我是网络安全的学生，我正在尝试使用Scapy的OLSR支持，但当然这个版本已经过时，所以我正在尝试修复但是在Python上成为新手我希望你能帮助我
目标是创建OLSR数据包以充当网络节点。
以下是我在做了一些改动之后从Scapy得到的代码你相信我必须做的工作是post_build方法。
#!/usr/bin/env python
#############################################################################
## ##
## olsr.py --- OLSR protocol support for Scapy ##
## ##
## Copyright (C) 2005 EADS/CRC security team <dcrstic.ccr(at)eads.net> ##
## Arnaud Ebalard <arnaud.ebalard@eads.net> ##
## ##
## This program is free software; you can redistribute it and/or modify it ##
## under the terms of the GNU General Public License version 2 as ##
## published by the Free Software Foundation; version 2. ##
## ##
## 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. ##
## ##
#############################################################################
#
# $Log: olsr.py,v $
# Revision 1.15 2006/02/08 13:22:52 ebalard
# Suppressed old comments.
#
# Revision 1.14 2006/02/08 13:14:51 ebalard
# Final Version. Evverything is up and running in v4/v6. Let's wait for bugs.
#
# Revision 1.13 2006/02/06 19:16:59 ebalard
# NetListField is now up and running, allowing user to pass hna list in
# many different ways.
#
# Revision 1.12 2006/02/06 15:41:35 ebalard
# _OLSROrigAddrField() is now ready.
#
# Revision 1.11 2006/02/03 15:19:29 ebalard
# In fact, _OLSROrigAddrField() is buggy due to _underlayer and Scapy
# internal games. bug correction is in progress.
#
# Revision 1.10 2006/02/03 12:14:41 ebalard
# _OLSROrigAddrField now supports v4 and v6 addresses depending on network
# protocols used. Simple tests performed. Require some more.
#
# Revision 1.9 2006/01/27 16:05:18 ebalard
# conf.olsr_IPv6available is now set if scapy6 has been loaded (else its
# value is 0).
#
# Revision 1.8 2006/01/27 15:11:16 ebalard
# Bug in _OLSRTimeField corrected.
# Added scapy6 loading if available (will be used for IPv6 version).
#
# Revision 1.7 2006/01/27 12:57:23 ebalard
# post_dissect() method is _now_ really ok.
#
# Revision 1.6 2006/01/27 10:04:00 ebalard
# Bug in do_dissect() corrected.
#
# Revision 1.5 2006/01/27 08:53:37 ebalard
# NetListField is now working fine.
#
# Revision 1.4 2006/01/26 18:41:29 ebalard
# Almost Everything is there. Need polish, debug, more tests and solving
# problems referenced in TODO marks.
#
# Revision 1.3 2006/01/25 18:30:51 ebalard
# Banner typo corrected.
#
# Revision 1.2 2006/01/25 18:29:14 ebalard
# All main classes are defined.
#
# Revision 1.1.1.1 2006/01/25 09:41:53 ebalard
# Creation of scapy-olsr repository.
# TODO List :
# - create overloaded_fields for classes that need them. For example
# in order to set destination IP adresses (v4 and also v6)
# - Deal with the sequence number fields that should be incremented
# automatically (sn, msgsn, ansn)
# - Everytime there is an originator address, we should use by default
# the address provided by conf.iface. See if we can directly use
# and IPSourceField.
# - Same for TC messages with addresses available on the system, other
# than that of conf.iface ?
# - See if 'anma' field in TC message needs a different default value to
# basically include at least 1 IP
# - At the end of the file is an awful hack : we give UDP source port
# a value different from 53 because Scapy would dissect such a packet
# as DNS traffic. Let call that an unwanted feature of scapy ;-)
# - see with Phil to make this field available in Scapy. It has
# disappeared somewhere in some version.
# - See "IPv6 for OLSR" to make it generic (v4/v6) and deal with v6
# traffic if Scapy IPv6 extensions are available.
# Basic cases :
#
# IP()/UDP()/OLSR()/OLSR_MID()
# IP()/UDP()/OLSR()/OLSR_HELLO()/OLSR_HELLO_LinkMessage()/OLSR_HELLO_LinkMessage()/OLSR_HELLO_LinkMessage
# IP()/UDP()/OLSR()/OLSR_TC()
# IP()/UDP()/OLSR()/OLSR_HNA()
import math
