Support Pragmas (#1591)

* Support Pragmas

* Fix MarkUpSafe

mythril/ethereum/util.py

@@ -10,13 +10,13 @@ import solc
 
 from pathlib import Path
 from subprocess import PIPE, Popen
+from typing import Optional
 
 from json.decoder import JSONDecodeError
 from mythril.exceptions import CompilerError
-from semantic_version import Version
+from semantic_version import Version, NpmSpec
 
-if sys.version_info[1] >= 6:
-    import solcx
+import solcx
 
 log = logging.getLogger(__name__)
 
@@ -123,31 +123,39 @@ def solc_exists(version):
     """
 
     default_binary = "/usr/bin/solc"
-    if sys.version_info[1] >= 6:
-        if platform.system() == "Darwin":
-            solcx.import_installed_solc()
-        solcx.install_solc("v" + version)
-        solcx.set_solc_version("v" + version)
-        solc_binary = solcx.install.get_executable()
-        return solc_binary
-    elif Version("0.4.2") <= Version(version) <= Version("0.4.25"):
-        if not solc.main.is_solc_available():
-            solc.install_solc("v" + version)
-            solc_binary = solc.install.get_executable_path("v" + version)
-            return solc_binary
-        else:
-            solc_binaries = [
-                os.path.join(
-                    os.environ.get("HOME", str(Path.home())),
-                    ".py-solc/solc-v" + version,
-                    "bin/solc",
-                )  # py-solc setup
-            ]
-            for solc_path in solc_binaries:
-                if os.path.exists(solc_path):
-                    return solc_path
-    elif os.path.exists(default_binary):
-        return default_binary
+    if platform.system() == "Darwin":
+        solcx.import_installed_solc()
+    solcx.install_solc("v" + version)
+    solcx.set_solc_version("v" + version)
+    solc_binary = solcx.install.get_executable()
+    return solc_binary
 
-    else:
+
+all_versions = solcx.get_installable_solc_versions()
+
+
+def extract_version(file: str) -> Optional[str]:
+    version_line = None
+    for line in file.split("\n"):
+        if "pragma solidity" not in line:
+            continue
+        version_line = line
+        break
+    if version_line is None:
         return None
+    if version_line[-1] == ";":
+        version_line = version_line[:-1]
+    version_line = version_line.replace("pragma solidity", "").lstrip()
+    version_constraint = NpmSpec(version_line)
+    for version in all_versions:
+        if version in version_constraint:
+            return str(version)
+    return None
+
+
+def extract_binary(file: str) -> str:
+    with open(file) as f:
+        version = extract_version(f.read())
+    if version is None:
+        return os.environ.get("SOLC") or "solc"
+    return solc_exists(version)

mythril/mythril/mythril_disassembler.py

@@ -43,7 +43,7 @@ class MythrilDisassembler:
         self.contracts = []  # type: List[EVMContract]
 
     @staticmethod
-    def _init_solc_binary(version: str) -> str:
+    def _init_solc_binary(version: str) -> Optional[str]:
         """
         Only proper versions are supported. No nightlies, commits etc (such as available in remix).
         :param version: Version of the solc binary required
@@ -51,7 +51,7 @@ class MythrilDisassembler:
         """
 
         if not version:
-            return os.environ.get("SOLC") or "solc"
+            return None
 
         # tried converting input to semver, seemed not necessary so just slicing for now
         try:
@@ -60,7 +60,6 @@ class MythrilDisassembler:
             main_version = ""  # allow missing solc will download instead
         main_version_number = re.match(r"\d+.\d+.\d+", main_version)
 
-        # In case instead of just the version number, --solv v0.x.x is used
         if version.startswith("v"):
             version = version[1:]
 
