1 # Thierry Parmentelat -- INRIA
3 # a minimal library for writing "lightweight" SFA clients
7 # this library should probably check for the expiration date of the various
8 # certificates and automatically retrieve fresh ones when expired
12 from datetime import datetime
13 from sfa.util.xrn import Xrn
15 import sfa.util.sfalogging
16 # importing sfa.utils.faults does pull a lot of stuff
17 # OTOH it's imported from Certificate anyways, so..
18 from sfa.util.faults import RecordNotFound
20 from sfa.client.sfaserverproxy import SfaServerProxy
22 # see optimizing dependencies below
23 from sfa.trust.certificate import Keypair, Certificate
24 from sfa.trust.credential import Credential
26 # a helper class to implement the bootstrapping of crypto. material
27 # assuming we are starting from scratch on the client side
28 # what's needed to complete a full slice creation cycle
30 # (*) a local private key
31 # (*) the corresp. public key in the registry
32 # (**) step1: a self-signed certificate
33 # default filename is <hrn>.sscert
34 # (**) step2: a user credential
35 # obtained at the registry with GetSelfCredential
36 # using the self-signed certificate as the SSL cert
37 # default filename is <hrn>.user.cred
38 # (**) step3: a registry-provided certificate (i.e. a GID)
39 # obtained at the registry using Resolve
40 # using the step2 credential as credential
41 # default filename is <hrn>.user.gid
43 # From that point on, the GID is used as the SSL certificate
44 # and the following can be done
46 # (**) retrieve a slice (or authority) credential
47 # obtained at the registry with GetCredential
48 # using the (step2) user-credential as credential
49 # default filename is <hrn>.<type>.cred
50 # (**) retrieve a slice (or authority) GID
51 # obtained at the registry with Resolve
52 # using the (step2) user-credential as credential
53 # default filename is <hrn>.<type>.cred
56 ########## Implementation notes
60 # this implementation is designed as a guideline for
61 # porting to other languages
63 # the decision to go for decorators aims at focusing
64 # on the core of what needs to be done when everything
65 # works fine, and to take caching and error management
68 # for non-pythonic developers, it should be enough to
69 # implement the bulk of this code, namely the _produce methods
70 # and to add caching and error management by whichever means
71 # is available, including inline
73 # (*) self-signed certificates
75 # still with other languages in mind, we've tried to keep the
76 # dependencies to the rest of the code as low as possible
78 # however this still relies on the sfa.trust.certificate module
79 # for the initial generation of a self-signed-certificate that
80 # is associated to the user's ssh-key
81 # (for user-friendliness, and for smooth operations with planetlab,
82 # the usage model is to reuse an existing keypair)
84 # there might be a more portable, i.e. less language-dependant way, to
85 # implement this step by exec'ing the openssl command a known
86 # successful attempt at this approach that worked for Java is
88 # http://nam.ece.upatras.gr/fstoolkit/trac/wiki/JavaSFAClient
92 class SfaClientException (Exception): pass
94 class SfaClientBootstrap:
96 # dir is mandatory but defaults to '.'
97 def __init__ (self, user_hrn, registry_url, dir=None,
98 verbose=False, timeout=None, logger=None):
100 self.registry_url=registry_url
101 if dir is None: dir="."
