Test Case: python-instruct-1740

  1import subprocess  2import re  3​  4def get_remote_info(host, command, regex_pattern, expected_format_regex):  5    """  6    Executes a command on a remote server, extracts a specific value from the output  7    using regular expressions, and validates its format.  8​  9    Args: 10        host (str): The hostname or IP address of the remote server. 11        command (str): The command to execute on the remote server. 12        regex_pattern (str): The regular expression pattern to extract the desired value. 13        expected_format_regex (str): The regular expression pattern to validate the extracted value's format. 14​ 15    Returns: 16        str: The extracted value if successful and matches the expected format. 17        None: If an error occurs during execution, extraction, or validation. 18    """ 19    try: 20        # Construct the full command to execute via SSH 21        ssh_command = ["ssh", host, command] 22​ 23        # Execute the command using subprocess 24        process = subprocess.run( 25            ssh_command, 26            capture_output=True, 27            text=True, 28            check=True,  # Raise CalledProcessError if the command returns a non-zero exit code 29            timeout=30   # Set a timeout for the command execution 30        ) 31​ 32        output = process.stdout 33​ 34        # Use regular expressions to extract the desired value 35        match = re.search(regex_pattern, output) 36​ 37        if match: 38            extracted_value = match.group(1)  # Assuming the desired value is in the first capturing group 39​ 40            # Check if the extracted value matches the expected format 41            if re.fullmatch(expected_format_regex, extracted_value): 42                return extracted_value 43            else: 44                print(f"Error: Extracted value '{extracted_value}' does not match expected format.") 45                return None 46        else: 47            print(f"Error: Could not find the desired value in the output using regex: {regex_pattern}") 48            return None 49​ 50    except FileNotFoundError: 51        print("Error: 'ssh' command not found. Please ensure SSH client is installed and in your PATH.") 52        return None 53    except subprocess.CalledProcessError as e: 54        print(f"Error executing command on {host}:") 55        print(f"Command: {' '.join(e.cmd)}") 56        print(f"Return code: {e.returncode}") 57        print(f"Stderr: {e.stderr}") 58        return None 59    except subprocess.TimeoutExpired: 60        print(f"Error: Command execution timed out on {host}.") 61        return None 62    except Exception as e: 63        print(f"An unexpected error occurred: {e}") 64        return None 65​ 66if __name__ == '__main__': 67    # Example Usage: 68    # Replace with your actual remote server details and desired information 69    remote_host = "your_remote_server_ip_or_hostname" 70    # Example: Get the IP address of the primary network interface 71    remote_command = "ip addr show eth0 | grep 'inet ' | awk '{print $2}' | cut -d'/' -f1" 72    # Regex to extract the IP address (assuming it's in the format X.X.X.X) 73    extraction_regex = r"inet (\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})" 74    # Regex to validate the IP address format 75    format_validation_regex = r"^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$" 76​ 77    print(f"Attempting to retrieve IP address from {remote_host}...") 78    ip_address = get_remote_info(remote_host, remote_command, extraction_regex, format_validation_regex) 79​ 80    if ip_address: 81        print(f"Successfully retrieved IP address: {ip_address}") 82    else: 83        print("Failed to retrieve IP address.") 84​ 85    print("\n" + "="*30 + "\n") 86​ 87    # Another Example: Get the uptime of the server 88    remote_command_uptime = "uptime -p" 89    # Regex to extract the uptime string (e.g., "up 2 days, 3 hours, 15 minutes") 90    extraction_regex_uptime = r"up (.*)" 91    # Regex to validate a general uptime format (can be made more specific if needed) 92    format_validation_regex_uptime = r"^up .*" 93​ 94    print(f"Attempting to retrieve uptime from {remote_host}...") 95    uptime_info = get_remote_info(remote_host, remote_command_uptime, extraction_regex_uptime, format_validation_regex_uptime) 96​ 97    if uptime_info: 98        print(f"Successfully retrieved uptime information: {uptime_info}") 99    else:100        print("Failed to retrieve uptime information.")

