feat(tvix/nix-compat): introduce parsing for Nix Hash strings

We ironically didn't add support parsing for the "native" format that
Nix uses under the hood.

This extends the from_str method to peek at the prefix of the string to
determine whether to try decoding as SRI, Nix string, or whether it
should be a bare digest.

Change-Id: I33efd24968b16f86eff18305b4ca8f112c7131d7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8216
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
This commit is contained in:
Florian Klink 2023-03-04 01:39:18 +01:00 committed by tazjin
parent 4cc4b2a814
commit 67c9e2c770

View file

@ -46,16 +46,6 @@ impl TryFrom<&str> for HashAlgo {
} }
} }
// return the number of bytes in the digest of the given hash algo.
fn hash_algo_length(hash_algo: &HashAlgo) -> usize {
match hash_algo {
HashAlgo::Sha1 => 20,
HashAlgo::Sha256 => 32,
HashAlgo::Sha512 => 64,
HashAlgo::Md5 => 16,
}
}
/// Errors related to NixHash construction. /// Errors related to NixHash construction.
#[derive(Debug, Error)] #[derive(Debug, Error)]
pub enum Error { pub enum Error {
@ -71,61 +61,29 @@ pub enum Error {
InvalidBase32Encoding(nixbase32::Nixbase32DecodeError), InvalidBase32Encoding(nixbase32::Nixbase32DecodeError),
#[error("invalid base64 encoding: {0}")] #[error("invalid base64 encoding: {0}")]
InvalidBase64Encoding(data_encoding::DecodeError), InvalidBase64Encoding(data_encoding::DecodeError),
#[error("conflicting hash algo: {0} (hash_algo) vs {1} (SRI)")] #[error("conflicting hash algo: {0} (hash_algo) vs {1} (inline)")]
ConflictingHashAlgos(String, String), ConflictingHashAlgos(String, String),
} #[error("missing inline hash algo, but no externally-specified algo: {0}")]
MissingInlineHashAlgo(String),
/// decode a string depending on the hash algo specified externally.
fn decode_digest(s: &str, algo: HashAlgo) -> Result<NixHash, Error> {
// for the chosen hash algo, calculate the expected digest length (as bytes)
let expected_digest_len = hash_algo_length(&algo);
Ok(NixHash {
digest: match s.len() {
n if n == data_encoding::HEXLOWER.encode_len(expected_digest_len) => {
data_encoding::HEXLOWER
.decode(s.as_ref())
.map_err(Error::InvalidBase16Encoding)
}
n if n == nixbase32::encode_len(expected_digest_len) => {
nixbase32::decode(s.as_ref()).map_err(Error::InvalidBase32Encoding)
}
n if n == BASE64.encode_len(expected_digest_len) => BASE64
.decode(s.as_ref())
.map_err(Error::InvalidBase64Encoding),
_ => {
// another length than what we expected from the passed hash algo
// try to parse as SRI
let nix_hash = from_sri_str(s)?;
// ensure the algo matches what was specified
if algo != nix_hash.algo {
return Err(Error::ConflictingHashAlgos(
algo.to_string(),
nix_hash.algo.to_string(),
));
}
// return
return Ok(nix_hash);
}
}?,
algo,
})
} }
/// parses a string to a nix hash. /// parses a string to a nix hash.
/// ///
/// strings can be encoded as: /// Hashes can be:
/// - Nix hash strings
/// - SRI hashes
/// - bare digests
///
/// Encoding for Nix hash strings or bare digests can be:
/// - base16 (lowerhex), /// - base16 (lowerhex),
/// - nixbase32, /// - nixbase32,
/// - base64 (StdEncoding) /// - base64 (StdEncoding)
/// - sri string /// - sri string
/// ///
/// The encoding is derived from the length of the string and the hash type. /// The encoding is derived from the length of the string and the hash type.
/// The hash type may be omitted if the hash is expressed in SRI. /// The hash is communicated out-of-band, but might also be in-band (in the
/// Even though SRI allows specifying multiple algorithms, Nix does only /// case of a nix hash string or SRI), in which it needs to be consistent with the
/// support a single one. /// one communicated out-of-band.
pub fn from_str(s: &str, algo_str: Option<&str>) -> Result<NixHash, Error> { pub fn from_str(s: &str, algo_str: Option<&str>) -> Result<NixHash, Error> {
// validate algo_str, construct hash_algo // validate algo_str, construct hash_algo
let algo: Option<HashAlgo> = match &algo_str { let algo: Option<HashAlgo> = match &algo_str {
@ -137,18 +95,68 @@ pub fn from_str(s: &str, algo_str: Option<&str>) -> Result<NixHash, Error> {
None => None, None => None,
}; };
// in case the hash algo is set, decode the digest and return // peek at the beginning of the string. Let's detect the SRI path first.
