gopenfusion/tools/genstructs.py

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#!/bin/python
'''
genstructs.py - gopenfusion
Takes raw structures from a decompiled 'Assembly - CSharp.dll' from a main.unity3d fusionfall beta client,
and transpiles them to gopenfusion's custom packet structure & tags. Some useful constants are also grabbed
and transpiled. This requires a C compiler installed, since struct field padding is grabbed via the `offsetof()`
C macro. Some manual rearranging of structures from the disassembled source might be needed, however the script
should 'just werk' off of ilspycmd output. This script can also be modified to generate c-style structures
(because it already does!)
usage: ./genstructs.py [IN.cs] > structs.go
It's recommended to run structs.go through `gofmt`.
'''
from distutils.ccompiler import new_compiler
import subprocess
import sys
import os
PACK_ALIGN = 4
def sanitizeName(name: str) -> str:
# all exported fields in go must start capitalized
return name[0:1].upper() + name[1:]
def writeToFile(source: str, filePath: str) -> None:
with open(filePath, "w") as out:
out.write(source)
WARN_INVALID = False
class StructTranspiler:
class StructField:
def __init__(self, name: str, type: str, marshal: str) -> None:
self.marshal = marshal
self.type = type
self.ctype = type # for transpilation to c
self.tags = ""
self.size = 0
self.padding = 0
self.name = sanitizeName(name)
self.cname = self.name
self.needsPatching = False
if type == "byte":
self.type = "uint8"
self.ctype = "char"
self.size = 1
elif type == "sbyte":
self.type = "int8"
self.ctype = "char"
self.size = 1
elif type == "short":
self.type = "int16"
self.ctype = "short"
self.size = 2
elif type == "int":
self.type = "int32"
self.ctype = "int"
self.size = 4
elif type == "uint":
self.type = "uint32"
self.ctype = "int"
self.size = 4
elif type == "float":
self.type = "float32"
self.ctype = "float"
self.size = 4
elif type == "long":
self.type = "int64"
self.ctype = "long"
self.size = 8
elif type == "ulong":
self.type = "uint64"
self.ctype = "long"
self.size = 8
elif type == "byte[]":
self.size = int(marshal[(marshal.find("SizeConst = ") + len("SizeConst = ")):marshal.find(")]")])
self.type = "[%d]byte" % self.size
self.ctype = "char"
self.cname += "[%d]" % self.size
elif type == "short[]":
self.size = int(marshal[(marshal.find("SizeConst = ") + len("SizeConst = ")):marshal.find(")]")])
self.type = "[%d]int16" % self.size
self.ctype = "short"
self.cname += "[%d]" % self.size
self.size *= 2
elif type == "string":
# all strings in fusionfall are utf16, in a uint16 array
self.size = int(marshal[(marshal.find("SizeConst = ") + len("SizeConst = ")):marshal.find(")]")])
self.type = "string"
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self.addTag("size:\"%d\"" % self.size) # special tag to tell our decoder/encoder the size of the uint16[] array
self.ctype = "short"
self.cname += "[%d]" % self.size
self.size *= 2
elif type == "int[]":
self.size = int(marshal[(marshal.find("SizeConst = ") + len("SizeConst = ")):marshal.find(")]")])
self.type = "[%d]int32" % self.size
self.ctype = "int"
self.cname += "[%d]" % self.size
self.size *= 4
elif type == "float[]":
self.size = int(marshal[(marshal.find("SizeConst = ") + len("SizeConst = ")):marshal.find(")]")])
self.type = "[%d]float32" % self.size
self.ctype = "float"
self.cname += "[%d]" % self.size
self.size *= 4
elif type == "long[]":
self.size = int(marshal[(marshal.find("SizeConst = ") + len("SizeConst = ")):marshal.find(")]")])
self.type = "[%d]int64" % self.size
self.ctype = "long"
self.cname += "[%d]" % self.size
self.size *= 8
else:
# assume it's a structure that will be defined later
if type.find("[]") != -1: # it's an array!
