text: ## This file is part of Scapy
  ## See http://www.secdev.org/projects/scapy for more informations
  ## Copyright (C) Philippe Biondi <phil@secdev.org>
  ## Copyright (C) 6WIND <olivier.matz@6wind.com>
  ## This program is published under a GPLv2 license
  
  """
  SCTP (Stream Control Transmission Protocol).
  """
  
  import struct
  
  from scapy.packet import *
  from scapy.fields import *
  from scapy.layers.inet import IP
  from scapy.layers.inet6 import IP6Field
  
  IPPROTO_SCTP=132
  
  # crc32-c (Castagnoli) (crc32c_poly=0x1EDC6F41)
  crc32c_table = [
      0x00000000, 0xF26B8303, 0xE13B70F7, 0x1350F3F4,
      0xC79A971F, 0x35F1141C, 0x26A1E7E8, 0xD4CA64EB,
      0x8AD958CF, 0x78B2DBCC, 0x6BE22838, 0x9989AB3B,
      0x4D43CFD0, 0xBF284CD3, 0xAC78BF27, 0x5E133C24,
      0x105EC76F, 0xE235446C, 0xF165B798, 0x030E349B,
      0xD7C45070, 0x25AFD373, 0x36FF2087, 0xC494A384,
      0x9A879FA0, 0x68EC1CA3, 0x7BBCEF57, 0x89D76C54,
      0x5D1D08BF, 0xAF768BBC, 0xBC267848, 0x4E4DFB4B,
      0x20BD8EDE, 0xD2D60DDD, 0xC186FE29, 0x33ED7D2A,
      0xE72719C1, 0x154C9AC2, 0x061C6936, 0xF477EA35,
      0xAA64D611, 0x580F5512, 0x4B5FA6E6, 0xB93425E5,
      0x6DFE410E, 0x9F95C20D, 0x8CC531F9, 0x7EAEB2FA,
      0x30E349B1, 0xC288CAB2, 0xD1D83946, 0x23B3BA45,
      0xF779DEAE, 0x05125DAD, 0x1642AE59, 0xE4292D5A,
      0xBA3A117E, 0x4851927D, 0x5B016189, 0xA96AE28A,
      0x7DA08661, 0x8FCB0562, 0x9C9BF696, 0x6EF07595,
      0x417B1DBC, 0xB3109EBF, 0xA0406D4B, 0x522BEE48,
      0x86E18AA3, 0x748A09A0, 0x67DAFA54, 0x95B17957,
      0xCBA24573, 0x39C9C670, 0x2A993584, 0xD8F2B687,
      0x0C38D26C, 0xFE53516F, 0xED03A29B, 0x1F682198,
      0x5125DAD3, 0xA34E59D0, 0xB01EAA24, 0x42752927,
      0x96BF4DCC, 0x64D4CECF, 0x77843D3B, 0x85EFBE38,
      0xDBFC821C, 0x2997011F, 0x3AC7F2EB, 0xC8AC71E8,
      0x1C661503, 0xEE0D9600, 0xFD5D65F4, 0x0F36E6F7,
      0x61C69362, 0x93AD1061, 0x80FDE395, 0x72966096,
      0xA65C047D, 0x5437877E, 0x4767748A, 0xB50CF789,
      0xEB1FCBAD, 0x197448AE, 0x0A24BB5A, 0xF84F3859,
      0x2C855CB2, 0xDEEEDFB1, 0xCDBE2C45, 0x3FD5AF46,
      0x7198540D, 0x83F3D70E, 0x90A324FA, 0x62C8A7F9,
      0xB602C312, 0x44694011, 0x5739B3E5, 0xA55230E6,
      0xFB410CC2, 0x092A8FC1, 0x1A7A7C35, 0xE811FF36,
      0x3CDB9BDD, 0xCEB018DE, 0xDDE0EB2A, 0x2F8B6829,
      0x82F63B78, 0x709DB87B, 0x63CD4B8F, 0x91A6C88C,
      0x456CAC67, 0xB7072F64, 0xA457DC90, 0x563C5F93,
      0x082F63B7, 0xFA44E0B4, 0xE9141340, 0x1B7F9043,
      0xCFB5F4A8, 0x3DDE77AB, 0x2E8E845F, 0xDCE5075C,
      0x92A8FC17, 0x60C37F14, 0x73938CE0, 0x81F80FE3,
      0x55326B08, 0xA759E80B, 0xB4091BFF, 0x466298FC,
      0x1871A4D8, 0xEA1A27DB, 0xF94AD42F, 0x0B21572C,
      0xDFEB33C7, 0x2D80B0C4, 0x3ED04330, 0xCCBBC033,
      0xA24BB5A6, 0x502036A5, 0x4370C551, 0xB11B4652,
      0x65D122B9, 0x97BAA1BA, 0x84EA524E, 0x7681D14D,
      0x2892ED69, 0xDAF96E6A, 0xC9A99D9E, 0x3BC21E9D,
      0xEF087A76, 0x1D63F975, 0x0E330A81, 0xFC588982,
      0xB21572C9, 0x407EF1CA, 0x532E023E, 0xA145813D,
      0x758FE5D6, 0x87E466D5, 0x94B49521, 0x66DF1622,
      0x38CC2A06, 0xCAA7A905, 0xD9F75AF1, 0x2B9CD9F2,
      0xFF56BD19, 0x0D3D3E1A, 0x1E6DCDEE, 0xEC064EED,
      0xC38D26C4, 0x31E6A5C7, 0x22B65633, 0xD0DDD530,
      0x0417B1DB, 0xF67C32D8, 0xE52CC12C, 0x1747422F,
      0x49547E0B, 0xBB3FFD08, 0xA86F0EFC, 0x5A048DFF,
      0x8ECEE914, 0x7CA56A17, 0x6FF599E3, 0x9D9E1AE0,
      0xD3D3E1AB, 0x21B862A8, 0x32E8915C, 0xC083125F,
      0x144976B4, 0xE622F5B7, 0xF5720643, 0x07198540,
      0x590AB964, 0xAB613A67, 0xB831C993, 0x4A5A4A90,
      0x9E902E7B, 0x6CFBAD78, 0x7FAB5E8C, 0x8DC0DD8F,
      0xE330A81A, 0x115B2B19, 0x020BD8ED, 0xF0605BEE,
      0x24AA3F05, 0xD6C1BC06, 0xC5914FF2, 0x37FACCF1,
      0x69E9F0D5, 0x9B8273D6, 0x88D28022, 0x7AB90321,
      0xAE7367CA, 0x5C18E4C9, 0x4F48173D, 0xBD23943E,
      0xF36E6F75, 0x0105EC76, 0x12551F82, 0xE03E9C81,
      0x34F4F86A, 0xC69F7B69, 0xD5CF889D, 0x27A40B9E,
      0x79B737BA, 0x8BDCB4B9, 0x988C474D, 0x6AE7C44E,
      0xBE2DA0A5, 0x4C4623A6, 0x5F16D052, 0xAD7D5351,
      ]
  
