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frr/eigrpd/eigrp_fsm.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* EIGRPd Finite State Machine (DUAL).
* Copyright (C) 2013-2014
* Authors:
* Donnie Savage
* Jan Janovic
* Matej Perina
* Peter Orsag
* Peter Paluch
*
* This file contains functions for executing logic of finite state machine
*
* +------------ +
* | (7) |
* | v
* +=====================================+
* | |
* | Passive |
* | |
* +=====================================+
* ^ | ^ ^ ^ |
* (3)| | (1)| | (1)| |
* | (0)| | (3)| | (2)|
* | | | | | +---------------+
* | | | | | \
* +--------+ | | | +-----------------+ \
* / / / | \ \
* / / / +----+ \ \
* | | | | | |
* | v | | | v
* +===========+ (6) +===========+ +===========+ (6) +===========+
* | |------->| | (5) | |-------->| |
* | | (4) | |------>| | (4) | |
* | ACTIVE 0 |<-------| ACTIVE 1 | | ACTIVE 2 |<--------| ACTIVE 3
* |
* +--| | +--| | +--| | +--| |
* | +===========+ | +===========+ | +===========+ |
* +===========+
* | ^ |(5) | ^ | ^ ^ | ^
* | | +---------|------|------------|----+ | | |
* +-------+ +------+ +---------+ +---------+
* (7) (7) (7) (7)
*
* 0- input event other than query from successor, FC not satisfied
* 1- last reply, FD is reset
* 2- query from successor, FC not satisfied
* 3- last reply, FC satisfied with current value of FDij
* 4- distance increase while in active state
* 5- query from successor while in active state
* 6- last reply, FC not satisfied with current value of FDij
* 7- state not changed, usually by receiving not last reply
*/
#include <zebra.h>
#include "event.h"
#include "prefix.h"
#include "table.h"
#include "memory.h"
#include "log.h"
#include "linklist.h"
#include "vty.h"
#include "eigrpd/eigrp_types.h"
#include "eigrpd/eigrp_structs.h"
#include "eigrpd/eigrpd.h"
#include "eigrpd/eigrp_interface.h"
#include "eigrpd/eigrp_neighbor.h"
#include "eigrpd/eigrp_packet.h"
#include "eigrpd/eigrp_zebra.h"
#include "eigrpd/eigrp_vty.h"
#include "eigrpd/eigrp_network.h"
#include "eigrpd/eigrp_dump.h"
#include "eigrpd/eigrp_topology.h"
#include "eigrpd/eigrp_fsm.h"
#include "eigrpd/eigrp_metric.h"
/*
* Prototypes
*/
int eigrp_fsm_event_keep_state(struct eigrp_fsm_action_message *);
int eigrp_fsm_event_nq_fcn(struct eigrp_fsm_action_message *);
int eigrp_fsm_event_q_fcn(struct eigrp_fsm_action_message *);
int eigrp_fsm_event_lr(struct eigrp_fsm_action_message *);
int eigrp_fsm_event_dinc(struct eigrp_fsm_action_message *);
int eigrp_fsm_event_lr_fcs(struct eigrp_fsm_action_message *);
int eigrp_fsm_event_lr_fcn(struct eigrp_fsm_action_message *);
int eigrp_fsm_event_qact(struct eigrp_fsm_action_message *);
//---------------------------------------------------------------------
/*
* NSM - field of fields of struct containing one function each.
* Which function is used depends on actual state of FSM and occurred
* event(arrow in diagram). Usage:
* NSM[actual/starting state][occurred event].func
* Functions are should be executed within separate thread.
