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|
use std::fmt;
use std::hash::{Hash, Hasher};
/// Describes features supported by an OpenPGP implementation.
#[derive(Clone)]
pub struct Features{
mdc: bool,
aead: bool,
unknown: Box<[u8]>,
/// Original length, including trailing zeros.
pad_to: usize,
}
impl Default for Features {
fn default() -> Self {
Features{
mdc: false,
aead: false,
unknown: Default::default(),
pad_to: 0,
}
}
}
impl fmt::Debug for Features {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let mut dirty = false;
if self.supports_mdc() {
f.write_str("MDC")?;
dirty = true;
}
if self.supports_aead() {
if dirty { f.write_str(", ")?; }
f.write_str("AEAD")?;
dirty = true;
}
if ! self.unknown.is_empty() {
if dirty { f.write_str(", ")?; }
f.write_str("+0x")?;
f.write_str(
&crate::fmt::hex::encode_pretty(&self.unknown))?;
dirty = true;
}
if self.pad_to > FEATURE_FLAGS_N_KNOWN_BYTES + self.unknown.len() {
if dirty { f.write_str(", ")?; }
write!(f, "+padding({} bytes)", self.pad_to - self.unknown.len())?;
}
Ok(())
}
}
impl PartialEq for Features {
fn eq(&self, other: &Self) -> bool {
self.mdc == other.mdc
&& self.aead == other.aead
&& self.unknown == other.unknown
}
}
impl Eq for Features {}
impl Hash for Features {
fn hash<H: Hasher>(&self, state: &mut H) {
self.mdc.hash(state);
self.aead.hash(state);
self.unknown.hash(state);
}
}
impl Features {
/// Creates a new instance from `bits`.
pub fn new<B: AsRef<[u8]>>(bits: B) -> Self {
let bits = bits.as_ref();
let mut pad_to = 0;
let mdc = bits.get(0)
.map(|x| x & FEATURE_FLAG_MDC != 0).unwrap_or(false);
let aead = bits.get(0)
.map(|x| x & FEATURE_FLAG_AEAD != 0).unwrap_or(false);
let unk = if bits.is_empty() {
Box::default()
} else {
let mut cpy = Vec::from(bits);
cpy[0] &= (FEATURE_FLAG_MDC | FEATURE_FLAG_AEAD) ^ 0xff;
pad_to = crate::types::bitfield_remove_padding(&mut cpy);
cpy.into_boxed_slice()
};
Features{
mdc: mdc, aead: aead, unknown: unk, pad_to,
}
}
/// Returns an feature set describing Sequoia.
pub fn sequoia() -> Self {
Features{
mdc: true,
aead: false,
unknown: Default::default(),
pad_to: 0,
}
}
/// Returns a slice referencing the raw values.
pub(crate) fn to_vec(&self) -> Vec<u8> {
let mut ret = if self.unknown.is_empty() {
vec![0]
} else {
self.unknown.clone().into()
};
if self.mdc { ret[0] |= FEATURE_FLAG_MDC; }
if self.aead { ret[0] |= FEATURE_FLAG_AEAD; }
// Corner case: empty flag field. We initialized ret to
// vec![0] for easy setting of flags. See if any of the above
// was set.
if ret.len() == 1 && ret[0] == 0 {
// Nope. Trim this byte.
ret.pop();
}
for _ in ret.len()..self.pad_to {
ret.push(0);
}
ret
}
/// Whether or not MDC is supported.
pub fn supports_mdc(&self) -> bool {
self.mdc
}
/// Sets whether or not MDC is supported.
pub fn set_mdc(mut self, v: bool) -> Self {
self.mdc = v;
self
}
/// Whether or not AEAD is supported.
pub fn supports_aead(&self) -> bool {
self.aead
}
/// Sets whether or not AEAD is supported.
pub fn set_aead(mut self, v: bool) -> Self {
self.aead = v;
self
}
}
/// Modification Detection (packets 18 and 19).
const FEATURE_FLAG_MDC: u8 = 0x01;
/// AEAD Encrypted Data Packet (packet 20) and version 5 Symmetric-Key
/// Encrypted Session Key Packets (packet 3).
const FEATURE_FLAG_AEAD: u8 = 0x02;
/// Number of bytes with known flags.
const FEATURE_FLAGS_N_KNOWN_BYTES: usize = 1;
#[cfg(test)]
mod tests {
use super::*;
quickcheck! {
fn roundtrip(raw: Vec<u8>) -> bool {
let val = Features::new(&raw);
assert_eq!(raw, val.to_vec());
// Check that equality ignores padding.
let mut val_without_padding = val.clone();
val_without_padding.pad_to = val.unknown.len();
assert_eq!(val, val_without_padding);
true
}
}
}
|
