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Diffstat (limited to 'tvix/nix-compat/src/narinfo.rs')
| -rw-r--r-- | tvix/nix-compat/src/narinfo.rs | 406 |
1 files changed, 406 insertions, 0 deletions
diff --git a/tvix/nix-compat/src/narinfo.rs b/tvix/nix-compat/src/narinfo.rs new file mode 100644 index 000000000000..a66709abfe79 --- /dev/null +++ b/tvix/nix-compat/src/narinfo.rs @@ -0,0 +1,406 @@ +//! NAR info files describe a store path in a traditional Nix binary cache. +//! Over the wire, they are formatted as "Key: value" pairs separated by newlines. +//! +//! It contains four kinds of information: +//! 1. the description of the store path itself +//! * store path prefix, digest, and name +//! * NAR hash and size +//! * references +//! 2. authenticity information +//! * zero or more signatures over that description +//! * an optional [CAHash] for content-addressed paths (fixed outputs, sources, and derivations) +//! 3. derivation metadata +//! * deriver (the derivation that produced this path) +//! * system (the system value of that derivation) +//! 4. cache-specific information +//! * URL of the compressed NAR, relative to the NAR info file +//! * compression algorithm used for the NAR +//! * hash and size of the compressed NAR + +use data_encoding::BASE64; +use std::{ + fmt::{self, Display}, + mem, +}; + +use crate::{ + nixbase32, + nixhash::{CAHash, NixHash}, + store_path::StorePathRef, +}; + +#[derive(Debug)] +pub struct NarInfo<'a> { + // core (authenticated, but unverified here) + /// Store path described by this [NarInfo] + pub store_path: StorePathRef<'a>, + /// SHA-256 digest of the NAR file + pub nar_hash: [u8; 32], + /// Size of the NAR file in bytes + pub nar_size: u64, + /// Store paths known to be referenced by the contents + pub references: Vec<StorePathRef<'a>>, + // authenticity + /// Ed25519 signature over the path fingerprint + pub signatures: Vec<Signature<'a>>, + /// Content address (for content-defined paths) + pub ca: Option<CAHash>, + // derivation metadata + /// Nix system triple of [deriver] + pub system: Option<&'a str>, + /// Store path of the derivation that produced this + pub deriver: Option<StorePathRef<'a>>, + // cache-specific untrusted metadata + /// Relative URL of the compressed NAR file + pub url: &'a str, + /// Compression method of the NAR file + /// TODO(edef): default this to bzip2, and have None mean "none" (uncompressed) + pub compression: Option<&'a str>, + /// SHA-256 digest of the file at `url` + pub file_hash: Option<[u8; 32]>, + /// Size of the file at `url` in bytes + pub file_size: Option<u64>, +} + +impl<'a> NarInfo<'a> { + pub fn parse(input: &'a str) -> Option<Self> { + let mut store_path = None; + let mut url = None; + let mut compression = None; + let mut file_hash = None; + let mut file_size = None; + let mut nar_hash = None; + let mut nar_size = None; + let mut references = None; + let mut system = None; + let mut deriver = None; + let mut signatures = vec![]; + let mut ca = None; + + for line in input.lines() { + let (tag, val) = line.split_once(':')?; + let val = val.strip_prefix(' ')?; + + match tag { + "StorePath" => { + let val = val.strip_prefix("/nix/store/")?; + let val = StorePathRef::from_bytes(val.as_bytes()).ok()?; + + if store_path.replace(val).is_some() { + return None; + } + } + "URL" => { + if val.is_empty() { + return None; + } + + if url.replace(val).is_some() { + return None; + } + } + "Compression" => { + if val.is_empty() { + return None; + } + + if compression.replace(val).is_some() { + return None; + } + } + "FileHash" => { + let val = val.strip_prefix("sha256:")?; + let val = nixbase32::decode_fixed::<32>(val).ok()?; + + if file_hash.replace(val).is_some() { + return None; + } + } + "FileSize" => { + let val = val.parse::<u64>().ok()?; + + if file_size.replace(val).is_some() { + return None; + } + } + "NarHash" => { + let val = val.strip_prefix("sha256:")?; + let val = nixbase32::decode_fixed::<32>(val).ok()?; + + if nar_hash.replace(val).is_some() { + return None; + } + } + "NarSize" => { + let val = val.parse::<u64>().ok()?; + + if nar_size.replace(val).is_some() { + return None; + } + } + "References" => { + let val: Vec<StorePathRef> = if !val.is_empty() { + let mut prev = ""; + val.split(' ') + .map(|s| { + if mem::replace(&mut prev, s) < s { + StorePathRef::from_bytes(s.as_bytes()).ok() + } else { + // references are out of order + None + } + }) + .collect::<Option<_>>()? + } else { + vec![] + }; + + if references.replace(val).is_some() { + return None; + } + } + "System" => { + if val.is_empty() { + return None; + } + + if system.replace(val).is_some() { + return None; + } + } + "Deriver" => { + let val = StorePathRef::from_bytes(val.as_bytes()).ok()?; + + if !val.name().ends_with(".drv") { + return None; + } + + if deriver.replace(val).is_some() { + return None; + } + } + "Sig" => { + let val = Signature::parse(val)?; + + signatures.push(val); + } + "CA" => { + let val = parse_ca(val)?; + + if ca.replace(val).is_some() { + return None; + } + } + _ => { + // unknown field, ignore + } + } + } + + Some(NarInfo { + store_path: store_path?, + nar_hash: nar_hash?, + nar_size: nar_size?, + references: references?, + signatures, + ca, + system, + deriver, + url: url?, + compression, + file_hash, + file_size, + }) + } +} + +impl Display for NarInfo<'_> { + fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result { + writeln!