Add GeneralName and SubjectAlternativeName classes
diff --git a/docs/x509.rst b/docs/x509.rst
index 19f7c40..b4ff748 100644
--- a/docs/x509.rst
+++ b/docs/x509.rst
@@ -399,6 +399,80 @@
The dotted string value of the OID (e.g. ``"2.5.4.3"``)
+.. _general_name_classes:
+
+General Name Classes
+~~~~~~~~~~~~~~~~~~~~
+
+.. class:: GeneralName
+
+ .. versionadded:: 0.9
+
+ This is the generic interface that all the following classes are registered
+ against.
+
+.. class:: RFC822Name
+
+ .. versionadded:: 0.9
+
+ This corresponds to an email address. For example, ``user@example.com``.
+
+ .. attribute:: value
+
+ :type: :term:`text`
+
+.. class:: DNSName
+
+ .. versionadded:: 0.9
+
+ This corresponds to a domain name. For example, ``cryptography.io``.
+
+ .. attribute:: value
+
+ :type: :term:`text`
+
+.. class:: DirectoryName
+
+ .. versionadded:: 0.9
+
+ This corresponds to a directory name.
+
+ .. attribute:: value
+
+ :type: :class:`Name`
+
+.. class:: UniformResourceIdentifier
+
+ .. versionadded:: 0.9
+
+ This corresponds to a uniform resource identifier. For example,
+ ``https://cryptography.io``.
+
+ .. attribute:: value
+
+ :type: :term:`text`
+
+.. class:: IPAddress
+
+ .. versionadded:: 0.9
+
+ This corresponds to an IP address.
+
+ .. attribute:: value
+
+ :type: :class:`~ipaddress.IPv4Address` or
+ :class:`~ipaddress.IPv6Address`.
+
+.. class:: RegisteredID
+
+ .. versionadded:: 0.9
+
+ This corresponds to a registered ID.
+
+ .. attribute:: value
+
+ :type: :class:`ObjectIdentifier`
+
X.509 Extensions
~~~~~~~~~~~~~~~~
@@ -591,6 +665,22 @@
The binary value of the identifier.
+.. class:: SubjectAlternativeName
+
+ .. versionadded:: 0.9
+
+ Subject alternative name is an X.509 extension that provides a list of
+ :ref:`general name <general_name_classes>` instances that provide a set
+ of identities for which the certificate is valid. The object is iterable to
+ get every element.
+
+ .. method:: get_values_for_type(type)
+
+ :param type: A :class:`GeneralName` provider. This is one of the
+ :ref:`general name classes <general_name_classes>`.
+
+ :returns: A list of values extracted from the matched general names.
+
Object Identifiers
~~~~~~~~~~~~~~~~~~