swarm: give correct error on 0x hash prefix (ethereum#16195)

- added a case error struct that contains information about certain error cases
in which we would like to output more information to the client
- added a validation method that iterates and adds the information that is
stored in the error cases

.gitignore

@@ -34,6 +34,9 @@ profile.cov
 # IdeaIDE
 .idea
 
+# VS Code
+.vscode
+
 # dashboard
 /dashboard/assets/flow-typed
 /dashboard/assets/node_modules

swarm/api/http/error.go

@@ -35,6 +35,7 @@ import (
 
 //templateMap holds a mapping of an HTTP error code to a template
 var templateMap map[int]*template.Template
+var caseErrors []CaseError
 
 //metrics variables
 var (
@@ -51,6 +52,13 @@ type ErrorParams struct {
 	Details   template.HTML
 }
 
+//a custom error case struct that would be used to store validators and
+//additional error info to display with client responses.
+type CaseError struct {
+	Validator func(*Request) bool
+	Msg       func(*Request) string
+}
+
 //we init the error handling right on boot time, so lookup and http response is fast
 func init() {
 	initErrHandling()
@@ -74,6 +82,29 @@ func initErrHandling() {
 		//assign formatted HTML to the code
 		templateMap[code] = template.Must(template.New(fmt.Sprintf("%d", code)).Parse(tname))
 	}
+
+	caseErrors = []CaseError{
+		{
+			Validator: func(r *Request) bool { return r.uri != nil && r.uri.Addr != "" && strings.HasPrefix(r.uri.Addr, "0x") },
+			Msg: func(r *Request) string {
+				uriCopy := r.uri
+				uriCopy.Addr = strings.TrimPrefix(uriCopy.Addr, "0x")
+				return fmt.Sprintf(`The requested hash seems to be prefixed with '0x'. You will be redirected to the correct URL within 5 seconds.<br/>
+			Please click <a href='%[1]s'>here</a> if your browser does not redirect you.<script>setTimeout("location.href='%[1]s';",5000);</script>`, "/"+uriCopy.String())
+			},
+		}}
+}
+
+//ValidateCaseErrors is a method that process the request object through certain validators
+//that assert if certain conditions are met for further information to log as an error
+func ValidateCaseErrors(r *Request) string {
+	for _, err := range caseErrors {
+		if err.Validator(r) {
+			return err.Msg(r)
+		}
+	}
+
+	return ""
 }
 
 //ShowMultipeChoices is used when a user requests a resource in a manifest which results
@@ -82,10 +113,10 @@ func initErrHandling() {
 //For example, if the user requests bzz:/<hash>/read and that manifest contains entries
 //"readme.md" and "readinglist.txt", a HTML page is returned with this two links.
 //This only applies if the manifest has no default entry
-func ShowMultipleChoices(w http.ResponseWriter, r *http.Request, list api.ManifestList) {
+func ShowMultipleChoices(w http.ResponseWriter, r *Request, list api.ManifestList) {
 	msg := ""
 	if list.Entries == nil {
-		ShowError(w, r, "Internal Server Error", http.StatusInternalServerError)
+		ShowError(w, r, "Could not resolve", http.StatusInternalServerError)
 		return
 	}
 	//make links relative
@@ -102,7 +133,7 @@ func ShowMultipleChoices(w http.ResponseWriter, r *http.Request, list api.Manife
 		//create clickable link for each entry
 		msg += "<a href='" + base + e.Path + "'>" + e.Path + "</a><br/>"
 	}
-	respond(w, r, &ErrorParams{
+	respond(w, &r.Request, &ErrorParams{
 		Code:      http.StatusMultipleChoices,
 		Details:   template.HTML(msg),
 		Timestamp: time.Now().Format(time.RFC1123),
@@ -115,13 +146,15 @@ func ShowMultipleChoices(w http.ResponseWriter, r *http.Request, list api.Manife
 //The function just takes a string message which will be displayed in the error page.
 //The code is used to evaluate which template will be displayed
 //(and return the correct HTTP status code)
-func ShowError(w http.ResponseWriter, r *http.Request, msg string, code int) {
+func ShowError(w http.ResponseWriter, r *Request, msg string, code int) {
+	additionalMessage := ValidateCaseErrors(r)
 	if code == http.StatusInternalServerError {
 		log.Error(msg)
 	}
-	respond(w, r, &ErrorParams{
+	respond(w, &r.Request, &ErrorParams{
 		Code:      code,
 		Msg:       msg,
+		Details:   template.HTML(additionalMessage),
 		Timestamp: time.Now().Format(time.RFC1123),
 		template:  getTemplate(code),
 	})

