# This file is Copyright 2019 Volatility Foundation and licensed under the Volatility Software License 1.0
# which is available at https://www.volatilityfoundation.org/license/vsl-v1.0
#

import datetime
from typing import Iterable

from volatility.framework import renderers, exceptions, interfaces
from volatility.framework.configuration import requirements
from volatility.framework.renderers import format_hints
from volatility.plugins import timeliner
from volatility.plugins.windows import poolscanner


class SymlinkScan(interfaces.plugins.PluginInterface, timeliner.TimeLinerInterface):
    """Scans for links present in a particular windows memory image."""

    @classmethod
    def get_requirements(cls):
        return [
            requirements.TranslationLayerRequirement(name = 'primary',
                                                     description = 'Memory layer for the kernel',
                                                     architectures = ["Intel32", "Intel64"]),
            requirements.SymbolTableRequirement(name = "nt_symbols", description = "Windows kernel symbols"),
        ]

    @classmethod
    def scan_symlinks(cls,
                      context: interfaces.context.ContextInterface,
                      layer_name: str,
                      symbol_table: str) -> \
            Iterable[interfaces.objects.ObjectInterface]:
        """Scans for links using the poolscanner module and constraints.

        Args:
            context: The context to retrieve required elements (layers, symbol tables) from
            layer_name: The name of the layer on which to operate
            symbol_table: The name of the table containing the kernel symbols

        Returns:
            A list of symlink objects found by scanning memory for the Symlink pool signatures
        """

        constraints = poolscanner.PoolScanner.builtin_constraints(symbol_table, [b'Sym\xe2', b'Symb'])

        for result in poolscanner.PoolScanner.generate_pool_scan(context, layer_name, symbol_table, constraints):

            _constraint, mem_object, _header = result
            yield mem_object

    def _generator(self):
        for link in self.scan_symlinks(self.context, self.config['primary'], self.config['nt_symbols']):

            try:
                from_name = link.get_link_name()
            except exceptions.InvalidAddressException:
                continue

            try:
                to_name = link.LinkTarget.String
            except exceptions.InvalidAddressException:
                continue

            yield (0, (format_hints.Hex(link.vol.offset), link.get_create_time(), from_name, to_name))

    def generate_timeline(self):
        for row in self._generator():
            _depth, row_data = row
            description = "Symlink: {} -> {}".format(row_data[2], row_data[3])
            yield (description, timeliner.TimeLinerType.CREATED, row_data[1])

    def run(self):
        return renderers.TreeGrid([
            ("Offset", format_hints.Hex),
            ("CreateTime", datetime.datetime),
            ("From Name", str),
            ("To Name", str),
        ], self._generator())