der/asn1/
integer.rs

Help
1//! ASN.1 `INTEGER` support.
2
3pub(super) mod int;
4pub(super) mod uint;
5
6use core::{cmp::Ordering, mem};
7
8use crate::{EncodeValue, Result, SliceWriter};
9
10/// Is the highest bit of the first byte in the slice set to `1`? (if present)
11#[inline]
12fn is_highest_bit_set(bytes: &[u8]) -> bool {
13    bytes
14        .first()
15        .map(|byte| byte & 0b10000000 != 0)
16        .unwrap_or(false)
17}
18
19/// Compare two integer values
20fn value_cmp<T>(a: T, b: T) -> Result<Ordering>
21where
22    T: Copy + EncodeValue + Sized,
23{
24    const MAX_INT_SIZE: usize = 16;
25    debug_assert!(mem::size_of::<T>() <= MAX_INT_SIZE);
26
27    let mut buf1 = [0u8; MAX_INT_SIZE];
28    let mut encoder1 = SliceWriter::new(&mut buf1);
29    a.encode_value(&mut encoder1)?;
30
31    let mut buf2 = [0u8; MAX_INT_SIZE];
32    let mut encoder2 = SliceWriter::new(&mut buf2);
33    b.encode_value(&mut encoder2)?;
34
35    Ok(encoder1.finish()?.cmp(encoder2.finish()?))
36}
37
38#[cfg(test)]
39pub(crate) mod tests {
40    use crate::{Decode, Encode};
41
42    // Vectors from Section 5.7 of:
43    // https://luca.ntop.org/Teaching/Appunti/asn1.html
44    pub(crate) const I0_BYTES: &[u8] = &[0x02, 0x01, 0x00];
45    pub(crate) const I127_BYTES: &[u8] = &[0x02, 0x01, 0x7F];
46    pub(crate) const I128_BYTES: &[u8] = &[0x02, 0x02, 0x00, 0x80];
47    pub(crate) const I256_BYTES: &[u8] = &[0x02, 0x02, 0x01, 0x00];
48    pub(crate) const INEG128_BYTES: &[u8] = &[0x02, 0x01, 0x80];
49    pub(crate) const INEG129_BYTES: &[u8] = &[0x02, 0x02, 0xFF, 0x7F];
50
51    // Additional vectors
52    pub(crate) const I255_BYTES: &[u8] = &[0x02, 0x02, 0x00, 0xFF];
53    pub(crate) const I32767_BYTES: &[u8] = &[0x02, 0x02, 0x7F, 0xFF];
54    pub(crate) const I65535_BYTES: &[u8] = &[0x02, 0x03, 0x00, 0xFF, 0xFF];
55    pub(crate) const INEG32768_BYTES: &[u8] = &[0x02, 0x02, 0x80, 0x00];
56
57    #[test]
58    fn decode_i8() {
59        assert_eq!(0, i8::from_der(I0_BYTES).unwrap());
60        assert_eq!(127, i8::from_der(I127_BYTES).unwrap());
61        assert_eq!(-128, i8::from_der(INEG128_BYTES).unwrap());
62    }
63
64    #[test]
65    fn decode_i16() {
66        assert_eq!(0, i16::from_der(I0_BYTES).unwrap());
67        assert_eq!(127, i16::from_der(I127_BYTES).unwrap());
68        assert_eq!(128, i16::from_der(I128_BYTES).unwrap());
69        assert_eq!(255, i16::from_der(I255_BYTES).unwrap());
70        assert_eq!(256, i16::from_der(I256_BYTES).unwrap());
71        assert_eq!(32767, i16::from_der(I32767_BYTES).unwrap());
72        assert_eq!(-128, i16::from_der(INEG128_BYTES).unwrap());
73        assert_eq!(-129, i16::from_der(INEG129_BYTES).unwrap());
74        assert_eq!(-32768, i16::from_der(INEG32768_BYTES).unwrap());
75    }
76
77    #[test]
78    fn decode_u8() {
79        assert_eq!(0, u8::from_der(I0_BYTES).unwrap());
80        assert_eq!(127, u8::from_der(I127_BYTES).unwrap());
81        assert_eq!(255, u8::from_der(I255_BYTES).unwrap());
82    }
83
84    #[test]
85    fn decode_u16() {
86        assert_eq!(0, u16::from_der(I0_BYTES).unwrap());
