mirror of https://github.com/ConsenSys/mythril
blockchainethereumsmart-contractssoliditysecurityprogram-analysissecurity-analysissymbolic-execution
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152 lines
3.0 KiB
152 lines
3.0 KiB
from ethereum import opcodes
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import codecs
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import re
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regex_PUSH = re.compile('^PUSH(\d*)$')
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def disassembly_to_easm(disassembly):
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easm = ""
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for instruction in disassembly:
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easm += instruction['opcode']
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if 'argument' in instruction:
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easm += " 0x" + codecs.decode(instruction['argument'], 'ascii')
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easm += "\n"
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return easm
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def easm_to_disassembly(easm):
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regex_CODELINE = re.compile('^([A-Z0-9]+)(?:\s+([0-9a-fA-Fx]+))?$')
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disassembly = []
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codelines = easm.split('\n')
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for line in codelines:
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m = re.search(regex_CODELINE, line)
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if not m:
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# Invalid code line
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continue
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instruction = {}
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instruction['opcode'] = m.group(1)
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if m.group(2):
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instruction['argument'] = m.group(2)[2:]
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disassembly.append(instruction)
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return disassembly
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def get_opcode_from_name(name):
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for opcode, value in opcodes.opcodes.items():
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if name == value[0]:
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return opcode
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raise RuntimeError("Unknown opcode")
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def find_opcode_sequence(pattern, disassembly):
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match_indexes = []
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pattern_length = len(pattern)
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for i in range(0, len(disassembly) - pattern_length):
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if disassembly[i]['opcode'] == pattern[0]:
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matched = True
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for j in range(1, len(pattern)):
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if not (disassembly[i + j]['opcode'] == pattern[j]):
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matched = False
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break
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if (matched):
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match_indexes.append(i)
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return match_indexes
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def resolve_functions(disassembly):
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function_stubs = find_opcode_sequence(['PUSH4', 'EQ', 'PUSH2', 'JUMPI'], disassembly)
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functions = []
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for index in function_stubs:
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func = {}
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func['hash'] = disassembly[index]['argument']
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func['address'] = disassembly[index + 2]['argument']
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functions.append(func)
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return functions
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def disassemble(bytecode):
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disassembly = []
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i = 0
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while i < len(bytecode):
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instruction = {}
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try:
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opcode = opcodes.opcodes[bytecode[i]]
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except KeyError:
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# invalid opcode
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disassembly.append({'opcode': "INVALID"})
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i += 1
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continue
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instruction['opcode'] = opcode[0]
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m = re.search(regex_PUSH, opcode[0])
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if m:
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argument = bytecode[i+1:i+1+int(m.group(1))]
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instruction['argument'] = codecs.encode(argument, "hex_codec")
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i += int(m.group(1))
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disassembly.append(instruction)
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i += 1
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return disassembly
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def assemble(disassembly):
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bytecode = b""
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for instruction in disassembly:
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try:
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opcode = get_opcode_from_name(instruction['opcode'])
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except RuntimeError:
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opcode = 0xbb
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bytecode += opcode.to_bytes(1, byteorder='big')
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if 'argument' in instruction:
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bytecode += bytes(instruction['argument'], 'ascii')
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return bytecode
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