From b0771a98d1af7f61634b1cd5f1ea55802630471f Mon Sep 17 00:00:00 2001
From: Henrique Dias <hacdias@gmail.com>
Date: Wed, 8 Feb 2023 09:53:40 +0100
Subject: [PATCH] fix: example get ipns record with routing api

---
 examples/gateway/common/blocks.go | 20 +++++++++++++++++---
 examples/go.mod                   |  2 +-
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/examples/gateway/common/blocks.go b/examples/gateway/common/blocks.go
index a34acae01d..a0a0f47025 100644
--- a/examples/gateway/common/blocks.go
+++ b/examples/gateway/common/blocks.go
@@ -31,7 +31,9 @@ import (
 	"github.com/ipld/go-ipld-prime"
 	"github.com/ipld/go-ipld-prime/node/basicnode"
 	"github.com/ipld/go-ipld-prime/schema"
+	"github.com/libp2p/go-libp2p/core/peer"
 	"github.com/libp2p/go-libp2p/core/routing"
+	mc "github.com/multiformats/go-multicodec"
 )
 
 func NewBlocksHandler(gw *BlocksGateway, port int) http.Handler {
@@ -138,11 +140,23 @@ func (api *BlocksGateway) GetBlock(ctx context.Context, c cid.Cid) (blocks.Block
 }
 
 func (api *BlocksGateway) GetIPNSRecord(ctx context.Context, c cid.Cid) ([]byte, error) {
-	if api.routing != nil {
-		return api.routing.GetValue(ctx, "/ipns/"+c.String())
+	if api.routing == nil {
+		return nil, routing.ErrNotSupported
 	}
 
-	return nil, routing.ErrNotSupported
+	// Fails fast if the CID is not an encoded Libp2p Key, avoids wasteful
+	// round trips to the remote routing provider.
+	if mc.Code(c.Type()) != mc.Libp2pKey {
+		return nil, errors.New("provided cid is not an encoded libp2p key")
+	}
+
+	// The value store expects the key itself to be encoded as a multihash.
+	id, err := peer.FromCid(c)
+	if err != nil {
+		return nil, err
+	}
+
+	return api.routing.GetValue(ctx, "/ipns/"+string(id))
 }
 
 func (api *BlocksGateway) GetDNSLinkRecord(ctx context.Context, hostname string) (ifacepath.Path, error) {
diff --git a/examples/go.mod b/examples/go.mod
index b6d0b1372a..59b57d4477 100644
--- a/examples/go.mod
+++ b/examples/go.mod
@@ -22,6 +22,7 @@ require (
 	github.com/ipld/go-codec-dagpb v1.5.0
 	github.com/ipld/go-ipld-prime v0.19.0
 	github.com/libp2p/go-libp2p v0.24.2
+	github.com/multiformats/go-multicodec v0.7.0
 	github.com/prometheus/client_golang v1.14.0
 	github.com/stretchr/testify v1.8.1
 )
@@ -82,7 +83,6 @@ require (
 	github.com/multiformats/go-multiaddr v0.8.0 // indirect
 	github.com/multiformats/go-multiaddr-dns v0.3.1 // indirect
 	github.com/multiformats/go-multibase v0.1.1 // indirect
-	github.com/multiformats/go-multicodec v0.7.0 // indirect
 	github.com/multiformats/go-multihash v0.2.1 // indirect
 	github.com/multiformats/go-varint v0.0.7 // indirect
 	github.com/opentracing/opentracing-go v1.2.0 // indirect