try:
# Try to get IPv6 support
from scapy6.all import *
conf.olsr_IPv6available=1
except:
from scapy.all import *
conf.olsr_IPv6available=0
# Emission interval constants : section 18.2 of RFC 3626
# Most of them are unused in Scapy, at the moment
conf.olsr_HELLO_INTERVAL=2
conf.olsr_REFRESH_INTERVAL=2
conf.olsr_TC_INTERVAL=5
conf.olsr_MID_INTERVAL=conf.olsr_TC_INTERVAL
conf.olsr_HNA_INTERVAL=conf.olsr_TC_INTERVAL
# Holding time constants : section 18.3 of RFC 3626
# Most of them are unused in Scapy, at the moment
conf.olsr_NEIGHB_HOLD_TIME=3*conf.olsr_REFRESH_INTERVAL
conf.olsr_TOP_HOLD_TIME=3*conf.olsr_TC_INTERVAL
conf.olsr_DUP_HOLD_TIME=30
conf.olsr_MID_HOLD_TIME=3*conf.olsr_MID_INTERVAL
conf.olsr_HNA_HOLD_TIME=3*conf.olsr_HNA_INTERVAL
# The proposed value of constant C in sect. 18.1 of RFC 3626 is 1/16
conf.olsr_C = 1.0/16
# Referenced in Section 18.4 of RFC 3626
olsr_types = { 1: "OLSR HELLO Message",
2: "OLSR TC Message",
3: "OLSR MID Message",
4: "OLSR HNA Message" }
# Provides a mapping between previous types and associated Scapy
# classes
olsr_cls = { 1: "OLSR_HELLO",
2: "OLSR_TC",
3: "OLSR_MID",
4: "OLSR_HNA" }
# Referenced in Section 18.5 of RFC 3626. Used by _OLSRLinkField
olsr_link_types = { 0: "UNSPEC_LINK",
1: "ASYM_LINK",
2: "SYM_LINK",
3: "LOST_LINK" }
# Referenced in Section 18.6 of RFC 3626. Used by _OLSRLinkField
olsr_neighbor_types = { 0: "NOT_NEIGH",
1: "SYM_NEIGH",
2: "MPR_NEIGH",
3: "Unknown (not defined by RFC 3626)" }
# Referenced in Section 18.7 of RFC 3626
olsr_link_hysteresis = { 0.8: "HYST_THRESHOLD_HIGH",
0.3: "HYST_THRESHOLD_LOW",
0.5: "HYST_SCALING" }
# Referenced in Section 18.8 of RFC 3626
olsr_willingness = { 0: "WILL_NEVER",
1: "WILL_LOW",
3: "WILL_DEFAULT",
6: "WILL_HIGH",
7: "WILL_ALWAYS"}
# This class provides OLSR Message classes (TC, MID, HNA, but not HELLO)
# with a guess_payload_class() method that performs early guessing of
# following message type and returns associated class that should be
# used for dissection.
class _OLSRDefaultPayload(Packet):
name = "Provides OLSR Message classes with default_payload_class() method"
fields_desc = []
def default_payload_class(self, p):
# OLSR Message classes are at least 12 bytes long
if len(p) >= 12:
return globals().get(olsr_cls.get(ord(p[0]),"Raw"), "Raw")
return Raw
# Main OLSR header, used to provide length and serial for specific
# stacked messages (HELLO, TC, MID and HNA)
class OLSR(_OLSRDefaultPayload):
name = "OLSR Header"
fields_desc = [ ShortField("len", None),
ShortField("sn", 0) ]
def post_build(self, pkt, p):
# Packet Length Computation
if self.len is None:
l = len(p)
pkt = struct.pack("!H", l) + pkt[2:]
#pkt = pkt[:1] + hex(l)[2:]+ pkt[2:]
return pkt+p
class IPListField(StrLenField):
islist = 1
def getfield(self, pkt, s):
# grab announced length
l = getattr(pkt, self.fld)
f = pkt.get_field(self.fld)
if isinstance(f, FieldLenField):
l += f.shift
# Are we carried by IPv4 or IPv6 ? -> set self.af and self.addrlen
under = pkt.underlayer
while under is not None:
if conf.olsr_IPv6available and isinstance(under, IPv6):
self.af =socket.AF_INET6
self.addrlen = 16
break
elif isinstance(under, IP):
self.af = socket.AF_INET
self.addrlen = 4
break
under = under.underlayer
if under is None:
warning("No IP or IPv6 underlayer to select OLSR carried")
warning("address type. Using IPv6 as fallback.")
