ToorChat/vstruct/__init__.py

287 lines
8.2 KiB
Python

import struct
from StringIO import StringIO
import vstruct.primitives as vs_prims
def isVstructType(x):
return isinstance(x, vs_prims.v_base)
class VStruct(vs_prims.v_base):
def __init__(self, bigend=False):
# A tiny bit of evil...
object.__setattr__(self, "_vs_values", {})
vs_prims.v_base.__init__(self)
self._vs_name = self.__class__.__name__
self._vs_fields = []
self._vs_field_align = False # To toggle visual studio style packing
self._vs_padnum = 0
self._vs_fmtbase = '<'
if bigend:
self._vs_fmtbase = '>'
def vsGetClassPath(self):
'''
Return the entire class name (including module path).
'''
return '%s.%s' % (self.__module__, self._vs_name)
def vsParse(self, bytes, offset=0):
"""
For all the primitives contained within, allow them
an opportunity to parse the given data and return the
total offset...
"""
plist = self.vsGetPrims()
fmt = self.vsGetFormat()
size = struct.calcsize(fmt)
vals = struct.unpack(fmt, bytes[offset:offset+size])
for i in range(len(plist)):
plist[i].vsSetParsedValue(vals[i])
def vsEmit(self):
"""
Get back the byte sequence associated with this structure.
"""
fmt = self.vsGetFormat()
r = []
for p in self.vsGetPrims():
r.append(p.vsGetFmtValue())
return struct.pack(fmt, *r)
def vsGetFormat(self):
"""
Return the format specifier which would then be used
"""
# Unpack everything little endian, let vsParseValue deal...
ret = self._vs_fmtbase
for p in self.vsGetPrims():
ret += p.vsGetFormat()
return ret
def vsIsPrim(self):
return False
def vsGetFields(self):
ret = []
for fname in self._vs_fields:
fobj = self._vs_values.get(fname)
ret.append((fname,fobj))
return ret
def vsGetField(self, name):
x = self._vs_values.get(name)
if x == None:
raise Exception("Invalid field: %s" % name)
return x
def vsHasField(self, name):
return self._vs_values.get(name) != None
def vsSetField(self, name, value):
if isVstructType(value):
self._vs_values[name] = value
return
x = self._vs_values.get(name)
return x.vsSetValue(value)
# FIXME implement more arithmetic for structs...
def __ixor__(self, other):
for name,value in other._vs_values.items():
self._vs_values[name] ^= value
return self
def vsAddField(self, name, value):
if not isVstructType(value):
raise Exception("Added fields MUST be vstruct types!")
# Do optional field alignment...
if self._vs_field_align:
# If it's a primitive, all is well, if not, pad to size of
# the first element of the VStruct/VArray...
if value.vsIsPrim():
align = len(value)
else:
fname = value._vs_fields[0]
align = len(value._vs_values.get(fname))
delta = len(self) % align
if delta != 0:
print "PADDING %s by %d" % (name,align-delta)
pname = "_pad%d" % self._vs_padnum
self._vs_padnum += 1
self._vs_fields.append(pname)
self._vs_values[pname] = vs_prims.v_bytes(align-delta)
self._vs_fields.append(name)
self._vs_values[name] = value
def vsGetPrims(self):
"""
return an order'd list of the primitive fields in this
structure definition. This is recursive and will return
the sub fields of all nested structures.
"""
ret = []
for name, field in self.vsGetFields():
if field.vsIsPrim():
ret.append(field)
else:
ret.extend(field.vsGetPrims())
return ret
def vsGetTypeName(self):
return self._vs_name
def vsGetOffset(self, name):
"""
Return the offset of a member.
"""
offset = 0
for fname in self._vs_fields:
if name == fname:
return offset
x = self._vs_values.get(fname)
offset += len(x)
raise Exception("Invalid Field Specified!")
def vsGetPrintInfo(self, offset=0, indent=0, top=True):
ret = []
if top:
ret.append((offset, indent, self._vs_name, self))
indent += 1
for fname in self._vs_fields:
x = self._vs_values.get(fname)
off = offset + self.vsGetOffset(fname)
if isinstance(x, VStruct):
ret.append((off, indent, fname, x))
ret.extend(x.vsGetPrintInfo(offset=off, indent=indent, top=False))
else:
ret.append((off, indent, fname, x))
return ret
def __len__(self):
fmt = self.vsGetFormat()
return struct.calcsize(fmt)
def __getattr__(self, name):
# Gotta do this for pickle issues...
vsvals = self.__dict__.get("_vs_values")
if vsvals == None:
vsvals = {}
self.__dict__["_vs_values"] = vsvals
r = vsvals.get(name)
if r is None:
raise AttributeError(name)
if isinstance(r, vs_prims.v_prim):
return r.vsGetValue()
return r
def __setattr__(self, name, value):
# If we have this field, asign to it
x = self._vs_values.get(name, None)
if x != None:
return self.vsSetField(name, value)
# If it's a vstruct type, create a new field
if isVstructType(value):
return self.vsAddField(name, value)
# Fail over to standard object attribute behavior
return object.__setattr__(self, name, value)
def __iter__(self):
# Our iteration returns name,field pairs
ret = []
for name in self._vs_fields:
ret.append((name, self._vs_values.get(name)))
return iter(ret)
def __repr__(self):
return self._vs_name
def tree(self, va=0, reprmax=None):
ret = ""
for off, indent, name, field in self.vsGetPrintInfo():
rstr = field.vsGetTypeName()
if isinstance(field, vs_prims.v_number):
val = field.vsGetValue()
rstr = '0x%.8x (%d)' % (val,val)
elif isinstance(field, vs_prims.v_prim):
rstr = repr(field)
if reprmax != None and len(rstr) > reprmax:
rstr = rstr[:reprmax] + '...'
ret += "%.8x (%.2d)%s %s: %s\n" % (va+off, len(field), " "*(indent*2),name,rstr)
return ret
class VArray(VStruct):
def __init__(self, elems=()):
VStruct.__init__(self)
for e in elems:
self.vsAddElement(e)
def vsAddElement(self, elem):
"""
Used to add elements to an array
"""
idx = len(self._vs_fields)
self.vsAddField("%d" % idx, elem)
def __getitem__(self, index):
return self.vsGetField("%d" % index)
#FIXME slice asignment
def resolve(impmod, nameparts):
"""
Resolve the given (potentially nested) object
from within a module.
"""
if not nameparts:
return None
m = impmod
for nname in nameparts:
m = getattr(m, nname, None)
if m == None:
break
return m
# NOTE: Gotta import this *after* VStruct/VSArray defined
import vstruct.defs as vs_defs
def getStructure(sname):
"""
Return an instance of the specified structure. The
structure name may be a definition that was added with
addStructure() or a python path (ie. win32.TEB) of a
definition from within vstruct.defs.
"""
x = resolve(vs_defs, sname.split("."))
if x != None:
return x()
return None
def getModuleNames():
return [x for x in dir(vs_defs) if not x.startswith("__")]
def getStructNames(modname):
ret = []
mod = resolve(vs_defs, modname)
if mod == None:
return ret
for n in dir(mod):
x = getattr(mod, n)
if issubclass(x, VStruct):
ret.append(n)
return ret