Initial distributor implementation

common/api/dm/service/v1/quest_desc_normalize.go

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package dm
+
+import (
+        "crypto/sha256"
+        "encoding/base64"
+        "fmt"
+
+        "github.com/golang/protobuf/proto"
+        "github.com/luci/luci-go/common/api/template"
+)
+
+// IsEmpty returns true if this metadata retry message only contains
+// zero-values.
+func (q *Quest_Desc_Meta_Retry) IsEmpty() bool {
+        return q.Crashed == 0 && q.Expired == 0 && q.Failed == 0 && q.TimedOut == 0
+}
+
+// IsEmpty returns true if this metadata only contains zero-values.
+func (q *Quest_Desc_Meta) IsEmpty() bool {
+        return q.AsAccount == "" && q.Retry.IsEmpty()
+}
+
+var (
+        // QuestIDLength is the number of encoded bytes to use. It removes the
+        // single padding character.
+        QuestIDLength = base64.URLEncoding.EncodedLen(sha256.Size) - 1
+)
+
+// QuestDescPayloadMaxLength is the maximum length (in bytes) of an
+// un-normalized Quest payload.
+const QuestDescPayloadMaxLength = 256 * 1024
+
+// Normalize returns an error iff the Quest_Desc is invalid.
+func (q *Quest_Desc) Normalize() error {
+        if q.Meta == nil {
+                q.Meta = &Quest_Desc_Meta{Retry: &Quest_Desc_Meta_Retry{}}
+        } else if q.Meta.Retry == nil {
+                q.Meta.Retry = &Quest_Desc_Meta_Retry{}
+        }
+
+        if len(q.JsonPayload) > QuestDescPayloadMaxLength {
+                return fmt.Errorf("quest payload is too large: %d > %d",
+                        len(q.JsonPayload), QuestDescPayloadMaxLength)
+        }
+        normed, err := template.NormalizeJSON(q.JsonPayload, true)
+        if err != nil {
+                return fmt.Errorf("failed to normalize payload: %s", err)
+        }
+        q.JsonPayload = normed
+        return nil
+}
+
+// QuestID computes the DM compatible quest ID for this Quest_Desc. The
+// Quest_Desc should already be Normalize()'d.
+func (q *Quest_Desc) QuestID() string {
+        data, err := proto.Marshal(q)
+        if err != nil {
+                panic(err)
+        }
+        h := sha256.Sum256(data)
+        return base64.URLEncoding.EncodeToString(h[:])[:QuestIDLength]

[dnj (Google), 2016/06/09 18:00:57]

Note that if we ever change QuestIDLength, data could be hard to reach. TBH I'd
prefer we stick with full SHA256.

[iannucci, 2016/06/15 00:46:02]

? We do, we're just chopping off the extra, constant-length '=' padding at the
end.

+}