Mini Shell

"""
Support for Config Server Firewall (CSF)
========================================
:maintainer: Mostafa Hussein <mostafa.hussein91@gmail.com>
:maturity: new
:platform: Linux
"""

import re

import salt.utils.path
from salt.exceptions import CommandExecutionError, SaltInvocationError


def __virtual__():
    """
    Only load if csf exists on the system
    """
    if salt.utils.path.which("csf") is None:
        return (False, "The csf execution module cannot be loaded: csf unavailable.")
    else:
        return True


def _temp_exists(method, ip):
    """
    Checks if the ip exists as a temporary rule based
    on the method supplied, (tempallow, tempdeny).
    """
    _type = method.replace("temp", "").upper()
    cmd = (
        "csf -t | awk -v code=1 -v type={_type} -v ip={ip} '$1==type && $2==ip {{code=0}}"
        " END {{exit code}}'".format(_type=_type, ip=ip)
    )
    exists = __salt__["cmd.run_all"](cmd)
    return not bool(exists["retcode"])


def _exists_with_port(method, rule):
    path = f"/etc/csf/csf.{method}"
    return __salt__["file.contains"](path, rule)


def exists(
    method,
    ip,
    port=None,
    proto="tcp",
    direction="in",
    port_origin="d",
    ip_origin="d",
    ttl=None,
    comment="",
):
    """
    Returns true a rule for the ip already exists
    based on the method supplied. Returns false if
    not found.

    CLI Example:

    .. code-block:: bash

        salt '*' csf.exists allow 1.2.3.4
        salt '*' csf.exists tempdeny 1.2.3.4
    """
    if method.startswith("temp"):
        return _temp_exists(method, ip)
    if port:
        rule = _build_port_rule(
            ip, port, proto, direction, port_origin, ip_origin, comment
        )
        return _exists_with_port(method, rule)
    exists = __salt__["cmd.run_all"](f"egrep ^'{ip} +' /etc/csf/csf.{method}")
    return not bool(exists["retcode"])


def __csf_cmd(cmd):
    """
    Execute csf command
    """
    csf_cmd = "{} {}".format(salt.utils.path.which("csf"), cmd)
    out = __salt__["cmd.run_all"](csf_cmd)

    if out["retcode"] != 0:
        if not out["stderr"]:
            ret = out["stdout"]
        else:
            ret = out["stderr"]
        raise CommandExecutionError(f"csf failed: {ret}")
    else:
        ret = out["stdout"]
    return ret


def _status_csf():
    """
    Return True if csf is running otherwise return False
    """
    cmd = "test -e /etc/csf/csf.disable"
    out = __salt__["cmd.run_all"](cmd)
    return bool(out["retcode"])


def _get_opt(method):
    """
    Returns the cmd option based on a long form argument.
    """
    opts = {
        "allow": "-a",
        "deny": "-d",
        "unallow": "-ar",
        "undeny": "-dr",
        "tempallow": "-ta",
        "tempdeny": "-td",
        "temprm": "-tr",
    }
    return opts[method]


def _build_args(method, ip, comment):
    """
    Returns the cmd args for csf basic allow/deny commands.
    """
    opt = _get_opt(method)
    args = f"{opt} {ip}"
    if comment:
        args += f" {comment}"
    return args


def _access_rule(
    method,
    ip=None,
    port=None,
    proto="tcp",
    direction="in",
    port_origin="d",
    ip_origin="d",
    comment="",
):
    """
    Handles the cmd execution for allow and deny commands.
    """
    if _status_csf():
        if ip is None:
            return {"error": "You must supply an ip address or CIDR."}
        if port is None:
            args = _build_args(method, ip, comment)
            return __csf_cmd(args)
        else:
            if method not in ["allow", "deny"]:
                return {
                    "error": (
                        "Only allow and deny rules are allowed when specifying a port."
                    )
                }
            return _access_rule_with_port(
                method=method,
                ip=ip,
                port=port,
                proto=proto,
                direction=direction,
                port_origin=port_origin,
                ip_origin=ip_origin,
                comment=comment,
            )