type = type.replace("[]", "")
self.size = int(marshal[(marshal.find("SizeConst = ") + len("SizeConst = ")):marshal.find(")]")])
self.cname = self.name + "[%d]" % self.size
else:
self.cname = self.name
self.size = 1
self.type = sanitizeName(type)
self.ctype = sanitizeName(type)
self.needsPatching = True
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def addTag(self, tag: str) -> None:
if len(self.tags) > 0: # if there's already a tag defined, make sure there's a space separating them
self.tags += " "
self.tags += tag
def __init__(self, lines: list[str]) -> None:
self.name = "UnknownStruct"
self.size = 0
self.fields: list[self.StructField] = []
self.lines = lines
self.cursor = 0
def getLine(self) -> str:
return self.lines[self.cursor]
def getNextLine(self) -> str:
self.cursor += 1
return self.getLine()
def needsPatching(self) -> int:
for i in range(len(self.fields)):
if self.fields[i].needsPatching:
return i
return -1
# skip lines until we run into a '[StructLayout('
def searchStructLayout(self) -> None:
line = self.getLine()
while True:
if line.find("[StructLayout(") != -1 and line.find("Size = ") != -1:
self.size = int(line[(line.find("Size = ") + len("Size = ")):line.find(")]")])
line = self.getNextLine()
self.name = sanitizeName(line[(line.find("public struct ") + len("public struct ")):len(line)-1])
self.getNextLine()
return
line = self.getNextLine()
# skip lines until we find a struct field
def searchMarshal(self) -> StructField:
line = self.getLine()
while line.find("}") == -1:
if line.find("[MarshalAs(") != -1:
marshal = line
line = self.getNextLine()
typeStart = line.find("public ") + len("public ")
typeEnd = line.find(" ", typeStart)
type = line[typeStart:typeEnd]
name = line[typeEnd+1:line.find(";", typeEnd)]
return self.StructField(name, type, marshal)
line = self.getNextLine()
return None
def toCStyle(self) -> str:
source = "typedef struct {\n"
for field in self.fields:
source += "\t%s %s;\n" % (field.ctype, field.cname)
source += "} %s;\n" % self.name
for field in self.fields:
source += "printf(\"%d \""
source += ", offsetof(%s, %s));\n" % (self.name, field.name)
source += "printf(\"\\n\");\n"
return source
def populatePadding(self, offsets: list[str]) -> None:
currentSize = 0
for i in range(len(self.fields)):
currentSize += self.fields[i].size
if i < len(self.fields)-1 and currentSize != int(offsets[i+1]):
self.fields[i].padding = int(offsets[i+1]) - currentSize
currentSize += self.fields[i].padding
if currentSize < self.size:
self.fields[len(self.fields)-1].padding = self.size - currentSize
def parseStructure(self) -> None:
self.searchStructLayout()
line = self.getLine()
while line.find("}") == -1:
field = self.searchMarshal()
if field != None:
self.fields.append(field)
line = self.getLine()
def toGoStyle(self) -> str:
global WARN_INVALID
source = "type " + self.name + " struct {"
currentSize = 0
for field in self.fields:
currentSize += field.size
if field.padding > 0:
currentSize += field.padding
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field.addTag("pad:\"%d\"" % field.padding)
source += "\n\t" + field.name + " " + field.type
if len(field.tags) > 0:
source += " `" + field.tags + "`"
if currentSize != self.size:
source += "\n// WARNING: computed size is %d, needs to be %d!!" % (currentSize, self.size)
WARN_INVALID = True
else:
source += "\n// SIZE: %d" % self.size
source += "\n}\n"
return source
def transpileStructs(lines: list[str]) -> list[StructTranspiler]:
structs: list[StructTranspiler] = []
def tryPatching(struct: StructTranspiler) -> StructTranspiler:
f = struct.needsPatching()
lastf = None
while f != -1 and lastf != f:
# search for existing struct
name = struct.fields[f].type
for s in structs:
if s.name == name:
if struct.fields[f].size > 1: # was it an array?
struct.fields[f].type = ("[%d]" % struct.fields[f].size) + struct.fields[f].type
struct.fields[f].size *= s.size # field's size was set to 1 even if it wasn't an array
struct.fields[f].needsPatching = False # mark done
break
lastf = f
f = struct.needsPatching()
return struct
while True:
try:
struct = StructTranspiler(lines)
struct.parseStructure()
# try to resolve patches right here
struct = tryPatching(struct)
structs.append(struct)
lines = struct.lines[struct.cursor:]
except:
break
# move all structures that need patching to the end (so hopefully they'll be in the
# right order for our C source generation)
def sortStruct(s: StructTranspiler):
if s.needsPatching() != -1:
return 1
return 0
structs.sort(key=sortStruct)
# check for undefined types in structures and patch the sizes
for i in range(len(structs)):
structs[i] = tryPatching(structs[i])
# we compile a small c program to grab the exact offsets and alignments
source = "#include <stdio.h>\n#include <stddef.h>\n"
source += "int main() {\n"
source += "#pragma pack(push)\n#pragma pack(%d)\n" % PACK_ALIGN
for struct in structs:
source += struct.toCStyle()
source += "#pragma pack(pop)\nreturn 0;\n}\n"
writeToFile(source, "tmp.c")
compiler = new_compiler()
compiler.compile(['tmp.c'])
compiler.link_executable(['tmp.o'], 'tmp')
# patch padding bytes
lines = subprocess.getoutput(['./tmp']).splitlines()
for i in range(len(structs)):
structs[i].populatePadding(lines[i].split(" "))
return structs
class ConstTranspiler:
def __init__(self, lines: list[str]) -> None:
self.lines = lines
self.cursor = 0
self.value = 0
self.name = 0
def getLine(self) -> str:
return self.lines[self.cursor]
def getNextLine(self) -> str:
self.cursor += 1
return self.getLine()
# skip lines until we run into a 'public const uint '
def searchForConst(self) -> None:
line = self.getLine()
while True:
if line.find("public const uint ") != -1:
nameStart = (line.find("public const uint ") + len("public const uint "))
self.value = int(line[(line.find("= ", nameStart) + len("= ")):line.find("u;")])
self.name = line[nameStart:line.find(" = ", nameStart)]
self.getNextLine()
return
line = self.getNextLine()
def transpileConsts(lines: list[str]) -> list[ConstTranspiler]:
consts: list[ConstTranspiler] = []
while True:
try:
const = ConstTranspiler(lines)
const.searchForConst()
consts.append(const)
lines = const.lines[const.cursor:]
except:
break
return consts
if __name__ == '__main__':
inFilePath = sys.argv[1]
iFile = open(inFilePath, "r")
lines = iFile.readlines()
structs = transpileStructs(lines)
consts = transpileConsts(lines)
# emit structures
source = "// generated via genstructs.py"
if WARN_INVALID:
source += " - WARN!! Not all structures are valid, grep 'WARNING'\n"
else:
source += " - All structure padding and member alignment verified\n"
source += "package protocol\n\nconst (\n"
for const in consts:
source += "\t%s = 0x%x\n" % (const.name, const.value)
source += ")\n\n"
for struct in structs:
source += struct.toGoStyle() + "\n"
print(source)
os.remove("tmp")
os.remove("tmp.c")
os.remove("tmp.o")