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ospf_ti_lfa.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* OSPF TI-LFA
* Copyright (C) 2020 NetDEF, Inc.
* Sascha Kattelmann
*/
#include <zebra.h>
#include "prefix.h"
#include "table.h"
#include "printfrr.h"
#include "ospfd/ospfd.h"
#include "ospfd/ospf_asbr.h"
#include "ospfd/ospf_lsa.h"
#include "ospfd/ospf_spf.h"
#include "ospfd/ospf_sr.h"
#include "ospfd/ospf_route.h"
#include "ospfd/ospf_ti_lfa.h"
#include "ospfd/ospf_dump.h"
DECLARE_RBTREE_UNIQ(p_spaces, struct p_space, p_spaces_item,
p_spaces_compare_func);
DECLARE_RBTREE_UNIQ(q_spaces, struct q_space, q_spaces_item,
q_spaces_compare_func);
static void
ospf_ti_lfa_generate_p_space(struct ospf_area *area, struct vertex *child,
struct protected_resource *protected_resource,
bool recursive, struct list *pc_path);
void ospf_print_protected_resource(
struct protected_resource *protected_resource, char *buf)
{
struct router_lsa_link *link;
switch (protected_resource->type) {
case OSPF_TI_LFA_LINK_PROTECTION:
link = protected_resource->link;
snprintfrr(buf, PROTECTED_RESOURCE_STRLEN,
"protected link: %pI4 %pI4", &link->link_id,
&link->link_data);
break;
case OSPF_TI_LFA_NODE_PROTECTION:
snprintfrr(buf, PROTECTED_RESOURCE_STRLEN,
"protected node: %pI4",
&protected_resource->router_id);
break;
case OSPF_TI_LFA_UNDEFINED_PROTECTION:
snprintfrr(buf, PROTECTED_RESOURCE_STRLEN,
"undefined protected resource");
break;
}
}
static enum ospf_ti_lfa_p_q_space_adjacency
ospf_ti_lfa_find_p_node(struct vertex *pc_node, struct p_space *p_space,
struct q_space *q_space)
{
struct listnode *curr_node;
struct vertex *p_node = NULL, *pc_node_parent, *p_node_pc_parent;
struct vertex_parent *pc_vertex_parent;
curr_node = listnode_lookup(q_space->pc_path, pc_node);
assert(curr_node);
pc_node_parent = listgetdata(curr_node->next);
q_space->p_node_info->type = OSPF_TI_LFA_UNDEFINED_NODE;
p_node = ospf_spf_vertex_find(pc_node_parent->id, p_space->vertex_list);
if (p_node) {
q_space->p_node_info->node = p_node;
q_space->p_node_info->type = OSPF_TI_LFA_P_NODE;
if (curr_node->next->next) {
p_node_pc_parent = listgetdata(curr_node->next->next);
pc_vertex_parent = ospf_spf_vertex_parent_find(
p_node_pc_parent->id, pc_node_parent);
q_space->p_node_info->nexthop =
pc_vertex_parent->nexthop->router;
} else {
/*
* It can happen that the P node is the root node itself
* (hence there can be no parents). In this case we
* don't need to set a nexthop.
*/
q_space->p_node_info->nexthop.s_addr = INADDR_ANY;
}
return OSPF_TI_LFA_P_Q_SPACE_ADJACENT;
}
ospf_ti_lfa_find_p_node(pc_node_parent, p_space, q_space);
return OSPF_TI_LFA_P_Q_SPACE_NON_ADJACENT;
}
static void ospf_ti_lfa_find_q_node(struct vertex *pc_node,
struct p_space *p_space,
struct q_space *q_space)
{
struct listnode *curr_node, *next_node;
struct vertex *p_node, *q_node, *q_space_parent = NULL, *pc_node_parent;
struct vertex_parent *pc_vertex_parent;
curr_node = listnode_lookup(q_space->pc_path, pc_node);
assert(curr_node);
next_node = curr_node->next;
pc_node_parent = listgetdata(next_node);
pc_vertex_parent =
ospf_spf_vertex_parent_find(pc_node_parent->id, pc_node);
p_node = ospf_spf_vertex_find(pc_node->id, p_space->vertex_list);
q_node = ospf_spf_vertex_find(pc_node->id, q_space->vertex_list);
/* The Q node is always present. */
assert(q_node);
q_space->q_node_info->type = OSPF_TI_LFA_UNDEFINED_NODE;
if (p_node && q_node) {
q_space->q_node_info->node = pc_node;
q_space->q_node_info->type = OSPF_TI_LFA_PQ_NODE;
q_space->q_node_info->nexthop =
pc_vertex_parent->nexthop->router;
return;
}
/*
* Note that the Q space has the 'reverse' direction of the PC
* SPF. Hence compare PC SPF parent to Q space children.
