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//! Dealing with state names and their properties
#![deny(unsafe_code)]
use std::fmt::{self, Binary, Display, Formatter, LowerHex, Octal, UpperHex};
use num_traits::FromPrimitive;
use thiserror::Error;
/// The magic number for converting between opaque and transparent values of state names
///
/// For reference, see e.g. <https://blog.quarkslab.com/playing-with-the-windows-notification-facility-wnf.html>
const STATE_NAME_XOR_KEY: u64 = 0x41C6_4E6D_A3BC_0074;
/// The lifetime of a state
///
/// This property of a state controls at what point in time it is automatically deleted as well as if and how it is
/// persisted.
#[derive(Clone, Copy, Debug, Eq, FromPrimitive, Hash, PartialEq)]
#[repr(u8)]
pub enum StateLifetime {
/// Lifetime of a *well-known* state
///
/// A state with this lifetime cannot be created or deleted through the WNF API, but instead is provisioned with
/// the system. It lives forever.
///
/// It is persisted in the Windows registry under the key
/// `HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Notifications`
WellKnown = 0,
/// Lifetime of a *permanent* state
///
/// A state with this lifetime can be created and deleted through the WNF API at any time and is never deleted
/// automatically.
///
/// Creating a state with this lifetime requires the `SeCreatePermanentPrivilege` privilege.
///
/// It is persisted in the Windows registry under the key
/// `HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Notifications`
Permanent = 1,
/// Lifetime of a *persistent* state (also known as *volatile*)
///
/// A state with this lifetime can be created and deleted through the WNF API at any time and is automatically
/// deleted on system reboot.
///
/// Creating a state with this lifetime requires the `SeCreatePermanentPrivilege` privilege.
///
/// The name "persistent" is meant in relation to a temporary state name because it is persisted beyond the
/// lifetime of the process it was created from. The alternative name "volatile" is meant in relation to a
/// permanent state name because it is deleted on system reboot.
///
/// It is persisted in the Windows registry under the key
/// `HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\VolatileNotifications`
Persistent = 2,
/// Lifetime of a *temporary* state
///
/// A state with this lifetime can be created and deleted through the WNF API at any time and is automatically
/// deleted when the process it was created from exits.
///
/// It is not persisted in the Windows registry.
Temporary = 3,
}
/// The data scope of a state
///
/// This property of a state controls whether it maintains multiple instances of its data that are scoped in different
/// ways.
#[derive(Clone, Copy, Debug, Eq, FromPrimitive, Hash, PartialEq)]
#[repr(u8)]
pub enum DataScope {
/// *System* data scope
System = 0,
/// *Session* data scope
Session = 1,
/// *User* data scope
User = 2,
/// *Process* data scope
Process = 3,
/// *Machine* data scope
///
/// This seems to be the widest available data scope that all reverse engineering resources agree on. It is a good
/// default choice if you don't care about data scope.
Machine = 4,
/// *Physical Machine* data scope
///
/// This is only mentioned by some reverse engineering resources, not all of them. However, there exist
/// (well-known) state names with this data scope.
PhysicalMachine = 5,
}
/// The descriptor of a state name
///
/// This contains the properties of a [`StateName`] that are encoded in the bits of its transparent value.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct StateNameDescriptor {
/// WNF version number, currently always `1`
pub version: u8,
/// Lifetime of the state name
pub lifetime: StateLifetime,
/// Data scope of the state name
pub data_scope: DataScope,
/// Whether the state data (not the state name itself) are persisted across system reboots
///
/// This only applies to state names with the [`StateLifetime::WellKnown`] or
/// [`StateLifetime::Permanent`] lifetimes. It is always `false` for state names with other lifetimes.
pub is_permanent: bool,
/// Unique sequence number of the state name
pub unique_id: u32,
/// Owner tag of the state name
///
/// This only applies to state names with the [`StateLifetime::WellKnown`] lifetime. It is always `0` for
/// state names with other lifetimes.
