sfatables/xmlrule.py

   1 import libxml2
   2 import libxslt
   3 from sfatables.globals import *
   4
   5 class XMLRule:
   6     def apply_processor(self, type, doc, output_xpath_filter=None):
   7         processor = self.processors[type]
   8
   9         # XXX TO CLEAN UP
  10         filepath = os.path.join(sfatables_config, 'processors', processor)
  11         # XXX
  12
  13         print filepath
  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             raise Exception('Could not find final rule filter')
  39
  40         styledoc = libxml2.parseFile(filepath)
  41         style = libxslt.parseStylesheetDoc(styledoc)
  42         result = style.applyStylesheet(doc, None)
  43         stylesheet_result = result#style.saveResultToString(result)
  44         style.freeStylesheet()
  45         #doc.freeDoc()
  46         #result.freeDoc()
  47
  48         return stylesheet_result
  49
  50     def match(self, rspec):
  51         match_result = self.apply_processor('match',rspec,"//result/@verdict")
  52         return (match_result[0].content=='True')
  53
  54     def target(self, rspec):
  55         target_result = self.apply_processor('target',rspec,None)
  56         return target_result
  57
  58     def add_rule_context_to_rspec(self, doc):
  59         p = doc.xpathNewContext()
  60         context = p.xpathEval("//rspec")
  61         if (not context):
  62             raise Exception('Request is not an rspec')
  63         else:
  64             # Add the request context
  65             matchNode = libxml2.newNode('match-context')
  66             matchNode.addChild(self.arguments['match'])
  67             targetNode = libxml2.newNode('target-context')
  68             targetNode.addChild(self.arguments['target'])
  69             context[0].addChild(matchNode)
  70             context[0].addChild(targetNode)
  71         p.xpathFreeContext()
  72
  73         return doc
  74
  75     def apply_interpreted(self, rspec):
  76         self.add_rule_context_to_rspec(rspec)
  77         # Interpreted
  78         #
  79         # output =
  80         #    if (match(match_args, rspec)
  81         #       then target(target_args, rspec)
  82         #       else rspec
  83
  84         if (self.match(rspec)):
  85             return self.wrap_up(self.target(rspec))
  86         else:
  87             return self.wrap_up(rspec)
  88
  89
  90     def apply_compiled(rspec):
  91         # Not supported yet
  92         return None
  93
  94     def load_xml_extension (self, type, chain, rule_number):
  95         filename = sfatables_config+"/"+chain+"/"+"sfatables-%d-%s"%(rule_number,type)
  96
  97         self.xmldoc = libxml2.parseFile(filename)
  98         p = self.xmldoc.xpathNewContext()
  99
 100         context = p.xpathEval('//context/@select')
 101         self.context[type] = context[0].content
 102
 103         processor = p.xpathEval('//processor/@filename')
 104
 105         context = p.xpathEval('//attributes/attribute[@terminal="yes"]')
 106         if (context != []):
 107             self.terminal = 1
 108
 109         self.processors[type] = processor[0].content
 110         self.arguments[type] = p.xpathEval('//rule')
 111
 112         p.xpathFreeContext()
 113
 114
 115     def wrap_rspec (self, type, rspec):
 116         argument = self.arguments[type]
 117         p = rspec.xmldoc.xpathNewContext()
 118         root_node = p.xpathEval('/RSpec')
 119         if (not root_node or not root_node):
 120             raise Exception('An evil aggregate manager sent me a malformed RSpec. Please see the stack trace to identify it.')
 121
 122         root_node.addChild(arguments[type])
 123         return rspec
 124
 125     def __init__(self, chain=None, rule_number=None):
 126         self.rule_number = None
 127         self.chain = None
 128         self.xmldoc = None
 129         self.terminal = 0
 130         self.final_processor = '__sfatables_rule_wrap_up__.xsl'
 131
 132         self.arguments = {'match':None,'target':None}
 133         self.processors = {'match':None,'target':None}
 134         self.context = {'match':None,'target':None}
 135
 136         if (chain and rule_number):
 137             self.load_xml_extension('match', chain, rule_number)
 138             self.load_xml_extension('target',chain, rule_number)
 139             self.rule_number = rule_number
 140             self.chain = chain
 141         return
 142
 143     def free(self):
 144         self.xmldoc.freeDoc()