swarm/api: better name resolver handling (#3754)

Fixes #3608

cmd/swarm/main.go

@@ -358,6 +358,8 @@ func registerBzzService(ctx *cli.Context, stack *node.Node) {
 			if err != nil {
 				utils.Fatalf("Can't connect: %v", err)
 			}
+		} else {
+			swapEnabled = false
 		}
 		return swarm.NewSwarm(ctx, client, bzzconfig, swapEnabled, syncEnabled, cors)
 	}

swarm/api/api.go

@@ -17,7 +17,6 @@
 package api
 
 import (
-	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -84,25 +83,28 @@ type ErrResolve error
 // DNS Resolver
 func (self *Api) Resolve(uri *URI) (storage.Key, error) {
 	log.Trace(fmt.Sprintf("Resolving : %v", uri.Addr))
-	if hashMatcher.MatchString(uri.Addr) {
-		log.Trace(fmt.Sprintf("addr is a hash: %q", uri.Addr))
-		return storage.Key(common.Hex2Bytes(uri.Addr)), nil
+
+	var err error
+	if !uri.Immutable() {
+		if self.dns != nil {
+			resolved, err := self.dns.Resolve(uri.Addr)
+			if err == nil {
+				return resolved[:], nil
+			}
+		} else {
+			err = fmt.Errorf("no DNS to resolve name")
 		}
-	if uri.Immutable() {
-		return nil, errors.New("refusing to resolve immutable address")
 	}
-	if self.dns == nil {
-		return nil, fmt.Errorf("unable to resolve addr %q, resolver not configured", uri.Addr)
+	if hashMatcher.MatchString(uri.Addr) {
+		return storage.Key(common.Hex2Bytes(uri.Addr)), nil
 	}
-	hash, err := self.dns.Resolve(uri.Addr)
 	if err != nil {
-		log.Warn(fmt.Sprintf("DNS error resolving addr %q: %s", uri.Addr, err))
-		return nil, ErrResolve(err)
+		return nil, fmt.Errorf("'%s' does not resolve: %v but is not a content hash", uri.Addr, err)
 	}
-	log.Trace(fmt.Sprintf("addr lookup: %v -> %v", uri.Addr, hash))
-	return hash[:], nil
+	return nil, fmt.Errorf("'%s' is not a content hash", uri.Addr)
 }
 
+
 // Put provides singleton manifest creation on top of dpa store
 func (self *Api) Put(content, contentType string) (storage.Key, error) {
 	r := strings.NewReader(content)

swarm/api/http/server_test.go

@@ -99,4 +99,32 @@ func TestBzzrGetPath(t *testing.T) {
 		}
 	}
 
+	nonhashtests := []string{
+		srv.URL + "/bzz:/name",
+		srv.URL + "/bzzi:/nonhash",
+		srv.URL + "/bzzr:/nonhash",
+	}
+
+	nonhashresponses := []string{
+		"error resolving name: 'name' does not resolve: no DNS to resolve name but is not a content hash\n",
+		"error resolving nonhash: 'nonhash' is not a content hash\n",
+		"error resolving nonhash: 'nonhash' does not resolve: no DNS to resolve name but is not a content hash\n",
+	}
+
+	for i, url := range nonhashtests {
+		var resp *http.Response
+		var respbody []byte
+
+		resp, err = http.Get(url)
+
+		if err != nil {
+			t.Fatalf("Request failed: %v", err)
+		}
+		defer resp.Body.Close()
+		respbody, err = ioutil.ReadAll(resp.Body)
+		if string(respbody) != nonhashresponses[i] {
+			t.Fatalf("Non-Hash response body does not match, expected: %v, got: %v", nonhashresponses[i], string(respbody))
+		}
+	}
+
 }

swarm/swarm.go

@@ -27,6 +27,7 @@ import (
 	"github.com/ethereum/go-ethereum/contracts/chequebook"
 	"github.com/ethereum/go-ethereum/contracts/ens"
 	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/node"
 	"github.com/ethereum/go-ethereum/p2p"
@@ -134,10 +135,14 @@ func NewSwarm(ctx *node.ServiceContext, backend chequebook.Backend, config *api.
 	// set up high level api
 	transactOpts := bind.NewKeyedTransactor(self.privateKey)
 
+	if backend == (*ethclient.Client)(nil) {
+		log.Warn("No ENS, please specify non-empty --ethapi to use domain name resolution")
+	} else {
 		self.dns, err = ens.NewENS(transactOpts, config.EnsRoot, self.backend)
 		if err != nil {
 			return nil, err
 		}
+	}
 	log.Debug(fmt.Sprintf("-> Swarm Domain Name Registrar @ address %v", config.EnsRoot.Hex()))
 
 	self.api = api.NewApi(self.dpa, self.dns)