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-rw-r--r--tvix/nar-bridge-go/pkg/http/nar_get.go197
-rw-r--r--tvix/nar-bridge-go/pkg/http/nar_put.go141
-rw-r--r--tvix/nar-bridge-go/pkg/http/narinfo.go51
-rw-r--r--tvix/nar-bridge-go/pkg/http/narinfo_get.go137
-rw-r--r--tvix/nar-bridge-go/pkg/http/narinfo_put.go103
-rw-r--r--tvix/nar-bridge-go/pkg/http/server.go119
-rw-r--r--tvix/nar-bridge-go/pkg/http/util.go24
7 files changed, 772 insertions, 0 deletions
diff --git a/tvix/nar-bridge-go/pkg/http/nar_get.go b/tvix/nar-bridge-go/pkg/http/nar_get.go
new file mode 100644
index 000000000000..75797f8da90e
--- /dev/null
+++ b/tvix/nar-bridge-go/pkg/http/nar_get.go
@@ -0,0 +1,197 @@
+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))
+}
diff --git a/tvix/nar-bridge-go/pkg/http/nar_put.go b/tvix/nar-bridge-go/pkg/http/nar_put.go
new file mode 100644
index 000000000000..96bdd38b709d
--- /dev/null
+++ b/tvix/nar-bridge-go/pkg/http/nar_put.go
@@ -0,0 +1,141 @@
+package http
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"net/http"
+
+	castorev1pb "code.tvl.fyi/tvix/castore-go"
+	"code.tvl.fyi/tvix/nar-bridge-go/pkg/importer"
+	"github.com/go-chi/chi/v5"
+	mh "github.com/multiformats/go-multihash/core"
+	nixhash "github.com/nix-community/go-nix/pkg/hash"
+	"github.com/sirupsen/logrus"
+	log "github.com/sirupsen/logrus"
+)
+
+func registerNarPut(s *Server) {
+	s.handler.Put(narUrl, func(w http.ResponseWriter, r *http.Request) {
+		defer r.Body.Close()
+
+		ctx := r.Context()
+
+		// parse the narhash sent in the request URL
+		narHashFromUrl, 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).Error("unable to write error message to client")
+			}
+
+			return
+		}
+
+		log := log.WithField("narhash_url", narHashFromUrl.SRIString())
+
+		directoriesUploader := importer.NewDirectoriesUploader(ctx, s.directoryServiceClient)
+		defer directoriesUploader.Done() //nolint:errcheck
+
+		rootNode, narSize, narSha256, err := importer.Import(
+			ctx,
+			// buffer the body by 10MiB
+			bufio.NewReaderSize(r.Body, 10*1024*1024),
+			importer.GenBlobUploaderCb(ctx, s.blobServiceClient),
+			func(directory *castorev1pb.Directory) ([]byte, error) {
+				return directoriesUploader.Put(directory)
+			},
+		)
+
+		if err != nil {
+			log.Errorf("error during NAR import: %v", err)
+			w.WriteHeader(http.StatusInternalServerError)
+			_, err := w.Write([]byte(fmt.Sprintf("error during NAR import: %v", err)))
+			if err != nil {
+				log.WithError(err).Errorf("unable to write error message to client")
+			}
+
+			return
+		}
+
+		log.Debug("closing the stream")
+
+		// Close the directories uploader
+		directoriesPutResponse, err := directoriesUploader.Done()
+		if err != nil {
+			log.WithError(err).Error("error during directory upload")
+			w.WriteHeader(http.StatusBadRequest)
+			_, err := w.Write([]byte("error during directory upload"))
+			if err != nil {
+				log.WithError(err).Errorf("unable to write error message to client")
+			}
+
+			return
+		}
+		// If we uploaded directories (so directoriesPutResponse doesn't return null),
+		// the RootDigest field in directoriesPutResponse should match the digest
+		// returned in the PathInfo struct returned by the `Import` call.
+		// This check ensures the server-side came up with the same root hash.
+
+		if directoriesPutResponse != nil {
+			rootDigestPathInfo := rootNode.GetDirectory().GetDigest()
+			rootDigestDirectoriesPutResponse := directoriesPutResponse.GetRootDigest()
+
+			log := log.WithFields(logrus.Fields{
+				"root_digest_pathinfo":             rootDigestPathInfo,
+				"root_digest_directories_put_resp": rootDigestDirectoriesPutResponse,
+			})
+			if !bytes.Equal(rootDigestPathInfo, rootDigestDirectoriesPutResponse) {
+				log.Errorf("returned root digest doesn't match what's calculated")
+
+				w.WriteHeader(http.StatusBadRequest)
+				_, err := w.Write([]byte("error in root digest calculation"))
+				if err != nil {
+					log.WithError(err).Error("unable to write error message to client")
+				}
+
+				return
+			}
+		}
+
+		// Compare the nar hash specified in the URL with the one that has been
+		// calculated while processing the NAR file.
