reg->node_name, 0);
	hash_set (reg_by_index, vec_len (node_names), (uword) this_reg);

	hash_set_mem (index_by_name, node_name, vec_len (node_names));

	vec_add1 (node_names, node_name);

	these_constraints = this_reg->runs_before;
	while (these_constraints && these_constraints[0])
	{
	this_constraint_c = these_constraints[0];

	constraint_tuple = format (0, "%s,%s%c", node_name,
	this_constraint_c, 0);
	vec_add1 (constraints, constraint_tuple);
	these_constraints++;
	}

	these_constraints = this_reg->runs_after;
	while (these_constraints && these_constraints[0])
	{
	this_constraint_c = these_constraints[0];

	constraint_tuple = format (0, "%s,%s%c",
	this_constraint_c, node_name, 0);
	vec_add1 (constraints, constraint_tuple);
	these_constraints++;
	}

	this_reg = this_reg->next;
	}

	n_features = vec_len (node_names);
	orig = clib_ptclosure_alloc (n_features);

	for (i = 0; i < vec_len (constraints); i++)
	{
	this_constraint = constraints[i];

	if (comma_split (this_constraint, &a_name, &b_name))
	return clib_error_return (0, "comma_split failed!");

	p = hash_get_mem (index_by_name, a_name);
	/*
	* Note: the next two errors mean that something is
	* b0rked. As in: if you code "A depends on B," and you forget
	* to define a FEATURE_INIT macro for B, you lose.
	* Nonexistent graph nodes are tolerated.
	*/
	if (p == 0)
	return clib_error_return (0, "feature node '%s' not found", a_name);
	a_index = p[0];

	p = hash_get_mem (index_by_name, b_name);
	if (p == 0)
	return clib_error_return (0, "feature node '%s' not found", b_name);
	b_index = p[0];

	/* add a before b to the original set of constraints */
	orig[a_index][b_index] = 1;
	vec_free (this_constraint);
	}

	/* Compute the positive transitive closure of the original constraints */
	closure = clib_ptclosure (orig);

	/* Compute a partial order across feature nodes, if one exists. */
	again:
	for (i = 0; i < n_features; i++)
	{
	for (j = 0; j < n_features; j++)
	{
	if (closure[i][j])
	goto item_constrained;
	}
	/* Item i can be output */
	vec_add1 (result, i);
	{
	for (k = 0; k < n_features; k++)
	closure[k][i] = 0;
	/*
	* Add a "Magic" a before a constraint.
	* This means we'll never output it again
	*/
	closure[i][i] = 1;
	goto again;
	}
	item_constrained:
	;
	}

	/* see if we got a partial order... */
	if (vec_len (result) != n_features)
	return clib_error_return (0, "%d feature_init_cast no partial order!");

	/*
	* We win.
	* Bind the index variables, and output the feature node name vector
	* using the partial order we just computed. Result is in stack
	* order, because the entry with the fewest constraints (e.g. none)
	* is output first, etc.
	*/

	for (i = n_features - 1; i >= 0; i--)
	{
	p = hash_get (reg_by_index, result[i]);
	ASSERT (p != 0);
	this_reg = (vnet_feature_registration_t *) p[0];
	if (this_reg->feature_index_ptr)
	*this_reg->feature_index_ptr = n_features - (i + 1);
	this_reg->feature_index = n_features - (i + 1);
	vec_add1 (feature_nodes, this_reg->node_name);
	}

	/* Set up the config infrastructure */
	vnet_config_init (vm, vcm,
	feature_start_nodes,
	num_feature_start_nodes,
	feature_nodes, vec_len (feature_nodes));

	/* Save a copy for show command */
	*in_feature_nodes = feature_nodes;

	/* Finally, clean up all the shit we allocated */
	/* INDENT-OFF */
	hash_foreach_pair (hp, index_by_name,
	({
	vec_add1 (keys_to_delete, (u8 *)hp->key);
	}));
	/* INDENT-ON */
	hash_free (index_by_name);
	for (i = 0; i < vec_len (keys_to_delete); i++)
	vec_free (keys_to_delete[i]);
	vec_free (keys_to_delete);
	hash_free (reg_by_index);
	vec_free (result);
	clib_ptclosure_free (orig);
	clib_ptclosure_free (closure);
	return 0;
	}

	/*
	* fd.io coding-style-patch-verification: ON
	*
	* Local Variables:
	* eval: (c-set-style "gnu")
	* End:
	*/