improve the messages from openssl InternalError

1 files changed, 14 insertions, 5 deletions

diff --git a/src/cryptography/hazmat/bindings/openssl/binding.py b/src/cryptography/hazmat/bindings/openssl/binding.py
index b2215de3..d8fd74db 100644
--- a/src/cryptography/hazmat/bindings/openssl/binding.py
+++ b/src/cryptography/hazmat/bindings/openssl/binding.py
@@ -15,8 +15,9 @@ 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"])
+_OpenSSLError = collections.namedtuple(
+    "_OpenSSLError", ["code", "lib", "func", "reason", "reason_text"]
+)
 
 
 def _consume_errors(lib):
@@ -29,8 +30,12 @@ def _consume_errors(lib):
         err_lib = lib.ERR_GET_LIB(code)
         err_func = lib.ERR_GET_FUNC(code)
         err_reason = lib.ERR_GET_REASON(code)
+        err_text_reason = ffi.string(lib.ERR_error_string(code, ffi.NULL))
+
+        errors.append(
+            _OpenSSLError(code, err_lib, err_func, err_reason, err_text_reason)
+        )
 
-        errors.append(_OpenSSLError(code, err_lib, err_func, err_reason))
     return errors
 
 
@@ -38,8 +43,12 @@ def _openssl_assert(lib, ok):
     if not ok:
         errors = _consume_errors(lib)
         raise InternalError(
-            "Unknown OpenSSL error. Please file an issue at https://github.com"
-            "/pyca/cryptography/issues with information on how to reproduce "
+            "Unknown OpenSSL error. This error is commonly encountered when "
+            "another library is not cleaning up the OpenSSL error stack. If "
+            "you are using cryptography with another Python library that "
+            "uses OpenSSL try disabling it before reporting a bug. Otherwise "
+            "iplease file an issue at https://github.com/pyca/cryptography/"
+            "issues with information on how to reproduce "
             "this. ({0!r})".format(errors),
             errors
         )