105 # default for the logger is to use the global sfa logger
107 logger = sfa.util.sfalogging.logger
110 ######################################## *_produce methods
112 # unconditionnally create a self-signed certificate
113 def self_signed_cert_produce (self,output):
114 self.assert_private_key()
115 private_key_filename = self.private_key_filename()
116 keypair=Keypair(filename=private_key_filename)
117 self_signed = Certificate (subject = self.hrn)
118 self_signed.set_pubkey (keypair)
119 self_signed.set_issuer (keypair, self.hrn)
121 self_signed.save_to_file (output)
122 self.logger.debug("SfaClientBootstrap: Created self-signed certificate for %s in %s"%\
127 # unconditionnally retrieve my credential (GetSelfCredential)
128 # we always use the self-signed-cert as the SSL cert
129 def my_credential_produce (self, output):
130 self.assert_self_signed_cert()
131 certificate_filename = self.self_signed_cert_filename()
132 certificate_string = self.plain_read (certificate_filename)
133 self.assert_private_key()
134 registry_proxy = SfaServerProxy (self.registry_url, self.private_key_filename(),
135 certificate_filename)
136 credential_string=registry_proxy.GetSelfCredential (certificate_string, self.hrn, "user")
137 self.plain_write (output, credential_string)
138 self.logger.debug("SfaClientBootstrap: Wrote result of GetSelfCredential in %s"%output)
142 # unconditionnally retrieve my GID - use the general form
143 def my_gid_produce (self,output):
144 return self.gid_produce (output, self.hrn, "user")
146 ### retrieve any credential (GetCredential) unconditionnal form
147 # we always use the GID as the SSL cert
148 def credential_produce (self, output, hrn, type):
150 certificate_filename = self.my_gid_filename()
151 self.assert_private_key()
152 registry_proxy = SfaServerProxy (self.registry_url, self.private_key_filename(),
153 certificate_filename)
154 self.assert_my_credential()
155 my_credential_string = self.my_credential_string()
156 credential_string=registry_proxy.GetCredential (my_credential_string, hrn, type)
157 self.plain_write (output, credential_string)
158 self.logger.debug("SfaClientBootstrap: Wrote result of GetCredential in %s"%output)
161 def slice_credential_produce (self, output, hrn):
162 return self.credential_produce (output, hrn, "slice")
164 def authority_credential_produce (self, output, hrn):
165 return self.credential_produce (output, hrn, "authority")
167 ### retrieve any gid (Resolve) - unconditionnal form
168 # use my GID when available as the SSL cert, otherwise the self-signed
169 def gid_produce (self, output, hrn, type ):
172 certificate_filename = self.my_gid_filename()
174 self.assert_self_signed_cert()
175 certificate_filename = self.self_signed_cert_filename()
177 self.assert_private_key()
178 registry_proxy = SfaServerProxy (self.registry_url, self.private_key_filename(),
179 certificate_filename)
180 credential_string=self.plain_read (self.my_credential())
181 records = registry_proxy.Resolve (hrn, credential_string)
182 records=[record for record in records if record['type']==type]
184 raise RecordNotFound, "hrn %s (%s) unknown to registry %s"%(hrn,type,self.registry_url)
186 self.plain_write (output, record['gid'])
187 self.logger.debug("SfaClientBootstrap: Wrote GID for %s (%s) in %s"% (hrn,type,output))
191 # Returns True if credential file is valid. Otherwise return false.
192 def validate_credential(self, filename):
194 cred = Credential(filename=filename)
195 # check if credential is expires
196 if cred.get_expiration() < datetime.now():
201 #################### public interface
203 # return my_gid, run all missing steps in the bootstrap sequence
204 def bootstrap_my_gid (self):
205 self.self_signed_cert()
209 # once we've bootstrapped we can use this object to issue any other SFA call
211 def server_proxy (self, url):
213 return SfaServerProxy (url, self.private_key_filename(), self.my_gid_filename(),
214 verbose=self.verbose, timeout=self.timeout)
216 # now in some cases the self-signed is enough
217 def server_proxy_simple (self, url):
218 self.assert_self_signed_cert()
219 return SfaServerProxy (url, self.private_key_filename(), self.self_signed_cert_filename(),
220 verbose=self.verbose, timeout=self.timeout)
222 # this method can optionnally be invoked to ensure proper
223 # installation of the private key that belongs to this user
224 # installs private_key in working dir with expected name -- preserve mode
225 # typically user_private_key would be ~/.ssh/id_rsa