pub owner_tag: u32,
}
/// A state name
///
/// A state name is usually represented by its "opaque value", which is a 64-bit integer. This opaque value can be
/// converted to a "transparent" value by XOR'ing with the magic number `0x41C64E6DA3BC0074`. This transparent value
/// encodes certain properties of the state name in its bits. The set of these properties is represented by the
/// [`StateNameDescriptor`] type. Use the provided [`TryFrom`]/[`TryInto`] implementations to convert between a
/// [`StateName`] (represented by its opaque value) and the corresponding [`StateNameDescriptor`].
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct StateName {
opaque_value: u64,
}
impl StateName {
/// Creates a [`StateName`] from the given opaque value
pub const fn from_opaque_value(opaque_value: u64) -> Self {
Self { opaque_value }
}
/// Returns the opaque value of this [`StateName`]
pub const fn opaque_value(self) -> u64 {
self.opaque_value
}
}
impl From<u64> for StateName {
fn from(opaque_value: u64) -> Self {
Self::from_opaque_value(opaque_value)
}
}
impl From<StateName> for u64 {
fn from(state_name: StateName) -> Self {
state_name.opaque_value()
}
}
impl PartialEq<u64> for StateName {
fn eq(&self, other: &u64) -> bool {
self.opaque_value == *other
}
}
impl PartialEq<StateName> for u64 {
fn eq(&self, other: &StateName) -> bool {
*self == other.opaque_value
}
}
impl Display for StateName {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
write!(f, "{self:X}")
}
}
impl UpperHex for StateName {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
write!(f, "{:#018X}", self.opaque_value)
}
}
impl LowerHex for StateName {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
write!(f, "{:#018x}", self.opaque_value)
}
}
impl Octal for StateName {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
write!(f, "{:#024o}", self.opaque_value)
}
}
impl Binary for StateName {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
write!(f, "{:#066b}", self.opaque_value)
}
}
impl TryFrom<StateNameDescriptor> for StateName {
type Error = StateNameFromDescriptorError;
fn try_from(descriptor: StateNameDescriptor) -> Result<Self, Self::Error> {
if descriptor.version >= (1 << 4) {
return Err(StateNameFromDescriptorError::InvalidVersion(descriptor.version));
}
if descriptor.unique_id >= (1 << 21) {
return Err(StateNameFromDescriptorError::InvalidUniqueId(descriptor.unique_id));
}
let transparent_value = u64::from(descriptor.version)
+ ((descriptor.lifetime as u64) << 4)
+ ((descriptor.data_scope as u64) << 6)
+ ((u64::from(descriptor.is_permanent)) << 10)
+ ((u64::from(descriptor.unique_id)) << 11)
+ ((u64::from(descriptor.owner_tag)) << 32);
let opaque_value = transparent_value ^ STATE_NAME_XOR_KEY;
Ok(Self { opaque_value })
}
}
impl TryFrom<StateName> for StateNameDescriptor {
type Error = StateNameDescriptorFromStateNameError;
fn try_from(state_name: StateName) -> Result<Self, Self::Error> {
let transparent_value = state_name.opaque_value ^ STATE_NAME_XOR_KEY;
let lifetime_value = ((transparent_value >> 4) & 0b11) as u8;
let data_scope_value = ((transparent_value >> 6) & 0b1111) as u8;
Ok(Self {
version: (transparent_value & 0b1111) as u8,
// Since `lifetime_value <= 3`, this always succeeds
