From 6bbab6855a12cabec3f22cf7fcbcde8408c3b9c3 Mon Sep 17 00:00:00 2001
From: Joran Honig <joran.honig@gmail.com>
Date: Thu, 5 Jul 2018 11:30:28 +0200
Subject: [PATCH 01/18] Add return statement

---
 mythril/laser/ethereum/call.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/mythril/laser/ethereum/call.py b/mythril/laser/ethereum/call.py
index 23145b9e..483894ce 100644
--- a/mythril/laser/ethereum/call.py
+++ b/mythril/laser/ethereum/call.py
@@ -111,10 +111,13 @@ def get_callee_account(global_state, callee_address, dynamic_loader):
     if code is None:
         logging.info("No code returned, not a contract account?")
         raise ValueError()
+    logging.info("Dependency loaded: " + callee_address)
 
-    accounts[callee_address] = Account(callee_address, code, callee_address)
+    callee_account = Account(callee_address, code, callee_address)
+    accounts[callee_address] = callee_account
+
+    return callee_account
 
-    logging.info("Dependency loaded: " + callee_address)
 
 
 def get_call_data(global_state, memory_start, memory_size, pad=True):

From 5c0e65b2d80981ecfd8507acc598a80932c6ef9a Mon Sep 17 00:00:00 2001
From: Joran Honig <joran.honig@gmail.com>
Date: Thu, 5 Jul 2018 11:55:29 +0200
Subject: [PATCH 02/18] Implementation of a depth first search search strategy

---
 mythril/laser/ethereum/strategy/__init__.py |  0
 mythril/laser/ethereum/strategy/basic.py    | 17 +++++++++++++++++
 mythril/laser/ethereum/svm.py               | 13 ++++---------
 3 files changed, 21 insertions(+), 9 deletions(-)
 create mode 100644 mythril/laser/ethereum/strategy/__init__.py
 create mode 100644 mythril/laser/ethereum/strategy/basic.py

diff --git a/mythril/laser/ethereum/strategy/__init__.py b/mythril/laser/ethereum/strategy/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/mythril/laser/ethereum/strategy/basic.py b/mythril/laser/ethereum/strategy/basic.py
new file mode 100644
index 00000000..4dc2d968
--- /dev/null
+++ b/mythril/laser/ethereum/strategy/basic.py
@@ -0,0 +1,17 @@
+class DepthFirstSearchStrategy:
+
+    def __init__(self, content, max_depth):
+        self.content = content
+        self.max_depth = max_depth
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        try:
+            global_state = self.content.pop(0)
+            if global_state.mstate.depth >= self.max_depth:
+                return self.__next__()
+            return global_state
+        except IndexError:
+            raise StopIteration()
diff --git a/mythril/laser/ethereum/svm.py b/mythril/laser/ethereum/svm.py
index 0001f8e0..fc835662 100644
--- a/mythril/laser/ethereum/svm.py
+++ b/mythril/laser/ethereum/svm.py
@@ -3,6 +3,7 @@ import logging
 from mythril.laser.ethereum.state import GlobalState, Environment, CalldataType, Account
 from mythril.laser.ethereum.instructions import Instruction
 from mythril.laser.ethereum.cfg import NodeFlags, Node, Edge, JumpType
+from mythril.laser.ethereum.strategy.basic import DepthFirstSearchStrategy
 
 TT256 = 2 ** 256
 TT256M1 = 2 ** 256 - 1
@@ -31,7 +32,7 @@ class LaserEVM:
         self.dynamic_loader = dynamic_loader
 
         self.work_list = []
-        self.max_depth = max_depth
+        self.strategy = DepthFirstSearchStrategy(self.work_list, max_depth)
 
         logging.info("LASER EVM initialized with dynamic loader: " + str(dynamic_loader))
 
@@ -57,20 +58,14 @@ class LaserEVM:
         initial_node.states.append(global_state)
 
         # Empty the work_list before starting an execution
-        self.work_list = [global_state]
+        self.work_list.append(global_state)
         self._sym_exec()
 
         logging.info("Execution complete")
         logging.info("%d nodes, %d edges, %d total states", len(self.nodes), len(self.edges), self.total_states)
 
     def _sym_exec(self):
-        while True:
-            try:
-                global_state = self.work_list.pop(0)
-                if global_state.mstate.depth >= self.max_depth: continue
-            except IndexError:
-                return
-
+        for global_state in self.strategy:
             try:
                 new_states, op_code = self.execute_state(global_state)
             except NotImplementedError:

From b973a1686f269044e670704b56c07ca79336c29c Mon Sep 17 00:00:00 2001
From: Joran Honig <joran.honig@gmail.com>
Date: Thu, 5 Jul 2018 12:01:26 +0200
Subject: [PATCH 03/18] Add documentation and fix pop

---
 mythril/laser/ethereum/strategy/basic.py | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/mythril/laser/ethereum/strategy/basic.py b/mythril/laser/ethereum/strategy/basic.py
index 4dc2d968..754cd3ef 100644
--- a/mythril/laser/ethereum/strategy/basic.py
+++ b/mythril/laser/ethereum/strategy/basic.py
@@ -1,17 +1,29 @@
-class DepthFirstSearchStrategy:
+"""
+This module implements basic symbolic execution search strategies
+"""
+
 
-    def __init__(self, content, max_depth):
-        self.content = content
+class DepthFirstSearchStrategy:
+    """
+    Implements a depth first search strategy
+    I.E. Follow one path to a leaf, and then continue to the next one
+    """
+    def __init__(self, work_list, max_depth):
+        self.work_list = work_list
         self.max_depth = max_depth
 
     def __iter__(self):
         return self
 
     def __next__(self):
+        """ Picks the next state to execute """
         try:
-            global_state = self.content.pop(0)
+            # This strategies assumes that new states are appended at the end of the work_list
+            # By taking the last element we effectively pick the "newest" states, which amounts to dfs
+            global_state = self.work_list.pop()
             if global_state.mstate.depth >= self.max_depth:
                 return self.__next__()
             return global_state
         except IndexError:
             raise StopIteration()
+

