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network: dhcp6pd: introduce a simplified and unified method to calculate subnet prefix

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This commit is contained in:
Yu Watanabe
2021-10-26 00:35:22 +09:00
parent f595b2e9b4
commit 56bbe0ef02
1 changed files with 42 additions and 33 deletions
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src/network/networkd-dhcp6.c
+42 -33
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@@ -457,74 +457,83 @@ static bool link_has_preferred_subnet_id(Link *link) {
return link->network->dhcp6_pd_subnet_id >= 0;
}
static int dhcp6_get_preferred_delegated_prefix(
static int dhcp6_pd_calculate_prefix(
const struct in6_addr *pd_prefix,
uint8_t pd_prefix_len,
uint64_t subnet_id,
struct in6_addr *ret) {
struct in6_addr prefix;
assert(pd_prefix);
assert(pd_prefix_len <= 64);
assert(ret);
if (subnet_id >= UINT64_C(1) << (64 - pd_prefix_len))
return -ERANGE;
prefix = *pd_prefix;
if (pd_prefix_len < 32)
prefix.s6_addr32[0] |= htobe32(subnet_id >> 32);
prefix.s6_addr32[1] |= htobe32(subnet_id & 0xffffffff);
*ret = prefix;
return 0;
}
static int dhcp6_pd_get_preferred_prefix(
Link *link,
const struct in6_addr *pd_prefix,
uint8_t pd_prefix_len,
struct in6_addr *ret) {
/* We start off with the original PD prefix we have been assigned and iterate from there */
union in_addr_union prefix;
uint64_t n_prefixes;
struct in6_addr prefix;
Link *assigned_link;
int r;
assert(link);
assert(link->manager);
assert(pd_prefix);
assert(pd_prefix_len <= 64);
n_prefixes = UINT64_C(1) << (64 - pd_prefix_len);
prefix.in6 = *pd_prefix;
if (link_has_preferred_subnet_id(link)) {
uint64_t subnet_id = link->network->dhcp6_pd_subnet_id;
/* If the link has a preference for a particular subnet id try to allocate that */
if (subnet_id >= n_prefixes)
return log_link_warning_errno(link, SYNTHETIC_ERRNO(ERANGE),
"subnet id %" PRIu64 " is out of range. Only have %" PRIu64 " subnets.",
subnet_id, n_prefixes);
r = in_addr_prefix_nth(AF_INET6, &prefix, 64, subnet_id);
r = dhcp6_pd_calculate_prefix(pd_prefix, pd_prefix_len, link->network->dhcp6_pd_subnet_id, &prefix);
if (r < 0)
return log_link_warning_errno(link, r,
"subnet id %" PRIu64 " is out of range. Only have %" PRIu64 " subnets.",
subnet_id, n_prefixes);
link->network->dhcp6_pd_subnet_id, UINT64_C(1) << (64 - pd_prefix_len));
/* Verify that the prefix we did calculate fits in the pd prefix.
* This should not fail as we checked the prefix size beforehand */
assert_se(in6_addr_prefix_covers(pd_prefix, pd_prefix_len, &prefix.in6) > 0);
if (link_get_by_dhcp6_pd_prefix(link->manager, &prefix.in6, &assigned_link) >= 0 &&
if (link_get_by_dhcp6_pd_prefix(link->manager, &prefix, &assigned_link) >= 0 &&
assigned_link != link) {
_cleanup_free_ char *assigned_buf = NULL;
(void) in6_addr_to_string(&prefix.in6, &assigned_buf);
(void) in6_addr_to_string(&prefix, &assigned_buf);
return log_link_warning_errno(link, SYNTHETIC_ERRNO(EAGAIN),
"The requested prefix %s is already assigned to another link.",
strna(assigned_buf));
}
*ret = prefix.in6;
*ret = prefix;
return 0;
}
for (uint64_t n = 0; n < n_prefixes; n++) {
for (uint64_t n = 0; ; n++) {
r = dhcp6_pd_calculate_prefix(pd_prefix, pd_prefix_len, n, &prefix);
if (r < 0)
return log_link_warning_errno(link, r,
"Couldn't find a suitable prefix. Ran out of address space.");
/* If we do not have an allocation preference just iterate
* through the address space and return the first free prefix. */
if (link_get_by_dhcp6_pd_prefix(link->manager, &prefix.in6, &assigned_link) < 0 ||
if (link_get_by_dhcp6_pd_prefix(link->manager, &prefix, &assigned_link) < 0 ||
assigned_link == link) {
*ret = prefix.in6;
*ret = prefix;
return 0;
}
r = in_addr_prefix_next(AF_INET6, &prefix, 64);
if (r < 0)
return log_link_warning_errno(link, r, "Can't allocate another prefix. Out of address space?: %m");
}
return log_link_warning_errno(link, SYNTHETIC_ERRNO(ERANGE), "Couldn't find a suitable prefix. Ran out of address space.");
}
static int dhcp6_pd_prefix_distribute(
@@ -560,7 +569,7 @@ static int dhcp6_pd_prefix_distribute(
continue;
if (dhcp6_pd_get_assigned_prefix(link, pd_prefix, pd_prefix_len, &assigned_prefix) < 0 &&
dhcp6_get_preferred_delegated_prefix(link, pd_prefix, pd_prefix_len, &assigned_prefix) < 0)
dhcp6_pd_get_preferred_prefix(link, pd_prefix, pd_prefix_len, &assigned_prefix) < 0)
continue;
(void) in6_addr_prefix_to_string(&assigned_prefix, 64, &buf);