1 files changed, 80 insertions, 0 deletions
diff --git a/wsgitools/authentication.py b/wsgitools/authentication.py
new file mode 100644
index 0000000..a36b794
--- /dev/null
+++ b/wsgitools/authentication.py
@@ -0,0 +1,80 @@
+__all__ = []
+
+class AuthenticationRequired(Exception):
+    """
+    Internal Exception class that is thrown inside L{AuthenticationMiddleware},
+    but not visible to other code.
+    """
+
+class ProtocolViolation(AuthenticationRequired):
+    pass
+
+class AuthenticationMiddleware:
+    """Base class for HTTP authorization schemes.
+
+    @cvar authorization_required: the implemented Authorization method. It will
+        be verified against Authorization headers. Subclasses must define this
+        attribute.
+    @type authorization_required: str
+    """
+    authorization_method = None
+    def __init__(self, app):
+        """
+        @param app: is a WSGI application.
+        """
+        assert self.authorization_method is not None
+        self.app = app
+
+    def authenticate(self, auth, environ, start_response):
+        """
+        @type auth: str
+        @param auth: is the part of the Authorization header after the method
+        """
+        raise NotImplementedError
+
+    def __call__(self, environ, start_response):
+        assert isinstance(environ, dict)
+        try:
+            try:
+                auth = environ["HTTP_AUTHORIZATION"]
+            except KeyError:
+                raise AuthenticationRequired("no Authorization header found")
+            try:
+                method, rest = auth.split(' ', 1)
+            except ValueError:
+                method, rest = auth, ""
+            if method.lower() != self.authorization_method:
+                raise AuthenticationRequired(
+                    "authorization method not implemented: %r" % method)
+            return self.authenticate(rest, environ, start_response)
+        except AuthenticationRequired, exc:
+            return self.authorization_required(environ, start_response, exc)
+
+    def www_authenticate(self, exception):
+        """Generates a WWW-Authenticate header. Subclasses must implement this
+        method.
+
+        @type exception: AuthenticationRequired
+        @param exception: reason for generating the header
+        @rtype: (str, str)
+        @returns: the header as (part_before_colon, part_after_colon)
+        """
+        raise NotImplementedError
+
+    def authorization_required(self, environ, start_response, exception):
+        """Generate an error page after failed authentication. Apart from the
+        exception parameter, this method behaves like a WSGI application.
+
+        @type exception: AuthenticationRequired
+        @param exception: reason for the authentication failure
+        """
+        status = "401 Authorization required"
+        html = "<html><head><title>401 Authorization required</title></head>" \
+               "<body><h1>401 Authorization required</h1></body></html>"
+        headers = [("Content-Type", "text/html"),
+                   self.www_authenticate(exception),
+                   ("Content-Length", str(len(html)))]
+        start_response(status, headers)
+        if environ["REQUEST_METHOD"].upper() == "HEAD":
+            return []
+        return [html]