*/
const struct {
int (*func)(struct eigrp_fsm_action_message *);
} NSM[EIGRP_FSM_STATE_MAX][EIGRP_FSM_EVENT_MAX] = {
{
// PASSIVE STATE
{eigrp_fsm_event_nq_fcn}, /* Event 0 */
{eigrp_fsm_event_keep_state}, /* Event 1 */
{eigrp_fsm_event_q_fcn}, /* Event 2 */
{eigrp_fsm_event_keep_state}, /* Event 3 */
{eigrp_fsm_event_keep_state}, /* Event 4 */
{eigrp_fsm_event_keep_state}, /* Event 5 */
{eigrp_fsm_event_keep_state}, /* Event 6 */
{eigrp_fsm_event_keep_state}, /* Event 7 */
},
{
// Active 0 state
{eigrp_fsm_event_keep_state}, /* Event 0 */
{eigrp_fsm_event_keep_state}, /* Event 1 */
{eigrp_fsm_event_keep_state}, /* Event 2 */
{eigrp_fsm_event_lr_fcs}, /* Event 3 */
{eigrp_fsm_event_keep_state}, /* Event 4 */
{eigrp_fsm_event_qact}, /* Event 5 */
{eigrp_fsm_event_lr_fcn}, /* Event 6 */
{eigrp_fsm_event_keep_state}, /* Event 7 */
},
{
// Active 1 state
{eigrp_fsm_event_keep_state}, /* Event 0 */
{eigrp_fsm_event_lr}, /* Event 1 */
{eigrp_fsm_event_keep_state}, /* Event 2 */
{eigrp_fsm_event_keep_state}, /* Event 3 */
{eigrp_fsm_event_dinc}, /* Event 4 */
{eigrp_fsm_event_qact}, /* Event 5 */
{eigrp_fsm_event_keep_state}, /* Event 6 */
{eigrp_fsm_event_keep_state}, /* Event 7 */
},
{
// Active 2 state
{eigrp_fsm_event_keep_state}, /* Event 0 */
{eigrp_fsm_event_keep_state}, /* Event 1 */
{eigrp_fsm_event_keep_state}, /* Event 2 */
{eigrp_fsm_event_lr_fcs}, /* Event 3 */
{eigrp_fsm_event_keep_state}, /* Event 4 */
{eigrp_fsm_event_keep_state}, /* Event 5 */
{eigrp_fsm_event_lr_fcn}, /* Event 6 */
{eigrp_fsm_event_keep_state}, /* Event 7 */
},
{
// Active 3 state
{eigrp_fsm_event_keep_state}, /* Event 0 */
{eigrp_fsm_event_lr}, /* Event 1 */
{eigrp_fsm_event_keep_state}, /* Event 2 */
{eigrp_fsm_event_keep_state}, /* Event 3 */
{eigrp_fsm_event_dinc}, /* Event 4 */
{eigrp_fsm_event_keep_state}, /* Event 5 */
{eigrp_fsm_event_keep_state}, /* Event 6 */
{eigrp_fsm_event_keep_state}, /* Event 7 */
},
};
static const char *packet_type2str(uint8_t packet_type)
{
if (packet_type == EIGRP_OPC_UPDATE)
return "Update";
if (packet_type == EIGRP_OPC_REQUEST)
return "Request";
if (packet_type == EIGRP_OPC_QUERY)
return "Query";
if (packet_type == EIGRP_OPC_REPLY)
return "Reply";
if (packet_type == EIGRP_OPC_HELLO)
return "Hello";
if (packet_type == EIGRP_OPC_IPXSAP)
return "IPXSAP";
if (packet_type == EIGRP_OPC_ACK)
return "Ack";
if (packet_type == EIGRP_OPC_SIAQUERY)
return "SIA Query";
if (packet_type == EIGRP_OPC_SIAREPLY)
return "SIA Reply";
return "Unknown";
}
static const char *prefix_state2str(enum eigrp_fsm_states state)
{
switch (state) {
case EIGRP_FSM_STATE_PASSIVE:
return "Passive";
case EIGRP_FSM_STATE_ACTIVE_0:
return "Active oij0";
case EIGRP_FSM_STATE_ACTIVE_1:
return "Active oij1";
case EIGRP_FSM_STATE_ACTIVE_2:
return "Active oij2";
case EIGRP_FSM_STATE_ACTIVE_3:
return "Active oij3";
}
return "Unknown";
}
static const char *fsm_state2str(enum eigrp_fsm_events event)
{
switch (event) {
case EIGRP_FSM_KEEP_STATE:
return "Keep State Event";
case EIGRP_FSM_EVENT_NQ_FCN:
return "Non Query Event Feasability not satisfied";
case EIGRP_FSM_EVENT_LR:
return "Last Reply Event";
case EIGRP_FSM_EVENT_Q_FCN:
return "Query Event Feasability not satisfied";
case EIGRP_FSM_EVENT_LR_FCS:
return "Last Reply Event Feasability satisfied";
case EIGRP_FSM_EVENT_DINC:
return "Distance Increase Event";
case EIGRP_FSM_EVENT_QACT:
return "Query from Successor while in active state";
case EIGRP_FSM_EVENT_LR_FCN:
return "Last Reply Event, Feasibility not satisfied";
}
return "Unknown";
}
static const char *change2str(enum metric_change change)
{
switch (change) {
case METRIC_DECREASE:
return "Decrease";
case METRIC_SAME:
return "Same";
case METRIC_INCREASE:
return "Increase";
}
return "Unknown";
}
/*
* Main function in which are make decisions which event occurred.
