Milo: Add themed page for errors

milo/appengine/buildbot/master.go

 // Copyright 2016 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package buildbot
 
 import (
         "bytes"
         "compress/gzip"
         "encoding/json"
         "fmt"
         "sort"
         "time"
 
         ds "github.com/luci/gae/service/datastore"
         "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/milo/api/resp"
         "github.com/luci/luci-go/milo/appengine/settings"
+        "github.com/luci/luci-go/server/auth"
+        "github.com/luci/luci-go/server/auth/identity"
 
         "golang.org/x/net/context"
 )
 
 func decodeMasterEntry(
         c context.Context, entry *buildbotMasterEntry, master *buildbotMaster) error {
 
         reader, err := gzip.NewReader(bytes.NewReader(entry.Data))
         if err != nil {
                 return err
         }
         defer reader.Close()
         if err = json.NewDecoder(reader).Decode(master); err != nil {
                 return err
         }
         return nil
 }
 
+// User not logged in, master found, master public: nil
+// User not logged in, master not found: 401
+// User not logged in, master internal: 401
+// User logged in, master found, master internal: nil
+// User logged in, master not found: 404
+// User logged in, master found, master internal: 404
+// Other error: 500
+func checkAccess(c context.Context, err error, internal bool) error {
+        cu := auth.CurrentUser(c)
+        switch {
+        case err == ds.ErrNoSuchEntity:
+                if cu.Identity == identity.AnonymousIdentity {
+                        return errNotAuth
+                } else {
+                        return errMasterNotFound
+                }
+        case err != nil:
+                return err
+        }
+
+        // Do the ACL check if the entry is internal.
+        if internal {
+                allowed, err := settings.IsAllowedInternal(c)
+                if err != nil {
+                        return err
+                }
+                if !allowed {
+                        if cu.Identity == identity.AnonymousIdentity {
+                                return errNotAuth
+                        } else {
+                                return errMasterNotFound
+                        }
+                }
+        }
+
+        return nil
+}
+
 // getMasterEntry feches the named master and does an ACL check on the
 // current user.
+// It returns:
 func getMasterEntry(c context.Context, name string) (*buildbotMasterEntry, error) {
         entry := buildbotMasterEntry{Name: name}
         err := ds.Get(c, &entry)
-        switch {
-        case err == ds.ErrNoSuchEntity:
-                return nil, errMasterNotFound
-        case err != nil:
-                logging.WithError(err).Errorf(
-                        c, "Encountered error while fetching entry for %s:\n%s", name, err)
-                return nil, err
-        }
-
-        // Do the ACL check if the entry is internal.
-        if entry.Internal {
-                allowed, err := settings.IsAllowedInternal(c)
-                if err != nil {
-                        return nil, err
-                }
-                if !allowed {
-                        return nil, errMasterNotFound
-                }
-        }
-
-        return &entry, nil
+        err = checkAccess(c, err, entry.Internal)
+        return &entry, err
 }
 
 // getMasterJSON fetches the latest known buildbot master data and returns
 // the buildbotMaster struct (if found), whether or not it is internal,
 // the last modified time, and an error if not found.
 func getMasterJSON(c context.Context, name string) (
         master *buildbotMaster, t time.Time, err error) {
         master = &buildbotMaster{}
         entry, err := getMasterEntry(c, name)
         if err != nil {
@@ skipping 50 matching lines @@
                                 Label: bn,
                                 // Go templates escapes this for us, and also
                                 // slashes are not allowed in builder names.
                                 URL: fmt.Sprintf("/buildbot/%s/%s", entry.Name, bn),
                         })
                 }
                 result.Masters = append(result.Masters, ml)
         }
         return result, nil
 }