--- /dev/null
+// This is a modification of base32 from https://crates.io/crates/base32(v0.4.0),
+// copied from rust-lightning.
+// The original portions of this software are Copyright (c) 2015 The base32 Developers
+// The remainder is copyright rust-lightning developers, as viewable in version control at
+// https://github.com/lightningdevkit/rust-lightning/
+
+// This file is licensed under either of
+// Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0) or
+// MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT) at your option.
+
+use alloc::vec::Vec;
+
+/// RFC4648 "extended hex" encoding table
+#[cfg(test)]
+const RFC4648_ALPHABET: &'static [u8] = b"0123456789ABCDEFGHIJKLMNOPQRSTUV";
+
+/// RFC4648 "extended hex" decoding table
+const RFC4648_INV_ALPHABET: [i8; 39] = [
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13,
+ 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+];
+
+/// Encode bytes into a base32 string.
+#[cfg(test)]
+pub fn encode(data: &[u8]) -> alloc::string::String {
+ // output_length is calculated as follows:
+ // / 5 divides the data length by the number of bits per chunk (5),
+ // * 8 multiplies the result by the number of characters per chunk (8).
+ // + 4 rounds up to the nearest character.
+ let output_length = (data.len() * 8 + 4) / 5;
+ let mut ret = encode_data(data, RFC4648_ALPHABET);
+ ret.truncate(output_length);
+
+ #[cfg(fuzzing)]
+ assert_eq!(ret.capacity(), (data.len() + 4) / 5 * 8);
+
+ alloc::string::String::from_utf8(ret).expect("Invalid UTF-8")
+}
+
+/// Decode a base32 string into a byte vector.
+pub fn decode(data: &str) -> Result<Vec<u8>, ()> {
+ let data = data.as_bytes();
+ // If the string has more characters than are required to alphabet_encode the number of bytes
+ // decodable, treat the string as invalid.
+ match data.len() % 8 { 1|3|6 => return Err(()), _ => {} }
+ Ok(decode_data(data, RFC4648_INV_ALPHABET)?)
+}
+
+/// Encode a byte slice into a base32 string.
+#[cfg(test)]
+fn encode_data(data: &[u8], alphabet: &'static [u8]) -> Vec<u8> {
+ // cap is calculated as follows:
+ // / 5 divides the data length by the number of bits per chunk (5),
+ // * 8 multiplies the result by the number of characters per chunk (8).
+ // + 4 rounds up to the nearest character.
+ let cap = (data.len() + 4) / 5 * 8;
+ let mut ret = Vec::with_capacity(cap);
+ for chunk in data.chunks(5) {
+ let mut buf = [0u8; 5];
+ for (i, &b) in chunk.iter().enumerate() {
+ buf[i] = b;
+ }
+ ret.push(alphabet[((buf[0] & 0xF8) >> 3) as usize]);
+ ret.push(alphabet[(((buf[0] & 0x07) << 2) | ((buf[1] & 0xC0) >> 6)) as usize]);
+ ret.push(alphabet[((buf[1] & 0x3E) >> 1) as usize]);
+ ret.push(alphabet[(((buf[1] & 0x01) << 4) | ((buf[2] & 0xF0) >> 4)) as usize]);
+ ret.push(alphabet[(((buf[2] & 0x0F) << 1) | (buf[3] >> 7)) as usize]);
+ ret.push(alphabet[((buf[3] & 0x7C) >> 2) as usize]);
+ ret.push(alphabet[(((buf[3] & 0x03) << 3) | ((buf[4] & 0xE0) >> 5)) as usize]);
+ ret.push(alphabet[(buf[4] & 0x1F) as usize]);
+ }
+ #[cfg(fuzzing)]
+ assert_eq!(ret.capacity(), cap);
+
+ ret
+}
+
+fn decode_data(data: &[u8], alphabet: [i8; 39]) -> Result<Vec<u8>, ()> {
+ // cap is calculated as follows:
+ // / 8 divides the data length by the number of characters per chunk (8),
+ // * 5 multiplies the result by the number of bits per chunk (5),
+ // + 7 rounds up to the nearest byte.
+ let cap = (data.len() + 7) / 8 * 5;
+ let mut ret = Vec::with_capacity(cap);
+ for chunk in data.chunks(8) {
+ let mut buf = [0u8; 8];
+ for (i, &c) in chunk.iter().enumerate() {
+ match alphabet.get(c.to_ascii_uppercase().wrapping_sub(b'0') as usize) {
+ Some(&-1) | None => return Err(()),
+ Some(&value) => buf[i] = value as u8,
+ };
+ }
+ ret.push((buf[0] << 3) | (buf[1] >> 2));
+ ret.push((buf[1] << 6) | (buf[2] << 1) | (buf[3] >> 4));
+ ret.push((buf[3] << 4) | (buf[4] >> 1));
+ ret.push((buf[4] << 7) | (buf[5] << 2) | (buf[6] >> 3));
+ ret.push((buf[6] << 5) | buf[7]);
+ }
+ let output_length = data.len() * 5 / 8;
+ for c in ret.drain(output_length..) {
+ if c != 0 {
+ // If the original string had any bits set at positions outside of the encoded data,
+ // treat the string as invalid.
+ return Err(());
+ }
+ }
+
+ // Check that our capacity calculation doesn't under-shoot in fuzzing
+ #[cfg(fuzzing)]
+ assert_eq!(ret.capacity(), cap);
+ Ok(ret)
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn test_encode_decode() {
+ let mut bytes = [0u8; 256 * 5];
+ for i in 0..=255 {
+ bytes[i as usize + 256*0] = i;
+ bytes[i as usize + 256*1] = i.wrapping_add(1);
+ bytes[i as usize + 256*2] = i.wrapping_add(2);
+ bytes[i as usize + 256*3] = i.wrapping_add(3);
+ bytes[i as usize + 256*4] = i.wrapping_add(4);
+ }
+ assert_eq!(decode(&encode(&bytes)).unwrap(), bytes);
+ }
+}
projects / dnssec-prover / commitdiff