Add base32 encoder/decoder

nix-rust/src/util/base32.rs

@@ -0,0 +1,140 @@
+use crate::error::Error;
+use std::collections::HashMap;
+
+pub fn encoded_len(input_len: usize) -> usize {
+    if input_len == 0 {
+        0
+    } else {
+        (input_len * 8 - 1) / 5 + 1
+    }
+}
+
+static BASE32_CHARS: &'static [u8; 32] = &b"0123456789abcdfghijklmnpqrsvwxyz";
+
+lazy_static! {
+    static ref BASE32_CHARS_REVERSE: HashMap<char, u8> = BASE32_CHARS
+        .iter()
+        .enumerate()
+        .map(|(n, c)| (*c as char, n as u8))
+        .collect();
+}
+
+pub fn encode(input: &[u8]) -> String {
+    let mut res = String::new();
+    res.reserve(encoded_len(input.len()));
+
+    let mut nr_bits_left: usize = 0;
+    let mut bits_left: u16 = 0;
+
+    for b in input {
+        bits_left |= (*b as u16) << nr_bits_left;
+        nr_bits_left += 8;
+        while nr_bits_left > 5 {
+            res.push(BASE32_CHARS[(bits_left & 0x1f) as usize] as char);
+            bits_left >>= 5;
+            nr_bits_left -= 5;
+        }
+    }
+
+    if nr_bits_left > 0 {
+        res.push(BASE32_CHARS[(bits_left & 0x1f) as usize] as char);
+    }
+
+    res.chars().rev().collect()
+}
+
+pub fn decode(input: &str) -> Result<Vec<u8>, crate::Error> {
+    let mut res = Vec::new();
+
+    let mut nr_bits_left: usize = 0;
+    let mut bits_left: u16 = 0;
+
+    for c in input.chars().rev() {
+        let x = BASE32_CHARS_REVERSE.get(&c).ok_or(Error::BadBase32)?;
+        bits_left |= (*x as u16) << nr_bits_left;
+        nr_bits_left += 5;
+        if nr_bits_left >= 8 {
+            res.push((bits_left & 0xff) as u8);
+            bits_left >>= 8;
+            nr_bits_left -= 8;
+        }
+    }
+
+    if nr_bits_left > 0 && bits_left != 0 {
+        return Err(Error::BadBase32);
+    }
+
+    Ok(res)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use hex;
+
+    #[test]
+    fn test_encode() {
+        assert_eq!(encode(&[]), "");
+
+        assert_eq!(
+            encode(&hex::decode("0839703786356bca59b0f4a32987eb2e6de43ae8").unwrap()),
+            "x0xf8v9fxf3jk8zln1cwlsrmhqvp0f88"
+        );
+
+        assert_eq!(
+            encode(
+                &hex::decode("ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad")
+                    .unwrap()
+            ),
+            "1b8m03r63zqhnjf7l5wnldhh7c134ap5vpj0850ymkq1iyzicy5s"
+        );
+
+        assert_eq!(
+            encode(
+                &hex::decode("ddaf35a193617abacc417349ae20413112e6fa4e89a97ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd454d4423643ce80e2a9ac94fa54ca49f")
+                    .unwrap()
+            ),
+            "2gs8k559z4rlahfx0y688s49m2vvszylcikrfinm30ly9rak69236nkam5ydvly1ai7xac99vxfc4ii84hawjbk876blyk1jfhkbbyx"
+        );
+    }
+
+    #[test]
+    fn test_decode() {
+        assert_eq!(hex::encode(decode("").unwrap()), "");
+
+        assert_eq!(
+            hex::encode(decode("x0xf8v9fxf3jk8zln1cwlsrmhqvp0f88").unwrap()),
+            "0839703786356bca59b0f4a32987eb2e6de43ae8"
+        );
+
+        assert_eq!(
+            hex::encode(decode("1b8m03r63zqhnjf7l5wnldhh7c134ap5vpj0850ymkq1iyzicy5s").unwrap()),
+            "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"
+        );
+
+        assert_eq!(
+            hex::encode(decode("2gs8k559z4rlahfx0y688s49m2vvszylcikrfinm30ly9rak69236nkam5ydvly1ai7xac99vxfc4ii84hawjbk876blyk1jfhkbbyx").unwrap()),
+            "ddaf35a193617abacc417349ae20413112e6fa4e89a97ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd454d4423643ce80e2a9ac94fa54ca49f"
+        );
+
+        assert_matches!(
+            decode("xoxf8v9fxf3jk8zln1cwlsrmhqvp0f88"),
+            Err(Error::BadBase32)
+        );
+        assert_matches!(
+            decode("2b8m03r63zqhnjf7l5wnldhh7c134ap5vpj0850ymkq1iyzicy5s"),
+            Err(Error::BadBase32)
+        );
+        assert_matches!(decode("2"), Err(Error::BadBase32));
+        assert_matches!(decode("2gs"), Err(Error::BadBase32));
+        assert_matches!(decode("2gs8"), Err(Error::BadBase32));
+    }
+
+    proptest! {
+
+        #[test]
+        fn roundtrip(s: Vec<u8>) {
+            assert_eq!(s, decode(&encode(&s)).unwrap());
+        }
+    }
+}

nix-rust/src/util/mod.rs

@@ -1 +1,2 @@
+pub mod base32;
 pub mod tarfile;