  def crc32c(buf):
      crc = 0xffffffff
      for c in buf:
          #crc = (crc>>8) ^ crc32c_table[(crc^(ord(c))) & 0xFF]
          crc = (crc>>8) ^ crc32c_table[(crc^(c)) & 0xFF]
      crc = (~crc) & 0xffffffff
      # reverse endianness
      return struct.unpack(">I",struct.pack("<I", crc))[0]
  
  # old checksum (RFC2960)
  """
  BASE = 65521 # largest prime smaller than 65536
  def update_adler32(adler, buf):
      s1 = adler & 0xffff
      s2 = (adler >> 16) & 0xffff
      print(s1,s2)
  
      for c in buf:
          print(ord(c))
          s1 = (s1 + ord(c)) % BASE
          s2 = (s2 + s1) % BASE
          print(s1,s2)
      return (s2 << 16) + s1
  
  def sctp_checksum(buf):
      return update_adler32(1, buf)
  """
  
  sctpchunktypescls = {
      0 : "SCTPChunkData",
      1 : "SCTPChunkInit",
      2 : "SCTPChunkInitAck",
      3 : "SCTPChunkSACK",
      4 : "SCTPChunkHeartbeatReq",
      5 : "SCTPChunkHeartbeatAck",
      6 : "SCTPChunkAbort",
      7 : "SCTPChunkShutdown",
      8 : "SCTPChunkShutdownAck",
      9 : "SCTPChunkError",
      10 : "SCTPChunkCookieEcho",
      11 : "SCTPChunkCookieAck",
      14 : "SCTPChunkShutdownComplete",
      }
  
