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Fix GTP_U_Header binds #2010

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Merged
merged 1 commit into from
May 3, 2019
Merged

Fix GTP_U_Header binds #2010

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33 changes: 26 additions & 7 deletions scapy/contrib/gtp.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,9 +22,11 @@
IPField, PacketListField, ShortField, StrFixedLenField, StrLenField, \
XBitField, XByteField, XIntField
from scapy.layers.inet import IP, UDP
from scapy.layers.inet6 import IP6Field
from scapy.layers.inet6 import IPv6, IP6Field
from scapy.layers.ppp import PPP
from scapy.modules.six.moves import range
from scapy.packet import bind_layers, Packet, Raw
from scapy.packet import bind_layers, bind_bottom_up, bind_top_down, \
Packet, Raw
from scapy.volatile import RandInt, RandIP, RandNum, RandString


Expand Down Expand Up @@ -254,6 +256,19 @@ class GTP_U_Header(GTPHeader):
# encapsulated in G-PDUs. A G-PDU is a packet including a GTP-U header and a T-PDU. The Path Protocol # noqa: E501
# defines the path and the GTP-U header defines the tunnel. Several tunnels may be multiplexed on a single path. # noqa: E501

def guess_payload_class(self, payload):
# Snooped from Wireshark
# https://github.com/boundary/wireshark/blob/07eade8124fd1d5386161591b52e177ee6ea849f/epan/dissectors/packet-gtp.c#L8195 # noqa: E501
if self.gtp_type == 255:
sub_proto = orb(payload[0])
if sub_proto >= 0x45 and sub_proto <= 0x4e:
return IP
elif (sub_proto & 0xf0) == 0x60:
return IPv6
else:
return PPP
return GTPHeader.guess_payload_class(self, payload)


# Some gtp_types have to be associated with a certain type of header
GTPforcedTypes = {
Expand Down Expand Up @@ -887,8 +902,9 @@ class GTPmorethan1500(Packet):


# Bind GTP-C
bind_layers(UDP, GTPHeader, dport=2123)
bind_layers(UDP, GTPHeader, sport=2123)
bind_bottom_up(UDP, GTPHeader, dport=2123)
bind_bottom_up(UDP, GTPHeader, sport=2123)
bind_layers(UDP, GTPHeader, dport=2123, sport=2123)
bind_layers(GTPHeader, GTPEchoRequest, gtp_type=1, S=1)
bind_layers(GTPHeader, GTPEchoResponse, gtp_type=2, S=1)
bind_layers(GTPHeader, GTPCreatePDPContextRequest, gtp_type=16)
Expand All @@ -903,7 +919,10 @@ class GTPmorethan1500(Packet):
bind_layers(GTPHeader, GTP_PDCP_PDU_ExtensionHeader, next_ex=192, E=1)

# Bind GTP-U
bind_layers(UDP, GTP_U_Header, dport=2152)
bind_layers(UDP, GTP_U_Header, sport=2152)
bind_bottom_up(UDP, GTP_U_Header, dport=2152)
bind_bottom_up(UDP, GTP_U_Header, sport=2152)
bind_layers(UDP, GTP_U_Header, dport=2152, sport=2152)
bind_layers(GTP_U_Header, GTPErrorIndication, gtp_type=26, S=1)
bind_layers(GTP_U_Header, IP, gtp_type=255)
bind_top_down(GTP_U_Header, IP, gtp_type=255)
bind_top_down(GTP_U_Header, IPv6, gtp_type=255)
bind_top_down(GTP_U_Header, PPP, gtp_type=255)
15 changes: 15 additions & 0 deletions scapy/contrib/gtp.uts
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,21 @@ assert a.E == a.S == a.PN == 0
a = GTPHeader(raw(GTP_U_Header()/GTPErrorIndication()))
assert isinstance(a, GTP_U_Header)

= GTP_U_Header sub layers

a = IPv6(raw(IPv6()/UDP()/GTP_U_Header()/IPv6()))
b = IPv6(raw(IPv6()/UDP()/GTP_U_Header()/IP()))
c = IP(raw(IP()/UDP()/GTP_U_Header()/IPv6()))
d = IP(raw(IP()/UDP()/GTP_U_Header()/IP()))

assert isinstance(a[GTP_U_Header].payload, IPv6)
assert isinstance(b[GTP_U_Header].payload, IP)
assert isinstance(c[GTP_U_Header].payload, IPv6)
assert isinstance(d[GTP_U_Header].payload, IP)

a = IP(raw(IP()/UDP()/GTP_U_Header()/PPP()))
assert isinstance(a[GTP_U_Header].payload, PPP)

= GTPCreatePDPContextRequest(), basic instantiation
gtp = IP(src="127.0.0.1")/UDP(dport=2123)/GTPHeader(teid=2807)/GTPCreatePDPContextRequest()
gtp.dport == 2123 and gtp.teid == 2807 and len(gtp.IE_list) == 5
Expand Down