*/
q_space_parent =
ospf_spf_vertex_find(pc_node_parent->id, q_node->children);
/*
* If the Q space parent doesn't exist we 'hit' the border to the P
* space and hence got our Q node.
*/
if (!q_space_parent) {
q_space->q_node_info->node = pc_node;
q_space->q_node_info->type = OSPF_TI_LFA_Q_NODE;
q_space->q_node_info->nexthop =
pc_vertex_parent->nexthop->router;
return;
}
return ospf_ti_lfa_find_q_node(pc_node_parent, p_space, q_space);
}
static void ospf_ti_lfa_append_label_stack(struct mpls_label_stack *label_stack,
mpls_label_t labels[],
uint32_t num_labels)
{
int i, offset, limit;
limit = label_stack->num_labels + num_labels;
offset = label_stack->num_labels;
for (i = label_stack->num_labels; i < limit; i++) {
label_stack->label[i] = labels[i - offset];
label_stack->num_labels++;
}
}
static struct mpls_label_stack *
ospf_ti_lfa_create_label_stack(mpls_label_t labels[], uint32_t num_labels)
{
struct mpls_label_stack *label_stack;
uint32_t i;
/* Sanity check */
for (i = 0; i < num_labels; i++) {
if (labels[i] == MPLS_INVALID_LABEL)
return NULL;
}
label_stack = XCALLOC(MTYPE_OSPF_Q_SPACE,
sizeof(struct mpls_label_stack)
+ MPLS_MAX_LABELS * sizeof(mpls_label_t));
label_stack->num_labels = num_labels;
for (i = 0; i < num_labels; i++)
label_stack->label[i] = labels[i];
return label_stack;
}
static struct list *
ospf_ti_lfa_map_path_to_pc_vertices(struct list *path,
struct list *pc_vertex_list)
{
struct listnode *node;
struct vertex *vertex, *pc_vertex;
struct list *pc_path;
pc_path = list_new();
for (ALL_LIST_ELEMENTS_RO(path, node, vertex)) {
pc_vertex = ospf_spf_vertex_find(vertex->id, pc_vertex_list);
listnode_add(pc_path, pc_vertex);
}
return pc_path;
}
static struct list *ospf_ti_lfa_cut_out_pc_path(struct list *pc_vertex_list,
struct list *pc_path,
struct vertex *p_node,
struct vertex *q_node)
{
struct list *inner_pc_path;
struct vertex *current_vertex;
struct listnode *current_listnode;
inner_pc_path = list_new();
current_vertex = ospf_spf_vertex_find(q_node->id, pc_vertex_list);
current_listnode = listnode_lookup(pc_path, current_vertex);
/* Note that the post-convergence paths are reversed. */
while (current_listnode) {
current_vertex = listgetdata(current_listnode);
listnode_add(inner_pc_path, current_vertex);
if (current_vertex->id.s_addr == p_node->id.s_addr)
break;
current_listnode = current_listnode->next;
}
return inner_pc_path;
}
static void ospf_ti_lfa_generate_inner_label_stack(
struct ospf_area *area, struct p_space *p_space,
struct q_space *q_space,
struct ospf_ti_lfa_inner_backup_path_info *inner_backup_path_info)
{
struct route_table *new_table;
struct vertex *q_node;
struct vertex *start_vertex, *end_vertex;
struct vertex_parent *vertex_parent;
struct listnode *pc_p_node, *pc_q_node;
struct vertex *spf_orig;
struct list *vertex_list_orig;
struct p_spaces_head *p_spaces_orig;
struct p_space *inner_p_space;
struct q_space *inner_q_space;
struct ospf_ti_lfa_node_info *p_node_info, *q_node_info;
struct protected_resource *protected_resource;
struct list *inner_pc_path;
mpls_label_t start_label, end_label;
p_node_info = q_space->p_node_info;
q_node_info = q_space->q_node_info;
protected_resource = p_space->protected_resource;
start_vertex = p_node_info->node;
end_vertex = q_node_info->node;
/*
* It can happen that the P node and/or the Q node are the root or
* the destination, therefore we need to force one step forward (resp.
