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9bd346e250
This ensures that child contexts are passed around between the handlers so that traces show the call hierarchy correctly.
93 lines
3.3 KiB
Go
93 lines
3.3 KiB
Go
package corehttp
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import (
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"context"
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"fmt"
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"net/http"
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"time"
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blocks "github.com/ipfs/go-block-format"
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cid "github.com/ipfs/go-cid"
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"github.com/ipfs/go-ipfs/tracing"
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coreiface "github.com/ipfs/interface-go-ipfs-core"
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ipath "github.com/ipfs/interface-go-ipfs-core/path"
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gocar "github.com/ipld/go-car"
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selectorparse "github.com/ipld/go-ipld-prime/traversal/selector/parse"
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"go.opentelemetry.io/otel/attribute"
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"go.opentelemetry.io/otel/trace"
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)
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// serveCAR returns a CAR stream for specific DAG+selector
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func (i *gatewayHandler) serveCAR(ctx context.Context, w http.ResponseWriter, r *http.Request, resolvedPath ipath.Resolved, contentPath ipath.Path, carVersion string, begin time.Time) {
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ctx, span := tracing.Span(ctx, "Gateway", "ServeCAR", trace.WithAttributes(attribute.String("path", resolvedPath.String())))
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defer span.End()
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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switch carVersion {
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case "": // noop, client does not care about version
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case "1": // noop, we support this
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default:
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err := fmt.Errorf("only version=1 is supported")
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webError(w, "unsupported CAR version", err, http.StatusBadRequest)
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return
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}
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rootCid := resolvedPath.Cid()
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// Set Content-Disposition
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name := rootCid.String() + ".car"
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setContentDispositionHeader(w, name, "attachment")
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// Weak Etag W/ because we can't guarantee byte-for-byte identical responses
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// (CAR is streamed, and in theory, blocks may arrive from datastore in non-deterministic order)
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etag := `W/` + getEtag(r, rootCid)
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w.Header().Set("Etag", etag)
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// Finish early if Etag match
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if r.Header.Get("If-None-Match") == etag {
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w.WriteHeader(http.StatusNotModified)
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return
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}
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// Make it clear we don't support range-requests over a car stream
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// Partial downloads and resumes should be handled using
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// IPLD selectors: https://github.com/ipfs/go-ipfs/issues/8769
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w.Header().Set("Accept-Ranges", "none")
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// Explicit Cache-Control to ensure fresh stream on retry.
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// CAR stream could be interrupted, and client should be able to resume and get full response, not the truncated one
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w.Header().Set("Cache-Control", "no-cache, no-transform")
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w.Header().Set("Content-Type", "application/vnd.ipld.car; version=1")
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w.Header().Set("X-Content-Type-Options", "nosniff") // no funny business in the browsers :^)
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// Same go-car settings as dag.export command
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store := dagStore{dag: i.api.Dag(), ctx: ctx}
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// TODO: support selectors passed as request param: https://github.com/ipfs/go-ipfs/issues/8769
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dag := gocar.Dag{Root: rootCid, Selector: selectorparse.CommonSelector_ExploreAllRecursively}
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car := gocar.NewSelectiveCar(ctx, store, []gocar.Dag{dag}, gocar.TraverseLinksOnlyOnce())
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if err := car.Write(w); err != nil {
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// We return error as a trailer, however it is not something browsers can access
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// (https://github.com/mdn/browser-compat-data/issues/14703)
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// Due to this, we suggest client always verify that
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// the received CAR stream response is matching requested DAG selector
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w.Header().Set("X-Stream-Error", err.Error())
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return
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}
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// Update metrics
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i.carStreamGetMetric.WithLabelValues(contentPath.Namespace()).Observe(time.Since(begin).Seconds())
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}
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type dagStore struct {
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dag coreiface.APIDagService
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ctx context.Context
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}
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func (ds dagStore) Get(c cid.Cid) (blocks.Block, error) {
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obj, err := ds.dag.Get(ds.ctx, c)
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return obj, err
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}
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