tests(sqlserver): fix test variable length packet fixture (#25658)

lib/srv/db/sqlserver/protocol/fixtures/packets.go

@@ -93,7 +93,8 @@ var (
 // partially Length-prefixed Bytes request, as described here: https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-tds/3f983fde-0509-485a-8c40-a9fa6679a828
 func RPCClientPartiallyLength(length uint64, chunks uint64) []byte {
 	packet := []byte{
-		0x03, 0x01, 0x00, 0x00, // Length placeholder
+		0x03, 0x01,
+		0x00, 0x00, // Length placeholder
 		0x00, 0x00, 0x01, 0x00, 0x16, 0x00, 0x00, 0x00,
 		0x12, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00,
 		0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00,
@@ -104,22 +105,32 @@ func RPCClientPartiallyLength(length uint64, chunks uint64) []byte {
 		0x00, 0x00, 0x00, 0x00, 0x00, // NVARCHARTYPE flags
 	}
 
+	// NVARCHARTYPE must have even length
+	if length%2 != 0 {
+		length += 1
+	}
+
 	packet = binary.LittleEndian.AppendUint64(packet, length)
 
 	if length > 0 && chunks > 1 {
 		chunkSize := length / chunks
 		rem := length
-		for rem > 0 {
+		for i := uint64(0); i < chunks-1; i++ {
 			packet = binary.LittleEndian.AppendUint32(packet, uint32(chunkSize))
 			data := make([]byte, chunkSize)
 			packet = append(packet, data...)
 			rem -= chunkSize
 		}
+
+		// Last chunk will contain the remaining data.
+		packet = binary.LittleEndian.AppendUint32(packet, uint32(rem))
+		data := make([]byte, rem)
+		packet = append(packet, data...)
 	}
 
 	// PLP_TERMINATOR
 	packet = append(packet, []byte{0x00, 0x00, 0x00, 0x00}...)
 
-	packet[3] = byte(len(packet))
+	binary.BigEndian.PutUint16(packet[2:], uint16(len(packet)))
 	return packet
 }