add example to show how to get DNSNames from SAN extension
diff --git a/docs/x509.rst b/docs/x509.rst
index 5f36a92..a8beb20 100644
--- a/docs/x509.rst
+++ b/docs/x509.rst
@@ -50,6 +50,42 @@
-----END CERTIFICATE-----
""".strip()
+ cryptography_cert_pem = b"""
+ -----BEGIN CERTIFICATE-----
+ MIIFvTCCBKWgAwIBAgICPyAwDQYJKoZIhvcNAQELBQAwRzELMAkGA1UEBhMCVVMx
+ FjAUBgNVBAoTDUdlb1RydXN0IEluYy4xIDAeBgNVBAMTF1JhcGlkU1NMIFNIQTI1
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+ GVI9+0lAFwxOUnOnwsoI40iOoxjLMGB+CgFLKCGUcWxP
+ -----END CERTIFICATE-----
+ """.strip()
+
X.509 is an ITU-T standard for a `public key infrastructure`_. X.509v3 is
defined in :rfc:`5280` (which obsoletes :rfc:`2459` and :rfc:`3280`). X.509
certificates are commonly used in protocols like `TLS`_.
@@ -718,6 +754,17 @@
:returns: A list of values extracted from the matched general names.
+ .. doctest::
+
+ >>> from cryptography import x509
+ >>> from cryptography.hazmat.backends import default_backend
+ >>> from cryptography.hazmat.primitives import hashes
+ >>> cert = x509.load_pem_x509_certificate(cryptography_cert_pem, default_backend())
+ >>> ext = cert.extensions.get_extension_for_oid(x509.OID_SUBJECT_ALTERNATIVE_NAME)
+ >>> san = ext.value
+ >>> san.get_values_for_type(x509.DNSName)
+ [u'www.cryptography.io', u'cryptography.io']
+
Object Identifiers
~~~~~~~~~~~~~~~~~~