fix libressl error/refactor some error handling (#3609)

* add libre so I can see the error

* add the libre error needed and refactor error handling a bit

We were historically matching on lib + func + reason, but func is
somewhat unstable so now we match on lib + reason only. Of course, in
this case libressl changed both lib and reason so it wouldn't
have mattered. All error handling from the error queue in
openssl is an illusion

* fix a typo, probably an unneeded branch

* review feedback

* refactor tests to support libressl

insert additional rant about libre here, although admittedly these tests
were assuming stability where openssl itself guarantees none

* better assert, fix flake8

1 files changed, 17 insertions, 2 deletions

diff --git a/src/cryptography/hazmat/bindings/openssl/binding.py b/src/cryptography/hazmat/bindings/openssl/binding.py
index 6b3d50c4..d00fc794 100644
--- a/src/cryptography/hazmat/bindings/openssl/binding.py
+++ b/src/cryptography/hazmat/bindings/openssl/binding.py
@@ -8,17 +8,32 @@ import collections
 import threading
 import types
 
+from cryptography import utils
 from cryptography.exceptions import InternalError
 from cryptography.hazmat.bindings._openssl import ffi, lib
 from cryptography.hazmat.bindings.openssl._conditional import CONDITIONAL_NAMES
 
-_OpenSSLError = collections.namedtuple("_OpenSSLError",
-                                       ["code", "lib", "func", "reason"])
 _OpenSSLErrorWithText = collections.namedtuple(
     "_OpenSSLErrorWithText", ["code", "lib", "func", "reason", "reason_text"]
 )
 
 
+class _OpenSSLError(object):
+    def __init__(self, code, lib, func, reason):
+        self._code = code
+        self._lib = lib
+        self._func = func
+        self._reason = reason
+
+    def _lib_reason_match(self, lib, reason):
+        return lib == self.lib and reason == self.reason
+
+    code = utils.read_only_property("_code")
+    lib = utils.read_only_property("_lib")
+    func = utils.read_only_property("_func")
+    reason = utils.read_only_property("_reason")
+
+
 def _consume_errors(lib):
     errors = []
     while True: