cluther · September 12, 2013 14:57 · Sep 12, 2013
diff --git a/krb5_ccache.py b/krb5_ccache.py
@@ -0,0 +1,355 @@
+#!/usr/bin/env python
+##############################################################################
+#
+# Copyright (C) Zenoss, Inc. 2013, all rights reserved.
+#
+# This content is made available according to terms specified in
+# License.zenoss under the directory where your Zenoss product is installed.
+#
+##############################################################################
+
+'''
+Module for reading krb5 credential cache files. See the following link
+for documentation on the file format.
+
+    http://repo.or.cz/w/krb5dissect.git/blob_plain/HEAD:/ccache.txt
+'''
+
+from base64 import b64encode
+from datetime import datetime
+from struct import unpack
+
+
+class CCache(object):
+    file_format_version = None  # uint16 (H,2)
+    headerlen = None            # uint16 (H,2)
+    headers = None              # Header[]
+    primary_principal = None    # Principal[]
+    credentials = None          # Credential[]
+
+    size = None
+
+    def __init__(self, data):
+        self.size = len(data)
+
+        # Track to which byte we've read in data.
+        idx = 0
+
+        self.file_format_version, self.headerlen = unpack(
+            '!HH', data[idx:idx+4])
+
+        idx += 4
+
+        # Remember idx where headers start.
+        headers_idx = idx
+
+        # Add headers.
+        self.headers = []
+        while idx < headers_idx + self.headerlen:
+            header = Header(data[idx:idx+self.headerlen])
+            idx += header.size
+            self.headers.append(header)
+
+        # Add primary_principal.
+        self.primary_principal = Principal(data[idx:])
+        idx += self.primary_principal.size
+
+        # Add credentials.
+        self.credentials = []
+        while idx < self.size:
+            credential = Credential(data[idx:])
+            idx += credential.size
+            self.credentials.append(credential)
+
+    def __str__(self):
+        return (
+            "File format version: {0}\n"
+            "Header length: {1}\n"
+            "Headers:\n{2}\n"
+            "Primary Principal:\n{3}\n"
+            "Credentials:\n{4}\n".format(
+                self.file_format_version,
+                self.headerlen,
+                '\n'.join(map(str, self.headers)),
+                str(self.primary_principal),
+                '\n'.join(map(str, self.credentials))))
+
+
+class Header(object):
+    tag = None                  # uint16 (H,2)
+    taglen = None               # uint16 (H,2)
+    tagdata = None              # uint8[] | DeltaTime
+
+    size = None
+
+    def __init__(self, data):
+        self.size = 0
+
+        self.tag, self.taglen = unpack('!HH', data[:4])
+
+        if self.tag == 1:
+            self.tagdata = DeltaTime(data[4:4+self.taglen])
+        else:
+            self.tagdata = unpack('!%dc' % self.taglen, data[4:4+self.taglen])
+
+        self.size = 4 + self.taglen
+
+    def __str__(self):
+        return (
+            "  Tag: {0}\n"
+            "  Tag length: {1}\n"
+            "  Tag data: {2}\n".format(
+                self.tag,
+                self.taglen,
+                str(self.tagdata)))
+
+
+class DeltaTime(object):
+    time_offset = None          # uint32 (I,4)
+    usec_offset = None          # uint32 (I,4)
+
+    size = None
+
+    def __init__(self, data):
+        self.time_offset, self.usec_offset = unpack('!II', data)
+        self.size = len(data)
+
+    def __str__(self):
+        return "DeltaTime (time_offset:{0}, usec_offset:{1})".format(
+            self.time_offset, self.usec_offset)
+
+
+class Credential(object):
+    client = None               # Principal
+    server = None               # Principal
+    key = None                  # KeyBlock
+    time = None                 # Times
+    is_skey = None              # uint8 (B,1)
+    tktflags = None             # uint32 (I,4)
+    num_address = None          # uint32 (I,4)
+    addrs = None                # Address[]
+    num_authdata = None         # uint32 (I,4)
+    authdata = None             # AuthData[]
+    ticket = None               # CountedOctetString
+    second_ticket = None        # CountedOctetString
+
+    size = None
+
+    def __init__(self, data):
+        self.client = Principal(data[0:])
+        idx = self.client.size
+
+        self.server = Principal(data[idx:])
+        idx += self.server.size
+
+        self.key = KeyBlock(data[idx:])
+        idx += self.key.size
+
+        self.time = Times(data[idx:])
+        idx += self.time.size
+
+        self.is_skey, self.tktflags, self.num_address = unpack(
+            '!BII', data[idx:idx+9])
+
+        idx += 9
+
+        self.addrs = []
+        while len(self.addrs) < self.num_address:
+            address = Address(data[idx:])
+            self.addrs.append(address)
+            idx += address.size
+
+        self.num_authdata, = unpack('!I', data[idx:idx+4])
+        idx += 4
+
+        self.authdata = []
+        while len(self.authdata) < self.num_authdata:
+            authdata = AuthData(data[idx:])
+            self.authdata.append(authdata)
+            idx += authdata.size
+
+        self.ticket = Ticket(data[idx:])
