sfatables/xmlrule.py

   1 import libxml2
   2 import libxslt
   3 from sfatables.globals import *
   4
   5 class XMLRule:
   6     def apply_processor(self, type, doc, output_xpath_filter=None):
   7         processor = self.processors[type]
   8
   9         # XXX TO CLEAN UP
  10         filepath = os.path.join(sfatables_config, 'processors', processor)
  11         # XXX
  12
  13         print filepath
  14         styledoc = libxml2.parseFile(filepath)
  15         style = libxslt.parseStylesheetDoc(styledoc)
  16         result = style.applyStylesheet(doc, None)
  17         if (output_xpath_filter):
  18             p = result.xpathNewContext()
  19             xpath_result = p.xpathEval(output_xpath_filter)
  20             if (xpath_result == []):
  21                 raise Exception("Could not apply processor %s."%processor)
  22
  23             stylesheet_result = xpath_result
  24             p.xpathFreeContext()
  25         else:
  26             stylesheet_result = result #style.saveResultToString(result)
  27
  28         style.freeStylesheet()
  29         #doc.freeDoc()
  30         #result.freeDoc()
  31
  32         return stylesheet_result
  33
  34     def wrap_up(self, doc):
  35         filepath = os.path.join(sfatables_config, 'processors', self.final_processor)
  36
  37         if not os.path.exists(filepath):
  38             raise Exception('Could not find final rule filter')
  39
  40         styledoc = libxml2.parseFile(filepath)
  41         style = libxslt.parseStylesheetDoc(styledoc)
  42         result = style.applyStylesheet(doc, None)
  43         stylesheet_result = result#style.saveResultToString(result)
  44         style.freeStylesheet()
  45         #doc.freeDoc()
  46         #result.freeDoc()
  47
  48         return stylesheet_result
  49
  50     def match(self, rspec):
  51         match_result = self.apply_processor('match',rspec,"//result/@verdict")
  52         return (match_result[0].content=='True')
  53
  54     def target(self, rspec):
  55         target_result = self.apply_processor('target',rspec,None)
  56         return target_result
  57
  58     def apply_interpreted(self, rspec):
  59         # Interpreted
  60         #
  61         # output =
  62         #    if (match(match_args, rspec)
  63         #       then target(target_args, rspec)
  64         #       else rspec
  65
  66         if (self.match(rspec)):
  67             return self.target(rspec)
  68         else:
  69             return rspec
  70
  71
  72     def apply_compiled(rspec):
  73         # Not supported yet
  74         return None
  75
  76     def load_xml_extension (self, type, chain, rule_number):
  77         filename = sfatables_config+"/"+chain+"/"+"sfatables-%d-%s"%(rule_number,type)
  78
  79         self.xmldoc = libxml2.parseFile(filename)
  80         p = self.xmldoc.xpathNewContext()
  81
  82         context = p.xpathEval('//context/@select')
  83         self.context[type] = context[0].content
  84
  85         processor = p.xpathEval('//processor/@filename')
  86
  87         context = p.xpathEval('//attributes/attribute[@terminal="yes"]')
  88         if (context != []):
  89             self.terminal = 1
  90
  91         self.processors[type] = processor[0].content
  92         self.arguments[type] = p.xpathEval('//rule')
  93
  94         p.xpathFreeContext()
  95
  96
  97     def wrap_rspec (self, type, rspec):
  98         argument = self.arguments[type]
  99         p = rspec.xmldoc.xpathNewContext()
 100         root_node = p.xpathEval('/RSpec')
 101         if (not root_node or not root_node):
 102             raise Exception('An evil aggregate manager sent me a malformed RSpec. Please see the stack trace to identify it.')
 103
 104         root_node.addChild(arguments[type])
 105         return rspec
 106
 107     def __init__(self, chain=None, rule_number=None):
 108         self.rule_number = None
 109         self.chain = None
 110         self.xmldoc = None
 111         self.terminal = 0
 112         self.final_processor = '__sfatables_rule_wrap_up__.xsl'
 113
 114         self.arguments = {'match':None,'target':None}
 115         self.processors = {'match':None,'target':None}
 116         self.context = {'match':None,'target':None}
 117
 118         if (chain and rule_number):
 119             self.load_xml_extension('match', chain, rule_number)
 120             self.load_xml_extension('target',chain, rule_number)
 121             self.rule_number = rule_number
 122             self.chain = chain
 123         return
 124
 125     def free(self):
 126         self.xmldoc.freeDoc()