proxy: remove sequence check

pkg/proxy/backend/authenticator.go

@@ -9,6 +9,7 @@ import (
 	"encoding/binary"
 	"fmt"
 	"net"
+	"strings"
 
 	"github.com/go-mysql-org/go-mysql/mysql"
 	"github.com/pingcap/tidb/util/hack"
@@ -212,11 +213,6 @@ loop:
 	for {
 		serverPkt, err := backendIO.ReadPacket()
 		if err != nil {
-			// tiproxy pp enabled, tidb pp disabled, tls disabled => invalid sequence
-			// tiproxy pp disabled, tidb pp enabled, tls disabled => invalid sequence
-			if pktIdx == 0 && errors.Is(err, pnet.ErrInvalidSequence) {
-				return errors.Wrap(ErrBackendPPV2, err)
-			}
 			return err
 		}
 		var packetErr *mysql.MyError
@@ -235,6 +231,18 @@ loop:
 			return err
 		}
 		if packetErr != nil {
+			// tiproxy pp enabled, tidb pp disabled, tls disabled => invalid sequence
+			// tiproxy pp disabled, tidb pp enabled, tls disabled => invalid sequence
+			for _, p := range []string{
+				"packets out of order",
+				"(nvali): d sequence",
+				"invalid sequence",
+				"PROXY Protocol",
+			} {
+				if strings.Contains(packetErr.Message, p) {
+					return errors.Wrap(ErrBackendPPV2, packetErr)
+				}
+			}
 			return errors.Wrap(ErrClientAuthFail, packetErr)
 		}
 

pkg/proxy/backend/authenticator_test.go

@@ -403,6 +403,10 @@ func TestProxyProtocol(t *testing.T) {
 	cfgOverriders := getCfgCombinations(cfgs)
 	for _, cfgs := range cfgOverriders {
 		ts, clean := newTestSuite(t, tc, cfgs...)
+		// invalid sequence detection removed, backend will stuck if clients insists to send proxy header.
+		if !ts.mb.proxyProtocol && ts.mp.bcConfig.ProxyProtocol {
+			continue
+		}
 		ts.authenticateFirstTime(t, func(t *testing.T, ts *testSuite) {
 			// TiDB proxy-protocol can be set unfallbackable, but TiProxy proxy-protocol is always fallbackable.
 			// So when backend enables proxy-protocol and proxy disables it, it still works well.

pkg/proxy/backend/error.go

@@ -79,7 +79,7 @@ const (
 	SrcClientSQLErr
 	// SrcProxyQuit includes: proxy graceful shutdown
 	SrcProxyQuit
-	// SrcProxyMalformed includes: malformed packet; invalid sequence
+	// SrcProxyMalformed includes: malformed packet
 	SrcProxyMalformed
 	// SrcProxyNoBackend includes: no backends
 	SrcProxyNoBackend

pkg/proxy/net/packetio.go

@@ -246,11 +246,7 @@ func (p *PacketIO) readOnePacket() ([]byte, bool, error) {
 	if err := ReadFull(p.readWriter, p.header); err != nil {
 		return nil, false, errors.Wrap(ErrReadConn, err)
 	}
-	sequence, pktSequence := p.header[3], p.readWriter.Sequence()
-	if sequence != pktSequence {
-		return nil, false, ErrInvalidSequence.GenWithStack("invalid sequence, expected %d, actual %d", pktSequence, sequence)
-	}
-	p.readWriter.SetSequence(sequence + 1)
+	p.readWriter.SetSequence(p.header[3] + 1)
 
 	length := int(p.header[0]) | int(p.header[1])<<8 | int(p.header[2])<<16
 	data := make([]byte, length)
@@ -350,11 +346,7 @@ func (p *PacketIO) ForwardUntil(dest *PacketIO, isEnd func(firstByte byte, first
 			}
 		} else {
 			for {
-				sequence, pktSequence := header[3], p.readWriter.Sequence()
-				if sequence != pktSequence {
-					return p.wrapErr(ErrInvalidSequence.GenWithStack("invalid sequence, expected %d, actual %d", pktSequence, sequence))
-				}
-				p.readWriter.SetSequence(sequence + 1)
+				p.readWriter.SetSequence(header[3] + 1)
 				// Sequence may be different (e.g. with compression) so we can't just copy the data to the destination.
 				dest.readWriter.SetSequence(dest.readWriter.Sequence() + 1)
 				p.limitReader.N = int64(length + 4)