# 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 List, Generator, Iterable

from volatility.framework import constants, exceptions, renderers
from volatility.framework import interfaces
from volatility.framework.configuration import requirements
from volatility.framework.renderers import format_hints
from volatility.framework.symbols import intermed
from volatility.framework.symbols.windows.extensions import pe
from volatility.plugins.windows import pslist, modules

vollog = logging.getLogger(__name__)


class ModDump(interfaces.plugins.PluginInterface):
    """Dumps kernel modules."""

    _version = (1, 0, 0)

    @classmethod
    def get_requirements(cls) -> List[interfaces.configuration.RequirementInterface]:
        # Reuse the requirements from the plugins we use
        return [
            requirements.PluginRequirement(name = 'pslist', plugin = pslist.PsList, version = (1, 0, 0)),
            requirements.PluginRequirement(name = 'modules', plugin = modules.Modules, version = (1, 0, 0)),
            requirements.TranslationLayerRequirement(name = 'primary',
                                                     description = 'Memory layer for the kernel',
                                                     architectures = ["Intel32", "Intel64"]),
            requirements.SymbolTableRequirement(name = "nt_symbols", description = "Windows kernel symbols")
        ]

    @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 = []  # type: 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, mods):

        session_layers = list(self.get_session_layers(self.context, self.config['primary'], self.config['nt_symbols']))
        pe_table_name = intermed.IntermediateSymbolTable.create(self.context,
                                                                self.config_path,
                                                                "windows",
                                                                "pe",
                                                                class_types = pe.class_types)

        for mod in mods:
            try:
                BaseDllName = mod.BaseDllName.get_string()
            except exceptions.InvalidAddressException:
                BaseDllName = renderers.UnreadableValue()

            session_layer_name = self.find_session_layer(self.context, session_layers, mod.DllBase)
            if session_layer_name is None:
                result_text = "Cannot find a viable session layer for {0:#x}".format(mod.DllBase)
            else:
                try:
                    dos_header = self.context.object(pe_table_name + constants.BANG + "_IMAGE_DOS_HEADER",
                                                     offset = mod.DllBase,
                                                     layer_name = session_layer_name)

                    filedata = interfaces.plugins.FileInterface("module.{0:#x}.dmp".format(mod.DllBase))

                    for offset, data in dos_header.reconstruct():
                        filedata.data.seek(offset)
                        filedata.data.write(data)

                    self.produce_file(filedata)
                    result_text = "Stored {}".format(filedata.preferred_filename)

                except ValueError:
                    result_text = "PE parsing error"

                except exceptions.SwappedInvalidAddressException as exp:
                    result_text = "Required memory at {0:#x} is inaccessible (swapped)".format(exp.invalid_address)

                except exceptions.InvalidAddressException as exp:
                    result_text = "Required memory at {0:#x} is not valid".format(exp.invalid_address)

            yield (0, (format_hints.Hex(mod.DllBase), BaseDllName, result_text))

    def run(self):
        return renderers.TreeGrid([("Base", format_hints.Hex), ("Name", str), ("Result", str)],
                                  self._generator(
                                      modules.Modules.list_modules(context = self.context,
                                                                   layer_name = self.config['primary'],
                                                                   symbol_table = self.config['nt_symbols'])))