mail_auth/common/
base32.rs

1/*
2 * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <hello@stalw.art>
3 *
4 * SPDX-License-Identifier: Apache-2.0 OR MIT
5 */
6
7use std::slice::Iter;
8
9use super::headers::Writer;
10
11pub(crate) static BASE32_ALPHABET: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
12pub static BASE32_INVERSE: [u8; 256] = [
13    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
14    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
15    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 26, 27, 28, 29, 30, 31, 255, 255,
16    255, 255, 255, 255, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
17    17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
18    10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255, 255,
19    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
20    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
21    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
22    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
23    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
24    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
25    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
26];
27
28pub struct Base32Writer {
29    last_byte: u8,
30    pos: usize,
31    result: String,
32}
33
34impl Base32Writer {
35    pub fn encode(bytes: &[u8]) -> String {
36        let mut w = Base32Writer::with_capacity(bytes.len());
37        w.write(bytes);
38        w.finalize()
39    }
40
41    pub fn with_capacity(capacity: usize) -> Self {
42        Base32Writer {
43            result: String::with_capacity(capacity.div_ceil(4) * 5),
44            last_byte: 0,
45            pos: 0,
46        }
47    }
48
49    pub fn push_byte(&mut self, byte: u8, is_remainder: bool) {
50        let (ch1, ch2) = match self.pos % 5 {
51            0 => ((byte & 0xF8) >> 3, u8::MAX),
52            1 => (
53                (((self.last_byte & 0x07) << 2) | ((byte & 0xC0) >> 6)),
54                ((byte & 0x3E) >> 1),
55            ),
56            2 => (
57                (((self.last_byte & 0x01) << 4) | ((byte & 0xF0) >> 4)),
58                u8::MAX,
59            ),
60            3 => (
61                (((self.last_byte & 0x0F) << 1) | (byte >> 7)),
62                ((byte & 0x7C) >> 2),
63            ),
64            4 => (
65                (((self.last_byte & 0x03) << 3) | ((byte & 0xE0) >> 5)),
66                (byte & 0x1F),
67            ),
68            _ => unreachable!(),
69        };
70
71        self.result.push(char::from(BASE32_ALPHABET[ch1 as usize]));
72        if !is_remainder {
73            if ch2 != u8::MAX {
74                self.result.push(char::from(BASE32_ALPHABET[ch2 as usize]));
75            }
76            self.last_byte = byte;
77            self.pos += 1;
78        }
79    }
80
81    pub fn finalize(mut self) -> String {
82        if self.pos % 5 != 0 {
83            self.push_byte(0, true);
84        }
85
86        self.result
87    }
88}
89
90impl Writer for Base32Writer {
91    fn write(&mut self, buf: &[u8]) {
92        for &byte in buf {
93            self.push_byte(byte, false);
94        }
95    }
96}
97
98#[derive(Debug)]
99pub struct Base32Reader<'x> {
100    bytes: Iter<'x, u8>,
101    last_byte: u8,
102    pos: usize,
103}
104
105impl<'x> Base32Reader<'x> {
106    pub fn new(bytes: &'x [u8]) -> Self {
107        Base32Reader {
108            bytes: bytes.iter(),
109            pos: 0,
110            last_byte: 0,
111        }
112    }
113
114    #[inline(always)]
115    fn map_byte(&mut self) -> Option<u8> {
116        match self.bytes.next() {
117            Some(&byte) => match BASE32_INVERSE[byte as usize] {
118                byte if byte != u8::MAX => {
119                    self.last_byte = byte;
120                    Some(byte)
121                }
122                _ => None,
123            },
124            _ => None,
125        }
126    }
127}
128
129impl Iterator for Base32Reader<'_> {
130    type Item = u8;
131    fn next(&mut self) -> Option<Self::Item> {
132        let pos = self.pos % 5;
133        let last_byte = self.last_byte;
134        let byte = self.map_byte()?;
135        self.pos += 1;
136
137        match pos {
138            0 => ((byte << 3) | (self.map_byte().unwrap_or(0) >> 2)).into(),
139            1 => ((last_byte << 6) | (byte << 1) | (self.map_byte().unwrap_or(0) >> 4)).into(),
140            2 => ((last_byte << 4) | (byte >> 1)).into(),
141            3 => ((last_byte << 7) | (byte << 2) | (self.map_byte().unwrap_or(0) >> 3)).into(),
142            4 => ((last_byte << 5) | byte).into(),
143            _ => None,
144        }
145    }
146}
147
148#[cfg(test)]
149mod tests {
150    use crate::common::{
151        base32::{Base32Reader, Base32Writer},
152        crypto::{HashContext, HashImpl, Sha1},
153        headers::Writer,
154    };
155
156    #[test]
157    fn base32_hash() {
158        for (test, expected_result) in [
159            ("one.example.net", "QSP4I4D24CRHOPDZ3O3ZIU2KSGS3X6Z6"),
160            ("two.example.net", "ZTZGRRV3F45A4U6HLDKBF3ZCOW4V2AJX"),
161        ] {
162            // Encode
163            let mut writer = Base32Writer::with_capacity(10);
164            let mut hash = Sha1::hasher();
165            hash.write(test.as_bytes());
166            let hash = hash.complete();
167            writer.write(hash.as_ref());
168            assert_eq!(writer.finalize(), expected_result);
169
170            // Decode
171            let mut original = Vec::new();
172            for byte in Base32Reader::new(expected_result.as_bytes()) {
173                original.push(byte);
174            }
175            assert_eq!(original, hash.as_ref());
176        }
177    }
178}
mail_auth/common/base32.rs

mail_auth/common/
base32.rs
