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+// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! An implementation of SipHash with a 128-bit output.
+
+use core::cmp;
+use core::hash;
+use core::marker::PhantomData;
+use core::mem;
+use core::ptr;
+use core::u64;
+
+/// A 128-bit (2x64) hash output
+#[derive(Debug, Clone, Copy, Default)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub struct Hash128 {
+ pub h1: u64,
+ pub h2: u64,
+}
+
+impl From<u128> for Hash128 {
+ fn from(v: u128) -> Self {
+ Hash128 {
+ h1: v as u64,
+ h2: (v >> 64) as u64,
+ }
+ }
+}
+
+impl From<Hash128> for u128 {
+ fn from(h: Hash128) -> u128 {
+ (h.h1 as u128) | ((h.h2 as u128) << 64)
+ }
+}
+
+/// An implementation of SipHash128 1-3.
+#[derive(Debug, Clone, Copy, Default)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub struct SipHasher13 {
+ hasher: Hasher<Sip13Rounds>,
+}
+
+/// An implementation of SipHash128 2-4.
+#[derive(Debug, Clone, Copy, Default)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub struct SipHasher24 {
+ hasher: Hasher<Sip24Rounds>,
+}
+
+/// An implementation of SipHash128 2-4.
+///
+/// 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 hashtables from a strong RNG, such as
+/// [`rand::os::OsRng`](https://doc.rust-lang.org/rand/rand/os/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_.
+#[derive(Debug, Clone, Copy, Default)]
+pub struct SipHasher(SipHasher24);
+
+#[derive(Debug, Copy)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+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)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+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);
+ $v1 = $v1.rotate_left(13);
+ $v1 ^= $v0;
+ $v0 = $v0.rotate_left(32);
+ $v2 = $v2.wrapping_add($v3);
+ $v3 = $v3.rotate_left(16);
+ $v3 ^= $v2;
+ $v0 = $v0.wrapping_add($v3);
+ $v3 = $v3.rotate_left(21);
+ $v3 ^= $v0;
+ $v2 = $v2.wrapping_add($v1);
+ $v1 = $v1.rotate_left(17);
+ $v1 ^= $v2;
+ $v2 = $v2.rotate_left(32);
+ }};
+}
+
+/// Loads an integer of the desired type from a byte stream, in LE order. Uses
+/// `copy_nonoverlapping` to let the compiler generate the most efficient way
+/// to load it from a possibly unaligned address.
+///
+/// Unsafe because: unchecked indexing at `i..i+size_of(int_ty)`
+macro_rules! load_int_le {
+ ($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.
+///
+/// Unsafe because: unchecked indexing at start..start+len
+#[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 {
+ out = load_int_le!(buf, start + i, u32) as u64;
+ i += 4;
+ }
+ if i + 1 < len {
+ out |= (load_int_le!(buf, start + i, u16) as u64) << (i * 8);
+ i += 2
+ }
+ if i < len {
+ out |= (*buf.get_unchecked(start + i) as u64) << (i * 8);
+ i += 1;
+ }
+ debug_assert_eq!(i, len);
+ out
+}
+
+pub trait Hasher128 {
+ /// Return a 128-bit hash
+ fn finish128(&self) -> Hash128;
+}
+
+impl SipHasher {
+ /// Creates a new `SipHasher` with the two initial keys set to 0.
+ #[inline]
+ pub fn new() -> SipHasher {
+ SipHasher::new_with_keys(0, 0)
+ }
+
+ /// Creates a `SipHasher` that is keyed off the provided keys.
+ #[inline]
+ pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher {
+ SipHasher(SipHasher24::new_with_keys(key0, key1))
+ }
+
+ /// Creates a `SipHasher` from a 16 byte key.