swarm/api/http/error_templates.go

@@ -168,6 +168,11 @@ func GetGenericErrorPage() string {
                   {{.Msg}}
                 </td>
               </tr>
+              <tr>
+                <td class="value">
+                  {{.Details}}
+                </td>
+              </tr>
 
               <tr>
                 <td class="key">
@@ -342,6 +347,12 @@ func GetNotFoundErrorPage() string {
                   {{.Msg}}
                 </td>
               </tr>
+              <tr>
+                <td class="value">
+                  {{.Details}}
+                </td>
+              </tr>
+
 
               <tr>
                 <td class="key">

swarm/api/http/error_test.go

@@ -18,12 +18,13 @@ package http_test
 
 import (
 	"encoding/json"
-	"golang.org/x/net/html"
 	"io/ioutil"
 	"net/http"
 	"strings"
 	"testing"
 
+	"golang.org/x/net/html"
+
 	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
@@ -96,8 +97,37 @@ func Test500Page(t *testing.T) {
 	defer resp.Body.Close()
 	respbody, err = ioutil.ReadAll(resp.Body)
 
-	if resp.StatusCode != 500 || !strings.Contains(string(respbody), "500") {
-		t.Fatalf("Invalid Status Code received, expected 500, got %d", resp.StatusCode)
+	if resp.StatusCode != 404 {
+		t.Fatalf("Invalid Status Code received, expected 404, got %d", resp.StatusCode)
+	}
+
+	_, err = html.Parse(strings.NewReader(string(respbody)))
+	if err != nil {
+		t.Fatalf("HTML validation failed for error page returned!")
+	}
+}
+func Test500PageWith0xHashPrefix(t *testing.T) {
+	srv := testutil.NewTestSwarmServer(t)
+	defer srv.Close()
+
+	var resp *http.Response
+	var respbody []byte
+
+	url := srv.URL + "/bzz:/0xthisShouldFailWith500CodeAndAHelpfulMessage"
+	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 resp.StatusCode != 404 {
+		t.Fatalf("Invalid Status Code received, expected 404, got %d", resp.StatusCode)
+	}
+
+	if !strings.Contains(string(respbody), "The requested hash seems to be prefixed with") {
+		t.Fatalf("Did not receive the expected error message")
 	}
 
 	_, err = html.Parse(strings.NewReader(string(respbody)))
@@ -127,8 +157,8 @@ func TestJsonResponse(t *testing.T) {
 	defer resp.Body.Close()
 	respbody, err = ioutil.ReadAll(resp.Body)
 
-	if resp.StatusCode != 500 {
-		t.Fatalf("Invalid Status Code received, expected 500, got %d", resp.StatusCode)
+	if resp.StatusCode != 404 {
+		t.Fatalf("Invalid Status Code received, expected 404, got %d", resp.StatusCode)
 	}
 
 	if !isJSON(string(respbody)) {

swarm/api/http/server.go

@@ -336,7 +336,7 @@ func (s *Server) HandleGet(w http.ResponseWriter, r *Request) {
 	key, err := s.api.Resolve(r.uri)
 	if err != nil {
 		getFail.Inc(1)
-		s.Error(w, r, fmt.Errorf("error resolving %s: %s", r.uri.Addr, err))
+		s.NotFound(w, r, fmt.Errorf("error resolving %s: %s", r.uri.Addr, err))
 		return
 	}
 
@@ -421,7 +421,7 @@ func (s *Server) HandleGetFiles(w http.ResponseWriter, r *Request) {
 	key, err := s.api.Resolve(r.uri)
 	if err != nil {
 		getFilesFail.Inc(1)
-		s.Error(w, r, fmt.Errorf("error resolving %s: %s", r.uri.Addr, err))
+		s.NotFound(w, r, fmt.Errorf("error resolving %s: %s", r.uri.Addr, err))
 		return
 	}
 
