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