* backward) using an Adjacency-SID.
*/
start_label = MPLS_INVALID_LABEL;
end_label = MPLS_INVALID_LABEL;
if (p_node_info->node->id.s_addr == p_space->root->id.s_addr) {
pc_p_node = listnode_lookup(q_space->pc_path, p_space->pc_spf);
assert(pc_p_node);
start_vertex = listgetdata(pc_p_node->prev);
start_label = ospf_sr_get_adj_sid_by_id(&p_node_info->node->id,
&start_vertex->id);
}
if (q_node_info->node->id.s_addr == q_space->root->id.s_addr) {
pc_q_node = listnode_lookup(q_space->pc_path,
listnode_head(q_space->pc_path));
assert(pc_q_node);
end_vertex = listgetdata(pc_q_node->next);
end_label = ospf_sr_get_adj_sid_by_id(&end_vertex->id,
&q_node_info->node->id);
}
/* Corner case: inner path is just one node */
if (start_vertex->id.s_addr == end_vertex->id.s_addr) {
inner_backup_path_info->label_stack =
ospf_ti_lfa_create_label_stack(&start_label, 1);
inner_backup_path_info->q_node_info.node = end_vertex;
inner_backup_path_info->q_node_info.type = OSPF_TI_LFA_PQ_NODE;
inner_backup_path_info->p_node_info.type =
OSPF_TI_LFA_UNDEFINED_NODE;
vertex_parent = ospf_spf_vertex_parent_find(p_space->root->id,
end_vertex);
inner_backup_path_info->p_node_info.nexthop =
vertex_parent->nexthop->router;
return;
}
inner_pc_path = ospf_ti_lfa_cut_out_pc_path(p_space->pc_vertex_list,
q_space->pc_path,
start_vertex, end_vertex);
new_table = route_table_init();
/* Copy the current state ... */
spf_orig = area->spf;
vertex_list_orig = area->spf_vertex_list;
p_spaces_orig = area->p_spaces;
area->p_spaces =
XCALLOC(MTYPE_OSPF_P_SPACE, sizeof(struct p_spaces_head));
/* dry run true, root node false */
ospf_spf_calculate(area, start_vertex->lsa_p, new_table, NULL, NULL,
true, false);
q_node = ospf_spf_vertex_find(end_vertex->id, area->spf_vertex_list);
ospf_ti_lfa_generate_p_space(area, q_node, protected_resource, false,
inner_pc_path);
/* There's just one P and Q space */
inner_p_space = p_spaces_pop(area->p_spaces);
inner_q_space = q_spaces_pop(inner_p_space->q_spaces);
/* Copy over inner backup path information from the inner q_space */
/* In case the outer P node is also the root of the P space */
if (start_label != MPLS_INVALID_LABEL) {
inner_backup_path_info->label_stack =
ospf_ti_lfa_create_label_stack(&start_label, 1);
ospf_ti_lfa_append_label_stack(
inner_backup_path_info->label_stack,
inner_q_space->label_stack->label,
inner_q_space->label_stack->num_labels);
inner_backup_path_info->p_node_info.node = start_vertex;
inner_backup_path_info->p_node_info.type = OSPF_TI_LFA_P_NODE;
vertex_parent = ospf_spf_vertex_parent_find(p_space->root->id,
start_vertex);
inner_backup_path_info->p_node_info.nexthop =
vertex_parent->nexthop->router;
} else {
memcpy(inner_backup_path_info->label_stack,
inner_q_space->label_stack,
sizeof(struct mpls_label_stack)
+ sizeof(mpls_label_t)
* inner_q_space->label_stack
->num_labels);
memcpy(&inner_backup_path_info->p_node_info,
inner_q_space->p_node_info,
sizeof(struct ospf_ti_lfa_node_info));
}
/* In case the outer Q node is also the root of the Q space */
if (end_label != MPLS_INVALID_LABEL) {
inner_backup_path_info->q_node_info.node = end_vertex;
