feat(gateway): redirect ipns b58mh peer id to cid

.github/workflows/gateway-sharness.yml

@@ -28,7 +28,7 @@ jobs:
         with:
           repository: ipfs/kubo
           path: kubo
-          ref: 503edee648e29c62888f05fa146ab13d9c65077d
+          ref: d17449d
       - name: Install Missing Tools
         run: sudo apt install -y socat net-tools fish libxml2-utils
       - name: Restore Go Cache

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"
@@ -325,6 +327,10 @@ func (i *handler) getOrHeadHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if handleIpnsB58mhToCidRedirection(w, r) {
+		return
+	}
+
 	contentPath := ipath.New(r.URL.Path)
 	ctx := context.WithValue(r.Context(), ContentPathKey, contentPath)
 	r = r.WithContext(ctx)
@@ -844,6 +850,45 @@ func handleServiceWorkerRegistration(r *http.Request) (err *ErrorResponse) {
 	return nil
 }
 
+// handleIpnsB58mhToCidRedirection redirects from /ipns/b58mh to /ipns/cid in
+// the most cost-effective way.
+func handleIpnsB58mhToCidRedirection(w http.ResponseWriter, r *http.Request) bool {
+	if w.Header().Get("Location") != "" {
+		// Ignore this if there is already a redirection in place. This happens
+		// if there is a subdomain redirection. In that case, the path is already
+		// converted to CIDv1.
+		return false
+	}
+
+	pathParts := strings.Split(r.URL.Path, "/")
+	if len(pathParts) < 3 {
+		return false
+	}
+
+	if pathParts[1] != "ipns" {
+		return false
+	}
+
+	s := pathParts[2]
+
+	// Similarly to peer.Decode, check the prefix first as it is  less computationally
+	// expensive. Base58 encoded peer IDs will start with a '1'.
+	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
+}
+
 // Attempt to fix redundant /ipfs/ namespace as long as resulting
 // 'intended' path is valid.  This is in case gremlins were tickled
 // wrong way and user ended up at /ipfs/ipfs/{cid} or /ipfs/ipns/{id}