  sctpchunktypes = {
      0 : "data",
      1 : "init",
      2 : "init-ack",
      3 : "sack",
      4 : "heartbeat-req",
      5 : "heartbeat-ack",
      6 : "abort",
      7 : "shutdown",
      8 : "shutdown-ack",
      9 : "error",
      10 : "cookie-echo",
      11 : "cookie-ack",
      14 : "shutdown-complete",
      }
  
  sctpchunkparamtypescls = {
      1 : "SCTPChunkParamHearbeatInfo",
      5 : "SCTPChunkParamIPv4Addr",
      6 : "SCTPChunkParamIPv6Addr",
      7 : "SCTPChunkParamStateCookie",
      8 : "SCTPChunkParamUnrocognizedParam",
      9 : "SCTPChunkParamCookiePreservative",
      11 : "SCTPChunkParamHostname",
      12 : "SCTPChunkParamSupportedAddrTypes",
      32768 : "SCTPChunkParamECNCapable",
      49152 : "SCTPChunkParamFwdTSN",
      49158 : "SCTPChunkParamAdaptationLayer",
      }
  
  sctpchunkparamtypes = {
      1 : "heartbeat-info",
      5 : "IPv4",
      6 : "IPv6",
      7 : "state-cookie",
      8 : "unrecognized-param",
      9 : "cookie-preservative",
      11 : "hostname",
      12 : "addrtypes",
      32768 : "ecn-capable",
      49152 : "fwd-tsn-supported",
      49158 : "adaptation-layer",
      }
  
  ############## SCTP header
  
  # Dummy class to guess payload type (variable parameters)
  class _SCTPChunkGuessPayload:
      def default_payload_class(self,p):
          if len(p) < 4:
              return conf.padding_layer
          else:
              t = p[0]
              return globals().get(sctpchunktypescls.get(t, "Raw"), conf.raw_layer)
  
  
  class SCTP(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ShortField("sport", None),
                      ShortField("dport", None),
                      XIntField("tag", None),
                      XIntField("chksum", None), ]
      def answers(self, other):
          if not isinstance(other, SCTP):
              return 0
          if conf.checkIPsrc:
              if not ((self.sport == other.dport) and
                      (self.dport == other.sport)):
                  return 0
          return 1
      def post_build(self, p, pay):
          p += pay
          if self.chksum is None:
              crc = crc32c(str(p))
              p = p[:8]+struct.pack(">I", crc)+p[12:]
          return p
  
  ############## SCTP Chunk variable params
  
  class ChunkParamField(PacketListField):
      islist = 1
      holds_packets=1
      def __init__(self, name, default, count_from=None, length_from=None):
          PacketListField.__init__(self, name, default, conf.raw_layer, count_from=count_from, length_from=length_from)
      def m2i(self, p, m):
          cls = conf.raw_layer
          if len(m) >= 4:
              #t = ord(m[0]) * 256 + ord(m[1])
              t = (m[0]) * 256 + (m[1])
              cls = globals().get(sctpchunkparamtypescls.get(t, "Raw"), conf.raw_layer)
          return cls(m)
  
  # dummy class to avoid Raw() after Chunk params
  class _SCTPChunkParam:
      def extract_padding(self, s):
          return b"",s[:]
  
  class SCTPChunkParamHearbeatInfo(_SCTPChunkParam, Packet):
      fields_desc = [ ShortEnumField("type", 1, sctpchunkparamtypes),
                      FieldLenField("len", None, length_of="data",
                                    adjust = lambda pkt,x:x+4),
                      PadField(StrLenField("data", b"",
                                           length_from=lambda pkt: pkt.len-4),
                               4, padwith=b"\x00"),]
  
  class SCTPChunkParamIPv4Addr(_SCTPChunkParam, Packet):
      fields_desc = [ ShortEnumField("type", 5, sctpchunkparamtypes),
                      ShortField("len", 8),
                      IPField("addr","127.0.0.1"), ]
  
  class SCTPChunkParamIPv6Addr(_SCTPChunkParam, Packet):
      fields_desc = [ ShortEnumField("type", 6, sctpchunkparamtypes),
                      ShortField("len", 20),
                      IP6Field("addr","::1"), ]
  
