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/**
 * Valid format:
 *   "hostname;port" or "hostname;port;topic"
 */
bool is_valid_connection_str(
    char *connection_str,
    std::string& url,
    std::string& port)
{
    std::string str(connection_str);
    size_t n = std::count(str.begin(), str.end(), ';');
    if (n < 1 || n > 2)
    {
        // Connection string format is invalid
        return false;
    }
    
    std::istringstream iss(connection_str);
    std::getline(iss, url, ';');
    std::getline(iss, port, ';');
    
    if (url == "" || port == "")
    {
        // Connection string is invalid.
        // hostname or port is empty.
        return false;
    }
    return true;
}