if let Some(algo) = algo { if s.starts_with("sha1-")
Ok(decode_digest(s, algo))? || s.starts_with("sha256-")
} else { || s.starts_with("sha512-")
// try to decode as SRI || s.starts_with("md5-")
let nix_hash = from_sri_str(s)?; {
// and return let parsed_nixhash = from_sri_str(s)?;
Ok(nix_hash) // ensure the algo matches with what has been passed externally, if so.
if let Some(algo) = algo {
if algo != parsed_nixhash.algo {
return Err(Error::ConflictingHashAlgos(
algo.to_string(),
parsed_nixhash.algo.to_string(),
));
}
}
return Ok(parsed_nixhash);
}
// Now, peek at the beginning again to see if it's a Nix Hash
if s.starts_with("sha1:")
|| s.starts_with("sha256:")
|| s.starts_with("sha512:")
|| s.starts_with("md5:")
{
let parsed_nixhash = from_nix_str(s)?;
// ensure the algo matches with what has been passed externally, if so.
if let Some(algo) = algo {
if algo != parsed_nixhash.algo {
return Err(Error::ConflictingHashAlgos(
algo.to_string(),
parsed_nixhash.algo.to_string(),
));
}
}
return Ok(parsed_nixhash);
}
// In all other cases, we assume a bare digest, so there MUST be an externally-passed algo.
match algo {
// Fail if there isn't.
None => Err(Error::MissingInlineHashAlgo(s.to_string())),
Some(algo) => decode_digest(s, algo),
} }
} }
/// Like [from_str], but only for SRI string. /// Parses a Nix hash string ($algo:$digest) to a NixHash.
pub fn from_nix_str(s: &str) -> Result<NixHash, Error> {
if let Some(rest) = s.strip_prefix("sha1:") {
decode_digest(rest, HashAlgo::Sha1)
} else if let Some(rest) = s.strip_prefix("sha256:") {
decode_digest(rest, HashAlgo::Sha256)
} else if let Some(rest) = s.strip_prefix("sha512:") {
decode_digest(rest, HashAlgo::Sha512)
} else if let Some(rest) = s.strip_prefix("md5:") {
decode_digest(rest, HashAlgo::Md5)
} else {
Err(Error::InvalidAlgo(s.to_string()))
}
}
/// Parses a Nix SRI string to a NixHash.
/// Contrary to the SRI spec, Nix doesn't support SRI strings with multiple hashes, /// Contrary to the SRI spec, Nix doesn't support SRI strings with multiple hashes,
/// only supports sha256 and sha512 from the spec, and supports sha1 and md5 /// only supports sha256 and sha512 from the spec, and supports sha1 and md5
/// additionally. /// additionally.
@ -195,132 +203,191 @@ pub fn from_sri_str(s: &str) -> Result<NixHash, Error> {
} }
} }
/// decode a plain digest depending on the hash algo specified externally.
fn decode_digest(s: &str, algo: HashAlgo) -> Result<NixHash, Error> {
// for the chosen hash algo, calculate the expected (decoded) digest length
// (as bytes)
let expected_digest_len = hash_algo_length(&algo);
Ok(NixHash {
digest: match s.len() {
n if n == data_encoding::HEXLOWER.encode_len(expected_digest_len) => {
data_encoding::HEXLOWER
.decode(s.as_ref())
.map_err(Error::InvalidBase16Encoding)
}
n if n == nixbase32::encode_len(expected_digest_len) => {
nixbase32::decode(s.as_ref()).map_err(Error::InvalidBase32Encoding)
}
n if n == BASE64.encode_len(expected_digest_len) => BASE64
.decode(s.as_ref())
.map_err(Error::InvalidBase64Encoding),
_ => return Err(Error::InvalidEncodedDigestLength(s.len(), algo)),
}?,
algo,
})
}
// return the number of bytes in the digest of the given hash algo.