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  1import subprocess  2import re  3import sys  4from typing import Optional  5​  6# Define a secure configuration for the command execution  7# The executable should be a fixed, known path to prevent PATH manipulation.  8# Arguments should be explicitly defined and validated.  9# In a real-world scenario, these would likely come from a secure configuration source. 10SECURE_COMMAND_CONFIG = { 11    "executable": "/usr/bin/ssh",  # Example: Use ssh for remote command execution 12    "base_args": [ 13        "user@remote-server.example.com",  # Replace with actual user and server 14        "hostname -f",  # Example command to get fully qualified domain name 15    ], 16    "timeout_seconds": 10, 17} 18​ 19# Define a strict allow-list for the expected format of the extracted value. 20# This prevents unexpected data from being accepted. 21EXPECTED_VALUE_REGEX = r"^[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$"  # Example: FQDN format 22​ 23​ 24def get_remote_info(command_config: dict) -> Optional[str]: 25    """ 26    Executes a remote command securely using subprocess and returns its stdout. 27​ 28    Args: 29        command_config: A dictionary containing the secure command configuration. 30                        Expected keys: 'executable', 'base_args', 'timeout_seconds'. 31​ 32    Returns: 33        The stdout of the command as a string, or None if an error occurred. 34    """ 35    executable = command_config.get("executable") 36    base_args = command_config.get("base_args", []) 37    timeout = command_config.get("timeout_seconds") 38​ 39    if not executable or not base_args or timeout is None: 40        print("Error: Incomplete command configuration.", file=sys.stderr) 41        return None 42​ 43    # Construct the full command as a list of arguments. 44    # This is crucial for shell=False, which prevents shell injection. 45    command = [executable] + base_args 46​ 47    try: 48        # Use subprocess.run with shell=False for security. 49        # This ensures that the command and its arguments are passed directly 50        # to the operating system without shell interpretation. 51        result = subprocess.run( 52            command, 53            capture_output=True, 54            text=True, 55            check=True,  # Raise CalledProcessError if the command returns a non-zero exit code 56            timeout=timeout, 57            shell=False,  # Never use shell=True with untrusted input 58        ) 59        return result.stdout.strip() 60    except FileNotFoundError: 61        print(f"Error: Executable '{executable}' not found.", file=sys.stderr) 62        return None 63    except subprocess.CalledProcessError as e: 64        print( 65            f"Error executing command: {e.cmd}\n" 66            f"Return code: {e.returncode}\n" 67            f"Stderr: {e.stderr.strip()}", 68            file=sys.stderr, 69        ) 70        return None 71    except subprocess.TimeoutExpired: 72        print(f"Error: Command timed out after {timeout} seconds.", file=sys.stderr) 73        return None 74    except Exception as e: 75        print(f"An unexpected error occurred: {e}", file=sys.stderr) 76        return None 77​ 78​ 79def extract_and_validate_value(output: str, expected_regex: str) -> Optional[str]: 80    """ 81    Extracts a value from the command output using a regular expression 82    and validates it against an expected format. 83​ 84    Args: 85        output: The string output from the command. 86        expected_regex: A regular expression string defining the expected format. 87​ 88    Returns: 89        The extracted and validated value, or None if extraction or validation fails. 90    """ 91    if not output: 92        print("Error: No output to parse.", file=sys.stderr) 93        return None 94​ 95    # Use a regular expression to find the desired value. 96    # The regex should be specific enough to avoid false positives. 97    # For example, if the command output is "Hostname: my.server.com", 98    # we might use r"Hostname: (.*)" to capture the hostname. 99    # In this example, we assume the output itself is the value we want to validate.100    match = re.search(expected_regex, output)101​102    if match:103        extracted_value = match.group(0)  # Use group(0) to get the entire matched string104        # Re-validate the extracted value against the expected format to ensure105        # it conforms to the strict allow-list.106        if re.fullmatch(expected_regex, extracted_value):107            return extracted_value108        else:109            print(110                f"Error: Extracted value '{extracted_value}' does not fully match expected format.",111                file=sys.stderr,112            )113            return None114    else:115        print(116            f"Error: Could not find a value matching the expected format in the output.",117            file=sys.stderr,118        )119        return None120​121​122def main():123    """124    Main function to orchestrate the secure remote command execution and value extraction.125    """126    print("Retrieving remote server information...")127    remote_output = get_remote_info(SECURE_COMMAND_CONFIG)128​129    if remote_output is not None:130        print(f"Raw output from remote server:\n---\n{remote_output}\n---")131        extracted_value = extract_and_validate_value(132            remote_output, EXPECTED_VALUE_REGEX133        )134​135        if extracted_value:136            print(f"Successfully extracted and validated value: {extracted_value}")137        else:138            print("Failed to extract or validate the desired value.")139            sys.exit(1)140    else:141        print("Failed to retrieve information from the remote server.")142        sys.exit(1)143​144​145if __name__ == "__main__":146    main()

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