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
104
105
106
107
108
109
110
111
112
113
114
115
116
|
/**
* 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.
*/
#include "mongo/platform/basic.h"
#include "mongo/rpc/legacy_request_builder.h"
#include <memory>
#include <tuple>
#include <utility>
#include "mongo/client/read_preference.h"
#include "mongo/db/dbmessage.h"
#include "mongo/db/namespace_string.h"
#include "mongo/rpc/message.h"
#include "mongo/rpc/metadata.h"
#include "mongo/util/assert_util.h"
namespace mongo {
namespace rpc {
namespace {
void mergeInDocumentSequences(const OpMsgRequest& request, BSONObjBuilder* body) {
for (auto&& seq : request.sequences) {
invariant(seq.name.find('.') == std::string::npos); // Only support top-level for now.
dassert(!body->asTempObj().hasField(seq.name));
body->append(seq.name, seq.objs);
}
}
/**
* Given a command request, attempts to construct a legacy command
* object and query flags bitfield augmented with the given metadata.
*/
BSONObj downconvertRequestBody(const OpMsgRequest& request, int* queryOptions) {
*queryOptions = 0;
if (auto readPref = request.body["$readPreference"]) {
auto parsed = ReadPreferenceSetting::fromInnerBSON(readPref);
if (parsed.isOK() && parsed.getValue().canRunOnSecondary()) {
*queryOptions |= QueryOption_SlaveOk;
}
BSONObjBuilder outer;
{
BSONObjBuilder inner(outer.subobjStart("$query"));
for (auto field : request.body) {
const auto name = field.fieldNameStringData();
if (name == "$readPreference" || name == "$db") {
// skip field.
} else {
inner.append(field);
}
}
mergeInDocumentSequences(request, &inner);
}
outer.append(readPref);
return outer.obj();
} else {
BSONObjBuilder body(request.body.removeField("$db"));
mergeInDocumentSequences(request, &body);
return body.obj();
}
}
} // namespace
Message legacyRequestFromOpMsgRequest(const OpMsgRequest& request) {
BufBuilder builder;
builder.skip(mongo::MsgData::MsgDataHeaderSize);
const auto cmdNS = NamespaceString(request.getDatabase(), "").getCommandNS().toString();
int queryOptions;
const auto downconvertedBody = downconvertRequestBody(request, &queryOptions);
builder.appendNum(queryOptions);
builder.appendStr(cmdNS);
builder.appendNum(0); // nToSkip
builder.appendNum(1); // nToReturn
downconvertedBody.appendSelfToBufBuilder(builder);
MsgData::View msg = builder.buf();
msg.setLen(builder.len());
msg.setOperation(dbQuery);
return Message(builder.release());
}
} // namespace rpc
} // namespace mongo
|
