Source Code for Module dns.rcode

  1  # Copyright (C) 2001-2007, 2009-2011 Nominum, Inc. 
  2  # 
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 13  # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 
 14  # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 
 15   
 16  """DNS Result Codes.""" 
 17   
 18  import dns.exception 
 19   
 20  NOERROR = 0 
 21  FORMERR = 1 
 22  SERVFAIL = 2 
 23  NXDOMAIN = 3 
 24  NOTIMP = 4 
 25  REFUSED = 5 
 26  YXDOMAIN = 6 
 27  YXRRSET = 7 
 28  NXRRSET = 8 
 29  NOTAUTH = 9 
 30  NOTZONE = 10 
 31  BADVERS = 16 
 32   
 33  _by_text = { 
 34      'NOERROR' : NOERROR, 
 35      'FORMERR' : FORMERR, 
 36      'SERVFAIL' : SERVFAIL, 
 37      'NXDOMAIN' : NXDOMAIN, 
 38      'NOTIMP' : NOTIMP, 
 39      'REFUSED' : REFUSED, 
 40      'YXDOMAIN' : YXDOMAIN, 
 41      'YXRRSET' : YXRRSET, 
 42      'NXRRSET' : NXRRSET, 
 43      'NOTAUTH' : NOTAUTH, 
 44      'NOTZONE' : NOTZONE, 
 45      'BADVERS' : BADVERS 
 46  } 
 47   
 48  # We construct the inverse mapping programmatically to ensure that we 
 49  # cannot make any mistakes (e.g. omissions, cut-and-paste errors) that 
 50  # would cause the mapping not to be a true inverse. 
 51   
 52  _by_value = dict([(y, x) for x, y in _by_text.iteritems()]) 
 53   
 54   
 55 -class UnknownRcode(dns.exception.DNSException): 
 56      """A DNS rcode is unknown.""" 
 57   
 58 -def from_text(text): 
 59      """Convert text into an rcode. 
 60   
 61      @param text: the texual rcode 
 62      @type text: string 
 63      @raises UnknownRcode: the rcode is unknown 
 64      @rtype: int 
 65      """ 
 66   
 67      if text.isdigit(): 
 68          v = int(text) 
 69          if v >= 0 and v <= 4095: 
 70              return v 
 71      v = _by_text.get(text.upper()) 
 72      if v is None: 
 73          raise UnknownRcode 
 74      return v 
 75   
 76 -def from_flags(flags, ednsflags): 
 77      """Return the rcode value encoded by flags and ednsflags. 
 78   
 79      @param flags: the DNS flags 
 80      @type flags: int 
 81      @param ednsflags: the EDNS flags 
 82      @type ednsflags: int 
 83      @raises ValueError: rcode is < 0 or > 4095 
 84      @rtype: int 
 85      """ 
 86   
 87      value = (flags & 0x000f) | ((ednsflags >> 20) & 0xff0) 
 88      if value < 0 or value > 4095: 
 89          raise ValueError('rcode must be >= 0 and <= 4095') 
 90      return value 
 91   
 92 -def to_flags(value): 
 93      """Return a (flags, ednsflags) tuple which encodes the rcode. 
 94   
 95      @param value: the rcode 
 96      @type value: int 
 97      @raises ValueError: rcode is < 0 or > 4095 
 98      @rtype: (int, int) tuple 
 99      """ 
100   
101      if value < 0 or value > 4095: 
102          raise ValueError('rcode must be >= 0 and <= 4095') 
103      v = value & 0xf 
104      ev = long(value & 0xff0) << 20 
105      return (v, ev) 
106   
107 -def to_text(value): 
108      """Convert rcode into text. 
109   
110      @param value: the rcode 
111      @type value: int 
112      @rtype: string 
113      """ 
114   
115      text = _by_value.get(value) 
116      if text is None: 
117          text = str(value) 
118      return text 
119