+		narHash, err := nixhash.FromHashTypeAndDigest(mh.SHA2_256, narSha256)
+		if err != nil {
+			panic("must parse nixbase32")
+		}
+
+		if !bytes.Equal(narHashFromUrl.Digest(), narHash.Digest()) {
+			log := log.WithFields(logrus.Fields{
+				"narhash_received_sha256": narHash.SRIString(),
+				"narsize":                 narSize,
+			})
+			log.Error("received bytes don't match narhash from URL")
+
+			w.WriteHeader(http.StatusBadRequest)
+			_, err := w.Write([]byte("received bytes don't match narHash specified in URL"))
+			if err != nil {
+				log.WithError(err).Errorf("unable to write error message to client")
+			}
+
+			return
+		}
+
+		// Insert the partial pathinfo structs into our lookup map,
+		// so requesting the NAR file will be possible.
+		// The same  might exist already, but it'll have the same contents (so
+		// replacing will be a no-op), except maybe the root node Name field value, which
+		// is safe to ignore (as not part of the NAR).
+		s.narDbMu.Lock()
+		s.narDb[narHash.SRIString()] = &narData{
+			rootNode: rootNode,
+			narSize:  narSize,
+		}
+		s.narDbMu.Unlock()
+
+		// Done!
+	})
+
+}
diff --git a/tvix/nar-bridge-go/pkg/http/narinfo.go b/tvix/nar-bridge-go/pkg/http/narinfo.go
new file mode 100644
index 000000000000..e5b99a9505f1
--- /dev/null
+++ b/tvix/nar-bridge-go/pkg/http/narinfo.go
@@ -0,0 +1,51 @@
+package http
+
+import (
+	"fmt"
+
+	storev1pb "code.tvl.fyi/tvix/store-go"
+	mh "github.com/multiformats/go-multihash/core"
+	nixhash "github.com/nix-community/go-nix/pkg/hash"
+
+	"github.com/nix-community/go-nix/pkg/narinfo"
+	"github.com/nix-community/go-nix/pkg/narinfo/signature"
+	"github.com/nix-community/go-nix/pkg/nixbase32"
+)
+
+// ToNixNarInfo converts the PathInfo to a narinfo.NarInfo.
+func ToNixNarInfo(p *storev1pb.PathInfo) (*narinfo.NarInfo, error) {
+	// ensure the PathInfo is valid, and extract the StorePath from the node in
+	// there.
+	storePath, err := p.Validate()
+	if err != nil {
+		return nil, fmt.Errorf("failed to validate PathInfo: %w", err)
+	}
+
+	// convert the signatures from storev1pb signatures to narinfo signatures
+	narinfoSignatures := make([]signature.Signature, len(p.GetNarinfo().GetSignatures()))
+	for i, pathInfoSignature := range p.GetNarinfo().GetSignatures() {
+		narinfoSignatures[i] = signature.Signature{
+			Name: pathInfoSignature.GetName(),
+			Data: pathInfoSignature.GetData(),
+		}
+	}
+
+	// produce nixhash for the narsha256.
+	narHash, err := nixhash.FromHashTypeAndDigest(
+		mh.SHA2_256,
+		p.GetNarinfo().GetNarSha256(),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("invalid narsha256: %w", err)
+	}
+
+	return &narinfo.NarInfo{
+		StorePath:   storePath.Absolute(),
+		URL:         "nar/" + nixbase32.EncodeToString(narHash.Digest()) + ".nar",
+		Compression: "none",
+		NarHash:     narHash,
+		NarSize:     uint64(p.GetNarinfo().GetNarSize()),
+		References:  p.GetNarinfo().GetReferenceNames(),
+		Signatures:  narinfoSignatures,
+	}, nil
+}
diff --git a/tvix/nar-bridge-go/pkg/http/narinfo_get.go b/tvix/nar-bridge-go/pkg/http/narinfo_get.go
new file mode 100644
index 000000000000..d43cb58078da
--- /dev/null
+++ b/tvix/nar-bridge-go/pkg/http/narinfo_get.go
@@ -0,0 +1,137 @@
+package http
+
+import (
+	"context"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"net/http"
+	"strings"
+	"sync"
+
+	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"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+// renderNarinfo writes narinfo contents to a passed io.Writer, or a returns a
+// (wrapped) io.ErrNoExist error if something doesn't exist.