@@ -70,18 +69,9 @@ class MythrilDisassembler:
         else:
             solc_binary = util.solc_exists(version)
             if solc_binary is None:
-                if sys.version_info[1] >= 6:
-                    raise CriticalError(
-                        "The version of solc that is needed cannot be installed automatically"
-                    )
-                elif sys.version_info[1] == 5:
-                    raise CriticalError(
-                        "Py-Solc doesn't support 0.5.*+. You can switch to python 3.6 which uses solcx."
-                    )
-                else:
-                    raise CriticalError(
-                        "There was an error when trying to install the specified solc version"
-                    )
+                raise CriticalError(
+                    "The version of solc that is needed cannot be installed automatically"
+                )
             else:
                 log.info("Setting the compiler to %s", solc_binary)
 
@@ -171,12 +161,12 @@ class MythrilDisassembler:
                 contract_name = None
 
             file = os.path.expanduser(file)
-
+            solc_binary = self.solc_binary or util.extract_binary(file)
             try:
                 # import signatures from solidity source
                 self.sigs.import_solidity_file(
                     file,
-                    solc_binary=self.solc_binary,
+                    solc_binary=solc_binary,
                     solc_settings_json=self.solc_settings_json,
                 )
                 if contract_name is not None:
@@ -184,7 +174,7 @@ class MythrilDisassembler:
                         input_file=file,
                         name=contract_name,
                         solc_settings_json=self.solc_settings_json,
-                        solc_binary=self.solc_binary,
+                        solc_binary=solc_binary,
                     )
                     self.contracts.append(contract)
                     contracts.append(contract)
@@ -192,7 +182,7 @@ class MythrilDisassembler:
                     for contract in get_contracts_from_file(
                         input_file=file,
                         solc_settings_json=self.solc_settings_json,
-                        solc_binary=self.solc_binary,
+                        solc_binary=solc_binary,
                     ):
                         self.contracts.append(contract)
                         contracts.append(contract)

requirements.txt

@@ -15,6 +15,7 @@ eth-rlp<0.3.0,>=0.1.0
 eth-typing<3.0.0,>=2.1.0
 eth-utils<2
 jinja2>=2.9
+MarkupSafe<2.1.0
 mock
 persistent>=4.2.0
 py-flags

tests/util_tests.py

@@ -0,0 +1,56 @@
+import pytest
+
+from mythril.ethereum.util import extract_version
+
+
+test_data = (
+    ("pragma solidity 0.5.0\n", ["0.5.0"]),
+    ("pragma solidity ^0.4.26\n", ["0.4.26"]),
+    ("pragma solidity ^0.6.3;\n", [f"0.6.{x}" for x in range(3, 13)]),
+    (
+        """pragma solidity >=0.4.0 <0.6.0;
+        contract SimpleStorage {
+            uint storedData;
+            function set(uint x) public {
+                storedData = x;
+            }
+            function get() public view returns (uint) {
+                return storedData;
+            }
+        }""",
+        [f"0.4.{x}" for x in range(11, 27)] + [f"0.5.{x}" for x in range(0, 18)],
+    ),
+    (
+        """
+        pragma solidity >=0.4.0 <0.6.0
+        ;contract SimpleStorage {
+            uint storedData;
+            function set(uint x) public {
+                storedData = x;
+            }
+            function get() public view returns (uint) {
+                return storedData;
+            }
+        }""",
+        [f"0.4.{x}" for x in range(11, 27)] + [f"0.5.{x}" for x in range(0, 18)],
+    ),
+    (
+        """
+        pragma solidity >=0.4.0 <0.6.0
+        ;contract SimpleStorage {
+            uint storedData;
+            function set(uint x) public {
+                storedData = x;
+            }
+            function get() public view returns (uint) {
+                return storedData;
+            }
+        }""",
+        [f"0.4.{x}" for x in range(11, 27)] + [f"0.5.{x}" for x in range(0, 18)],
+    ),
+)
+
+
+@pytest.mark.parametrize("input_,output", test_data)
+def test_sar(input_, output):
+    assert extract_version(input_) in output