+ pub fn new_with_key(key: &[u8; 16]) -> SipHasher {
+ let mut b0 = [0u8; 8];
+ let mut b1 = [0u8; 8];
+ b0.copy_from_slice(&key[0..8]);
+ b1.copy_from_slice(&key[8..16]);
+ let key0 = u64::from_le_bytes(b0);
+ let key1 = u64::from_le_bytes(b1);
+ Self::new_with_keys(key0, key1)
+ }
+
+ /// Get the keys used by this hasher
+ pub fn keys(&self) -> (u64, u64) {
+ (self.0.hasher.k0, self.0.hasher.k1)
+ }
+
+ /// Get the key used by this hasher as a 16 byte vector
+ pub fn key(&self) -> [u8; 16] {
+ let mut bytes = [0u8; 16];
+ bytes[0..8].copy_from_slice(&self.0.hasher.k0.to_le_bytes());
+ bytes[8..16].copy_from_slice(&self.0.hasher.k1.to_le_bytes());
+ bytes
+ }
+}
+
+impl Hasher128 for SipHasher {
+ /// Return a 128-bit hash
+ #[inline]
+ fn finish128(&self) -> Hash128 {
+ self.0.finish128()
+ }
+}
+
+impl SipHasher13 {
+ /// Creates a new `SipHasher13` with the two initial keys set to 0.
+ #[inline]
+ pub fn new() -> SipHasher13 {
+ SipHasher13::new_with_keys(0, 0)
+ }
+
+ /// Creates a `SipHasher13` that is keyed off the provided keys.
+ #[inline]
+ pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher13 {
+ SipHasher13 {
+ hasher: Hasher::new_with_keys(key0, key1),
+ }
+ }
+
+ /// Creates a `SipHasher13` from a 16 byte key.
+ pub fn new_with_key(key: &[u8; 16]) -> SipHasher13 {
+ let mut b0 = [0u8; 8];
+ let mut b1 = [0u8; 8];
+ b0.copy_from_slice(&key[0..8]);
+ b1.copy_from_slice(&key[8..16]);
+ let key0 = u64::from_le_bytes(b0);
+ let key1 = u64::from_le_bytes(b1);
+ Self::new_with_keys(key0, key1)
+ }
+
+ /// Get the keys used by this hasher
+ pub fn keys(&self) -> (u64, u64) {
+ (self.hasher.k0, self.hasher.k1)
+ }
+
+ /// Get the key used by this hasher as a 16 byte vector
+ pub fn key(&self) -> [u8; 16] {
+ let mut bytes = [0u8; 16];
+ bytes[0..8].copy_from_slice(&self.hasher.k0.to_le_bytes());
+ bytes[8..16].copy_from_slice(&self.hasher.k1.to_le_bytes());
+ bytes
+ }
+}
+
+impl Hasher128 for SipHasher13 {
+ /// Return a 128-bit hash
+ #[inline]
+ fn finish128(&self) -> Hash128 {
+ self.hasher.finish128()
+ }
+}
+
+impl SipHasher24 {
+ /// Creates a new `SipHasher24` with the two initial keys set to 0.
+ #[inline]
+ pub fn new() -> SipHasher24 {
+ SipHasher24::new_with_keys(0, 0)
+ }
+
+ /// Creates a `SipHasher24` that is keyed off the provided keys.
+ #[inline]
+ pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher24 {
+ SipHasher24 {
+ hasher: Hasher::new_with_keys(key0, key1),
+ }
+ }
+
+ /// Creates a `SipHasher24` from a 16 byte key.