+        idx += self.ticket.size
+
+        self.second_ticket = Ticket(data[idx:])
+        idx += self.second_ticket.size
+
+        self.size = idx
+
+    def __str__(self):
+        return (
+            "  Client: {0}\n"
+            "  Server: {1}\n"
+            "  Key: {2}\n"
+            "  Times:\n{3}\n"
+            "  SKey: {4}\n"
+            "  Ticket flags: {5}\n"
+            "  Addresses: {6}\n"
+            "  Auth data: {7}\n"
+            "  Ticket: {8}\n\n"
+            "  Second ticket: {9}\n\n".format(
+                str(self.client),
+                str(self.server),
+                str(self.key),
+                str(self.time),
+                'Yes' if self.is_skey else 'No',
+                self.tktflags,
+                str(self.addrs),
+                str(self.authdata),
+                str(self.ticket),
+                str(self.second_ticket)))
+
+
+class KeyBlock(object):
+    keytype = None              # uint16 (H,2)
+    etype = None                # uint16 (H,2)
+    keylen = None               # uint16 (H,2)
+    keyvalue = None             # uint8[]
+
+    size = None
+
+    def __init__(self, data):
+        self.keytype, self.etype, self.keylen = unpack('!HHH', data[:6])
+        self.keyvalue = unpack('!%dc' % self.keylen, data[6:6+self.keylen])
+        self.size = 6 + self.keylen
+
+    def __str__(self):
+        return b64encode(''.join(self.keyvalue))
+
+
+class Times(object):
+    authtime = None             # uint32 (I,4)
+    starttime = None            # uint32 (I,4)
+    endtime = None              # uint32 (I,4)
+    renew_till = None           # uint32 (I,4)
+
+    size = None
+
+    def __init__(self, data):
+        self.size = 16
+        self.authtime, self.starttime, self.endtime, self.renew_till = unpack(
+            '!IIII', data[:self.size])
+
+    def __str__(self):
+        return (
+            "    Auth: {0}\n"
+            "    Start: {1}\n"
+            "    End: {2}\n"
+            "    Renew till: {3}\n".format(
+                datetime.fromtimestamp(self.authtime).isoformat(),
+                datetime.fromtimestamp(self.starttime).isoformat(),
+                datetime.fromtimestamp(self.endtime).isoformat(),
+                datetime.fromtimestamp(self.renew_till).isoformat()))
+
+
+class Address(object):
+    addrtype = None             # uint16 (H,2)
+    addrdata = None             # CountedOctetString
+
+    size = None
+
+    def __init__(self, data):
+        self.addrtype, = unpack('!H', data[:2])
+        self.addrdata = CountedOctetString(data[2:])
+        self.size = 2 + self.addrdata.size
+
+
+class AuthData(object):
+    authtype = None             # uint16 (H,2)
+    authdata = None             # CountedOctetString
+
+    size = None
+
+    def __init__(self, data):
+        self.authtype, = unpack('!H', data[:2])
+        self.authdata = CountedOctetString(data[2:])
+        self.size = 2 + self.authdata.size
+
+
+class Principal(object):
+    name_type = None            # uint16 (I,4)
+    num_components = None       # uint16 (I,4)
+    realm = None                # CountedOctetString
+    components = None           # CountedOctetString[]
+
+    size = None
+
+    def __init__(self, data):
+        self.name_type, self.num_components = unpack('!II', data[:8])
+
+        idx = 8
+
+        self.realm = CountedOctetString(data[idx:])
+        idx += self.realm.size
+
+        self.components = []
+        while len(self.components) < self.num_components:
+            component = CountedOctetString(data[idx:])
+            self.components.append(component)
+            idx += component.size
+
+        self.size = idx
+
+    def __str__(self):
+        return ', '.join(
+            ('{0}@{1}'.format(
+                str(x), str(self.realm)) for x in self.components))
+
+
+class CountedOctetString(object):
+    length = None               # uint32 (I, 4)
+    data = None                 # uint8[]
+
+    size = None
+
+    def __init__(self, data):
+        self.length, = unpack('!I', data[:4])
+        self.data = unpack('!%dc' % self.length, data[4:4+self.length])
+        self.size = 4 + self.length
+
+    def __str__(self):
+        return ''.join(self.data)
+
+    def __repr__(self):
+        return repr(str(self))
+
+
+class Ticket(CountedOctetString):
+    def __str__(self):
+        return b64encode(super(Ticket, self).__str__())
+
+
+def main():
+    import optparse
+    import os
+    import tempfile
+
+    parser = optparse.OptionParser()
+    parser.add_option(
+        '-d', '--debug',
+        default=False, action='store_true',
+        help='Open pdb once ccache has been loaded')
+
+    options, args = parser.parse_args()
+
+    if len(args) > 0:
+        ccache_filename = args[0]
+    else:
+        ccache_filename = os.path.join(
+            tempfile.gettempdir(),
+            'krb5cc_{0}'.format(os.getuid()))
+
+    with open(ccache_filename, 'rb') as f:
+        ccache = CCache(f.read())
+
+    print ccache
+
+    if options.debug:
+        print "Opening pdb. See the 'ccache' object."
+        import pdb
+        pdb.set_trace()
+        pass
+
+
+if __name__ == '__main__':
+    main()
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