inner_backup_path_info->q_node_info.type = OSPF_TI_LFA_Q_NODE;
} else {
memcpy(&inner_backup_path_info->q_node_info,
inner_q_space->q_node_info,
sizeof(struct ospf_ti_lfa_node_info));
}
/* Cleanup */
ospf_ti_lfa_free_p_spaces(area);
ospf_spf_cleanup(area->spf, area->spf_vertex_list);
/* ... and copy the current state back. */
area->spf = spf_orig;
area->spf_vertex_list = vertex_list_orig;
area->p_spaces = p_spaces_orig;
}
static void ospf_ti_lfa_generate_label_stack(struct ospf_area *area,
struct p_space *p_space,
struct q_space *q_space)
{
enum ospf_ti_lfa_p_q_space_adjacency adjacency_result;
mpls_label_t labels[MPLS_MAX_LABELS];
struct vertex *pc_node;
struct ospf_ti_lfa_inner_backup_path_info inner_backup_path_info;
if (IS_DEBUG_OSPF_TI_LFA)
zlog_debug(
"%s: Generating Label stack for src %pI4 and dest %pI4.",
__func__, &p_space->root->id, &q_space->root->id);
pc_node = listnode_head(q_space->pc_path);
if (!pc_node) {
if (IS_DEBUG_OSPF_TI_LFA)
zlog_debug(
"%s: There seems to be no post convergence path (yet).",
__func__);
return;
}
ospf_ti_lfa_find_q_node(pc_node, p_space, q_space);
if (q_space->q_node_info->type == OSPF_TI_LFA_UNDEFINED_NODE) {
if (IS_DEBUG_OSPF_TI_LFA)
zlog_debug("%s: Q node not found!", __func__);
return;
}
/* Found a PQ node? Then we are done here. */
if (q_space->q_node_info->type == OSPF_TI_LFA_PQ_NODE) {
/*
* If the PQ node is a child of the root, then we can use an
* adjacency SID instead of a prefix SID for the backup path.
*/
if (ospf_spf_vertex_parent_find(p_space->root->id,
q_space->q_node_info->node))
labels[0] = ospf_sr_get_adj_sid_by_id(
&p_space->root->id,
&q_space->q_node_info->node->id);
else
labels[0] = ospf_sr_get_prefix_sid_by_id(
&q_space->q_node_info->node->id);
q_space->label_stack =
ospf_ti_lfa_create_label_stack(labels, 1);
q_space->nexthop = q_space->q_node_info->nexthop;
return;
}
/* Otherwise find a (hopefully adjacent) P node. */
pc_node = ospf_spf_vertex_find(q_space->q_node_info->node->id,
p_space->pc_vertex_list);
adjacency_result = ospf_ti_lfa_find_p_node(pc_node, p_space, q_space);
if (q_space->p_node_info->type == OSPF_TI_LFA_UNDEFINED_NODE) {
if (IS_DEBUG_OSPF_TI_LFA)
zlog_debug("%s: P node not found!", __func__);
return;
}
/*
* This should be the regular case: P and Q space are adjacent or even
* overlapping. This is guaranteed for link protection when used with
* symmetric weights.
*/
if (adjacency_result == OSPF_TI_LFA_P_Q_SPACE_ADJACENT) {
/*
* It can happen that the P node is the root itself, therefore
* we don't need a label for it. So just one adjacency SID for
* the Q node.
*/
if (q_space->p_node_info->node->id.s_addr
== p_space->root->id.s_addr) {
labels[0] = ospf_sr_get_adj_sid_by_id(
&p_space->root->id,
&q_space->q_node_info->node->id);
q_space->label_stack =
ospf_ti_lfa_create_label_stack(labels, 1);
q_space->nexthop = q_space->q_node_info->nexthop;
return;
}
/*
* Otherwise we have a P and also a Q node (which are adjacent).
*
* It can happen that the P node is a child of the root,
* therefore we might just need the adjacency SID for the P node
* instead of the prefix SID. For the Q node always take the
* adjacency SID.