* msg - argument of type struct eigrp_fsm_action_message contain
* details about what happen
*
* Return number of occurred event (arrow in diagram).
*
*/
static enum eigrp_fsm_events
eigrp_get_fsm_event(struct eigrp_fsm_action_message *msg)
{
// Loading base information from message
// struct eigrp *eigrp = msg->eigrp;
struct eigrp_prefix_descriptor *prefix = msg->prefix;
struct eigrp_route_descriptor *entry = msg->entry;
uint8_t actual_state = prefix->state;
enum metric_change change;
if (entry == NULL) {
entry = eigrp_route_descriptor_new();
entry->adv_router = msg->adv_router;
entry->ei = msg->adv_router->ei;
entry->prefix = prefix;
msg->entry = entry;
}
/*
* Calculate resultant metrics and insert to correct position
* in entries list
*/
change = eigrp_topology_update_distance(msg);
/* Store for display later */
msg->change = change;
switch (actual_state) {
case EIGRP_FSM_STATE_PASSIVE: {
struct eigrp_route_descriptor *head =
listnode_head(prefix->entries);
if (head->reported_distance < prefix->fdistance) {
return EIGRP_FSM_KEEP_STATE;
}
/*
* if best entry doesn't satisfy feasibility condition it means
* move to active state
* dependently if it was query from successor
*/
if (msg->packet_type == EIGRP_OPC_QUERY) {
return EIGRP_FSM_EVENT_Q_FCN;
} else {
return EIGRP_FSM_EVENT_NQ_FCN;
}
break;
}
case EIGRP_FSM_STATE_ACTIVE_0: {
if (msg->packet_type == EIGRP_OPC_REPLY) {
struct eigrp_route_descriptor *head =
listnode_head(prefix->entries);
listnode_delete(prefix->rij, entry->adv_router);
if (prefix->rij->count)
return EIGRP_FSM_KEEP_STATE;
zlog_info("All reply received");
if (head->reported_distance < prefix->fdistance) {
return EIGRP_FSM_EVENT_LR_FCS;
}
return EIGRP_FSM_EVENT_LR_FCN;
} else if (msg->packet_type == EIGRP_OPC_QUERY
&& (entry->flags
& EIGRP_ROUTE_DESCRIPTOR_SUCCESSOR_FLAG)) {
return EIGRP_FSM_EVENT_QACT;
}
return EIGRP_FSM_KEEP_STATE;
break;
}
case EIGRP_FSM_STATE_ACTIVE_1: {
if (msg->packet_type == EIGRP_OPC_QUERY
&& (entry->flags & EIGRP_ROUTE_DESCRIPTOR_SUCCESSOR_FLAG)) {
return EIGRP_FSM_EVENT_QACT;
} else if (msg->packet_type == EIGRP_OPC_REPLY) {
listnode_delete(prefix->rij, entry->adv_router);
if (change == METRIC_INCREASE
&& (entry->flags
& EIGRP_ROUTE_DESCRIPTOR_SUCCESSOR_FLAG)) {
return EIGRP_FSM_EVENT_DINC;
} else if (prefix->rij->count) {
return EIGRP_FSM_KEEP_STATE;
} else {
zlog_info("All reply received");
return EIGRP_FSM_EVENT_LR;
}
} else if (msg->packet_type == EIGRP_OPC_UPDATE
&& change == METRIC_INCREASE
&& (entry->flags
& EIGRP_ROUTE_DESCRIPTOR_SUCCESSOR_FLAG)) {
return EIGRP_FSM_EVENT_DINC;
}
return EIGRP_FSM_KEEP_STATE;
break;
}
case EIGRP_FSM_STATE_ACTIVE_2: {
if (msg->packet_type == EIGRP_OPC_REPLY) {
struct eigrp_route_descriptor *head =
listnode_head(prefix->entries);
listnode_delete(prefix->rij, entry->adv_router);
if (prefix->rij->count) {
return EIGRP_FSM_KEEP_STATE;
} else {
zlog_info("All reply received");
if (head->reported_distance
< prefix->fdistance) {
return EIGRP_FSM_EVENT_LR_FCS;
}
return EIGRP_FSM_EVENT_LR_FCN;
}
}
return EIGRP_FSM_KEEP_STATE;
break;
}
case EIGRP_FSM_STATE_ACTIVE_3: {
if (msg->packet_type == EIGRP_OPC_REPLY) {
listnode_delete(prefix->rij, entry->adv_router);
if (change == METRIC_INCREASE
&& (entry->flags
& EIGRP_ROUTE_DESCRIPTOR_SUCCESSOR_FLAG)) {
return EIGRP_FSM_EVENT_DINC;
} else if (prefix->rij->count) {
return EIGRP_FSM_KEEP_STATE;
} else {
zlog_info("All reply received");
return EIGRP_FSM_EVENT_LR;
}
} else if (msg->packet_type == EIGRP_OPC_UPDATE
&& change == METRIC_INCREASE
&& (entry->flags
& EIGRP_ROUTE_DESCRIPTOR_SUCCESSOR_FLAG)) {
return EIGRP_FSM_EVENT_DINC;
}
return EIGRP_FSM_KEEP_STATE;
break;
}
}
return EIGRP_FSM_KEEP_STATE;
}
/*
* Function made to execute in separate thread.
