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
14 import sfa.util.sfalogging
15 # importing sfa.utils.faults does pull a lot of stuff
16 # OTOH it's imported from Certificate anyways, so..
17 from sfa.util.faults import RecordNotFound
19 from sfa.client.sfaserverproxy import SfaServerProxy
21 # see optimizing dependencies below
22 from sfa.trust.certificate import Keypair, Certificate
23 from sfa.trust.credential import Credential
25 # a helper class to implement the bootstrapping of crypto. material
26 # assuming we are starting from scratch on the client side
27 # what's needed to complete a full slice creation cycle
29 # (*) a local private key
30 # (*) the corresp. public key in the registry
31 # (**) step1: a self-signed certificate
32 # default filename is <hrn>.sscert
33 # (**) step2: a user credential
34 # obtained at the registry with GetSelfCredential
35 # using the self-signed certificate as the SSL cert
36 # default filename is <hrn>.user.cred
37 # (**) step3: a registry-provided certificate (i.e. a GID)
38 # obtained at the registry using Resolve
39 # using the step2 credential as credential
40 # default filename is <hrn>.user.gid
42 # From that point on, the GID is used as the SSL certificate
43 # and the following can be done
45 # (**) retrieve a slice (or authority) credential
46 # obtained at the registry with GetCredential
47 # using the (step2) user-credential as credential
48 # default filename is <hrn>.<type>.cred
49 # (**) retrieve a slice (or authority) GID
50 # obtained at the registry with Resolve
51 # using the (step2) user-credential as credential
52 # default filename is <hrn>.<type>.cred
55 ########## Implementation notes
59 # this implementation is designed as a guideline for
60 # porting to other languages
62 # the decision to go for decorators aims at focusing
63 # on the core of what needs to be done when everything
64 # works fine, and to take caching and error management
67 # for non-pythonic developers, it should be enough to
68 # implement the bulk of this code, namely the _produce methods
69 # and to add caching and error management by whichever means
70 # is available, including inline
72 # (*) self-signed certificates
74 # still with other languages in mind, we've tried to keep the
75 # dependencies to the rest of the code as low as possible
77 # however this still relies on the sfa.trust.certificate module
78 # for the initial generation of a self-signed-certificate that
79 # is associated to the user's ssh-key
80 # (for user-friendliness, and for smooth operations with planetlab,
81 # the usage model is to reuse an existing keypair)
83 # there might be a more portable, i.e. less language-dependant way, to
84 # implement this step by exec'ing the openssl command a known
85 # successful attempt at this approach that worked for Java is
87 # http://nam.ece.upatras.gr/fstoolkit/trac/wiki/JavaSFAClient
91 class SfaClientException (Exception): pass
93 class SfaClientBootstrap:
95 # dir is mandatory but defaults to '.'
96 def __init__ (self, user_hrn, registry_url, dir=None,
97 verbose=False, timeout=None, logger=None):
99 self.registry_url=registry_url
100 if dir is None: dir="."
