Source Code for Module wsgitools.authentication

  1  __all__ = [] 
  2   
  3 -class AuthenticationRequired(Exception): 
  4      """ 
  5      Internal Exception class that is thrown inside L{AuthenticationMiddleware}, 
  6      but not visible to other code. 
  7      """ 
  8   
  9 -class ProtocolViolation(AuthenticationRequired): 
 10      pass 
 11   
 12 -class AuthenticationMiddleware(object): 
 13      """Base class for HTTP authorization schemes. 
 14   
 15      @cvar authorization_method: the implemented Authorization method. It will 
 16          be verified against Authorization headers. Subclasses must define this 
 17          attribute. 
 18      @type authorization_method: str 
 19      """ 
 20      authorization_method = None 
 21 -    def __init__(self, app): 
 22          """ 
 23          @param app: is a WSGI application. 
 24          """ 
 25          assert self.authorization_method is not None 
 26          self.app = app 
 27   
 28 -    def authenticate(self, auth, environ): 
 29          """Try to authenticate a request. The Authorization header is examined 
 30          and checked agains the L{authorization_method} before being passed to 
 31          this method. This method must either raise an AuthenticationRequired 
 32          instance or return a dictionary explaining what was successfully 
 33          authenticated. 
 34   
 35          @type auth: str 
 36          @param auth: is the part of the Authorization header after the method 
 37          @type environ: {str: object} 
 38          @param environ: is the environment passed with a WSGI request 
 39          @rtype: {str: object} 
 40          @returns: a dictionary that provides a key "user" listing the 
 41              authenticated username as a string. It may also provide the key 
 42              "outheaders" with a [(str, str)] value to extend the response 
 43              headers. 
 44          @raises AuthenticationRequired: if the authentication was unsuccessful 
 45          """ 
 46          raise NotImplementedError 
 47   
 48 -    def __call__(self, environ, start_response): 
 49          """wsgi interface 
 50   
 51          @type environ: {str: object} 
 52          """ 
 53          assert isinstance(environ, dict) 
 54          try: 
 55              try: 
 56                  auth = environ["HTTP_AUTHORIZATION"] 
 57              except KeyError: 
 58                  raise AuthenticationRequired("no Authorization header found") 
 59              try: 
 60                  method, rest = auth.split(' ', 1) 
 61              except ValueError: 
 62                  method, rest = auth, "" 
 63              if method.lower() != self.authorization_method: 
 64                  raise AuthenticationRequired( 
 65                      "authorization method not implemented: %r" % method) 
 66              result = self.authenticate(rest, environ) 
 67          except AuthenticationRequired as exc: 
 68              return self.authorization_required(environ, start_response, exc) 
 69          assert isinstance(result, dict) 
 70          assert "user" in result 
 71          environ["REMOTE_USER"] = result["user"] 
 72          if "outheaders" in result: 
 73              def modified_start_response(status, headers, exc_info=None): 
 74                  assert isinstance(headers, list) 
 75                  headers.extend(result["outheaders"]) 
 76                  return start_response(status, headers, exc_info) 
 77          else: 
 78              modified_start_response = start_response 
 79          return self.app(environ, modified_start_response) 
 80   
 81 -    def www_authenticate(self, exception): 
 82          """Generates a WWW-Authenticate header. Subclasses must implement this 
 83          method. 
 84   
 85          @type exception: L{AuthenticationRequired} 
 86          @param exception: reason for generating the header 
 87          @rtype: (str, str) 
 88          @returns: the header as (part_before_colon, part_after_colon) 
 89          """ 
 90          raise NotImplementedError 
 91   
 92 -    def authorization_required(self, environ, start_response, exception): 
 93          """Generate an error page after failed authentication. Apart from the 
 94          exception parameter, this method behaves like a WSGI application. 
 95   
 96          @type exception: L{AuthenticationRequired} 
 97          @param exception: reason for the authentication failure 
 98          """ 
 99          status = "401 Authorization required" 
100          html = b"<html><head><title>401 Authorization required</title></head>" \ 
101                 b"<body><h1>401 Authorization required</h1></body></html>" 
102          headers = [("Content-Type", "text/html"), 
103                     self.www_authenticate(exception), 
104                     ("Content-Length", str(len(html)))] 
105          start_response(status, headers) 
106          if environ["REQUEST_METHOD"].upper() == "HEAD": 
107              return [] 
108          return [html] 
109