+// if headOnly is set to true, only the existence is checked, but no content is
+// actually written.
+func renderNarinfo(
+	ctx context.Context,
+	log *log.Entry,
+	pathInfoServiceClient storev1pb.PathInfoServiceClient,
+	narHashToPathInfoMu *sync.Mutex,
+	narHashToPathInfo map[string]*narData,
+	outputHash []byte,
+	w io.Writer,
+	headOnly bool,
+) error {
+	pathInfo, err := pathInfoServiceClient.Get(ctx, &storev1pb.GetPathInfoRequest{
+		ByWhat: &storev1pb.GetPathInfoRequest_ByOutputHash{
+			ByOutputHash: outputHash,
+		},
+	})
+	if err != nil {
+		st, ok := status.FromError(err)
+		if ok {
+			if st.Code() == codes.NotFound {
+				return fmt.Errorf("output hash %v not found: %w", base64.StdEncoding.EncodeToString(outputHash), fs.ErrNotExist)
+			}
+			return fmt.Errorf("unable to get pathinfo, code %v: %w", st.Code(), err)
+		}
+
+		return fmt.Errorf("unable to get pathinfo: %w", err)
+	}
+
+	log = log.WithField("pathInfo", pathInfo)
+
+	if _, err := pathInfo.Validate(); err != nil {
+		log.WithError(err).Error("unable to validate PathInfo")
+
+		return fmt.Errorf("unable to validate PathInfo: %w", err)
+	}
+
+	if pathInfo.GetNarinfo() == nil {
+		log.Error("PathInfo doesn't contain Narinfo field")
+
+		return fmt.Errorf("PathInfo doesn't contain Narinfo field")
+	}
+
+	// extract the NARHash. This must succeed, as Validate() did succeed.
+	narHash, err := nixhash.FromHashTypeAndDigest(0x12, pathInfo.GetNarinfo().GetNarSha256())
+	if err != nil {
+		panic("must parse NarHash")
+	}
+
+	// add things to the lookup table, in case the same process didn't handle the NAR hash yet.
+	narHashToPathInfoMu.Lock()
+	narHashToPathInfo[narHash.SRIString()] = &narData{
+		rootNode: pathInfo.GetNode(),
+		narSize:  pathInfo.GetNarinfo().GetNarSize(),
+	}
+	narHashToPathInfoMu.Unlock()
+
+	if headOnly {
+		return nil
+	}
+
+	// convert the PathInfo to NARInfo.
+	narInfo, err := ToNixNarInfo(pathInfo)
+
+	// Write it out to the client.
+	_, err = io.Copy(w, strings.NewReader(narInfo.String()))
+	if err != nil {
+		return fmt.Errorf("unable to write narinfo to client: %w", err)
+	}
+
+	return nil
+}
+
+func registerNarinfoGet(s *Server) {
+	// GET/HEAD $outHash.narinfo looks up the PathInfo from the tvix-store,
+	// and, if it's a GET request, render a .narinfo file to the client.
+	// In both cases it will keep the PathInfo in the lookup map,
+	// so a subsequent GET/HEAD /nar/ $narhash.nar request can find it.
+	genNarinfoHandler := 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()
+			log := log.WithField("outputhash", chi.URLParamFromCtx(ctx, "outputhash"))
+
+			// parse the output hash sent in the request URL
+			outputHash, err := nixbase32.DecodeString(chi.URLParamFromCtx(ctx, "outputhash"))
+			if err != nil {
+				log.WithError(err).Error("unable to decode output hash from url")
+				w.WriteHeader(http.StatusBadRequest)
+				_, err := w.Write([]byte("unable to decode output hash from url"))
+				if err != nil {
+					log.WithError(err).Errorf("unable to write error message to client")
+				}
+
+				return
+			}
+
+			err = renderNarinfo(ctx, log, s.pathInfoServiceClient, &s.narDbMu, s.narDb, outputHash, w, isHead)
+			if err != nil {
+				if errors.Is(err, fs.ErrNotExist) {
+					w.WriteHeader(http.StatusNotFound)
+				} else {
+					log.WithError(err).Warn("unable to render narinfo")
+					w.WriteHeader(http.StatusInternalServerError)
+				}
+			}
+		}
+	}
+
+	s.handler.Get("/{outputhash:^["+nixbase32.Alphabet+"]{32}}.narinfo", genNarinfoHandler(false))
+	s.handler.Head("/{outputhash:^["+nixbase32.Alphabet+"]{32}}.narinfo", genNarinfoHandler(true))
+}
diff --git a/tvix/nar-bridge-go/pkg/http/narinfo_put.go b/tvix/nar-bridge-go/pkg/http/narinfo_put.go
new file mode 100644
index 000000000000..0e2ae989c039
--- /dev/null
+++ b/tvix/nar-bridge-go/pkg/http/narinfo_put.go
@@ -0,0 +1,103 @@
+package http
+
+import (
+	"net/http"
+
+	"code.tvl.fyi/tvix/nar-bridge-go/pkg/importer"
+	"github.com/go-chi/chi/v5"
+	"github.com/nix-community/go-nix/pkg/narinfo"
+	"github.com/nix-community/go-nix/pkg/nixbase32"
+	"github.com/sirupsen/logrus"
+	log "github.com/sirupsen/logrus"
+)
+
+func registerNarinfoPut(s *Server) {
+	s.handler.Put("/{outputhash:^["+nixbase32.Alphabet+"]{32}}.narinfo", func(w http.ResponseWriter, r *http.Request) {
+		defer r.Body.Close()
+
+		ctx := r.Context()
+		log := log.WithField("outputhash", chi.URLParamFromCtx(ctx, "outputhash"))
+
+		// TODO: decide on merging behaviour.
