use std::{
io::{self, BufRead, Read, Write},
pin::Pin,
};
use data_encoding::BASE64;
use futures::{Stream, TryStreamExt};
use nix_compat::{
narinfo::{self, NarInfo},
nixbase32,
};
use reqwest::StatusCode;
use sha2::{digest::FixedOutput, Digest, Sha256};
use tonic::async_trait;
use tracing::{debug, instrument, warn};
use tvix_castore::{
blobservice::BlobService, directoryservice::DirectoryService, proto as castorepb, Error,
};
use crate::proto::PathInfo;
use super::PathInfoService;
/// NixHTTPPathInfoService acts as a bridge in between the Nix HTTP Binary cache
/// protocol provided by Nix binary caches such as cache.nixos.org, and the Tvix
/// Store Model.
/// It implements the [PathInfoService] trait in an interesting way:
/// Every [PathInfoService::get] fetches the .narinfo and referred NAR file,
/// inserting components into a [BlobService] and [DirectoryService], then
/// returning a [PathInfo] struct with the root.
///
/// Due to this being quite a costly operation, clients are expected to layer
/// this service with store composition, so they're only ingested once.
///
/// The client is expected to be (indirectly) using the same [BlobService] and
/// [DirectoryService], so able to fetch referred Directories and Blobs.
/// [PathInfoService::put] and [PathInfoService::calculate_nar] are not
/// implemented and return an error if called.
/// TODO: what about reading from nix-cache-info?
pub struct NixHTTPPathInfoService<BS, DS> {
base_url: url::Url,
http_client: reqwest::Client,
blob_service: BS,
directory_service: DS,
/// An optional list of [narinfo::PubKey].
/// If set, the .narinfo files received need to have correct signature by at least one of these.
public_keys: Option<Vec<narinfo::PubKey>>,
}
impl<BS, DS> NixHTTPPathInfoService<BS, DS> {
pub fn new(base_url: url::Url, blob_service: BS, directory_service: DS) -> Self {
Self {
base_url,
http_client: reqwest::Client::new(),
blob_service,
directory_service,
public_keys: None,
}
}
/// Configures [Self] to validate NARInfo fingerprints with the public keys passed.
pub fn set_public_keys(&mut self, public_keys: Vec<narinfo::PubKey>) {
self.public_keys = Some(public_keys);
}
}
#[async_trait]
impl<BS, DS> PathInfoService for NixHTTPPathInfoService<BS, DS>
where
BS: AsRef<dyn BlobService> + Send + Sync + Clone + 'static,
DS: AsRef<dyn DirectoryService> + Send + Sync + Clone + 'static,
{
#[instrument(skip_all, err, fields(path.digest=BASE64.encode(&digest)))]
async fn get(&self, digest: [u8; 20]) -> Result<Option<PathInfo>, Error> {
let narinfo_url = self
.base_url
.join(&format!("{}.narinfo", nixbase32::encode(&digest)))
.map_err(|e| {
warn!(e = %e, "unable to join URL");
io::Error::new(io::ErrorKind::InvalidInput, "unable to join url")
})?;
debug!(narinfo_url= %narinfo_url, "constructed NARInfo url");
let resp = self
.http_client
.get(narinfo_url)
.send()
.await
.map_err(|e| {
warn!(e=%e,"unable to send NARInfo request");
io::Error::new(
io::ErrorKind::InvalidInput,
"unable to send NARInfo request",
)
})?;
// In the case of a 404, return a NotFound.
// We also return a NotFound in case of a 403 - this is to match the behaviour as Nix,
// when querying nix-cache.s3.amazonaws.com directly, rather than cache.nixos.org.
if resp.status() == StatusCode::NOT_FOUND || resp.status() == StatusCode::FORBIDDEN {
return Ok(None);
}
let narinfo_str = resp.text().await.map_err(|e| {
warn!(e=%e,"unable to decode response as string");
io::Error::new(
io::ErrorKind::InvalidData,
"unable to decode response as string",
)
})?;
// parse the received narinfo
let narinfo = NarInfo::parse(&narinfo_str).map_err(|e| {
warn!(e=%e,"unable to parse response as NarInfo");
io::Error::new(
io::ErrorKind::InvalidData,
"unable to parse response as NarInfo",
)
})?;
// if [self.public_keys] is set, ensure there's at least one valid signature.
if let Some(public_keys) = &self.public_keys {
let fingerprint = narinfo.fingerprint();
if !public_keys.iter().any(|pubkey| {
narinfo
.signatures
.iter()
.any(|sig| pubkey.verify(&fingerprint, sig))
}) {
warn!("no valid signature found");
Err(io::Error::new(
io::ErrorKind::InvalidData,
"no valid signature found",
))?;
}
}
// Convert to a (sparse) PathInfo. We still need to populate the node field,
// and for this we need to download the NAR file.
