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Diffstat (limited to 'src/vnet/feature/registration.c')
| -rw-r--r-- | src/vnet/feature/registration.c | 301 |
1 files changed, 301 insertions, 0 deletions
diff --git a/src/vnet/feature/registration.c b/src/vnet/feature/registration.c new file mode 100644 index 00000000000..1deeeef904c --- /dev/null +++ b/src/vnet/feature/registration.c @@ -0,0 +1,301 @@ +/* + * 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: + */ |