fix SASL handshake

Author: Achille Roussel

conn.go

@@ -1516,7 +1516,10 @@ func (c *Conn) saslAuthenticate(data []byte) ([]byte, error) {
 		return nil, err
 	}
 
+	// Pretend there are no limits to how many bytes we may be reading next.
+	c.rb.n = math.MaxInt64
 	data = c.rb.readBytes()
+	c.rb.n = 0
 
 	if err := c.rb.err; err != nil {
 		c.conn.Close()

sasl/sasl_test.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/segmentio/kafka-go"
+	kafka "github.com/segmentio/kafka-go"
 	"github.com/segmentio/kafka-go/sasl"
 	"github.com/segmentio/kafka-go/sasl/plain"
 	"github.com/segmentio/kafka-go/sasl/scram"
@@ -18,9 +18,6 @@ const (
 )
 
 func TestSASL(t *testing.T) {
-
-	t.Parallel()
-
 	tests := []struct {
 		valid    func() sasl.Mechanism
 		invalid  func() sasl.Mechanism