SAML20 example code

[Simon Josefsson]

To illustrate how the SAML20 mechanism in the 1.7.x branch works, I have
written two examples:: one dummy XMPP client and one dummy XMPP server.
Of course, they don't implement XMPP, nor SAML, but from a SASL point of
view they should be complete.

The example code is available here:
http://git.savannah.gnu.org/gitweb/?p=gsasl.git;a=blob;f=examples/client-xmpp-saml20.c;h=b1a016a2efaaf786bbfdfc07798a73c678fdd013;hb=saml
http://git.savannah.gnu.org/gitweb/?p=gsasl.git;a=blob;f=examples/server-xmpp-saml20.c;h=5fd1e74ee28f56dd0177201eeb7ea9d80334e3d4;hb=saml

Below I'll walk through how they work, cut'n'pasting command line
output.  Lines prefixed with W1 indicate something running in the first
window (the client) and lines prefixed with W2 indicate something
running the second window (the server).

First start the client:

W1: address@hidden:~/src/gsasl/examples$ ./client-xmpp-saml20 
W1: Unknown property 2!  Don't worry.
W1: <auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' 
mechanism='SAML20'>biwsaHR0cHM6Ly9zYW1sLmV4YW1wbGUub3JnLw==</auth>

Now I need to start the server:

W2: address@hidden:~/src/gsasl/examples$ ./server-xmpp-saml20
W2: 

It is waiting for input.  Cut'n'paste the final line from the client
into the second window, like this:

W2: <auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' 
mechanism='SAML20'>biwsaHR0cHM6Ly9zYW1sLmV4YW1wbGUub3JnLw==</auth>
W2: parsed: 'biwsaHR0cHM6Ly9zYW1sLmV4YW1wbGUub3JnLw=='
W2: server got identity: https://saml.example.org/
W2: <challenge 
xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>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</challenge>

As you can see, it could parse the XML correctly, the callback
understood the identity URL, and returned a SAML redirect blob.  Now
you need to cut'n'paste the final line back to the client:

W1: <challenge 
xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>aHR0cHM6Ly9zYW1sLmV4YW1wbGUub3JnL1NBTUwvQnJvd3Nlcj9TQU1MUmVxdWVzdD1QSE5oYld4d09rRjFkR2h1VW1WeGRXVnpkQ0I0Yld4dWN6cHpZVzFzY0QwaWRYSnVPbTloYzJsek9tNWhiV1Z6T25Sak9sTkJUVXc2TWk0d09uQnliM1J2WTI5c0lnMEtJQ0FnSUVsRVBTSmZZbVZqTkRJMFptRTFNVEF6TkRJNE9UQTVZVE13Wm1ZeFpUTXhNVFk0TXpJM1pqYzVORGMwT1RnMElpQldaWEp6YVc5dVBTSXlMakFpRFFvZ0lDQWdTWE56ZFdWSmJuTjBZVzUwUFNJeU1EQTNMVEV5TFRFd1ZERXhPak01T2pNMFdpSWdSbTl5WTJWQmRYUm9iajBpWm1Gc2MyVWlEUW9nSUNBZ1NYTlFZWE56YVhabFBTSm1ZV3h6WlNJTkNpQWdJQ0JRY205MGIyTnZiRUpwYm1ScGJtYzlJblZ5YmpwdllYTnBjenB1WVcxbGN6cDBZenBUUVUxTU9qSXVNRHBpYVc1a2FXNW5jenBJVkZSUUxWQlBVMVFpRFFvZ0lDQWdRWE56WlhKMGFXOXVRMjl1YzNWdFpYSlRaWEoyYVdObFZWSk1QUTBLSUNBZ0lDQWdJQ0FpYUhSMGNITTZMeTk0YlhCd0xtVjRZVzF3YkdVdVkyOXRMMU5CVFV3dlFYTnpaWEowYVc5dVEyOXVjM1Z0WlhKVFpYSjJhV05sSWo0TkNpQThjMkZ0YkRwSmMzTjFaWElnZUcxc2JuTTZjMkZ0YkQwaWRYSnVPbTloYzJsek9tNWhiV1Z6T25Sak9sTkJUVXc2TWk0d09tRnpjMlZ5ZEdsdmJpSStEUW9nSUNBZ0lHaDBkSEJ6T2k4dmVHMXdjQzVsZUdGdGNHeGxMbU52YlEwS0lEd3ZjMkZ0YkRwSmMzTjFaWEkrRFFvZ1BITmhiV3h3T2s1aGJXVkpSRkJ2YkdsamVTQjRiV3h1Y3pwellXMXNjRDBpZFhKdU9tOWhjMmx6T201aGJXVnpPblJqT2xOQlRVdzZNaTR3T25CeWIzUnZZMjlzSWcwS0lDQWdJQ0JHYjNKdFlYUTlJblZ5YmpwdllYTnBjenB1WVcxbGN6cDBZenBUUVUxTU9qSXVNRHB1WVcxbGFXUXRabTl5YldGME9uQmxjbk5wYzNSbGJuUWlEUW9nSUNBZ0lGTlFUbUZ0WlZGMVlXeHBabWxsY2owaWVHMXdjQzVsZUdGdGNHeGxMbU52YlNJZ1FXeHNiM2REY21WaGRHVTlJblJ5ZFdVaUlDOCtEUW9nUEhOaGJXeHdPbEpsY1hWbGMzUmxaRUYxZEdodVEyOXVkR1Y0ZEEwS0lDQWdJQ0I0Yld4dWN6cHpZVzFzY0QwaWRYSnVPbTloYzJsek9tNWhiV1Z6T25Sak9sTkJUVXc2TWk0d09uQnliM1J2WTI5c0lpQU5DaUFnSUNBZ0lDQWdRMjl0Y0dGeWFYTnZiajBpWlhoaFkzUWlQZzBLSUNBOGMyRnRiRHBCZFhSb2JrTnZiblJsZUhSRGJHRnpjMUpsWmcwS0lDQWdJQ0FnZUcxc2JuTTZjMkZ0YkQwaWRYSnVPbTloYzJsek9tNWhiV1Z6T25Sak9sTkJUVXc2TWk0d09tRnpjMlZ5ZEdsdmJpSStEUW9nSUNBZ0lDQWdJQ0FnSUhWeWJqcHZZWE5wY3pwdVlXMWxjenAwWXpwVFFVMU1Pakl1TURwaFl6cGpiR0Z6YzJWek9sQmhjM04zYjNKa1VISnZkR1ZqZEdWa1ZISmhibk53YjNKMERRb2dJRHd2YzJGdGJEcEJkWFJvYmtOdmJuUmxlSFJEYkdGemMxSmxaajROQ2lBOEwzTmhiV3h3T2xKbGNYVmxjM1JsWkVGMWRHaHVRMjl1ZEdWNGRENGdEUW84TDNOaGJXeHdPa0YxZEdodVVtVnhkV1Z6ZEQ0PQ==</challenge>
W1: parsed: 
'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'
W1: client got redirect URL: 
https://saml.example.org/SAML/Browser?SAMLRequest=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
W1: <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'></response>
W1: If server accepted us, we're done.
W1: address@hidden:~/src/gsasl/examples$ 

The client sent the empty response back to the server, but is otherwise
done with the SASL stuff.  You need to cut'n'paste the XMPP data to the
server, like this:

W2: <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'></response>
W2: parsed: ''
W2: Authorization decision time!
W2: User identity: https://saml.example.org/
W2: Accept user? (y/n) y
W2: <success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
W2: address@hidden:~/src/gsasl/examples$ 

It even prints a nice XMPP <success> tag.  If you press 'n' you should
see this:

W2: <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'></response>
W2: parsed: ''
W2: Authorization decision time!
W2: User identity: https://saml.example.org/
W2: Accept user? (y/n) n
W2: <failure 
xmlns='urn:ietf:params:xml:ns:xmpp-sasl'><temporary-auth-failure/></failure></stream:stream>
W2: Authentication error (31): Error authenticating user
W2: address@hidden:~/src/gsasl/examples$ 

Happy hacking,
/Simon