fn hash_algo_length(hash_algo: &HashAlgo) -> usize {
match hash_algo {
HashAlgo::Sha1 => 20,
HashAlgo::Sha256 => 32,
HashAlgo::Sha512 => 64,
HashAlgo::Md5 => 16,
}
}
#[cfg(test)] #[cfg(test)]
mod tests { mod tests {
use crate::nixhash::{self, HashAlgo}; use crate::{
nixbase32,
nixhash::{self, HashAlgo, NixHash},
};
use test_case::test_case;
const DIGEST_SHA1: &[u8] = &[
0x60, 0x16, 0x77, 0x79, 0x97, 0xc3, 0x0a, 0xb0, 0x24, 0x13, 0xcf, 0x50, 0x95, 0x62, 0x2c,
0xd7, 0x92, 0x42, 0x83, 0xac,
];
const SHA256_SRI: &str = "sha256-pc6cFV7Qk5dhRkbJcX/HzZSxAj17drYY1Ank/v1unTk="; const DIGEST_SHA256: &[u8] = &[
const SHA256_BASE16: &str = "a5ce9c155ed09397614646c9717fc7cd94b1023d7b76b618d409e4fefd6e9d39"; 0xa5, 0xce, 0x9c, 0x15, 0x5e, 0xd0, 0x93, 0x97, 0x61, 0x46, 0x46, 0xc9, 0x71, 0x7f, 0xc7,
const SHA256_NIXBASE32: &str = "0fcxdvyzxr09shcbcxkv7l1b356dqxzp3ja68rhrg4yhbqarrkm5"; 0xcd, 0x94, 0xb1, 0x02, 0x3d, 0x7b, 0x76, 0xb6, 0x18, 0xd4, 0x09, 0xe4, 0xfe, 0xfd, 0x6e,
const SHA256_BASE64: &str = "pc6cFV7Qk5dhRkbJcX/HzZSxAj17drYY1Ank/v1unTk="; 0x9d, 0x39,
];
const SHA1_SRI: &str = "sha1-YBZ3eZfDCrAkE89QlWIs15JCg6w="; const DIGEST_SHA512: &[u8] = &[
const SHA1_BASE16: &str = "6016777997c30ab02413cf5095622cd7924283ac"; 0xab, 0x40, 0xd0, 0xbe, 0x35, 0x41, 0xf0, 0x77, 0x4b, 0xba, 0x78, 0x15, 0xd1, 0x3d, 0x10,
const SHA1_NIXBASE32: &str = "mj1l54np5ii9al6g2cjb02n3jxwpf5k0"; 0xb0, 0x32, 0x52, 0xe9, 0x6e, 0x95, 0xf7, 0xdb, 0xb4, 0xee, 0x99, 0xa3, 0xb4, 0x31, 0xc2,
const SHA1_BASE64: &str = "YBZ3eZfDCrAkE89QlWIs15JCg6w="; 0x16, 0x62, 0xfd, 0x69, 0x71, 0xa0, 0x20, 0x16, 0x0e, 0x39, 0x84, 0x8a, 0xa5, 0xf3, 0x05,
0xb9, 0xbe, 0x0f, 0x78, 0x72, 0x7b, 0x2b, 0x07, 0x89, 0xe3, 0x9f, 0x12, 0x4d, 0x21, 0xe9,
0x2b, 0x8f, 0x39, 0xef,
];
const DIGEST_MD5: &[u8] = &[
0xc4, 0x87, 0x4a, 0x88, 0x97, 0x44, 0x0b, 0x39, 0x3d, 0x86, 0x2d, 0x8f, 0xd4, 0x59, 0x07,
0x3f,
];
const MD5_SRI: &str = "md5-xIdKiJdECzk9hi2P1FkHPw=="; fn to_base16(digest: &[u8]) -> String {
const MD5_BASE16: &str = "c4874a8897440b393d862d8fd459073f"; data_encoding::HEXLOWER.encode(digest)
const MD5_NIXBASE32: &str = "1z0xcx93rdhqykj2s4jy44m1y4";
const MD5_BASE64: &str = "xIdKiJdECzk9hi2P1FkHPw==";
const SHA512_SRI: &str = "sha512-q0DQvjVB8HdLungV0T0QsDJS6W6V99u07pmjtDHCFmL9aXGgIBYOOYSKpfMFub4PeHJ7KweJ458STSHpK4857w==";
const SHA512_BASE16: &str = "ab40d0be3541f0774bba7815d13d10b03252e96e95f7dbb4ee99a3b431c21662fd6971a020160e39848aa5f305b9be0f78727b2b0789e39f124d21e92b8f39ef";
const SHA512_NIXBASE32: &str = "3pkk3rbx4hls4lzwf4hfavvf9w0zgmr0prsb2l47471c850f5lzsqhnq8qv98wrxssdpxwmdvlm4cmh20yx25bqp95pgw216nzd0h5b";
const SHA512_BASE64: &str =
"q0DQvjVB8HdLungV0T0QsDJS6W6V99u07pmjtDHCFmL9aXGgIBYOOYSKpfMFub4PeHJ7KweJ458STSHpK4857w==";
/// Test parsing a hash without a hash algo specified works if the hash is
/// in SRI format, and works for all formats if the hash algo is specified.
