# $Id: icmp.py 45 2007-08-03 00:05:22Z jon.oberheide $
# -*- coding: utf-8 -*-
"""Internet Control Message Protocol."""
from __future__ import print_function
from __future__ import absolute_import

from . import dpkt

# Types (icmp_type) and codes (icmp_code) -
# http://www.iana.org/assignments/icmp-parameters

ICMP_CODE_NONE = 0  # for types without codes
ICMP_ECHOREPLY = 0  # echo reply
ICMP_UNREACH = 3  # dest unreachable, codes:
ICMP_UNREACH_NET = 0  # bad net
ICMP_UNREACH_HOST = 1  # bad host
ICMP_UNREACH_PROTO = 2  # bad protocol
ICMP_UNREACH_PORT = 3  # bad port
ICMP_UNREACH_NEEDFRAG = 4  # IP_DF caused drop
ICMP_UNREACH_SRCFAIL = 5  # src route failed
ICMP_UNREACH_NET_UNKNOWN = 6  # unknown net
ICMP_UNREACH_HOST_UNKNOWN = 7  # unknown host
ICMP_UNREACH_ISOLATED = 8  # src host isolated
ICMP_UNREACH_NET_PROHIB = 9  # for crypto devs
ICMP_UNREACH_HOST_PROHIB = 10  # ditto
ICMP_UNREACH_TOSNET = 11  # bad tos for net
ICMP_UNREACH_TOSHOST = 12  # bad tos for host
ICMP_UNREACH_FILTER_PROHIB = 13  # prohibited access
ICMP_UNREACH_HOST_PRECEDENCE = 14  # precedence error
ICMP_UNREACH_PRECEDENCE_CUTOFF = 15  # precedence cutoff
ICMP_SRCQUENCH = 4  # packet lost, slow down
ICMP_REDIRECT = 5  # shorter route, codes:
ICMP_REDIRECT_NET = 0  # for network
ICMP_REDIRECT_HOST = 1  # for host
ICMP_REDIRECT_TOSNET = 2  # for tos and net
ICMP_REDIRECT_TOSHOST = 3  # for tos and host
ICMP_ALTHOSTADDR = 6  # alternate host address
ICMP_ECHO = 8  # echo service
ICMP_RTRADVERT = 9  # router advertise, codes:
ICMP_RTRADVERT_NORMAL = 0  # normal
ICMP_RTRADVERT_NOROUTE_COMMON = 16  # selective routing
ICMP_RTRSOLICIT = 10  # router solicitation
ICMP_TIMEXCEED = 11  # time exceeded, code:
ICMP_TIMEXCEED_INTRANS = 0  # ttl==0 in transit
ICMP_TIMEXCEED_REASS = 1  # ttl==0 in reass
ICMP_PARAMPROB = 12  # ip header bad
ICMP_PARAMPROB_ERRATPTR = 0  # req. opt. absent
ICMP_PARAMPROB_OPTABSENT = 1  # req. opt. absent
ICMP_PARAMPROB_LENGTH = 2  # bad length
ICMP_TSTAMP = 13  # timestamp request
ICMP_TSTAMPREPLY = 14  # timestamp reply
ICMP_INFO = 15  # information request
ICMP_INFOREPLY = 16  # information reply
ICMP_MASK = 17  # address mask request
ICMP_MASKREPLY = 18  # address mask reply
ICMP_TRACEROUTE = 30  # traceroute
ICMP_DATACONVERR = 31  # data conversion error
ICMP_MOBILE_REDIRECT = 32  # mobile host redirect
ICMP_IP6_WHEREAREYOU = 33  # IPv6 where-are-you
ICMP_IP6_IAMHERE = 34  # IPv6 i-am-here
ICMP_MOBILE_REG = 35  # mobile registration req
ICMP_MOBILE_REGREPLY = 36  # mobile registration reply
ICMP_DNS = 37  # domain name request
ICMP_DNSREPLY = 38  # domain name reply
ICMP_SKIP = 39  # SKIP
ICMP_PHOTURIS = 40  # Photuris
ICMP_PHOTURIS_UNKNOWN_INDEX = 0  # unknown sec index
ICMP_PHOTURIS_AUTH_FAILED = 1  # auth failed
ICMP_PHOTURIS_DECOMPRESS_FAILED = 2  # decompress failed
ICMP_PHOTURIS_DECRYPT_FAILED = 3  # decrypt failed
ICMP_PHOTURIS_NEED_AUTHN = 4  # no authentication
ICMP_PHOTURIS_NEED_AUTHZ = 5  # no authorization
ICMP_TYPE_MAX = 40


class ICMP(dpkt.Packet):
    """Internet Control Message Protocol.