def _build_port_rule(ip, port, proto, direction, port_origin, ip_origin, comment):
    kwargs = {
        "ip": ip,
        "port": port,
        "proto": proto,
        "direction": direction,
        "port_origin": port_origin,
        "ip_origin": ip_origin,
    }
    rule = "{proto}|{direction}|{port_origin}={port}|{ip_origin}={ip}".format(**kwargs)
    if comment:
        rule += f" #{comment}"

    return rule


def _remove_access_rule_with_port(
    method,
    ip,
    port,
    proto="tcp",
    direction="in",
    port_origin="d",
    ip_origin="d",
    ttl=None,
):

    rule = _build_port_rule(
        ip,
        port=port,
        proto=proto,
        direction=direction,
        port_origin=port_origin,
        ip_origin=ip_origin,
        comment="",
    )

    rule = rule.replace("|", "[|]")
    rule = rule.replace(".", "[.]")
    result = __salt__["file.replace"](
        f"/etc/csf/csf.{method}",
        pattern=f"^{rule}(( +)?\\#.*)?$\n",  # pylint: disable=W1401
        repl="",
    )

    return result


def _csf_to_list(option):
    """
    Extract comma-separated values from a csf.conf
    option and return a list.
    """
    result = []
    line = get_option(option)
    if line:
        csv = line.split("=")[1].replace(" ", "").replace('"', "")
        result = csv.split(",")
    return result


def split_option(option):
    return re.split(r"(?: +)?\=(?: +)?", option)


def get_option(option):
    pattern = rf'^{option}(\ +)?\=(\ +)?".*"$'  # pylint: disable=W1401
    grep = __salt__["file.grep"]("/etc/csf/csf.conf", pattern, "-E")
    if "stdout" in grep and grep["stdout"]:
        line = grep["stdout"]
        return line
    return None


def set_option(option, value):
    current_option = get_option(option)
    if not current_option:
        return {"error": "No such option exists in csf.conf"}
    result = __salt__["file.replace"](
        "/etc/csf/csf.conf",
        pattern=rf'^{option}(\ +)?\=(\ +)?".*"',  # pylint: disable=W1401
        repl=f'{option} = "{value}"',
    )

    return result


def get_skipped_nics(ipv6=False):
    if ipv6:
        option = "ETH6_DEVICE_SKIP"
    else:
        option = "ETH_DEVICE_SKIP"

    skipped_nics = _csf_to_list(option)
    return skipped_nics


def skip_nic(nic, ipv6=False):
    nics = get_skipped_nics(ipv6=ipv6)
    nics.append(nic)
    return skip_nics(nics, ipv6)


def skip_nics(nics, ipv6=False):
    if ipv6:
        ipv6 = "6"
    else:
        ipv6 = ""
    nics_csv = ",".join(map(str, nics))
    result = __salt__["file.replace"](
        "/etc/csf/csf.conf",
        # pylint: disable=anomalous-backslash-in-string
        pattern=rf'^ETH{ipv6}_DEVICE_SKIP(\ +)?\=(\ +)?".*"',
        # pylint: enable=anomalous-backslash-in-string
        repl=f'ETH{ipv6}_DEVICE_SKIP = "{nics_csv}"',
    )

    return result


def _access_rule_with_port(
    method,
    ip,
    port,
    proto="tcp",
    direction="in",
    port_origin="d",
    ip_origin="d",
    ttl=None,
    comment="",
):

    results = {}
    if direction == "both":
        directions = ["in", "out"]
    else:
        directions = [direction]
    for direction in directions:
        _exists = exists(
            method,
            ip,
            port=port,
            proto=proto,
            direction=direction,
            port_origin=port_origin,
            ip_origin=ip_origin,
            ttl=ttl,
            comment=comment,
        )
        if not _exists:
            rule = _build_port_rule(
                ip,
                port=port,
                proto=proto,
                direction=direction,
                port_origin=port_origin,
                ip_origin=ip_origin,
                comment=comment,
            )
            path = f"/etc/csf/csf.{method}"
            results[direction] = __salt__["file.append"](path, rule)
    return results


