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|
package http
import (
"bytes"
"context"
"encoding/base64"
"encoding/hex"
"errors"
"fmt"
"io"
"io/fs"
"net/http"
"sync"
castorev1pb "code.tvl.fyi/tvix/castore-go"
storev1pb "code.tvl.fyi/tvix/store-go"
"github.com/go-chi/chi/v5"
nixhash "github.com/nix-community/go-nix/pkg/hash"
"github.com/nix-community/go-nix/pkg/nixbase32"
log "github.com/sirupsen/logrus"
)
const (
narUrl = "/nar/{narhash:^([" + nixbase32.Alphabet + "]{52})$}.nar"
)
func renderNar(
ctx context.Context,
log *log.Entry,
directoryServiceClient castorev1pb.DirectoryServiceClient,
blobServiceClient castorev1pb.BlobServiceClient,
narHashDbMu *sync.Mutex,
narHashDb map[string]*narData,
w io.Writer,
narHash *nixhash.Hash,
headOnly bool,
) error {
// look in the lookup table
narHashDbMu.Lock()
narData, found := narHashDb[narHash.SRIString()]
narHashDbMu.Unlock()
rootNode := narData.rootNode
// if we didn't find anything, return 404.
if !found {
return fmt.Errorf("narHash not found: %w", fs.ErrNotExist)
}
// if this was only a head request, we're done.
if headOnly {
return nil
}
directories := make(map[string]*castorev1pb.Directory)
// If the root node is a directory, ask the directory service for all directories
if pathInfoDirectory := rootNode.GetDirectory(); pathInfoDirectory != nil {
rootDirectoryDigest := pathInfoDirectory.GetDigest()
log = log.WithField("root_directory", base64.StdEncoding.EncodeToString(rootDirectoryDigest))
directoryStream, err := directoryServiceClient.Get(ctx, &castorev1pb.GetDirectoryRequest{
ByWhat: &castorev1pb.GetDirectoryRequest_Digest{
Digest: rootDirectoryDigest,
},
Recursive: true,
})
if err != nil {
return fmt.Errorf("unable to query directory stream: %w", err)
}
// For now, we just stream all of these locally and put them into a hashmap,
// which is used in the lookup function below.
for {
directory, err := directoryStream.Recv()
if err != nil {
if err == io.EOF {
break
}
return fmt.Errorf("unable to receive from directory stream: %w", err)
}
// calculate directory digest
// TODO: do we need to do any more validation?
directoryDgst, err := directory.Digest()
if err != nil {
return fmt.Errorf("unable to calculate directory digest: %w", err)
}
log.WithField("directory", base64.StdEncoding.EncodeToString(directoryDgst)).Debug("received directory node")
directories[hex.EncodeToString(directoryDgst)] = directory
}
}
// render the NAR file
err := storev1pb.Export(
w,
rootNode,
func(directoryDigest []byte) (*castorev1pb.Directory, error) {
log.WithField("directory", base64.StdEncoding.EncodeToString(directoryDigest)).Debug("Get directory")
directoryRefStr := hex.EncodeToString(directoryDigest)
directory, found := directories[directoryRefStr]
if !found {
return nil, fmt.Errorf(
"directory with hash %v does not exist: %w",
directoryDigest,
fs.ErrNotExist,
)
}
return directory, nil
},
func(blobDigest []byte) (io.ReadCloser, error) {
log.WithField("blob", base64.StdEncoding.EncodeToString(blobDigest)).Debug("Get blob")
resp, err := blobServiceClient.Read(ctx, &castorev1pb.ReadBlobRequest{
Digest: blobDigest,
})
if err != nil {
return nil, fmt.Errorf("unable to get blob: %w", err)
}
// set up a pipe, let a goroutine write, return the reader.
pR, pW := io.Pipe()
go func() {
for {
chunk, err := resp.Recv()
if errors.Is(err, io.EOF) {
break
}
if err != nil {
pW.CloseWithError(fmt.Errorf("receiving chunk: %w", err))
return
}
// write the received chunk to the writer part of the pipe
if _, err := io.Copy(pW, bytes.NewReader(chunk.GetData())); err != nil {
log.WithError(err).Error("writing chunk to pipe")
pW.CloseWithError(fmt.Errorf("writing chunk to pipe: %w", err))
return
}
}
pW.Close()
}()
return io.NopCloser(pR), nil
},
)
if err != nil {
return fmt.Errorf("unable to export nar: %w", err)
}
return nil
}
func registerNarGet(s *Server) {
// produce a handler for rendering NAR files.
genNarHandler := func(isHead bool) func(w http.ResponseWriter, r *http.Request) {
return func(w http.ResponseWriter, r *http.Request) {
defer r.Body.Close()
ctx := r.Context()
// parse the narhash sent in the request URL
narHash, err := parseNarHashFromUrl(chi.URLParamFromCtx(ctx, "narhash"))
if err != nil {
log.WithError(err).WithField("url", r.URL).Error("unable to decode nar hash from url")
w.WriteHeader(http.StatusBadRequest)
_, err := w.Write([]byte("unable to decode nar hash from url"))
if err != nil {
log.WithError(err).Errorf("unable to write error message to client")
}
return
}
log := log.WithField("narhash_url", narHash.SRIString())
// TODO: inline more of that function here?
err = renderNar(ctx, log, s.directoryServiceClient, s.blobServiceClient, &s.narDbMu, s.narDb, w, narHash, isHead)
if err != nil {
if errors.Is(err, fs.ErrNotExist) {
w.WriteHeader(http.StatusNotFound)
} else {
log.WithError(err).Warn("unable to render nar")
w.WriteHeader(http.StatusInternalServerError)
}
}
}
}
s.handler.Head(narUrl, genNarHandler(true))
s.handler.Get(narUrl, genNarHandler(false))
}
|
