swarm/api: url scheme bzz-hash to get hashes of swarm content (#15238) (#15715)

* swarm/api: url scheme bzz-hash to get hashes of swarm content (#15238)

Update URI to support bzz-hash scheme and handle such HTTP requests by
responding with hash of the content as a text/plain response.

* swarm/api: return hash of the content for bzz-hash:// requests

* swarm/api: revert "return hash of the content for bzz-hash:// requests"

Return hashes of the content that would be returned by bzz-raw
request.

* swarm/api/http: handle error in TestBzzGetPath

* swarm/api: remove extra blank line in comment

2 files changed, 58 insertions, 14 deletions

diff --git a/swarm/api/http/server.go b/swarm/api/http/server.go
index 3872cbc4f..74341899d 100644
--- a/swarm/api/http/server.go
+++ b/swarm/api/http/server.go
@@ -290,9 +290,12 @@ func (s *Server) HandleDelete(w http.ResponseWriter, r *Request) {
 	fmt.Fprint(w, newKey)
 }
 
-// HandleGetRaw handles a GET request to bzz-raw://<key> and responds with
-// the raw content stored at the given storage key
-func (s *Server) HandleGetRaw(w http.ResponseWriter, r *Request) {
+// HandleGet handles a GET request to
+// - bzz-raw://<key> and responds with the raw content stored at the
+//   given storage key
+// - bzz-hash://<key> and responds with the hash of the content stored
+//   at the given storage key as a text/plain response
+func (s *Server) HandleGet(w http.ResponseWriter, r *Request) {
 	key, err := s.api.Resolve(r.uri)
 	if err != nil {
 		s.Error(w, r, fmt.Errorf("error resolving %s: %s", r.uri.Addr, err))
@@ -345,15 +348,22 @@ func (s *Server) HandleGetRaw(w http.ResponseWriter, r *Request) {
 		return
 	}
 
-	// allow the request to overwrite the content type using a query
-	// parameter
-	contentType := "application/octet-stream"
-	if typ := r.URL.Query().Get("content_type"); typ != "" {
-		contentType = typ
-	}
-	w.Header().Set("Content-Type", contentType)
+	switch {
+	case r.uri.Raw():
+		// allow the request to overwrite the content type using a query
+		// parameter
+		contentType := "application/octet-stream"
+		if typ := r.URL.Query().Get("content_type"); typ != "" {
+			contentType = typ
+		}
+		w.Header().Set("Content-Type", contentType)
 
-	http.ServeContent(w, &r.Request, "", time.Now(), reader)
+		http.ServeContent(w, &r.Request, "", time.Now(), reader)
+	case r.uri.Hash():
+		w.Header().Set("Content-Type", "text/plain")
+		w.WriteHeader(http.StatusOK)
+		fmt.Fprint(w, key)
+	}
 }
 
 // HandleGetFiles handles a GET request to bzz:/<manifest> with an Accept
@@ -619,8 +629,8 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		s.HandleDelete(w, req)
 
 	case "GET":
-		if uri.Raw() || uri.DeprecatedRaw() {
-			s.HandleGetRaw(w, req)
+		if uri.Raw() || uri.Hash() || uri.DeprecatedRaw() {
+			s.HandleGet(w, req)
 			return
 		}
 
diff --git a/swarm/api/http/server_test.go b/swarm/api/http/server_test.go
index dbbfa3b07..305d5cf7d 100644
--- a/swarm/api/http/server_test.go
+++ b/swarm/api/http/server_test.go
@@ -33,7 +33,7 @@ import (
 	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
-func TestBzzrGetPath(t *testing.T) {
+func TestBzzGetPath(t *testing.T) {
 
 	var err error
 
@@ -104,6 +104,38 @@ func TestBzzrGetPath(t *testing.T) {
 		}
 	}
 
+	for k, v := range testrequests {
+		var resp *http.Response
+		var respbody []byte
+
+		url := srv.URL + "/bzz-hash:/"
+		if k[:] != "" {
+			url += common.ToHex(key[0])[2:] + "/" + k[1:]
+		}
+		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 err != nil {
+			t.Fatalf("Read request body: %v", err)
+		}
+
+		if string(respbody) != key[v].String() {
+			isexpectedfailrequest := false
+
+			for _, r := range expectedfailrequests {
+				if k[:] == r {
+					isexpectedfailrequest = true
+				}
+			}
+			if !isexpectedfailrequest {
+				t.Fatalf("Response body does not match, expected: %v, got %v", key[v], string(respbody))
+			}
+		}
+	}
+
 	for _, c := range []struct {
 		path string
 		json string
@@ -197,6 +229,7 @@ func TestBzzrGetPath(t *testing.T) {
 		srv.URL + "/bzz-immutable:/nonhash",
 		srv.URL + "/bzz-raw:/nonhash",
 		srv.URL + "/bzz-list:/nonhash",
+		srv.URL + "/bzz-hash:/nonhash",
 	}
 
 	nonhashresponses := []string{
@@ -204,6 +237,7 @@ func TestBzzrGetPath(t *testing.T) {
 		"error resolving nonhash: immutable address not a content hash: &#34;nonhash&#34;",
 		"error resolving nonhash: no DNS to resolve name: &#34;nonhash&#34;",
 		"error resolving nonhash: no DNS to resolve name: &#34;nonhash&#34;",
+		"error resolving nonhash: no DNS to resolve name: &#34;nonhash&#34;",
 	}
 
 	for i, url := range nonhashtests {