+ pub fn new_with_key(key: &[u8; 16]) -> SipHasher24 {
+ let mut b0 = [0u8; 8];
+ let mut b1 = [0u8; 8];
+ b0.copy_from_slice(&key[0..8]);
+ b1.copy_from_slice(&key[8..16]);
+ let key0 = u64::from_le_bytes(b0);
+ let key1 = u64::from_le_bytes(b1);
+ Self::new_with_keys(key0, key1)
+ }
+
+ /// Get the keys used by this hasher
+ pub fn keys(&self) -> (u64, u64) {
+ (self.hasher.k0, self.hasher.k1)
+ }
+
+ /// Get the key used by this hasher as a 16 byte vector
+ pub fn key(&self) -> [u8; 16] {
+ let mut bytes = [0u8; 16];
+ bytes[0..8].copy_from_slice(&self.hasher.k0.to_le_bytes());
+ bytes[8..16].copy_from_slice(&self.hasher.k1.to_le_bytes());
+ bytes
+ }
+}
+
+impl Hasher128 for SipHasher24 {
+ /// Return a 128-bit hash
+ #[inline]
+ fn finish128(&self) -> Hash128 {
+ self.hasher.finish128()
+ }
+}
+
+impl<S: Sip> Hasher<S> {
+ #[inline]
+ 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: 0xee,
+ v2: 0,
+ v3: 0,
+ },
+ tail: 0,
+ ntail: 0,
+ _marker: PhantomData,
+ };
+ state.reset();
+ state
+ }
+
+ #[inline]
+ fn reset(&mut self) {
+ self.length = 0;
+ self.state.v0 = self.k0 ^ 0x736f6d6570736575;
+ self.state.v1 = self.k1 ^ 0x646f72616e646f83;
+ self.state.v2 = self.k0 ^ 0x6c7967656e657261;
+ self.state.v3 = self.k1 ^ 0x7465646279746573;
+ self.ntail = 0;
+ }
+
+ // A specialized write function for values with size <= 8.
+ //
+ // The hashing of multi-byte integers depends on endianness. E.g.:
+ // - little-endian: `write_u32(0xDDCCBBAA)` == `write([0xAA, 0xBB, 0xCC, 0xDD])`
+ // - big-endian: `write_u32(0xDDCCBBAA)` == `write([0xDD, 0xCC, 0xBB, 0xAA])`
+ //
+ // This function does the right thing for little-endian hardware. On
+ // big-endian hardware `x` must be byte-swapped first to give the right
+ // behaviour. After any byte-swapping, the input must be zero-extended to
+ // 64-bits. The caller is responsible for the byte-swapping and
+ // zero-extension.
+ #[inline]
+ fn short_write<T>(&mut self, _x: T, x: u64) {
+ let size = mem::size_of::<T>();
+ self.length += size;
+
+ // The original number must be zero-extended, not sign-extended.
+ debug_assert!(if size < 8 { x >> (8 * size) == 0 } else { true });
+
+ // The number of bytes needed to fill `self.tail`.
+ let needed = 8 - self.ntail;
+
+ self.tail |= x << (8 * self.ntail);
+ if size < needed {
+ self.ntail += size;
+ return;
+ }
+
+ // `self.tail` is full, process it.
+ self.state.v3 ^= self.tail;
+ S::c_rounds(&mut self.state);
+ self.state.v0 ^= self.tail;
+
+ self.ntail = size - needed;
+ self.tail = if needed < 8 { x >> (8 * needed) } else { 0 };
+ }
+}
+
+impl<S: Sip> Hasher<S> {
+ #[inline]
+ pub fn finish128(&self) -> Hash128 {
+ 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 ^= 0xee;
+ S::d_rounds(&mut state);
+ let h1 = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
+
+ state.v1 ^= 0xdd;
+ S::d_rounds(&mut state);
+ let h2 = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
+
+ Hash128 { h1, h2 }
+ }
+}
+
+impl hash::Hasher for SipHasher {
+ #[inline]
+ fn write(&mut self, msg: &[u8]) {
+ self.0.write(msg)
+ }
+
+ #[inline]
+ fn finish(&self) -> u64 {
+ self.0.finish()
+ }
+
+ #[inline]
+ fn write_usize(&mut self, i: usize) {
+ self.0.write_usize(i);
+ }
+
+ #[inline]
