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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <boost/optional.hpp>
#include "mongo/bson/bsonobjbuilder.h"
#include "mongo/stdx/mutex.h"
#include "mongo/util/assert_util.h"
namespace mongo {
/**
* The 'WireVersion' captures all "protocol events" the write protocol went through. A
* protocol event is a change in the syntax of messages on the wire or the semantics of
* existing messages. We may also add "logical" entries for releases, although that's not
* mandatory.
*
* We use the wire version to determine if two agents (a driver, a mongos, or a mongod) can
* interact. Each agent carries two versions, a 'max' and a 'min' one. If the two agents
* are on the same 'max' number, they stricly speak the same wire protocol and it is safe
* to allow them to communicate. If two agents' ranges do not intersect, they should not be
* allowed to communicate.
*
* If two agents have at least one version in common they can communicate, but one of the
* sides has to be ready to compensate for not being on its partner version.
*/
enum WireVersion {
// Everything before we started tracking.
RELEASE_2_4_AND_BEFORE = 0,
// The aggregation command may now be requested to return cursors.
AGG_RETURNS_CURSORS = 1,
// insert, update, and delete batch command
BATCH_COMMANDS = 2,
// support SCRAM-SHA1, listIndexes, listCollections, new explain
RELEASE_2_7_7 = 3,
// Support find and getMore commands, as well as OP_COMMAND in mongod (but not mongos).
FIND_COMMAND = 4,
// Supports all write commands take a write concern.
COMMANDS_ACCEPT_WRITE_CONCERN = 5,
// Supports the new OP_MSG wireprotocol (3.6+).
SUPPORTS_OP_MSG = 6,
// Supports replica set transactions (4.0+).
REPLICA_SET_TRANSACTIONS = 7,
// Supports sharded transactions (4.2+).
SHARDED_TRANSACTIONS = 8,
// Supports resumable initial sync (4.4+).
RESUMABLE_INITIAL_SYNC = 9,
// Supports features available from 4.7 and onwards.
WIRE_VERSION_47 = 10,
// Supports features available from 4.8 and onwards.
WIRE_VERSION_48 = 11,
// Supports features available from 4.9 and onwards.
WIRE_VERSION_49 = 12,
// Supports features available from 5.0 and onwards.
WIRE_VERSION_50 = 13,
// Set this to the highest value in this enum - it will be the default maxWireVersion for
// the WireSpec values.
LATEST_WIRE_VERSION = WIRE_VERSION_50,
// Set this to LATEST_WIRE_VERSION - 1.
LAST_CONT_WIRE_VERSION = LATEST_WIRE_VERSION - 1,
// Set this to the wire version of the previous LTS version. We expect to update this after
// each LTS release.
LAST_LTS_WIRE_VERSION = RESUMABLE_INITIAL_SYNC,
};
/**
* Struct to pass around information about wire version.
*/
struct WireVersionInfo {
int minWireVersion;
int maxWireVersion;
static void appendToBSON(const WireVersionInfo& versionInfo, BSONObjBuilder* bob) {
bob->append("minWireVersion", versionInfo.minWireVersion);
bob->append("maxWireVersion", versionInfo.maxWireVersion);
}
};
class WireSpec {
public:
struct Specification {
// incomingExternalClient.minWireVersion - Minimum version that the server accepts on
// incoming requests from external clients. We should bump this whenever we don't want to
// allow incoming connections from clients that are too old.
// incomingExternalClient.maxWireVersion - Latest version that the server accepts on
// incoming requests from external clients. This should always be at the latest entry in
// WireVersion.
WireVersionInfo incomingExternalClient = {RELEASE_2_4_AND_BEFORE, LATEST_WIRE_VERSION};
// incomingInternalClient.minWireVersion - Minimum version that the server accepts on
// incoming requests from internal clients. This should be
// incomingInternalClient.maxWireVersion - 1, when the featureCompatibilityVersion is equal
// to the downgrade version, and incomingInternalClient.maxWireVersion otherwise. However,
// in 3.6, this needs to be RELEASE_2_4_AND_BEFORE when the featureCompatibilityVersion is
// equal to the downgrade version due to a bug in 3.4, where if the receiving node says it
// supports wire version range [COMMANDS_ACCEPT_WRITE_CONCERN, SUPPORTS_OP_MSG] and it is a
// mongod, the initiating node will think it only supports OP_QUERY.
// incomingInternalClient.maxWireVersion - Latest version that the server accepts on
// incoming requests. This should always be at the latest entry in WireVersion.
WireVersionInfo incomingInternalClient = {RELEASE_2_4_AND_BEFORE, LATEST_WIRE_VERSION};
// outgoing.minWireVersion - Minimum version allowed on remote nodes when the server sends
// requests. This should be outgoing.maxWireVersion - 1, when the
// featureCompatibilityVersion is equal to the downgrade version, and
// outgoing.maxWireVersion otherwise. However, in 3.6, this needs to be
// RELEASE_2_4_AND_BEFORE when the featureCompatibilityVersion is equal to the downgrade
// version due to a bug in 3.4, where if the receiving node says it supports wire version
// range [COMMANDS_ACCEPT_WRITE_CONCERN, SUPPORTS_OP_MSG] and it is a mongod, the initiating
// node will think it only supports OP_QUERY.
// outgoing.maxWireVersion - Latest version allowed on remote nodes when the server sends
// requests.
WireVersionInfo outgoing = {RELEASE_2_4_AND_BEFORE, LATEST_WIRE_VERSION};
// Set to true if the client is internal to the cluster---this is a mongod or mongos
// connecting to another mongod.
bool isInternalClient = false;
static void appendToBSON(const Specification& spec, BSONObjBuilder* bob) {
auto appendWireVersion = [bob](std::string tag,
const WireVersionInfo& wireVersionInfo) {
BSONObjBuilder builder = bob->subobjStart(tag);
WireVersionInfo::appendToBSON(wireVersionInfo, &builder);
};
appendWireVersion("incomingExternalClient", spec.incomingExternalClient);
appendWireVersion("incomingInternalClient", spec.incomingInternalClient);
appendWireVersion("outgoing", spec.outgoing);
bob->append("isInternalClient", spec.isInternalClient);
}
};
public:
static WireSpec& instance();
/**
* Appends the min and max versions in 'wireVersionInfo' to 'builder' in the format expected for
* reporting information about the internal client.
*
* Intended for use as part of performing the isMaster handshake with a remote node. When an
* internal clients make a connection to another node in the cluster, it includes internal
* client information as a parameter to the isMaster command. This parameter has the following
* format:
*
* internalClient: {
* minWireVersion: <int>,
* maxWireVersion: <int>
* }
*
* This information can be used to ensure correctness during upgrade in mixed version clusters.
*/
static void appendInternalClientWireVersion(WireVersionInfo wireVersionInfo,
BSONObjBuilder* builder);
void initialize(Specification spec);
void reset(Specification spec);
// Calling `get()` on uninitialized instances of `WireSpec` is prohibited.
std::shared_ptr<const Specification> get() const;
bool isInitialized() const {
return _spec ? true : false;
}
private:
// Ensures concurrent accesses to `get()` and `reset()` are thread-safe.
mutable Mutex _mutex = MONGO_MAKE_LATCH("WireSpec::_mutex");
std::shared_ptr<const Specification> _spec;
};
} // namespace mongo
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