return s[l:], self.m2i(pkt,s[:l])
def addfield(self, pkt, s, val):
return s+self.i2m(pkt,val)
def any2i(self, pkt, x):
if type(x) is list:
return map(lambda z,pkt=pkt:self.any2i_one(pkt,z), x)
else:
r = []
r.append(self.any2i_one(pkt,x))
return r
def any2i_one(self, pkt, x):
if x is None or x is "":
return None
if x.count(':') > 0: # IPv6
self.af =socket.AF_INET6
self.addrlen = 16
return x
else: # IPv4
self.af =socket.AF_INET
self.addrlen = 4
return x
def m2i(self, pkt, x):
r = []
l = self.addrlen # has been set by getfield (I hope so)
while len(x) >= l:
r.append(socket.inet_ntop(self.af, x[:l]))
x = x[l:]
return r
def i2m(self, pkt, x):
s = ""
if len(x) > 0:
for ip in x:
s += socket.inet_pton(self.af, ip)
return s
return ""
def i2repr(self, pkt, x):
s = []
if x == None:
return "[]"
for y in x:
s.append('%s' % y)
return "[ %s ]" % (", ".join(s))
# This OLSR Time field is used for VTime and HTime (respectively in
# Message headers and Hello messages). Decription is provided in
# section 18.3 of RFC 3626. Defaut value of C is the one found in
# conf.olsr_C (default to 1/16).
#
# TODO : check if 'from scratch' formulas give same results as that
# provided in section 18.3 of RFC 3626
class _OLSRTimeField(ByteField):
def m2i(self, pkt, x):
a = ((int(x)>>4) & 0x0f)
b = int(x) & 0x0f
C = conf.olsr_C
return C*(1+float(a)/16)*(2**b)
def i2m(self, pkt, x):
C = conf.olsr_C
tmp = float(x)/C
# base arg is available from python 2.3
b = int(math.log(tmp, 2))
a = int((float(tmp)/(2**b) - 1)*16)
# TODO : perform some tests on computed value.
return a*16+b
def i2repr(self, pkt, x):
x=int(x)
a = ((x>>4) & 0x0f)
b = x & 0x0f
C = conf.olsr_C
return "%d sec (with C=%.4f, a is %d and b is %d)" % (x, C, a, b)
# Hack :to avoid errors in following class when IPv6 extensions are not
# available.
if not conf.olsr_IPv6available:
class IP6Field: pass
# How do we know the AF for input parameters :
# - in getfield() : we access underlayer till we find an IP or IPv6 layer.
# - in h2i() : we try to find ':' in input parameter to see if it's an IPv6 @.
class _OLSROrigAddrField(IPField, IP6Field):
# In getfield(), we will get AF based on kind of IP layer carrying
# the packet
def getfield(self, pkt, s):
under = pkt.underlayer
while under is not None:
if conf.olsr_IPv6available and isinstance(under, IPv6):
self.sz = 16
self.fmt = "16s"
break
elif isinstance(under, IP):
self.sz = 4
self.fmt = "4s"
break
under = under.underlayer
if under is None:
warning("No IP or IPv6 underlayer to select OLSR carried address type. Using IPv6 as fallback.")