From b82717afedda02b94fed56e5abbed7a66480f879 Mon Sep 17 00:00:00 2001
From: Joran Honig <joran.honig@gmail.com>
Date: Thu, 5 Jul 2018 12:05:08 +0200
Subject: [PATCH 04/18] re add max depth for now

---
 mythril/laser/ethereum/svm.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mythril/laser/ethereum/svm.py b/mythril/laser/ethereum/svm.py
index fc835662..1ceb3740 100644
--- a/mythril/laser/ethereum/svm.py
+++ b/mythril/laser/ethereum/svm.py
@@ -33,6 +33,7 @@ class LaserEVM:
 
         self.work_list = []
         self.strategy = DepthFirstSearchStrategy(self.work_list, max_depth)
+        self.max_depth = max_depth
 
         logging.info("LASER EVM initialized with dynamic loader: " + str(dynamic_loader))
 

From eb963d38fde46d39e91b4be14a68263b869d35d7 Mon Sep 17 00:00:00 2001
From: Joran Honig <joran.honig@gmail.com>
Date: Thu, 5 Jul 2018 12:16:18 +0200
Subject: [PATCH 05/18] Implement depth first search

---
 mythril/laser/ethereum/strategy/basic.py | 25 ++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/mythril/laser/ethereum/strategy/basic.py b/mythril/laser/ethereum/strategy/basic.py
index 754cd3ef..33dca443 100644
--- a/mythril/laser/ethereum/strategy/basic.py
+++ b/mythril/laser/ethereum/strategy/basic.py
@@ -27,3 +27,28 @@ class DepthFirstSearchStrategy:
         except IndexError:
             raise StopIteration()
 
+
+class BreadthFirstSearchStrategy:
+    """
+    Implements a breadth first search strategy
+    I.E. Execute all states of a "level" before continuing
+    """
+    def __init__(self, work_list, max_depth):
+        self.work_list = work_list
+        self.max_depth = max_depth
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        """ Picks the next state to execute """
+        try:
+            # This strategies assumes that new states are appended at the end of the work_list
+            # By taking the first element we effectively pick the "oldest" states, which amounts to bfs
+            global_state = self.work_list.pop(0)
+            if global_state.mstate.depth >= self.max_depth:
+                return self.__next__()
+            return global_state
+        except IndexError:
+            raise StopIteration()
+

From 25f76368bca4e7865811fcc578a13ac10a09f8ce Mon Sep 17 00:00:00 2001
From: Nikhil Parasaram <tommycjniko@gmail.com>
Date: Fri, 6 Jul 2018 21:45:18 +0530
Subject: [PATCH 06/18] Support 0x0 for extcodesize

---
 mythril/laser/ethereum/instructions.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mythril/laser/ethereum/instructions.py b/mythril/laser/ethereum/instructions.py
index 4d90da95..64e87937 100644
--- a/mythril/laser/ethereum/instructions.py
+++ b/mythril/laser/ethereum/instructions.py
@@ -529,8 +529,12 @@ class Instruction:
             logging.info("error accessing contract storage due to: " + str(e))
             state.stack.append(BitVec("extcodesize_" + str(addr), 256))
             return [global_state]
+        
+        if code is None:
+            state.stack.append(0)
+        else:
+            state.stack.append(len(code.bytecode) // 2)
 
-        state.stack.append(len(code.bytecode) // 2)
         return [global_state]
 
     @instruction

From 24fad14cbd498e49834cf22b3f043bfe66a7bd39 Mon Sep 17 00:00:00 2001
From: Nikhil Parasaram <tommycjniko@gmail.com>
Date: Fri, 6 Jul 2018 22:25:39 +0530
Subject: [PATCH 07/18] fix ethereum to 2.3.1

---
 requirements.txt | 2 +-
 setup.py         | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/requirements.txt b/requirements.txt
index 13e88c78..aad67f69 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,7 +2,7 @@ configparser>=3.5.0
 coverage
 eth_abi>=1.0.0
 eth-account>=0.1.0a2
-ethereum>=2.3.0
+ethereum==2.3.1
 eth-hash>=0.1.0
 eth-keyfile>=0.5.1
 eth-keys>=0.2.0b3
diff --git a/setup.py b/setup.py
index 3cbf5f97..0e7c624d 100755
--- a/setup.py
+++ b/setup.py
@@ -305,7 +305,7 @@ setup(
     packages=find_packages(exclude=['contrib', 'docs', 'tests']),
 
     install_requires=[
-        'ethereum>=2.3.0',
+        'ethereum==2.3.1',
         'z3-solver>=4.5',
         'requests',
         'py-solc',

From d0efd35ce25a817415c17e82ee4d734c3f4e17d4 Mon Sep 17 00:00:00 2001
From: Nikhil Parasaram <tommycjniko@gmail.com>
Date: Sat, 7 Jul 2018 19:19:26 +0530
Subject: [PATCH 08/18] connect to infura with -l

---
 mythril/mythril.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mythril/mythril.py b/mythril/mythril.py
index b63cc137..a72a82d7 100644
--- a/mythril/mythril.py
+++ b/mythril/mythril.py
@@ -335,9 +335,9 @@ class Mythril(object):
                     verbose_report=False, max_depth=12):
 
         all_issues = []
+        if self.dynld and self.eth is None:
+            self.set_api_rpc_infura()
         for contract in (contracts or self.contracts):
-            if self.eth is None:
-                self.set_api_rpc_infura()
             sym = SymExecWrapper(contract, address,
                                  dynloader=DynLoader(self.eth) if self.dynld else None,
                                  max_depth=max_depth)

From 290aaf81988e55366100c900dae4bb5b767c499e Mon Sep 17 00:00:00 2001
From: Joran Honig <joran.honig@gmail.com>
Date: Sat, 7 Jul 2018 22:16:01 +0200
Subject: [PATCH 09/18] Add condition not 0

---
 mythril/laser/ethereum/call.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mythril/laser/ethereum/call.py b/mythril/laser/ethereum/call.py
index 483894ce..58eafed3 100644
--- a/mythril/laser/ethereum/call.py
+++ b/mythril/laser/ethereum/call.py
@@ -36,7 +36,7 @@ def get_call_parameters(global_state, dynamic_loader, with_value=False):
     callee_account = None
     call_data, call_data_type = get_call_data(global_state, meminstart, meminsz, False)
 