*/
if (ospf_spf_vertex_parent_find(p_space->root->id,
q_space->p_node_info->node))
labels[0] = ospf_sr_get_adj_sid_by_id(
&p_space->root->id,
&q_space->p_node_info->node->id);
else
labels[0] = ospf_sr_get_prefix_sid_by_id(
&q_space->p_node_info->node->id);
labels[1] = ospf_sr_get_adj_sid_by_id(
&q_space->p_node_info->node->id,
&q_space->q_node_info->node->id);
q_space->label_stack =
ospf_ti_lfa_create_label_stack(labels, 2);
q_space->nexthop = q_space->p_node_info->nexthop;
} else {
/*
* It can happen that the P and Q space are not adjacent when
* e.g. node protection or asymmetric weights are used. In this
* case the found P and Q nodes are used as a reference for
* another run of the algorithm!
*
* After having found the inner label stack it is stitched
* together with the outer labels.
*/
inner_backup_path_info.label_stack = XCALLOC(
MTYPE_OSPF_PATH,
sizeof(struct mpls_label_stack)
+ sizeof(mpls_label_t) * MPLS_MAX_LABELS);
ospf_ti_lfa_generate_inner_label_stack(area, p_space, q_space,
&inner_backup_path_info);
/*
* First stitch together the outer P node label with the inner
* label stack.
*/
if (q_space->p_node_info->node->id.s_addr
== p_space->root->id.s_addr) {
/*
* It can happen that the P node is the root itself,
* therefore we don't need a label for it. Just take
* the inner label stack first.
*/
q_space->label_stack = ospf_ti_lfa_create_label_stack(
inner_backup_path_info.label_stack->label,
inner_backup_path_info.label_stack->num_labels);
/* Use the inner P or Q node for the nexthop */
if (inner_backup_path_info.p_node_info.type
!= OSPF_TI_LFA_UNDEFINED_NODE)
q_space->nexthop = inner_backup_path_info
.p_node_info.nexthop;
else
q_space->nexthop = inner_backup_path_info
.q_node_info.nexthop;
} else if (ospf_spf_vertex_parent_find(
p_space->root->id,
q_space->p_node_info->node)) {
/*
* It can happen that the outer P node is a child of
* the root, therefore we might just need the
* adjacency SID for the outer P node instead of the
* prefix SID. Then just append the inner label stack.
*/
labels[0] = ospf_sr_get_adj_sid_by_id(
&p_space->root->id,
&q_space->p_node_info->node->id);
q_space->label_stack =
ospf_ti_lfa_create_label_stack(labels, 1);
ospf_ti_lfa_append_label_stack(
q_space->label_stack,
inner_backup_path_info.label_stack->label,
inner_backup_path_info.label_stack->num_labels);
q_space->nexthop = q_space->p_node_info->nexthop;
} else {
/* The outer P node needs a Prefix-SID here */
labels[0] = ospf_sr_get_prefix_sid_by_id(
&q_space->p_node_info->node->id);
q_space->label_stack =
ospf_ti_lfa_create_label_stack(labels, 1);
ospf_ti_lfa_append_label_stack(
q_space->label_stack,
inner_backup_path_info.label_stack->label,
inner_backup_path_info.label_stack->num_labels);
q_space->nexthop = q_space->p_node_info->nexthop;
}
/* Now the outer Q node needs to be considered */
if (ospf_spf_vertex_parent_find(
inner_backup_path_info.q_node_info.node->id,
q_space->q_node_info->node)) {
/*
* The outer Q node can be a child of the inner Q node,
* hence just add an Adjacency-SID.
*/
labels[0] = ospf_sr_get_adj_sid_by_id(
&inner_backup_path_info.q_node_info.node->id,
&q_space->q_node_info->node->id);
ospf_ti_lfa_append_label_stack(q_space->label_stack,
labels, 1);
} else {
/* Otherwise a Prefix-SID is needed */
labels[0] = ospf_sr_get_prefix_sid_by_id(
&q_space->q_node_info->node->id);
ospf_ti_lfa_append_label_stack(q_space->label_stack,
labels, 1);
}
/*
* Note that there's also the case where the inner and outer Q
* node are the same, but then there's nothing to do!