(w, "StorePath: /nix/store/{}", self.store_path)?; + writeln!(w, "URL: {}", self.url)?; + + if let Some(compression) = self.compression { + writeln!(w, "Compression: {compression}")?; + } + + if let Some(file_hash) = self.file_hash { + writeln!(w, "FileHash: {}", fmt_hash(&NixHash::Sha256(file_hash)))?; + } + + if let Some(file_size) = self.file_size { + writeln!(w, "FileSize: {file_size}")?; + } + + writeln!(w, "NarHash: {}", fmt_hash(&NixHash::Sha256(self.nar_hash)))?; + writeln!(w, "NarSize: {}", self.nar_size)?; + + write!(w, "References:")?; + if self.references.is_empty() { + write!(w, " ")?; + } else { + for path in &self.references { + write!(w, " {path}")?; + } + } + writeln!(w)?; + + if let Some(deriver) = &self.deriver { + writeln!(w, "Deriver: {deriver}")?; + } + + if let Some(system) = self.system { + writeln!(w, "System: {system}")?; + } + + for sig in &self.signatures { + writeln!(w, "Sig: {sig}")?; + } + + if let Some(ca) = &self.ca { + writeln!(w, "CA: {}", fmt_ca(ca))?; + } + + Ok(()) + } +} + +#[derive(Debug)] +pub struct Signature<'a> { + name: &'a str, + bytes: [u8; 64], +} + +impl<'a> Signature<'a> { + pub fn parse(input: &'a str) -> Option<Signature<'a>> { + let (name, bytes64) = input.split_once(':')?; + + let mut buf = [0; 66]; + let mut bytes = [0; 64]; + match BASE64.decode_mut(bytes64.as_bytes(), &mut buf) { + Ok(64) => { + bytes.copy_from_slice(&buf[..64]); + } + _ => { + return None; + } + } + + Some(Signature { name, bytes }) + } + + pub fn name(&self) -> &'a str { + self.name + } + + pub fn bytes(&self) -> &[u8; 64] { + &self.bytes + } +} + +impl Display for Signature<'_> { + fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result { + write!(w, "{}:{}", self.name, BASE64.encode(&self.bytes)) + } +} + +pub fn parse_ca(s: &str) -> Option<CAHash> { + let (tag, s) = s.split_once(':')?; + + match tag { + "text" => { + let digest = s.strip_prefix("sha256:")?; + let digest = nixbase32::decode_fixed(digest).ok()?; + Some(CAHash::Text(digest)) + } + "fixed" => { + if let Some(digest) = s.strip_prefix("r:sha256:") { + let digest = nixbase32::decode_fixed(digest).ok()?; + Some(CAHash::Nar(NixHash::Sha256(digest))) + } else { + parse_hash(s).map(CAHash::Flat) + } + } + _ => None, + } +} + +#[allow(non_camel_case_types)] +struct fmt_ca<'a>(&'a CAHash); + +impl Display for fmt_ca<'_> { + fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result { + match self.0 { + CAHash::Flat(h) => { + write!(w, "fixed:{}", fmt_hash(h)) + } + &CAHash::Text(d) => { + write!(w, "text:{}", fmt_hash(&NixHash::Sha256(d))) + } + CAHash::Nar(h) => { + write!(w, "fixed:r:{}", fmt_hash(h)) + } + } + } +} + +fn parse_hash(s: &str) -> Option<NixHash> { + let (tag, digest) = s.split_once(':')?; + + (match tag { + "md5" => nixbase32::decode_fixed(digest).map(NixHash::Md5), + "sha1" => nixbase32::decode_fixed(digest).map(NixHash::Sha1), + "sha256" => nixbase32::decode_fixed(digest).map(NixHash::Sha256), + "sha512" => nixbase32::decode_fixed(digest) + .map(Box::new) + .map(NixHash::Sha512), + _ => return None, + }) + .ok() +} + +#[allow(non_camel_case_types)] +struct fmt_hash<'a>(&'a NixHash); + +impl Display for fmt_hash<'_> { + fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result { + let (tag, digest) = match self.0 { + NixHash::Md5(d) => ("md5", &d[..]), + NixHash::Sha1(d) => ("sha1", &d[..]), + NixHash::Sha256(d) => ("sha256", &d[..]), + NixHash::Sha512(d) => ("sha512", &d[..]), + }; + + write!(w, "{tag}:{}", nixbase32::encode(digest)) + } +} + +#[cfg(test)] +mod test { + use lazy_static::lazy_static; + use pretty_assertions::assert_eq; + use std::{io, str}; + + use super::NarInfo; + + lazy_static! { + static ref CASES: &'static [&'static str] = { + let data = zstd::decode_all(io::Cursor::new(include_bytes!("../testdata/narinfo.zst"))) + .unwrap(); + let data = str::from_utf8(Vec::leak(data)).unwrap(); + Vec::leak( + data.split_inclusive("\n\n") + .map(|s| s.strip_suffix('\n').unwrap()) + .collect::<Vec<_>>(), + ) + }; + } + + #[test] + fn roundtrip() { + for &input in *CASES { + let parsed = NarInfo::parse(input).expect("should parse"); + let output = format!("{parsed}"); + assert_eq!(input, output, "should roundtrip"); + } + } +} |