-    if int(callee_address, 16) >= 5:
+    if int(callee_address, 16) >= 5 or int(callee_address) != 0:
         call_data, call_data_type = get_call_data(global_state, meminstart, meminsz)
         callee_account = get_callee_account(global_state, callee_address, dynamic_loader)
 

From c3d1eb85c36ccb0f46f638f01d05f90d82b6dbb5 Mon Sep 17 00:00:00 2001
From: Joran Honig <joran.honig@gmail.com>
Date: Sat, 7 Jul 2018 22:16:47 +0200
Subject: [PATCH 10/18] Pass None as node

---
 mythril/laser/ethereum/instructions.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mythril/laser/ethereum/instructions.py b/mythril/laser/ethereum/instructions.py
index 4d90da95..72451f48 100644
--- a/mythril/laser/ethereum/instructions.py
+++ b/mythril/laser/ethereum/instructions.py
@@ -913,7 +913,7 @@ class Instruction:
                                          value,
                                          environment.origin,
                                          calldata_type=call_data_type)
-        new_global_state = GlobalState(global_state.accounts, callee_environment, MachineState(gas))
+        new_global_state = GlobalState(global_state.accounts, callee_environment, None, MachineState(gas))
         new_global_state.mstate.depth = global_state.mstate.depth + 1
         new_global_state.mstate.constraints = copy(global_state.mstate.constraints)
         return [global_state]
@@ -940,7 +940,7 @@ class Instruction:
         environment.caller = environment.address
         environment.calldata = call_data
 
-        new_global_state = GlobalState(global_state.accounts, environment, MachineState(gas))
+        new_global_state = GlobalState(global_state.accounts, environment, None, MachineState(gas))
         new_global_state.mstate.depth = global_state.mstate.depth + 1
         new_global_state.mstate.constraints = copy(global_state.mstate.constraints)
 
@@ -968,7 +968,7 @@ class Instruction:
         environment.code = callee_account.code
         environment.calldata = call_data
 
-        new_global_state = GlobalState(global_state.accounts, environment, MachineState(gas))
+        new_global_state = GlobalState(global_state.accounts, environment, None, MachineState(gas))
         new_global_state.mstate.depth = global_state.mstate.depth + 1
         new_global_state.mstate.constraints = copy(global_state.mstate.constraints)
 

From 09c41deb6370ffdb548e9df04d7722e55b38c39b Mon Sep 17 00:00:00 2001
From: Joran Honig <joran.honig@gmail.com>
Date: Sat, 7 Jul 2018 22:43:01 +0200
Subject: [PATCH 11/18] Fix node issue

---
 mythril/laser/ethereum/instructions.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mythril/laser/ethereum/instructions.py b/mythril/laser/ethereum/instructions.py
index 72451f48..56456fdd 100644
--- a/mythril/laser/ethereum/instructions.py
+++ b/mythril/laser/ethereum/instructions.py
@@ -913,7 +913,7 @@ class Instruction:
                                          value,
                                          environment.origin,
                                          calldata_type=call_data_type)
-        new_global_state = GlobalState(global_state.accounts, callee_environment, None, MachineState(gas))
+        new_global_state = GlobalState(global_state.accounts, callee_environment, global_state.node, MachineState(gas))
         new_global_state.mstate.depth = global_state.mstate.depth + 1
         new_global_state.mstate.constraints = copy(global_state.mstate.constraints)
         return [global_state]
@@ -940,7 +940,7 @@ class Instruction:
         environment.caller = environment.address
         environment.calldata = call_data
 
-        new_global_state = GlobalState(global_state.accounts, environment, None, MachineState(gas))
+        new_global_state = GlobalState(global_state.accounts, environment, global_state.node, MachineState(gas))
         new_global_state.mstate.depth = global_state.mstate.depth + 1
         new_global_state.mstate.constraints = copy(global_state.mstate.constraints)
 
@@ -968,7 +968,7 @@ class Instruction:
         environment.code = callee_account.code
         environment.calldata = call_data
 
-        new_global_state = GlobalState(global_state.accounts, environment, None, MachineState(gas))
+        new_global_state = GlobalState(global_state.accounts, environment, global_state.node, MachineState(gas))
         new_global_state.mstate.depth = global_state.mstate.depth + 1
         new_global_state.mstate.constraints = copy(global_state.mstate.constraints)
 

From 7c638272cbe936ba40cea9d0b5552e0edebeb6aa Mon Sep 17 00:00:00 2001
From: Joran Honig <joran.honig@gmail.com>
Date: Sat, 7 Jul 2018 23:12:49 +0200
Subject: [PATCH 12/18] Reverse comparison

---
 mythril/laser/ethereum/call.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mythril/laser/ethereum/call.py b/mythril/laser/ethereum/call.py
index 58eafed3..63d09837 100644
--- a/mythril/laser/ethereum/call.py
+++ b/mythril/laser/ethereum/call.py
@@ -36,7 +36,7 @@ def get_call_parameters(global_state, dynamic_loader, with_value=False):
     callee_account = None
     call_data, call_data_type = get_call_data(global_state, meminstart, meminsz, False)
 
-    if int(callee_address, 16) >= 5 or int(callee_address) != 0:
+    if int(callee_address, 16) >= 5 or int(callee_address) == 0:
         call_data, call_data_type = get_call_data(global_state, meminstart, meminsz)
         callee_account = get_callee_account(global_state, callee_address, dynamic_loader)
 

From 83c5eca66bc82ca500e6fb75e7de66c34559f734 Mon Sep 17 00:00:00 2001
From: tintinweb <tintinweb@oststrom.com>
Date: Tue, 3 Jul 2018 23:05:24 +0200
Subject: [PATCH 13/18] added online lookup for signature hashes via
 4bytes.directory