*/
}
}
static struct list *
ospf_ti_lfa_generate_post_convergence_path(struct list *pc_vertex_list,
struct vertex *dest)
{
struct list *pc_path;
struct vertex *current_vertex;
struct vertex_parent *parent;
current_vertex = ospf_spf_vertex_find(dest->id, pc_vertex_list);
if (!current_vertex) {
if (IS_DEBUG_OSPF_TI_LFA)
zlog_debug(
"%s: There seems to be no post convergence path (yet).",
__func__);
return NULL;
}
pc_path = list_new();
listnode_add(pc_path, current_vertex);
/* Generate a backup path in reverse order */
for (;;) {
parent = listnode_head(current_vertex->parents);
if (!parent)
break;
listnode_add(pc_path, parent->parent);
current_vertex = parent->parent;
}
return pc_path;
}
static void ospf_ti_lfa_generate_q_spaces(struct ospf_area *area,
struct p_space *p_space,
struct vertex *dest, bool recursive,
struct list *pc_path)
{
struct listnode *node;
struct vertex *child;
struct route_table *new_table;
struct q_space *q_space, q_space_search;
char label_buf[MPLS_LABEL_STRLEN];
char res_buf[PROTECTED_RESOURCE_STRLEN];
bool node_protected;
ospf_print_protected_resource(p_space->protected_resource, res_buf);
node_protected =
p_space->protected_resource->type == OSPF_TI_LFA_NODE_PROTECTION
&& dest->id.s_addr
== p_space->protected_resource->router_id.s_addr;
/*
* If node protection is used, don't build a Q space for the protected
* node of that particular P space. Move on with children instead.
*/
if (node_protected) {
if (recursive) {
/* Recursively generate Q spaces for all children */
for (ALL_LIST_ELEMENTS_RO(dest->children, node, child))
ospf_ti_lfa_generate_q_spaces(area, p_space,
child, recursive,
pc_path);
}
return;
}
/* Check if we already have a Q space for this destination */
q_space_search.root = dest;
if (q_spaces_find(p_space->q_spaces, &q_space_search))
return;
q_space = XCALLOC(MTYPE_OSPF_Q_SPACE, sizeof(struct q_space));
q_space->p_node_info = XCALLOC(MTYPE_OSPF_Q_SPACE,
sizeof(struct ospf_ti_lfa_node_info));
q_space->q_node_info = XCALLOC(MTYPE_OSPF_Q_SPACE,
sizeof(struct ospf_ti_lfa_node_info));
new_table = route_table_init();
/*
* Generate a new (reversed!) SPF tree for this vertex,
* dry run true, root node false
*/
area->spf_reversed = true;
ospf_spf_calculate(area, dest->lsa_p, new_table, NULL, NULL, true,
false);
/* Reset the flag for reverse SPF */
area->spf_reversed = false;
q_space->root = area->spf;
q_space->vertex_list = area->spf_vertex_list;
q_space->label_stack = NULL;
if (pc_path)
q_space->pc_path = ospf_ti_lfa_map_path_to_pc_vertices(
pc_path, p_space->pc_vertex_list);
else
q_space->pc_path = ospf_ti_lfa_generate_post_convergence_path(
p_space->pc_vertex_list, q_space->root);
/* If there's no backup path available then we are done here. */
if (!q_space->pc_path) {
zlog_info(
"%s: NO backup path found for root %pI4 and destination %pI4 for %s, aborting ...",
__func__, &p_space->root->id, &q_space->root->id,
res_buf);
list_delete(&q_space->vertex_list);
XFREE(MTYPE_OSPF_Q_SPACE, q_space->p_node_info);
XFREE(MTYPE_OSPF_Q_SPACE, q_space->q_node_info);
XFREE(MTYPE_OSPF_Q_SPACE, q_space);
return;
}
/* 'Cut' the protected resource out of the new SPF tree */
ospf_spf_remove_resource(q_space->root, q_space->vertex_list,
p_space->protected_resource);
/*
* Generate the smallest possible label stack from the root of the P
* space to the root of the Q space.
*/
ospf_ti_lfa_generate_label_stack(area, p_space, q_space);
if (q_space->label_stack) {
mpls_label2str(q_space->label_stack->num_labels,
q_space->label_stack->label, label_buf,
MPLS_LABEL_STRLEN, 0, true);
zlog_info(
"%s: Generated label stack %s for root %pI4 and destination %pI4 for %s",
__func__, label_buf, &p_space->root->id,
&q_space->root->id, res_buf);
} else {
zlog_info(
"%s: NO label stack generated for root %pI4 and destination %pI4 for %s",
__func__, &p_space->root->id, &q_space->root->id,
res_buf);
}
/* We are finished, store the new Q space in the P space struct */
q_spaces_add(p_space->q_spaces, q_space);
/* Recursively generate Q spaces for all children */
if (recursive) {
for (ALL_LIST_ELEMENTS_RO(dest->children, node, child))
ospf_ti_lfa_generate_q_spaces(area, p_space, child,
recursive, pc_path);
}
}
static void ospf_ti_lfa_generate_post_convergence_spf(struct ospf_area *area,
struct p_space *p_space)
{
struct route_table *new_table;
new_table = route_table_init();
area->spf_protected_resource = p_space->protected_resource;
/*
* The 'post convergence' SPF tree is generated here
* dry run true, root node false
*
* So how does this work? During the SPF calculation the algorithm
* checks if a link belongs to a protected resource and then just
* ignores it.
