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Filename : functions.py
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# -*- coding: utf-8 -*-
#
# Copyright (C) 2007,2008,2011,2012 Red Hat, Inc.
#
# Authors:
# Thomas Woerner <twoerner@redhat.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

__all__ = [ "PY2", "getPortID", "getPortRange", "portStr", "getServiceName",
            "checkIP", "checkIP6", "checkIPnMask", "checkIP6nMask",
            "checkProtocol", "checkInterface", "checkUINT32",
            "firewalld_is_active", "tempFile", "readfile", "writefile",
            "enable_ip_forwarding", "get_nf_conntrack_helper_setting",
            "set_nf_conntrack_helper_setting", "check_port", "check_address",
            "check_single_address", "check_mac", "uniqify", "ppid_of_pid",
            "max_zone_name_len", "checkUser", "checkUid", "checkCommand",
            "checkContext", "joinArgs", "splitArgs",
            "b2u", "u2b", "u2b_if_py2" ]

import socket
import os
import os.path
import shlex
import pipes
import string
import sys
import tempfile
from firewall.core.logger import log
from firewall.config import FIREWALLD_TEMPDIR, FIREWALLD_PIDFILE

PY2 = sys.version < '3'

def getPortID(port):
    """ Check and Get port id from port string or port id using socket.getservbyname

    @param port port string or port id
    @return Port id if valid, -1 if port can not be found and -2 if port is too big
    """

    if isinstance(port, int):
        _id = port
    else:
        if port:
            port = port.strip()
        try:
            _id = int(port)
        except ValueError:
            try:
                _id = socket.getservbyname(port)
            except socket.error:
                return -1
    if _id > 65535:
        return -2
    return _id

def getPortRange(ports):
    """ Get port range for port range string or single port id

    @param ports an integer or port string or port range string
    @return Array containing start and end port id for a valid range or -1 if port can not be found and -2 if port is too big for integer input or -1 for invalid ranges or None if the range is ambiguous.
    """

    # "<port-id>" case
    if isinstance(ports, int) or ports.isdigit():
        id1 = getPortID(ports)
        if id1 >= 0:
            return (id1,)
        return id1

    splits = ports.split("-")

    # "<port-id>-<port-id>" case
    if len(splits) == 2 and splits[0].isdigit() and splits[1].isdigit():
        id1 = getPortID(splits[0])
        id2 = getPortID(splits[1])
        if id1 >= 0 and id2 >= 0:
            if id1 < id2:
                return (id1, id2)
            elif id1 > id2:
                return (id2, id1)
            else: # ids are the same
                return (id1,)

    # everything else "<port-str>[-<port-str>]"
    matched = [ ]
    for i in range(len(splits), 0, -1):
        id1 = getPortID("-".join(splits[:i]))
        port2 = "-".join(splits[i:])
        if len(port2) > 0:
            id2 = getPortID(port2)
            if id1 >= 0 and id2 >= 0:
                if id1 < id2:
                    matched.append((id1, id2))
                elif id1 > id2:
                    matched.append((id2, id1))
                else:
                    matched.append((id1, ))
        else:
            if id1 >= 0:
                matched.append((id1,))
                if i == len(splits):
                    # full match, stop here
                    break
    if len(matched) < 1:
        return -1
    elif len(matched) > 1:
        return None
    return matched[0]

def portStr(port, delimiter=":"):
    """ Create port and port range string

    @param port port or port range int or [int, int]
    @param delimiter of the output string for port ranges, default ':'
    @return Port or port range string, empty string if port isn't specified, None if port or port range is not valid
    """
    if port == "":
        return ""

    _range = getPortRange(port)
    if isinstance(_range, int) and _range < 0:
        return None
    elif len(_range) == 1:
        return "%s" % _range
    else:
        return "%s%s%s" % (_range[0], delimiter, _range[1])

def portInPortRange(port, range):
    _port = getPortID(port)
    _range = getPortRange(range)

    if len(_range) == 1:
        return _port == getPortID(_range[0])
    if len(_range) == 2 and \
       _port >= getPortID(_range[0]) and _port <= getPortID(_range[1]):
        return True

    return False

def getServiceName(port, proto):
    """ Check and Get service name from port and proto string combination using socket.getservbyport

    @param port string or id
    @param protocol string
    @return Service name if port and protocol are valid, else None
    """

    try:
        name = socket.getservbyport(int(port), proto)
    except socket.error:
        return None
    return name

def checkIP(ip):
    """ Check IPv4 address.
    