---
 mythril/disassembler/disassembly.py | 26 +++--------
 mythril/support/signatures.py       | 67 +++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+), 20 deletions(-)

diff --git a/mythril/disassembler/disassembly.py b/mythril/disassembler/disassembly.py
index 787f297f..b7414529 100644
--- a/mythril/disassembler/disassembly.py
+++ b/mythril/disassembler/disassembly.py
@@ -1,6 +1,5 @@
 from mythril.ether import asm,util
-import os
-import json
+from mythril.support.signatures import Signatures
 import logging
 
 
@@ -13,21 +12,11 @@ class Disassembly:
         self.addr_to_func = {}
         self.bytecode = code
 
+        signatures = Signatures(enable_online_lookkup=True)  # control if you want to have online sighash lookups
         try:
-            mythril_dir = os.environ['MYTHRIL_DIR']
-        except KeyError:
-            mythril_dir = os.path.join(os.path.expanduser('~'), ".mythril")
-
-        # Load function signatures
-
-        signatures_file = os.path.join(mythril_dir, 'signatures.json')
-
-        if not os.path.exists(signatures_file):
-            logging.info("Missing function signature file. Resolving of function names disabled.")
-            signatures = {}
-        else:
-            with open(signatures_file) as f:
-                signatures = json.load(f)
+            signatures.open()  # open from default locations
+        except FileNotFoundError:
+            logging.info("Missing function signature file. Resolving of function names from disabled.")
 
         # Parse jump table & resolve function names
 
@@ -36,7 +25,7 @@ class Disassembly:
         for i in jmptable_indices:
             func_hash = self.instruction_list[i]['argument']
             try:
-                func_name = signatures[func_hash]
+                func_name = signatures.get(func_hash)  # tries local cache, file and optional online lookup
             except KeyError:
                 func_name = "_function_" + func_hash
 
@@ -49,8 +38,5 @@ class Disassembly:
             except:
                 continue
 
-
-
     def get_easm(self):
-
         return asm.instruction_list_to_easm(self.instruction_list)
diff --git a/mythril/support/signatures.py b/mythril/support/signatures.py
index 0431dd21..5fb21737 100644
--- a/mythril/support/signatures.py
+++ b/mythril/support/signatures.py
@@ -1,7 +1,17 @@
 import re
+import os
+import logging
+import json
 from ethereum import utils
 
+try:
+    # load if available but do not fail
+    import ethereum_input_decoder
+except ImportError:
+    ethereum_input_decoder = None
 
+
+# TODO: tintinweb: move this and signature functionality from mythril.py to class Signatures to have one single interface.
 def add_signatures_from_file(file, sigs={}):
 
     funcs = []
@@ -42,3 +52,60 @@ def add_signatures_from_file(file, sigs={}):
             signature = re.sub(r'\s', '', signature)
 
             sigs["0x" + utils.sha3(signature)[:4].hex()] = signature
+
+
+class Signatures(object):
+
+    def __init__(self, enable_online_lookkup=True):
+        self.signatures = {}  # signatures in-mem cache
+        self.enable_online_lookup =enable_online_lookkup  # enable online funcsig resolving
+
+    def open(self, path=None):
+        if not path:
+            #  try default locations
+            try:
+                mythril_dir = os.environ['MYTHRIL_DIR']
+            except KeyError:
+                mythril_dir = os.path.join(os.path.expanduser('~'), ".mythril")
+            path = os.path.join(mythril_dir, 'signatures.json')
+
+        if not os.path.exists(path):
+            raise FileNotFoundError("Missing function signature file. Resolving of function names disabled.")
+
+        with open(path) as f:
+            sigs = json.load(f)
+
+        # normalize it to {sighash:list(signatures,...)}
+        for sighash,funcsig in sigs.items():
+            self.signatures.setdefault(sighash, [])
+            self.signatures[sighash].append(funcsig)
+
+        return self
+
+    def get(self, sighash):
+        """
+        get a function signature for a sighash
+        1) try local cache
+        2) try online lookup
+        :param sighash:
+        :return: list of function signatures
+        """
+        if not self.signatures.get(sighash) and self.enable_online_lookup:
+            self.signatures[sighash] = Signatures.lookup_online(sighash)  # might return multiple sigs
+        return self.signatures.get(sighash)
+
+
+    @staticmethod
+    def lookup_online(sighash):
+        """
+        Lookup function signatures from 4bytes.directory.
+        //tintinweb: the smart-contract-sanctuary project dumps contracts from etherscan.io and feeds them into
+                     4bytes.directory.
+                     https://github.com/tintinweb/smart-contract-sanctuary
+
+        :param s: function signature as hexstr
+        :return: a list of possible function signatures for this hash
+        """
+        if not ethereum_input_decoder:
+            return None
+        return list(ethereum_input_decoder.decoder.FourByteDirectory.lookup_signatures(sighash))

From cdd27383970244d943a7de89d8c58d0910e95702 Mon Sep 17 00:00:00 2001
From: tintinweb <tintinweb@oststrom.com>
Date: Tue, 3 Jul 2018 23:12:48 +0200
Subject: [PATCH 14/18] result to online lookup can be ambiguous. use first
 item and note this in disassembly

---
 mythril/disassembler/disassembly.py | 14 +++++++++++---
 mythril/support/signatures.py       | 13 ++++++++-----
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/mythril/disassembler/disassembly.py b/mythril/disassembler/disassembly.py
index b7414529..de1c9bad 100644
--- a/mythril/disassembler/disassembly.py
+++ b/mythril/disassembler/disassembly.py
@@ -12,11 +12,11 @@ class Disassembly:
         self.addr_to_func = {}
         self.bytecode = code
 
-        signatures = Signatures(enable_online_lookkup=True)  # control if you want to have online sighash lookups
+        signatures = Signatures(enable_online_lookup=True)  # control if you want to have online sighash lookups
         try:
             signatures.open()  # open from default locations
         except FileNotFoundError:
-            logging.info("Missing function signature file. Resolving of function names from disabled.")
+            logging.info("Missing function signature file. Resolving of function names from signature file disabled.")
 