226 # xxx should probably check the 2 files are identical
227 def init_private_key_if_missing (self, user_private_key):
228 private_key_filename=self.private_key_filename()
229 if not os.path.isfile (private_key_filename):
230 key=self.plain_read(user_private_key)
231 self.plain_write(private_key_filename, key)
232 os.chmod(private_key_filename,os.stat(user_private_key).st_mode)
233 self.logger.debug("SfaClientBootstrap: Copied private key from %s into %s"%\
234 (user_private_key,private_key_filename))
236 #################### private details
238 def fullpath (self, file): return os.path.join (self.dir,file)
240 # the expected filenames for the various pieces
241 def private_key_filename (self):
242 return self.fullpath ("%s.pkey" % Xrn.unescape(self.hrn))
243 def self_signed_cert_filename (self):
244 return self.fullpath ("%s.sscert"%self.hrn)
245 def my_credential_filename (self):
246 return self.credential_filename (self.hrn, "user")
247 def credential_filename (self, hrn, type):
248 return self.fullpath ("%s.%s.cred"%(hrn,type))
249 def slice_credential_filename (self, hrn):
250 return self.credential_filename(hrn,'slice')
251 def authority_credential_filename (self, hrn):
252 return self.credential_filename(hrn,'authority')
253 def my_gid_filename (self):
254 return self.gid_filename (self.hrn, "user")
255 def gid_filename (self, hrn, type):
256 return self.fullpath ("%s.%s.gid"%(hrn,type))
259 # optimizing dependencies
260 # originally we used classes GID or Credential or Certificate
262 # return Credential(filename=self.my_credential()).save_to_string()
263 # but in order to make it simpler to other implementations/languages..
264 def plain_read (self, filename):
265 infile=file(filename,"r")
270 def plain_write (self, filename, contents):
271 outfile=file(filename,"w")
272 result=outfile.write(contents)
275 def assert_filename (self, filename, kind):
276 if not os.path.isfile (filename):
277 raise IOError,"Missing %s file %s"%(kind,filename)
280 def assert_private_key (self): return self.assert_filename (self.private_key_filename(),"private key")
281 def assert_self_signed_cert (self): return self.assert_filename (self.self_signed_cert_filename(),"self-signed certificate")
282 def assert_my_credential (self): return self.assert_filename (self.my_credential_filename(),"user's credential")
283 def assert_my_gid (self): return self.assert_filename (self.my_gid_filename(),"user's GID")
286 # decorator to make up the other methods
287 def get_or_produce (filename_method, produce_method, validate_method=None):
288 # default validator returns true
290 def wrapped (self, *args, **kw):
291 filename=filename_method (self, *args, **kw)
292 if os.path.isfile ( filename ):
293 if not validate_method:
295 elif validate_method(self, filename):
298 # remove invalid file
299 self.logger.warning ("Removing %s - has expired"%filename)
302 produce_method (self, filename, *args, **kw)
307 error = sys.exc_info()[:2]
308 message="Could not produce/retrieve %s (%s -- %s)"%\
309 (filename,error[0],error[1])
310 self.logger.log_exc(message)
311 raise Exception, message
315 @get_or_produce (self_signed_cert_filename, self_signed_cert_produce)
316 def self_signed_cert (self): pass
318 @get_or_produce (my_credential_filename, my_credential_produce, validate_credential)
319 def my_credential (self): pass
321 @get_or_produce (my_gid_filename, my_gid_produce)
322 def my_gid (self): pass
324 @get_or_produce (credential_filename, credential_produce, validate_credential)
325 def credential (self, hrn, type): pass
327 @get_or_produce (slice_credential_filename, slice_credential_produce, validate_credential)
328 def slice_credential (self, hrn): pass
330 @get_or_produce (authority_credential_filename, authority_credential_produce, validate_credential)
331 def authority_credential (self, hrn): pass
333 @get_or_produce (gid_filename, gid_produce)
334 def gid (self, hrn, type ): pass
337 # get the credentials as strings, for inserting as API arguments
338 def my_credential_string (self):
340 return self.plain_read(self.my_credential_filename())
341 def slice_credential_string (self, hrn):
342 self.slice_credential(hrn)
343 return self.plain_read(self.slice_credential_filename(hrn))
344 def authority_credential_string (self, hrn):
345 self.authority_credential(hrn)
346 return self.plain_read(self.authority_credential_filename(hrn))
349 def private_key (self):
350 self.assert_private_key()
351 return self.private_key_filename()