+		// Maybe it's fine to add if contents are the same, but more sigs can be added?
+		// Right now, just replace a .narinfo for a path that already exists.
+
+		// read and parse the .narinfo file
+		narInfo, err := narinfo.Parse(r.Body)
+		if err != nil {
+			log.WithError(err).Error("unable to parse narinfo")
+			w.WriteHeader(http.StatusBadRequest)
+			_, err := w.Write([]byte("unable to parse narinfo"))
+			if err != nil {
+				log.WithError(err).Errorf("unable to write error message to client")
+			}
+
+			return
+		}
+
+		log = log.WithFields(logrus.Fields{
+			"narhash":     narInfo.NarHash.SRIString(),
+			"output_path": narInfo.StorePath,
+		})
+
+		// look up the narHash in our temporary map
+		s.narDbMu.Lock()
+		narData, found := s.narDb[narInfo.NarHash.SRIString()]
+		s.narDbMu.Unlock()
+		if !found {
+			log.Error("unable to find referred NAR")
+			w.WriteHeader(http.StatusBadRequest)
+			_, err := w.Write([]byte("unable to find referred NAR"))
+			if err != nil {
+				log.WithError(err).Errorf("unable to write error message to client")
+			}
+
+			return
+		}
+
+		rootNode := narData.rootNode
+
+		// compare fields with what we computed while receiving the NAR file
+
+		// NarSize needs to match
+		if narData.narSize != narInfo.NarSize {
+			log.Error("narsize mismatch")
+			w.WriteHeader(http.StatusBadRequest)
+			_, err := w.Write([]byte("unable to parse narinfo"))
+			if err != nil {
+				log.WithError(err).Errorf("unable to write error message to client")
+			}
+
+			return
+		}
+
+		pathInfo, err := importer.GenPathInfo(rootNode, narInfo)
+		if err != nil {
+			log.WithError(err).Error("unable to generate PathInfo")
+
+			w.WriteHeader(http.StatusInternalServerError)
+			_, err := w.Write([]byte("unable to generate PathInfo"))
+			if err != nil {
+				log.WithError(err).Errorf("unable to write error message to client")
+			}
+
+			return
+		}
+
+		log.WithField("pathInfo", pathInfo).Debug("inserted new pathInfo")
+
+		receivedPathInfo, err := s.pathInfoServiceClient.Put(ctx, pathInfo)
+		if err != nil {
+			log.WithError(err).Error("unable to upload pathinfo to service")
+			w.WriteHeader(http.StatusInternalServerError)
+			_, err := w.Write([]byte("unable to upload pathinfo to server"))
+			if err != nil {
+				log.WithError(err).Errorf("unable to write error message to client")
+			}
+
+			return
+		}
+
+		log.WithField("pathInfo", receivedPathInfo).Debug("got back PathInfo")
+	})
+}
diff --git a/tvix/nar-bridge-go/pkg/http/server.go b/tvix/nar-bridge-go/pkg/http/server.go
new file mode 100644
index 000000000000..fbcb20be18b7
--- /dev/null
+++ b/tvix/nar-bridge-go/pkg/http/server.go
@@ -0,0 +1,119 @@
+package http
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+
+	castorev1pb "code.tvl.fyi/tvix/castore-go"
+	storev1pb "code.tvl.fyi/tvix/store-go"
+	"github.com/go-chi/chi/middleware"
+	"github.com/go-chi/chi/v5"
+	log "github.com/sirupsen/logrus"
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
+)
+
+type Server struct {
+	srv     *http.Server
+	handler chi.Router
+
+	directoryServiceClient castorev1pb.DirectoryServiceClient
+	blobServiceClient      castorev1pb.BlobServiceClient
+	pathInfoServiceClient  storev1pb.PathInfoServiceClient
+
+	// When uploading NAR files to a HTTP binary cache, the .nar
+	// files are uploaded before the .narinfo files.