87        assert_eq!(127, u16::from_der(I127_BYTES).unwrap());
88        assert_eq!(255, u16::from_der(I255_BYTES).unwrap());
89        assert_eq!(256, u16::from_der(I256_BYTES).unwrap());
90        assert_eq!(32767, u16::from_der(I32767_BYTES).unwrap());
91        assert_eq!(65535, u16::from_der(I65535_BYTES).unwrap());
92    }
93
94    #[test]
95    fn encode_i8() {
96        let mut buffer = [0u8; 3];
97
98        assert_eq!(I0_BYTES, 0i8.encode_to_slice(&mut buffer).unwrap());
99        assert_eq!(I127_BYTES, 127i8.encode_to_slice(&mut buffer).unwrap());
100
101        assert_eq!(
102            INEG128_BYTES,
103            (-128i8).encode_to_slice(&mut buffer).unwrap()
104        );
105    }
106
107    #[test]
108    fn encode_i16() {
109        let mut buffer = [0u8; 4];
110        assert_eq!(I0_BYTES, 0i16.encode_to_slice(&mut buffer).unwrap());
111        assert_eq!(I127_BYTES, 127i16.encode_to_slice(&mut buffer).unwrap());
112        assert_eq!(I128_BYTES, 128i16.encode_to_slice(&mut buffer).unwrap());
113        assert_eq!(I255_BYTES, 255i16.encode_to_slice(&mut buffer).unwrap());
114        assert_eq!(I256_BYTES, 256i16.encode_to_slice(&mut buffer).unwrap());
115        assert_eq!(I32767_BYTES, 32767i16.encode_to_slice(&mut buffer).unwrap());
116
117        assert_eq!(
118            INEG128_BYTES,
119            (-128i16).encode_to_slice(&mut buffer).unwrap()
120        );
121
122        assert_eq!(
123            INEG129_BYTES,
124            (-129i16).encode_to_slice(&mut buffer).unwrap()
125        );
126
127        assert_eq!(
128            INEG32768_BYTES,
129            (-32768i16).encode_to_slice(&mut buffer).unwrap()
130        );
131    }
132
133    #[test]
134    fn encode_u8() {
135        let mut buffer = [0u8; 4];
136        assert_eq!(I0_BYTES, 0u8.encode_to_slice(&mut buffer).unwrap());
137        assert_eq!(I127_BYTES, 127u8.encode_to_slice(&mut buffer).unwrap());
138        assert_eq!(I255_BYTES, 255u8.encode_to_slice(&mut buffer).unwrap());
139    }
140
141    #[test]
142    fn encode_u16() {
143        let mut buffer = [0u8; 5];
144        assert_eq!(I0_BYTES, 0u16.encode_to_slice(&mut buffer).unwrap());
145        assert_eq!(I127_BYTES, 127u16.encode_to_slice(&mut buffer).unwrap());
146        assert_eq!(I128_BYTES, 128u16.encode_to_slice(&mut buffer).unwrap());
147        assert_eq!(I255_BYTES, 255u16.encode_to_slice(&mut buffer).unwrap());
148        assert_eq!(I256_BYTES, 256u16.encode_to_slice(&mut buffer).unwrap());
149        assert_eq!(I32767_BYTES, 32767u16.encode_to_slice(&mut buffer).unwrap());
150        assert_eq!(I65535_BYTES, 65535u16.encode_to_slice(&mut buffer).unwrap());
151    }
152
153    /// Integers must be encoded with a minimum number of octets
154    #[test]
155    fn reject_non_canonical() {
156        assert!(i8::from_der(&[0x02, 0x02, 0x00, 0x00]).is_err());
157        assert!(i16::from_der(&[0x02, 0x02, 0x00, 0x00]).is_err());
158        assert!(u8::from_der(&[0x02, 0x02, 0x00, 0x00]).is_err());
159        assert!(u16::from_der(&[0x02, 0x02, 0x00, 0x00]).is_err());
160    }
161}
der/asn1/integer.rs

der/asn1/
integer.rs
