sfatables/xmlrule.py

   1 import libxml2
   2 from sfatables.globals import *
   3
   4 class XMLRule:
   5     rule_number = None
   6     chain = None
   7     xmldoc = None
   8     terminal = 0
   9
  10     arguments = {'match':None,'target':None}
  11     processors = {'match':None,'target':None}
  12     context = {'match':None,'target':None}
  13
  14     def apply_processor(self, type, rspec):
  15         processor = processors[type]
  16         styledoc = libxml2.parseFile(processor)
  17         style = libxslt.parseStylesheetDoc(styledoc)
  18         doc = libxml2.parseDoc(rspec)
  19         result = style.applyStylesheet(doc, None)
  20         processed_result = style.saveResultToString(result, 0)
  21         style.freeStylesheet()
  22         doc.freeDoc()
  23         result.freeDoc()
  24
  25         return stylesheet_result
  26
  27     def match(self, rspec):
  28         match_result = self.apply_processor('match',rspec)
  29         return (match_result=='True')
  30
  31     def target(self, rspec):
  32         target_result = self.apply_processor('target',rspec)
  33         return target_result
  34
  35     def apply_interpreted(self, rspec):
  36         # Interpreted
  37         #
  38         # output =
  39         #    if (match(match_args, rspec)
  40         #       then target(target_args, rspec)
  41         #       else rspec
  42
  43         if (self.match(rspec)):
  44             return self.target(rspec)
  45         else:
  46             return rspec
  47
  48
  49     def apply_compiled(rspec):
  50         # Not supported yet
  51         return None
  52
  53     def load_xml_extension (self, type, chain, rule_number):
  54         filename = sfatables_config+"/"+chain+"/"+"sfatables-%d-%s"%(rule_number,type)
  55
  56         self.xmldoc = libxml2.parseFile(filename)
  57         p = self.xmldoc.xpathNewContext()
  58
  59         context = p.xpathEval('//context/@select')
  60         self.context[type] = context[0].content
  61
  62         processor = p.xpathEval('//processor/@filename')
  63
  64         context = p.xpathEval('//attributes/attribute[@terminal="yes"]')
  65         if (context != []):
  66             self.terminal = 1
  67
  68         self.processors[type] = processor[0].content
  69         self.arguments[type] = p.xpathEval('//rule')
  70
  71         p.xpathFreeContext()
  72
  73
  74     def wrap_rspec (self, type, rspec):
  75         argument = self.arguments[type]
  76         p = rspec.xmldoc.xpathNewContext()
  77         root_node = p.xpathEval('/RSpec')
  78         if (not root_node or not root_node):
  79             raise Exception('An evil aggregate manager sent me a malformed RSpec. Please see the stack trace to identify it.')
  80
  81         root_node.addChild(arguments[type])
  82         return rspec
  83
  84     def __init__(self, chain, rule_number):
  85
  86         self.load_xml_extension('match', chain, rule_number)
  87         self.load_xml_extension('target',chain, rule_number)
  88         self.rule_number = rule_number
  89         self.chain = chain
  90
  91         return
  92
  93     def free(self):
  94         self.xmldoc.freeDoc()