1// Additional x509/asn1 functions to those provided in webpki/ring.
2
3use alloc::vec::Vec;
4
5pub(crate) fn asn1_wrap(tag: u8, bytes: &[u8]) -> Vec<u8> {
6 let len = bytes.len();
7
8 if len <= 0x7f {
9 // Short form
10 let mut ret = Vec::with_capacity(2 + len);
11 ret.push(tag);
12 ret.push(len as u8);
13 ret.extend_from_slice(bytes);
14 ret
15 } else {
16 // Long form
17 let size = len.to_be_bytes();
18 let leading_zero_bytes = size
19 .iter()
20 .position(|&x| x != 0)
21 .unwrap_or(size.len());
22 assert!(leading_zero_bytes < size.len());
23 let encoded_bytes = size.len() - leading_zero_bytes;
24
25 let mut ret = Vec::with_capacity(2 + encoded_bytes + len);
26 ret.push(tag);
27
28 ret.push(0x80 + encoded_bytes as u8);
29 ret.extend_from_slice(&size[leading_zero_bytes..]);
30
31 ret.extend_from_slice(bytes);
32 ret
33 }
34}
35
36/// Prepend stuff to `bytes` to put it in a DER SEQUENCE.
37pub(crate) fn wrap_in_sequence(bytes: &[u8]) -> Vec<u8> {
38 asn1_wrap(DER_SEQUENCE_TAG, bytes)
39}
40
41const DER_SEQUENCE_TAG: u8 = 0x30;
42
43#[cfg(test)]
44mod tests {
45 use super::*;
46
47 #[test]
48 fn test_empty() {
49 assert_eq!(vec![0x30, 0x00], wrap_in_sequence(&[]));
50 }
51
52 #[test]
53 fn test_small() {
54 assert_eq!(
55 vec![0x30, 0x04, 0x00, 0x11, 0x22, 0x33],
56 wrap_in_sequence(&[0x00, 0x11, 0x22, 0x33])
57 );
58 }
59
60 #[test]
61 fn test_medium() {
62 let mut val = Vec::new();
63 val.resize(255, 0x12);
64 assert_eq!(
65 vec![0x30, 0x81, 0xff, 0x12, 0x12, 0x12],
66 wrap_in_sequence(&val)[..6]
67 );
68 }
69
70 #[test]
71 fn test_large() {
72 let mut val = Vec::new();
73 val.resize(4660, 0x12);
74 wrap_in_sequence(&val);
75 assert_eq!(
76 vec![0x30, 0x82, 0x12, 0x34, 0x12, 0x12],
77 wrap_in_sequence(&val)[..6]
78 );
79 }
80
81 #[test]
82 fn test_huge() {
83 let mut val = Vec::new();
84 val.resize(0xffff, 0x12);
85 let result = wrap_in_sequence(&val);
86 assert_eq!(vec![0x30, 0x82, 0xff, 0xff, 0x12, 0x12], result[..6]);
87 assert_eq!(result.len(), 0xffff + 4);
88 }
89
90 #[test]
91 fn test_gigantic() {
92 let mut val = Vec::new();
93 val.resize(0x100000, 0x12);
94 let result = wrap_in_sequence(&val);
95 assert_eq!(vec![0x30, 0x83, 0x10, 0x00, 0x00, 0x12, 0x12], result[..7]);
96 assert_eq!(result.len(), 0x100000 + 5);
97 }
98
99 #[test]
100 fn test_ludicrous() {
101 let mut val = Vec::new();
102 val.resize(0x1000000, 0x12);
103 let result = wrap_in_sequence(&val);
104 assert_eq!(
105 vec![0x30, 0x84, 0x01, 0x00, 0x00, 0x00, 0x12, 0x12],
106 result[..8]
107 );
108 assert_eq!(result.len(), 0x1000000 + 6);
109 }
110}
111