"""This module contains the detection code to find multiple sends occurring in
a single transaction."""
from copy import copy
from typing import cast, List
from mythril.analysis.issue_annotation import IssueAnnotation
from mythril.analysis.report import Issue
from mythril.analysis.solver import get_transaction_sequence, UnsatError
from mythril.analysis.swc_data import MULTIPLE_SENDS
from mythril.analysis.module.base import DetectionModule, EntryPoint
from mythril.laser.ethereum.state.annotation import StateAnnotation
from mythril.laser.ethereum.state.global_state import GlobalState
from mythril.laser.smt import And
import logging
log = logging.getLogger(__name__)
[docs]
class MultipleSendsAnnotation(StateAnnotation):
def __init__(self) -> None:
self.call_offsets = [] # type: List[int]
def __copy__(self):
result = MultipleSendsAnnotation()
result.call_offsets = copy(self.call_offsets)
return result
[docs]
class MultipleSends(DetectionModule):
"""This module checks for multiple sends in a single transaction."""
name = "Multiple external calls in the same transaction"
swc_id = MULTIPLE_SENDS
description = "Check for multiple sends in a single transaction"
entry_point = EntryPoint.CALLBACK
pre_hooks = ["CALL", "DELEGATECALL", "STATICCALL", "CALLCODE", "RETURN", "STOP"]
def _execute(self, state: GlobalState) -> None:
return self._analyze_state(state)
def _analyze_state(self, state: GlobalState):
"""
:param state: the current state
:return: returns the issues for that corresponding state
"""
instruction = state.get_current_instruction()
annotations = cast(
List[MultipleSendsAnnotation],
list(state.get_annotations(MultipleSendsAnnotation)),
)
if len(annotations) == 0:
state.annotate(MultipleSendsAnnotation())
annotations = cast(
List[MultipleSendsAnnotation],
list(state.get_annotations(MultipleSendsAnnotation)),
)
call_offsets = annotations[0].call_offsets
if instruction["opcode"] in ["CALL", "DELEGATECALL", "STATICCALL", "CALLCODE"]:
call_offsets.append(state.get_current_instruction()["address"])
else: # RETURN or STOP
for offset in call_offsets[1:]:
try:
transaction_sequence = get_transaction_sequence(
state, state.world_state.constraints
)
except UnsatError:
continue
description_tail = (
"This call is executed following another call within the same transaction. It is possible "
"that the call never gets executed if a prior call fails permanently. This might be caused "
"intentionally by a malicious callee. If possible, refactor the code such that each transaction "
"only executes one external call or "
"make sure that all callees can be trusted (i.e. they’re part of your own codebase)."
)
issue = Issue(
contract=state.environment.active_account.contract_name,
function_name=state.environment.active_function_name,
address=offset,
swc_id=MULTIPLE_SENDS,
bytecode=state.environment.code.bytecode,
title="Multiple Calls in a Single Transaction",
severity="Low",
description_head="Multiple calls are executed in the same transaction.",
description_tail=description_tail,
gas_used=(state.mstate.min_gas_used, state.mstate.max_gas_used),
transaction_sequence=transaction_sequence,
)
state.annotate(
IssueAnnotation(
conditions=[And(*state.world_state.constraints)],
issue=issue,
detector=self,
)
)
return [issue]
return []
detector = MultipleSends()