wasmparser/collections/
hash.rs

1//! Utilities for hashmap initialization based on random sources.
2
3use core::hash::{BuildHasher, Hasher};
4
5/// Wasmparser's hashing state stored per-map.
6///
7/// This is DoS-resistant when the `std` feature is activated and still somewhat
8/// resistant when it's not active but not as secure.
9#[derive(Clone, Debug)]
10pub struct RandomState(RandomStateImpl);
11
12impl Default for RandomState {
13    #[inline]
14    fn default() -> RandomState {
15        RandomState(RandomStateImpl::default())
16    }
17}
18
19impl BuildHasher for RandomState {
20    type Hasher = RandomStateHasher;
21
22    #[inline]
23    fn build_hasher(&self) -> RandomStateHasher {
24        RandomStateHasher(self.0.build_hasher())
25    }
26}
27
28/// Wasmparser's hasher type used with [`RandomState`].
29pub struct RandomStateHasher(<RandomStateImpl as BuildHasher>::Hasher);
30
31impl Hasher for RandomStateHasher {
32    #[inline]
33    fn finish(&self) -> u64 {
34        self.0.finish()
35    }
36    #[inline]
37    fn write(&mut self, bytes: &[u8]) {
38        self.0.write(bytes)
39    }
40    #[inline]
41    fn write_u8(&mut self, i: u8) {
42        self.0.write_u8(i)
43    }
44    #[inline]
45    fn write_u16(&mut self, i: u16) {
46        self.0.write_u16(i)
47    }
48    #[inline]
49    fn write_u32(&mut self, i: u32) {
50        self.0.write_u32(i)
51    }
52    #[inline]
53    fn write_u64(&mut self, i: u64) {
54        self.0.write_u64(i)
55    }
56    #[inline]
57    fn write_u128(&mut self, i: u128) {
58        self.0.write_u128(i)
59    }
60    #[inline]
61    fn write_usize(&mut self, i: usize) {
62        self.0.write_usize(i)
63    }
64    #[inline]
65    fn write_i8(&mut self, i: i8) {
66        self.0.write_i8(i)
67    }
68    #[inline]
69    fn write_i16(&mut self, i: i16) {
70        self.0.write_i16(i)
71    }
72    #[inline]
73    fn write_i32(&mut self, i: i32) {
74        self.0.write_i32(i)
75    }
76    #[inline]
77    fn write_i64(&mut self, i: i64) {
78        self.0.write_i64(i)
79    }
80    #[inline]
81    fn write_i128(&mut self, i: i128) {
82        self.0.write_i128(i)
83    }
84    #[inline]
85    fn write_isize(&mut self, i: isize) {
86        self.0.write_isize(i)
87    }
88}
89
90// When the `std` feature is active reuse the standard library's implementation
91// of hash state and hasher.
92#[cfg(feature = "std")]
93use std::collections::hash_map::RandomState as RandomStateImpl;
94
95// When the `std` feature is NOT active then rely on `ahash::RandomState`. That
96// relies on ASLR by default for randomness.
97#[derive(Clone, Debug)]
98#[cfg(not(feature = "std"))]
99struct RandomStateImpl {
100    state: ahash::RandomState,
101}
102
103#[cfg(not(feature = "std"))]
104impl Default for RandomStateImpl {
105    fn default() -> RandomStateImpl {
106        RandomStateImpl {
107            state: ahash::RandomState::new(),
108        }
109    }
110}
111
112#[cfg(not(feature = "std"))]
113impl BuildHasher for RandomStateImpl {
114    type Hasher = ahash::AHasher;
115
116    #[inline]
117    fn build_hasher(&self) -> ahash::AHasher {
118        self.state.build_hasher()
119    }
120}
wasmparser/collections/hash.rs

wasmparser/collections/
hash.rs
