create AuthenticationContext to consolidate auth logic

atst/domain/authnid/__init__.py

@@ -0,0 +1,62 @@
+from atst.domain.exceptions import UnauthenticatedError, NotFoundError
+from atst.domain.users import Users
+from .utils import parse_sdn, email_from_certificate
+
+
+class AuthenticationContext():
+
+    def __init__(self, crl_validator, auth_status, sdn, cert):
+        if None in locals().values():
+            raise UnauthenticatedError("Missing required authentication context components")
+
+        self.crl_validator = crl_validator
+        self.auth_status = auth_status
+        self.sdn = sdn
+        self.cert = cert.encode()
+        self._parsed_sdn = None
+
+
+    def authenticate(self):
+        if not self.auth_status == "SUCCESS":
+            raise UnauthenticatedError("SSL/TLS client authentication failed")
+
+        elif not self._crl_check():
+            raise UnauthenticatedError("Client certificate failed CRL check")
+
+        return True
+
+
+    def get_user(self):
+        try:
+            return Users.get_by_dod_id(self.parsed_sdn["dod_id"])
+
+        except NotFoundError:
+            email = self._get_user_email()
+            return Users.create(**{"email": email, **self.parsed_sdn})
+
+    def _get_user_email(self):
+        try:
+            return email_from_certificate(self.cert)
+
+        # this just means it is not an email certificate; we might choose to
+        # log in that case
+        except ValueError:
+            return None
+
+    def _crl_check(self):
+        if self.cert:
+            result = self.crl_validator.validate(self.cert)
+            return result
+
+        else:
+            return False
+
+    @property
+    def parsed_sdn(self):
+        if not self._parsed_sdn:
+            try:
+                self._parsed_sdn = parse_sdn(self.sdn)
+            except ValueError as exc:
+                raise UnauthenticatedError(str(exc))
+
+        return self._parsed_sdn

atst/domain/exceptions.py

@@ -30,3 +30,7 @@ class UnauthenticatedError(Exception):
     @property
     def message(self):
         return str(self)
+
+
+class CRLValidationError(Exception):
+    pass