Boolean Keys in Protobuf Maps Converted Incorrectly

[lishuoiscas]

Problem description

Hi all, we found an interesting bug. Given a map field which contained a key of type bool， when using a Node.js client to send the map field to a Python server, boolean keys in map fields are incorrectly deserialized in the response. Specifically, False keys are converted to True in the returned message.

Reproduction steps

The code snippet to help reproduce the issues is provided in Google drive.
You can reproduce the issue in either of the following two ways:

Option 1. Here is a simplified version of the code to reproduce the issue:
Proto file.

syntax = "proto3";

package map_hotpot;

option java_multiple_files = true;
option java_package = "org.grpctest.java.common.define";
option java_outer_classname = "MapProto";

message MapPot {
 map<bool, double> bool_double_value = 1;
 map<bool, int64> bool_int_value = 2;
 map<bool, bool> bool_bool_value = 3;
 map<bool, string> bool_string_value = 4;
}

service HotpotService {
 // UNARY
 rpc UnaryPot(MapPot) returns (MapPot);
}

Nodejs client request message:

const request = {
    bool_double_value: { true: 3.14 },
    bool_int_value: { false: 42 },
    bool_bool_value: { true: true },
    bool_string_value: { **false**: "hello" }
};

The response message as received by Python client

python server Received request: bool_double_value {
  key: true
  value: 3.14
}
bool_int_value {
  key: true
  value: 42
}
bool_bool_value {
  key: true
  value: true
}
bool_string_value {
  key: true
  value: "hello"
}

We can see that the second and fourth key are switched from "false" to "true", which is expected.

Option 2. For your convenience, we’ve provided the Docker image.
Load the Docker image: You can access it via this command ``docker pull lishuoiscas/grpc_app:0723
Prepare the code:
Create a folder named grpc-auto-test
Place the relevant code inside this folder
Run the Docker container:
Replace {your_path} with the absolute path to your local grpc-auto-test folder:
docker run -it --rm -v {your_path}/grpc-auto-test:/grpc-auto-test <image:tag>
Inside the container, reproduce the issue by running:

./ls_run.sh

Environment

• MacOs 15.3 and Windows 11
• Node version 22.17.1
  -Python 3.13

Additional context

Plausible reason: We confirmed the problem originated from Node.js server by analysing the response sent from Node.js server, as captured by tcpdump. This issue stemmed from the way Node.js convert map values to Javascript objects, where map keys must be a string. We have not found sufficient gRPC-node documentation to determine the exact cause behind this issue. However, it is very likely that the issue was caused by how the string form of map keys, as stored in Javascript objects, was converted to boolean type during serialization. In Javascript, the string “false”, when converted to a boolean value, will be boolean true (refer to the debuggping_process_1.png). If our assumption is true, then one solution to patch this bug would be to introduce a simple condition during string to boolean conversion as shown in the debuggping_process_2.png.
Please note that the suggested change was not based on gRPC-node code, it simply suggested a general idea to fix this issue.

Can you help fix it or double check it? Thank you.

[lishuoiscas]

Hi @dcodeIO Can you help fix or double check it? Sincerely, thank you for your help.