1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395
//! An implementation of SipHash.
#![allow(deprecated)] // the types in this module are deprecated
use crate::cmp;
use crate::marker::PhantomData;
use crate::mem;
use crate::ptr;
/// An implementation of SipHash 1-3.
///
/// This is currently the default hashing function used by standard library
/// (e.g., `collections::HashMap` uses it by default).
///
/// See: <https://131002.net/siphash>
#[unstable(feature = "hashmap_internals", issue = "none")]
#[deprecated(since = "1.13.0", note = "use `std::hash::DefaultHasher` instead")]
#[derive(Debug, Clone, Default)]
#[doc(hidden)]
pub struct SipHasher13 {
hasher: Hasher<Sip13Rounds>,
}
/// An implementation of SipHash 2-4.
///
/// See: <https://131002.net/siphash/>
#[unstable(feature = "hashmap_internals", issue = "none")]
#[deprecated(since = "1.13.0", note = "use `std::hash::DefaultHasher` instead")]
#[derive(Debug, Clone, Default)]
struct SipHasher24 {
hasher: Hasher<Sip24Rounds>,
}
/// An implementation of SipHash 2-4.
///
/// See: <https://131002.net/siphash/>
///
/// SipHash is a general-purpose hashing function: it runs at a good
/// speed (competitive with Spooky and City) and permits strong _keyed_
/// hashing. This lets you key your hash tables from a strong RNG, such as
/// [`rand::os::OsRng`](https://docs.rs/rand/latest/rand/rngs/struct.OsRng.html).
///
/// Although the SipHash algorithm is considered to be generally strong,
/// it is not intended for cryptographic purposes. As such, all
/// cryptographic uses of this implementation are _strongly discouraged_.
#[stable(feature = "rust1", since = "1.0.0")]
#[deprecated(since = "1.13.0", note = "use `std::hash::DefaultHasher` instead")]
#[derive(Debug, Clone, Default)]
pub struct SipHasher(SipHasher24);
#[derive(Debug)]
struct Hasher<S: Sip> {
k0: u64,
k1: u64,
length: usize, // how many bytes we've processed
state: State, // hash State
tail: u64, // unprocessed bytes le
ntail: usize, // how many bytes in tail are valid
_marker: PhantomData<S>,
}
#[derive(Debug, Clone, Copy)]
#[repr(C)]
struct State {
// v0, v2 and v1, v3 show up in pairs in the algorithm,
// and simd implementations of SipHash will use vectors
// of v02 and v13. By placing them in this order in the struct,
// the compiler can pick up on just a few simd optimizations by itself.
v0: u64,
v2: u64,
v1: u64,
v3: u64,
}
macro_rules! compress {
($state:expr) => {{ compress!($state.v0, $state.v1, $state.v2, $state.v3) }};
($v0:expr, $v1:expr, $v2:expr, $v3:expr) => {{
$v0 = $v0.wrapping_add($v1);
$v2 = $v2.wrapping_add($v3);
$v1 = $v1.rotate_left(13);
$v1 ^= $v0;
$v3 = $v3.rotate_left(16);
$v3 ^= $v2;
$v0 = $v0.rotate_left(32);
$v2 = $v2.wrapping_add($v1);
$v0 = $v0.wrapping_add($v3);
$v1 = $v1.rotate_left(17);
$v1 ^= $v2;
$v3 = $v3.rotate_left(21);
$v3 ^= $v0;
$v2 = $v2.rotate_left(32);
}};
}
/// Loads an integer of the desired type from a byte stream, in LE order. Uses
/// `copy_nonoverlapping` to let the compiler generate the most efficient way
/// to load it from a possibly unaligned address.
///
/// Safety: this performs unchecked indexing of `$buf` at
/// `$i..$i+size_of::<$int_ty>()`, so that must be in-bounds.
macro_rules! load_int_le {
($buf:expr, $i:expr, $int_ty:ident) => {{
debug_assert!($i + mem::size_of::<$int_ty>() <= $buf.len());
let mut data = 0 as $int_ty;
ptr::copy_nonoverlapping(
$buf.as_ptr().add($i),
&mut data as *mut _ as *mut u8,
mem::size_of::<$int_ty>(),
);
data.to_le()
}};
}
/// Loads a u64 using up to 7 bytes of a byte slice. It looks clumsy but the
/// `copy_nonoverlapping` calls that occur (via `load_int_le!`) all have fixed
/// sizes and avoid calling `memcpy`, which is good for speed.