    The Internet Control Message Protocol (ICMP) is a supporting protocol in the Internet protocol suite.
    It is used by network devices, including routers, to send error messages and operational information
    indicating success or failure when communicating with another IP address.

    Attributes:
        __hdr__: Header fields of ICMP.
            type: (int): ICMP type (1 byte)
            code: (int): ICMP subtype (1 byte)
            sum: (int): Internet checksum (RFC 1071) for error checking,
                calculated from the ICMP header and data with value 0 substituted for this field. (2 bytes)
    """

    __hdr__ = (
        ('type', 'B', 8),
        ('code', 'B', 0),
        ('sum', 'H', 0)
    )

    class Echo(dpkt.Packet):
        __hdr__ = (('id', 'H', 0), ('seq', 'H', 0))

    class Quote(dpkt.Packet):
        __hdr__ = (('pad', 'I', 0),)

        def unpack(self, buf):
            dpkt.Packet.unpack(self, buf)
            from . import ip
            self.data = self.ip = ip.IP(self.data)

    class Unreach(Quote):
        __hdr__ = (('pad', 'H', 0), ('mtu', 'H', 0))

    class Quench(Quote):
        pass

    class Redirect(Quote):
        __hdr__ = (('gw', 'I', 0),)

    class ParamProbe(Quote):
        __hdr__ = (('ptr', 'B', 0), ('pad1', 'B', 0), ('pad2', 'H', 0))

    class TimeExceed(Quote):
        pass

    _typesw = {0: Echo, 3: Unreach, 4: Quench, 5: Redirect, 8: Echo, 11: TimeExceed}

    def unpack(self, buf):
        dpkt.Packet.unpack(self, buf)
        try:
            self.data = self._typesw[self.type](self.data)
            setattr(self, self.data.__class__.__name__.lower(), self.data)
        except (KeyError, dpkt.UnpackError):
            pass

    def __bytes__(self):
        if not self.sum:
            self.sum = dpkt.in_cksum(dpkt.Packet.__bytes__(self))
        return dpkt.Packet.__bytes__(self)


def test_icmp():
    s = (
        b'\x03\x0a\x6b\x19\x00\x00\x00\x00\x45\x00\x00\x28\x94\x1f\x00\x00\xe3\x06\x99\xb4\x23\x2b'
        b'\x24\x00\xde\x8e\x84\x42\xab\xd1\x00\x50\x00\x35\xe1\x29\x20\xd9\x00\x00\x00\x22\x9b\xf0'
        b'\xe2\x04\x65\x6b'
    )
    r = ICMP(s)
    assert bytes(r) == s

    # construction
    s = (
        b'\x00\x00\x53\x87\x00\x01\x03\xd6\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e'
        b'\x4f\x50\x51\x52\x53\x54\x55\x56\x57\x41\x42\x43\x44\x45\x46\x47\x48\x49'
    )
    p = ICMP(
        type=0,
        sum=0x5387,
        data=ICMP.Echo(
            id=1,
            seq=0x03d6,
            data=b'ABCDEFGHIJKLMNOPQRSTUVWABCDEFGHI'
        )
    )
    assert bytes(p) == s

    # test checksum
    p = ICMP(
        type=0,
        data=ICMP.Echo(
            id=1,
            seq=0x03d6,
            data=b'ABCDEFGHIJKLMNOPQRSTUVWABCDEFGHI'
        )
    )
    assert bytes(p) == s
    assert p.sum == 0x5387


def test_invalid_data():
    from binascii import unhexlify

    buf = unhexlify(
        '01'    # type (invalid entry)
        '00'    # code
        '0000'  # sum

        'abcd'  # data
    )
    icmp = ICMP(buf)

    # no additional attributes have been added due to the type being invalid
    assert dir(icmp) == dir(ICMP())