lifetime: StateLifetime::from_u8(lifetime_value).unwrap(),
data_scope: DataScope::from_u8(data_scope_value).ok_or(
StateNameDescriptorFromStateNameError::InvalidDataScope(data_scope_value),
)?,
is_permanent: transparent_value & (1 << 10) != 0,
unique_id: ((transparent_value >> 11) & 0x001F_FFFF) as u32,
owner_tag: (transparent_value >> 32) as u32,
})
}
}
/// An error converting a [`StateNameDescriptor`] into a [`StateName`]
#[derive(Clone, Copy, Debug, Error, Eq, Hash, PartialEq)]
pub enum StateNameFromDescriptorError {
/// The [`StateNameDescriptor::version`] is invalid (must be less than `2^4`)
#[error("invalid version: {0}")]
InvalidVersion(u8),
/// The [`StateNameDescriptor::unique_id`] is invalid (must be less than `2^21`)
#[error("invalid unique id: {0}")]
InvalidUniqueId(u32),
}
/// An error converting a [`StateName`] into a [`StateNameDescriptor`]
#[derive(Clone, Copy, Debug, Error, Eq, Hash, PartialEq)]
pub enum StateNameDescriptorFromStateNameError {
/// The data scope encoded in the state name is invalid (must be in `0..=5`)
#[error("invalid data scope: {0}")]
InvalidDataScope(u8),
}
#[cfg(test)]
mod tests {
use super::*;
const SAMPLE_STATE_NAME: StateName = StateName::from_opaque_value(0x0D83_063E_A3BE_5075);
const SAMPLE_DESCRIPTOR: StateNameDescriptor = StateNameDescriptor {
version: 1,
lifetime: StateLifetime::WellKnown,
data_scope: DataScope::System,
is_permanent: false,
unique_id: 0x0000_004A,
owner_tag: 0x4C45_4853,
};
#[test]
fn state_name_into_descriptor_success() {
let result: Result<StateNameDescriptor, _> = SAMPLE_STATE_NAME.try_into();
assert_eq!(result, Ok(SAMPLE_DESCRIPTOR));
}
#[test]
fn state_name_into_descriptor_invalid_data_scope() {
let opaque_value = 0x0D83_063E_A3BE_51F5; // this is `SAMPLE_STATE_NAME` with data scope set to 0x06
let result: Result<StateNameDescriptor, _> = StateName::from_opaque_value(opaque_value).try_into();
assert_eq!(
result,
Err(StateNameDescriptorFromStateNameError::InvalidDataScope(0x06))
);
}
#[test]
fn descriptor_into_state_name_success() {
let result: Result<StateName, _> = SAMPLE_DESCRIPTOR.try_into();
assert_eq!(result, Ok(SAMPLE_STATE_NAME));
}
#[test]
fn descriptor_into_state_name_invalid_version() {
let descriptor = StateNameDescriptor {
version: 1 << 4,
..SAMPLE_DESCRIPTOR
};
let result: Result<StateName, _> = descriptor.try_into();
assert_eq!(result, Err(StateNameFromDescriptorError::InvalidVersion(1 << 4)));
}
#[test]
fn descriptor_into_state_name_invalid_unique_id() {
let descriptor = StateNameDescriptor {
unique_id: 1 << 21,
..SAMPLE_DESCRIPTOR
};
let result: Result<StateName, _> = descriptor.try_into();
assert_eq!(result, Err(StateNameFromDescriptorError::InvalidUniqueId(1 << 21)));
}
#[test]
fn state_name_display() {
assert_eq!(SAMPLE_STATE_NAME.to_string(), "0x0D83063EA3BE5075");
}
#[test]
fn state_name_upper_hex() {
assert_eq!(format!("{SAMPLE_STATE_NAME:X}"), "0x0D83063EA3BE5075");
}
#[test]
fn state_name_lower_hex() {
assert_eq!(format!("{SAMPLE_STATE_NAME:x}"), "0x0d83063ea3be5075");
}
#[test]
fn state_name_octal() {
assert_eq!(format!("{SAMPLE_STATE_NAME:o}"), "0o0066030143724357450165");
}
#[test]
fn state_name_binary() {
assert_eq!(
format!("{SAMPLE_STATE_NAME:b}"),
"0b0000110110000011000001100011111010100011101111100101000001110101"
);
}
}