  class SCTPChunkParamStateCookie(_SCTPChunkParam, Packet):
      fields_desc = [ ShortEnumField("type", 7, sctpchunkparamtypes),
                      FieldLenField("len", None, length_of="cookie",
                                    adjust = lambda pkt,x:x+4),
                      PadField(StrLenField("cookie", b"",
                                           length_from=lambda pkt: pkt.len-4),
                               4, padwith=b"\x00"),]
  
  class SCTPChunkParamUnrocognizedParam(_SCTPChunkParam, Packet):
      fields_desc = [ ShortEnumField("type", 8, sctpchunkparamtypes),
                      FieldLenField("len", None, length_of="param",
                                    adjust = lambda pkt,x:x+4),
                      PadField(StrLenField("param", b"",
                                           length_from=lambda pkt: pkt.len-4),
                               4, padwith=b"\x00"),]
  
  class SCTPChunkParamCookiePreservative(_SCTPChunkParam, Packet):
      fields_desc = [ ShortEnumField("type", 9, sctpchunkparamtypes),
                      ShortField("len", 8),
                      XIntField("sug_cookie_inc", None), ]
  
  class SCTPChunkParamHostname(_SCTPChunkParam, Packet):
      fields_desc = [ ShortEnumField("type", 11, sctpchunkparamtypes),
                      FieldLenField("len", None, length_of="hostname",
                                    adjust = lambda pkt,x:x+4),
                      PadField(StrLenField("hostname", b"",
                                           length_from=lambda pkt: pkt.len-4),
                               4, padwith=b"\x00"), ]
  
  class SCTPChunkParamSupportedAddrTypes(_SCTPChunkParam, Packet):
      fields_desc = [ ShortEnumField("type", 12, sctpchunkparamtypes),
                      FieldLenField("len", None, length_of="addr_type_list",
                                    adjust = lambda pkt,x:x+4),
                      PadField(FieldListField("addr_type_list", [ "IPv4" ],
                                              ShortEnumField("addr_type", 5, sctpchunkparamtypes),
                                              length_from=lambda pkt: pkt.len-4),
                               4, padwith=b"\x00"), ]
  
  class SCTPChunkParamECNCapable(_SCTPChunkParam, Packet):
      fields_desc = [ ShortEnumField("type", 32768, sctpchunkparamtypes),
                      ShortField("len", 4), ]
  
  class SCTPChunkParamFwdTSN(_SCTPChunkParam, Packet):
      fields_desc = [ ShortEnumField("type", 49152, sctpchunkparamtypes),
                      ShortField("len", 4), ]
  
  class SCTPChunkParamAdaptationLayer(_SCTPChunkParam, Packet):
      fields_desc = [ ShortEnumField("type", 49158, sctpchunkparamtypes),
                      ShortField("len", 8),
                      XIntField("indication", None), ]
  
  ############## SCTP Chunks
  
  class SCTPChunkData(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 0, sctpchunktypes),
                      BitField("reserved", None, 4),
                      BitField("delay_sack", 0, 1),
                      BitField("unordered", 0, 1),
                      BitField("beginning", 0, 1),
                      BitField("ending", 0, 1),
                      FieldLenField("len", None, length_of="data", adjust = lambda pkt,x:x+16),
                      XIntField("tsn", None),
                      XShortField("stream_id", None),
                      XShortField("stream_seq", None),
                      XIntField("proto_id", None),
                      PadField(StrLenField("data", None, length_from=lambda pkt: pkt.len-16),
                               4, padwith=b"\x00"),
                      ]
  
  class SCTPChunkInit(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 1, sctpchunktypes),
                      XByteField("flags", None),
                      FieldLenField("len", None, length_of="params", adjust = lambda pkt,x:x+20),
                      XIntField("init_tag", None),
                      IntField("a_rwnd", None),
                      ShortField("n_out_streams", None),
                      ShortField("n_in_streams", None),
                      XIntField("init_tsn", None),
                      ChunkParamField("params", None, length_from=lambda pkt:pkt.len-20),
                      ]
  
  class SCTPChunkInitAck(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 2, sctpchunktypes),
                      XByteField("flags", None),
                      FieldLenField("len", None, length_of="params", adjust = lambda pkt,x:x+20),
                      XIntField("init_tag", None),
                      IntField("a_rwnd", None),
                      ShortField("n_out_streams", None),
                      ShortField("n_in_streams", None),
                      XIntField("init_tsn", None),
                      ChunkParamField("params", None, length_from=lambda pkt:pkt.len-20),
                      ]
  