#[test]
fn from_str() {
let nix_hash_1 = nixhash::from_str(SHA256_SRI, None).expect("must succeed");
assert_eq!(HashAlgo::Sha256, nix_hash_1.algo);
assert_eq!(
vec![
0xa5, 0xce, 0x9c, 0x15, 0x5e, 0xd0, 0x93, 0x97, 0x61, 0x46, 0x46, 0xc9, 0x71, 0x7f,
0xc7, 0xcd, 0x94, 0xb1, 0x02, 0x3d, 0x7b, 0x76, 0xb6, 0x18, 0xd4, 0x09, 0xe4, 0xfe,
0xfd, 0x6e, 0x9d, 0x39
],
nix_hash_1.digest
);
// pass the same string, while also specifying the algo
let nix_hash_2 = nixhash::from_str(SHA256_SRI, Some("sha256")).expect("must succeed");
// this should be equal to nix_hash_1
assert_eq!(nix_hash_1, nix_hash_2);
// parse as base16, while specifying the algo
let nix_hash_base16 =
nixhash::from_str(SHA256_BASE16, Some("sha256")).expect("must succeed");
// this should be equal to nix_hash_1
assert_eq!(nix_hash_1, nix_hash_base16);
// parse as nixbase32, while specifying the algo
let nix_hash_nixbase32 =
nixhash::from_str(SHA256_NIXBASE32, Some("sha256")).expect("must succeed");
// this should be equal to nix_hash_1
assert_eq!(nix_hash_1, nix_hash_nixbase32);
// parse as base64, while specifying the algo
let nix_hash_base64 =
nixhash::from_str(SHA256_BASE64, Some("sha256")).expect("must succeed");
// this should be equal to nix_hash_1
assert_eq!(nix_hash_1, nix_hash_base64);
} }
#[test] fn to_nixbase32(digest: &[u8]) -> String {
fn from_str_sha1() { nixbase32::encode(digest)
let nix_hash_sha1 = nixhash::from_str(SHA1_SRI, None).expect("must succeed");
assert_eq!(HashAlgo::Sha1, nix_hash_sha1.algo);
assert_eq!(
nix_hash_sha1,
nixhash::from_str(SHA1_BASE16, Some("sha1")).expect("must succeed")
);
assert_eq!(
nix_hash_sha1,
nixhash::from_str(SHA1_NIXBASE32, Some("sha1")).expect("must succeed")
);
assert_eq!(
nix_hash_sha1,
nixhash::from_str(SHA1_BASE64, Some("sha1")).expect("must succeed")
);
} }
#[test] fn to_base64(digest: &[u8]) -> String {
fn from_str_md5() { data_encoding::BASE64.encode(digest)
let nix_hash_md5 = nixhash::from_str(MD5_SRI, None).expect("must succeed");
assert_eq!(HashAlgo::Md5, nix_hash_md5.algo);
assert_eq!(
nix_hash_md5,
nixhash::from_str(MD5_BASE16, Some("md5")).expect("must succeed")
);
assert_eq!(
nix_hash_md5,
nixhash::from_str(MD5_NIXBASE32, Some("md5")).expect("must succeed")
);
assert_eq!(
nix_hash_md5,
nixhash::from_str(MD5_BASE64, Some("md5")).expect("must succeed")
);
}
#[test]
fn from_str_sha512() {
let nix_hash_sha512 = nixhash::from_str(SHA512_SRI, None).expect("must succeed");
assert_eq!(HashAlgo::Sha512, nix_hash_sha512.algo);
assert_eq!(
nix_hash_sha512,
nixhash::from_str(SHA512_BASE16, Some("sha512")).expect("must succeed")
);
assert_eq!(
nix_hash_sha512,
nixhash::from_str(SHA512_NIXBASE32, Some("sha512")).expect("must succeed")
);
assert_eq!(
nix_hash_sha512,
nixhash::from_str(SHA512_BASE64, Some("sha512")).expect("must succeed")
);
} }
/// Test a algo needs to be specified if the hash itself is not SRI. fn to_base64_nopad(digest: &[u8]) -> String {
#[test] data_encoding::BASE64_NOPAD.encode(digest)
fn from_str_algo_missing() { }
nixhash::from_str(SHA256_BASE16, None).expect_err("must fail");
nixhash::from_str(SHA256_NIXBASE32, None).expect_err("must fail"); // TODO
nixhash::from_str(SHA256_BASE64, None).expect_err("must fail"); fn make_nixhash(algo: &HashAlgo, digest_encoded: String) -> String {
format!("{}:{}", algo, digest_encoded)
}
fn make_sri_string(algo: &HashAlgo, digest_encoded: String) -> String {
format!("{}-{}", algo, digest_encoded)
}
/// Test parsing a hash string in various formats, and also when/how the out-of-band algo is needed.
