sfatables/xmlrule.py

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