    @param ip address string
    @return True if address is valid, else False
    """

    try:
        socket.inet_pton(socket.AF_INET, ip)
    except socket.error:
        return False
    return True

def normalizeIP6(ip):
    """ Normalize the IPv6 address

    This is mostly about converting URL-like IPv6 address to normal ones.
    e.g. [1234::4321] --> 1234:4321
    """
    return ip.strip("[]")

def checkIP6(ip):
    """ Check IPv6 address.
    
    @param ip address string
    @return True if address is valid, else False
    """

    try:
        socket.inet_pton(socket.AF_INET6, normalizeIP6(ip))
    except socket.error:
        return False
    return True

def checkIPnMask(ip):
    if "/" in ip:
        addr = ip[:ip.index("/")]
        mask = ip[ip.index("/")+1:]
        if len(addr) < 1 or len(mask) < 1:
            return False
    else:
        addr = ip
        mask = None
    if not checkIP(addr):
        return False
    if mask:
        if "." in mask:
            return checkIP(mask)
        else:
            try:
                i = int(mask)
            except ValueError:
                return False
            if i < 0 or i > 32:
                return False
    return True

def checkIP6nMask(ip):
    if "/" in ip:
        addr = ip[:ip.index("/")]
        mask = ip[ip.index("/")+1:]
        if len(addr) < 1 or len(mask) < 1:
            return False
    else:
        addr = ip
        mask = None
    if not checkIP6(addr):
        return False
    if mask:
        try:
            i = int(mask)
        except ValueError:
            return False
        if i < 0 or i > 128:
            return False

    return True

def checkProtocol(protocol):
    try:
        i = int(protocol)
    except ValueError:
        # string
        try:
            socket.getprotobyname(protocol)
        except socket.error:
            return False
    else:
        if i < 0 or i > 255:
            return False

    return True

def checkInterface(iface):
    """ Check interface string

    @param interface string
    @return True if interface is valid (maximum 16 chars and does not contain ' ', '/', '!', ':', '*'), else False
    """

    if not iface or len(iface) > 16:
        return False
    for ch in [ ' ', '/', '!', '*' ]:
        # !:* are limits for iptables <= 1.4.5
        if ch in iface:
            return False
    # disabled old iptables check
    #if iface == "+":
    #    # limit for iptables <= 1.4.5
    #    return False
    return True

def checkUINT32(val):
    try:
        x = int(val, 0)
    except ValueError:
        return False
    else:
        if x >= 0 and x <= 4294967295:
            return True
    return False

def firewalld_is_active():
    """ Check if firewalld is active

    @return True if there is a firewalld pid file and the pid is used by firewalld
    """

    if not os.path.exists(FIREWALLD_PIDFILE):
        return False

    try:
        with open(FIREWALLD_PIDFILE, "r") as fd:
            pid = fd.readline()
    except Exception:
        return False

    if not os.path.exists("/proc/%s" % pid):
        return False

    try:
        with open("/proc/%s/cmdline" % pid, "r") as fd:
            cmdline = fd.readline()
    except Exception:
        return False

    if "firewalld" in cmdline:
        return True

    return False

def tempFile():
    try:
        if not os.path.exists(FIREWALLD_TEMPDIR):
            os.mkdir(FIREWALLD_TEMPDIR, 0o750)

        return tempfile.NamedTemporaryFile(mode='wt', prefix="temp.",
                                           dir=FIREWALLD_TEMPDIR, delete=False)
    except Exception as msg:
        log.error("Failed to create temporary file: %s" % msg)
        raise
    return None

def readfile(filename):
    try:
        with open(filename, "r") as f:
            return f.readlines()
    except Exception as e:
        log.error('Failed to read file "%s": %s' % (filename, e))
    return None

def writefile(filename, line):
    try:
        with open(filename, "w") as f:
            f.write(line)
    except Exception as e:
        log.error('Failed to write to file "%s": %s' % (filename, e))
        return False
    return True

def enable_ip_forwarding(ipv):
    if ipv == "ipv4":
        return writefile("/proc/sys/net/ipv4/ip_forward", "1\n")
    elif ipv == "ipv6":
        return writefile("/proc/sys/net/ipv6/conf/all/forwarding", "1\n")
    return False

def get_nf_conntrack_short_name(module):
    return module.replace("_","-").replace("nf-conntrack-", "")

def get_nf_conntrack_helper_setting():
    try:
        return int(readfile("/proc/sys/net/netfilter/nf_conntrack_helper")[0])
    except Exception:
        log.warning("Failed to get and parse nf_conntrack_helper setting")
        return 0

