fix bug of read to many bytes

session-dealer/mysql/session.go

@@ -12,17 +12,17 @@ import (
 )
 
 type MysqlSession struct {
-	connectionID             *string
-	visitUser                *string
-	visitDB                  *string
-	clientHost               *string
-	clientPort               int
-	serverIP                 *string
-	serverPort               int
-	stmtBeginTime            int64
+	connectionID  *string
+	visitUser     *string
+	visitDB       *string
+	clientHost    *string
+	clientPort    int
+	serverIP      *string
+	serverPort    int
+	stmtBeginTime int64
 	// packageOffset            int64
-	beginSeqID        int64
-	endSeqID        int64
+	beginSeqID               int64
+	endSeqID                 int64
 	coverRanges              *coverRanges
 	expectReceiveSize        int
 	expectSendSize           int
@@ -59,7 +59,7 @@ func NewMysqlSession(
 		queryPieceReceiver: receiver,
 		closeConn:          make(chan bool, 1),
 		expectReceiveSize:  -1,
-		coverRanges: NewCoverRanges(),
+		coverRanges:        NewCoverRanges(),
 		ignoreAckID:        -1,
 		sendSize:           0,
 		pkgCacheLock:       sync.Mutex{},
@@ -100,7 +100,7 @@ func (ms *MysqlSession) resetBeginTime() {
 }
 
 func (ms *MysqlSession) readFromServer(bytes []byte) {
-	if ms.expectSendSize < 1 {
+	if ms.expectSendSize < 1 && len(bytes) > 4 {
 		ms.expectSendSize = extractMysqlPayloadSize(bytes[:4])
 		contents := bytes[4:]
 		if ms.prepareInfo != nil && contents[0] == 0 {
@@ -115,7 +115,7 @@ func (ms *MysqlSession) checkFinish() bool {
 	}
 
 	checkNode := ms.coverRanges.head.next
-	if checkNode.end - checkNode.begin == int64(len(ms.cachedStmtBytes)) {
+	if checkNode.end-checkNode.begin == int64(len(ms.cachedStmtBytes)) {
 		return true
 	}
 
@@ -160,7 +160,6 @@ func (ms *MysqlSession) readFromClient(seqID int64, bytes []byte) {
 		ms.beginSeqID = seqID
 		ms.endSeqID = seqID
 
-
 		if int64(ms.expectReceiveSize) < int64(len(contents)) {
 			log.Warnf("receive invalid mysql packet")
 			return
@@ -192,7 +191,7 @@ func (ms *MysqlSession) readFromClient(seqID int64, bytes []byte) {
 		if seqOffset+contentSize > int64(len(ms.cachedStmtBytes)) {
 			// not in a normal mysql packet
 			log.Debugf("receive an unexpect packet")
-			 ms.clear()
+			ms.clear()
 			return
 		}
 
@@ -204,7 +203,6 @@ func (ms *MysqlSession) readFromClient(seqID int64, bytes []byte) {
 	// ms.expectReceiveSize = ms.expectReceiveSize - int(contentSize)
 }
 
-
 func (ms *MysqlSession) GenerateQueryPiece() (qp model.QueryPiece) {
 	defer ms.clear()