Source Code for Module ganeti.utils.hash

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 29   
 30  """Utility functions for hashing. 
 31   
 32  """ 
 33   
 34  import os 
 35  import hmac 
 36   
 37  from ganeti import compat 
 38   
 39   
 40 -def Sha1Hmac(key, text, salt=None): 
 41    """Calculates the HMAC-SHA1 digest of a text. 
 42   
 43    HMAC is defined in RFC2104. 
 44   
 45    @type key: string 
 46    @param key: Secret key 
 47    @type text: string 
 48   
 49    """ 
 50    if salt: 
 51      salted_text = salt + text 
 52    else: 
 53      salted_text = text 
 54   
 55    return hmac.new(key, salted_text, compat.sha1).hexdigest() 
 56   
 57   
 58 -def VerifySha1Hmac(key, text, digest, salt=None): 
 59    """Verifies the HMAC-SHA1 digest of a text. 
 60   
 61    HMAC is defined in RFC2104. 
 62   
 63    @type key: string 
 64    @param key: Secret key 
 65    @type text: string 
 66    @type digest: string 
 67    @param digest: Expected digest 
 68    @rtype: bool 
 69    @return: Whether HMAC-SHA1 digest matches 
 70   
 71    """ 
 72    return digest.lower() == Sha1Hmac(key, text, salt=salt).lower() 
 73   
 74   
 75 -def _FingerprintFile(filename): 
 76    """Compute the fingerprint of a file. 
 77   
 78    If the file does not exist, a None will be returned 
 79    instead. 
 80   
 81    @type filename: str 
 82    @param filename: the filename to checksum 
 83    @rtype: str 
 84    @return: the hex digest of the sha checksum of the contents 
 85        of the file 
 86   
 87    """ 
 88    if not (os.path.exists(filename) and os.path.isfile(filename)): 
 89      return None 
 90   
 91    f = open(filename) 
 92   
 93    fp = compat.sha1_hash() 
 94    while True: 
 95      data = f.read(4096) 
 96      if not data: 
 97        break 
 98   
 99      fp.update(data) 
100   
101    return fp.hexdigest() 
102   
103   
104 -def FingerprintFiles(files): 
105    """Compute fingerprints for a list of files. 
106   
107    @type files: list 
108    @param files: the list of filename to fingerprint 
109    @rtype: dict 
110    @return: a dictionary filename: fingerprint, holding only 
111        existing files 
112   
113    """ 
114    ret = {} 
115   
116    for filename in files: 
117      cksum = _FingerprintFile(filename) 
118      if cksum: 
119        ret[filename] = cksum 
120   
121    return ret 
122