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lib: skip route-map optimization if !AF_INET(6)
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Currently we unconditionally send a prefix through the optimized
route-map codepath if the v4 and v6 LPM tables have been allocated and
optimization has not been disabled.
However prefixes from address-families that are not IPv4/IPv6 unicast
always fail the optimized route-map index lookup, because they occur on
an LPM tree that is IPv4 or IPv6 specific.
e.g.
Even if you have an empty permit route-map clause, Type-3 EVPN routes
are always denied:
```
--config
route-map soo-foo permit 10

--logs
2023/02/17 19:38:42 BGP: [KZK58-6T4Y6] No best match sequence for pfx: [3]:[0]:[32]:[2.2.2.2] in route-map: soo-foo, result: no match
2023/02/17 19:38:42 BGP: [H5AW4-JFYQC] Route-map: soo-foo, prefix: [3]:[0]:[32]:[2.2.2.2], result: deny
```

There is some existing code that creates an AF_INET/AF_INET6 prefix
using the IP/prefix information from a Type-2/5 EVPN route, which
allowed only these two route-types to successfully attempt an LPM lookup
in the route-map optimization trees via the converted prefix.

This commit does 3 things:
1) Reverts to non-optimized route-map lookup for prefixes that are not
   AF_INET or AF_INET6.
2) Cleans up the route-map code so that the AF check is part of the
   index lookup + the EVPN RT-2/5 -> AF_INET/6 prefix conversion occurs
   outside the index lookup.
3) Adds "debug route-map detail" logs to indicate when we attempt to
   convert an AF_EVPN prefix into an AF_INET/6 prefix + when we fallback
   to a non-optimized lookup.

Additional functionality for optimized lookups of prefixes from other
address-families can be added prior to the index lookup, similar to how
the existing EVPN conversion works today.

New behavior:
```
2023/02/17 21:44:27 BGP: [WYP1M-NE4SY] Converted EVPN prefix [5]:[0]:[32]:[192.0.2.7] into 192.0.2.7/32 for optimized route-map lookup
2023/02/17 21:44:27 BGP: [MT1SJ-WEJQ1] Best match route-map: soo-foo, sequence: 10 for pfx: 192.0.2.7/32, result: match
2023/02/17 21:44:27 BGP: [H5AW4-JFYQC] Route-map: soo-foo, prefix: 192.0.2.7/32, result: permit

2023/02/17 21:44:27 BGP: [WYP1M-NE4SY] Converted EVPN prefix [2]:[0]:[48]:[aa:bb:cc:00:22:22]:[32]:[20.0.0.2] into 20.0.0.2/32 for optimized route-map lookup
2023/02/17 21:44:27 BGP: [MT1SJ-WEJQ1] Best match route-map: soo-foo, sequence: 10 for pfx: 20.0.0.2/32, result: match
2023/02/17 21:44:27 BGP: [H5AW4-JFYQC] Route-map: soo-foo, prefix: 20.0.0.2/32, result: permit

2023/02/17 21:44:27 BGP: [KHG7H-RH4PN] Unable to convert EVPN prefix [3]:[0]:[32]:[2.2.2.2] into IPv4/IPv6 prefix. Falling back to non-optimized route-map lookup
2023/02/17 21:44:27 BGP: [MT1SJ-WEJQ1] Best match route-map: soo-foo, sequence: 10 for pfx: [3]:[0]:[32]:[2.2.2.2], result: match
2023/02/17 21:44:27 BGP: [H5AW4-JFYQC] Route-map: soo-foo, prefix: [3]:[0]:[32]:[2.2.2.2], result: permit
```

Signed-off-by: Trey Aspelund <taspelund@nvidia.com>
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@ton31337
Trey Aspelund authored and ton31337 committed Jul 25, 2023
1 parent d156e44 commit 7603eca
Showing 1 changed file with 56 additions and 43 deletions.
99 changes: 56 additions & 43 deletions lib/routemap.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1817,26 +1817,24 @@ route_map_get_index(struct route_map *map, const struct prefix *prefix,
struct route_map_index *index = NULL, *best_index = NULL;
struct route_map_index *head_index = NULL;
struct route_table *table = NULL;
struct prefix conv;
unsigned char family;

