feat(gateway): redirect ipns b58mh to cid

gateway/gateway_test.go

@@ -548,3 +548,15 @@ func TestGoGetSupport(t *testing.T) {
 	assert.Nil(t, err)
 	assert.Equal(t, http.StatusOK, res.StatusCode)
 }
+
+func TestIpnsBase58MultihashRedirect(t *testing.T) {
+	ts, _, _ := newTestServerAndNode(t, nil)
+	t.Logf("test server url: %s", ts.URL)
+
+	req, err := http.NewRequest(http.MethodGet, ts.URL+"/ipns/12D3KooWRBy97UB99e3J6hiPesre1MZeuNQvfan4gBziswrRJsNK?keep=query", nil)
+	assert.Nil(t, err)
+
+	res, err := doWithoutRedirect(req)
+	assert.Nil(t, err)
+	assert.Equal(t, "/ipns/bafzaajaiaejcbzdibmxyzdjbbehgvizh6g5tikvy47mshdy6gwbruvgwvd24seje?keep=query", res.Header.Get("Location"))
+}

gateway/handler.go

@@ -19,6 +19,8 @@ import (
 	ipath "github.com/ipfs/boxo/coreiface/path"
 	cid "github.com/ipfs/go-cid"
 	logging "github.com/ipfs/go-log"
+	"github.com/libp2p/go-libp2p/core/peer"
+	"github.com/multiformats/go-multihash"
 	prometheus "github.com/prometheus/client_golang/prometheus"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
@@ -305,6 +307,34 @@ func (i *handler) optionsHandler(w http.ResponseWriter, r *http.Request) {
 	i.addUserHeaders(w) // return all custom headers (including CORS ones, if set)
 }
 
+// handleIpnsPeerIdToCidRedirection redirects from /ipns/b58mh to /ipns/cid in
+// the most cost-effective way.
+func handleIpnsPeerIdToCidRedirection(w http.ResponseWriter, r *http.Request) bool {
+	pathParts := strings.Split(r.URL.Path, "/")
+	if len(pathParts) < 3 {
+		return false
+	}
+
+	s := pathParts[2]
+
+	// Similarly to peer.Decode, check the prefix first as it is
+	// less computationally expensive.
+	if !strings.HasPrefix(s, "1") {
+		return false
+	}
+
+	// Decode the base58 encoded sha256 or identity multihash.
+	m, err := multihash.FromB58String(s)
+	if err != nil {
+		return false
+	}
+
+	pathParts[2] = peer.ToCid(peer.ID(m)).String()
+	r.URL.Path = strings.Join(pathParts, "/")
+	http.Redirect(w, r, r.URL.String(), http.StatusFound)
+	return true
+}
+
 func (i *handler) getOrHeadHandler(w http.ResponseWriter, r *http.Request) {
 	begin := time.Now()
 
@@ -325,6 +355,10 @@ func (i *handler) getOrHeadHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if handleIpnsPeerIdToCidRedirection(w, r) {
+		return
+	}
+
 	contentPath := ipath.New(r.URL.Path)
 	ctx := context.WithValue(r.Context(), ContentPathKey, contentPath)
 	r = r.WithContext(ctx)