From e6b823d64953284cfbc874de358700902129cdae Mon Sep 17 00:00:00 2001
From: Yuli Khodorkovskiy <yuli@crunchydata.com>
Date: Tue, 17 Dec 2019 20:03:55 -0500
Subject: [PATCH] Add missing GSSEncRequest

---
 backend.go         |  9 ++++++++-
 gss_enc_request.go | 49 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 gss_enc_request.go

diff --git a/backend.go b/backend.go
index 5741647f..cd7e8ce2 100644
--- a/backend.go
+++ b/backend.go
@@ -19,6 +19,7 @@ type Backend struct {
 	describe        Describe
 	execute         Execute
 	flush           Flush
+	gssEncRequest   GSSEncRequest
 	parse           Parse
 	passwordMessage PasswordMessage
 	query           Query
@@ -45,7 +46,7 @@ func (b *Backend) Send(msg BackendMessage) error {
 
 // ReceiveStartupMessage receives the initial connection message. This method is used of the normal Receive method
 // because the initial connection message is "special" and does not include the message type as the first byte. This
-// will return either a StartupMessage, SSLRequest, or CancelRequest.
+// will return either a StartupMessage, SSLRequest, GSSEncRequest, or CancelRequest.
 func (b *Backend) ReceiveStartupMessage() (FrontendMessage, error) {
 	buf, err := b.cr.Next(4)
 	if err != nil {
@@ -79,6 +80,12 @@ func (b *Backend) ReceiveStartupMessage() (FrontendMessage, error) {
 			return nil, err
 		}
 		return &b.cancelRequest, nil
+	case gssEncReqNumber:
+		err = b.gssEncRequest.Decode(buf)
+		if err != nil {
+			return nil, err
+		}
+		return &b.gssEncRequest, nil
 	default:
 		return nil, fmt.Errorf("unknown startup message code: %d", code)
 	}
diff --git a/gss_enc_request.go b/gss_enc_request.go
new file mode 100644
index 00000000..cf405a3e
--- /dev/null
+++ b/gss_enc_request.go
@@ -0,0 +1,49 @@
+package pgproto3
+
+import (
+	"encoding/binary"
+	"encoding/json"
+	"errors"
+
+	"github.com/jackc/pgio"
+)
+
+const gssEncReqNumber = 80877104
+
+type GSSEncRequest struct {
+}
+
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
+func (*GSSEncRequest) Frontend() {}
+
+func (dst *GSSEncRequest) Decode(src []byte) error {
+	if len(src) < 4 {
+		return errors.New("gss encoding request too short")
+	}
+
+	requestCode := binary.BigEndian.Uint32(src)
+
+	if requestCode != gssEncReqNumber {
+		return errors.New("bad gss encoding request code")
+	}
+
+	return nil
+}
+
+// Encode encodes src into dst. dst will include the 4 byte message length.
+func (src *GSSEncRequest) Encode(dst []byte) []byte {
+	dst = pgio.AppendInt32(dst, 8)
+	dst = pgio.AppendInt32(dst, gssEncReqNumber)
+	return dst
+}
+
+// MarshalJSON implements encoding/json.Marshaler.
+func (src GSSEncRequest) MarshalJSON() ([]byte, error) {
+	return json.Marshal(struct {
+		Type            string
+		ProtocolVersion uint32
+		Parameters      map[string]string
+	}{
+		Type: "GSSEncRequest",
+	})
+}