// FUTUREWORK: Keep some database around mapping from narsha256 to
// (unnamed) rootnode, so we can use that (and the name from the
// StorePath) and avoid downloading the same NAR a second time.
let pathinfo: PathInfo = (&narinfo).into();
// create a request for the NAR file itself.
let nar_url = self.base_url.join(narinfo.url).map_err(|e| {
warn!(e = %e, "unable to join URL");
io::Error::new(io::ErrorKind::InvalidInput, "unable to join url")
})?;
debug!(nar_url= %nar_url, "constructed NAR url");
let resp = self
.http_client
.get(nar_url.clone())
.send()
.await
.map_err(|e| {
warn!(e=%e,"unable to send NAR request");
io::Error::new(io::ErrorKind::InvalidInput, "unable to send NAR request")
})?;
// if the request is not successful, return an error.
if !resp.status().is_success() {
return Err(Error::StorageError(format!(
"unable to retrieve NAR at {}, status {}",
nar_url,
resp.status()
)));
}
// get an AsyncRead of the response body.
let async_r = tokio_util::io::StreamReader::new(resp.bytes_stream().map_err(|e| {
let e = e.without_url();
warn!(e=%e, "failed to get response body");
io::Error::new(io::ErrorKind::BrokenPipe, e.to_string())
}));
let sync_r = tokio_util::io::SyncIoBridge::new(async_r);
// handle decompression, by wrapping the reader.
let sync_r: Box<dyn BufRead + Send> = match narinfo.compression {
Some("none") => Box::new(sync_r),
Some("xz") => Box::new(io::BufReader::new(xz2::read::XzDecoder::new(sync_r))),
Some(comp) => {
return Err(Error::InvalidRequest(
format!("unsupported compression: {}", comp).to_string(),
))
}
None => {
return Err(Error::InvalidRequest(
"unsupported compression: bzip2".to_string(),
))
}
};
let res = tokio::task::spawn_blocking({
let blob_service = self.blob_service.clone();
let directory_service = self.directory_service.clone();
move || -> io::Result<_> {
// Wrap the reader once more, so we can calculate NarSize and NarHash
let mut sync_r = io::BufReader::new(NarReader::from(sync_r));
let root_node = crate::nar::read_nar(&mut sync_r, blob_service, directory_service)?;
let (_, nar_hash, nar_size) = sync_r.into_inner().into_inner();
Ok((root_node, nar_hash, nar_size))
}
})
.await
.unwrap();
match res {
Ok((root_node, nar_hash, nar_size)) => {
// ensure the ingested narhash and narsize do actually match.
if narinfo.nar_size != nar_size {
warn!(
narinfo.nar_size = narinfo.nar_size,
http.nar_size = nar_size,
"NARSize mismatch"
);
Err(io::Error::new(
io::ErrorKind::InvalidData,
"NarSize mismatch".to_string(),
))?;
} else if narinfo.nar_hash != nar_hash {
warn!(
narinfo.nar_hash = BASE64.encode(&narinfo.nar_hash),
http.nar_hash = BASE64.encode(&nar_hash),
"NarHash mismatch"
);
Err(io::Error::new(
io::ErrorKind::InvalidData,
"NarHash mismatch".to_string(),
))?;
}
Ok(Some(PathInfo {
node: Some(castorepb::Node {
// set the name of the root node to the digest-name of the store path.
node: Some(
root_node.rename(narinfo.store_path.to_string().to_owned().into()),
),
}),
references: pathinfo.references,
narinfo: pathinfo.narinfo,
}))
}
Err(e) => Err(e.into()),
}
}
#[instrument(skip_all, fields(path_info=?_path_info))]
async fn put(&self, _path_info: PathInfo) -> Result<PathInfo, Error> {
Err(Error::InvalidRequest(
"put not supported for this backend".to_string(),
))
}
#[instrument(skip_all, fields(root_node=?root_node))]
async fn calculate_nar(
&self,
root_node: &castorepb::node::Node,
) -> Result<(u64, [u8; 32]), Error> {
Err(Error::InvalidRequest(
"calculate_nar not supported for this backend".to_string(),
))
}
fn list(&self) -> Pin<Box<dyn Stream<Item = Result<PathInfo, Error>> + Send>> {
Box::pin(futures::stream::once(async {
Err(Error::InvalidRequest(
"list not supported for this backend".to_string(),
))
}))
}
}
/// Small helper reader implementing [std::io::Read].
/// It can be used to wrap another reader, counts the number of bytes read
/// and the sha256 digest of the contents.
struct NarReader<R: Read> {
r: R,
sha256: sha2::Sha256,
bytes_read: u64,
}
impl<R: Read> NarReader<R> {
pub fn from(inner: R) -> Self {
Self {
r: inner,
sha256: Sha256::new(),
bytes_read: 0,
}
}
/// Returns the (remaining) inner reader, the sha256 digest and the number of bytes read.
pub fn into_inner(self) -> (R, [u8; 32], u64) {
(self.r, self.sha256.finalize_fixed().into(), self.bytes_read)
}
}
impl<R: Read> Read for NarReader<R> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
self.r.read(buf).map(|n| {
self.bytes_read += n as u64;
self.sha256.write_all(&buf[..n]).unwrap();
n
})
}
}