return s[self.sz:], self.m2i(pkt,s[:self.sz])
def addfield(self, pkt, s, val):
return s+self.i2m(pkt,val)
# In h2i(), the only way to get AF is by parsing given address string
# looking for ':'
def h2i(self, pkt, x):
if (conf.olsr_IPv6available and
((type(x) is str and x.count(':') > 0)
or (type(x) is list and len(x) > 0 and x[0].count(':') > 0))):
self.fmt="16s"
self.sz=16
return IP6Field.h2i(self, pkt, x)
else:
self.fmt="4s"
self.sz=4
return IPField.h2i(self, pkt, x)
def m2i(self, pkt, x):
if conf.olsr_IPv6available and self.sz == 16:
return IP6Field.m2i(self, pkt, x)
else:
return IPField.m2i(self, pkt, x)
def i2m(self, pkt, x):
# Deal with default value if user does not provide one
if x is None:
if conf.iface is not None:
if conf.olsr_IPv6available:
warning("No address provided. IPv6 extensions being available, IPv6 global address")
warning("of %s interface will be used." % conf.iface)
x=get_if_addr6(conf.iface)
self.sz=16
self.fmt="16s"
if x is None:
warning("%s has no IPv6 address. Using :: as fallback." % conf.iface)
x="::"
else:
warning("No address provided. IPv4 address of %s interface will be used." % conf.iface)
x=get_if_addr(conf.iface)
self.sz=4
self.fmt="4s"
if x is None:
warning("%s has no IPv4 address. Using 0.0.0.0 as fallback." % conf.iface)
x="0.0.0.0"
# Call IPv4/v6 specific method
if self.sz == 16: # implies conf.IPv6available
return IP6Field.i2m(self, pkt, x)
else:
return IPField.i2m(self, pkt, x)
#### OLSR MID Message class : section 5.1 of RFC 3626
class OLSR_MID(_OLSRDefaultPayload, Packet):
name = "OLSR MID Message"
fields_desc = [ ByteEnumField("type", 3, olsr_types ),
_OLSRTimeField("vtime", conf.olsr_MID_HOLD_TIME ),
FieldLenField("msgsize", None , "interfaces", "!H", adjust=lambda pkt,x:x-12),
_OLSROrigAddrField("oaddr", None),
ByteField("ttl", 255), # RFC 3626 sect 5.1
ByteField("hopcount", 0 ),
ShortField("msgsn", 0),
IPListField("interfaces", [], "msgsize") ]
# This class performs specific processing for "Link Code" fields found
# in Hello Link Messages. Described in section 6.1.1 of RFC 3626.
class _OLSRLinkField(ByteField):
def any2i(self, pkt, x):
return x
def i2repr(self, pkt, x):
# RFC 3626 only specifies processing of Link Codes < 16
if x < 16:
ntype= olsr_neighbor_types[(x & 0x0c)>>2]
ltype= olsr_link_types[(x & 0x03)]
res = "%d (Neighbor type:%s, Link type:%s)" % (x, ntype, ltype)
else:
res = "%d (not < 16, i.e. not RFC 3626 compliant)" % x
return res
#TODO : what about writing any2i ?
# This messages are intended to be stacked behind OLSR_HELLO messages
class OLSR_HELLO_LinkMessage(Packet):
name = "OLSR HELLO - Link Message"
fields_desc = [ _OLSRLinkField("linkcode", 0x06), # SYM_NEIGH and SYM_LINK
ByteField("res", 0),
FieldLenField("size", None, "neighint", "!H", adjust=lambda pkt,x:x-4),
IPListField("neighint", [], "size") ]
# TODO : find a better wayt to have same level of indentation for
# link message packet
def show(self, indent=3, lvl=0):
ct = conf.color_theme
print "%s %s %s" % (ct.punct("###["),
ct.layer_name(self.name),
ct.punct("]###"))
for f in self.fields_desc:
if isinstance(f, Emph):
ncol = ct.emph_field_name
vcol = ct.emph_field_value
else:
ncol = ct.field_name
vcol = ct.field_value
print " %s%-10s%s %s" % (" "*indent*lvl,
ncol(f.name),
ct.punct("="),
vcol(f.i2repr(self,self.__getattr__(f))))
dec = 1
if isinstance(self.payload, OLSR_HELLO_LinkMessage):
dec = 0
self.payload.display(indent=indent,lvl=lvl+dec)