@@ -494,7 +494,7 @@ func (s *Server) HandleGetList(w http.ResponseWriter, r *Request) {
 	key, err := s.api.Resolve(r.uri)
 	if err != nil {
 		getListFail.Inc(1)
-		s.Error(w, r, fmt.Errorf("error resolving %s: %s", r.uri.Addr, err))
+		s.NotFound(w, r, fmt.Errorf("error resolving %s: %s", r.uri.Addr, err))
 		return
 	}
 
@@ -598,7 +598,7 @@ func (s *Server) HandleGetFile(w http.ResponseWriter, r *Request) {
 	key, err := s.api.Resolve(r.uri)
 	if err != nil {
 		getFileFail.Inc(1)
-		s.Error(w, r, fmt.Errorf("error resolving %s: %s", r.uri.Addr, err))
+		s.NotFound(w, r, fmt.Errorf("error resolving %s: %s", r.uri.Addr, err))
 		return
 	}
 
@@ -628,7 +628,7 @@ func (s *Server) HandleGetFile(w http.ResponseWriter, r *Request) {
 
 		s.logDebug(fmt.Sprintf("Multiple choices! -->  %v", list))
 		//show a nice page links to available entries
-		ShowMultipleChoices(w, &r.Request, list)
+		ShowMultipleChoices(w, r, list)
 		return
 	}
 
@@ -693,15 +693,15 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		//   strictly a traditional PUT request which replaces content
 		//   at a URI, and POST is more ubiquitous)
 		if uri.Raw() || uri.DeprecatedRaw() {
-			ShowError(w, r, fmt.Sprintf("No PUT to %s allowed.", uri), http.StatusBadRequest)
+			ShowError(w, req, fmt.Sprintf("No PUT to %s allowed.", uri), http.StatusBadRequest)
 			return
 		} else {
 			s.HandlePostFiles(w, req)
 		}
 
 	case "DELETE":
 		if uri.Raw() || uri.DeprecatedRaw() {
-			ShowError(w, r, fmt.Sprintf("No DELETE to %s allowed.", uri), http.StatusBadRequest)
+			ShowError(w, req, fmt.Sprintf("No DELETE to %s allowed.", uri), http.StatusBadRequest)
 			return
 		}
 		s.HandleDelete(w, req)
@@ -725,7 +725,7 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		s.HandleGetFile(w, req)
 
 	default:
-		ShowError(w, r, fmt.Sprintf("Method "+r.Method+" is not supported.", uri), http.StatusMethodNotAllowed)
+		ShowError(w, req, fmt.Sprintf("Method "+r.Method+" is not supported.", uri), http.StatusMethodNotAllowed)
 
 	}
 }
@@ -757,13 +757,13 @@ func (s *Server) logError(format string, v ...interface{}) {
 }
 
 func (s *Server) BadRequest(w http.ResponseWriter, r *Request, reason string) {
-	ShowError(w, &r.Request, fmt.Sprintf("Bad request %s %s: %s", r.Method, r.uri, reason), http.StatusBadRequest)
+	ShowError(w, r, fmt.Sprintf("Bad request %s %s: %s", r.Request.Method, r.uri, reason), http.StatusBadRequest)
 }
 
 func (s *Server) Error(w http.ResponseWriter, r *Request, err error) {
-	ShowError(w, &r.Request, fmt.Sprintf("Error serving %s %s: %s", r.Method, r.uri, err), http.StatusInternalServerError)
+	ShowError(w, r, fmt.Sprintf("Error serving %s %s: %s", r.Request.Method, r.uri, err), http.StatusInternalServerError)
 }
 
 func (s *Server) NotFound(w http.ResponseWriter, r *Request, err error) {
-	ShowError(w, &r.Request, fmt.Sprintf("NOT FOUND error serving %s %s: %s", r.Method, r.uri, err), http.StatusNotFound)
+	ShowError(w, r, fmt.Sprintf("NOT FOUND error serving %s %s: %s", r.Request.Method, r.uri, err), http.StatusNotFound)
 }