* This is actually _NOT_ a good way to calculate the post
* convergence SPF tree. The preferred way would be to delete the
* relevant links (and nodes) from a copy of the LSDB and then just run
* the SPF algorithm on that as usual.
* However, removing links from router LSAs appears to be its own
* endeavour (because LSAs are stored as a 'raw' stream), so we go with
* this rather hacky way for now.
*/
ospf_spf_calculate(area, area->router_lsa_self, new_table, NULL, NULL,
true, false);
p_space->pc_spf = area->spf;
p_space->pc_vertex_list = area->spf_vertex_list;
area->spf_protected_resource = NULL;
}
static void
ospf_ti_lfa_generate_p_space(struct ospf_area *area, struct vertex *child,
struct protected_resource *protected_resource,
bool recursive, struct list *pc_path)
{
struct vertex *spf_orig;
struct list *vertex_list, *vertex_list_orig;
struct p_space *p_space;
p_space = XCALLOC(MTYPE_OSPF_P_SPACE, sizeof(struct p_space));
vertex_list = list_new();
/* The P-space will get its own SPF tree, so copy the old one */
ospf_spf_copy(area->spf, vertex_list);
p_space->root = listnode_head(vertex_list);
p_space->vertex_list = vertex_list;
p_space->protected_resource = protected_resource;
/* Initialize the Q spaces for this P space and protected resource */
p_space->q_spaces =
XCALLOC(MTYPE_OSPF_Q_SPACE, sizeof(struct q_spaces_head));
q_spaces_init(p_space->q_spaces);
/* 'Cut' the protected resource out of the new SPF tree */
ospf_spf_remove_resource(p_space->root, p_space->vertex_list,
p_space->protected_resource);
/*
* Since we are going to calculate more SPF trees for Q spaces, keep the
* 'original' one here temporarily
*/
spf_orig = area->spf;
vertex_list_orig = area->spf_vertex_list;
/* Generate the post convergence SPF as a blueprint for backup paths */
ospf_ti_lfa_generate_post_convergence_spf(area, p_space);
/* Generate the relevant Q spaces for this particular P space */
ospf_ti_lfa_generate_q_spaces(area, p_space, child, recursive, pc_path);
/* Put the 'original' SPF tree back in place */
area->spf = spf_orig;
area->spf_vertex_list = vertex_list_orig;
/* We are finished, store the new P space */
p_spaces_add(area->p_spaces, p_space);
}
void ospf_ti_lfa_generate_p_spaces(struct ospf_area *area,
enum protection_type protection_type)
{
struct listnode *node, *inner_node;
struct vertex *root, *child;
struct vertex_parent *vertex_parent;
uint8_t *p, *lim;
struct router_lsa_link *l = NULL;
struct prefix stub_prefix, child_prefix;
struct protected_resource *protected_resource;
area->p_spaces =
XCALLOC(MTYPE_OSPF_P_SPACE, sizeof(struct p_spaces_head));
p_spaces_init(area->p_spaces);
root = area->spf;
/* Root or its router LSA was not created yet? */
if (!root || !root->lsa)
return;
stub_prefix.family = AF_INET;
child_prefix.family = AF_INET;
child_prefix.prefixlen = IPV4_MAX_BITLEN;
p = ((uint8_t *)root->lsa) + OSPF_LSA_HEADER_SIZE + 4;
lim = ((uint8_t *)root->lsa) + ntohs(root->lsa->length);
zlog_info("%s: Generating P spaces for area %pI4", __func__,
&area->area_id);
/*
* Iterate over all stub networks which target other OSPF neighbors.
* Check the nexthop of the child vertex if a stub network is relevant.
