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// Copyright (C) 2020-2021 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 <dhcp6/client_handler.h>
#include <dhcp6/dhcp6_log.h>
#include <exceptions/exceptions.h>
#include <stats/stats_mgr.h>
#include <util/multi_threading_mgr.h>
using namespace std;
using namespace isc::util;
using namespace isc::log;
namespace isc {
namespace dhcp {
ClientHandler::Client::Client(Pkt6Ptr query, DuidPtr client_id)
: query_(query), thread_(this_thread::get_id()) {
// Sanity checks.
if (!query) {
isc_throw(InvalidParameter, "null query in ClientHandler");
}
if (!client_id) {
isc_throw(InvalidParameter, "null client-id in ClientHandler");
}
duid_ = client_id->getDuid();
}
mutex ClientHandler::mutex_;
ClientHandler::ClientContainer ClientHandler::clients_;
ClientHandler::ClientPtr
ClientHandler::lookup(const DuidPtr& duid) {
// Sanity check.
if (!duid) {
isc_throw(InvalidParameter, "null duid in ClientHandler::lookup");
}
auto it = clients_.find(duid->getDuid());
if (it == clients_.end()) {
return (ClientPtr());
}
return (*it);
}
void
ClientHandler::add(const ClientPtr& client) {
// Sanity check.
if (!client) {
isc_throw(InvalidParameter, "null client in ClientHandler::add");
}
// Assume insert will never fail so not checking its result.
clients_.insert(client);
}
void
ClientHandler::del(const DuidPtr& duid) {
// Sanity check.
if (!duid) {
isc_throw(InvalidParameter, "null duid in ClientHandler::del");
}
// Assume erase will never fail so not checking its result.
clients_.erase(duid->getDuid());
}
ClientHandler::ClientHandler() : client_(), locked_() {
}
ClientHandler::~ClientHandler() {
if (locked_) {
lock_guard<mutex> lk(mutex_);
unLock();
}
}
bool
ClientHandler::tryLock(Pkt6Ptr query, ContinuationPtr cont) {
// Sanity checks.
if (!query) {
isc_throw(InvalidParameter, "null query in ClientHandler::tryLock");
}
if (locked_) {
isc_throw(Unexpected, "already handling in ClientHandler::tryLock");
}
const DuidPtr& duid = query->getClientId();
if (!duid) {
// Can't do something useful: cross fingers.
return (true);
}
if (duid->getDuid().empty()) {
// A lot of code assumes this will never happen...
isc_throw(Unexpected, "empty DUID in ClientHandler::tryLock");
}
ClientPtr holder;
Pkt6Ptr next_query;
client_.reset(new Client(query, duid));
{
// Try to acquire the lock and return the holder when it failed.
lock_guard<mutex> lk(mutex_);
holder = lookup(duid);
if (!holder) {
locked_ = duid;
lock();
return (true);
}
// This query can be a duplicate so put the continuation.
if (cont) {
next_query = holder->next_query_;
holder->next_query_ = query;
holder->cont_ = cont;
}
}
if (cont) {
if (next_query) {
// Logging a warning as it is supposed to be a rare event
// with well behaving clients...
LOG_DEBUG(bad_packet6_logger, DBGLVL_PKT_HANDLING, DHCP6_PACKET_DROP_DUPLICATE)
.arg(next_query->toText())
.arg(this_thread::get_id())
.arg(holder->query_->toText())
.arg(holder->thread_);
stats::StatsMgr::instance().addValue("pkt6-receive-drop",
static_cast<int64_t>(1));
}
} else {
// Logging a warning as it is supposed to be a rare event
// with well behaving clients...
LOG_DEBUG(bad_packet6_logger, DBGLVL_PKT_HANDLING, DHCP6_PACKET_DROP_DUPLICATE)
.arg(query->toText())
.arg(this_thread::get_id())
.arg(holder->query_->toText())
.arg(holder->thread_);
stats::StatsMgr::instance().addValue("pkt6-receive-drop",
static_cast<int64_t>(1));
}
return (false);
}
void
ClientHandler::lock() {
// Sanity check.
if (!locked_) {
isc_throw(Unexpected, "nothing to lock in ClientHandler::lock");
}
add(client_);
}
void
ClientHandler::unLock() {
// Sanity check.
if (!locked_) {
isc_throw(Unexpected, "nothing to unlock in ClientHandler::unLock");
}
del(locked_);
locked_.reset();
if (!client_ || !client_->cont_) {
return;
}
// Try to process next query. As the caller holds the mutex of
// the handler class the continuation will be resumed after.
MultiThreadingMgr& mt_mgr = MultiThreadingMgr::instance();
if (mt_mgr.getMode()) {
if (!mt_mgr.getThreadPool().addFront(client_->cont_)) {
LOG_DEBUG(dhcp6_logger, DBG_DHCP6_BASIC, DHCP6_PACKET_QUEUE_FULL);
}
}
}
} // namespace dhcp
} // namespace isc
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