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