104 # default for the logger is to use the global sfa logger
106 logger = sfa.util.sfalogging.logger
109 ######################################## *_produce methods
111 # unconditionnally create a self-signed certificate
112 def self_signed_cert_produce (self,output):
113 self.assert_private_key()
114 private_key_filename = self.private_key_filename()
115 keypair=Keypair(filename=private_key_filename)
116 self_signed = Certificate (subject = self.hrn)
117 self_signed.set_pubkey (keypair)
118 self_signed.set_issuer (keypair, self.hrn)
120 self_signed.save_to_file (output)
121 self.logger.debug("SfaClientBootstrap: Created self-signed certificate for %s in %s"%\
126 # unconditionnally retrieve my credential (GetSelfCredential)
127 # we always use the self-signed-cert as the SSL cert
128 def my_credential_produce (self, output):
129 self.assert_self_signed_cert()
130 certificate_filename = self.self_signed_cert_filename()
131 certificate_string = self.plain_read (certificate_filename)
132 self.assert_private_key()
133 registry_proxy = SfaServerProxy (self.registry_url, self.private_key_filename(),
134 certificate_filename)
135 credential_string=registry_proxy.GetSelfCredential (certificate_string, self.hrn, "user")
136 self.plain_write (output, credential_string)
137 self.logger.debug("SfaClientBootstrap: Wrote result of GetSelfCredential in %s"%output)
141 # unconditionnally retrieve my GID - use the general form
142 def my_gid_produce (self,output):
143 return self.gid_produce (output, self.hrn, "user")
145 ### retrieve any credential (GetCredential) unconditionnal form
146 # we always use the GID as the SSL cert
147 def credential_produce (self, output, hrn, type):
149 certificate_filename = self.my_gid_filename()
150 self.assert_private_key()
151 registry_proxy = SfaServerProxy (self.registry_url, self.private_key_filename(),
152 certificate_filename)
153 self.assert_my_credential()
154 my_credential_string = self.my_credential_string()
155 credential_string=registry_proxy.GetCredential (my_credential_string, hrn, type)
156 self.plain_write (output, credential_string)
157 self.logger.debug("SfaClientBootstrap: Wrote result of GetCredential in %s"%output)
160 def slice_credential_produce (self, output, hrn):
161 return self.credential_produce (output, hrn, "slice")
163 def authority_credential_produce (self, output, hrn):
164 return self.credential_produce (output, hrn, "authority")
166 ### retrieve any gid (Resolve) - unconditionnal form
167 # use my GID when available as the SSL cert, otherwise the self-signed
168 def gid_produce (self, output, hrn, type ):
171 certificate_filename = self.my_gid_filename()
173 self.assert_self_signed_cert()
174 certificate_filename = self.self_signed_cert_filename()
176 self.assert_private_key()
177 registry_proxy = SfaServerProxy (self.registry_url, self.private_key_filename(),
178 certificate_filename)
179 credential_string=self.plain_read (self.my_credential())
180 records = registry_proxy.Resolve (hrn, credential_string)
181 records=[record for record in records if record['type']==type]
183 raise RecordNotFound, "hrn %s (%s) unknown to registry %s"%(hrn,type,self.registry_url)
185 self.plain_write (output, record['gid'])
186 self.logger.debug("SfaClientBootstrap: Wrote GID for %s (%s) in %s"% (hrn,type,output))
190 # Returns True if credential file is valid. Otherwise return false.
191 def validate_credential(self, filename):
193 cred = Credential(filename=filename)
194 # check if credential is expires
195 if cred.get_expiration() < datetime.now():
200 #################### public interface
202 # return my_gid, run all missing steps in the bootstrap sequence
203 def bootstrap_my_gid (self):
204 self.self_signed_cert()
208 # once we've bootstrapped we can use this object to issue any other SFA call
210 def server_proxy (self, url):
212 return SfaServerProxy (url, self.private_key_filename(), self.my_gid_filename(),
213 verbose=self.verbose, timeout=self.timeout)
215 # now in some cases the self-signed is enough
216 def server_proxy_simple (self, url):
217 self.assert_self_signed_cert()
218 return SfaServerProxy (url, self.private_key_filename(), self.self_signed_cert_filename(),
219 verbose=self.verbose, timeout=self.timeout)
221 # this method can optionnally be invoked to ensure proper
222 # installation of the private key that belongs to this user
223 # installs private_key in working dir with expected name -- preserve mode
224 # typically user_private_key would be ~/.ssh/id_rsa
225 # xxx should probably check the 2 files are identical
226 def init_private_key_if_missing (self, user_private_key):
227 private_key_filename=self.private_key_filename()
228 if not os.path.isfile (private_key_filename):
229 key=self.plain_read(user_private_key)
230 self.plain_write(private_key_filename, key)
231 os.chmod(private_key_filename,os.stat(user_private_key).st_mode)
232 self.logger.debug("SfaClientBootstrap: Copied private key from %s into %s"%\
233 (user_private_key,private_key_filename))
235 #################### private details
237 def fullpath (self, file): return os.path.join (self.dir,file)
239 # the expected filenames for the various pieces
240 def private_key_filename (self):
241 return self.fullpath ("%s.pkey"%self.hrn)
242 def self_signed_cert_filename (self):
243 return self.fullpath ("%s.sscert"%self.hrn)
244 def my_credential_filename (self):
245 return self.credential_filename (self.hrn, "user")
246 def credential_filename (self, hrn, type):
247 return self.fullpath ("%s.%s.cred"%(hrn,type))
248 def slice_credential_filename (self, hrn):
249 return self.credential_filename(hrn,'slice')
250 def authority_credential_filename (self, hrn):
251 return self.credential_filename(hrn,'authority')
252 def my_gid_filename (self):
253 return self.gid_filename (self.hrn, "user")
254 def gid_filename (self, hrn, type):
255 return self.fullpath ("%s.%s.gid"%(hrn,type))
258 # optimizing dependencies
259 # originally we used classes GID or Credential or Certificate
261 # return Credential(filename=self.my_credential()).save_to_string()
262 # but in order to make it simpler to other implementations/languages..
