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180 | // Copyright (C) 2022-2024 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#include <config.h>
#include <dhcpsrv/random_allocator.h>
#include <dhcpsrv/subnet.h>
#include <algorithm><--- Include file: not found. Please note: Cppcheck does not need standard library headers to get proper results.
#include <random><--- Include file: not found. Please note: Cppcheck does not need standard library headers to get proper results.
using namespace isc::asiolink;
using namespace std;
namespace isc {
namespace dhcp {
RandomAllocator::RandomAllocator(Lease::Type type, const WeakSubnetPtr& subnet)
: Allocator(type, subnet), generator_() {
random_device rd;
generator_.seed(rd());
}
IOAddress
RandomAllocator::pickAddressInternal(const ClientClasses& client_classes,
const IdentifierBaseTypePtr&,
const IOAddress&) {
auto subnet = subnet_.lock();
auto const& pools = subnet->getPools(pool_type_);
// Let's first iterate over the pools and identify the ones that
// meet client class criteria. Then, segregate these pools into
// the ones that still have available addresses and exhausted
// ones.
std::vector<uint64_t> available;
std::vector<uint64_t> exhausted;
for (auto i = 0; i < pools.size(); ++i) {
// Check if the pool is allowed for the client's classes.
if (pools[i]->clientSupported(client_classes)) {
// Get or create the pool state.
auto state = getPoolState(pools[i]);
if (state->getPermutation()->exhausted()) {
// Pool is exhausted. It means that all addresses from
// this pool have been offered. It doesn't mean that
// leases are allocated for all these addresses. It
// only means that all have been picked from the pool.
exhausted.push_back(i);
} else {
// There are still available addresses in this pool. It
// means that not all of them have been offered.
available.push_back(i);
}
}
}
// Find a suitable pool.
PoolPtr pool;
if (!available.empty()) {
// There are pools with available addresses. Let's randomly
// pick one of these pools and get next available address.
pool = pools[available[getRandomNumber(available.size() - 1)]];
} else if (!exhausted.empty()) {
// All pools have been exhausted. We will start offering the same
// addresses from these pools. We need to reset the permutations
// of the exhausted pools.
for (auto const& e : exhausted) {
getPoolState(pools[e])->getPermutation()->reset();
}
// Get random pool from those we just reset.
pool = pools[exhausted[getRandomNumber(exhausted.size() - 1)]];
}
// If pool has been found, let's get next address.
if (pool) {
auto done = false;
return (getPoolState(pool)->getPermutation()->next(done));
}
// No pool available. There are no pools or client classes do
// not match.
return (pool_type_ == Lease::TYPE_V4 ? IOAddress::IPV4_ZERO_ADDRESS() : IOAddress::IPV6_ZERO_ADDRESS());
}
IOAddress
RandomAllocator::pickPrefixInternal(const ClientClasses& client_classes,
Pool6Ptr& pool6,
const IdentifierBaseTypePtr&,
PrefixLenMatchType prefix_length_match,
const IOAddress&,
uint8_t hint_prefix_length) {
auto subnet = subnet_.lock();
auto const& pools = subnet->getPools(pool_type_);
// Let's first iterate over the pools and identify the ones that
// meet client class criteria. Then, segragate these pools into
// the ones that still have available addresses and exhausted
// ones.
std::vector<uint64_t> available;
std::vector<uint64_t> exhausted;
for (auto i = 0; i < pools.size(); ++i) {
// Check if the pool is allowed for the client's classes.
if (pools[i]->clientSupported(client_classes)) {
if (!Allocator::isValidPrefixPool(prefix_length_match, pools[i],
hint_prefix_length)) {
continue;
}
// Get or create the pool state.
auto state = getPoolState(pools[i]);
if (state->getPermutation()->exhausted()) {
// Pool is exhausted. It means that all prefixes from
// this pool have been offered. It doesn't mean that
// leases are allocated for all these prefixes. It
// only means that all have been picked from the pool.
exhausted.push_back(i);
} else {
// There are still available prefixes in this pool. It
// means that not all of them have been offered.
available.push_back(i);
}
}
}
// Find a suitable pool.
PoolPtr pool;
if (!available.empty()) {
// There are pools with available prefixes. Let's randomly
// pick one of these pools and get next available prefix.
pool = pools[available[getRandomNumber(available.size() - 1)]];
} else if (!exhausted.empty()) {
// All pools have been exhausted. We will start offering the same
// prefixes from these pools. We need to reset the permutations
// of the exhausted pools.
for (auto const& e : exhausted) {
getPoolState(pools[e])->getPermutation()->reset();
}
// Get random pool from those we just reset.
pool = pools[exhausted[getRandomNumber(exhausted.size() - 1)]];
}
// If pool has been found, let's get next prefix.
if (pool) {
auto done = false;
pool6 = boost::dynamic_pointer_cast<Pool6>(pool);
if (!pool6) {
// Something is gravely wrong here
isc_throw(Unexpected, "Wrong type of pool: "
<< (pool)->toText()
<< " is not Pool6");
}
return (getPoolState(pool)->getPermutation()->next(done));
}
// No pool available. There are no pools or client classes do
// not match.
return (IOAddress::IPV6_ZERO_ADDRESS());
}
PoolRandomAllocationStatePtr
RandomAllocator::getPoolState(const PoolPtr& pool) const {
if (!pool->getAllocationState()) {
pool->setAllocationState(PoolRandomAllocationState::create(pool));
}
return (boost::dynamic_pointer_cast<PoolRandomAllocationState>(pool->getAllocationState()));
}
uint64_t
RandomAllocator::getRandomNumber(uint64_t limit) {
// Take the short path if there is only one number to randomize from.
if (limit == 0) {
return 0;
}
std::uniform_int_distribution<uint64_t> dist(0, limit);
return (dist(generator_));
}
} // end of namespace isc::dhcp
} // end of namespace isc
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