# OLSR Hello Header : on this packet, multiple OLSR Link Messages can
# be stacked.
class OLSR_HELLO(Packet):
name = "OLSR HELLO Message"
fields_desc = [ ByteEnumField("type", 1, olsr_types),
ByteField("vtime", conf.olsr_NEIGHB_HOLD_TIME),
ShortField("msgsize", None),
_OLSROrigAddrField("oaddr", None),
ByteField("ttl", 1), #RFC 3626 sect 6.1
ByteField("hopcount", 0 ),
ShortField("msgsn", 0),
XShortField("res", 0),
_OLSRTimeField("htime", conf.olsr_HELLO_INTERVAL),
ByteEnumField("willingness", 3, olsr_willingness) ]
def do_dissect(self, s):
# Dissecting fields of OLSR_HELLO packet
flist = self.fields_desc[:]
flist.reverse()
while s and flist:
f = flist.pop()
s,fval = f.getfield(self, s)
self.fields[f] = fval
# post_dissect() call has been removed. Make no sense here.
# extract_padding() call has been removed. Make no sense here.
# l will be the length of following link messages train (beginning)
# what follows beginning (end) is another OLSR message
l = self.msgsize - 16
print hexdump(s[:1])
print hexdump(s[1:])
beginning,end = s[:1], s[1:]
self.do_dissect_payload(beginning)
# beginning has been dissected has a chain of Link messages.
# Let's gain the end of that train
while isinstance(self.payload, OLSR_HELLO_LinkMessage):
self = self.payload
# If end can be parsed has an OLSR Message Header, let's find
# its type, instantiate it and add the result to our packet
if len(end) >= 12:
cls = globals().get(olsr_cls.get(ord(end[0]),"Raw"), "Raw")
self.add_payload(cls(end))
def post_build(self, pkt, p):
# compute length till payload is end of Link Message classes
if self.msgsize is None:
while isinstance(self.payload, OLSR_HELLO_LinkMessage):
self = self.payload
self=self.payload
l = len(pkt)
if self is not None:
l -= len(str(self))
pkt = pkt[:2]+struct.pack("!H", l)+pkt[4:]
return pkt+p
# Defined in section 9.1
class OLSR_TC(_OLSRDefaultPayload):
name = "OLSR Topology Control (TC) Message"
fields_desc = [ ByteEnumField("type", 2, olsr_types),
ByteField("vtime", conf.olsr_TOP_HOLD_TIME),
FieldLenField("msgsize", None, "anma", "!H", adjust=lambda pkt,x:x-16),
_OLSROrigAddrField("oaddr", None),
ByteField("ttl", 255), # RFC 3626 Sect 9.1
ByteField("hopcount", 0 ),
ShortField("msgsn", 0),
XShortField("ansn", 0),
XShortField("res", 0),
IPListField("anma", [], "msgsize") ]
# Internal representation of the NetListField is a list of tuple (net, mask).
# - net is in printable representation (output of inet_ntop)
# - mask is in printable representation (output of inet_ntop)
# Supports v4 and v6. See IPListField comment.
class NetListField(StrLenField):
islist = 1
def i2repr(self, pkt, x): # v4/v6 independent
s = []
if x is None:
return "[]"
for y in x:
net, mask = y
s.append('(%s, %s)' % (net, mask))
return "[ %s ]" % (", ".join(s))
def getfield(self, pkt, s):
# grab announced length
l = getattr(pkt, self.fld)
f = pkt.get_field(self.fld)
if isinstance(f, FieldLenField):
l += f.shift
# Are we carried by IPv4 or IPv6 ? -> set self.af and self.addrlen
under = pkt.underlayer
while under is not None:
if conf.olsr_IPv6available and isinstance(under, IPv6):
self.af =socket.AF_INET6
self.addrlen = 16
break
elif isinstance(under, IP):
self.af = socket.AF_INET
self.addrlen = 4
break
under = under.underlayer
if under is None:
warning("No IP or IPv6 underlayer to select OLSR carried")
warning("address type. Using IPv6 as fallback.")
