sfatables/xmlrule.py

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