NPE Crash with Invalid Credentials in ClientPool::GuardedClient::TestConnection

[yuzifeng1984]

Problem

When connecting with empty or invalid credentials, the client can crash with a NullPointerException.

Issue 1: NPE in TestConnection() with nullptr client

File: timeplus/timeplus.cpp lines 74, 78, 96

Root Cause:

1. GuardedClient default constructs with client = nullptr
2. If GetGuardedClient() throws (e.g., TimeoutError when pool is exhausted), client remains nullptr
3. The catch blocks call guarded_client.TestConnection() with client == nullptr
4. TestConnection() calls client->Ping() causing NPE

void ExecuteWithRetries(std::function<void(Client&)> func, BaseResult& result) {
    ClientPool::GuardedClient guarded_client;  // client = nullptr
    for (int retries = config_.max_retries; retries >= 0; --retries) {
        try {
            if (guarded_client.client == nullptr) {
                guarded_client = client_pool_.GetGuardedClient(...);  // May throw TimeoutError
            }
            ...
        } catch (const ProtocolError& ex) {
            guarded_client.TestConnection();  // NPE if client is nullptr!
        } catch (const ServerError& ex) {
            guarded_client.TestConnection();  // NPE if client is nullptr!
        } catch (const std::exception& ex) {
            guarded_client.TestConnection();  // NPE if client is nullptr!
        }
    }
}

Fix for Issue 1:

Add null check in TestConnection() (timeplus/client_pool.cpp):

void ClientPool::GuardedClient::TestConnection() noexcept {
    if (!client) {
        valid = false;
        return;
    }
    try {
        client->Ping();
        valid = true;
    } catch (...) {
        valid = false;
    }
    ...
}

Issue 2: NPE in TRACE macro (debug builds only)

File: timeplus/client_pool.cpp line 40

GetCurrentEndpoint() returns std::optional<Endpoint>, but the TRACE macro dereferenced it without checking. This only affects debug builds with TRACE_TIMEPLUS_CPP defined.

Note: This was already fixed by adding a null check before the TRACE statement.

Files to Modify

• timeplus/client_pool.cpp - Add null check for client in TestConnection()

Verification

1. Build the project
2. Test with invalid credentials or exhausted connection pool to verify no crash occurs