libafl 0.15.4

Slot your own fuzzers together and extend their features using Rust
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

use alloc::vec::Vec;
use core::num::NonZero;

use libafl_bolts::rands::Rand;
use regex_syntax::hir::{Class, ClassBytesRange, ClassUnicodeRange, Hir, Literal};

#[derive(Debug)]
pub struct RegexScript {
    remaining: usize,
}

impl RegexScript {
    pub fn new<R: Rand>(rand: &mut R) -> Self {
        let len = if rand.next().is_multiple_of(256) {
            rand.next() % 0xffff
        } else {
            let len = 1 << (rand.next() % 8);
            rand.next() % len
        };
        RegexScript {
            remaining: len as usize,
        }
    }

    pub fn get_mod<R: Rand>(&mut self, rand: &mut R, val: usize) -> usize {
        if self.remaining == 0 || val == 0 {
            0
        } else {
            // # Safety
            // This is checked above to be non-null.
            rand.below(unsafe { NonZero::new(val).unwrap_unchecked() })
        }
    }

    pub fn get_range<R: Rand>(&mut self, rand: &mut R, min: usize, max: usize) -> usize {
        self.get_mod(rand, max - min) + min
    }
}

fn append_char(res: &mut Vec<u8>, chr: char) {
    let mut buf = [0; 4];
    res.extend_from_slice(chr.encode_utf8(&mut buf).as_bytes());
}

fn append_lit(res: &mut Vec<u8>, lit: &Literal) {
    res.extend_from_slice(&lit.0);
}

fn append_unicode_range<R: Rand>(
    rand: &mut R,
    res: &mut Vec<u8>,
    scr: &mut RegexScript,
    cls: ClassUnicodeRange,
) {
    let mut chr_a_buf = [0; 4];
    let mut chr_b_buf = [0; 4];
    cls.start().encode_utf8(&mut chr_a_buf);
    cls.end().encode_utf8(&mut chr_b_buf);
    let a = u32::from_le_bytes(chr_a_buf);
    let b = u32::from_le_bytes(chr_b_buf);
    let c = scr.get_range(rand, a as usize, (b + 1) as usize) as u32;
    append_char(res, core::char::from_u32(c).unwrap());
}

fn append_byte_range<R: Rand>(
    rand: &mut R,
    res: &mut Vec<u8>,
    scr: &mut RegexScript,
    cls: ClassBytesRange,
) {
    res.push(scr.get_range(rand, cls.start() as usize, (cls.end() + 1) as usize) as u8);
}

fn append_class<R: Rand>(rand: &mut R, res: &mut Vec<u8>, scr: &mut RegexScript, cls: &Class) {
    use regex_syntax::hir::Class::{Bytes, Unicode};
    match cls {
        Unicode(cls) => {
            let rngs = cls.ranges();
            let rng = rngs[scr.get_mod(rand, rngs.len())];
            append_unicode_range(rand, res, scr, rng);
        }
        Bytes(cls) => {
            let rngs = cls.ranges();
            let rng = rngs[scr.get_mod(rand, rngs.len())];
            append_byte_range(rand, res, scr, rng);
        }
    }
}

fn get_length<R: Rand>(rand: &mut R, scr: &mut RegexScript) -> usize {
    let bits = scr.get_mod(rand, 8);
    scr.get_mod(rand, 2 << bits)
}

fn get_repetition_range<R: Rand>(
    rand: &mut R,
    min: u32,
    max: Option<u32>,
    scr: &mut RegexScript,
) -> usize {
    match (min, max) {
        (a, None) => get_length(rand, scr) + (a as usize),
        (a, Some(b)) if a == b => a as usize,
        (a, Some(b)) => scr.get_range(rand, a as usize, b as usize),
    }
}

fn get_repetitions<R: Rand>(
    rand: &mut R,
    min: u32,
    max: Option<u32>,
    scr: &mut RegexScript,
) -> usize {
    match (min, max) {
        (0, Some(1)) => scr.get_mod(rand, 2),
        (0, _) => get_length(rand, scr),
        (1, _) => 1 + get_length(rand, scr),
        (min, max) => get_repetition_range(rand, min, max, scr),
    }
}

pub fn generate<R: Rand>(rand: &mut R, hir: &Hir) -> Vec<u8> {
    use regex_syntax::hir::HirKind;
    let mut scr = RegexScript::new(rand);
    let mut stack = vec![hir];
    let mut res = vec![];
    while !stack.is_empty() {
        match stack.pop().unwrap().kind() {
            HirKind::Empty => {}
            HirKind::Literal(lit) => append_lit(&mut res, lit),
            HirKind::Class(cls) => append_class(rand, &mut res, &mut scr, cls),
            HirKind::Repetition(repetition) => {
                let num = get_repetitions(rand, repetition.min, repetition.max, &mut scr);
                for _ in 0..num {
                    stack.push(&repetition.sub);
                }
            }
            HirKind::Capture(grp) => stack.push(&grp.sub),
            HirKind::Concat(hirs) => hirs.iter().rev().for_each(|h| stack.push(h)),
            HirKind::Alternation(hirs) => stack.push(&hirs[scr.get_mod(rand, hirs.len())]),
            HirKind::Look(_) => (),
        }
    }
    res
}