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fix: crash when parsing invalid json config #52

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Merged
greghuels merged 2 commits into from
Jan 27, 2026
Merged

fix: crash when parsing invalid json config #52

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330ff1a
fix: crash when parsing invalid json config
greghuels Jan 27, 2026
1afa0f3
chore: bump to version 2.0.3
greghuels Jan 27, 2026
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4 changes: 4 additions & 0 deletions CHANGELOG.md
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Expand Up @@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0

**Note**: Semantic Versioning applies to source-level compatibility only. No guarantees are made regarding Application Binary Interface (ABI) stability. When upgrading versions, always recompile your application against the new SDK version. Avoid mixing object files or libraries compiled against different SDK versions.

## [2.0.3] - 2026-01-27

- fix crash in `parseConfigResponse` when receiving empty, null, or non-object JSON input (#51)

## [2.0.2] - 2026-01-14

- fix time_utils fmodules build
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2 changes: 1 addition & 1 deletion Makefile
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Expand Up @@ -173,7 +173,7 @@ help:
@echo " test-eval-performance - Run flag evaluation performance tests (min/max/avg μs)"
@echo " examples - Build all examples"
@echo " run-bandits - Build and run the bandits example"
@echo " run-flag-assignments - Build and run the flag_assignments example"
@echo " run-flags - Build and run the flag_assignments example"
@echo " run-assignment-details - Build and run the assignment_details example"
@echo " run-manual-sync - Build and run the manual_sync example"
@echo " format - Format all C++ source files with clang-format"
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7 changes: 7 additions & 0 deletions src/config_response.cpp
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Expand Up @@ -627,6 +627,13 @@ ParseResult<ConfigResponse> parseConfigResponse(const nlohmann::json& j) {
ParseResult<ConfigResponse> result;
ConfigResponse cr;

// Validate that input is a JSON object
if (!j.is_object()) {
result.errors.push_back("ConfigResponse: Expected a JSON object, got " +
std::string(j.type_name()));
Comment on lines +632 to +633
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@leoromanovsky leoromanovsky Jan 27, 2026

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consider another log line that prints out the received configuration to give them a totally self service way to iterate; alternatively does this error give them a strong enough signal that they could catch and print it themselves?

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@greghuels greghuels Jan 27, 2026

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The current error message includes the JSON type name (e.g., "Expected a JSON object, got null" or "got array"), which should give a good signal about what happened. Since parseConfigResponse returns a ParseResult with the error in result.errors, consuming apps can catch and log the full input themselves. So we should be good 👍

return result;
}

// Parse flags - required field
if (!j.contains("flags")) {
result.errors.push_back("ConfigResponse: Missing required field: flags");
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2 changes: 1 addition & 1 deletion src/version.hpp
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Expand Up @@ -6,7 +6,7 @@

#define EPPOCLIENT_VERSION_MAJOR 2
#define EPPOCLIENT_VERSION_MINOR 0
#define EPPOCLIENT_VERSION_PATCH 2
#define EPPOCLIENT_VERSION_PATCH 3
#define EPPOCLIENT_VERSION \
(EPPO_STRINGIFY(EPPOCLIENT_VERSION_MAJOR) "." EPPO_STRINGIFY( \
EPPOCLIENT_VERSION_MINOR) "." EPPO_STRINGIFY(EPPOCLIENT_VERSION_PATCH))
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90 changes: 90 additions & 0 deletions test/test_config_response_json.cpp
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Expand Up @@ -172,6 +172,96 @@ TEST_CASE("ConfigResponse deserialization - empty config", "[config_response][js
REQUIRE(result->flags.empty());
}

TEST_CASE("ConfigResponse deserialization - empty string input", "[config_response][json]") {
std::string emptyString = "";

auto result = parseConfigResponse(emptyString);
REQUIRE_FALSE(result.hasValue());
REQUIRE(result.errors.size() == 1);
REQUIRE(result.errors[0].find("JSON parse error") != std::string::npos);
}

TEST_CASE("ConfigResponse deserialization - null JSON input", "[config_response][json]") {
json j = nullptr;

auto result = parseConfigResponse(j);
REQUIRE_FALSE(result.hasValue());
REQUIRE(result.errors.size() == 1);
REQUIRE(result.errors[0].find("Expected a JSON object") != std::string::npos);
}

TEST_CASE("ConfigResponse deserialization - null JSON string input", "[config_response][json]") {
std::string nullString = "null";

auto result = parseConfigResponse(nullString);
REQUIRE_FALSE(result.hasValue());
REQUIRE(result.errors.size() == 1);
REQUIRE(result.errors[0].find("Expected a JSON object") != std::string::npos);
}

TEST_CASE("ConfigResponse deserialization - array JSON input", "[config_response][json]") {
json j = json::array();

auto result = parseConfigResponse(j);
REQUIRE_FALSE(result.hasValue());
REQUIRE(result.errors.size() == 1);
REQUIRE(result.errors[0].find("Expected a JSON object") != std::string::npos);
}

TEST_CASE("ConfigResponse deserialization - array JSON string input", "[config_response][json]") {
std::string arrayString = "[]";

auto result = parseConfigResponse(arrayString);
REQUIRE_FALSE(result.hasValue());
REQUIRE(result.errors.size() == 1);
REQUIRE(result.errors[0].find("Expected a JSON object") != std::string::npos);
}

TEST_CASE("ConfigResponse deserialization - number JSON input", "[config_response][json]") {
json j = 123;

auto result = parseConfigResponse(j);
REQUIRE_FALSE(result.hasValue());
REQUIRE(result.errors.size() == 1);
REQUIRE(result.errors[0].find("Expected a JSON object") != std::string::npos);
}

TEST_CASE("ConfigResponse deserialization - string JSON input", "[config_response][json]") {
json j = "not an object";

auto result = parseConfigResponse(j);
REQUIRE_FALSE(result.hasValue());
REQUIRE(result.errors.size() == 1);
REQUIRE(result.errors[0].find("Expected a JSON object") != std::string::npos);
}

TEST_CASE("ConfigResponse deserialization - boolean JSON input", "[config_response][json]") {
json j = true;

auto result = parseConfigResponse(j);
REQUIRE_FALSE(result.hasValue());
REQUIRE(result.errors.size() == 1);
REQUIRE(result.errors[0].find("Expected a JSON object") != std::string::npos);
}

TEST_CASE("ConfigResponse deserialization - malformed JSON string", "[config_response][json]") {
std::string malformed = "{invalid json";

auto result = parseConfigResponse(malformed);
REQUIRE_FALSE(result.hasValue());
REQUIRE(result.errors.size() == 1);
REQUIRE(result.errors[0].find("JSON parse error") != std::string::npos);
}

TEST_CASE("ConfigResponse deserialization - truncated JSON string", "[config_response][json]") {
std::string truncated = R"({"flags": {"test": {"key": "t)";

auto result = parseConfigResponse(truncated);
REQUIRE_FALSE(result.hasValue());
REQUIRE(result.errors.size() == 1);
REQUIRE(result.errors[0].find("JSON parse error") != std::string::npos);
}

TEST_CASE("ConfigResponse deserialization - single simple flag", "[config_response][json]") {
json j = R"({
"flags": {
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