Replaced old logic to check for valid path

Added the original logic to check for a invalid path and a simple test.

core/pathresolver.go

@@ -3,6 +3,7 @@ package core
 import (
 	"errors"
 	"strings"
+	"fmt"
 
 	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
 
@@ -29,8 +30,9 @@ func Resolve(ctx context.Context, n *IpfsNode, p path.Path) (*merkledag.Node, er
 		}
 
 		seg := p.Segments()
-		if len(seg) < 2 {
-			return nil, errors.New("No path given")
+
+		if len(seg) < 2 || seg[1] == "" { // just "/<protocol/>" without further segments
+			return nil, fmt.Errorf("invalid path: %s", string(p))
 		}
 
 		extensions := seg[2:]

core/pathresolver_test.go

+package core
+
+import (
+	"testing"
+
+	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
+	config "github.com/ipfs/go-ipfs/repo/config"
+	"github.com/ipfs/go-ipfs/util/testutil"
+	"github.com/ipfs/go-ipfs/repo"
+	path "github.com/ipfs/go-ipfs/path"
+)
+
+func TestResolveInvalidPath(t *testing.T) {
+	ctx := context.TODO()
+	id := testIdentity
+
+	r := &repo.Mock{
+		C: config.Config{
+			Identity: id,
+			Datastore: config.Datastore{
+				Type: "memory",
+			},
+			Addresses: config.Addresses{
+				Swarm: []string{"/ip4/0.0.0.0/tcp/4001"},
+				API:   "/ip4/127.0.0.1/tcp/8000",
+			},
+		},
+		D: testutil.ThreadSafeCloserMapDatastore(),
+	}
+
+	n, err := NewIPFSNode(ctx, Standard(r, false))
+	if n == nil || err != nil {
+		t.Error("Should have constructed.", err)
+	}
+
+	_, err = Resolve(ctx, n, path.Path("/ipfs/"))
+	if err == nil {
+		t.Error("Should get invalid path")
+	}
+
+}