From 64188f07021950660bec3ed085cf8d941e158caa Mon Sep 17 00:00:00 2001
From: Dmitry Shulyak <yashulyak@gmail.com>
Date: Tue, 23 Apr 2019 10:04:58 +0300
Subject: [PATCH] Deliver envelopes in forward order (#1437)

---
 mailserver/db_key.go          | 10 ----------
 mailserver/mailserver.go      | 13 +++++--------
 mailserver/mailserver_test.go | 18 +++++++++---------
 3 files changed, 14 insertions(+), 27 deletions(-)

diff --git a/mailserver/db_key.go b/mailserver/db_key.go
index 5b3e58b07..9ea4bc8ab 100644
--- a/mailserver/db_key.go
+++ b/mailserver/db_key.go
@@ -53,13 +53,3 @@ func NewDBKeyFromBytes(b []byte) (*DBKey, error) {
 		hash:      common.BytesToHash(b[4:]),
 	}, nil
 }
-
-// mustNewDBKeyFromBytes panics if creating a key from a byte slice fails.
-// Check if a byte slice has DBKeyLength length before using it.
-func mustNewDBKeyFromBytes(b []byte) *DBKey {
-	k, err := NewDBKeyFromBytes(b)
-	if err != nil {
-		panic(err)
-	}
-	return k
-}
diff --git a/mailserver/mailserver.go b/mailserver/mailserver.go
index c95e091dd..2722fa6f6 100644
--- a/mailserver/mailserver.go
+++ b/mailserver/mailserver.go
@@ -479,17 +479,14 @@ func (s *WMailServer) createIterator(lower, upper uint32, cursor []byte) iterato
 		ku, kl    *DBKey
 	)
 
+	ku = NewDBKey(upper+1, emptyHash)
 	kl = NewDBKey(lower, emptyHash)
-	if len(cursor) == DBKeyLength {
-		ku = mustNewDBKeyFromBytes(cursor)
-	} else {
-		ku = NewDBKey(upper+1, emptyHash)
-	}
 
 	i := s.db.NewIterator(&util.Range{Start: kl.Bytes(), Limit: ku.Bytes()}, nil)
 	// seek to the end as we want to return envelopes in a descending order
-	i.Seek(ku.Bytes())
-
+	if len(cursor) == DBKeyLength {
+		i.Seek(cursor)
+	}
 	return i
 }
 
@@ -524,7 +521,7 @@ func (s *WMailServer) processRequestInBundles(
 	// append and continue.
 	// Otherwise publish what you have so far, reset the bundle to the
 	// current envelope, and leave if we hit the limit
-	for iter.Prev() {
+	for iter.Next() {
 		var envelope whisper.Envelope
 
 		decodeErr := rlp.DecodeBytes(iter.Value(), &envelope)
diff --git a/mailserver/mailserver_test.go b/mailserver/mailserver_test.go
index 8b6d814e7..901209de4 100644
--- a/mailserver/mailserver_test.go
+++ b/mailserver/mailserver_test.go
@@ -299,10 +299,10 @@ func (s *MailserverSuite) TestRequestPaginationLimit() {
 	defer s.server.Close()
 
 	var (
-		sentEnvelopes     []*whisper.Envelope
-		reverseSentHashes []common.Hash
-		receivedHashes    []common.Hash
-		archiveKeys       []string
+		sentEnvelopes  []*whisper.Envelope
+		sentHashes     []common.Hash
+		receivedHashes []common.Hash
+		archiveKeys    []string
 	)
 
 	now := time.Now()
@@ -316,7 +316,7 @@ func (s *MailserverSuite) TestRequestPaginationLimit() {
 		key := NewDBKey(env.Expiry-env.TTL, env.Hash())
 		archiveKeys = append(archiveKeys, fmt.Sprintf("%x", key.Bytes()))
 		sentEnvelopes = append(sentEnvelopes, env)
-		reverseSentHashes = append([]common.Hash{env.Hash()}, reverseSentHashes...)
+		sentHashes = append(sentHashes, env.Hash())
 	}
 
 	reqLimit := uint32(6)
@@ -334,11 +334,11 @@ func (s *MailserverSuite) TestRequestPaginationLimit() {
 	// 10 envelopes sent
 	s.Equal(count, uint32(len(sentEnvelopes)))
 	// 6 envelopes received
-	s.Equal(int(limit), len(receivedHashes))
-	// the 6 envelopes received should be in descending order
-	s.Equal(reverseSentHashes[:limit], receivedHashes)
+	s.Len(receivedHashes, int(limit))
+	// the 6 envelopes received should be in forward order
+	s.Equal(sentHashes[:limit], receivedHashes)
 	// cursor should be the key of the last envelope of the last page
-	s.Equal(archiveKeys[count-limit], fmt.Sprintf("%x", cursor))
+	s.Equal(archiveKeys[limit-1], fmt.Sprintf("%x", cursor))
 
 	// second page
 	receivedHashes, cursor, _ = processRequestAndCollectHashes(