Getting to actually knowing the client email address

oauthproxy.py

@@ -0,0 +1,102 @@
+#!/usr/bin/python3
+
+import argparse
+from oauth2client import client
+from urllib import parse
+import requests
+from http import server
+import socket
+
+
+parser = argparse.ArgumentParser(description='oauthproxy')
+parser.add_argument(
+    '--api-key',
+    dest='api_key',
+    action='store',
+    required=True)
+parser.add_argument(
+    '--listen-host',
+    dest='listen_host',
+    action='store',
+    default='::')
+parser.add_argument(
+    '--listen-port',
+    dest='listen_port',
+    type=int,
+    action='store',
+    default=443)
+FLAGS = parser.parse_args()
+
+
+class HTTPServer6(server.HTTPServer):
+  address_family = socket.AF_INET6
+
+
+class OAuthProxy(object):
+
+  def __init__(self, listen_host, listen_port, api_key):
+    self._api_key = api_key
+
+    HANDLERS = {
+      '/': self._ServeRedirect,
+      '/oauth2callback': self._OAuth2Callback,
+    }
+
+    class RequestHandler(server.BaseHTTPRequestHandler):
+      def do_GET(self):
+        self.parsed_url = parse.urlparse(self.path)
+        try:
+          HANDLERS[self.parsed_url.path](self)
+        except KeyError:
+          self.send_response(404)
+          self.end_headers()
+
+    self._httpd = HTTPServer6((listen_host, listen_port), RequestHandler)
+
+  def Serve(self):
+    self._httpd.serve_forever()
+
+  def _GetFlow(self, req):
+    return_url = ''.join([
+      'http://',
+      req.headers['Host'],
+      '/oauth2callback',
+    ])
+    return client.flow_from_clientsecrets(
+        'client_secrets.json',
+        scope='https://www.googleapis.com/auth/userinfo.email',
+        redirect_uri=return_url)
+
+  def _ServeRedirect(self, req):
+    req.send_response(302)
+    req.send_header('Location', self._GetFlow(req).step1_get_authorize_url())
+    req.end_headers()
+
+  def _OAuth2Callback(self, req):
+    qs = parse.parse_qs(req.parsed_url.query)
+    credentials = self._GetFlow(req).step2_exchange(qs['code'][0])
+    result = requests.get(
+        'https://www.googleapis.com/plus/v1/people/me?%s' % parse.urlencode({
+          'key': self._api_key,
+          'access_token': credentials.access_token,
+        }))
+    emails = [
+      x['value']
+      for x in result.json()['emails']
+      if x['type'] == 'account'
+    ]
+    req.send_response(200)
+    req.end_headers()
+    req.wfile.write(emails[0].encode('utf8'))
+
+
+def main():
+  server = OAuthProxy(
+      FLAGS.listen_host,
+      FLAGS.listen_port,
+      FLAGS.api_key)
+  server.Serve()
+
+
+if __name__ == '__main__':
+  main()