namesys: Make paths with multiple segemnts work. Fixes #2059

 Also fixes non-recursive resolve erring instead showing one step.

 The patch of core/commands/resolve.go could be done better but I don't
 know how to get access to ErrResolveRecursion.

 It allows for dnslinks into sub-segments. So for example hosting
 multiple blogs
 on just domains from one pubkey.

 Fixes #2059

 Add tests and fix case when dnslinks references dnslink

License: MIT
Signed-off-by: Jakub (Kubuxu) Sztandera <kubuxu@gmail.com>

namesys/dns.go

@@ -45,12 +45,14 @@ func (r *DNSResolver) ResolveN(ctx context.Context, name string, depth int) (pat
 // TXT records for a given domain name should contain a b58
 // encoded multihash.
 func (r *DNSResolver) resolveOnce(ctx context.Context, name string) (path.Path, error) {
-	if !isd.IsDomain(name) {
+	segments := strings.SplitN(name, "/", 2)
+
+	if !isd.IsDomain(segments[0]) {
 		return "", errors.New("not a valid domain name")
 	}
 
-	log.Infof("DNSResolver resolving %s", name)
-	txt, err := r.lookupTXT(name)
+	log.Infof("DNSResolver resolving %s", segments[0])
+	txt, err := r.lookupTXT(segments[0])
 	if err != nil {
 		return "", err
 	}
@@ -58,6 +60,9 @@ func (r *DNSResolver) resolveOnce(ctx context.Context, name string) (path.Path,
 	for _, t := range txt {
 		p, err := parseEntry(t)
 		if err == nil {
+			if len(segments) > 1 {
+				return path.FromSegments(p.String() + "/", segments[1])
+			}
 			return p, nil
 		}
 	}

namesys/dns_test.go

@@ -18,6 +18,7 @@ func (m *mockDNS) lookupTXT(name string) (txt []string, err error) {
 }
 
 func TestDnsEntryParsing(t *testing.T) {
+
 	goodEntries := []string{
 		"QmY3hE8xgFCjGcz6PHgnvJz5HZi1BaKRfPkn1ghZUcYMjD",
 		"dnslink=/ipfs/QmY3hE8xgFCjGcz6PHgnvJz5HZi1BaKRfPkn1ghZUcYMjD",
@@ -86,6 +87,12 @@ func newMockDNS() *mockDNS {
 			"bad.example.com": []string{
 				"dnslink=",
 			},
+			"withsegment.example.com": []string{
+				"dnslink=/ipfs/QmY3hE8xgFCjGcz6PHgnvJz5HZi1BaKRfPkn1ghZUcYMjD/sub/segment",
+			},
+			"withrecsegment.example.com": []string{
+				"dnslink=/ipns/withsegment.example.com/subsub",
+			},
 		},
 	}
 }
@@ -109,4 +116,6 @@ func TestDNSResolution(t *testing.T) {
 	testResolution(t, r, "loop1.example.com", 3, "/ipns/loop2.example.com", ErrResolveRecursion)
 	testResolution(t, r, "loop1.example.com", DefaultDepthLimit, "/ipns/loop1.example.com", ErrResolveRecursion)
 	testResolution(t, r, "bad.example.com", DefaultDepthLimit, "", ErrResolveFailed)
+	testResolution(t, r, "withsegment.example.com", DefaultDepthLimit, "/ipfs/QmY3hE8xgFCjGcz6PHgnvJz5HZi1BaKRfPkn1ghZUcYMjD/sub/segment", nil)
+	testResolution(t, r, "withrecsegment.example.com", DefaultDepthLimit, "/ipfs/QmY3hE8xgFCjGcz6PHgnvJz5HZi1BaKRfPkn1ghZUcYMjD/sub/segment/subsub", nil)
 }

namesys/namesys.go

@@ -64,17 +64,21 @@ func (ns *mpns) resolveOnce(ctx context.Context, name string) (path.Path, error)
 	if !strings.HasPrefix(name, "/ipns/") {
 		name = "/ipns/" + name
 	}
-	segments := strings.SplitN(name, "/", 3)
+	segments := strings.SplitN(name, "/", 4)
 	if len(segments) < 3 || segments[0] != "" {
 		log.Warningf("Invalid name syntax for %s", name)
 		return "", ErrResolveFailed
 	}
 
 	for protocol, resolver := range ns.resolvers {
-		log.Debugf("Attempting to resolve %s with %s", name, protocol)
+		log.Debugf("Attempting to resolve %s with %s", segments[2], protocol)
 		p, err := resolver.resolveOnce(ctx, segments[2])
 		if err == nil {
-			return p, err
+			if len(segments) > 3 {
+				return path.FromSegments(p.String() + "/", segments[3])
+			} else {
+				return p, err
+			}
 		}
 	}
 	log.Warningf("No resolver found for %s", name)

namesys/routing.go

@@ -123,7 +123,7 @@ func (r *routingResolver) resolveOnce(ctx context.Context, name string) (path.Pa
 
 	hash, err := mh.FromB58String(name)
 	if err != nil {
-		log.Warning("RoutingResolve: bad input hash: [%s]\n", name)
+		log.Warningf("RoutingResolve: bad input hash: [%s]\n", name)
 		return "", err
 	}
 	// name should be a multihash. if it isn't, error out here.