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handler_tar.go
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/
handler_tar.go
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package gateway
import (
"context"
"fmt"
"net/http"
"time"
"github.com/ipfs/boxo/files"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/trace"
)
var unixEpochTime = time.Unix(0, 0)
func (i *handler) serveTAR(ctx context.Context, w http.ResponseWriter, r *http.Request, rq *requestData) bool {
ctx, span := spanTrace(ctx, "Handler.ServeTAR", trace.WithAttributes(attribute.String("path", rq.immutablePath.String())))
defer span.End()
ctx, cancel := context.WithCancel(ctx)
defer cancel()
// Get Unixfs file (or directory)
pathMetadata, file, err := i.backend.GetAll(ctx, rq.mostlyResolvedPath())
if !i.handleRequestErrors(w, r, rq.contentPath, err) {
return false
}
defer file.Close()
setIpfsRootsHeader(w, rq, &pathMetadata)
rootCid := pathMetadata.LastSegment.RootCid()
// Set Cache-Control and read optional Last-Modified time
modtime := addCacheControlHeaders(w, r, rq.contentPath, rq.ttl, rq.lastMod, rootCid, tarResponseFormat)
// Set Content-Disposition
var name string
if urlFilename := r.URL.Query().Get("filename"); urlFilename != "" {
name = urlFilename
} else {
name = rootCid.String() + ".tar"
}
setContentDispositionHeader(w, name, "attachment")
// Construct the TAR writer
tarw, err := files.NewTarWriter(w)
if err != nil {
i.webError(w, r, fmt.Errorf("could not build tar writer: %w", err), http.StatusInternalServerError)
return false
}
defer tarw.Close()
// Sets correct Last-Modified header. This code is borrowed from the standard
// library (net/http/server.go) as we cannot use serveFile without throwing the entire
// TAR into the memory first.
if !(modtime.IsZero() || modtime.Equal(unixEpochTime)) {
w.Header().Set("Last-Modified", modtime.UTC().Format(http.TimeFormat))
}
w.Header().Set("Content-Type", tarResponseFormat)
w.Header().Set("X-Content-Type-Options", "nosniff") // no funny business in the browsers :^)
// The TAR has a top-level directory (or file) named by the CID.
if err := tarw.WriteFile(file, rootCid.String()); err != nil {
// Update fail metric
i.tarStreamFailMetric.WithLabelValues(rq.contentPath.Namespace()).Observe(time.Since(rq.begin).Seconds())
w.Header().Set("X-Stream-Error", err.Error())
// Trailer headers do not work in web browsers
// (see https://github.com/mdn/browser-compat-data/issues/14703)
// and we have limited options around error handling in browser contexts.
// To improve UX/DX, we finish response stream with error message, allowing client to
// (1) detect error by having corrupted TAR
// (2) be able to reason what went wrong by instecting the tail of TAR stream
_, _ = w.Write([]byte(err.Error()))
return false
}
// Update metrics
i.tarStreamGetMetric.WithLabelValues(rq.contentPath.Namespace()).Observe(time.Since(rq.begin).Seconds())
return true
}