libs/openid/yadis/xrires.py

   1 # -*- test-case-name: openid.test.test_xrires -*-
   2 """XRI resolution.
   3 """
   4
   5 from urllib import urlencode
   6 from openid import fetchers
   7 from openid.yadis import etxrd
   8 from openid.yadis.xri import toURINormal
   9 from openid.yadis.services import iterServices
  10
  11 DEFAULT_PROXY = 'http://proxy.xri.net/'
  12
  13 class ProxyResolver(object):
  14     """Python interface to a remote XRI proxy resolver.
  15     """
  16     def __init__(self, proxy_url=DEFAULT_PROXY):
  17         self.proxy_url = proxy_url
  18
  19
  20     def queryURL(self, xri, service_type=None):
  21         """Build a URL to query the proxy resolver.
  22
  23         @param xri: An XRI to resolve.
  24         @type xri: unicode
  25
  26         @param service_type: The service type to resolve, if you desire
  27             service endpoint selection.  A service type is a URI.
  28         @type service_type: str
  29
  30         @returns: a URL
  31         @returntype: str
  32         """
  33         # Trim off the xri:// prefix.  The proxy resolver didn't accept it
  34         # when this code was written, but that may (or may not) change for
  35         # XRI Resolution 2.0 Working Draft 11.
  36         qxri = toURINormal(xri)[6:]
  37         hxri = self.proxy_url + qxri
  38         args = {
  39             # XXX: If the proxy resolver will ensure that it doesn't return
  40             # bogus CanonicalIDs (as per Steve's message of 15 Aug 2006
  41             # 11:13:42), then we could ask for application/xrd+xml instead,
  42             # which would give us a bit less to process.
  43             '_xrd_r': 'application/xrds+xml',
  44             }
  45         if service_type:
  46             args['_xrd_t'] = service_type
  47         else:
  48             # Don't perform service endpoint selection.
  49             args['_xrd_r'] += ';sep=false'
  50         query = _appendArgs(hxri, args)
  51         return query
  52
  53
  54     def query(self, xri, service_types):
  55         """Resolve some services for an XRI.
  56
  57         Note: I don't implement any service endpoint selection beyond what
  58         the resolver I'm querying does, so the Services I return may well
  59         include Services that were not of the types you asked for.
  60
  61         May raise fetchers.HTTPFetchingError or L{etxrd.XRDSError} if
  62         the fetching or parsing don't go so well.
  63
  64         @param xri: An XRI to resolve.
  65         @type xri: unicode
  66
  67         @param service_types: A list of services types to query for.  Service
  68             types are URIs.
  69         @type service_types: list of str
  70
  71         @returns: tuple of (CanonicalID, Service elements)
  72         @returntype: (unicode, list of C{ElementTree.Element}s)
  73         """
  74         # FIXME: No test coverage!
  75         services = []
  76         # Make a seperate request to the proxy resolver for each service
  77         # type, as, if it is following Refs, it could return a different
  78         # XRDS for each.
  79
  80         canonicalID = None
  81
  82         for service_type in service_types:
  83             url = self.queryURL(xri, service_type)
  84             response = fetchers.fetch(url)
  85             if response.status not in (200, 206):
  86                 # XXX: sucks to fail silently.
  87                 # print "response not OK:", response
  88                 continue
  89             et = etxrd.parseXRDS(response.body)
  90             canonicalID = etxrd.getCanonicalID(xri, et)
  91             some_services = list(iterServices(et))
  92             services.extend(some_services)
  93         # TODO:
  94         #  * If we do get hits for multiple service_types, we're almost
  95         #    certainly going to have duplicated service entries and
  96         #    broken priority ordering.
  97         return canonicalID, services
  98
  99
 100 def _appendArgs(url, args):
 101     """Append some arguments to an HTTP query.
 102     """
 103     # to be merged with oidutil.appendArgs when we combine the projects.
 104     if hasattr(args, 'items'):
 105         args = args.items()
 106         args.sort()
 107
 108     if len(args) == 0:
 109         return url
 110
 111     # According to XRI Resolution section "QXRI query parameters":
 112     #
 113     # """If the original QXRI had a null query component (only a leading
 114     #    question mark), or a query component consisting of only question
 115     #    marks, one additional leading question mark MUST be added when
 116     #    adding any XRI resolution parameters."""
 117
 118     if '?' in url.rstrip('?'):
 119         sep = '&'
 120     else:
 121         sep = '?'
 122
 123     return '%s%s%s' % (url, sep, urlencode(args))