+	// We need *both* to be able to fully construct a PathInfo object.
+	// Keep a in-memory map of narhash(es) (in SRI) to (unnamed) root node and nar
+	// size.
+	// This is necessary until we can ask a PathInfoService for a node with a given
+	// narSha256.
+	narDbMu sync.Mutex
+	narDb   map[string]*narData
+}
+
+type narData struct {
+	rootNode *castorev1pb.Node
+	narSize  uint64
+}
+
+func New(
+	directoryServiceClient castorev1pb.DirectoryServiceClient,
+	blobServiceClient castorev1pb.BlobServiceClient,
+	pathInfoServiceClient storev1pb.PathInfoServiceClient,
+	enableAccessLog bool,
+	priority int,
+) *Server {
+	r := chi.NewRouter()
+	r.Use(func(h http.Handler) http.Handler {
+		return otelhttp.NewHandler(h, "http.request")
+	})
+
+	if enableAccessLog {
+		r.Use(middleware.Logger)
+	}
+
+	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
+		_, err := w.Write([]byte("nar-bridge"))
+		if err != nil {
+			log.Errorf("Unable to write response: %v", err)
+		}
+	})
+
+	r.Get("/nix-cache-info", func(w http.ResponseWriter, r *http.Request) {
+		_, err := w.Write([]byte(fmt.Sprintf("StoreDir: /nix/store\nWantMassQuery: 1\nPriority: %d\n", priority)))
+		if err != nil {
+			log.Errorf("Unable to write response: %v", err)
+		}
+	})
+
+	s := &Server{
+		handler:                r,
+		directoryServiceClient: directoryServiceClient,
+		blobServiceClient:      blobServiceClient,
+		pathInfoServiceClient:  pathInfoServiceClient,
+		narDb:                  make(map[string]*narData),
+	}
+
+	registerNarPut(s)
+	registerNarinfoPut(s)
+
+	registerNarinfoGet(s)
+	registerNarGet(s)
+
+	return s
+}
+
+func (s *Server) Shutdown(ctx context.Context) error {
+	return s.srv.Shutdown(ctx)
+}
+
+// ListenAndServer starts the webserver, and waits for it being closed or
+// shutdown, after which it'll return ErrServerClosed.
+func (s *Server) ListenAndServe(addr string) error {
+	s.srv = &http.Server{
+		Handler:      s.handler,
+		ReadTimeout:  500 * time.Second,
+		WriteTimeout: 500 * time.Second,
+		IdleTimeout:  500 * time.Second,
+	}
+
+	var listener net.Listener
+	var err error
+
+	// check addr. If it contains slashes, assume it's a unix domain socket.
+	if strings.Contains(addr, "/") {
+		listener, err = net.Listen("unix", addr)
+	} else {
+		listener, err = net.Listen("tcp", addr)
+	}
+	if err != nil {
+		return fmt.Errorf("unable to listen on %v: %w", addr, err)
+	}
+
+	return s.srv.Serve(listener)
+}
diff --git a/tvix/nar-bridge-go/pkg/http/util.go b/tvix/nar-bridge-go/pkg/http/util.go
new file mode 100644
index 000000000000..60febea1f430
--- /dev/null
+++ b/tvix/nar-bridge-go/pkg/http/util.go
@@ -0,0 +1,24 @@
+package http
+
+import (
+	"fmt"
+	nixhash "github.com/nix-community/go-nix/pkg/hash"
+)
+
+// parseNarHashFromUrl parses a nixbase32 string representing a sha256 NarHash
+// and returns a nixhash.Hash when it was able to parse, or an error.
+func parseNarHashFromUrl(narHashFromUrl string) (*nixhash.Hash, error) {
+	// peek at the length. If it's 52 characters, assume sha256,
+	// if it's something else, this is an error.
+	l := len(narHashFromUrl)
+	if l != 52 {
+		return nil, fmt.Errorf("invalid length of narHash: %v", l)
+	}
+
+	nixHash, err := nixhash.ParseNixBase32("sha256:" + narHashFromUrl)
+	if err != nil {
+		return nil, fmt.Errorf("unable to parse nixbase32 hash: %w", err)
+	}
+
+	return nixHash, nil
+}
generated by cgit-pink 1.4.1 (git 2.44.2) at 2024-09-07T12ยท10+0000