*/
while (p < lim) {
l = (struct router_lsa_link *)p;
p += (OSPF_ROUTER_LSA_LINK_SIZE
+ (l->m[0].tos_count * OSPF_ROUTER_LSA_TOS_SIZE));
/* First comes node protection */
if (protection_type == OSPF_TI_LFA_NODE_PROTECTION) {
if (l->m[0].type == LSA_LINK_TYPE_POINTOPOINT) {
protected_resource = XCALLOC(
MTYPE_OSPF_P_SPACE,
sizeof(struct protected_resource));
protected_resource->type = protection_type;
protected_resource->router_id = l->link_id;
child = ospf_spf_vertex_find(
protected_resource->router_id,
root->children);
if (child)
ospf_ti_lfa_generate_p_space(
area, child, protected_resource,
true, NULL);
}
continue;
}
/* The rest is about link protection */
if (protection_type != OSPF_TI_LFA_LINK_PROTECTION)
continue;
if (l->m[0].type != LSA_LINK_TYPE_STUB)
continue;
stub_prefix.prefixlen = ip_masklen(l->link_data);
stub_prefix.u.prefix4 = l->link_id;
for (ALL_LIST_ELEMENTS_RO(root->children, node, child)) {
if (child->type != OSPF_VERTEX_ROUTER)
continue;
for (ALL_LIST_ELEMENTS_RO(child->parents, inner_node,
vertex_parent)) {
child_prefix.u.prefix4 =
vertex_parent->nexthop->router;
/*
* If there's a link for that stub network then
* we will protect it. Hence generate a P space
* for that particular link including the
* Q spaces so we can later on generate a
* backup path for the link.
*/
if (prefix_match(&stub_prefix, &child_prefix)) {
zlog_info(
"%s: Generating P space for %pI4",
__func__, &l->link_id);
protected_resource = XCALLOC(
MTYPE_OSPF_P_SPACE,
sizeof(struct
protected_resource));
protected_resource->type =
protection_type;
protected_resource->link = l;
ospf_ti_lfa_generate_p_space(
area, child, protected_resource,
true, NULL);
}
}
}
}
}
static struct p_space *ospf_ti_lfa_get_p_space_by_path(struct ospf_area *area,
struct ospf_path *path)
{
struct p_space *p_space;
struct router_lsa_link *link;
struct vertex *child;
int type;
frr_each(p_spaces, area->p_spaces, p_space) {
type = p_space->protected_resource->type;
if (type == OSPF_TI_LFA_LINK_PROTECTION) {
link = p_space->protected_resource->link;
if ((path->nexthop.s_addr & link->link_data.s_addr)
== (link->link_id.s_addr & link->link_data.s_addr))
return p_space;
}
if (type == OSPF_TI_LFA_NODE_PROTECTION) {
child = ospf_spf_vertex_by_nexthop(area->spf,
&path->nexthop);
if (child
&& p_space->protected_resource->router_id.s_addr
== child->id.s_addr)
return p_space;
}
}
return NULL;
}
void ospf_ti_lfa_insert_backup_paths(struct ospf_area *area,
struct route_table *new_table)
{
struct route_node *rn;
struct ospf_route *or;
struct ospf_path *path;
struct listnode *node;
struct p_space *p_space;
struct q_space *q_space, q_space_search;
struct vertex root_search;
char label_buf[MPLS_LABEL_STRLEN];
for (rn = route_top(new_table); rn; rn = route_next(rn)) {
or = rn->info;
if (or == NULL)
continue;
/* Insert a backup path for all OSPF paths */
for (ALL_LIST_ELEMENTS_RO(or->paths, node, path)) {
if (path->adv_router.s_addr == INADDR_ANY
|| path->nexthop.s_addr == INADDR_ANY)
continue;
if (IS_DEBUG_OSPF_TI_LFA)
zlog_debug(
"%s: attempting to insert backup path for prefix %pFX, router id %pI4 and nexthop %pI4.",
__func__, &rn->p, &path->adv_router,
&path->nexthop);
p_space = ospf_ti_lfa_get_p_space_by_path(area, path);
if (!p_space) {
if (IS_DEBUG_OSPF_TI_LFA)
zlog_debug(
"%s: P space not found for router id %pI4 and nexthop %pI4.",
__func__, &path->adv_router,
&path->nexthop);
continue;