* Load argument from thread and execute proper NSM function
*/
int eigrp_fsm_event(struct eigrp_fsm_action_message *msg)
{
enum eigrp_fsm_events event = eigrp_get_fsm_event(msg);
zlog_info(
"EIGRP AS: %d State: %s Event: %s Network: %pI4 Packet Type: %s Reply RIJ Count: %d change: %s",
msg->eigrp->AS, prefix_state2str(msg->prefix->state),
fsm_state2str(event), &msg->prefix->destination->u.prefix4,
packet_type2str(msg->packet_type), msg->prefix->rij->count,
change2str(msg->change));
(*(NSM[msg->prefix->state][event].func))(msg);
return 1;
}
/*
* Function of event 0.
*
*/
int eigrp_fsm_event_nq_fcn(struct eigrp_fsm_action_message *msg)
{
struct eigrp *eigrp = msg->eigrp;
struct eigrp_prefix_descriptor *prefix = msg->prefix;
struct list *successors = eigrp_topology_get_successor(prefix);
struct eigrp_route_descriptor *ne;
assert(successors); // If this is NULL we have shit the bed, fun huh?
ne = listnode_head(successors);
prefix->state = EIGRP_FSM_STATE_ACTIVE_1;
prefix->rdistance = prefix->distance = prefix->fdistance = ne->distance;
prefix->reported_metric = ne->total_metric;
if (eigrp_nbr_count_get(eigrp)) {
prefix->req_action |= EIGRP_FSM_NEED_QUERY;
listnode_add(eigrp->topology_changes_internalIPV4, prefix);
} else {
eigrp_fsm_event_lr(msg); // in the case that there are no more
// neighbors left
}
list_delete(&successors);
return 1;
}
int eigrp_fsm_event_q_fcn(struct eigrp_fsm_action_message *msg)
{
struct eigrp *eigrp = msg->eigrp;
struct eigrp_prefix_descriptor *prefix = msg->prefix;
struct list *successors = eigrp_topology_get_successor(prefix);
struct eigrp_route_descriptor *ne;
assert(successors); // If this is NULL somebody poked us in the eye.
ne = listnode_head(successors);
prefix->state = EIGRP_FSM_STATE_ACTIVE_3;
prefix->rdistance = prefix->distance = prefix->fdistance = ne->distance;
prefix->reported_metric = ne->total_metric;
if (eigrp_nbr_count_get(eigrp)) {
prefix->req_action |= EIGRP_FSM_NEED_QUERY;
listnode_add(eigrp->topology_changes_internalIPV4, prefix);
} else {
eigrp_fsm_event_lr(msg); // in the case that there are no more
// neighbors left
}
list_delete(&successors);
return 1;
}
int eigrp_fsm_event_keep_state(struct eigrp_fsm_action_message *msg)
{
struct eigrp *eigrp = msg->eigrp;
struct eigrp_prefix_descriptor *prefix = msg->prefix;
struct eigrp_route_descriptor *ne = listnode_head(prefix->entries);
if (prefix->state == EIGRP_FSM_STATE_PASSIVE) {
if (!eigrp_metrics_is_same(prefix->reported_metric,
ne->total_metric)) {
prefix->rdistance = prefix->fdistance =
prefix->distance = ne->distance;
prefix->reported_metric = ne->total_metric;
if (msg->packet_type == EIGRP_OPC_QUERY)
eigrp_send_reply(msg->adv_router, prefix);
prefix->req_action |= EIGRP_FSM_NEED_UPDATE;
listnode_add(eigrp->topology_changes_internalIPV4,
prefix);
}
eigrp_topology_update_node_flags(eigrp, prefix);
eigrp_update_routing_table(eigrp, prefix);
}
if (msg->packet_type == EIGRP_OPC_QUERY)
eigrp_send_reply(msg->adv_router, prefix);
return 1;
}
int eigrp_fsm_event_lr(struct eigrp_fsm_action_message *msg)
{
struct eigrp *eigrp = msg->eigrp;
struct eigrp_prefix_descriptor *prefix = msg->prefix;
struct eigrp_route_descriptor *ne = listnode_head(prefix->entries);
prefix->fdistance = prefix->distance = prefix->rdistance = ne->distance;
prefix->reported_metric = ne->total_metric;
if (prefix->state == EIGRP_FSM_STATE_ACTIVE_3) {