return s[l:], self.m2i(pkt,s[:l])
def addfield(self, pkt, s, val):
return s+self.i2m(pkt,val)
def any2i(self, pkt, x):
if type(x) is list:
return map(lambda z,pkt=pkt:self.any2i_one(pkt,z), x)
else:
r = []
r.append(self.any2i_one(pkt,x))
return r
# TODO : reread this function and search the bugs
def any2i_one(self, pkt, x):
if x is None or x is "":
return None
if type(x) is str: # v4/v6 host/net (2001::/64 or 172.16.0.0/24)
if x.count(':') > 0: # IPv6
self.af =socket.AF_INET6
self.addrlen = 16
res=x.split("/")
l = len(res)
if l == 1: # host case. Prefix will be 128
return self.any2i_one("%s/%d", (res[0],128))
elif l == 2: # net case (most common case)
return (res[0], socket.inet_ntop(socket.AF_INET6, in6_cidr2mask(int(res[1]))))
else: # error
warning( "give me something better" )
return None
else: # v4 net or host : "172.16.0.0/24"
self.af =socket.AF_INET
self.addrlen = 4
res=x.split("/")
l = len(res)
if l == 1: # host case. Prefix will be 32
return (res[0], ltoa(itom(32)))
elif l == 2: # net case (most common case)
return (res[0], ltoa(itom(int(res[1]))))
else: # error
warning( "give me something better" )
return None
elif type(x) is tuple: # for thos loving tuples
if type(x[1]) is int:
return self.any2i_one(pkt, "%s/%d" % (x[0], x[1]))
else:
# tuple (Net, Mask) to be able to send corrupted values.
# Valid values are : ("2001::1", "ff:ff::"), ("172.16.0.0", "255.255.0.0")
return x
# Third case : error
else:
return None
def m2i(self, pkt, x):
r = []
l = self.addrlen
while len(x) >= 8:
r.append((socket.inet_ntop(self.af, x[:l]),
socket.inet_ntop(self.af, x[l:2*l])))
x = x[2*l:]
return r
def i2m(self, pkt, x):
s = ""
if len(x) > 0:
for net in x:
s += socket.inet_pton(self.af, net[0]) + socket.inet_pton(self.af, net[1])
return s
return ""
# Host and Network Association Message. Sect 12 of RFC 3626
#
# "In order to provide this capability of injecting external routing
# information into an OLSR MANET, a node with such non-MANET
# interfaces periodically issues a Host and Netwrok Association (HNA)
# message, containing sufficient information for the recipients to
# construct an appropriate routing table"
#
# TODO :
# - set Vtime and ttl
class OLSR_HNA(_OLSRDefaultPayload):
name = "OLSR Host and Network Association Message"
fields_desc = [ ByteEnumField("type", 4, olsr_types),
ByteField("vtime", conf.olsr_HNA_HOLD_TIME),
FieldLenField("msgsize", None, "anma", "!H", adjust=lambda pkt,x:x-16),
_OLSROrigAddrField("oaddr", None),
ByteField("ttl", 255), # RFC 3626 Sect. 12.1
ByteField("hopcount", 0 ),
ShortField("msgsn", 0),
NetListField("hna", [], "msgsize") ]
bind_layers( UDP, OLSR , { "sport":54, "dport":698 } )
bind_layers( OLSR_HELLO, OLSR_HELLO_LinkMessage, { })
bind_layers( OLSR_HELLO_LinkMessage, OLSR_HELLO_LinkMessage, { } )
interact(mydict=globals(),mybanner="OLSR add-ons $Revision: 1.15 $ 0.1")
规格：CentOS上的Python 2.6和Scapy 2.2.0。
修改：要为我的问题添加一些细节，希望得到答案，
当我使用 -
在Scapy上创建数据包时p = IP(tos=0xc0, id=0, flags=0x02,
dst='10.0.0.255')/UDP()/OLSR()/OLSR_HELLO(oaddr='10.0.0.1',
willingness=0)/OLSR_HELLO_LinkMessage()
已成功创建。问题是，当我发送它并通过Wireshark捕获它时，数据包的大小不符合协议要求，这并不意味着数据包格式错误，这意味着如果我尝试将其发送到守护程序，如OLSRD，它被拒绝了。
现在提供更多详细信息，当我执行p.show2()时，我可以看到UDP的长度是32，但是当我尝试通过Wireshark从OLSRD捕获数据包时，我看到UDP长度是28。
当然，在OLSRD和Scapy Packets的比较中，OLSR层是相同的，但是数据包的总长度是不同的。
如果您需要更多详细信息，请与我们联系。
PS：因为我是学生并不意味着我想要准备好代码，我正在努力理解并解决我的问题。提前谢谢。