         # Parse jump table & resolve function names
 
@@ -25,7 +25,15 @@ class Disassembly:
         for i in jmptable_indices:
             func_hash = self.instruction_list[i]['argument']
             try:
-                func_name = signatures.get(func_hash)  # tries local cache, file and optional online lookup
+                # tries local cache, file and optional online lookup
+                # may return more than one function signature. since we cannot probe for the correct one we'll use the first
+                func_names = signatures.get(func_hash)
+                if len(func_names) > 1:
+                    # ambigious result
+                    func_name = "**ambiguous** %s"%func_names[0]  # return first hit but note that result was ambiguous
+                else:
+                    # only one item
+                    func_name = func_names[0]
             except KeyError:
                 func_name = "_function_" + func_hash
 
diff --git a/mythril/support/signatures.py b/mythril/support/signatures.py
index 5fb21737..04fde734 100644
--- a/mythril/support/signatures.py
+++ b/mythril/support/signatures.py
@@ -56,9 +56,9 @@ def add_signatures_from_file(file, sigs={}):
 
 class Signatures(object):
 
-    def __init__(self, enable_online_lookkup=True):
+    def __init__(self, enable_online_lookup=True):
         self.signatures = {}  # signatures in-mem cache
-        self.enable_online_lookup =enable_online_lookkup  # enable online funcsig resolving
+        self.enable_online_lookup =enable_online_lookup  # enable online funcsig resolving
 
     def open(self, path=None):
         if not path:
@@ -91,14 +91,17 @@ class Signatures(object):
         :return: list of function signatures
         """
         if not self.signatures.get(sighash) and self.enable_online_lookup:
-            self.signatures[sighash] = Signatures.lookup_online(sighash)  # might return multiple sigs
-        return self.signatures.get(sighash)
+            funcsigs = Signatures.lookup_online(sighash)  # might return multiple sigs
+            if funcsigs:
+                # only store if we get at least one result
+                self.signatures[sighash] = funcsigs
+        return self.signatures[sighash]  # raise keyerror
 
 
     @staticmethod
     def lookup_online(sighash):
         """
-        Lookup function signatures from 4bytes.directory.
+        Lookup function signatures from 4byte.directory.
         //tintinweb: the smart-contract-sanctuary project dumps contracts from etherscan.io and feeds them into
                      4bytes.directory.
                      https://github.com/tintinweb/smart-contract-sanctuary

From 73efcffde213e1f17aec220611b1d6ac58a38d7d Mon Sep 17 00:00:00 2001
From: tintinweb <tintinweb@oststrom.com>
Date: Wed, 4 Jul 2018 19:55:11 +0200
Subject: [PATCH 15/18] rebase off master refactor function signature handling 
 -> one single class to handle signatures  -> Signatures().get(sighash) and
 Signatures()[sighash] interfaces  -> added simple file locking mechanism ref
 #294  -> fix signature caching (avoid looking up same hash multiple times)

---
 mythril/disassembler/disassembly.py |  11 +-
 mythril/mythril.py                  |  58 +++----
 mythril/support/signatures.py       | 232 ++++++++++++++++++++++------
 3 files changed, 210 insertions(+), 91 deletions(-)

diff --git a/mythril/disassembler/disassembly.py b/mythril/disassembler/disassembly.py
index de1c9bad..a20d4ffe 100644
--- a/mythril/disassembler/disassembly.py
+++ b/mythril/disassembler/disassembly.py
@@ -1,9 +1,9 @@
 from mythril.ether import asm,util
-from mythril.support.signatures import Signatures
+from mythril.support.signatures import SignatureDb
 import logging
 
 
-class Disassembly:
+class Disassembly(object):
 
     def __init__(self, code):
         self.instruction_list = asm.disassemble(util.safe_decode(code))
@@ -12,7 +12,7 @@ class Disassembly:
         self.addr_to_func = {}
         self.bytecode = code
 
-        signatures = Signatures(enable_online_lookup=True)  # control if you want to have online sighash lookups
+        signatures = SignatureDb(enable_online_lookup=True)  # control if you want to have online sighash lookups
         try:
             signatures.open()  # open from default locations
         except FileNotFoundError:
@@ -30,7 +30,7 @@ class Disassembly:
                 func_names = signatures.get(func_hash)
                 if len(func_names) > 1:
                     # ambigious result
-                    func_name = "**ambiguous** %s"%func_names[0]  # return first hit but note that result was ambiguous
+                    func_name = "**ambiguous** %s" % func_names[0]  # return first hit but note that result was ambiguous
                 else:
                     # only one item
                     func_name = func_names[0]
@@ -46,5 +46,8 @@ class Disassembly:
             except:
                 continue
 
+        signatures.write()  # store resolved signatures (potentially resolved online)
+
     def get_easm(self):
+        # todo: tintinweb - print funcsig resolved data from self.addr_to_func?
         return asm.instruction_list_to_easm(self.instruction_list)
diff --git a/mythril/mythril.py b/mythril/mythril.py
index a72a82d7..0a85366b 100644
--- a/mythril/mythril.py
+++ b/mythril/mythril.py
@@ -78,8 +78,6 @@ class Mythril(object):
         mythril.get_state_variable_from_storage(args)
 
     """
-
-
     def __init__(self, solv=None,
                  solc_args=None, dynld=False):
 
@@ -88,7 +86,17 @@ class Mythril(object):
         self.dynld = dynld
 
         self.mythril_dir = self._init_mythril_dir()
-        self.signatures_file, self.sigs = self._init_signatures()
+
+        self.sigs = signatures.SignatureDb()
+        try:
+            self.sigs.open()  # tries mythril_dir/signatures.json by default (provide path= arg to make this configurable)
+        except FileNotFoundError as fnfe:
+            logging.info(
+                "No signature database found. Creating database if sigs are loaded in: " + self.sigs.signatures_file + "\n" +
+                "Consider replacing it with the pre-initialized database at https://raw.githubusercontent.com/ConsenSys/mythril/master/signatures.json")
+        except json.JSONDecodeError as jde:
+            raise CriticalError("Invalid JSON in signatures file " + self.sigs.signatures_file + "\n" + str(jde))
+
         self.solc_binary = self._init_solc_binary(solv)
         self.leveldb_dir = self._init_config()
 
@@ -110,33 +118,6 @@ class Mythril(object):
             os.mkdir(mythril_dir)
         return mythril_dir
 