+ fn write_u8(&mut self, i: u8) {
+ self.0.write_u8(i);
+ }
+
+ #[inline]
+ fn write_u16(&mut self, i: u16) {
+ self.0.write_u16(i);
+ }
+
+ #[inline]
+ fn write_u32(&mut self, i: u32) {
+ self.0.write_u32(i);
+ }
+
+ #[inline]
+ fn write_u64(&mut self, i: u64) {
+ self.0.write_u64(i);
+ }
+}
+
+impl hash::Hasher for SipHasher13 {
+ #[inline]
+ fn write(&mut self, msg: &[u8]) {
+ self.hasher.write(msg)
+ }
+
+ #[inline]
+ fn finish(&self) -> u64 {
+ self.hasher.finish()
+ }
+
+ #[inline]
+ fn write_usize(&mut self, i: usize) {
+ self.hasher.write_usize(i);
+ }
+
+ #[inline]
+ fn write_u8(&mut self, i: u8) {
+ self.hasher.write_u8(i);
+ }
+
+ #[inline]
+ fn write_u16(&mut self, i: u16) {
+ self.hasher.write_u16(i);
+ }
+
+ #[inline]
+ fn write_u32(&mut self, i: u32) {
+ self.hasher.write_u32(i);
+ }
+
+ #[inline]
+ fn write_u64(&mut self, i: u64) {
+ self.hasher.write_u64(i);
+ }
+}
+
+impl hash::Hasher for SipHasher24 {
+ #[inline]
+ fn write(&mut self, msg: &[u8]) {
+ self.hasher.write(msg)
+ }
+
+ #[inline]
+ fn finish(&self) -> u64 {
+ self.hasher.finish()
+ }
+
+ #[inline]
+ fn write_usize(&mut self, i: usize) {
+ self.hasher.write_usize(i);
+ }
+
+ #[inline]
+ fn write_u8(&mut self, i: u8) {
+ self.hasher.write_u8(i);
+ }
+
+ #[inline]
+ fn write_u16(&mut self, i: u16) {
+ self.hasher.write_u16(i);
+ }
+
+ #[inline]
+ fn write_u32(&mut self, i: u32) {
+ self.hasher.write_u32(i);
+ }
+
+ #[inline]
+ fn write_u64(&mut self, i: u64) {
+ self.hasher.write_u64(i);
+ }
+}
+
+impl<S: Sip> hash::Hasher for Hasher<S> {
+ #[inline]
+ fn write_usize(&mut self, i: usize) {
+ self.short_write(i, i.to_le() as u64);
+ }
+
+ #[inline]
+ fn write_u8(&mut self, i: u8) {
+ self.short_write(i, i as u64);
+ }
+
+ #[inline]
+ fn write_u32(&mut self, i: u32) {
+ self.short_write(i, i.to_le() as u64);
+ }
+
+ #[inline]
+ fn write_u64(&mut self, i: u64) {
+ self.short_write(i, i.to_le() as u64);
+ }
+
+ #[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;
+ 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;
+
+ let mut i = needed;
+ while i < len - left {
+ 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;
+ }
+
+ self.tail = unsafe { u8to64_le(msg, i, left) };
+ self.ntail = left;
+ }
+
+ #[inline]
+ fn finish(&self) -> u64 {
+ self.finish128().h2
+ }
+}
+
+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, Copy, 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, Copy, 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);
+ }
+}
+
+impl Hash128 {
+ /// Convert into a 16-bytes vector
+ pub fn as_bytes(&self) -> [u8; 16] {
+ let mut bytes = [0u8; 16];
+ let h1 = self.h1.to_le();
+ let h2 = self.h2.to_le();
+ unsafe {
+ ptr::copy_nonoverlapping(&h1 as *const _ as *const u8, bytes.as_mut_ptr(), 8);
+ ptr::copy_nonoverlapping(&h2 as *const _ as *const u8, bytes.as_mut_ptr().add(8), 8);
+ }
+ bytes
+ }
+
+ /// Convert into a `u128`
+ #[inline]
+ pub fn as_u128(&self) -> u128 {
+ let h1 = self.h1.to_le();
+ let h2 = self.h2.to_le();
+ h1 as u128 | ((h2 as u128) << 64)
+ }
+
+ /// Convert into `(u64, u64)`
+ #[inline]
+ pub fn as_u64(&self) -> (u64, u64) {
+ let h1 = self.h1.to_le();
+ let h2 = self.h2.to_le();
+ (h1, h2)
+ }
+}
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