/*
* Handling for matching evpn_routes in the prefix table.
*
* We convert type2/5 prefix to ipv4/6 prefix to do longest
* prefix matching on.
/* Route-map optimization relies on LPM lookups of the prefix to reduce
* the amount of route-map clauses a given prefix needs to be processed
* against. These LPM trees are IPv4/IPv6-specific and prefix->family
* must be AF_INET or AF_INET6 in order for the lookup to succeed. So if
* the AF doesn't line up with the LPM trees, skip the optimization.
*/
if (prefix->family == AF_EVPN) {
if (evpn_prefix2prefix(prefix, &conv) != 0)
return NULL;

prefix = &conv;
if (map->optimization_disabled ||
(prefix->family == AF_INET && !map->ipv4_prefix_table) ||
(prefix->family == AF_INET6 && !map->ipv6_prefix_table)) {
if (rmap_debug)
zlog_debug(
"Skipping route-map optimization for route-map: %s, pfx: %pFX, family: %d",
map->name, prefix, prefix->family);
return map->head;
}


family = prefix->family;

if (family == AF_INET)
if (prefix->family == AF_INET)
table = map->ipv4_prefix_table;
else
table = map->ipv6_prefix_table;
Expand Down Expand Up @@ -2558,6 +2556,7 @@ route_map_result_t route_map_apply_ext(struct route_map *map,
struct route_map_index *index = NULL;
struct route_map_rule *set = NULL;
bool skip_match_clause = false;
struct prefix conv;

if (recursion > RMAP_RECURSION_LIMIT) {
flog_warn(
Expand All @@ -2575,37 +2574,51 @@ route_map_result_t route_map_apply_ext(struct route_map *map,

map->applied++;

if ((!map->optimization_disabled)
&& (map->ipv4_prefix_table || map->ipv6_prefix_table)) {
index = route_map_get_index(map, prefix, match_object,
&match_ret);
if (index) {
index->applied++;
if (rmap_debug)
zlog_debug(
"Best match route-map: %s, sequence: %d for pfx: %pFX, result: %s",
map->name, index->pref, prefix,
route_map_cmd_result_str(match_ret));
/*
* Handling for matching evpn_routes in the prefix table.
*
* We convert type2/5 prefix to ipv4/6 prefix to do longest
* prefix matching on.
*/
if (prefix->family == AF_EVPN) {
if (evpn_prefix2prefix(prefix, &conv) != 0) {
zlog_debug(
"Unable to convert EVPN prefix %pFX into IPv4/IPv6 prefix. Falling back to non-optimized route-map lookup",
prefix);
} else {
if (rmap_debug)
zlog_debug(
"No best match sequence for pfx: %pFX in route-map: %s, result: %s",
prefix, map->name,
route_map_cmd_result_str(match_ret));
/*
* No index matches this prefix. Return deny unless,
* match_ret = RMAP_NOOP.
*/
if (match_ret == RMAP_NOOP)
ret = RMAP_PERMITMATCH;
else
ret = RMAP_DENYMATCH;
goto route_map_apply_end;
zlog_debug(
"Converted EVPN prefix %pFX into %pFX for optimized route-map lookup",
prefix, &conv);

prefix = &conv;
}
skip_match_clause = true;
}

index = route_map_get_index(map, prefix, match_object, &match_ret);
if (index) {
index->applied++;
if (rmap_debug)
zlog_debug(
"Best match route-map: %s, sequence: %d for pfx: %pFX, result: %s",
map->name, index->pref, prefix,
route_map_cmd_result_str(match_ret));
} else {
index = map->head;
if (rmap_debug)
zlog_debug(
"No best match sequence for pfx: %pFX in route-map: %s, result: %s",
prefix, map->name,
route_map_cmd_result_str(match_ret));
/*
* No index matches this prefix. Return deny unless,
* match_ret = RMAP_NOOP.
*/
if (match_ret == RMAP_NOOP)
ret = RMAP_PERMITMATCH;
else
ret = RMAP_DENYMATCH;
goto route_map_apply_end;
}
skip_match_clause = true;

for (; index; index = index->next) {
if (!skip_match_clause) {
Expand Down

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