Move version check to netlib, unit test it.

netlib/version_check.py

@@ -0,0 +1,49 @@
+from __future__ import print_function, absolute_import
+import sys
+import inspect
+import os.path
+
+import OpenSSL
+from . import version
+
+PYOPENSSL_MIN_VERSION = (0, 15)
+
+
+def version_check(
+        mitmproxy_version,
+        pyopenssl_min_version=PYOPENSSL_MIN_VERSION,
+        fp=sys.stderr):
+    """
+    Having installed a wrong version of pyOpenSSL or netlib is unfortunately a
+    very common source of error. Check before every start that both versions
+    are somewhat okay.
+    """
+    # We don't introduce backward-incompatible changes in patch versions. Only
+    # consider major and minor version.
+    if version.IVERSION[:2] != mitmproxy_version[:2]:
+        print(
+            "You are using mitmproxy %s with netlib %s. "
+            "Most likely, that won't work - please upgrade!" % (
+                mitmproxy_version, version.VERSION
+            ),
+            file=fp
+        )
+        sys.exit(1)
+    v = tuple([int(x) for x in OpenSSL.__version__.split(".")][:2])
+    if v < pyopenssl_min_version:
+        print(
+            "You are using an outdated version of pyOpenSSL:"
+            " mitmproxy requires pyOpenSSL %x or greater." %
+            pyopenssl_min_version,
+            file=fp
+        )
+        # Some users apparently have multiple versions of pyOpenSSL installed.
+        # Report which one we got.
+        pyopenssl_path = os.path.dirname(inspect.getfile(OpenSSL))
+        print(
+            "Your pyOpenSSL %s installation is located at %s" % (
+                OpenSSL.__version__, pyopenssl_path
+            ),
+            file=fp
+        )
+        sys.exit(1)

test/test_version_check.py

@@ -0,0 +1,22 @@
+import cStringIO
+import mock
+from netlib import version_check, version
+
+
+@mock.patch("sys.exit")
+def test_version_check(sexit):
+    fp = cStringIO.StringIO()
+    version_check.version_check(version.IVERSION, fp=fp)
+    assert not sexit.called
+
+    b = (version.IVERSION[0] - 1, version.IVERSION[1])
+    version_check.version_check(b, fp=fp)
+    assert sexit.called
+
+    sexit.reset_mock()
+    version_check.version_check(
+        version.IVERSION,
+        pyopenssl_min_version=(9999,),
+        fp=fp
+    )
+    assert sexit.called