-    def _init_signatures(self):
-
-        # If no function signature file exists, create it. Function signatures from Solidity source code are added automatically.
-
-        signatures_file = os.path.join(self.mythril_dir, 'signatures.json')
-
-        sigs = {}
-        if not os.path.exists(signatures_file):
-            logging.info("No signature database found. Creating empty database: " + signatures_file + "\n" +
-                         "Consider replacing it with the pre-initialized database at https://raw.githubusercontent.com/ConsenSys/mythril/master/signatures.json")
-            with open(signatures_file, 'a') as f:
-                json.dump({}, f)
-
-        with open(signatures_file) as f:
-            try:
-                sigs = json.load(f)
-            except json.JSONDecodeError as e:
-                raise CriticalError("Invalid JSON in signatures file " + signatures_file + "\n" + str(e))
-        return signatures_file, sigs
-
-    def _update_signatures(self, jsonsigs):
-        # Save updated function signatures
-        with open(self.signatures_file, 'w') as f:
-            json.dump(jsonsigs, f)
-
-        self.sigs = jsonsigs
-
     def _init_config(self):
 
         # If no config file exists, create it. Default LevelDB path is specified based on OS
@@ -300,27 +281,32 @@ class Mythril(object):
             file = os.path.expanduser(file)
 
             try:
-                signatures.add_signatures_from_file(file, self.sigs)
-                self._update_signatures(self.sigs)
+                # import signatures from solidity source
+                with open(file, encoding="utf-8") as f:
+                    self.sigs.import_from_solidity_source(f.read())
+
                 contract = SolidityContract(file, contract_name, solc_args=self.solc_args)
                 logging.info("Analyzing contract %s:%s" % (file, contract.name))
             except FileNotFoundError:
-                 raise CriticalError("Input file not found: " + file)
+                raise CriticalError("Input file not found: " + file)
             except CompilerError as e:
-                 raise CriticalError(e)
+                raise CriticalError(e)
             except NoContractFoundError:
                 logging.info("The file " + file + " does not contain a compilable contract.")
             else:
                 self.contracts.append(contract)
                 contracts.append(contract)
 
+        # Save updated function signatures
+        self.sigs.write()  # dump signatures to disk (previously opened file or default location)
+
         return address, contracts
 
     def dump_statespace(self, contract, address=None, max_depth=12):
 
         sym = SymExecWrapper(contract, address,
-            dynloader=DynLoader(self.eth) if self.dynld else None,
-            max_depth=max_depth)
+                             dynloader=DynLoader(self.eth) if self.dynld else None,
+                             max_depth=max_depth)
 
         return get_serializable_statespace(sym)
 
diff --git a/mythril/support/signatures.py b/mythril/support/signatures.py
index 04fde734..af86abc4 100644
--- a/mythril/support/signatures.py
+++ b/mythril/support/signatures.py
@@ -1,66 +1,90 @@
+#!/usr/bin/env python3
+# -*- coding: UTF-8 -*-
+"""mythril.py: Function Signature Database
+"""
 import re
 import os
-import logging
 import json
+import time
+import pathlib
+import logging
 from ethereum import utils
 
+# todo: tintinweb - make this a normal requirement? (deps: eth-abi and requests, both already required by mythril)
 try:
     # load if available but do not fail
     import ethereum_input_decoder
+    from ethereum_input_decoder.decoder import FourByteDirectoryOnlineLookupError
 except ImportError:
+    # fake it :)
     ethereum_input_decoder = None
+    FourByteDirectoryOnlineLookupError = Exception
 
 
-# TODO: tintinweb: move this and signature functionality from mythril.py to class Signatures to have one single interface.
-def add_signatures_from_file(file, sigs={}):
-
-    funcs = []
-
-    with open(file, encoding="utf-8") as f:
-
-        code = f.read()
-
-    funcs = re.findall(r'function[\s]+(\w+\([^\)]*\))', code, re.DOTALL)
-
-    for f in funcs:
+class SimpleFileLock(object):
+    # todo: replace with something more reliable. this is a quick shot on concurrency and might not work in all cases
 
-        f = re.sub(r'[\n]', '', f)
+    def __init__(self, path):
+        self.path = path
+        self.lockfile = pathlib.Path("%s.lck" % path)
+        self.locked = False
 
-        m = re.search(r'^([A-Za-z0-9_]+)', f)
+    def aquire(self, timeout=5):
+        if self.locked:
+            raise Exception("SimpleFileLock: lock already aquired")
 
-        if (m):
-
-            signature = m.group(1)
-
-            m = re.search(r'\((.*)\)', f)
-
-            _args = m.group(1).split(",")
-
-            types = []
+        t_end = time.time()+timeout
+        while time.time() < t_end:
+            # try to aquire lock
+            try:
+                self.lockfile.touch(mode=0o0000, exist_ok=False)  # touch the lockfile
+                # lockfile does not exist. we have a lock now
+                self.locked = True
+                return
+            except FileExistsError as fee:
+                # check if lockfile date exceeds age and cleanup lock
+                if time.time() > self.lockfile.stat().st_mtime + 60 * 5:
+                    self.release(force=True)  # cleanup old lockfile > 5mins
 
-            for arg in _args:
+                time.sleep(0.5)  # busywait is evil
+                continue
 
-                _type = arg.lstrip().split(" ")[0]
-                if _type == "uint":
-                    _type = "uint256"
+        raise Exception("SimpleFileLock: timeout hit. failed to aquire lock: %s"% (time.time()-self.lockfile.stat().st_mtime))
 
-                types.append(_type)
+    def release(self, force=False):
+        if not force and not self.locked:
+            raise Exception("SimpleFileLock: aquire lock first")
 
-            typelist = ",".join(types)
-            signature += "(" + typelist + ")"
+        try:
+            self.lockfile.unlink()  # might throw if we force unlock and the file gets removed in the meantime. TOCTOU
+        except FileNotFoundError as fnfe:
+            logging.warning("SimpleFileLock: release(force=%s) on unavailable file. race? %r" % (force, fnfe))
 
-            signature = re.sub(r'\s', '', signature)
+        self.locked = False
 
