very first draft of an sfa client library for bootstrapping user gid

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diff --git a/sfa/client/sfaclientlib.py b/sfa/client/sfaclientlib.py
new file mode 100644 (file)
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+++ b/sfa/client/sfaclientlib.py
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+#
+# a minimal library for writing "lightweight" SFA clients
+#
+
+import os,os.path
+
+import sfa.util.sfalogging
+
+from sfa.trust.gid import GID
+from sfa.trust.certificate import Keypair, Certificate
+from sfa.trust.credential import Credential
+
+import sfa.client.sfaprotocol as sfaprotocol
+
+class SfaServerProxy:
+
+    def __init__ (self, url, keyfile, certfile, verbose=False, timeout=None):
+        self.url=url
+        self.keyfile=keyfile
+        self.certfile=certfile
+        self.verbose=verbose
+        self.timeout=timeout
+        # an instance of xmlrpclib.ServerProxy
+        self.serverproxy=sfaprotocol.server_proxy \
+            (self.url, self.keyfile, self.certfile, self.timeout, self.verbose)
+
+    # this is python magic to return the code to run when 
+    # SfaServerProxy receives a method call
+    # so essentially we send the same method with identical arguments
+    # to the server_proxy object
+    def __getattr__(self, name):
+        def func(*args, **kwds):
+            return getattr(self.serverproxy, name)(*args, **kwds)
+        return func
+    
+
+########## 
+# a helper class to implement the bootstrapping of crypto. material
+# assuming we are starting from scratch on the client side 
+# what's needed to complete a full slice creation cycle
+# (**) prerequisites: 
+#  (*) a local private key 
+#  (*) the corresp. public key in the registry 
+# (**) step1: a self-signed certificate
+#      default filename is <hrn>.sscert
+# (**) step2: a user credential
+#      obtained at the registry with GetSelfCredential
+#      using the self-signed certificate as the SSL cert
+#      default filename is <hrn>.user.cred
+# (**) step3: a registry-provided certificate (i.e. a GID)
+#      obtained at the registry using Resolve
+#      using the step2 credential as credential
+#      default filename is <hrn>.user.gid
+##########
+# from that point on, the GID can/should be used as the SSL cert for anything
+# a new (slice) credential would be needed for slice operations and can be 
+# obtained at the registry through GetCredential
+
+# xxx todo should protect against write file permissions
+# xxx todo review exceptions
+class SfaClientBootstrap:
+
+    # xxx todo should account for verbose and timeout that the proxy offers
+    def __init__ (self, user_hrn, registry_url, dir=None, logger=None):
+        self.hrn=user_hrn
+        self.registry_url=registry_url
+        if dir is None: dir="."
+        self.dir=dir
+        if logger is None: 
+            print 'special case for logger'
+            logger = sfa.util.sfalogging.logger
+        self.logger=logger
+    
+    # stupid stuff
+    def fullpath (self, file): return os.path.join (self.dir,file)
+    # %s -> self.hrn
+    def fullpath_format(self,format): return self.fullpath (format%self.hrn)
+
+    def private_key_file (self): 
+        return self.fullpath_format ("%s.pkey")
+
+    def self_signed_cert_file (self): 
+        return self.fullpath_format ("%s.sscert")
+    def credential_file (self): 
+        return self.fullpath_format ("%s.user.cred")
+    def gid_file (self): 
+        return self.fullpath_format ("%s.user.gid")
+
+    def check_private_key (self):
+        if not os.path.isfile (self.private_key_file()):
+            raise Exception,"No such file %s"%self.private_key_file()
+        return True
+
+    # typically user_private_key is ~/.ssh/id_rsa
+    def init_private_key_if_missing (self, user_private_key):
+        private_key_file=self.private_key_file()
+        if not os.path.isfile (private_key_file):
+            infile=file(user_private_key)
+            outfile=file(private_key_file,'w')
+            outfile.write(infile.read())
+            outfile.close()
+            infile.close()
+            os.chmod(private_key_file,os.stat(user_private_key).st_mode)
+            self.logger.debug("SfaClientBootstrap: Copied private key from %s into %s"%\
+                                  (user_private_key,private_key_file))
+        
+
+    # get any certificate, gid preferred
+    def preferred_certificate_file (self):
+        attempts=[ self.gid_file(), self.self_signed_cert_file() ]
+        for attempt in attempts:
+            if os.path.isfile (attempt): return attempt
+        return None
+
+    ### step1
+    # unconditionnally
+    def create_self_signed_certificate (self,output):
+        self.check_private_key()
+        private_key_file = self.private_key_file()
+        keypair=Keypair(filename=private_key_file)
+        self_signed = Certificate (subject = self.hrn)
+        self_signed.set_pubkey (keypair)
+        self_signed.set_issuer (keypair, self.hrn)
+        self_signed.sign ()
+        self_signed.save_to_file (output)
+        self.logger.debug("SfaClientBootstrap: Created self-signed certificate for %s in %s"%\
+                              (self.hrn,output))
+        return output
+
+    def get_self_signed_cert (self):
+        self_signed_cert_file = self.self_signed_cert_file()
+        if os.path.isfile (self_signed_cert_file):
+            return self_signed_cert_file
+        return self.create_self_signed_certificate(self_signed_cert_file)
+        
+    ### step2 
+    # unconditionnally
+    def retrieve_credential (self, output):
+        self.check_private_key()
+        certificate_file = self.preferred_certificate_file()
+        registry_proxy = SfaServerProxy (self.registry_url, self.private_key_file(),
+                                         certificate_file)
+        certificate = Certificate (filename=certificate_file)
+        certificate_string = certificate.save_to_string(save_parents=True)
+        credential_string=registry_proxy.GetSelfCredential (certificate_string, self.hrn, "user")
+        credential = Credential (string=credential_string)
+        credential.save_to_file (output, save_parents=True)
+        self.logger.debug("SfaClientBootstrap: Wrote result of GetSelfCredential in %s"%output)
+        return output
+
+    def get_credential (self):
+        credential_file = self.credential_file ()
+        if os.path.isfile(credential_file): 
+            return credential_file
+        return self.retrieve_credential (credential_file)
+
+    def get_credential_string (self):
+        return Credential(filename=self.get_credential()).save_to_string()
+
+    ### step3
+    # unconditionnally
+    def retrieve_gid (self, hrn, type, output):
+         self.check_private_key()
+         certificate_file = self.preferred_certificate_file()
+         registry_proxy = SfaServerProxy (self.registry_url, self.private_key_file(),
+                                          certificate_file)
+         credential_string=Credential(filename=self.credential_file()).save_to_string()
+         records = registry_proxy.Resolve (hrn, credential_string)
+         records=[record for record in records if record['type']==type]
+         if not records:
+             # RecordNotFound
+             raise Exception, "hrn %s (%s) unknown to registry %s"%(hrn,type,self.registry_url)
+         record=records[0]
+         gid=GID(string=record['gid'])
+         gid.save_to_file (filename=output)
+         self.logger.debug("SfaClientBootstrap: Wrote GID for %s (%s) in %s"% (hrn,type,output))
+         return output
+
+    def get_gid (self):
+        gid_file=self.gid_file()
+        if os.path.isfile(gid_file): 
+            return gid_file
+        return self.retrieve_gid(self.hrn, "user", gid_file)
+
+    # make sure we have the GID at hand
+    def bootstrap_gid (self):
+        if self.preferred_certificate_file() is None:
+            self.get_self_signed_cert()
+        self.get_credential()
+        self.get_gid()
+
+    def server_proxy (self, url):
+        return SfaServerProxy (url, self.private_key_file(), self.gid_file())
+