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