-            sigs["0x" + utils.sha3(signature)[:4].hex()] = signature
 
 
-class Signatures(object):
+class SignatureDb(object):
 
     def __init__(self, enable_online_lookup=True):
+        """
+        Constr
+        :param enable_online_lookup: enable onlien signature hash lookup
+        """
         self.signatures = {}  # signatures in-mem cache
-        self.enable_online_lookup =enable_online_lookup  # enable online funcsig resolving
+        self.signatures_file = None
+        self.signatures_file_lock = None
+        self.enable_online_lookup = enable_online_lookup  # enable online funcsig resolving
+        self.online_lookup_miss = set()  # temporarily track misses from onlinedb to avoid requesting the same non-existent sighash multiple times
+        self.online_directory_unavailable_until = 0  # flag the online directory as unavailable for some time
 
     def open(self, path=None):
+        """
+        Open a function signature db from json file
+
+        :param path: specific path to signatures.json; default mythril location if not specified
+        :return: self
+        """
         if not path:
             #  try default locations
             try:
@@ -69,46 +93,152 @@ class Signatures(object):
                 mythril_dir = os.path.join(os.path.expanduser('~'), ".mythril")
             path = os.path.join(mythril_dir, 'signatures.json')
 
+        self.signatures_file = path  # store early to allow error handling to access the place we tried to load the file
+
         if not os.path.exists(path):
+            logging.debug("Signatures: file not found: %s" % path)
             raise FileNotFoundError("Missing function signature file. Resolving of function names disabled.")
 
-        with open(path) as f:
+        self.signatures_file_lock = SimpleFileLock(self.signatures_file)  # lock file to prevent concurrency issues
+        self.signatures_file_lock.aquire()  # try to aquire it within the next 10s
+
+        with open(path, 'r') as f:
             sigs = json.load(f)
 
+        self.signatures_file_lock.release()  # release lock
+
         # normalize it to {sighash:list(signatures,...)}
-        for sighash,funcsig in sigs.items():
+        for sighash, funcsig in sigs.items():
+            if isinstance(funcsig, list):
+                self.signatures = sigs  # keep original todo: tintinweb - super hacky. make sure signatures.json is initially in correct format fixme
+                break  # already normalized
             self.signatures.setdefault(sighash, [])
             self.signatures[sighash].append(funcsig)
 
         return self
 
-    def get(self, sighash):
+    def write(self, path=None, sync=True):
+        """
+        Write signatures database as json to file
+
+        :param path: specify path otherwise update the file that was loaded with open()
+        :param sync: lock signature file, load contents and merge it into memcached sighash db, then save it
+        :return: self
+        """
+        path = path or self.signatures_file
+        self.signatures_file_lock = SimpleFileLock(path)  # lock file to prevent concurrency issues
+        self.signatures_file_lock.aquire()  # try to aquire it within the next 10s
+
+        if sync and os.path.exists(path):
+            # reload and save if file exists
+            with open(path, 'r') as f:
+                sigs = json.load(f)
+
+            sigs.update(self.signatures)  # reload file and merge cached sigs into what we load from file
+            self.signatures = sigs
+
+        with open(path, 'w') as f:
+            json.dump(self.signatures, f)
+
+        self.signatures_file_lock.release()
+        return self
+
+    def get(self, sighash, timeout=2):
         """
         get a function signature for a sighash
         1) try local cache
-        2) try online lookup
-        :param sighash:
-        :return: list of function signatures
-        """
-        if not self.signatures.get(sighash) and self.enable_online_lookup:
-            funcsigs = Signatures.lookup_online(sighash)  # might return multiple sigs
-            if funcsigs:
-                # only store if we get at least one result
-                self.signatures[sighash] = funcsigs
+        2) try online lookup (if enabled; if not flagged as unavailable)
+        :param sighash: function signature hash as hexstr
+        :param timeout: online lookup timeout
+        :return: list of matching function signatures
+        """
+        if not sighash.startswith("0x"):
+            sighash = "0x%s" % sighash  # normalize sighash format
+
+        if self.enable_online_lookup and not self.signatures.get(sighash) and sighash not in self.online_lookup_miss and time.time() > self.online_directory_unavailable_until:
+            # online lookup enabled, and signature not in cache, sighash was not a miss earlier, and online directory not down
+            logging.debug("Signatures: performing online lookup for sighash %r" % sighash)
+            try:
+                funcsigs = SignatureDb.lookup_online(sighash, timeout=timeout)  # might return multiple sigs
+                if funcsigs:
+                    # only store if we get at least one result
+                    self.signatures[sighash] = funcsigs
+                else:
+                    # miss
+                    self.online_lookup_miss.add(sighash)
+            except FourByteDirectoryOnlineLookupError as fbdole:
+                self.online_directory_unavailable_until = time.time() + 2 * 60  # wait at least 2 mins to try again
+                logging.warning("online function signature lookup not available. will not try to lookup hash for the next 2 minutes. exception: %r" % fbdole)
         return self.signatures[sighash]  # raise keyerror
 
+    def __getitem__(self, item):
+        """
+        Provide dict interface Signatures()[sighash]
+        :param item: sighash
+        :return: list of matching signatures
+        """
+        return self.get(sighash=item)
+
+    def import_from_solidity_source(self, code):
+        """
+        Import Function Signatures from solidity source files
+        :param code: solidity source code
+        :return: self
+        """
+        self.signatures.update(SignatureDb.parse_function_signatures_from_solidity_source(code))
+        return self
 
     @staticmethod
-    def lookup_online(sighash):
+    def lookup_online(sighash, timeout=None, proxies=None):
         """
         Lookup function signatures from 4byte.directory.
         //tintinweb: the smart-contract-sanctuary project dumps contracts from etherscan.io and feeds them into
                      4bytes.directory.
                      https://github.com/tintinweb/smart-contract-sanctuary
 
