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

mail_auth/common/
base32.rs
