# 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 logging
from typing import Iterable, List, Generator

from volatility3.framework import renderers, interfaces, exceptions, constants
from volatility3.framework.configuration import requirements
from volatility3.framework.renderers import format_hints
from volatility3.framework.symbols import intermed
from volatility3.framework.symbols.windows.extensions import pe
from volatility3.plugins.windows import poolscanner, dlllist, pslist

vollog = logging.getLogger(__name__)


class ModScan(interfaces.plugins.PluginInterface):
    """Scans for modules present in a particular windows memory image."""

    _required_framework_version = (2, 0, 0)
    _version = (1, 0, 0)

    @classmethod
    def get_requirements(cls):
        return [
            requirements.ModuleRequirement(name = 'kernel', description = 'Windows kernel',
                                                     architectures = ["Intel32", "Intel64"]),
            requirements.VersionRequirement(name = 'poolerscanner',
                                            component = poolscanner.PoolScanner,
                                            version = (1, 0, 0)),
            requirements.VersionRequirement(name = 'pslist', component = pslist.PsList, version = (2, 0, 0)),
            requirements.VersionRequirement(name = 'dlllist', component = dlllist.DllList, version = (2, 0, 0)),
            requirements.BooleanRequirement(name = 'dump',
                                            description = "Extract listed modules",
                                            default = False,
                                            optional = True)
        ]

    @classmethod
    def scan_modules(cls,
                     context: interfaces.context.ContextInterface,
                     layer_name: str,
                     symbol_table: str) -> \
            Iterable[interfaces.objects.ObjectInterface]:
        """Scans for modules 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 Driver objects as found from the `layer_name` layer based on Driver pool signatures
        """

        constraints = poolscanner.PoolScanner.builtin_constraints(symbol_table, [b'MmLd'])

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

            _constraint, mem_object, _header = result
            yield mem_object

    @classmethod
    def get_session_layers(cls,
                           context: interfaces.context.ContextInterface,
                           layer_name: str,
                           symbol_table: str,
                           pids: List[int] = None) -> Generator[str, None, None]:
        """Build a cache of possible virtual layers, in priority starting with
        the primary/kernel layer. Then keep one layer per session by cycling
        through the process list.

        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
            pids: A list of process identifiers to include exclusively or None for no filter

        Returns:
            A list of session layer names
        """
        seen_ids: List[interfaces.objects.ObjectInterface] = []
        filter_func = pslist.PsList.create_pid_filter(pids or [])

        for proc in pslist.PsList.list_processes(context = context,
                                                 layer_name = layer_name,
                                                 symbol_table = symbol_table,
                                                 filter_func = filter_func):
            proc_id = "Unknown"
            try:
                proc_id = proc.UniqueProcessId
                proc_layer_name = proc.add_process_layer()

                # create the session space object in the process' own layer.
                # not all processes have a valid session pointer.
                session_space = context.object(symbol_table + constants.BANG + "_MM_SESSION_SPACE",
                                               layer_name = layer_name,
                                               offset = proc.Session)

                if session_space.SessionId in seen_ids:
                    continue

            except exceptions.InvalidAddressException:
                vollog.log(
                    constants.LOGLEVEL_VVV,
                    "Process {} does not have a valid Session or a layer could not be constructed for it".format(
                        proc_id))
                continue

            # save the layer if we haven't seen the session yet
            seen_ids.append(session_space.SessionId)
            yield proc_layer_name

    @classmethod
    def find_session_layer(cls, context: interfaces.context.ContextInterface, session_layers: Iterable[str],
                           base_address: int):
        """Given a base address and a list of layer names, find a layer that
        can access the specified address.

        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
            session_layers: A list of session layer names
            base_address: The base address to identify the layers that can access it

        Returns:
            Layer name or None if no layers that contain the base address can be found
        """

        for layer_name in session_layers:
            if context.layers[layer_name].is_valid(base_address):
                return layer_name

        return None

    def _generator(self):
        kernel = self.context.modules[self.config['kernel']]

        session_layers = list(self.get_session_layers(self.context, kernel.layer_name, kernel.symbol_table_name))
        pe_table_name = intermed.IntermediateSymbolTable.create(self.context,
                                                                self.config_path,
                                                                "windows",
                                                                "pe",
                                                                class_types = pe.class_types)

        for mod in self.scan_modules(self.context, kernel.layer_name, kernel.symbol_table_name):

            try:
                BaseDllName = mod.BaseDllName.get_string()
            except exceptions.InvalidAddressException:
                BaseDllName = ""

            try:
                FullDllName = mod.FullDllName.get_string()
            except exceptions.InvalidAddressException:
                FullDllName = ""

            file_output = "Disabled"
            if self.config['dump']:

                session_layer_name = self.find_session_layer(self.context, session_layers, mod.DllBase)
                file_output = f"Cannot find a viable session layer for {mod.DllBase:#x}"
                if session_layer_name:
                    file_handle = dlllist.DllList.dump_pe(self.context,
                                                          pe_table_name,
                                                          mod,
                                                          self.open,
                                                          layer_name = session_layer_name)
                    file_output = "Error outputting file"
                    if file_handle:
                        file_output = file_handle.preferred_filename

            yield (0, (format_hints.Hex(mod.vol.offset), format_hints.Hex(mod.DllBase),
                       format_hints.Hex(mod.SizeOfImage), BaseDllName, FullDllName, file_output))

    def run(self):
        return renderers.TreeGrid([("Offset", format_hints.Hex), ("Base", format_hints.Hex), ("Size", format_hints.Hex),
                                   ("Name", str), ("Path", str), ("File output", str)], self._generator())