struct list *successors = eigrp_topology_get_successor(prefix);
assert(successors); // It's like Napolean and Waterloo
ne = listnode_head(successors);
eigrp_send_reply(ne->adv_router, prefix);
list_delete(&successors);
}
prefix->state = EIGRP_FSM_STATE_PASSIVE;
prefix->req_action |= EIGRP_FSM_NEED_UPDATE;
listnode_add(eigrp->topology_changes_internalIPV4, prefix);
eigrp_topology_update_node_flags(eigrp, prefix);
eigrp_update_routing_table(eigrp, prefix);
eigrp_update_topology_table_prefix(eigrp, eigrp->topology_table,
prefix);
return 1;
}
int eigrp_fsm_event_dinc(struct eigrp_fsm_action_message *msg)
{
struct list *successors = eigrp_topology_get_successor(msg->prefix);
struct eigrp_route_descriptor *ne;
assert(successors); // Trump and his big hands
ne = listnode_head(successors);
msg->prefix->state = msg->prefix->state == EIGRP_FSM_STATE_ACTIVE_1
? EIGRP_FSM_STATE_ACTIVE_0
: EIGRP_FSM_STATE_ACTIVE_2;
msg->prefix->distance = ne->distance;
if (!msg->prefix->rij->count)
(*(NSM[msg->prefix->state][eigrp_get_fsm_event(msg)].func))(
msg);
list_delete(&successors);
return 1;
}
int eigrp_fsm_event_lr_fcs(struct eigrp_fsm_action_message *msg)
{
struct eigrp *eigrp = msg->eigrp;
struct eigrp_prefix_descriptor *prefix = msg->prefix;
struct eigrp_route_descriptor *ne = listnode_head(prefix->entries);
prefix->state = EIGRP_FSM_STATE_PASSIVE;
prefix->distance = prefix->rdistance = ne->distance;
prefix->reported_metric = ne->total_metric;
prefix->fdistance = prefix->fdistance > prefix->distance
? prefix->distance
: prefix->fdistance;
if (prefix->state == EIGRP_FSM_STATE_ACTIVE_2) {
struct list *successors = eigrp_topology_get_successor(prefix);
assert(successors); // Having a spoon and all you need is a
// knife
ne = listnode_head(successors);
eigrp_send_reply(ne->adv_router, prefix);
list_delete(&successors);
}
prefix->req_action |= EIGRP_FSM_NEED_UPDATE;
listnode_add(eigrp->topology_changes_internalIPV4, prefix);
eigrp_topology_update_node_flags(eigrp, prefix);
eigrp_update_routing_table(eigrp, prefix);
eigrp_update_topology_table_prefix(eigrp, eigrp->topology_table,
prefix);
return 1;
}
int eigrp_fsm_event_lr_fcn(struct eigrp_fsm_action_message *msg)
{
struct eigrp *eigrp = msg->eigrp;
struct eigrp_prefix_descriptor *prefix = msg->prefix;
struct eigrp_route_descriptor *best_successor;
struct list *successors = eigrp_topology_get_successor(prefix);
assert(successors); // Routing without a stack
prefix->state = prefix->state == EIGRP_FSM_STATE_ACTIVE_0
? EIGRP_FSM_STATE_ACTIVE_1
: EIGRP_FSM_STATE_ACTIVE_3;
best_successor = listnode_head(successors);
prefix->rdistance = prefix->distance = best_successor->distance;
prefix->reported_metric = best_successor->total_metric;
if (eigrp_nbr_count_get(eigrp)) {
prefix->req_action |= EIGRP_FSM_NEED_QUERY;
listnode_add(eigrp->topology_changes_internalIPV4, prefix);
} else {
eigrp_fsm_event_lr(msg); // in the case that there are no more
// neighbors left
}
list_delete(&successors);
return 1;
}
int eigrp_fsm_event_qact(struct eigrp_fsm_action_message *msg)
{
struct list *successors = eigrp_topology_get_successor(msg->prefix);
struct eigrp_route_descriptor *ne;
assert(successors); // Cats and no Dogs
ne = listnode_head(successors);
msg->prefix->state = EIGRP_FSM_STATE_ACTIVE_2;
msg->prefix->distance = ne->distance;
list_delete(&successors);
return 1;
}
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