#[test_case(DIGEST_SHA1, HashAlgo::Sha1; "sha1")]
#[test_case(DIGEST_SHA256, HashAlgo::Sha256; "sha256")]
#[test_case(DIGEST_SHA512, HashAlgo::Sha512; "sha512")]
#[test_case(DIGEST_MD5, HashAlgo::Md5; "md5")]
fn from_str(digest: &[u8], algo: HashAlgo) {
let expected_hash = NixHash {
digest: digest.to_vec(),
algo: algo.clone(),
};
// parse SRI
{
// base64 without out-of-band algo
let s = make_sri_string(&algo, to_base64(digest));
let h = nixhash::from_str(&s, None).expect("must succeed");
assert_eq!(expected_hash, h);
// base64 with out-of-band-algo
let s = make_sri_string(&algo, to_base64(digest));
let h = nixhash::from_str(&s, Some(&algo.to_string())).expect("must succeed");
assert_eq!(expected_hash, h);
// base64_nopad without out-of-band algo
let s = make_sri_string(&algo, to_base64_nopad(digest));
let h = nixhash::from_str(&s, None).expect("must succeed");
assert_eq!(expected_hash, h);
// base64_nopad with out-of-band-algo
let s = make_sri_string(&algo, to_base64_nopad(digest));
let h = nixhash::from_str(&s, Some(&algo.to_string())).expect("must succeed");
assert_eq!(expected_hash, h);
}
// parse plain base16. should succeed with algo out-of-band, but fail without.
{
let s = to_base16(digest);
nixhash::from_str(&s, None).expect_err("must fail");
let h = nixhash::from_str(&s, Some(&algo.to_string())).expect("must succeed");
assert_eq!(expected_hash, h);
}
// parse plain nixbase32. should succeed with algo out-of-band, but fail without.
{
let s = to_nixbase32(digest);
nixhash::from_str(&s, None).expect_err("must fail");
let h = nixhash::from_str(&s, Some(&algo.to_string())).expect("must succeed");
assert_eq!(expected_hash, h);
}
// parse plain base64. should succeed with algo out-of-band, but fail without.
{
let s = to_base64(digest);
nixhash::from_str(&s, None).expect_err("must fail");
let h = nixhash::from_str(&s, Some(&algo.to_string())).expect("must succeed");
assert_eq!(expected_hash, h);
}
// parse Nix hash strings
{
// base16. should succeed with both algo out-of-band and in-band.
{
let s = make_nixhash(&algo, to_base16(digest));
assert_eq!(
expected_hash,
nixhash::from_str(&s, None).expect("must succeed")
);
assert_eq!(
expected_hash,
nixhash::from_str(&s, Some(&algo.to_string())).expect("must succeed")
);
}
// nixbase32. should succeed with both algo out-of-band and in-band.
{
let s = make_nixhash(&algo, to_nixbase32(digest));
assert_eq!(
expected_hash,
nixhash::from_str(&s, None).expect("must succeed")
);
assert_eq!(
expected_hash,
nixhash::from_str(&s, Some(&algo.to_string())).expect("must succeed")
);
}
// base64. should succeed with both algo out-of-band and in-band.
{
let s = make_nixhash(&algo, to_base64(digest));
assert_eq!(
expected_hash,
nixhash::from_str(&s, None).expect("must succeed")
);
assert_eq!(
expected_hash,
nixhash::from_str(&s, Some(&algo.to_string())).expect("must succeed")
);
}
}
} }
/// Test parsing an SRI hash via the [nixhash::from_sri_str] method. /// Test parsing an SRI hash via the [nixhash::from_sri_str] method.
@ -398,6 +465,6 @@ mod tests {
assert_eq!(&expected_digest, &nix_hash.digest); assert_eq!(&expected_digest, &nix_hash.digest);
// not passing SRI, but hash algo out of band should fail // not passing SRI, but hash algo out of band should fail
nixhash::from_str(&broken_base64, Some("sha256")).expect_err("must fail"); nixhash::from_str(broken_base64, Some("sha256")).expect_err("must fail");
} }
} }