Source Code for Module ganeti.utils.hash

  1  # 
  2  # 
  3   
  4  # Copyright (C) 2006, 2007, 2010, 2011 Google Inc. 
  5  # 
  6  # This program is free software; you can redistribute it and/or modify 
  7  # it under the terms of the GNU General Public License as published by 
  8  # the Free Software Foundation; either version 2 of the License, or 
  9  # (at your option) any later version. 
 10  # 
 11  # This program is distributed in the hope that it will be useful, but 
 12  # WITHOUT ANY WARRANTY; without even the implied warranty of 
 13  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU 
 14  # General Public License for more details. 
 15  # 
 16  # You should have received a copy of the GNU General Public License 
 17  # along with this program; if not, write to the Free Software 
 18  # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 
 19  # 02110-1301, USA. 
 20   
 21  """Utility functions for hashing. 
 22   
 23  """ 
 24   
 25  import os 
 26  import hmac 
 27   
 28  from ganeti import compat 
 29   
 30   
 31 -def Sha1Hmac(key, text, salt=None): 
 32    """Calculates the HMAC-SHA1 digest of a text. 
 33   
 34    HMAC is defined in RFC2104. 
 35   
 36    @type key: string 
 37    @param key: Secret key 
 38    @type text: string 
 39   
 40    """ 
 41    if salt: 
 42      salted_text = salt + text 
 43    else: 
 44      salted_text = text 
 45   
 46    return hmac.new(key, salted_text, compat.sha1).hexdigest() 
 47   
 48   
 49 -def VerifySha1Hmac(key, text, digest, salt=None): 
 50    """Verifies the HMAC-SHA1 digest of a text. 
 51   
 52    HMAC is defined in RFC2104. 
 53   
 54    @type key: string 
 55    @param key: Secret key 
 56    @type text: string 
 57    @type digest: string 
 58    @param digest: Expected digest 
 59    @rtype: bool 
 60    @return: Whether HMAC-SHA1 digest matches 
 61   
 62    """ 
 63    return digest.lower() == Sha1Hmac(key, text, salt=salt).lower() 
 64   
 65   
 66 -def _FingerprintFile(filename): 
 67    """Compute the fingerprint of a file. 
 68   
 69    If the file does not exist, a None will be returned 
 70    instead. 
 71   
 72    @type filename: str 
 73    @param filename: the filename to checksum 
 74    @rtype: str 
 75    @return: the hex digest of the sha checksum of the contents 
 76        of the file 
 77   
 78    """ 
 79    if not (os.path.exists(filename) and os.path.isfile(filename)): 
 80      return None 
 81   
 82    f = open(filename) 
 83   
 84    fp = compat.sha1_hash() 
 85    while True: 
 86      data = f.read(4096) 
 87      if not data: 
 88        break 
 89   
 90      fp.update(data) 
 91   
 92    return fp.hexdigest() 
 93   
 94   
 95 -def FingerprintFiles(files): 
 96    """Compute fingerprints for a list of files. 
 97   
 98    @type files: list 
 99    @param files: the list of filename to fingerprint 
100    @rtype: dict 
101    @return: a dictionary filename: fingerprint, holding only 
102        existing files 
103   
104    """ 
105    ret = {} 
106   
107    for filename in files: 
108      cksum = _FingerprintFile(filename) 
109      if cksum: 
110        ret[filename] = cksum 
111   
112    return ret 
113