263 def plain_read (self, filename):
264 infile=file(filename,"r")
269 def plain_write (self, filename, contents):
270 outfile=file(filename,"w")
271 result=outfile.write(contents)
274 def assert_filename (self, filename, kind):
275 if not os.path.isfile (filename):
276 raise IOError,"Missing %s file %s"%(kind,filename)
279 def assert_private_key (self): return self.assert_filename (self.private_key_filename(),"private key")
280 def assert_self_signed_cert (self): return self.assert_filename (self.self_signed_cert_filename(),"self-signed certificate")
281 def assert_my_credential (self): return self.assert_filename (self.my_credential_filename(),"user's credential")
282 def assert_my_gid (self): return self.assert_filename (self.my_gid_filename(),"user's GID")
285 # decorator to make up the other methods
286 def get_or_produce (filename_method, produce_method, validate_method=None):
287 # default validator returns true
289 def wrapped (self, *args, **kw):
290 filename=filename_method (self, *args, **kw)
291 if os.path.isfile ( filename ):
292 if not validate_method:
294 elif validate_method(self, filename):
297 # remove invalid file
298 self.logger.warning ("Removing %s - has expired"%filename)
301 produce_method (self, filename, *args, **kw)
306 error = sys.exc_info()[:2]
307 message="Could not produce/retrieve %s (%s -- %s)"%\
308 (filename,error[0],error[1])
309 self.logger.log_exc(message)
310 raise Exception, message
314 @get_or_produce (self_signed_cert_filename, self_signed_cert_produce)
315 def self_signed_cert (self): pass
317 @get_or_produce (my_credential_filename, my_credential_produce, validate_credential)
318 def my_credential (self): pass
320 @get_or_produce (my_gid_filename, my_gid_produce)
321 def my_gid (self): pass
323 @get_or_produce (credential_filename, credential_produce, validate_credential)
324 def credential (self, hrn, type): pass
326 @get_or_produce (slice_credential_filename, slice_credential_produce, validate_credential)
327 def slice_credential (self, hrn): pass
329 @get_or_produce (authority_credential_filename, authority_credential_produce, validate_credential)
330 def authority_credential (self, hrn): pass
332 @get_or_produce (gid_filename, gid_produce)
333 def gid (self, hrn, type ): pass
336 # get the credentials as strings, for inserting as API arguments
337 def my_credential_string (self):
339 return self.plain_read(self.my_credential_filename())
340 def slice_credential_string (self, hrn):
341 self.slice_credential(hrn)
342 return self.plain_read(self.slice_credential_filename(hrn))
343 def authority_credential_string (self, hrn):
344 self.authority_credential(hrn)
345 return self.plain_read(self.authority_credential_filename(hrn))
348 def private_key (self):
349 self.assert_private_key()
350 return self.private_key_filename()