-        :param s: function signature as hexstr
-        :return: a list of possible function signatures for this hash
+        :param sighash: function signature hash as hexstr
+        :param timeout: optional timeout for online lookup
+        :param proxies: optional proxy servers for online lookup
+        :return: a list of matching function signatures for this hash
         """
         if not ethereum_input_decoder:
             return None
-        return list(ethereum_input_decoder.decoder.FourByteDirectory.lookup_signatures(sighash))
+        return list(ethereum_input_decoder.decoder.FourByteDirectory.lookup_signatures(sighash,
+                                                                                       timeout=timeout,
+                                                                                       proxies=proxies))
+
+    @staticmethod
+    def parse_function_signatures_from_solidity_source(code):
+        """
+        Parse solidity sourcecode for function signatures and return the signature hash and function signature
+        :param code: solidity source code
+        :return: dictionary {sighash: function_signature}
+        """
+        sigs = {}
+
+        funcs = re.findall(r'function[\s]+(.*?\))', code, re.DOTALL)
+        for f in funcs:
+            f = re.sub(r'[\n]', '', f)
+            m = re.search(r'^([A-Za-z0-9_]+)', f)
+
+            if m:
+                signature = m.group(1)
+                m = re.search(r'\((.*)\)', f)
+                _args = m.group(1).split(",")
+                types = []
+
+                for arg in _args:
+                    _type = arg.lstrip().split(" ")[0]
+
+                    if _type == "uint":
+                        _type = "uint256"
+
+                    types.append(_type)
+
+                typelist = ",".join(types)
+                signature += "(" + typelist + ")"
+                signature = re.sub(r'\s', '', signature)
+                sigs["0x" + utils.sha3(signature)[:4].hex()] = signature
+
+        logging.debug("Signatures: parse soldiity found %d signatures" % len(sigs))
+        return sigs

From 6851754059888d46bd8484a87fcfd82436df1ed3 Mon Sep 17 00:00:00 2001
From: tintinweb <tintinweb@oststrom.com>
Date: Fri, 6 Jul 2018 18:00:47 +0200
Subject: [PATCH 16/18] remove unnecessary comment (todo) reuse SimpleFileLock
 instance if already set

Note: requests.[get|post|request](.., proxies=None) should be using the
default proxy settings (env)
Note: signature db path selection logic is currently not matching
mythril._init_config (but myhtril._init_mythril_dir)
---
 mythril/support/signatures.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mythril/support/signatures.py b/mythril/support/signatures.py
index af86abc4..e1582b68 100644
--- a/mythril/support/signatures.py
+++ b/mythril/support/signatures.py
@@ -99,7 +99,7 @@ class SignatureDb(object):
             logging.debug("Signatures: file not found: %s" % path)
             raise FileNotFoundError("Missing function signature file. Resolving of function names disabled.")
 
-        self.signatures_file_lock = SimpleFileLock(self.signatures_file)  # lock file to prevent concurrency issues
+        self.signatures_file_lock = self.signatures_file_lock or SimpleFileLock(self.signatures_file)  # lock file to prevent concurrency issues
         self.signatures_file_lock.aquire()  # try to aquire it within the next 10s
 
         with open(path, 'r') as f:
@@ -110,7 +110,7 @@ class SignatureDb(object):
         # normalize it to {sighash:list(signatures,...)}
         for sighash, funcsig in sigs.items():
             if isinstance(funcsig, list):
-                self.signatures = sigs  # keep original todo: tintinweb - super hacky. make sure signatures.json is initially in correct format fixme
+                self.signatures = sigs
                 break  # already normalized
             self.signatures.setdefault(sighash, [])
             self.signatures[sighash].append(funcsig)
@@ -126,7 +126,7 @@ class SignatureDb(object):
         :return: self
         """
         path = path or self.signatures_file
-        self.signatures_file_lock = SimpleFileLock(path)  # lock file to prevent concurrency issues
+        self.signatures_file_lock = self.signatures_file_lock or SimpleFileLock(path)  # lock file to prevent concurrency issues
         self.signatures_file_lock.aquire()  # try to aquire it within the next 10s
 
         if sync and os.path.exists(path):

From 9b5bd6de777e57d48af26f5a26d04f86e8690c93 Mon Sep 17 00:00:00 2001
From: Joran Honig <joran.honig@gmail.com>
Date: Sun, 8 Jul 2018 14:56:24 +0200
Subject: [PATCH 17/18] Use base 16

---
 mythril/laser/ethereum/call.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mythril/laser/ethereum/call.py b/mythril/laser/ethereum/call.py
index 63d09837..aee2f30c 100644
--- a/mythril/laser/ethereum/call.py
+++ b/mythril/laser/ethereum/call.py
@@ -36,7 +36,7 @@ def get_call_parameters(global_state, dynamic_loader, with_value=False):
     callee_account = None
     call_data, call_data_type = get_call_data(global_state, meminstart, meminsz, False)
 
-    if int(callee_address, 16) >= 5 or int(callee_address) == 0:
+    if int(callee_address, 16) >= 5 or int(callee_address, 16) == 0:
         call_data, call_data_type = get_call_data(global_state, meminstart, meminsz)
         callee_account = get_callee_account(global_state, callee_address, dynamic_loader)
 

From deb98df7c5d4bd6467f06073ddb0f545f15154c6 Mon Sep 17 00:00:00 2001
From: Nikhil Parasaram <tommycjniko@gmail.com>
Date: Sun, 8 Jul 2018 23:17:26 +0530
Subject: [PATCH 18/18] return a list for blockhash function

---
 mythril/laser/ethereum/instructions.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mythril/laser/ethereum/instructions.py b/mythril/laser/ethereum/instructions.py
index a7d9521f..949de064 100644
--- a/mythril/laser/ethereum/instructions.py
+++ b/mythril/laser/ethereum/instructions.py
@@ -529,7 +529,7 @@ class Instruction:
             logging.info("error accessing contract storage due to: " + str(e))
             state.stack.append(BitVec("extcodesize_" + str(addr), 256))
             return [global_state]
-        
+
         if code is None:
             state.stack.append(0)
         else:
@@ -555,7 +555,7 @@ class Instruction:
         state = global_state.mstate
         blocknumber = state.stack.pop()
         state.stack.append(BitVec("blockhash_block_" + str(blocknumber), 256))
-        return global_state
+        return [global_state]
 
     @instruction
     def coinbase_(self, global_state):