///
/// Safety: this performs unchecked indexing of `buf` at `start..start+len`, so
/// that must be in-bounds.
#[inline]
unsafe fn u8to64_le(buf: &[u8], start: usize, len: usize) -> u64 {
debug_assert!(len < 8);
let mut i = 0; // current byte index (from LSB) in the output u64
let mut out = 0;
if i + 3 < len {
// SAFETY: `i` cannot be greater than `len`, and the caller must guarantee
// that the index start..start+len is in bounds.
out = unsafe { load_int_le!(buf, start + i, u32) } as u64;
i += 4;
}
if i + 1 < len {
// SAFETY: same as above.
out |= (unsafe { load_int_le!(buf, start + i, u16) } as u64) << (i * 8);
i += 2
}
if i < len {
// SAFETY: same as above.
out |= (unsafe { *buf.get_unchecked(start + i) } as u64) << (i * 8);
i += 1;
}
//FIXME(fee1-dead): use debug_assert_eq
debug_assert!(i == len);
out
}
impl SipHasher {
/// Creates a new `SipHasher` with the two initial keys set to 0.
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
#[deprecated(since = "1.13.0", note = "use `std::hash::DefaultHasher` instead")]
#[rustc_const_unstable(feature = "const_hash", issue = "104061")]
#[must_use]
pub const fn new() -> SipHasher {
SipHasher::new_with_keys(0, 0)
}
/// Creates a `SipHasher` that is keyed off the provided keys.
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
#[deprecated(since = "1.13.0", note = "use `std::hash::DefaultHasher` instead")]
#[rustc_const_unstable(feature = "const_hash", issue = "104061")]
#[must_use]
pub const fn new_with_keys(key0: u64, key1: u64) -> SipHasher {
SipHasher(SipHasher24 { hasher: Hasher::new_with_keys(key0, key1) })
}
}
impl SipHasher13 {
/// Creates a new `SipHasher13` with the two initial keys set to 0.
#[inline]
#[unstable(feature = "hashmap_internals", issue = "none")]
#[deprecated(since = "1.13.0", note = "use `std::hash::DefaultHasher` instead")]
#[rustc_const_unstable(feature = "const_hash", issue = "104061")]
pub const fn new() -> SipHasher13 {
SipHasher13::new_with_keys(0, 0)
}
/// Creates a `SipHasher13` that is keyed off the provided keys.
#[inline]
#[unstable(feature = "hashmap_internals", issue = "none")]
#[deprecated(since = "1.13.0", note = "use `std::hash::DefaultHasher` instead")]
#[rustc_const_unstable(feature = "const_hash", issue = "104061")]
pub const fn new_with_keys(key0: u64, key1: u64) -> SipHasher13 {
SipHasher13 { hasher: Hasher::new_with_keys(key0, key1) }
}
}
impl<S: Sip> Hasher<S> {
#[inline]
const fn new_with_keys(key0: u64, key1: u64) -> Hasher<S> {
let mut state = Hasher {
k0: key0,
k1: key1,
length: 0,
state: State { v0: 0, v1: 0, v2: 0, v3: 0 },
tail: 0,
ntail: 0,
_marker: PhantomData,
};
state.reset();
state
}
#[inline]
const fn reset(&mut self) {
self.length = 0;
self.state.v0 = self.k0 ^ 0x736f6d6570736575;
self.state.v1 = self.k1 ^ 0x646f72616e646f6d;
self.state.v2 = self.k0 ^ 0x6c7967656e657261;
self.state.v3 = self.k1 ^ 0x7465646279746573;
self.ntail = 0;
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl super::Hasher for SipHasher {
#[inline]
fn write(&mut self, msg: &[u8]) {
self.0.hasher.write(msg)
}
#[inline]
fn write_str(&mut self, s: &str) {
self.0.hasher.write_str(s);
}
#[inline]
fn finish(&self) -> u64 {
self.0.hasher.finish()
}
}
#[unstable(feature = "hashmap_internals", issue = "none")]
impl super::Hasher for SipHasher13 {
#[inline]
fn write(&mut self, msg: &[u8]) {
self.hasher.write(msg)
}
#[inline]
fn write_str(&mut self, s: &str) {
self.hasher.write_str(s);
}
#[inline]
fn finish(&self) -> u64 {
self.hasher.finish()
}
}
impl<S: Sip> super::Hasher for Hasher<S> {
// Note: no integer hashing methods (`write_u*`, `write_i*`) are defined
// for this type. We could add them, copy the `short_write` implementation
// in librustc_data_structures/sip128.rs, and add `write_u*`/`write_i*`
// methods to `SipHasher`, `SipHasher13`, and `DefaultHasher`. This would
// greatly speed up integer hashing by those hashers, at the cost of
// slightly slowing down compile speeds on some benchmarks. See #69152 for
// details.
