Fix for buggy clients

Author: simon-engledew

proxy/protocol/request_v1.go

@@ -42,6 +42,9 @@ func (r *Request) decode(pd packetDecoder) (err error) {
 	if version, err = pd.getInt16(); err != nil {
 		return err
 	}
+	if version == -1 {
+		version = r.Body.version()
+	}
 	if r.Body.key() != key || r.Body.version() != version {
 		return PacketDecodingError{fmt.Sprintf("expected request key,version %d,%d but got %d,%d", r.Body.key(), r.Body.version(), key, version)}
 	}

proxy/protocol/request_v2.go

@@ -42,6 +42,9 @@ func (r *RequestV2) decode(pd packetDecoder) (err error) {
 	if version, err = pd.getInt16(); err != nil {
 		return err
 	}
+	if version == -1 {
+		version = r.Body.version()
+	}
 	if r.Body.key() != key || r.Body.version() != version {
 		return PacketDecodingError{fmt.Sprintf("expected request key,version %d,%d but got %d,%d", r.Body.key(), r.Body.version(), key, version)}
 	}

proxy/protocol/responses.go

@@ -401,6 +401,7 @@ func modifyApiVersionsResponse(decodedStruct *Struct, fn config.NetAddressMappin
 
 	values := []any{int16(17), int16(0), int16(1)}
 
+	// version 3+ of the api versions response
 	if len(schema.GetFields()) > 3 {
 		values = append(values, []rawTaggedField{})
 	}

proxy/sasl_local.go

@@ -4,11 +4,12 @@ import (
 	"bytes"
 	"encoding/binary"
 	"fmt"
+	"io"
+	"time"
+
 	"github.com/grepplabs/kafka-proxy/pkg/apis"
 	"github.com/grepplabs/kafka-proxy/proxy/protocol"
 	"github.com/pkg/errors"
-	"io"
-	"time"
 )
 
 type LocalSasl struct {
@@ -146,6 +147,10 @@ func (p *LocalSasl) receiveAndSendAuthV1(conn DeadlineReaderWriter, localSaslAut
 		return errors.Errorf("SaslAuthenticate is expected, but got apiKey %d", requestKeyVersion.ApiKey)
 	}
 
+	if requestKeyVersion.ApiVersion == -1 {
+		requestKeyVersion.ApiVersion = 1
+	}
+
 	if requestKeyVersion.Length > protocol.MaxRequestSize {
 		return protocol.PacketDecodingError{Info: fmt.Sprintf("sasl authenticate message of length %d too large", requestKeyVersion.Length)}
 	}