def _tmp_access_rule(
    method,
    ip=None,
    ttl=None,
    port=None,
    direction="in",
    port_origin="d",
    ip_origin="d",
    comment="",
):
    """
    Handles the cmd execution for tempdeny and tempallow commands.
    """
    if _status_csf():
        if ip is None:
            return {"error": "You must supply an ip address or CIDR."}
        if ttl is None:
            return {"error": "You must supply a ttl."}
        args = _build_tmp_access_args(method, ip, ttl, port, direction, comment)
        return __csf_cmd(args)


def _build_tmp_access_args(method, ip, ttl, port, direction, comment):
    """
    Builds the cmd args for temporary access/deny opts.
    """
    opt = _get_opt(method)
    args = f"{opt} {ip} {ttl}"
    if port:
        args += f" -p {port}"
    if direction:
        args += f" -d {direction}"
    if comment:
        args += f" #{comment}"
    return args


def running():
    """
    Check csf status

    CLI Example:

    .. code-block:: bash

        salt '*' csf.running
    """
    return _status_csf()


def disable():
    """
    Disable csf permanently

    CLI Example:

    .. code-block:: bash

        salt '*' csf.disable
    """
    if _status_csf():
        return __csf_cmd("-x")


def enable():
    """
    Activate csf if not running

    CLI Example:

    .. code-block:: bash

        salt '*' csf.enable
    """
    if not _status_csf():
        return __csf_cmd("-e")


def reload():
    """
    Restart csf

    CLI Example:

    .. code-block:: bash

        salt '*' csf.reload
    """
    return __csf_cmd("-r")


def tempallow(ip=None, ttl=None, port=None, direction=None, comment=""):
    """
    Add an rule to the temporary ip allow list.
    See :func:`_access_rule`.
    1- Add an IP:

    CLI Example:

    .. code-block:: bash

        salt '*' csf.tempallow 127.0.0.1 3600 port=22 direction='in' comment='# Temp dev ssh access'
    """
    return _tmp_access_rule("tempallow", ip, ttl, port, direction, comment)


def tempdeny(ip=None, ttl=None, port=None, direction=None, comment=""):
    """
    Add a rule to the temporary ip deny list.
    See :func:`_access_rule`.
    1- Add an IP:

    CLI Example:

    .. code-block:: bash

        salt '*' csf.tempdeny 127.0.0.1 300 port=22 direction='in' comment='# Brute force attempt'
    """
    return _tmp_access_rule("tempdeny", ip, ttl, port, direction, comment)


def allow(
    ip,
    port=None,
    proto="tcp",
    direction="in",
    port_origin="d",
    ip_origin="s",
    ttl=None,
    comment="",
):
    """
    Add an rule to csf allowed hosts
    See :func:`_access_rule`.
    1- Add an IP:

    CLI Example:

    .. code-block:: bash

        salt '*' csf.allow 127.0.0.1
        salt '*' csf.allow 127.0.0.1 comment="Allow localhost"
    """
    return _access_rule(
        "allow",
        ip,
        port=port,
        proto=proto,
        direction=direction,
        port_origin=port_origin,
        ip_origin=ip_origin,
        comment=comment,
    )


def deny(
    ip,
    port=None,
    proto="tcp",
    direction="in",
    port_origin="d",
    ip_origin="d",
    ttl=None,
    comment="",
):
    """
    Add an rule to csf denied hosts
    See :func:`_access_rule`.
    1- Deny an IP:

    CLI Example:

    .. code-block:: bash

        salt '*' csf.deny 127.0.0.1
        salt '*' csf.deny 127.0.0.1 comment="Too localhosty"
    """
    return _access_rule(
        "deny", ip, port, proto, direction, port_origin, ip_origin, comment
    )


def remove_temp_rule(ip):
    opt = _get_opt("temprm")
    args = f"{opt} {ip}"
    return __csf_cmd(args)


def unallow(ip):
    """
    Remove a rule from the csf denied hosts
    See :func:`_access_rule`.
    1- Deny an IP:

    CLI Example:

    .. code-block:: bash

        salt '*' csf.unallow 127.0.0.1
    """
    return _access_rule("unallow", ip)


def undeny(ip):
    """
    Remove a rule from the csf denied hosts
    See :func:`_access_rule`.
    1- Deny an IP:

    CLI Example:

    .. code-block:: bash

        salt '*' csf.undeny 127.0.0.1
    """
    return _access_rule("undeny", ip)


def remove_rule(
    method,
    ip,
    port=None,
    proto="tcp",
    direction="in",
    port_origin="d",
    ip_origin="s",
    ttl=None,
    comment="",
):

    if method.startswith("temp") or ttl:
        return remove_temp_rule(ip)

    if not port:
        if method == "allow":
            return unallow(ip)
        elif method == "deny":
            return undeny(ip)

    if port:
        return _remove_access_rule_with_port(
            method=method,
            ip=ip,
            port=port,
            proto=proto,
            direction=direction,
            port_origin=port_origin,
            ip_origin=ip_origin,
        )


def allow_ports(ports, proto="tcp", direction="in"):
    """
    Fully replace the incoming or outgoing ports
    line in the csf.conf file - e.g. TCP_IN, TCP_OUT,
    UDP_IN, UDP_OUT, etc.

    CLI Example:

    .. code-block:: bash

        salt '*' csf.allow_ports ports="[22,80,443,4505,4506]" proto='tcp' direction='in'
    """

    results = []
    ports = set(ports)
    ports = list(ports)
    proto = proto.upper()
    direction = direction.upper()
    _validate_direction_and_proto(direction, proto)
    ports_csv = ",".join(map(str, ports))
    directions = build_directions(direction)

    for direction in directions:
        result = __salt__["file.replace"](
            "/etc/csf/csf.conf",
            # pylint: disable=anomalous-backslash-in-string
            pattern=rf'^{proto}_{direction}(\ +)?\=(\ +)?".*"$',
            # pylint: enable=anomalous-backslash-in-string
            repl=f'{proto}_{direction} = "{ports_csv}"',
        )
        results.append(result)

    return results


def get_ports(proto="tcp", direction="in"):
    """
    Lists ports from csf.conf based on direction and protocol.
    e.g. - TCP_IN, TCP_OUT, UDP_IN, UDP_OUT, etc..

    CLI Example:

    .. code-block:: bash

        salt '*' csf.allow_port 22 proto='tcp' direction='in'
    """

    proto = proto.upper()
    direction = direction.upper()
    results = {}
    _validate_direction_and_proto(direction, proto)
    directions = build_directions(direction)
    for direction in directions:
        option = f"{proto}_{direction}"
        results[direction] = _csf_to_list(option)

    return results


def _validate_direction_and_proto(direction, proto):
    if direction.upper() not in ["IN", "OUT", "BOTH"]:
        raise SaltInvocationError("You must supply a direction of in, out, or both")
    if proto.upper() not in ["TCP", "UDP", "TCP6", "UDP6"]:
        raise SaltInvocationError(
            "You must supply tcp, udp, tcp6, or udp6 for the proto keyword"
        )
    return


def build_directions(direction):
    direction = direction.upper()
    if direction == "BOTH":
        directions = ["IN", "OUT"]
    else:
        directions = [direction]
    return directions


def allow_port(port, proto="tcp", direction="both"):
    """
    Like allow_ports, but it will append to the
    existing entry instead of replacing it.
    Takes a single port instead of a list of ports.

    CLI Example:

    .. code-block:: bash

        salt '*' csf.allow_port 22 proto='tcp' direction='in'
    """

    ports = get_ports(proto=proto, direction=direction)
    direction = direction.upper()
    _validate_direction_and_proto(direction, proto)
    directions = build_directions(direction)
    results = []
    for direction in directions:
        _ports = ports[direction]
        _ports.append(port)
        results += allow_ports(_ports, proto=proto, direction=direction)
    return results


def get_testing_status():
    testing = _csf_to_list("TESTING")[0]
    return testing


def _toggle_testing(val):
    if val == "on":
        val = "1"
    elif val == "off":
        val = "0"
    else:
        raise SaltInvocationError("Only valid arg is 'on' or 'off' here.")

    result = __salt__["file.replace"](
        "/etc/csf/csf.conf",
        pattern=r'^TESTING(\ +)?\=(\ +)?".*"',  # pylint: disable=W1401
        repl=f'TESTING = "{val}"',
    )
    return result


def enable_testing_mode():
    return _toggle_testing("on")


def disable_testing_mode():
    return _toggle_testing("off")