1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
|
/**
* Copyright (C) 2021-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/db/operation_context.h"
#include "mongo/db/service_context.h"
#include "mongo/rpc/message.h"
namespace mongo::rpc {
class RewriteStateChangeErrors {
public:
/**
* Enable/disable for an entire server.
* The default is determined by server parameter "rewriteStateChangeErrors".
*/
static bool getEnabled(ServiceContext* sc);
static void setEnabled(ServiceContext* sc, bool e);
/** Enable/disable only for a single operation. */
static bool getEnabled(OperationContext* opCtx);
static void setEnabled(OperationContext* opCtx, bool e);
/**
* State change codes are rewritten on the way out of a `mongos` server.
* Errors injected via `failCommand` manipulation are normally exempt from
* this. However, we provide an override option so they can be made subject
* to rewriting if that's really necessary.
*/
static void onActiveFailCommand(OperationContext* opCtx, const BSONObj& data);
/**
* Transforms an outgoing message to conditionally mask "state change" errors,
* which are errors that cause a client to change its connection to the host
* that sent it, such as marking it "Unknown". A shutdown error that's emitted
* by a proxy server (e.g. mongos) can be misinterpreted by a naive client to
* be indicative of the proxy server shutting down. So this simple rewrite
* scheme attempts to mask those errors on the way out.
*
* Return a disengaged optional if no rewrite is needed.
* Otherwise, returns a copy of doc with the errors rewritten.
*
* Error-bearing subobjects are places in the document where a `code` element
* can indicate an error status. When rewriting, any error-bearing subobjects
* are examined for a `code` element.
*
* In an error document (with "ok" mapped to 0.0), only the root element is
* error-bearing. In a success document (where "ok" is mapped to 1.0), the
* `writeConcernError` subobject and all the subobjects in the `writeErrors`
* BSON array are error-bearing subobjects.
*
* Rewriting occurs only if all of these conditions are met:
*
* - This feature wasn't deselected with a `setEnabled` call, either on the
* `opCtx` or for more widely for its associated ServiceContext.
* This will happen with failpoint-induced errors or with "hello" commands,
* both of which are exempt from state change error rewriting.
*
* - doc contains no error nodes that need rewriting.
* - NotPrimaryError codes always need rewriting.
* - ShutdownError codes need rewriting unless this server is
* shutting down.
*
* Any rewritten `code` is replaced by `HostUnreachable`, and associated
* `codeName` replaced to be consistent with the new code. Additionally, the
* `errmsg` in the subobject has all occurrences of the key phrases "not
* master" and "node is recovering" replaced with "(NOT_PRIMARY)" and
* "(NODE_IS_RECOVERING)" respectively so that client state changes based on
* the presence of these legacy strings are suppressed.
*/
static boost::optional<BSONObj> rewrite(BSONObj doc, OperationContext* opCtx);
};
} // namespace mongo::rpc
|
