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network: dhcp6: manage assigned downstream prefixes by using Hashmap

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When a system has thousands of downstream interfaces, previously the
total cost of finding free subnet ID was O(n^2), where n is the number
of downstream interfaces.

This makes assigned prefixes are managed by Manager with Hashmap. So,
the cost becomes O(n log n).
This commit is contained in:
Yu Watanabe 2021-10-14 03:10:31 +09:00
parent 3f3bc1f2e7
commit cde09c3450
3 changed files with 56 additions and 47 deletions
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101
src/network/networkd-dhcp6.c
View File

@ -56,51 +56,53 @@ static bool dhcp6_lease_has_pd_prefix(sd_dhcp6_lease *lease) {
return sd_dhcp6_lease_get_pd(lease, &pd_prefix, &pd_prefix_len, &lifetime_preferred, &lifetime_valid) >= 0;
}
static int dhcp6_pd_get_link_by_prefix(Manager *manager, const struct in6_addr *prefix, Link **ret) {
union in_addr_union u;
static void link_remove_dhcp6_pd_prefix(Link *link, const struct in6_addr *prefix) {
void *key;
assert(link);
assert(link->manager);
assert(prefix);
if (hashmap_get(link->manager->links_by_dhcp6_pd_prefix, prefix) != link)
return;
hashmap_remove2(link->manager->links_by_dhcp6_pd_prefix, prefix, &key);
free(key);
}
static int link_add_dhcp6_pd_prefix(Link *link, const struct in6_addr *prefix) {
_cleanup_free_ struct in6_addr *copy = NULL;
int r;
assert(link);
assert(prefix);
copy = newdup(struct in6_addr, prefix, 1);
if (!copy)
return -ENOMEM;
r = hashmap_ensure_put(&link->manager->links_by_dhcp6_pd_prefix, &in6_addr_hash_ops_free, copy, link);
if (r < 0)
return r;
if (r > 0)
TAKE_PTR(copy);
return 0;
}
static int link_get_by_dhcp6_pd_prefix(Manager *manager, const struct in6_addr *prefix, Link **ret) {
Link *link;
assert(manager);
assert(prefix);
u.in6 = *prefix;
link = hashmap_get(manager->links_by_dhcp6_pd_prefix, prefix);
if (!link)
return -ENODEV;
HASHMAP_FOREACH(link, manager->links_by_index) {
if (!link_dhcp6_pd_is_enabled(link))
continue;
if (link->network->dhcp6_pd_assign) {
Address *address;
SET_FOREACH(address, link->addresses) {
if (address->source != NETWORK_CONFIG_SOURCE_DHCP6PD)
continue;
assert(address->family == AF_INET6);
if (in_addr_prefix_covers(AF_INET6, &u, 64, &address->in_addr) > 0) {
if (ret)
*ret = link;
return 0;
}
}
} else {
Route *route;
SET_FOREACH(route, link->routes) {
if (route->source != NETWORK_CONFIG_SOURCE_DHCP6PD)
continue;
assert(route->family == AF_INET6);
if (in6_addr_equal(&route->dst.in6, prefix)) {
if (ret)
*ret = link;
return 0;
}
}
}
}
return -ENOENT;
if (ret)
*ret = link;
return 0;
}
static int dhcp6_pd_get_assigned_prefix(Link *link, const struct in6_addr *pd_prefix, uint8_t pd_prefix_len, struct in6_addr *ret) {
@ -175,6 +177,8 @@ int dhcp6_pd_remove(Link *link, bool only_marked) {
if (link->radv)
(void) sd_radv_remove_prefix(link->radv, &route->dst.in6, 64);
link_remove_dhcp6_pd_prefix(link, &route->dst.in6);
k = route_remove(route);
if (k < 0)
r = k;
@ -183,17 +187,20 @@ int dhcp6_pd_remove(Link *link, bool only_marked) {
}
SET_FOREACH(address, link->addresses) {
struct in6_addr prefix;
if (address->source != NETWORK_CONFIG_SOURCE_DHCP6PD)
continue;
if (only_marked && !address_is_marked(address))
continue;
if (link->radv) {
union in_addr_union prefix = address->in_addr;
prefix = address->in_addr.in6;
in6_addr_mask(&prefix, 64);
in_addr_mask(AF_INET6, &prefix, 64);
(void) sd_radv_remove_prefix(link->radv, &prefix.in6, 64);
}
if (link->radv)
(void) sd_radv_remove_prefix(link->radv, &prefix, 64);
link_remove_dhcp6_pd_prefix(link, &prefix);
k = address_remove(address);
if (k < 0)
@ -436,7 +443,7 @@ static int dhcp6_pd_assign_prefix(
if (r < 0)
return r;
return 0;
return link_add_dhcp6_pd_prefix(link, prefix);
}
static bool link_has_preferred_subnet_id(Link *link) {
@ -485,7 +492,7 @@ static int dhcp6_get_preferred_delegated_prefix(
* This should not fail as we checked the prefix size beforehand */
assert_se(in_addr_prefix_covers(AF_INET6, (const union in_addr_union*) pd_prefix, pd_prefix_len, &prefix) > 0);
if (dhcp6_pd_get_link_by_prefix(link->manager, &prefix.in6, &assigned_link) >= 0 &&
if (link_get_by_dhcp6_pd_prefix(link->manager, &prefix.in6, &assigned_link) >= 0 &&
assigned_link != link) {
_cleanup_free_ char *assigned_buf = NULL;
@ -502,7 +509,7 @@ static int dhcp6_get_preferred_delegated_prefix(
for (uint64_t n = 0; n < n_prefixes; n++) {
/* If we do not have an allocation preference just iterate
* through the address space and return the first free prefix. */
if (dhcp6_pd_get_link_by_prefix(link->manager, &prefix.in6, &assigned_link) < 0 ||
if (link_get_by_dhcp6_pd_prefix(link->manager, &prefix.in6, &assigned_link) < 0 ||
assigned_link == link) {
*ret = prefix.in6;
return 0;

1
src/network/networkd-manager.c
View File

@ -485,6 +485,7 @@ Manager* manager_free(Manager *m) {
m->dirty_links = set_free_with_destructor(m->dirty_links, link_unref);
m->links_by_name = hashmap_free(m->links_by_name);
m->links_by_hw_addr = hashmap_free(m->links_by_hw_addr);
m->links_by_dhcp6_pd_prefix = hashmap_free(m->links_by_dhcp6_pd_prefix);
m->links_by_index = hashmap_free_with_destructor(m->links_by_index, link_unref);
m->networks = ordered_hashmap_free_with_destructor(m->networks, network_unref);

1
src/network/networkd-manager.h
View File

@ -48,6 +48,7 @@ struct Manager {
Hashmap *links_by_index;
Hashmap *links_by_name;
Hashmap *links_by_hw_addr;
Hashmap *links_by_dhcp6_pd_prefix;
Hashmap *netdevs;
OrderedHashmap *networks;
OrderedSet *address_pools;