def set_nf_conntrack_helper_setting(flag):
    return writefile("/proc/sys/net/netfilter/nf_conntrack_helper",
                     "1\n" if flag else "0\n")

def check_port(port):
    _range = getPortRange(port)
    if _range == -2 or _range == -1 or _range is None or \
            (len(_range) == 2 and _range[0] >= _range[1]):
        if _range == -2:
            log.debug2("'%s': port > 65535" % port)
        elif _range == -1:
            log.debug2("'%s': port is invalid" % port)
        elif _range is None:
            log.debug2("'%s': port is ambiguous" % port)
        elif len(_range) == 2 and _range[0] >= _range[1]:
            log.debug2("'%s': range start >= end" % port)
        return False
    return True

def check_address(ipv, source):
    if ipv == "ipv4":
        return checkIPnMask(source)
    elif ipv == "ipv6":
        return checkIP6nMask(source)
    else:
        return False

def check_single_address(ipv, source):
    if ipv == "ipv4":
        return checkIP(source)
    elif ipv == "ipv6":
        return checkIP6(source)
    else:
        return False

def check_mac(mac):
    if len(mac) == 12+5:
        # 0 1 : 3 4 : 6 7 : 9 10 : 12 13 : 15 16
        for i in (2, 5, 8, 11, 14):
            if mac[i] != ":":
                return False
        for i in (0, 1, 3, 4, 6, 7, 9, 10, 12, 13, 15, 16):
            if mac[i] not in string.hexdigits:
                return False
        return True
    return False

def uniqify(_list):
    # removes duplicates from list, whilst preserving order
    output = []
    for x in _list:
        if x not in output:
            output.append(x)
    return output

def ppid_of_pid(pid):
    """ Get parent for pid """
    try:
        f = os.popen("ps -o ppid -h -p %d 2>/dev/null" % pid)
        pid = int(f.readlines()[0].strip())
        f.close()
    except Exception:
        return None
    return pid

def max_zone_name_len():
    """
    Netfilter limits length of chain to (currently) 28 chars.
    The longest chain we create is FWDI_<zone>_allow,
    which leaves 28 - 11 = 17 chars for <zone>.
    """
    from firewall.core.base import SHORTCUTS
    longest_shortcut = max(map(len, SHORTCUTS.values()))
    return 28 - (longest_shortcut + len("__allow"))

def checkUser(user):
    if len(user) < 1 or len(user) > os.sysconf('SC_LOGIN_NAME_MAX'):
        return False
    for c in user:
        if c not in string.ascii_letters and \
           c not in string.digits and \
           c not in [ ".", "-", "_", "$" ]:
            return False
    return True

def checkUid(uid):
    if isinstance(uid, str):
        try:
            uid = int(uid)
        except ValueError:
            return False
    if uid >= 0 and uid <= 2**31-1:
        return True
    return False

def checkCommand(command):
    if len(command) < 1 or len(command) > 1024:
        return False
    for ch in [ "|", "\n", "\0" ]:
        if ch in command:
            return False
    if command[0] != "/":
        return False
    return True

def checkContext(context):
    splits = context.split(":")
    if len(splits) not in [4, 5]:
        return False
    # user ends with _u if not root
    if splits[0] != "root" and splits[0][-2:] != "_u":
        return False
    # role ends with _r
    if splits[1][-2:] != "_r":
        return False
    # type ends with _t
    if splits[2][-2:] != "_t":
        return False
    # level might also contain :
    if len(splits[3]) < 1:
        return False
    return True

def joinArgs(args):
    if "quote" in dir(shlex):
        return " ".join(shlex.quote(a) for a in args)
    else:
        return " ".join(pipes.quote(a) for a in args)

def splitArgs(_string):
    if PY2 and isinstance(_string, unicode): # noqa: F821
        # Python2's shlex doesn't like unicode
        _string = u2b(_string)
        splits = shlex.split(_string)
        return map(b2u, splits)
    else:
        return shlex.split(_string)

def b2u(_string):
    """ bytes to unicode """
    if isinstance(_string, bytes):
        return _string.decode('UTF-8', 'replace')
    return _string

def u2b(_string):
    """ unicode to bytes """
    if not isinstance(_string, bytes):
        return _string.encode('UTF-8', 'replace')
    return _string

def u2b_if_py2(_string):
    """ unicode to bytes only if Python 2"""
    if PY2 and isinstance(_string, unicode): # noqa: F821
        return _string.encode('UTF-8', 'replace')
    return _string