# This file was contributed to the Volatility Framework Version 3.
# Copyright (C) 2018 Volatility Foundation.
#
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import logging
from typing import Iterable, List, Tuple

from volatility.framework import interfaces, renderers
from volatility.framework.configuration import requirements
from volatility.framework.layers import resources
from volatility.framework.renderers import format_hints
from volatility.plugins import yarascan
from volatility.plugins.windows import pslist

vollog = logging.getLogger(__name__)

try:
    import yara
except ImportError:
    vollog.info("Python Yara module not found, plugin (and dependent plugins) not available")


class VadYaraScan(interfaces.plugins.PluginInterface):

    @classmethod
    def get_requirements(cls) -> List[interfaces.configuration.RequirementInterface]:
        return [
            requirements.TranslationLayerRequirement(
                name = 'primary', description = "Memory layer for the kernel", architectures = ["Intel32", "Intel64"]),
            requirements.SymbolTableRequirement(name = "nt_symbols", description = "Windows kernel symbols"),
            requirements.BooleanRequirement(
                name = "wide", description = "Match wide (unicode) strings", default = False, optional = True),
            requirements.StringRequirement(
                name = "yara_rules", description = "Yara rules (as a string)", optional = True),
            requirements.URIRequirement(name = "yara_file", description = "Yara rules (as a file)", optional = True),
            requirements.IntRequirement(
                name = "max_size",
                default = 0x40000000,
                description = "Set the maximum size (default is 1GB)",
                optional = True)
        ] + pslist.PsList.list_processes_filter_requirements

    def _generator(self):

        layer = self.context.layers[self.config['primary']]
        rules = None
        if self.config.get('yara_rules', None) is not None:
            rule = self.config['yara_rules']
            if rule[0] not in ["{", "/"]:
                rule = '"{}"'.format(rule)
            if self.config.get('case', False):
                rule += " nocase"
            if self.config.get('wide', False):
                rule += " wide ascii"
            rules = yara.compile(sources = {'n': 'rule r1 {{strings: $a = {} condition: $a}}'.format(rule)})
        elif self.config.get('yara_file', None) is not None:
            rules = yara.compile(file = resources.ResourceAccessor().open(self.config['yara_file'], "rb"))
        else:
            vollog.error("No yara rules, nor yara rules file were specified")

        filter_func = pslist.PsList.create_pid_filter([self.config.get('pid', None)])

        for task in pslist.PsList.list_processes(
                context = self.context,
                layer_name = self.config['primary'],
                symbol_table = self.config['nt_symbols'],
                filter_func = filter_func):
            for offset, name in layer.scan(
                    context = self.context,
                    scanner = yarascan.YaraScanner(rules = rules),
                    sections = self.get_vad_maps(task)):
                yield format_hints.Hex(offset), name

    @staticmethod
    def get_vad_maps(task: interfaces.objects.ObjectInterface) -> Iterable[Tuple[int, int]]:

        vad_root = task.get_vad_root()
        for vad in vad_root.traverse():
            end = vad.get_end()
            start = vad.get_start()
            yield (start, end - start)

    def run(self):
        return renderers.TreeGrid([('Offset', format_hints.Hex), ('Rule', str)], self._generator())