  class GapAckField(Field):
      def __init__(self, name, default):
          Field.__init__(self, name, default, "4s")
      def i2m(self, pkt, x):
          if x is None:
              return "\0\0\0\0"
          sta, end = map(int, x.split(":"))
          args = tuple([">HH", sta, end])
          return struct.pack(*args)
      def m2i(self, pkt, x):
          return "%d:%d"%(struct.unpack(">HH", x))
      def any2i(self, pkt, x):
          if type(x) is tuple and len(x) == 2:
              return "%d:%d"%(x)
          return x
  
  class SCTPChunkSACK(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 3, sctpchunktypes),
                      XByteField("flags", None),
                      ShortField("len", None),
                      XIntField("cumul_tsn_ack", None),
                      IntField("a_rwnd", None),
                      FieldLenField("n_gap_ack", None, count_of="gap_ack_list"),
                      FieldLenField("n_dup_tsn", None, count_of="dup_tsn_list"),
                      FieldListField("gap_ack_list", [ ], GapAckField("gap_ack", None), count_from=lambda pkt:pkt.n_gap_ack),
                      FieldListField("dup_tsn_list", [ ], XIntField("dup_tsn", None), count_from=lambda pkt:pkt.n_dup_tsn),
                      ]
  
      def post_build(self, p, pay):
          if self.len is None:
              p = p[:2] + struct.pack(">H", len(p)) + p[4:]
          return p+pay
  
  
  class SCTPChunkHeartbeatReq(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 4, sctpchunktypes),
                      XByteField("flags", None),
                      FieldLenField("len", None, length_of="params", adjust = lambda pkt,x:x+4),
                      ChunkParamField("params", None, length_from=lambda pkt:pkt.len-4),
                     ]
  
  class SCTPChunkHeartbeatAck(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 5, sctpchunktypes),
                      XByteField("flags", None),
                      FieldLenField("len", None, length_of="params", adjust = lambda pkt,x:x+4),
                      ChunkParamField("params", None, length_from=lambda pkt:pkt.len-4),
                     ]
  
  class SCTPChunkAbort(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 6, sctpchunktypes),
                      BitField("reserved", None, 7),
                      BitField("TCB", 0, 1),
                      FieldLenField("len", None, length_of="error_causes", adjust = lambda pkt,x:x+4),
                      PadField(StrLenField("error_causes", b"", length_from=lambda pkt: pkt.len-4),
                               4, padwith=b"\x00"),
                     ]
  
  class SCTPChunkShutdown(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 7, sctpchunktypes),
                      XByteField("flags", None),
                      ShortField("len", 8),
                      XIntField("cumul_tsn_ack", None),
                     ]
  
  class SCTPChunkShutdownAck(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 8, sctpchunktypes),
                      XByteField("flags", None),
                      ShortField("len", 4),
                     ]
  
  class SCTPChunkError(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 9, sctpchunktypes),
                      XByteField("flags", None),
                      FieldLenField("len", None, length_of="error_causes", adjust = lambda pkt,x:x+4),
                      PadField(StrLenField("error_causes", b"", length_from=lambda pkt: pkt.len-4),
                               4, padwith=b"\x00"),
                     ]
  
  class SCTPChunkCookieEcho(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 10, sctpchunktypes),
                      XByteField("flags", None),
                      FieldLenField("len", None, length_of="cookie", adjust = lambda pkt,x:x+4),
                      PadField(StrLenField("cookie", b"", length_from=lambda pkt: pkt.len-4),
                               4, padwith=b"\x00"),
                     ]
  
  class SCTPChunkCookieAck(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 11, sctpchunktypes),
                      XByteField("flags", None),
                      ShortField("len", 4),
                     ]
  
  class SCTPChunkShutdownComplete(_SCTPChunkGuessPayload, Packet):
      fields_desc = [ ByteEnumField("type", 12, sctpchunktypes),
                      BitField("reserved", None, 7),
                      BitField("TCB", 0, 1),
                      ShortField("len", 4),
                      ]
  
  bind_layers( IP,           SCTP,          proto=IPPROTO_SCTP)
  
  