#[inline]
fn write(&mut self, msg: &[u8]) {
let length = msg.len();
self.length += length;
let mut needed = 0;
if self.ntail != 0 {
needed = 8 - self.ntail;
// SAFETY: `cmp::min(length, needed)` is guaranteed to not be over `length`
self.tail |= unsafe { u8to64_le(msg, 0, cmp::min(length, needed)) } << (8 * self.ntail);
if length < needed {
self.ntail += length;
return;
} else {
self.state.v3 ^= self.tail;
S::c_rounds(&mut self.state);
self.state.v0 ^= self.tail;
self.ntail = 0;
}
}
// Buffered tail is now flushed, process new input.
let len = length - needed;
let left = len & 0x7; // len % 8
let mut i = needed;
while i < len - left {
// SAFETY: because `len - left` is the biggest multiple of 8 under
// `len`, and because `i` starts at `needed` where `len` is `length - needed`,
// `i + 8` is guaranteed to be less than or equal to `length`.
let mi = unsafe { load_int_le!(msg, i, u64) };
self.state.v3 ^= mi;
S::c_rounds(&mut self.state);
self.state.v0 ^= mi;
i += 8;
}
// SAFETY: `i` is now `needed + len.div_euclid(8) * 8`,
// so `i + left` = `needed + len` = `length`, which is by
// definition equal to `msg.len()`.
self.tail = unsafe { u8to64_le(msg, i, left) };
self.ntail = left;
}
#[inline]
fn write_str(&mut self, s: &str) {
// This hasher works byte-wise, and `0xFF` cannot show up in a `str`,
// so just hashing the one extra byte is enough to be prefix-free.
self.write(s.as_bytes());
self.write_u8(0xFF);
}
#[inline]
fn finish(&self) -> u64 {
let mut state = self.state;
let b: u64 = ((self.length as u64 & 0xff) << 56) | self.tail;
state.v3 ^= b;
S::c_rounds(&mut state);
state.v0 ^= b;
state.v2 ^= 0xff;
S::d_rounds(&mut state);
state.v0 ^ state.v1 ^ state.v2 ^ state.v3
}
}
impl<S: Sip> Clone for Hasher<S> {
#[inline]
fn clone(&self) -> Hasher<S> {
Hasher {
k0: self.k0,
k1: self.k1,
length: self.length,
state: self.state,
tail: self.tail,
ntail: self.ntail,
_marker: self._marker,
}
}
}
impl<S: Sip> Default for Hasher<S> {
/// Creates a `Hasher<S>` with the two initial keys set to 0.
#[inline]
fn default() -> Hasher<S> {
Hasher::new_with_keys(0, 0)
}
}
#[doc(hidden)]
trait Sip {
fn c_rounds(_: &mut State);
fn d_rounds(_: &mut State);
}
#[derive(Debug, Clone, Default)]
struct Sip13Rounds;
impl Sip for Sip13Rounds {
#[inline]
fn c_rounds(state: &mut State) {
compress!(state);
}
#[inline]
fn d_rounds(state: &mut State) {
compress!(state);
compress!(state);
compress!(state);
}
}
#[derive(Debug, Clone, Default)]
struct Sip24Rounds;
impl Sip for Sip24Rounds {
#[inline]
fn c_rounds(state: &mut State) {
compress!(state);
compress!(state);
}
#[inline]
fn d_rounds(state: &mut State) {
compress!(state);
compress!(state);
compress!(state);
compress!(state);
}
}